Chemical Formula: Fe Locality: Asteroid fragments and in German and Greenland basalts. Name Origin: Probably Anglo-Saxon in origin.
Iron is a chemical element with symbol Fe (from Latin: ferrum) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth’s outer and inner core. It is the fourth most common element in the Earth’s crust. Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars, where the production of nickel-56 (which decays to the most common isotope of iron) is the last nuclear fusion reaction that is exothermic. Consequently, radioactive nickel is the last element to be produced before the violent collapse of a supernova scatters precursor radionuclide of iron into space.
Occurrence
Planetary occurrence
Iron is the sixth most abundant element in the Universe, and the most common refractory element. It is formed as the final exothermic stage of stellar nucleosynthesis, by silicon fusion in massive stars.
Metallic or native iron is rarely found on the surface of the Earth because it tends to oxidize, but its oxides are pervasive and represent the primary ores. While it makes up about 5% of the Earth’s crust, both the Earth’s inner and outer core are believed to consist largely of an iron-nickel alloy constituting 35% of the mass of the Earth as a whole. Iron is consequently the most abundant element on Earth, but only the fourth most abundant element in the Earth’s crust. Most of the iron in the crust is found combined with oxygen as iron oxide minerals such as hematite (Fe2O3) and magnetite (Fe3O4). Large deposits of iron are found in banded iron formations. These geological formations are a type of rock consisting of repeated thin layers of iron oxides alternating with bands of iron-poor shale and chert. The banded iron formations were laid down in the time between 3,700 million years ago and 1,800 million years ago
About 1 in 20 meteorites consist of the unique iron-nickel minerals taenite (35–80% iron) and kamacite (90–95% iron). Although rare, iron meteorites are the main form of natural metallic iron on the Earth’s surface.
The red color of the surface of Mars is derived from an iron oxide-rich regolith. This has been proven by Mössbauer spectroscopy.
The Amur River or Heilong Jiang is the world’s tenth longest river, forming the border between the Russian Far East and Northeastern China (Inner Manchuria). The largest fish species in the Amur is the kaluga, attaining a length as great as 5.6 metres.
Name
The Chinese name for this river, Heilong Jiang, means Black Dragon River in English, and its Mongolian name, Khar mörön (Cyrillic: Хар мөрөн), means Black River.
Course
This river rises in the hills of western Manchuria at the confluence of its two major affluents, the Shilka River and the Ergune (or Argun) River, at an elevation of 303 metres (994 ft). It flows east forming the border between China and Russia, and slowly makes a great arc to the southeast for about 400 kilometres (250 mi), receiving many tributaries and passing many small towns. At Huma, it is joined by a major tributary, the Huma River. Afterwards it continues to flow south until between the cities of Blagoveschensk (Russia) and Heihe (China), it widens significantly as it is joined by the Zeya River, one of its most important tributaries.
The Amur arcs to the east and turns southeast again at the confluence with the Bureya River, then does not receive another significant tributary for nearly 250 kilometres (160 mi) before its confluence with its largest tributary, the Songhua River, at Tongjiang. At the confluence with the Songhua the river turns northeast, now flowing towards Khabarovsk, where it joins the Ussuri River and ceases to define the Russia-China border. Now the river spreads out dramatically into a braided character, flowing north-northeast through a wide valley in eastern Russia, passing Amursk and Komsomolsk-on-Amur. The valley narrows after about 200 kilometres (120 mi) and the river again flows north onto plains at the confluence with the Amgun River. Shortly after the Amur turns sharply east and into an estuary at Nikolayevsk-on-Amur, about 20 kilometres (12 mi) downstream of which it flows into the Strait of Tartary
History and context
In many historical references these two geopolitical entities are known as Outer Manchuria (Russian Manchuria) and Inner Manchuria, respectively. The Chinese province of Heilongjiang on the south bank of the river is named after it, as is the Russian Amur Oblast on the north bank. The name Black River (sahaliyan ula) was used by the Manchu and the Ta-tsing Empire who regarded this river as sacred.
The Amur River is a very important symbol of — and an important geopolitical factor in — Chinese-Russian relations. The Amur was especially important in the period of time following the Sino-Soviet political split in the 1960s.
For many centuries the Amur Valley was populated by the Tungusic (Evenki, Solon, Ducher, Jurchen, Nanai, Ulch) and Mongol (Daur) people, and, near its mouth, by the Nivkhs. For many of them, fishing in the Amur and its tributaries was the main source of their livelihood. Until the 17th century, these people were not known to the Europeans, and little known to the Han people, who sometimes collectively described them as the Wild Jurchens. The term Yupi Dazi (“Fish-skin Tatars”) was used for the Nanais and related groups as well, owing to their traditional clothes made of fish skins.
The Mongols, ruling the region as the Yuan Dynasty, established a tenuous military presence on the lower Amur in the 13-14th centuries; ruins of a Yuan-era temple have been excavated near the village of Tyr .
During the Yongle and Xuande era (early 15th century) the Ming Dynasty reached the Amur as well in their drive to establish control over the lands adjacent to the Ming Empire from the northeast, which were to become later known as Manchuria. Expeditions headed by the eunuch Yishiha reached Tyr several times between 1411 and the early 1430s, re-building (twice) the Yongning Temple and obtaining at least nominal allegiance of the lower Amur’s tribes to the Ming government.Some sources report also the Chinese presence during the same period on the middle Amur, with a fort – a predecessor of later Aigun – existing for about 20 years during the Yongle era on the left (northwestern) shore of the Amur, downstream from the mouth of the Zeya (opposite to the location of the later, Qing, Aigun). In any event, the Ming presence on the Amur was as short-lived as it was tenuous; soon after the end of the Yongle reign, the dynasty’s frontiers retreated to southern Manchuria.
The 17th century saw the conflict over the control of the Amur between the Russians, expanding into eastern Siberia, and the recently risen Qing Empire, whose original base was in south-eastern Manchuria. Russian Cossack expeditions led by Vassili Poyarkov and Yerofey Khabarov explored the Amur and its tributaries in 1643-1644 and 1649–1651, respectively. The Cossacks established the fort of Albazin on the upper Amur, at the site of the former capital of the Solons.
Amur River (under its Manchu name, Saghalien Oula) and its tributaries on a 1734 map by Jean Baptiste Bourguignon d’Anville, based upon maps of Jesuits in China. Albazin is shown as Jaxa, the old (Ming) site of Aigun as Aihom and the later, Qing Aigun, as Saghalien Oula.
At the time, the Manchus were busy with conquering the region; but a few decades later, during the Kangxi reign they turned their attention to their north-Manchurian backyard. Aigun was reestablished near the supposed Ming site ca. 1683-1684, and a military expeditions was sent upstream, to dislodge the Russians, whose Albazin establishment deprived the Manchu rulers from the tribute of sable pelts that the Solons and Daurs of the area would supply otherwise. Albazin fell during a short military campaign in 1685. The hostilities were concluded in 1689 by the Treaty of Nerchinsk, which left the entire Amur valley, from the convergence of the Shilka and the Ergune downstream, in the Chinese hands.
The Amur region remained a relative backwater of the Ta-tsing Empire for the next century and a half, with Aigun being practically the only major town on the river. Russians re-appeared on the river in the mid-19th century, forcing the Manchus to yield all lands north of the river to the Russian Empire by the Treaty of Aigun (1858). Lands east of the Ussury and the lower Amur were acquired by Russia as well, by the Convention of Peking (1860).
The acquisition of the lands on the Amur and the Ussury was followed by the migration of Russian settlers to the region and the construction of such cities as Blagoveshchensk and, later, Khabarovsk.
Numerous river steamers plied the Amur by the late 19th century. Mining dredges were imported from America to work the placer gold of the river. Barge and river traffic was greatly hindered by the Civil War of 1918-22. The ex-German Yangtse gunboats Vaterland and Otter, on Chinese Nationalist Navy service, patrolled the Amur in the 1920s.
Note : The above story is based on materials provided by Wikipedia
Methane bubbles rising from the seafloor. Credit: NOAA-OER/BOEM/USGS
In 2011, Jennifer Glass joined a scientific cruise to study a methane seep off of Oregon’s coast. In these cold, dark depths, microbes buried in the sediment feast on methane that seeps through the seafloor.
A product of their metabolism, bicarbonate, reacts with calcium in seawater to form tall rocky deposits. The chemical energy these organisms extract from methane supports a vibrant underworld—an eclectic blanket of microbial mats, clam fields and tube worms.
“It’s such a beautiful landscape,” says Glass, an alumnus of NASA’s Astrobiology post-doctoral program and now assistant professor at the Georgia Institute of Technology. “You have these huge mountains on the sea floor, housing these incredible ecosystems.”
In March, Glass presented some of her work on methane and microbes in the second lecture for NASA’s Astrobiology Postdoctoral Program seminar series. In her talk, “Microbes, Methane, and Metals,” Glass discussed the importance of metals as nutrients for these microbes.
Glass’s work has a broader implication for understanding greenhouse gas cycles and climate change. Methane is a greenhouse gas that is approximately 25 times more potent than carbon dioxide. Recently, atmospheric methane has been increasing after a decade-long hiatus. While scientists aren’t entirely sure why, they suspect a combination of methane-producing microbes in wetlands and the warming of high latitude permafrost. What’s more, recent findings suggest that methane-spewing microbes may have contributed to our Earth’s biggest extinction, the “Great Dying,” 250 million years ago.
The methane-eating microbes that Glass studies play an important role in the methane cycle, keeping in check additional release of methane from cold seeps, where it is stored as an ice-like structure that slowly trickles through the sea floor.
Glass first learned about these ecosystems while studying oceanography in college, and quickly became fascinated by them. “I could gush poetically,” she says, offering the link to a long piece she wrote for the magazine Northwest Science and Technology in 2006 (Methane Mimosas on Ice).
But she did not get to work on them until years later, when she became an Astrobiology NPP postdoc in the lab of Victoria Orphan, a geobiologist at the California Institute of Technology. On her first day, Glass and her new colleagues boarded the RV Atlantis on a scientific expedition off of Oregon’s coast. Using the Remotely Operated Vehicle Jason, they collected microbes and sediments from the sea floor.
From these samples emerged a surprising discovery.
The group found evidence of a new microbial enzyme that seems to use the trace metal tungsten instead of molybdenum, the metal more commonly found in cold seep environments. Previously, tungsten had only been found in microbes living at high temperatures, such as the boiling waters of hydrothermal vents. The group’s findings were published last year in the journal Environmental Microbiology.
“It’s a very unique chemical environment, with a lot of sulfur,” Glass says. “We think that tungsten might just be more bio-available in these highly sulfidic conditions.”
“Overall, we’re hoping to get a better understanding of alternative pathways of greenhouse gas cycling,” she says. “Our main goal here was to understand how the environment in these deep sea methane seeps influences microbe metabolism, and specifically the trace-metal chemistry. And no one had really looked into these specific chemicals before.”
In collaboration with colleagues at Georgia Tech as well as Sean Crowe of the University of British Columbia and David Fowle of the University of Kansas, Glass has now begun new studies in Lake Matano, Indonesia as an analogue for oceans on early Earth. The deep waters of Lake Matano are poor in oxygen and rich in iron and methane, factors likely characteristic of ancient oceans.
“We’re looking to pull out unique microbes from these sediments,” she says. “And so far, the evidence suggests that microbes may be coupling methane and iron redox cycles to survive at the bottom of Lake Matano.”
While excessive methane release in the atmosphere could be catastrophic for life today, it may not always have been the case. On early Earth, our Sun was 30 percent fainter than it is today. Scientists believe that atmospheric methane may have kept the Earth warm enough to prevent water from freezing, enabling the emergence and evolution of early life.
What’s more, these systems don’t depend on oxygen, Glass explains. So the microbe-methane relationship likely developed early in Earth’s history before the rise of oxygen.
They could also serve as analogues for worlds beyond our Earth. Methane has been detected in the atmosphere of other planets. Methane lakes have also been spotted on Titan, Saturn’s largest moon, making it an intriguing candidate for life elsewhere.
Note : The above story is based on materials provided by Astrobio
Chemical Formula: Ca(H4B3O7)(OH)·4H2O Locality: Mount Blanco mine, Mount Blanco, Black Mountains, Death Valley, Inyo County, California. Name Origin: Named after it’s locality.
Inyoite, named after Inyo County, California, where it was discovered in 1914, is a colourless monoclinic mineral. It turns white on dehydration. Its chemical formula is Ca(H4B3O7)(OH)·4H2O or CaB3O3(OH)5·4(H2O).
Physical Properties
Cleavage: {001} Good Color: White, Pinkish white. Density: 1.87 Diaphaneity: Transparent to Translucent Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern. Hardness: 2 – Gypsum Luminescence: Non-fluorescent. Luster: Vitreous (Glassy) Magnetism: Nonmagnetic Streak: white
More than a mile beneath the ocean’s surface, microbial pirates board treasure-laden ships. Credit: NOAA
More than a mile beneath the ocean’s surface, as dark clouds of mineral-rich water billow from seafloor hot springs called hydrothermal vents, unseen armies of viruses and bacteria wage war.
Like pirates boarding a treasure-laden ship, the viruses infect bacterial cells to get the loot: tiny globules of elemental sulfur stored inside the bacterial cells.
Instead of absconding with their prize, the viruses force the bacteria to burn their valuable sulfur reserves, then use the unleashed energy to replicate.
“Our findings suggest that viruses in the dark oceans indirectly access vast energy sources in the form of elemental sulfur,” said University of Michigan marine microbiologist and oceanographer Gregory Dick, whose team collected DNA from deep-sea microbes in seawater samples from hydrothermal vents in the Western Pacific Ocean and the Gulf of California.
“We suspect that these viruses are essentially hijacking bacterial cells and getting them to consume elemental sulfur so the viruses can propagate themselves,” said Karthik Anantharaman of the University of Michigan, first author of a paper on the findings published this week in the journal Science Express.
Similar microbial interactions have been observed in shallow ocean waters between photosynthetic bacteria and the viruses that prey upon them.
But this is the first time such a relationship has been seen in a chemosynthetic system, one in which the microbes rely solely on inorganic compounds, rather than sunlight, as their energy source.
“Viruses play a cardinal role in biogeochemical processes in ocean shallows,” said David Garrison, a program director in the National Science Foundation’s (NSF) Division of Ocean Sciences, which funded the research. “They may have similar importance in deep-sea thermal vent environments.”
The results suggest that viruses are an important component of the thriving ecosystems–which include exotic six-foot tube worms–huddled around the vents.
“The results hint that the viruses act as agents of evolution in these chemosynthetic systems by exchanging genes with the bacteria,” Dick said. “They may serve as a reservoir of genetic diversity that helps shape bacterial evolution.”
The scientists collected water samples from the Eastern Lau Spreading Center in the Western Pacific Ocean and the Guaymas Basin in the Gulf of California.
The samples were taken at depths of more than 6,000 feet, near hydrothermal vents spewing mineral-rich seawater at temperatures surpassing 500 degrees Fahrenheit.
Back in the laboratory, the researchers reconstructed near-complete viral and bacterial genomes from DNA snippets retrieved at six hydrothermal vent plumes.
In addition to the common sulfur-consuming bacterium SUP05, they found genes from five previously unknown viruses.
The genetic data suggest that the viruses prey on SUP05. That’s not too surprising, said Dick, since viruses are the most abundant biological entities in the oceans and are a pervasive cause of mortality among marine microorganisms.
The real surprise, he said, is that the viral DNA contains genes closely related to SUP05 genes used to extract energy from sulfur compounds.
When combined with results from previous studies, the finding suggests that the viruses force SUP05 bacteria to use viral SUP05-like genes to help process stored globules of elemental sulfur.
The SUP05-like viral genes are called auxiliary metabolic genes.
“We hypothesize that the viruses enhance bacterial consumption of this elemental sulfur, to the benefit of the viruses,” said paper co-author Melissa Duhaime of the University of Michigan. The revved-up metabolic reactions may release energy that the viruses then use to replicate and spread.
How did SUP05-like genes end up in these viruses? The researchers can’t say for sure, but the viruses may have snatched genes from SUP05 during an ancient microbial interaction.
“There seems to have been an exchange of genes, which implicates the viruses as an agent of evolution,” Dick said.
All known life forms need a carbon source and an energy source. The energy drives the chemical reactions used to assemble cellular components from simple carbon-based compounds.
On Earth’s surface, sunlight provides the energy that enables plants to remove carbon dioxide from the air and use it to build sugars and other organic molecules through the process of photosynthesis.
But there’s no sunlight in the deep ocean, so microbes there often rely on alternate energy sources.
Instead of photosynthesis they depend on chemosynthesis. They synthesize organic compounds using energy derived from inorganic chemical reactions–in this case, reactions involving sulfur compounds.
Sulfur was likely one of the first energy sources that microbes learned to exploit on the young Earth, and it remains a driver of ecosystems found at deep-sea hydrothermal vents, in oxygen-starved “dead zones” and at Yellowstone-like hot springs.
Dick said the new microbial findings will help researchers understand how marine biogeochemical cycles, including the sulfur cycle, will respond to global environmental changes such as the ongoing expansion of dead zones.
SUP05 bacteria, which are known to generate the greenhouse gas nitrous oxide, will likely expand their range as oxygen-starved zones continue to grow in the oceans.
In addition to Anantharaman, Dick and Duhaime, co-authors of the Science Express paper are John Breir of the Woods Hole Oceanographic Institution, Kathleen Wendt of the University of Minnesota and Brandy Toner of the University of Minnesota.
The project was also funded by the Gordon and Betty Moore Foundation and the University of Michigan Rackham Graduate School Faculty Research Fellowship Program.
Note : The above story is based on materials provided by National Science Foundation.
Deep underground, microbes have to breathe iron and sulfur to get energy. Argonne scientists announced they have found what appears to be a missing step in the iron-sulfur cycle in underground aquifers. It turns out that sulfur (white-yellow power, on top) may be far more essential than previously thought in helping microbes harvest energy from iron minerals (from top to bottom: yellow goethite, red hematite, orange lepidocrocite) and produce sulfur-iron minerals, like mackinawhite (black). Understanding these cycles is important for carbon sequestration and for predicting the fate of ground pollution. Credit: Mark Lopez/Argonne National Laboratory.
A study published today in Science by researchers from the U.S. Department of Energy’s Argonne National Laboratory may dramatically shift our understanding of the complex dance of microbes and minerals that takes place in aquifers deep underground. This dance affects groundwater quality, the fate of contaminants in the ground and the emerging science of carbon sequestration.
Deep underground, microbes don’t have much access to oxygen. So they have evolved ways to breathe other elements, including solid minerals like iron and sulfur.
The part that interests scientists is that when the microbes breathe solid iron and sulfur, they transform them into highly reactive dissolved ions that are then much more likely to interact with other minerals and dissolved materials in the aquifer. This process can slowly but steadily make dramatic changes to the makeup of the rock, soil and water.
“That means that how these microbes breathe affects what happens to pollutants—whether they travel or stay put—as well as groundwater quality,” said Ted Flynn, a scientist from Argonne and the Computation Institute at the University of Chicago and the lead author of the study.
About a fifth of the world’s population relies on groundwater from aquifers for their drinking water supply, and many more depend on the crops watered by aquifers.
For decades, scientists thought that when iron was present in these types of deep aquifers, microbes who can breathe it would out-compete those who cannot. There’s an accepted hierarchy of what microbes prefer to breathe, according to how much energy each reaction can theoretically yield. (Oxygen is considered the best overall, but it is rarely found deep below the surface.)
According to these calculations, of the elements that do show up in these aquifers, breathing iron theoretically provides the most energy to microbes. And iron is frequently among the most abundant minerals in many aquifers, while solid sulfur is almost always absent.
This illustration shows the new sulfur and iron cycle proposed by Argonne researchers in a new paper out today in Science magazine. In very alkaline environments, microbes that reduce sulfur and iron co-exist. Credit: Ted Flynn/Science.
But something didn’t add up right. A lot of the microorganisms had equipment to breathe both iron and sulfur. This requires two completely different enzymatic mechanisms, and it’s evolutionarily expensive for microbes to keep the genes necessary to carry out both processes. Why would they bother, if sulfur was so rarely involved?
The team decided to redo the energy calculations assuming an alkaline environment—”Older and deeper aquifers tend to be more alkaline than pH-neutral surface waters,” said Argonne coauthor Ken Kemner—and found that in alkaline environments, it gets harder and harder to get energy out of iron.
“Breathing sulfur, on the other hand, becomes even more favorable in alkaline conditions,” Flynn said.
The team reinforced this hypothesis in the lab with bacteria under simulated aquifer conditions. The bacteria, Shewanella oneidensis, can normally breathe both iron and sulfur. When the pH got as high as 9, however, it could breathe sulfur, but not iron.
There was still the question of where microorganisms like Shewanella could find sulfur in their native habitat, where it appeared to be scarce.
The answer came from another group of microorganisms that breathe a different, soluble form of sulfur called sulfate, which is commonly found in groundwater alongside iron minerals. These microbes exhale sulfide, which reacts with iron minerals to form solid sulfur and reactive iron. The team believes this sulfur is used up almost immediately by Shewanella and its relatives.
“This explains why we don’t see much sulfur at any fixed point in time, but the amount of energy cycling through it could be huge,” Kemner said.
Indeed, when the team put iron-breathing bacteria in a highly alkaline lab environment without any sulfur, the bacteria did not produce any reduced iron.
“This hypothesis runs counter to the prevailing theory, in which microorganisms compete, survival-of-the-fittest style, and one type of organism comes out dominant,” Flynn said. Rather, the iron-breathing and the sulfate-breathing microbes depend on each other to survive.
Understanding this complex interplay is particularly important for sequestering carbon. The idea is that in order to keep harmful carbon dioxide out of the atmosphere, we would compress and inject it into deep underground aquifers. In theory, the carbon would react with iron and other compounds, locking it into solid minerals that wouldn’t seep to the surface.
Iron is one of the major players in this scenario, and it must be in its reactive state for carbon to interact with it to form a solid mineral. Microorganisms are essential in making all that reactive iron. Therefore, understanding that sulfur—and the microbe junkies who depend on it—plays a role in this process is a significant chunk of the puzzle that has been missing until now.
Note : The above story is based on materials provided by Argonne National Laboratory
Chemical Formula: Ca2(Mn,Fe)7Si10O28(OH)2·5H2O Locality: Banska Stiavnica, Czechoslovakia. Name Origin: From the Greek ines – “flesh fibers.”
Inesite is not a common mineral in rock shops and in mineral displays. However it can form attractive pink or rose colored specimens that are sought after by mineral collectors. The commonly seen prismatic crystals have a slanted or “chisel-shaped” termination. At first glance the shorter crystals may be mistaken for rhombohedrons which have six equally slanted faces. Inesite will show only one steeply slanted face, while the other faces have a much less inclined slant. This is important for identification because the pink to rose colored mineral rhodochrosite forms rhombohedrons. Another similar looking mineral is the silicate rhodonite. Fortunately rhodonite lacks any steeply inclined faces and is normally blocky, not prismatic.
A pore-scale model or micromodel is designed to mimic the pore structure of the material being investigated by imprinting tiny replicas of it onto silicon wafers.
The impacts of biogeochemical processes in the underworld beneath our feet are on massive scales. Thousands of microbial species dine on organic molecules, belching their leftovers back into the soil and upwards into the atmosphere. Mineral-laden aquifers pulse with water that seasonally comingles with rivers rushing overhead. Fissures and faults in the earth provide conduits for subsurface chemicals to rise into the air. Each of these processes varies depending on the climate, the composition of minerals, and the tectonics of each region on the planet. Understanding what’s going on down there, and how it effects what’s going on up here, sounds like a herculean order. But at EMSL, scientists are getting a handle on these enormous macroscopic processes by zooming down to the microscopic scale.
By imprinting tiny replicas of sediment onto silicon wafers and employing a battery of imaging techniques to watch what unfolds as fluids pass through, scientists are observing the molecular processes that underpin massive ones, such as the carbon cycle and the transport of subsurface contaminants. EMSL scientists and users are interested in understanding all of these large processes and more, by examining them at the size that matters most: the pore scale.
Through creation of micron-scale models akin to tiny high-tech ant farms, and incorporation of supercomputer simulations that take diverse biogeochemical factors into account, researchers hope to connect what they learn at the molecular level with processes that affect our entire ecosystem.
“We’re starting with these molecular, pore-scale processes and tying them into the big earth-water system, and that’s crossing many, many scales,” says Nancy Hess, a Science Theme lead at EMSL.
Radioactive pores
The spread of subsurface contaminants depends largely upon whether they dissolve in mobile groundwater, or form precipitates that stay put. In the case of a uranium plume that lurks underground at the Hanford Site less than two miles from EMSL, scientists need to understand how fast contaminants will encroach on the nearby Columbia River. Even more pressing scenarios are playing out in contaminated uranium mining sites near waterways. The oxidation state of uranium is the main factor that dictates whether the contaminant becomes soluble (and therefore mobile), and the way uranium interacts with minerals dictates its oxidation state. Oxidized uranium (VI) is highly soluble, whereas its reduced cousin, uranium (IV), tends to precipitate.
Just measuring the chemical species present underground gives researchers a crude view of the complex interactions that dictate uranium precipitation, says Hess. In reality, steep geochemical gradients, consisting of mobile phases that flow through rock or percolate into it, create a dynamic mix of chemical species. The best way to truly understand these steep gradients and how they affect contaminants is to go down to the micron scale.
“We can create very steep geochemical gradients within these pore-scale models,” Hess says. “We’ve found that uranium may be in a very oxidizing environment during advective flow, but it can diffuse into a region that’s actually quite reducing. These reducing microenvironments lead to the trapping or sequestration of contaminants at a higher level than you would expect if you took this macroscopic view of the environment.”
Researchers can also use micromodels to predict how contaminants might respond to remediation efforts. For example, uranium can precipitate when it reacts with phosphate, so researchers have attempted to curb uranium mobility by amending the subsurface with phosphate. The process had been studied on larger scales – in bottles, core samples and in the field.
“What was missing was a fundamental understanding how groundwater flow, solute mixing and groundwater chemistry affect precipitation, and the form of the uranium phosphate that develops,” said Charles Werth of the University of Illinois at Urbana-Champaign. “We want to understand how groundwater conditions affect what’s forming, so we can then determine the potential for uranium remobilization in the future.”
Werth collaborated with EMSL researchers to build a micromodel and to study uranium transport and precipitation in response to phosphate addition. Much like fabrication of a microchip, the researchers used plasma etching to create a representative pore structure on a silicon wafer. Sealed with a glass coverslip and equipped with inlets and outlets, the micromodel allowed researchers to pump uranium, phosphate and other common groundwater constituents through the pore structure and view precipitation reactions in real time. The team used brightfield reflected microscopy to watch precipitates form, and employed Raman backscattering spectroscopy and micro X-ray diffraction to distinguish the mineralogy and chemical makeup of the precipitates.
Chernikovite, a uranium phosphate mineral, in a single micromodel pore imaged with brightfield reflected microscopy. The rounded edges of the two-dimensional grains are visible on the left and right sides of the image. Credit: Charles Werth, University of Illinois at Urbana-Champaign
The researchers found uranium and phosphate precipitate into a mineral called chernikovite and this mineral rapidly clogs pores and reduces flow. The precipitation is a desirable effect; however, the dramatic pore blockage could limit the spread of phosphate underground, the team concluded.
“The advantage the micromodels give is they allow direct observation and spectroscopic interrogation of reactions occurring in a groundwater system,” Werth said. “The results give us insights into how effective that process might be at trapping uranium in the subsurface.”
The microbe factor
EMSL users also have their sights set on understanding how microscopic soil processes affect the carbon cycle. Plants remove carbon dioxide from the atmosphere, and later that carbon incorporates into the soil when the plants die. Microbes in the soil then digest the carbon and release it back into the atmosphere. Understanding the processes that affect microbial breakdown of carbon will have major impacts on models of climate change. As of now, the contribution of microbes to atmospheric carbon is a black box, says mineralogist Markus Kleber of Oregon State University in Corvallis. Kleber’s team plans to use EMSL’s expertise and instruments to understand how different minerals in the soil affect the ability of microbes to break down organic material.
Unlike humans and other animals, Kleber says, “microbes are tiny, and they have no mouth.” This seemingly obvious distinction makes a big difference in the way microbes digest carbon. Rather than processing their food internally, microbes must secrete enzymes into the surrounding soil to break down large organic molecules, such as cellulose. The microbes can then transport the smaller breakdown products across their membranes and utilize them for energy. This external digestion process means the secreted enzymes must carry out their functions amidst minerals in the soil.
Some mineral surfaces, such as manganese oxide and iron oxide, are considered “catalytic,” and may have catastrophic effects on the structure and, therefore, the function of microbial enzymes. “How do microbial enzymes interact with mineral surfaces?” Kleber wants to know. “Do they simply absorb, get a little dented, but otherwise stick around? Or do the enzymes come in contact with a very reactive mineral surface and get blown apart?”
To find out, Kleber and graduate student Stephany Chacon will collaborate with EMSL scientists to measure the structural changes that occur in proteins when they interact with various minerals. Using 2-dimensional nuclear magnetic resonance spectroscopy and Fourier transform ion cyclotron resonance, or FT-ICR, mass spectrometry, Kleber and Chacon will assess the structural changes that occur in a model protein when it interacts with manganese oxide and other reactive surfaces. The team will then mutate the protein to understand how various amino acid changes affect the way the protein survives mineral encounters. Kleber hopes the findings will eventually allow researchers to incorporate the known distribution of soil minerals on the planet into the Department of Energy-sponsored Community Land Model.
Permafrost secrets
No soil on the planet harbors as much subsurface carbon as does Arctic permafrost. Frozen underground for millennia, the carbon residing there is gradually breaking out of its icy cage as the planet warms, and soil microbes are awakening from their chilly slumber to reap the rewards. But the rate at which the microbes process the carbon and release it into the atmosphere depends on the composition of soil organic matter, which varies depending on the subsurface’s mineralogy. Getting a handle on the thousands of molecules that live in the soil has until recently been considered too daunting to attempt, according to Hess.
“The typical view of carbon in soil is that it’s a mess: just gunky molecules all glommed together like overcooked spaghetti,” says Hess. “Most scientists have just given up on trying to do any molecular characterization.” However, at EMSL, researchers are finding that through the use of high resolution techniques such as FT-ICR, the molecular secrets of Arctic permafrost carbon are finally being told.
As part of the DOE’s Office of Biological and Environmental Research-funded Next-Generation Ecosystem Experiments in the Arctic, which seeks to understand the decomposition rates and pathways of carbon in permafrost soils, scientists will use FT-ICR mass spectrometry to dissect the molecular makeup of samples extracted across the Arctic. Baohua Gu of Oak Ridge National Laboratory is heading the biogeochemistry effort on soil organic matter.
“By identifying and quantifying the key soil organic carbon precursors to microbial production of small organics and/or byproducts, we can elucidate degradation pathways and contributions of soil organic matter in greenhouse gas production under future climate scenarios,” says Gu.
He hopes the new information will lead to improved climate modeling, allowing for more accurate predictions on the feedback of greenhouse gases in a warming climate. Alongside EMSL scientists, Gu also hopes to learn how carbon release and changing climate will affect the biological transformation of inorganic mercury, an abundant pollutant that accumulates in arctic soil, into its neurotoxic form, methylmercury. Subsurface microbes catalyze the toxic conversion. Gu and his colleagues plan to measure and identify specific organic thiols, molecules thought to form a strong molecular bridge between microbes and mercury that influences the poisonous switch. What they find there could allow researchers to gauge potential health impacts of mercury and its global cycling as the planet warms.
Upscaling
One difficult challenge micromodelers of all forms face at some point is how to translate their findings up to environmentally relevant scales. “The problem is an obvious one,” says Tim Scheibe, a scientist at Pacific Northwest National Laboratory. “If we resolve things at a micron scale, how big a chunk of the earth can we actually simulate?” As of now, the answer to his question is about 2,000 cubic centimeters (the size of a laboratory column), “and that’s really pushing it,” Scheibe says. He uses supercomputer models to simulate processes such as contaminant transport at the pore scale, then attempts to ramp them up to larger scales.
While researchers will never be able to model kilometer-size sites at the pore scale (a feat Scheibe jokes would require “a million supercomputers”), they can get closer by employing efficient computing. To connect fundamental insights learned from pore-scale models up to meaningful magnitudes, Scheibe is working on what he calls “hybrid multiscale models.”
“The idea is that we directly connect the pore-scale model with a coarser model,” Scheibe says. The simulation then goes back and forth between scales, iteratively feeding information garnered from one scale into the other.
Scheibe also collaborates with researchers to incorporate data into pore-scale models that goes beyond just minerals and contaminants. Including information from the genome sequences of microbes known to live in the subsurface has informed Scheibe’s models of processes such as uranium bioremediation. Iron- and sulfur-reducing microbes such as native Geobacter species interact with natural minerals in the subsurface to create conditions under which uranium precipitates out of solution and becomes immobilized. With the aid of supercomputer simulations, Scheibe and colleagues have created models that account for the flexibility of microbes to regulate their metabolic processes in response to environmental conditions.
The fundamental insights EMSL scientists and users gain from zooming into the dynamic molecular events that make up the pore-scale world may help inform the decisions of engineers and policy makers.
“We can use this molecular information to understand where crops should be planted, how much sea level will rise, and where cities should be,” says Hess. “EMSL’s role is at the molecular level, yet it informs models at a much higher scale.”
Note : The above story is based on materials provided by Environmental Molecular Sciences Laboratory
UAVSAR measurement, called an interferogram, of quiet movement on the Superstition Hills Fault after a 2010 Baja California earthquake, overlaid on a Google Earth image. Credit: NASA/JPL/USGS/California Geological Survey/Google
A new NASA study finds that a major 2010 earthquake in northern Mexico triggered quiet, non-shaking motions on several Southern California faults that released as much energy as a magnitude 4.9 to 5.3 earthquake.
The quiet motion associated with the widely felt, magnitude 7.2 earthquake centered in northern Baja California in Mexico, in April 2010 was discovered in before-and-after radar images of the region made by a NASA airborne instrument that produces extremely accurate maps of Earth motions. The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), which flies on a NASA C-20A aircraft from NASA’s Armstrong Flight Research Center facility in Palmdale, Calif., allows scientists to see how locations on Earth’s surface change between repeat flights over the same spot.
“It’s a new way of seeing the earthquake cycle,” said Andrea Donnellan of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., who led the study, published recently in the journal Geochemistry, Geophysics, Geosystems. “If we had been relying only on seismometers, we wouldn’t have known the extent to which these California faults were active.” Quiet, or aseismic, movement in faults doesn’t shake the ground, so it isn’t recorded by seismometers, which are typically used to study earthquakes.
UAVSAR measurements north of the 2010 El Mayor-Cucapah earthquake, which scientists have learned was followed by quiet movement on faults in California. Inset map shows the region on the California-Mexico border. Credit: NASA/JPL/USGS/California Geological Survey/Google
The 2010 El Mayor-Cucapah quake area is at the transition between spreading faults in the Gulf of California and sliding faults (called transform faults) where the Pacific and North American plates grind past each other along the West Coast. “The Earth is hot and soft there, and the plate boundary is still sorting itself out,” Donnellan said. The region is scored by roughly parallel faults running northwest-southeast, which are linked by short, crosswise faults.
Donnellan’s study focused on the parallel Imperial and Superstition Hills faults and the crosswise East Elmore Ranch fault. The UAVSAR measurements show that the Imperial fault slipped 1.4 inches (36 millimeters) along its entire length of 19 miles (30 kilometers). The Superstition Hills fault, about 16 miles (25.5 kilometers) long, slipped 0.6 inches (14 millimeters). The short East Elmore Ranch fault slipped 0.4 inches (9 millimeters).
In 2009, Donnellan and her colleagues chose this and two other California regions for UAVSAR observations because a JPL earthquake model targeted them as high-risk spots for a major earthquake. They also targeted the La Habra, California area, site of the recent March 28 magnitude 5.1 quake. Donnellan is following up with UAVSAR flights there as well to understand the motions related to that earthquake.
“Large, diffuse areas of slip are hard to document in the field, but they show up in UAVSAR images,” she said.
These UAVSAR flights are part of a larger NASA-led effort to regularly monitor crustal deformation throughout much of California in order to better understand geologic hazards such as earthquakes, volcanoes, landslides and sinkholes. The UAVSAR data complement that obtained from spaceborne instruments and help NASA design more effective satellite observatories for global application.
Note : The above story is based on materials provided by NASA
A 300-m-high fountain during episode 8 of the 1959 Kilauea Iki eruption from close to the Byron Ledge overlook. 7 am (HST) on 11 December 1959. Credit: Hawaiian Volcano Observatory, U.S. Geological Survey
Kīlauea volcano, on the Big Island of Hawai’i, typically has effusive eruptions, wherein magma flows to create ropy pāhoehoe lava, for example. However, Kīlauea less frequently erupts more violently, showering scoria and blocks over much of the surface of the island. To explain the variability in Kīlauea’s eruption styles, a team including Bruce Houghton, the Gordon Macdonald Professor of Volcanology in Geology and Geophysics at the University of Hawai’i at Mānoa (UHM) School of Ocean and Earth Science and Technology (SOEST) and colleagues from the University of Cambridge (UC) and Don Swanson from the Hawaiian Volcano Observatory (HVO) of the U.S. Geological Survey analyzed 25 eruptions that have taken place over the past 600 years.
The team’s research shows that the ultimate fate of a magma at Kīlauea, that is if the eruption will be effusive or explosive, is strongly influenced by the variability in composition of the deep magma — with more gas-rich magmas producing more explosive eruptions. “Gas-rich magmas are ‘predisposed’ to rise quickly through the Earth’s mantle and crust and erupt powerfully,” Houghton explained.
One of the biggest challenges in volcanic forecasting is to predict at an early stage the full path that an eruption will follow. Monitoring gives scientists an indication where an eruption will occur but not always the probable form it will take.
“Other statistics like a volcano’s volume, eruption rate, and duration are keys to real-time hazard and risk mapping,” said Houghton. “They are the target of approaches like ours.”
This investigation, published this week in Nature Geoscience, required careful analysis of the physical and chemical properties of eruption products over the last 600 years. Swanson and Houghton supplied a framework of very well-characterized eruptions using a detailed classified scheme for the size and power of the eruptions. UC performed nano-scale measurements of the original gas content of the magmas as ‘frozen’ in tiny packets of chilled melt inside large crystals in the magma.
This new look at the eruption history at Kīlauea has led to new understanding of what causes eruption style there. “Pre-existing wisdom had it that the form of an eruption was principally decided during the last kilometer of rise towards the surface. But now we know the content of dissolved gas at the deep source is a key,” said Houghton.
In the future, Houghton and colleagues hope to offer even more accurate models by estimating just how fast magma does rise at Kīlauea prior to eruption by using the rates at which the trapped original gasses can ‘leak’ out of the trapped magma.
Note : The above story is based on materials provided by University of Hawaii ‑ SOEST.
The physical environment can produce sudden shocks to the life of our planet through impacting space rocks, erupting volcanoes and other events.
But sometimes life itself turns the tables and strikes a swift blow back to the environment. New research suggests that the biggest extinction event on record may have been initiated by a small, but significant change to a tiny microbe.
The end-Permian (or PT) extinction event occurred 252 million years ago. It is often called the Great Dying because around 90 percent of marine species disappeared in one fell swoop. Similar numbers died on land as well, producing a stark contrast between Permian rock layers beneath (or before) the extinction and the Triassic layers above. Extinctions are common throughout time, but for this one, the fossil record truly skipped a beat.
“The end-Permian is the greatest extinction event that we know of,” said Daniel Rothman, a geophysicist at the Massachusetts Institute of Technology. “The changes in the fossil record were obvious even to 19th Century geologists.”
Understanding the cause of this biological devastation requires understanding the geochemical clues that go along with it. Chief among these clues is a sudden swing in the balance of carbon isotopes stored in rocks from that same time period.
If geologists can find what disrupted the carbon, they’ll likely know what killed off so much of the Earth’s life forms. Several theories have tried to explain the carbon perturbation as, for example, massive volcanism, or a drop in sea level, but none of these environmental causes have fully matched the data.
Rothman and his colleagues have identified a different culprit—one coming from biology rather than geology. They argue in the Proceedings of the National Academy of Sciences that the carbon disruption and, consequently, the end-Permian extinction were set off by a particular microorganism that evolved a new way to digest organic material into methane.
With this genetic innovation, these methane-producers, or methanogens, ran rampant across the ocean, overturning the carbon cycle. The resulting changes in ocean chemistry would have driven many species to extinction.
“This shows how unstable Earth’s systems are,” Rothman said. “A very small event in the microbial community can have an enormous impact on the environment.”
Carbon exchange
The basis of this new theory comes from a reassessment of the carbon data.
For decades, geologists have been aware that the ratio of carbon isotopes (the light verses heavy forms of the element) changed abruptly in geological samples around the time of the end-Permian event. Specifically, the carbon stored in rocks tilted towards the lighter isotope by about 1 percent over a matter of 100,000 years.
Rothman and his colleagues re-analyzed these isotope fluctuations, incorporating them into a model of dynamical exchange between different reservoirs of carbon material. The results showed that the level of carbon dioxide in the ocean rose faster than exponentially. The increase was slow at first, but picked up pace as time went on.
Rothman and his collaborators argue that no geological source can adequately explain the dramatic growth of carbon dioxide. One popular theory has been that high levels of carbon dioxide were released by massive volcanic eruptions in Siberia, which lasted for a million years and covered a million square miles with lava.
“It’s hard to get the arithmetic right with just volcanoes,” Rothman said.
He and his fellow authors believe an additional input is needed – one coming from biology. A burst in biological activity could explain the exponential-like growth in the ocean’s carbon dioxide reserve.
Success breeds success
Exponential-like growth is not uncommon in biology. Certain invasive species, for example, experience population explosions once they enter a new ecosystem. Similar types of expansion can occur when an evolutionary development gives a particular species a leg up on its competition.
The authors contend that some sort of biological innovation altered the distribution of carbon in the ocean. And they assume that the ocean was, in some sense, waiting for this innovation with a large reservoir of organic material (the detritus from dead organisms) in the ocean sediment.
“Other research has shown that during the end Permian, these organic products had accumulated to very high levels, probably due to a slowdown of normal degradation,” said Greg Fournier, a co-author also from MIT.
This organic sediment was like “a big pile of food” for an enterprising organism to exploit.
Fournier had a clue as to what sort of organism this might be. From previous work he had done as a NASA Astrobiology Institute (NAI) postdoctoral fellow, he knew that a major innovation occurred around this time period in a type of methane-spewing archaea called Methanosarcina.
This methanogen is currently found all over the place, Fournier says, with species inhabiting marine and freshwater sediments, soils, sewage, and even inside the guts of animals such as cattle, where they produce a lot of the methane released into the world.
Part of Methanosarcina’s success is due to the fact that these organisms can process acetate, a common organic residue, faster than some of their methanogen cousins. Basically, the Methanosarcina are able to get more energy out of the conversion of acetate to methane.
Fournier had earlier shown that Methanosarcina had acquired this ability from horizontal gene transfer. In some long-ago microbial tryst, an ancient methanogen (which produced methane as waste) swapped genes with an ancient cellulose-eating bacterium (which produced acetate as waste). This genetic “technology transfer” created an organism that could more efficiently metabolize acetate.
To obtain a more precise date for when this microbial innovation happened, Fournier and his colleagues performed a rigorous genetic analysis.
“We compared genomes from a variety of different methanogens and dated the evolution of this [new metabolic pathway] by using a calibrated ‘clock’ that counts the changes accumulated in genes over time,” Fournier said.
The results placed the gene-swapping event at 240 million years ago, plus or minus 40 million years.
“The molecular clock analysis simply confirms that, to the best of our ability to measure, the timing is consistent with [the end-Permian event],” Fournier said.
If indeed the genetic innovation occurred in the late Permian, then it’s reasonable to assume that the Methanosarcina population began to multiply. Much of the methane produced by these organisms would have converted—through oxidation reactions or biological processing—into carbon dioxide, causing a rise in the carbon dioxide levels of the ocean.
The conversion of methane into carbon dioxide would have had a secondary effect as well: it would have driven down the amount of oxygen in the ocean water. Because Methanosarcina is anaerobic, the reduction in oxygen would have helped them thrive even more, creating a positive feedback loop. This could explain the faster than exponential growth in carbon dioxide concentrations that the authors observed.
As previous scientists have argued, the high levels of carbon dioxide would have led to a more acidic ocean, which would have been especially deadly for shell-bearing lifeforms. And like a house of cards, many other species followed suit.
A nickel’s worth
One possible sticking point is that exponential-like growth often gets ahead of itself and becomes a victim of its own success. In biology, overgrown populations tend to run out of food or some other resource.
In the case of methanogens, this limiting resource might have been the element nickel, which these organisms need to produce metabolic enzymes. The levels of nickel in the ocean are not typically very high.
“If methanogens were to become active, they could be limited by nickel,” Rothman said.
However, when the team checked nickel concentrations in late Permian geological samples, they found a spike that corresponded with the carbon isotope fluctuations. The source of this high nickel abundance was most likely the massive volcanic activity in Siberia, where the world’s largest nickel deposits are located. That spike in nickel allowed methanogens to take off.
“It’s a nice confirmation because it closes a circle, so to speak, by bringing the story back to volcanism,” Rothman said.
Who gets the blame finally?
“It is a novel idea that will need a lot of testing to see if it has ‘legs’,” said geologist David Bottjer of the University of Southern California, who was not involved with this work.
The arguments seem valid to him, but it will take some time for “the process of science to unwind as we see how this new idea stands up to earlier proposed mechanisms.”
Rothman said they are currently studying whether the methanogens may have left some sort of biomarker, for example an organic compound, which could provide further support for the scenario.
A photo of the Permian Triassic (PT) boundary at Meishan, China. Credit: Shuzhong Shen
“[The authors] have done a really nice job linking the latest geo-chronologic age constraints on the duration of the extinction to the changes in the carbon cycle,” said paleontologist Douglas Erwin of the Smithsonian Institution.
But Erwin thinks the emphasis on methanogens is misplaced.
“Their suggestion that the PT [extinction] was instigated by a ‘specific microbial innovation’ suggests a misunderstanding of causality,” he said.
To his thinking, volcanism is the ultimate cause, since it triggered the methanogen growth by creating favorable conditions.
Rothman admits that’s one way to look at it, but he doesn’t think the volcanoes (and their release of nickel) were necessary for the explosive microbial growth. Instead, he calls the volcanism a “catalytic event” that helped propel the genetic innovation.
“There is a random component to biological evolution,” said Fournier. “This gene transfer occurs by chance, but is only selected for and expands through a population when it conveys a specific advantage, which would be realized under those conditions [brought on by the volcanism].”
Either way, it’s impressive how interdependent all these different elements appear to have been.
“The clear implication is that life and the environment have co-evolved,” Rothman said.
Note : The above story is based on materials provided by Astrobio net
Chemical Formula: CaFe2+2Fe3+(Si2O7)O(OH) Locality: Capo Calamita, on Elba. Name Origin: Named ilvaite from the Latin name of the island of Elba.
Ilvaite is a sorosilicate of iron and calcium with formula: CaFe2+2Fe3+(Si2O7)O(OH). Both manganese and magnesium substitute in the structure. Ilvaite crystallizes in the orthorhombic system in black prismatic crystals and columnar masses. It is black to brownish black to gray and opaque. It has a Mohs hardness of 5.5 to 6 and a specific gravity of 3.8 to 4.1. Ilvaite is structurally related to lawsonite.
It occurs in contact metamorphic rocks and skarn ore deposits. It also occurs less commonly in syenites.
Ilvaite was first described in 1811 on the island of Elba and the name ilvaite from the Latin name ilva of the island. Sometimes referred to as yenite.
Physical Properties
Cleavage: {010} Distinct, {001} Distinct Color: Iron black, Dark grayish black. Density: 3.99 – 4.05, Average = 4.01 Diaphaneity: Opaque Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern. Hardness: 5.5-6 – Knife Blade-Orthoclase Luminescence: Non-fluorescent. Luster: Sub Metallic Streak: brownish black
First image taken by the Mars Color Camera aboard India’s Mars Orbiter Mission (MOM) spacecraft while orbiting Earth and before the Trans Mars Insertion firing on Dec. 1, 2013. Image is focused on the Indian subcontinent. Credit: ISRO
While astronomers are trying to figure out which planets they find are habitable, there are a range of things to consider. How close are they to their parent star? What are their atmospheres made of? And once those answers are figured out, here’s something else to wonder about: how many minerals are on the planet’s surface?
In a talk today, the Carnegie Institution of Washington’s Robert Hazen outlined his findings showing that two-thirds of minerals on Earth could have arisen from life itself. The concept is not new—he and his team first published on that in 2008—but his findings came before the plethora of exoplanets discovered by the Kepler space telescope.
As more information is learned about these distant worlds, it will be interesting to see if it’s possible to apply his findings—if we could detect the minerals from afar in the first place.
“We live on a planet of remarkable beauty, and when you look at it from the proximity of our moon, you see what is obviously a very dynamic planet,” Hazen told delegates at “Habitable Worlds Across Time and Space”, a spring symposium from the Space Telescope Science Institute that is being webcast this week (April 28-May 1).
His point was that planets don’t necessarily start out that way, but he said in his talk that he’d invite comments and questions on his work for alternative processes. His team believes that minerals and life co-evolved: life became more complex and the number of minerals increased over time.
The first mineral in the cosmos was likely diamonds, which were formed in supernovas. These star explosions are where the heavier elements in our cosmos were created, making the universe more rich than its initial soup of hydrogen and helium.
There are in fact 10 elements that were key in the Earth’s formation, Hazen said, as well as that of other planets in our solar system (which also means that presumably these would apply to exoplanets). These were carbon, nitrogen, oxygen, magnesium, silicon, carbon, titanium, iron and nitrogen,which formed about a dozen minerals on the early Earth.
Here’s the thing, though. Today there are more than 4,900 minerals on Earth that are formed from 72 essential elements. Quite a change.
Hazen’s group proposes 10 stages of evolution:
Primary chondrite minerals (4.56 billion years ago) – what was around as the solar nebula that formed our solar system cooled. 60 mineral species at this time.
Planetesimals—or protoplanets—changed by impacts (4.56 BYA to 4.55 BYA). Here is where feldspars, micas, clays and quartz arose. 250 mineral species.
Planet formation (4.55 BYA to 3.5 BYA). On a “dry” planet like Mercury, evolution stopped at about 300 mineral species, while “wetter” planets like Mars would have seen about 420 mineral species that includes hydroxides and clays produced from processes such as volcanism and ices.
Granite formation (more than 3.5 BYA). 1,000 mineral species including beryl and tantalite.
Plate tectonics (more than 3 BYA). 1,500 mineral species. Increases produced from changes such as new types of volcanism and high-pressure metamorphic changes inside the Earth.
These stages above are about as far as you would get on a planet without life, Hazen said. As for the remaining stages on Earth, here they are:
Anoxic biosphere (4 to 2.5 BYA), again with about 1,500 mineral species existing in the early atmosphere. Here was the rise of chemolithoautotrophs, or life that obtains energy from oxidizing inorganic compounds.
Paleoproterozoic oxidation (2.5 to 1.5 BYA)—a huge rise in mineral species to 4,500 as oxygen becomes a dominant player in the atmosphere. “We’re trying to understand if this is really true for every other planet, or if there is alternative pathways,” Hazen said.
It should be noted here that oxygen does not necessarily indicate there is complex life. Fellow speaker David Catling from the University of Washington, however, noted that oxygen rose in the atmosphere about 2.4 billion years ago, coincident with the emergence of complex life.
Animals as we understand them could have been “impossible for most of Earth’s history because they couldn’t breathe,” he noted. But more study will be needed on this point. After all, we’ve only found life on one planet: Earth.
Note : The above story is based on materials provided by Universe Today
The U.S. Geological Survey captured the upper parts of the landslide in Oso, Wash., in an aerial survey taken five days after this natural disaster killed 41 people. “Active” search and rescue efforts were suspended this week as the community turned its attention to debris removal. Credit: Jonathan Godt, USGS
Mudslides. Landslides. Volcanic debris flows. Avalanches. Falling rocks. They can come along so suddenly that people, homes, roads and even towns are buried or destroyed without much warning. Recently, we’ve had dramatic reminders of this, such as the mudslide in Oso, Wash., where 41 people died; an avalanche on Mt. Everest that killed 13 experienced Sherpas and another landslide event in Jackson, Wyo. And as much as ancient Pompeii serves as the most dramatic, historic reminder of the incredible element of surprise these events can wield, what seems extraordinarily incalculable is becoming…well, calculable.
Maybe that doesn’t seem so surprising on the surface as one reminisces about math story problems of long ago, such as, “if an avalanche flow is moving at a rate of 50 meters per second, how long will it take to swallow up a village located 30 kilometers away?” Unfortunately, for geologists and others involved in these issues, the particulars make the solution far from simple algebra.
Earthen, volcanic and snowy materials—all of which can move quickly downhill—do so at varying rates depending on their composition, the composition of the geological features over which they flow, and the weather. The benefit to building forecasting models—showing how the earthen materials are prone to move and where they might go post-volcano or during a particularly wet spring—is that they can assist policymaking, urban planning, insurance risk assessment and, most importantly, public safety risk reduction.
One National Science Foundation (NSF)-funded mathematician, E. Bruce Pitman from the University of Buffalo, has been modeling the dynamics of flowing granular materials since 2001 when engineering and geology colleagues came together to start estimating volcanic flow.
“You see these wonderful volcanic eruptions with the plumes, but gravity currents are going down the mountain even as all this stuff is going up into the air,” Pitman said. “It can be very deadly. And depending on the mountain—if there’s snow on the mountain—then you have this muddy sort of muck, so it can go even faster downhill.”
Volcanic flows and mudslides are examples of what geoscientists call “gravity currents.”
According to the Centers for Disease Control and Prevention, “landslides and debris flows result in 25 to 50 deaths each year” in the United States. The U.S. Geological Survey (USGS) reports that “all 50 states and the U.S. territories experience landslides and other ground-failure problems,” including 36 states with “moderate to highly severe landslide hazards,” which include the Appalachian and Rocky Mountains, Pacific Coast regions and Puerto Rico.
USGS notes that areas denuded because of wildfires or overdevelopment are particularly vulnerable to the whims of what’s termed generally as “ground failures.”
Pitman has spent the past 13 years studying the flows of the Soufrière Hills volcano on Montserrat, the Colima volcano west of Mexico City and the Ruapehu volcano in New Zealand, among other sites. Working with an engineer whose expertise is in high performance computing, statisticians and several geologists, Pitman studies geophysical mass flows, specifically volcanic avalanches and pyroclastic (hot gas and rock) flows, which are “dry” flows.
“We started modeling volcanic flows as dry volcanic flows, so the equation described the material as each particle frictionally sliding over the next particle,” Pitman said. “However, we knew it wasn’t only solid particles. There could be air or water too, so we developed another model. This naturally makes the analysis harder. In mudslides, you have to factor in mud, which is a viscoplastic fluid—partly like a fluid but also able to deform like a plastic material and never rebound. In wet or dry materials, you can make some reasonable predictions because flow is more or less the same. It is much harder to do that with mud.”
Pitman explained the way a mathematician works to develop a predictive model of a landslide.
“There are three questions,” he said. “First, is something going to happen? That is notoriously difficult—what’s going on under the ground? Where’s the water table? How much moisture is in the soil? What’s the structure of the soil? Since we can’t look under the ground, we have to make all kinds of assumptions about the ground, which poses difficulties.
“Secondly, if a slide were to occur, what areas are at risk? That’s something that with a math model you can hope to explain. OK, is the east, west, north or south slope going to slip? How large a flow? Which areas downstream are at risk?
“Lastly, you have to ask what part of the model do you most care about. This helps you to simplify the modeling. Then you run the what-if scenarios to determine the greatest risk. Is it an area at risk and do mudslides happen regularly?”
According to Michael Steuerwalt, an NSF Division of Mathematical Sciences program director, many would be inclined to think that lava flows are far more complicated to model because of the issues of heat and explosive force. However, a mix of dramatically different particle sizes and shapes—which range from dirt grains to people, cars, houses, boulders and trees—can considerably complicate a slide model.
“If you’re trying to deduce, for example, where under this mudslide is the house that used to be way up there (along with its inhabitants), then the model is very complicated indeed,” Steuerwalt said. “Math won’t solve this problem alone, either. But with topographic data, soil data and predictions of precipitation, one could make assessments of where not to build and estimates of risk. This really is an opportunity for mathematicians coupled not only with statisticians, but also with geographers, geoscientists and engineers.”
Ultimately, the process needs good data. But it is also about understanding where the model has simplified the equation and created “errors.”
“This may sound odd, but it’s not about developing the perfect model,” Pitman said. “All models have errors in them because we make simplifications to wrap our brains around the physical processes at work. The key is quantifying those errors.”
So, essentially the mathematician has to know where to simplify the equation, and that too comes with his collaborative approach and working with other experts, such as volcanologists, and then interfacing with public safety officials.
For a guy who “hated” math in the fifth grade and majored in physics initially in college, this work has turned into something he loves, but also something where he feels he makes a difference.
“I love how this work stretches me and my ability to understand other fields,” he said. “I get to explore what interests them and what just might be the little hook that allows me to pry apart a problem.”
Note : The above story is based on materials provided by National Science Foundation
Chemical Formula:FeTiO
3 Locality: Ilmen Mountains, southern Urals, of the Russia. Name Origin: Named after It’s locality.
Ilmenite is the titanium-iron oxide mineral with the idealized formula FeTiO
3. It is a weakly magnetic black or steel-gray solid. From the commercial perspective, ilmenite is the most important ore of titanium.
Structure and properties
Ilmenite crystallizes in the trigonal system. The ilmenite crystal structure consists of an ordered derivative of the corundum structure; in corundum all cations are identical but in ilmenite Fe2+ and Ti4+ ions occupy alternating layers perpendicular to the trigonal c axis. Containing high spin ferrous centers, ilmenite is paramagnetic.
Ilmenite is commonly recognized in altered igneous rocks by the presence of a white alteration product, the pseudo-mineral leucoxene. Often ilmenites are rimmed with leucoxene, which allows ilmenite to be distinguished from magnetite and other iron-titanium oxides. The example shown in the image at right is typical of leucoxene-rimmed ilmenite.
In reflected light it may be distinguished from magnetite by more pronounced reflection pleochroism and a brown-pink tinge.
Samples of ilmenite exhibit a weak response to a hand magnet.
Physical Properties
Cleavage: None Color: Iron black, Black. Density: 4.72 Diaphaneity: Opaque Fracture: Conchoidal – Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz). Hardness: 5-5.5 – Apatite-Knife Blade Luminescence: Non-fluorescent. Luster: Sub Metallic Magnetism: Naturally weak Streak: brownish black
The Oligocene is a geologic epoch of the Paleogene period and extends from about 33.9 million to 23 million years before the present (33.9±0.1 to 23.03±0.05 Ma). As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly uncertain. The name Oligocene comes from the Greek ὀλίγος (oligos, few) and καινός (kainos, new), and refers to the sparsity of additional modern mammalian species of fauna after a burst of evolution during the Eocene. The Oligocene is preceded by the Eocene epoch and is followed by the Miocene epoch. The Oligocene is the third and final epoch of the Paleogene period.
The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included a global expansion of grasslands, and a regression of tropical broad leaf forests to the equatorial belt.
The start of the Oligocene is marked by a notable extinction event called the Grande Coupure; it featured the replacement of European fauna with Asian fauna, except for the endemic rodent and marsupial families. By contrast, the Oligocene–Miocene boundary is not set at an easily identified worldwide event but rather at regional boundaries between the warmer late Oligocene and the relatively cooler Miocene.
Subdivisions
Oligocene faunal stages from youngest to oldest are:
Chattian or Late Oligocene (28.1 – 23.03 mya)
Rupelian or Early Oligocene (33.9 – 28.1 mya)
Climate
The Paleogene period general temperature decline is interrupted by an Oligocene 7 million year stepwise climate change. A deeper 8.2 °C, 400,000 year temperature depression leads the 2 °C, 7 million year stepwise climate change 33.5 Ma (Million years ago). The stepwise climate change began 32.5Ma and lasted through to 25.5Ma, as depicted in the PaleoTemps chart. The Oligocene climate change was a global increase in ice volume and a 55 M (181 feet) decrease in sea level (35.7-33.5 Ma) with a closely related (25.5–32.5 Ma) temperature depression. The 7 million year depression abruptly terminated within 1–2 million years of the La Garita Caldera eruption at 28-26 Ma. A deep 400,000 year glaciated Oligocene Miocene boundary event is recorded at McMurdo Sound and King George Island.
This shows estimates of global average surface air temperature over the ~540 My of the Phanerozoic
Paleogeography
During this period, the continents continued to drift toward their present positions. Antarctica became more isolated and finally developed an ice cap.(Haines)
Mountain building in western North America continued, and the Alps started to rise in Europe as the African plate continued to push north into the Eurasian plate, isolating the remnants of the Tethys Sea. A brief marine incursion marks the early Oligocene in Europe. Marine fossils from the Oligocene are rare in North America. There appears to have been a land bridge in the early Oligocene between North America and Europe, since the faunas of the two regions are very similar. Sometime during the Oligocene, South America was finally detached from Antarctica and drifted north towards North America. It also allowed the Antarctic Circumpolar Current to flow, rapidly cooling the Antarctic continent.
Flora
Angiosperms continued their expansion throughout the world as tropical and sub-tropical forests were replaced by temperate deciduous forests. Open plains and deserts became more common and grasses expanded from their water-bank habitat in the Eocene moving out into open tracts. However, even at the end of the period grass was not quite common enough for modern savannas.(Haines)
In North America, subtropical species dominated with cashews and lychee trees present, and temperate trees such as roses, beeches, and pines were common. The legumes spread, while sedges, bulrushes, and ferns continued their ascent.
Fauna
Important Oligocene land fauna are found on all continents at this time. Even more open landscapes allowed animals to grow to larger sizes than they had earlier in the Paleogene. Marine faunas became fairly modern, as did terrestrial vertebrate fauna on the northern continents. This was probably more as a result of older forms dying out than as a result of more modern forms evolving. Many groups, such as horses, entelodonts, rhinoceroses, oreodonts, and camels, became more able to run during this time, adapting to the plains that were spreading as the Eocene rainforests receded. The first felid, Proailurus, originated in Asia during the late Oligocene and spread to Europe.
South America was isolated from the other continents and evolved a quite distinct fauna during the Oligocene. The South American continent became home to strange animals such as pyrotheres and astrapotheres, as well as litopterns and notoungulates. Sebecosuchian crocodiles, terror birds, and carnivorous marsupials, like the borhyaenids remained the dominant predators. Brontotheres died out in the Earliest Oligocene, and creodonts died out outside Africa and the Middle East at the end of the period. Multituberculates, an ancient lineage of primitive mammals, also went extinct in the Oligocene. The Oligocene was home to a wide variety of strange mammals. A good example of this would be in the White River Badlands of North America, which were formerly a semi-arid prairie home to many different types of endemic mammals, including entelodonts like Archaeotherium, camels (such as Poebrotherium), running rhinos, three-toed horses (such as Mesohippus), nimravids, protoceratids, and early dogs like Hesperocyon. Oreodonts, an endemic American group, were very diverse during this time. In Asia during the Oligocene, a group of running rhinos gave rise to the indricotheres, like Indricotherium, which were the largest land mammals ever to walk the Earth.
The marine animals of Oligocene oceans resembled today’s fauna, such as the bivalves. Calcareous cirratulids appeared in the Oligocene. The fossil record of marine mammals is a little spotty during this time, and not as well known as the Eocene or Miocene, but some fossils have been found. The baleen and toothed cetaceans, or whales, had just appeared, and their ancestors, the archaeocete cetaceans began to decrease in diversity due to their lack of echolocation, which was very useful as the water became colder and cloudier. Other factors to their decline could include climate changes and competition with today’s modern cetaceans and the carcharhinid sharks, which also appeared in this epoch. Early desmostylians, like Behemotops, are known from the Oligocene. Pinnipeds probably appeared near the end of the epoch from a bear-like or otter-like ancestor.
Oceans
The Oligocene sees the beginnings of modern ocean circulation, with tectonic shifts causing the opening and closing of ocean gateways. Cooling of the oceans had already commenced by the Eocene/Oligocene boundary, and they continued to cool as the Oligocene progressed. The formation of permanent Antarctic ice sheets during the early Oligocene and possible glacial activity in the Arctic may have influenced this oceanic cooling, though the extent of this influence is still a matter of some significant dispute.
The effects of oceanic gateways on circulation
The opening and closing of ocean gateways: the opening of the Drake Passage; the opening of the Tasmanian Gateway and the closing of the Tethys seaway; along with the final formation of the Greenland–Iceland–Faroes sill; played vital parts in reshaping oceanic currents during the Oligocene. As the continents shifted to a more modern configuration, so too did ocean circulation.
The Drake Passage
The Drake Passage is located between South America and Antarctica. Once the Tasmanian Gateway between Australia and Antarctica opened, all that kept Antarctica from being completely isolated by the Southern Ocean was its connection to South America. As the South American continent moved north, the Drake Passage opened and enabled the formation of the Antarctic Circumpolar Current (ACC), which would have kept the cold waters of Antarctica circulating around that continent and strengthened the formation of Antarctic Bottom Water (ABW). With the cold water concentrated around Antarctica, sea surface temperatures and, consequently, continental temperatures would have dropped. The onset of Antarctic glaciation occurred during the early Oligocene, and the effect of the Drake Passage opening on this glaciation has been the subject of much research. However, some controversy still exists as to the exact timing of the passage opening, whether it occurred at the start of the Oligocene or nearer the end. Even so, many theories agree that at the Eocene/Oligocene (E/O) boundary, a yet shallow flow existed between South America and Antarctica, permitting the start of an Antarctic Circumpolar Current.
Stemming from the issue of when the opening of the Drake Passage took place, is the dispute over how great of an influence the opening of the Drake Passage had on the global climate. While early researchers concluded that the advent of the ACC was highly important, perhaps even the trigger, for Antarctic glaciation and subsequent global cooling, other studies have suggested that the δ18O signature is too strong for glaciation to be the main trigger for cooling. Through study of Pacific ocean sediments, other researchers have shown that the transition from warm Eocene ocean temperatures to cool Oligocene ocean temperatures took only 300,000 years, which strongly implies that feedbacks and factors other than the ACC were integral to the rapid cooling.
The Late Oligocene opening of the Drake Passage
The latest hypothesized time for the opening of the Drake Passage is during the early Miocene. Despite the shallow flow between South America and Antarctica, there was not enough of a deep water opening to allow for significant flow to create a true Antarctic Circumpolar Current. If the opening occurred as late as hypothesized, then the Antarctic Circumpolar Current could not have had much of an effect on early Oligocene cooling, as it would not have existed.
The Early Oligocene opening of the Drake Passage
The earliest hypothesized time for the opening of the Drake Passage is around 30 Ma. One of the possible issues with this timing was the continental debris cluttering up the seaway between the two plates in question. This debris, along with what is known as the Shackleton Fracture Zone, has been shown in a recent study to be fairly young, only about 8 million years old. The study concludes that the Drake Passage would be free to allow significant deep water flow by around 31 Ma. This would have facilitated an earlier onset of the Antarctic Circumpolar Current.
Currently, an opening of the Drake Passage during the Early Oligocene is favored.
The opening of the Tasman Gateway
The other major oceanic gateway opening during this time was the Tasman, or Tasmanian, depending on the paper, gateway between Australia and Antarctica. The time frame for this opening is less disputed than the Drake Passage and is largely considered to have occurred around 34 Ma. As the gateway widened, the Antarctic Circumpolar Current strengthened.
The Tethys Seaway closing
Though the Tethys was not a gateway, but rather a sea in its own right. Its closing during the Oligocene had significant impact on both ocean circulation and climate. The collisions of the African plate with the European plate and of the Indian subcontinent with the Asian plate, cut off the Tethys seaway that had provided a low-latitude ocean circulation. The closure of Tethys built some new mountains (the Zagros range) and drew down more carbon dioxide from the atmosphere, contributing to global cooling.
Greenland–Iceland–Faroes
The gradual separation of the clump of continental crust and the deepening of tectonic sill in the North Atlantic that would become Greenland, Iceland, and the Faroe Islands helped to increase the deep water flow in that area. More information about the evolution of North Atlantic Deep Water will be given a few sections down.
Ocean cooling
Evidence for ocean-wide cooling during the Oligocene exists mostly in isotopic proxies. Patterns of extinction and patterns of species migration can also be studied to gain insight into ocean conditions. For a while, it was thought that the glaciation of Antarctica may have significantly contributed to the cooling of the ocean, however, recent evidence tends to deny this.
Deep water
Isotopic evidence suggests that during the early Oligocene, the main source of deep water was the North Pacific and the Southern Ocean. As the Greenland-Iceland-Faroe sill deepened and thereby connected the Norwegian–Greenland sea with the Atlantic Ocean, the deep water of the North Atlantic began to come into play as well. Computer models suggest that once this occurred, a more modern in appearance thermo-haline circulation started.
North Atlantic deep water
Evidence for the early Oligocene onset of chilled North Atlantic deep water lies in the beginnings of sediment drift deposition in the North Atlantic, such as the Feni and Southeast Faroe drifts
South Ocean deep water
The chilling of the South Ocean deep water began in earnest once the Tasmanian Gateway and the Drake Passage opened fully. Regardless of the time at which the opening of the Drake Passage occurred, the effect on the cooling of the Southern Ocean would have been the same.
Impact events
Recorded extraterrestrial impacts:
Nunavut, Canada (23 Ma, crater 24 km (15 mi) diameter,)
Supervolcanic explosions
La Garita Caldera (28 through 26 million years ago, VEI=9.2)The above story is based on materials provided by Wikipedia
The Eocene epoch, lasting from 56 to 33.9 million years ago, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the Grande Coupure (the “Great Break” in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay. As with other geologic periods, the strata that define the start and end of the epoch are well identified, though their exact dates are slightly uncertain.
The name Eocene comes from the Greek ἠώς (eos, dawn) and καινός (kainos, new) and refers to the “dawn” of modern (‘new’) fauna that appeared during the epoch.
Subdivisions
The Eocene epoch is usually broken into Early and Late, or—more usually—Early, Middle, and Late subdivisions. The corresponding rocks are referred to as Lower, Middle, and Upper Eocene. Of the stages shown above, the Ypresian and occasionally the Lutetian constitute the Early, the Priabonian and sometimes the Bartonian the Late state; alternatively, the Lutetian and Bartonian are united as the Middle Eocene.
Climate
The Eocene Epoch contained a wide variety of different climate conditions that includes the warmest climate in the Cenozoic Era and ends in an icehouse climate. The evolution of the Eocene climate began with warming after the end of the Palaeocene-Eocene Thermal Maximum (PETM) at 56 million years ago to a maximum during the Eocene Optimum at around 49 million years ago. During this period of time, little to no ice was present on Earth with a smaller difference in temperature from the equator to the poles. Following the maximum was a descent into an icehouse climate from the Eocene Optimum to the Eocene-Oligocene transition at 34 million years ago. During this decrease ice began to reappear at the poles, and the Eocene-Oligocene transition is the period of time where the Antarctic ice sheet began to rapidly expand.
Atmospheric greenhouse gas evolution
Greenhouse gases, in particular carbon dioxide and methane, played a significant role during the Eocene in controlling the surface temperature. The end of the PETM was met with a very large sequestration of carbon dioxide in the form of methane clathrate, coal, and crude oil at the bottom of the Arctic Ocean, that reduced the atmospheric carbon dioxide. This event was similar in magnitude to the massive release of greenhouse gasses at the beginning of the PETM, and it is hypothesized that the sequestration was mainly due to organic carbon burial and weathering of silicates. For the early Eocene there is much discussion on how much carbon dioxide is in the atmosphere. This is due to numerous proxies representing different atmospheric carbon dioxide content. For example, diverse geochemical and paleontological proxies indicate that at the maximum of global warmth the atmospheric carbon dioxide values were at 700 – 900 ppm while other proxies such as pedogenic (soil building) carbonate and marine boron isotopes indicate large changes of carbon dioxide of over 2,000 ppm over periods of time of less than 1 million years. Sources for this large influx of carbon dioxide could be attributed to volcanic out-gassing due to North Atlantic rifting or oxidation of methane stored in large reservoirs deposited from the PETM event in the sea floor or wetland environments. For contrast, today the carbon dioxide levels are at 400 ppm or .04%.
During the early Eocene, methane was another greenhouse gas that had a drastic effect on the climate. In comparison to carbon dioxide, methane has much higher consequences with regards to temperature as methane has ~23 times more effect per molecule than carbon dioxide on a 100-year scale (it has a higher global warming potential). The majority of the methane released to the atmosphere during this period of time would have been from wetlands, swamps, and forests. The atmospheric methane concentration today is 0.000179% or 1.79 ppmv. Due to the warmer climate and sea level rise associated with the early Eocene, more wetlands, more forests, and more coal deposits would be available for methane release. Comparing the early Eocene production of methane to current levels of atmospheric methane, the early Eocene would be able to produce triple the amount of current methane production. The warm temperatures during the early Eocene could have increased methane production rates, and methane that is released into the atmosphere would in turn warm the troposphere, cool the stratosphere, and produce water vapor and carbon dioxide through oxidation. Biogenic production of methane produces carbon dioxide and water vapor along with the methane, as well as yielding infrared radiation. The breakdown of methane in an oxygen atmosphere produces carbon monoxide, water vapor and infrared radiation. The carbon monoxide is not stable so it eventually becomes carbon dioxide and in doing so releases yet more infrared radiation. Water vapor, traps more infrared than does carbon dioxide.
The middle to late Eocene marks not only the switch from warming to cooling, but also the change in carbon dioxide from increasing to decreasing. At the end of the Eocene Optimum, carbon dioxide began decreasing due to increased siliceous plankton productivity and marine carbon burial. At the beginning of the middle Eocene an event that may have triggered or helped with the draw down of carbon dioxide was the Azolla event at around 49 million years ago. With the equable climate during the early Eocene, warm temperatures in the arctic allowed for the growth of azolla, which is a floating aquatic fern, on the Arctic Ocean. Compared to current carbon dioxide levels, these azolla grew rapidly in the enhanced carbon dioxide levels found in the early Eocene. As these azolla sank into the Arctic Ocean, they became buried and sequestered their carbon into the seabed. This event could have led to a draw down of atmospheric carbon dioxide of up to 470 ppm. Assuming the carbon dioxide concentrations were at 900 ppmv prior to the Azolla Event they would have dropped to 430 ppmv, or 40 ppmv more than they are today, after the Azolla Event. Another event during the middle Eocene that was a sudden and temporary reversal of the cooling conditions was the Middle Eocene Climatic Optimum. At around 41.5 million years ago, stable isotopic analysis of samples from Southern Ocean drilling sites indicated a warming event for 600 thousand years. A sharp increase in atmospheric carbon dioxide was observed with a maximum of 4000 ppm: the highest amount of atmospheric carbon dioxide detected during the Eocene. The main hypothesis for such a radical transition was due to the continental drift and collision of the India continent with the Asia continent and the resulting formation of the Himalayas. Another hypothesis involves extensive sea floor rifting and metamorphic decarbonation reactions releasing considerable amounts of carbon dioxide to the atmosphere.
At the end of the Middle Eocene Climatic Optimum, cooling and the carbon dioxide drawdown continued through the late Eocene and into the Eocene-Oligocene transition around 34 million years ago. Multiple proxies, such as oxygen isotopes and alkenones, indicate that at the Eocene-Oligocene transition, the atmospheric carbon dioxide concentration had decreased to around 750-800 ppm, approximately twice that of present levels.
Early Eocene and the equable climate problem
One of the unique features of the Eocene’s climate as mentioned before was the equable and homogeneous climate that existed in the early parts of the Eocene. A multitude of proxies support the presence of a warmer equable climate being present during this period of time. A few of these proxies include the presence of fossils native to warm climates, such as crocodiles, located in the higher latitudes, the presence in the high-latitudes of frost-intolerant flora such as palm trees which cannot survive during sustained freezes, and fossils of snakes found in the tropics that would require much higher average temperatures to sustain them. Using isotope proxies to determine ocean temperatures indicate sea surface temperatures in the tropics as high as 35 °C (95 °F) and bottom water temperatures that are 10 °C (18 °F) higher than present day values. With these bottom water temperatures, temperatures in areas where deep-water forms near the poles are unable to be much cooler than the bottom water temperatures.
An issue arises, however, when trying to model the Eocene and reproduce the results that are found with the proxy data. Using all different ranges of greenhouse gasses that occurred during the early Eocene, models were unable to produce the warming that was found at the poles and the reduced seasonality that occurs with winters at the poles being substantially warmer. The models, while accurately predicting the tropics, tend to produce significantly cooler temperatures of up to 20 °C (36 °F) underneath the actual determined temperature at the poles. This error has been classified as the “equable climate problem”. To solve this problem, the solution would involve finding a process to warm the poles without warming the tropics. Some hypotheses and tests which attempt to find the process are listed below.
Large lakes
Due to the nature of water as opposed to land, less temperature variability would be present if a large body of water is also present. In an attempt to try to mitigate the cooling polar temperatures, large lakes were proposed to mitigate seasonal climate changes. To replicate this case, a lake was inserted into North America and a climate model was run using varying carbon dioxide levels. The model runs concluded that while the lake did reduce the seasonality of the region greater than just an increase in carbon dioxide, the addition of a large lake was unable to reduce the seasonality to the levels shown by the floral and faunal data.
Ocean heat transport
The transport of heat from the tropics to the poles, much like how ocean heat transport functions in modern times, was considered a possibility for the increased temperature and reduced seasonality for the poles. With the increased sea surface temperatures and the increased temperature of the deep ocean water during the early Eocene, one common hypothesis was that due to these increases there would be a greater transport of heat from the tropics to the poles. Simulating these differences, the models produced lower heat transport due to the lower temperature gradients and were unsuccessful in producing an equable climate from only ocean heat transport.
Orbital parameters
While typically seen as a control on ice growth and seasonality, the orbital parameters were theorized as a possible control on continental temperatures and seasonality. Simulating the Eocene by using an ice free planet, eccentricity, obliquity, and precession were modified in different model runs to determine all the possible different scenarios that could occur and their effects on temperature. One particular case led to warmer winters and cooler summer by up to 30% in the North American continent, and it reduced the seasonal variation of temperature by up to 75%. While orbital parameters did not produce the warming at the poles, the parameters did show a great effect on seasonality and needed to be considered.
Polar stratospheric clouds
Another method considered for producing the warm polar temperatures were polar stratospheric clouds. Polar stratospheric clouds are clouds that occur in the lower stratosphere at very low temperatures. Polar stratospheric clouds have a great impact on radiative forcing. Due to their minimal albedo properties and their optical thickness, polar stratospheric clouds act similar to a greenhouse gas and traps outgoing longwave radiation. Different types of polar stratospheric clouds occur in the atmosphere: polar stratospheric clouds that are created due to interactions with nitric or sulfuric acid and water (Type I) or polar stratospheric clouds that are created with only water ice (Type II).
Methane is an important factor in the creation of the primary Type II polar stratospheric clouds that were created in the early Eocene. Since water vapor is the only supporting substance used in Type II polar stratospheric clouds, the presence of water vapor in the lower stratosphere is necessary where in most situations the presence of water vapor in the lower stratosphere is rare. When methane is oxidized, a significant amount of water vapor is released. Another requirement for polar stratospheric clouds is cold temperatures to ensure condensation and cloud production. Polar stratospheric cloud production, since it requires the cold temperatures, is usually limited to nighttime and winter conditions. With this combination of wetter and colder conditions in the lower stratosphere, polar stratospheric clouds could have formed over wide areas in Polar Regions.
To test the polar stratospheric clouds effects on the Eocene climate, models were run comparing the effects of polar stratospheric clouds at the poles to an increase in atmospheric carbon dioxide.The polar stratospheric clouds had a warming effect on the poles, increasing temperatures by up to 20 °C in the winter months. A multitude of feedbacks also occurred in the models due to the polar stratospheric clouds’ presence. Any ice growth was slowed immensely and would lead to any present ice melting. Only the poles were affected with the change in temperature and the tropics were unaffected, which with an increase in atmospheric carbon dioxide would also cause the tropics to increase in temperature. Due to the warming of the troposphere from the increased greenhouse effect of the polar stratospheric clouds, the stratosphere would cool and would potentially increase the amount of polar stratospheric clouds.
While the polar stratospheric clouds could explain the reduction of the equator to pole temperature gradient and the increased temperatures at the poles during the early Eocene, there are a few drawbacks to maintaining polar stratospheric clouds for an extended period of time. Separate model runs were used to determine the sustainability of the polar stratospheric clouds. Methane would need to be continually released and sustained to maintain the lower stratospheric water vapor. Increasing amounts of ice and condensation nuclei would be need to be high for the polar stratospheric cloud to sustain itself and eventually expand.
Hyperthermals through the Early Eocene
During the warming in the Early Eocene between 52 and 55 million years ago, there were a series of short-term changes of carbon isotope composition in the ocean. These isotope changes occurred due to the release of carbon from the ocean into the atmosphere that led to a temperature increase of 4-8 °C (7.2-14.4 °F) at the surface of the ocean. These hyperthermals led to increased perturbations in planktonic and benthic foraminifera, with a higher rate of sedimentation as a consequence of the warmer temperatures. Recent analysis of and research into these hyperthermals in the early Eocene has led to hypotheses that the hyperthermals are based on orbital parameters, in particular eccentricity and obliquity. The hyperthermals in the early Eocene, notably the Palaeocene-Eocene Thermal Maximum (PETM), the Eocene Thermal Maximum 2 (ETM2), and the Eocene Thermal Maximum 3 (ETM3), were analyzed and found that orbital control may have had a role in triggering the ETM2 and ETM3.
Greenhouse to icehouse climate
The Eocene is not only known for containing the warmest period during the Cenozoic, but it also marked the decline into an icehouse climate and the rapid expansion of the Antarctic ice sheet. The transition from a warming climate into a cooling climate began at ~49 million years ago. Isotopes of carbon and oxygen indicate a shift to a global cooling climate. The cause of the cooling has been attributed to a significant decrease of >2000 ppm in atmospheric carbon dioxide concentrations. One proposed cause of the reduction in carbon dioxide during the warming to cooling transition was the Azolla event. The increased warmth at the poles, the isolated Arctic basin during the early Eocene, and the significantly high amounts of carbon dioxide possibly led to azolla blooms across the Arctic Ocean. The isolation of the Arctic Ocean led to stagnant waters and as the azolla sank to the sea floor, they became part of the sediments and effectively sequestered the carbon. The ability for the azolla to sequester carbon is exceptional, and the enhanced burial of azolla could have had a significant effect on the world atmospheric carbon content and may have been the event to begin the transition into an ice house climate. Cooling after this event continued due to continual decrease in atmospheric carbon dioxide from organic productivity and weathering from mountain building.
Global cooling continued until there was a major reversal from cooling to warming indicated in the Southern Ocean at around 42-41 million years ago. Oxygen isotope analysis showed a large negative change in the proportion of heavier oxygen isotopes to lighter oxygen isotopes, which indicates an increase in global temperatures. This warming event is known as the Middle Eocene Climatic Optimum. The cause of the warming is considered to primarily be due to carbon dioxide increases, since carbon isotope signatures rule out major methane release during this short term warming. The increase in atmospheric carbon dioxide is considered to be due to increased seafloor spreading rates between Australia and Antarctica and increased amounts of volcanism in the region. Another possible atmospheric carbon dioxide increase could be during a sudden increase with metamorphic release during the Himalayan orogeny, however data on the exact timing of metamorphic release of atmospheric carbon dioxide is not well resolved in the data. Recent studies have mentioned, however, that the removal of the ocean between Asia and India could release significant amounts of carbon dioxide.This warming is short lived, as benthic oxygen isotope records indicate a return to cooling at ~40 million years ago.
Cooling continued throughout the rest of the Late Eocene into the Eocene-Oligocene transition. During the cooling period, benthic oxygen isotopes show the possibility of ice creation and ice increase during this later cooling. The end of the Eocene and beginning of the Oligocene is marked with the massive expansion of area of the Antarctic ice sheet that was a major step into the icehouse climate. Along with the decrease of atmospheric carbon dioxide reducing the global temperature, orbital factors in ice creation can be seen with 100,000 year and 400,000 year fluctuations in benthic oxygen isotope records. Another major contribution to the expansion of the ice sheet was the creation of the Antarctic circumpolar current. The creation of the Antarctic circumpolar current would isolate the cold water around the Antarctic, which would reduce heat transport to the Antarctic along with create ocean gyres that result in the upwelling of colder bottom waters. The issue with this hypothesis of the consideration of this being a factor for the Eocene-Oligocene transition is the timing of the creation of the circulation is uncertain. For Drake Passage, sediments indicate the opening occurred ~41 million years ago while tectonics indicate that this occurred ~32 million years ago.
Palaeogeography
During the Eocene, the continents continued to drift toward their present positions.
At the beginning of the period, Australia and Antarctica remained connected, and warm equatorial currents mixed with colder Antarctic waters, distributing the heat around the planet and keeping global temperatures high, but when Australia split from the southern continent around 45 Ma, the warm equatorial currents were routed away from Antarctica. An isolated cold water channel developed between the two continents. The Antarctic region cooled down, and the ocean surrounding Antarctica began to freeze, sending cold water and icefloes north, reinforcing the cooling.
The northern supercontinent of Laurasia began to break up, as Europe, Greenland and North America drifted apart.
In western North America, mountain building started in the Eocene, and huge lakes formed in the high flat basins among uplifts, resulting in the deposition of the Green River Formation lagerstätte.
At about 35 Ma, an asteroid impact on the eastern coast of North America formed the Chesapeake Bay impact crater.
In Europe, the Tethys Sea finally vanished, while the uplift of the Alps isolated its final remnant, the Mediterranean, and created another shallow sea with island archipelagos to the north. Though the North Atlantic was opening, a land connection appears to have remained between North America and Europe since the faunas of the two regions are very similar.
India continued its journey away from Africa and began its collision with Asia, folding the Himalayas into existence.
It is hypothesized that the Eocene hothouse world was caused by runaway global warming from released methane clathrates deep in the oceans. The clathrates were buried beneath mud that was disturbed as the oceans warmed. Methane (CH4) has ten to twenty times the greenhouse gas effect of carbon dioxide (CO2).
Flora
At the beginning of the Eocene, the high temperatures and warm oceans created a moist, balmy environment, with forests spreading throughout the Earth from pole to pole. Apart from the driest deserts, Earth must have been entirely covered in forests.
Polar forests were quite extensive. Fossils and even preserved remains of trees such as swamp cypress and dawn redwood from the Eocene have been found on Ellesmere Island in the Arctic. Even at that time, Ellesmere Island was only a few degrees in latitude further south than it is today. Fossils of subtropical and even tropical trees and plants from the Eocene have also been found in Greenland and Alaska. Tropical rainforests grew as far north as northern North America and Europe.
Palm trees were growing as far north as Alaska and northern Europe during the early Eocene, although they became less abundant as the climate cooled. Dawn redwoods were far more extensive as well.
Cooling began mid-period, and by the end of the Eocene continental interiors had begun to dry out, with forests thinning out considerably in some areas. The newly evolved grasses were still confined to river banks and lake shores, and had not yet expanded into plains and savannas.
The cooling also brought seasonal changes. Deciduous trees, better able to cope with large temperature changes, began to overtake evergreen tropical species. By the end of the period, deciduous forests covered large parts of the northern continents, including North America, Eurasia and the Arctic, and rainforests held on only in equatorial South America, Africa, India and Australia.
Antarctica, which began the Eocene fringed with a warm temperate to sub-tropical rainforest, became much colder as the period progressed; the heat-loving tropical flora was wiped out, and by the beginning of the Oligocene, the continent hosted deciduous forests and vast stretches of tundra.
The oldest known fossils of most of the modern mammal orders appear within a brief period during the early Eocene. At the beginning of the Eocene, several new mammal groups arrived in North America. These modern mammals, like artiodactyls, perissodactyls and primates, had features like long, thin legs, feet and hands capable of grasping, as well as differentiated teeth adapted for chewing. Dwarf forms reigned. All the members of the new mammal orders were small, under 10 kg; based on comparisons of tooth size, Eocene mammals were only 60% of the size of the primitive Palaeocene mammals that preceded them. They were also smaller than the mammals that followed them. It is assumed that the hot Eocene temperatures favored smaller animals that were better able to manage the heat.
Both groups of modern ungulates (hoofed animals) became prevalent because of a major radiation between Europe and North America, along with carnivorous ungulates like Mesonyx. Early forms of many other modern mammalian orders appeared, including bats, proboscidians (elephants), primates, rodents and marsupials. Older primitive forms of mammals declined in variety and importance. Important Eocene land fauna fossil remains have been found in western North America, Europe, Patagonia, Egypt and southeast Asia. Marine fauna are best known from South Asia and the southeast United States.
Reptile fossils from this time, such as fossils of pythons and turtles, are abundant. The remains of Titanoboa, a snake the length of a school bus, was discovered in South America along with other large reptilian megafauna. During the Eocene, plants and marine faunas became quite modern. Many modern bird orders first appeared in the Eocene.
Several rich fossil insect faunas are known from the Eocene, notably the Baltic amber found mainly along the south coast of the Baltic Sea, amber from the Paris Basin, France, the Fur Formation, Denmark and the Bembridge Marls from the Isle of Wight, England. Insects found in Eocene deposits are mostly assignable to modern genera, though frequently these genera do not occur in the area at present. For instance the bibionid genus Plecia is common in fossil faunas from presently temperate areas, but only lives in the tropics and subtropics today.
Oceans
The Eocene oceans were warm and teeming with fish and other sea life. The first carcharinid sharks evolved, as did early marine mammals, including Basilosaurus, an early species of whale that is thought to be descended from land animals that existed earlier in the Eocene, the hoofed predators called mesonychids, of which Mesonyx was a member. The first sirenians, relatives of the elephants, also evolved at this time.
Eocene–Oligocene extinction
The end of the Eocene was marked by the Eocene–Oligocene extinction event, also known as the Grande Coupure.
The above story is based on materials provided by Wikipedia
The Paleocene or Palaeocene, the “old recent”, is a geologic epoch that lasted from about 66 to 56 million years ago. It is the first epoch of the Palaeogene Period in the modern Cenozoic Era. As with many geologic periods, the strata that define the epoch’s beginning and end are well identified, but the exact ages remain uncertain.
The Paleocene Epoch brackets two major events in Earth’s history. It started with the mass extinction event at the end of the Cretaceous, known as the Cretaceous-Paleogene (K-Pg) boundary. This was a time marked by the demise of non-avian dinosaurs, giant marine reptiles and much other fauna and flora. The die-off of the dinosaurs left unfilled ecological niches worldwide. It ended with the Paleocene-Eocene Thermal Maximum. This was a geologically brief (~0.2 million year) interval characterized by extreme changes in climate and carbon cycling.
The name “Paleocene” comes from Greek and refers to the “old(er)” (παλαιός, palaios) “new” (καινός, kainos) fauna that arose during the epoch.
Boundaries and subdivisions
The K–Pg boundary that marks the separation between Cretaceous and Paleocene is visible in the geological record of much of the Earth by a discontinuity in the fossil fauna, with high iridium levels. There is also fossil evidence of abrupt changes in flora and fauna. There is some evidence that a substantial but very short-lived climatic change may have happened in the very early decades of the Paleocene. There are several theories about the cause of the K-Pg extinction event, with most evidence supporting the impact of a 10 km diameter asteroid forming the buried Chicxulub crater on the coast of Yucatan, Mexico.
The end of the Paleocene (~55.8 Ma) was also marked by a time of major change. one of the most significant periods of global change during the Cenozoic. The Paleocene-Eocene Thermal Maximum upset oceanic and atmospheric circulation and led to the extinction of numerous deep-sea benthic foraminifera and a major turnover in mammals on land.
The Paleocene is divided into three stages, the Danian, the Selandian and the Thanetian, as shown in the table above. Additionally, the Paleocene is divided into six Mammal Paleogene zones.
Climate
The early Paleocene was cooler and dryer than the preceding Cretaceous, though temperatures rose sharply during the Paleocene–Eocene Thermal Maximum. The climate became warm and humid worldwide towards the Eocene boundary, with subtropical vegetation growing in Greenland and Patagonia, crocodiles swimming off the coast of Greenland, and early primates evolving in tropical palm forests of northern Wyoming. The Earth’s poles were cool and temperate; North America, Europe, Australia and southern South America were warm and temperate; equatorial areas had tropical climates; and north and south of the equatorial areas, climates were hot and arid.
Paleogeography
In many ways, the Paleocene continued processes that had begun during the late Cretaceous Period. During the Paleocene, the continents continued to drift toward their present positions. Supercontinent Laurasia had not yet separated into three continents – Europe and Greenland were still connected, North America and Asia were still intermittently joined by a land bridge, while Greenland and North America were beginning to separate. The Laramide orogeny of the late Cretaceous continued to uplift the Rocky Mountains in the American west, which ended in the succeeding epoch.
South and North America remained separated by equatorial seas (they joined during the Neogene); the components of the former southern supercontinent Gondwanaland continued to split apart, with Africa, South America, Antarctica and Australia pulling away from each other. Africa was heading north towards Europe, slowly closing the Tethys Ocean, and India began its migration to Asia that would lead to a tectonic collision and the formation of the Himalayas.
The inland seas in North America (Western Interior Seaway) and Europe had receded by the beginning of the Paleocene, making way for new land-based flora and fauna.
Oceans
Warm seas circulated throughout the world, including the poles. The earliest Paleocene featured a low diversity and abundance of marine life, but this trend reversed later in the epoch. Tropical conditions gave rise to abundant marine life, including coral reefs. With the demise of marine reptiles at the end of the Cretaceous, sharks became the top predators. At the end of the Cretaceous, the ammonites and many species of foraminifera became extinct.
Marine fauna also came to resemble modern fauna, with only the marine mammals and the Carcharhinid sharks missing.
Flora
Terrestrial Paleocene strata immediately overlying the K–Pg boundary is in places marked by a “fern spike”: a bed especially rich in fern fossils. Ferns are often the first species to colonize areas damaged by forest fires; thus the fern spike may indicate post-Chicxulub crater devastation.
In general, the Paleocene is marked by the development of modern plant species. Cacti and palm trees appeared. Paleocene and later plant fossils are generally attributed to modern genera or to closely related taxa.
The warm temperatures worldwide gave rise to thick tropical, sub-tropical and deciduous forest cover around the globe (the first recognizably modern rain forests) with ice-free polar regions covered with coniferous and deciduous trees. With no large grazing dinosaurs to thin them, Paleocene forests were probably denser than those of the Cretaceous.
Flowering plants (angiosperms), first seen in the Cretaceous, continued to develop and proliferate, and along with them coevolved the insects that fed on these plants and pollinated them.
Fauna
Mammals
Mammals had first appeared in the Triassic, evolving from advanced cynodonts, and developed alongside the dinosaurs, exploiting ecological niches untouched by the larger and more famous Mesozoic animals: in the insect-rich forest underbrush and high up in the trees. These smaller mammals (as well as birds, reptiles, amphibians, and insects) survived the mass extinction at the end of the Cretaceous which wiped out the non-avian dinosaurs, and mammals diversified and spread throughout the world.
While early mammals were small nocturnal animals that mostly ate soft plant material and small animals such as insects, the demise of the non-avian dinosaurs and the beginning of the Paleocene saw mammals growing bigger and occupying a wider variety of ecological niches. Ten million years after the death of the non-avian dinosaurs, the world was filled with rodent-like mammals, medium sized mammals scavenging in forests, and large herbivorous and carnivorous mammals hunting other mammals, birds, and reptiles.
Fossil evidence from the Paleocene is scarce, and there is relatively little known about mammals of the time. Because of their small size (constant until late in the epoch) early mammal bones are not well preserved in the fossil record, and most of what we know comes from fossil teeth (a much tougher substance), and only a few skeletons.
The brain to body mass ratios of these archaic mammals were quite low.
Mammals of the Paleocene include:
Monotremes: The ornithorhynchid Monotrematum sudamericanum, in the family that includes the platypus, is the only monotreme known from the Paleocene.
Marsupials: modern kangaroos are marsupials, characterized by giving birth to embryonic babies, who crawl into the mother’s pouch and suckle until they are developed. The Bolivian Pucadelphys andinus is a Paleocene example.
Multituberculates: the only major branch of mammals to become extinct since the K–Pg boundary, this rodent-like grouping includes the Paleocene Ptilodus.
Placentals: this grouping of mammals became the most diverse and the most successful. Members include primates, plesiadapids, proboscids, and hoofed ungulates, including the condylarths and the carnivorous mesonychids.
Reptiles
Because of the climatic conditions of the Paleocene, reptiles were more widely distributed over the globe than at present. Among the sub-tropical reptiles found in North America during this epoch are champsosaurs (aquatic reptiles that resemble modern gharials), crocodilia, soft-shelled turtles, palaeophi snakes, varanid lizards, and Protochelydra zangerli (similar to modern snapping turtles).
Examples of champsosaurs of the Paleocene include Champsosaurus gigas, the largest champsosaur ever discovered. This creature was unusual among Paleocene reptiles in that C. gigas became larger than its known Mesozoic ancestors: C. gigas is more than twice the length of the largest Cretaceous specimens (3 meters versus 1.5 meters). Reptiles as a whole decreased in size after the K-Pg event. Champsosaurs declined towards the end of the Paleocene and became extinct during the Miocene.
Examples of Paleocene crocodylians are Borealosuchus (formerly Leidyosuchus) formidabilis, the apex predator and the largest animal of the Wannagan Creek fauna, and the alligatorid Wannaganosuchus.
Non-avian dinosaurs may have survived to some extent into the early Danian stage of the Paleocene Epoch circa 64.5 Mya. The controversial evidence for such is a hadrosaur leg bone found from Paleocene strata in New Mexico; but such stray late forms may be derived fossils.
Birds
Gastornis fossil skeleton
Birds began to re-diversify during the epoch, occupying new niches. Most modern bird types had appeared by mid-Cenozoic, including perching birds, cranes, hawks, pelicans, herons, owls, ducks, pigeons, loons, and woodpeckers.
Large flightless birds have been found in late Paleocene deposits, including the herbivorous Gastornis in Europe and carnivorous terror birds in South America, the latter of which survived until the Pleistocene.
In the late Paleocene, early owl types appeared, such as Ogygoptynx in the United States and Berruornis in France.
Note : The above story is based on materials provided by Wikipedia
The Paleogene is a geologic period and system that began 66 and ended 23.03 million years ago and comprises the first part of the Cenozoic Era. Lasting 43 million years, the Paleogene is most notable as being the time in which mammals evolved from relatively small, simple forms into a large group of diverse animals in the wake of the Cretaceous–Paleogene extinction event that ended the preceding Cretaceous Period.
This period consists of the Paleocene, Eocene, and Oligocene Epochs. The end of the Paleocene (55.5/54.8 Mya) was marked by one of the most significant periods of global change during the Cenozoic, the Paleocene-Eocene Thermal Maximum, which upset oceanic and atmospheric circulation and led to the extinction of numerous deep-sea benthic foraminifera and on land, a major turnover in mammals. The Paleogene follows the Cretaceous Period and is followed by the Miocene Epoch of the Neogene Period. The terms ‘Paleogene System’ (formal) and ‘lower Tertiary System’ (informal) are applied to the rocks deposited during the ‘Paleogene Period’. The somewhat confusing terminology seems to be due to attempts to deal with the comparatively fine subdivisions of time possible in the relatively recent geologic past, when more information is preserved. By dividing the Tertiary Period into two periods instead of directly into five epochs, the periods are more closely comparable to the duration of ‘periods’ in the Mesozoic and Paleozoic Eras.
Climate and geography
The global climate during the Paleogene departed from the hot and humid conditions of the late Mesozoic era and began a cooling and drying trend which, although having been periodically disrupted by warm periods such as the Paleocene–Eocene Thermal Maximum, persists today. The trend was partly caused by the formation of the Antarctic Circumpolar Current, which significantly cooled oceanic water temperatures.The continents during the Paleogene continued to drift closer to their current positions. India was in the process of colliding with Asia, subsequently forming the Himalayas. The Atlantic Ocean continued to widen by a few centimeters each year. Africa was moving north to meet with Europe and form the Mediterranean, while South America was moving closer to North America (they would later connect via the Isthmus of Panama). Inland seas retreated from North America early in the period. Australia had also separated from Antarctica and was drifting towards Southeast Asia.
Mammals began a rapid diversification during this period. After the Cretaceous–Paleogene extinction event, which saw the demise of the non-avian dinosaurs, they transformed from a few small and generalized forms and began to evolve into most of the modern varieties we see today. Some of these mammals would evolve into large forms that would dominate the land, while others would become capable of living in marine, specialized terrestrial, and airborne environments. Some mammals took to the oceans and became modern cetaceans, while others took to the trees and became primates, the group to which humans belong. Birds, which were already well established by the end of the Cretaceous, also experienced an adaptive radiation as they took over the skies left empty by the now extinct Pterosaurs. Most other branches of life remained relatively unchanged in comparison to birds and mammals during this period.
As the Earth began to cool, tropical plants were less numerous and were now restricted to equatorial regions. Deciduous plants became more common, which could survive through the seasonal climate the world was now experiencing. One of the most notable floral developments during this period was the evolution of the first grass species. This new plant type expanded and formed new ecological environments we know today as savannas and prairies. These grasslands also began to replace many forests because they could survive better in the drier climate typical in many regions of the world during this period.
Geology
The Paleogene is notable in the context of offshore oil drilling, and especially in Gulf of Mexico oil exploration, where it is usually referred to as the “Lower Tertiary”. These rock formations represent the current cutting edge of deep-water oil discovery.Lower Tertiary rock formations encountered in the Gulf of Mexico oil industry tend to be comparatively high temperature and high pressure reservoirs, often with high sand content (70%+) or under very thick salt sediment layers.[8]
Lower Tertiary explorations to date include (partial list):
Kaskida Oil Field
Tiber Oil Field
Jack 2
The above story is based on materials provided by Wikipedia
