Chemical Formula: Ca5(PO4)3F Locality: Common world wide. Name Origin: Named as the fluorine end-member and from the Greek apatao – “I am misleading.”
Fluorapatite, often with the alternate spelling of fluoroapatite, is a phosphate mineral with the formula Ca5(PO4)3F (calcium fluorophosphate). Fluorapatite is a hard crystalline solid. Although samples can have various color (green, brown, blue, violet, or colorless), the pure mineral is colorless as expected for a material lacking transition metals. It is an important constituent of tooth enamel. Fluorapatite crystallizes in a hexagonal crystal system. It is often combined as a solid solution with hydroxylapatite (Ca5(PO4)3OH or Ca10(PO4)6(OH)2) in biological matrices. Chlorapatite (Ca5(PO4)3Cl) is another related structure. Industrially, the mineral is an important source of both phosphoric and hydrofluoric acids.
Fluorapatite as a mineral is the most common phosphate mineral. It occurs widely as an accessory mineral in igneous rocks and in calcium rich metamorphic rocks. It commonly occurs as a detrital or diagenic mineral in sedimentary rocks and is an essential component of phosphorite ore deposits. It occurs as a residual mineral in lateritic soils.
Physical Properties
Cleavage: {0001} Indistinct Color: Blue, Brown, Colorless, Violet, Green. Density: 3.1 – 3.2, Average = 3.15 Diaphaneity: Transparent to Opaque Fracture: Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments. Hardness: 5 – Apatite Luminescence: Fluorescent and phosphorescent. Luster: Vitreous – Resinous Streak: white
Stanford assistant professor Kate Maher holds up two different soil types. The soil on the left is young, dark, and composed of more chemically reactive minerals. The sample on the right is older and made up of less reactive minerals such as clays. Credit: Matthew Rothe
Favorable conditions for life on Earth are enabled in part by the natural shuttling of carbon dioxide from the planet’s atmosphere to its rocky interior and back again. Now Stanford scientists have devised a pair of math equations that better describe how topography, rock compositions and the movement of water through a landscape affects this vital recycling process.
Scientists have long suspected that the so-called the geologic carbon cycle is responsible for Earth’s clement and life-friendly conditions because it helps regulate atmospheric concentrations of CO2, a greenhouse gas that acts to trap the sun’s heat. This cycle is also thought to have played an important role in slowly thawing the planet during those rare times in the past when temperatures dipped so low that the globe was plunged into a “snowball-Earth” scenario and glaciers blanketed the equator.
“Our equations suggest that different landscapes have different potentials for regulating the transfer of carbon dioxide,” said Kate Maher, assistant professor of Geological and Environmental Sciences who developed the equations along with her colleague, Environmental Earth System Science professor Page Chamberlain. The research, which was supported by the National Research Foundation, is described in the March 14 issue of the journal Science.
The geologic carbon cycle begins when volcanoes release carbon dioxide into the atmosphere. Some of the CO2 mixes with rainwater and falls back to Earth as carbonic acid. On land, the carbonic acid chemically erodes, or “weathers,” silicate rocks exposed at Earth’s surface to produce bicarbonate and release elements such as calcium and magnesium that eventually wash into the ocean. Over millions of years, these elements are transformed into rocks such as limestone. When plate tectonics push the carbonate-loaded seafloor down into Earth’s mantle, the carbon is released again as CO2, which is vented back into the atmosphere through volcanic eruptions, thereby completing the cycle.
The equations developed by Maher and Chamberlain address the weathering component of the geologic carbon cycle. The amount of weathering that occurs depends on several factors. One is the makeup of the soil: older soils that have already been weathered dissolve more slowly compared to soils made of fresh rock. “As you weather soil and sediment over time, they become less and less chemically reactive,” Maher said. “Physical erosion, which is often associated with mountainous regions, replenishes the soil with reactive minerals.”
Another consideration is the length of time that water spends flowing through the soil, a variable that scientists call the “fluid travel time.” The more time rainwater spends flowing through soils, the more weathering that occurs. The fluid travel time is in turn affected by the topography of the landscape-water tends to flow more slowly across a flat surface than down an incline.
In the real world, these different factors interact in complex ways. They might work together to speed up the weathering process, or they could oppose each other to slow the process down. For example, consider precipitation falling onto a mountain. Because of gravity, the corrosive water may flow more quickly through the mountain, thus reducing the fluid travel time. However, the soils in mountainous regions also tend to be younger and thus richer in elements such as calcium and magnesium, and as a result are more reactive and easily weathered. The competition between the flow of water and the reactivity of the soils limits how much weathering can occur. Maher and Chamberlain argue that these limits are important for maintaining CO2 levels within an acceptable range to maintain temperatures suitable for life.
The equations could improve scientists’ understanding of the geologic carbon cycle by integrating the study of the interactions between the geologic and hydrologic factors that affect rock weathering. Prior to this, scientists tended to study the influence of topography and water on chemical weathering separately. “Our work provides a quantitative framework that links together many qualitative observations from modern weathering environments, but also provides new hypotheses regarding how these processes may work together,” Maher said.
Maher and Chamberlain are currently using real-world observations of rivers from around the world to modify and improve their equations.
Note : The above story is based on materials provided by Stanford University.
This is a tropical glacier in Papua New Guinea. Credit: Paul Warren and Lonnie Thompson
Using a cutting-edge research technique, UCLA researchers have reconstructed the temperature history of a region that plays a major role in determining climate around the world.
The findings, published online Feb. 27 in the journal Nature Geoscience, will help inform scientists about the processes influencing global warming in the western tropical Pacific Ocean.
The study analyzes how much temperatures have increased in the region near Indonesia, and how ocean temperatures affect nearby tropical glaciers in Papua New Guinea and Borneo. Researchers also evaluated the accuracy of existing climate model predictions for that region. The findings illustrate that the region is very sensitive to climate change and that it has warmed considerably over the last 20,000 years, since the last ice age.
The team chose the specific area examined in the study because it is Earth’s warmest open ocean region and a primary source of heat and water vapor to the atmosphere. As a result, temperature changes there can influence climate not just regionally, but globally.
“The tropical Pacific ocean-atmosphere system has been called a sleeping dragon because of how it can influence climate elsewhere,” said lead author Aradhna Tripati, a UCLA assistant professor in the departments of Earth, planetary and space sciences, and atmospheric and oceanic sciences.
Tripati and her team used a technique known as clumped isotope thermometry, which examines the calcium carbonate shells of marine plankton for subtle differences in the amounts of carbon-13 and oxygen-18 they contain. The researchers analyzed extensive modern and geological datasets, conducted theoretical calculations and examined climate model output. The group discovered that temperatures have changed by about 8 to 10 degrees Fahrenheit (4 to 5 degrees Celsius) over that span — more than scientists had previously thought, and more than most models have estimated.
“Most global climate models underestimate the average temperature variations that the region has experienced,” Tripati said, adding that the other models’ simulations may be incomplete or the models are not sensitive enough.
The UCLA team’s conclusions about temperature changes in the region also imply that there have been major fluctuations in the volume of water vapor in the atmosphere there.
As part of the study, Tripati and her colleagues also investigated what sets the past and present height of glaciers in the tropics, and why they have been retreating. To accurately estimate the height of tropical glaciers and average temperatures at altitude in this region, they found that atmospheric mixing, through a process known as entrainment, needs to be factored in.
“We found that the large amount of ocean warming goes a long way to explaining why glaciers have retreated so much,” said Tripati, a faculty member in the College of Letters and Science and a member of UCLA’s Institute of the Environment and Sustainability. “Throughout the region, they have retreated by close to a kilometer since the last ice age, and are predicted to disappear in the next one to three decades. Previously understanding this large-scale glacial retreat has been a puzzle. Our results help resolve this problem.”
Among the implications of the study are that ocean temperatures in this area may be more sensitive to changes in greenhouse gas levels than previously thought and that scientists should be factoring entrainment into their models for predicting future climate change.
The group has already begun a follow-up study, looking at sediment from Indonesia’s Lake Towuti to develop data that can be used to further improve models of climate and water cycling for the region. Researchers will also look at other places in the tropics, the Western U.S. and China.
Note : The above story is based on materials provided by University of California – Los Angeles.
Chemical Formula: Ca2Fe2+Al2BOSi4O15(OH) Locality: Boug d’Oisans, France. Name Origin: From the Greek acine – “ax” in allusion to the acute shape of typical crystals and the Latin – ferrum – “iron” in reference to the Fe in the chemical formula.
Axinite is a brown to violet-brown, or reddish-brown bladed group of minerals composed of calcium aluminium boro-silicate, (Ca,Fe,Mn)3Al2BO3Si4O12OH. Axinite is pyroelectric and piezoelectric.
Relative size of Nanuqsaurus hoglundi. Silhouettes showing approximate sizes of representative theropods. A, Nanuqsaurus hoglundi, based on holotype, DMNH 21461. B, Tyrannosaurus rex, based on FMNH PR2081. C, Tyrannosaurus rex, based on AMNH 5027. D, Daspletosaurus torosus, based on FMNH PR308; E, Albertosaurus sarcophagus, based on TMP 81.10.1; F, Troodon formosus, lower latitude individual based on multiple sources and size estimates; G, Troodon sp., North Slope individual based on extrapolation from measurements of multiple dental specimens [47]. Scale bar equals 1 m. Credit: From: Anthony R. Fiorillo, Ronald S. Tykoski. A Diminutive New Tyrannosaur from the Top of the World. PLoS ONE, 2014; 9 (3): e91287 DOI: 10.1371/journal.pone.0091287A 70 million year old fossil found in the Late Cretaceous sediments of Alaska reveals a new small tyrannosaur, according to a paper published in the open-access journal PLOS ONE on March 12, 2014 by co-authors Anthony Fiorillo and Ronald S. Tykoski from Perot Museum of Nature and Science, Texas, and colleagues.Tyrannosaurs, the lineage of carnivorous theropod (“beast feet”) dinosaurs that include T. rex, have captivated our attention, but the majority of our knowledge about this group comes from fossils from low- to mid-latitudes of North America and Asia. In this study, scientists analyzed the partial skull roof, maxilla, and jaw, recovered from Prince Creek Formation in Northern Alaska, of a dinosaur originally believed to belong to a different species, and then compared the fossils to known tyrannosaurine species.
According to the results of the authors’ analysis, the cranial bones represent Nanuqsaurus hoglundi, a new tyrannosaurine species closely related to two other tyrannosaurides, Tarbosaurus and Tyrannosaurus. This new dinosaur is estimated to be relatively small, with an adult skull length estimated at 25 inches, compared to 60 inches for T. rex. The new species likely inhabited a seasonally extreme, high-latitude continental environment on the northernmost edge of Cretaceous North America.
The authors suggest that the smaller body size of N. hoglundi compared to most tyrannosaurids from lower latitudes may reflect an adaptation to variability in resources in the arctic seasons. Further diversification may stem from the dinosaurs’ partial isolation in the north by land barriers, such as the east-west running Brooks Range. Although the preserved elements of N. hoglundi are fragments, the authors point to morphological data to provide support for its place among derived tyrannosaurines. This discovery may provide new insights into the adaptability and evolution of tyrannosaurs in a different environment, the Arctic.
“The ‘pygmy tyrannosaur’ alone is really cool because it tells us something about what the environment was like in the ancient Arctic,” said Fiorillo. “But what makes this discovery even more exciting is that Nanuqsaurus hoglundi also tells us about the biological richness of the ancient polar world during a time when the Earth was very warm compared to today.”
Note : The above story is based on materials provided by PLOS.
Projection of Earth warming by 2099: A new NASA study suggests that projections of Earth’s future warming should be more in line with previous estimates that indicated a higher sensitivity to increasing greenhouse gas emissions. Credit: NASA SVS/NASA Center for Climate Simulation
A Projection of Earth warming by 2099: A new NASA study suggests that projections of Earth’s future warming should be more in line with previous estimates that indicated a higher sensitivity to increasing greenhouse gas emissions.
new NASA study shows Earth’s climate likely will continue to warm during this century on track with previous estimates, despite the recent slowdown in the rate of global warming.
This research hinges on a new and more detailed calculation of the sensitivity of Earth’s climate to the factors that cause it to change, such as greenhouse gas emissions. Drew Shindell, a climatologist at NASA’s Goddard Institute for Space Studies in New York, found Earth is likely to experience roughly 20 percent more warming than estimates that were largely based on surface temperature observations during the past 150 years.
Shindell’s paper on this research was published March 9 in the journal Nature Climate Change.
Global temperatures have increased at a rate of 0.22 Fahrenheit (0.12 Celsius) per decade since 1951. But since 1998, the rate of warming has been only 0.09 F (0.05 C) per decade — even as atmospheric carbon dioxide continues to rise at a rate similar to previous decades. Carbon dioxide is the most significant greenhouse gas generated by humans.
Some recent research, aimed at fine-tuning long-term warming projections by taking this slowdown into account, suggested Earth may be less sensitive to greenhouse gas increases than previously thought. The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), which was issued in 2013 and was the consensus report on the state of climate change science, also reduced the lower range of Earth’s potential for global warming.
To put a number to climate change, researchers calculate what is called Earth’s “transient climate response.” This calculation determines how much global temperatures will change as atmospheric carbon dioxide continues to increase — at about 1 percent per year — until the total amount of atmospheric carbon dioxide has doubled. The estimates for transient climate response range from near 2.52 F (1.4 C) offered by recent research, to the IPCC’s estimate of 1.8 F (1.0 C). Shindell’s study estimates a transient climate response of 3.06 F (1.7 C), and determined it is unlikely values will be below 2.34 F (1.3 C).
Shindell’s paper further focuses on improving our understanding of how airborne particles, called aerosols, drive climate change in the Northern Hemisphere. Aerosols are produced by both natural sources — such as volcanoes, wildfire and sea spray — and sources such as manufacturing activities, automobiles and energy production. Depending on their make-up, some aerosols cause warming, while others create a cooling effect. In order to understand the role played by carbon dioxide emissions in global warming, it is necessary to account for the effects of atmospheric aerosols.
While multiple studies have shown the Northern Hemisphere plays a stronger role than the Southern Hemisphere in transient climate change, this had not been included in calculations of the effect of atmospheric aerosols on climate sensitivity. Prior to Shindell’s work, such calculations had assumed aerosol impacts were uniform around the globe.
This difference means previous studies have underestimated the cooling effect of aerosols. When corrected, the range of likely warming based on surface temperature observations is in line with earlier estimates, despite the recent slowdown.
One reason for the disproportionate influence of the Northern Hemisphere, particularly as it pertains to the impact of aerosols, is that most human-made aerosols are released from the more industrialized regions north of the equator. Also, the vast majority of Earth’s landmasses are in the Northern Hemisphere. This furthers the effect of the Northern Hemisphere because land, snow and ice adjust to atmospheric changes more quickly than the oceans of the world.
“Working on the IPCC, there was a lot of discussion of climate sensitivity since it’s so important for our future,” said Shindell, who was lead author of the IPCC Fifth Assessment Report’s chapter on Anthropogenic and Natural Radiative Forcing. “The conclusion was that the lower end of the expected warming range was smaller than we thought before. That was a big discussion. Yet, I kept thinking, we know the Northern Hemisphere has a disproportionate effect, and some pollutants are unevenly distributed. But we don’t take that into account. I wanted to quantify how much the location mattered.”
Shindell’s climate sensitivity calculation suggests countries around the world need to reduce greenhouse gas emissions at the higher end of proposed emissions reduction ranges to avoid the most damaging consequences of climate change. “I wish it weren’t so,” said Shindell, “but forewarned is forearmed.”
The above story is based on materials provided by NASA/Goddard Space Flight Center.
The first terrestrial discovery of ringwoodite by University of Alberta scientist Graham Pearson confirms the presence of massive amounts of water 400 to 700 km beneath the Earth’s surface. Credit: University of Alberta
A University of Alberta diamond scientist has found the first terrestrial sample of a water-rich gem that yields new evidence about the existence of large volumes of water deep beneath the Earth.
An international team of scientists led by Graham Pearson, Canada Excellence Research Chair in Arctic Resources at the U of A, has discovered the first-ever sample of a mineral called ringwoodite. Analysis of the mineral shows it contains a significant amount of water—1.5 per cent of its weight—a finding that confirms scientific theories about vast volumes of water trapped 410 to 660 kilometres beneath the Earth, between the upper and lower mantle.
/div> “This sample really provides extremely strong confirmation that there are local wet spots deep in the Earth in this area,” said Pearson, a professor in the Faculty of Science, whose findings were published March 13 in Nature. “That particular zone in the Earth, the transition zone, might have as much water as all the world’s oceans put together.”
Diamond sample JUc29, from Juina, Brazil, containing the hydrous ringwoodite inclusion reported by Pearson et al., Nature 2014. Credit: Richard Siemens, University of Alberta
Ringwoodite is a form of the mineral peridot, believed to exist in large quantities under high pressures in the transition zone. Ringwoodite has been found in meteorites but, until now, no terrestrial sample has ever been unearthed because scientists haven’t been able to conduct fieldwork at extreme depths.
Pearson’s sample was found in 2008 in the Juina area of Mato Grosso, Brazil, where artisan miners unearthed the host diamond from shallow river gravels. The diamond had been brought to the Earth’s surface by a volcanic rock known as kimberlite—the most deeply derived of all volcanic rocks.
The discovery that almost wasn’t
Pearson said the discovery was almost accidental in that his team had been looking for another mineral when they purchased a three-millimetre-wide, dirty-looking, commercially worthless brown diamond. The ringwoodite itself is invisible to the naked eye, buried beneath the surface, so it was fortunate that it was found by Pearson’s graduate student, John McNeill, in 2009.
“It’s so small, this inclusion, it’s extremely difficult to find, never mind work on,” Pearson said, “so it was a bit of a piece of luck, this discovery, as are many scientific discoveries.”
The sample underwent years of analysis using Raman and infrared spectroscopy and X-ray diffraction before it was officially confirmed as ringwoodite. The critical water measurements were performed at Pearson’s Arctic Resources Geochemistry Laboratory at the U of A. The laboratory forms part of the world-renowned Canadian Centre for Isotopic Microanalysis, also home to the world’s largest academic diamond research group.
The study is a great example of a modern international collaboration with some of the top leaders from various fields, including the Geoscience Institute at Goethe University, University of Padova, Durham University, University of Vienna, Trigon GeoServices and Ghent University.
For Pearson, one of the world’s leading authorities in the study of deep Earth diamond host rocks, the discovery ranks among the most significant of his career, confirming about 50 years of theoretical and experimental work by geophysicists, seismologists and other scientists trying to understand the makeup of the Earth’s interior.
Scientists have been deeply divided about the composition of the transition zone and whether it is full of water or desert-dry. Knowing water exists beneath the crust has implications for the study of volcanism and plate tectonics, affecting how rock melts, cools and shifts below the crust.
“One of the reasons the Earth is such a dynamic planet is the presence of some water in its interior,” Pearson said. “Water changes everything about the way a planet works.”
The above story is based on materials provided by University of Alberta.
Chemical Formula: FeWO4 Locality: Aquiles, Sierra Almagrera, Spain. Name Origin: Named after Moritz Rudolph Ferber (1805-1875) of Gera, Germany.Ferberite is the iron endmember of the manganese – iron wolframite solid solution series. The manganese endmember is hübnerite. Ferberite is a black monoclinic mineral composed of iron(II) tungstate, FeWO4.Ferberite and hübnerite often contain both divalent cations of iron and manganese, with wolframite as the intermediate species for which the solid solution series is named.
Ferberite occurs as granular masses and as slender prismatic crystals. It has a Mohs hardness of 4.5 and a specific gravity of 7.4 to 7.5. Ferberite typically occurs in pegmatites, granitic greisens, and high temperature hydrothermal deposits. It is a minor ore of tungsten.
Ferberite was discovered in 1863 in Sierra Almagrera, Spain, and named after the German mineralogist Moritz Rudolph Ferber (1805–1875).
Physical Properties
Cleavage: {010} Perfect, {100} Parting, {102} Parting Color: Black. Density: 7.5 – 7.4, Average = 7.45 Diaphaneity: Nearly opaque Fracture: Brittle – Uneven – Very brittle fracture producing uneven fragments. Hardness: 4.5 – Between Fluorite and Apatite Luster: Sub Metallic Streak: brownish black
Kayakers on Lake Superior in the Apostle Islands National Lakeshore, paddling along rocks deposited late in the evolution of the Midcontinent Rift. Credit: Seth Stein
Geologists from Northwestern University, the University of Illinois at Chicago, the University of Oklahoma and Purdue University have a new explanation for the Midwest’s biggest geologic mystery: What caused the giant 2,000-mile-long rift that starts in Lake Superior and runs south to Oklahoma and Alabama?
Using new data from the North American Midcontinent Rift and observations of rifting occurring today between Africa and Arabia, the scientists propose that the Midcontinent Rift formed when rocks now in South America rifted away from North America, forming a new ocean. As a result, rocks from the two sides match like pieces of a jigsaw puzzle.
The study was published March 5 in the journal Geophysical Research Letters.
A little more than a billion years ago, North America started to split, and 350,000 cubic miles of volcanic rock poured out. These rocks formed the valley that Lake Superior filled, and thick rock layers are exposed in the rift’s northern reaches but are underground elsewhere. The rocks of the Midcontinent Rift can be traced for thousands of miles underground because they are dense and highly magnetized.
“Although the rift made the Midwest’s best geology and scenery, we’ve never had a good explanation for what caused it,” said the study’s lead author, Carol A. Stein, professor of Earth and Environmental Sciences at the University of Illinois at Chicago. “The best we could do was to say that a plume of hot stuff came up under North America, for some unknown reason, and then stopped. That was never a satisfying explanation.”
To solve the puzzle, the geologists looked at a similar geologic feature forming today, the East African Rift that is splitting up Africa, causing the huge rift valley and volcanoes like Mount Kilimanjaro.
“The rift system is splitting Africa and rifting Arabia away from it, forming new ocean basins in the Red Sea and Gulf of Aden,” explained Seth Stein, the William Deering Professor of Geological Sciences at Northwestern’s Weinberg College of Arts and Sciences. “We see the same thing at other times in the past—rifts form and break continents apart. Once rifting succeeds in forming a new ocean, the leftover piece of rift shuts down. This seems to be how the Midcontinent Rift formed.”
Detailed mapping of the underground Midcontinent Rift using gravity data from G. Randy Keller, professor of geophysics at the University of Oklahoma in Norman and director of the Oklahoma Geological Survey, shows that the rift extends much farther than had been previously thought.
“It’s not just in the middle of the continent—it goes all the way to what was then the edge of the continent,” Keller said.
After putting the lines of evidence together, Carol Stein said, “The whole story now makes sense. We used to think of the Midcontinent Rift as this weird feature that started and died in the middle of a continent. Now we realize it formed as part of the rifting that split rocks now in South America off from North America. So instead of being a mysterious special case, we realize it formed in a way that’s familiar to geologists and what we see today and in the past. That’s gratifying because scientists hate to invoke special cases.”
The study is part of the National Science Foundation’s EarthScope program, in which geologists from across the U.S. are studying how North America formed.
Seth Stein, one of EarthScope’s organizers, said, “This is the kind of big advance we were hoping for. You can never predict breakthroughs, but when good people work together they often happen. It’s great that we got one for the Midwest because sometimes people think that exciting geology only happens in places like California. We hope results like this will encourage young Midwesterners to study geology and make even further advances.”
Note : The above story is based on materials provided by Northwestern University
This graphic shows the global carbon budget with black arrows and values reflecting the natural carbon cycle and red the anthropogenic perturbation. Credit: 2007 IPCC report
Nothing dies of old age in the ocean. Everything gets eaten and all that remains of anything is waste. But that waste is pure gold to oceanographer David Siegel, director of the Earth Research Institute at UC Santa Barbara.
In a study of the ocean’s role in the global carbon cycle, Siegel and his colleagues used those nuggets to their advantage. They incorporated the lifecycle of phytoplankton and zooplankton—small, often microscopic animals at the bottom of the food chain —into a novel mechanistic model for assessing the global ocean carbon export. Their findings appear online in the journal Global Biogeochemical Cycles.
The researchers used satellite observations including determinations of net primary production (NPP)—the net production of organic matter from aqueous carbon dioxide (CO2) by phytoplankton—to drive their food-web-based model. The scientists focused on the ocean’s biological pump, which exports organic carbon from the euphotic zone—the well-lit, upper ocean—through sinking particulate matter, largely from zooplankton feces and aggregates of algae. Once these leave the euphotic zone, sinking into the ocean depths, the carbon can be sequestered for a season or for centuries.
“What we’ve done here is create the first step toward monitoring the strength and efficiency of the biological pump using satellite observations,” said Siegel, who is also a professor of marine science in UCSB’s Department of Geography. “The approach is unique in that previous ways have been empirical without considering the dynamics of the ocean food web.” The space/time patterns created by those empirical approaches are inconsistent with how oceanographers think the oceans should work, he noted.
Carbon is present in the atmosphere and is stored in soils, oceans and the Earth’s crust. Any movement of carbon between—or in the case of the ocean, within—these reservoirs is called a flux. According to the researchers, oceans are a central component in the global carbon cycle through their storage, transport and transformations of carbon constituents.
Shown are the links among the ocean’s biological pump and pelagic food web. Light blue waters are the euphotic zone, while the darker blue waters represent the twilight zone. Credit: US Joint Global Ocean Flux Study
“Quantifying this carbon flux is critical for predicting the atmosphere’s response to changing climates,” Siegel said. “By analyzing the scattering signals that we got from satellite measurements of the ocean’s color, we were able to develop techniques to calculate how much of the biomass occurs in very large or very small particles.”
Their results predict a mean global carbon export flux of 6 petagrams (Pg) per year. Also known as a gigaton, a petagram is equal to one quadrillion (1015) grams. This is a huge amount, roughly equivalent to the annual global emissions of fossil fuel. At present, fossil fuel combustion represents a flux to the atmosphere of approximately 9 Pg per year.
Global mean determinations of the efficiency of the biological pump from (left) the present food-web model and (right) an empirical method that models export efficiency as a function of the sea surface temperature (SST). Credit: UCSB
“It matters how big and small the plankton are, and it matters what the energy flows are in the food web,” Siegel said. “This is so simple. It’s really who eats whom but also having an idea of the biomasses and productivity of each. So we worked out these advanced ways of determining NPP, phytoplankton biomass and the size structure to formulate mass budgets, all derived from satellite data.”
The researchers are taking their model one step further by planning a major field program designed to better understand the states in which the biological pump operates. “Understanding the biological pump is critical,” Siegel concluded. “We need to understand where carbon goes, how much of it goes into the organic matter, how that affects the air-sea exchanges of CO2 and what happens to fossil fuel we have emitted from our tailpipes.”
Note : The above story is based on materials provided by University of California – Santa Barbara
This method could be used in place of having to drill a ‘monitoring well’ as done in conventional cross-well surveys. Credit: Eric Hodel
A hydro-geologist has found an inexpensive, high-quality three-dimensional imaging method for aquifers and other below-ground features.
Conventional cross-well surveys require a monitoring bore containing sensors, and another source well in which a seismic shock is produced.
Now, PhD student Majed Al Malki has eliminated the need for a dedicated monitoring well, if two bores are already available.He developed a method whereby he placed sensors in two existing vertical wells and created a shock wave at a fixed point on the surface.
He then measured and interpreted the differences between signals received at varying depths in the two wells to produce an image of the geology in between.
“When compared to conventional walkaway vertical seismic profiling, the only additional effort required to complete dual-well walkaway vertical seismic profiling is the deployment of seismic sensors in the second well,” Dr Al Malki says.
He conducted the experiments at the Water Corporation’s Mirrabooka aquifer storage and recovery site during his PhD studies, under the supervision of Curtin University Associate Professor Brett Harris.
“[This project] was looking at banking excess water in the shallow aquifers into deeper aquifers that are slightly depleted,” Prof Harris says.
“The main thing was to look for ways of characterising the rock around those formations.”
He says they used a 1000kg piece of concrete, dropped from a Bobcat, as a weight-drop source of seismic energy.
“[The] surface source bangs the ground on, in our case, about 150 locations and then we use the energy as it propagates through the earth between the two wells.
“The path of the seismic energy goes from one well to the other well but all at different angles from the different source positions on the surface.”
He says this allows them to reconstruct sub-surface source positions in the well nearest to the seismic energy source.
“It looks like there was a source there without you actually having to put one there,” he says.
“That information can be used to actually reconstruct what a source would look like if it were located underground.”
He says the beauty of this method is that there is no need to place a seismic shock source inside a purpose-drilled hole.
“It’s really a non-invasive method of understanding what the distribution of the key interfaces are,” Prof Harris says.
He says the technique could be applied to assess underground environments for petroleum, geothermal and groundwater reserves and carbon storage sites.
Note : The above story is based on materials provided by Science Network WA
A file picture taken on March 13, 2009 shows the skeleton of a Cryolophosaurus Ellioti, diplayed at the exhibition “Dinosaurs of Gondwana” at the National Science Museum in Tokyo
The space rock that smashed into Earth 65 million years ago, famously wiping out the dinosaurs, unleashed acid rain that turned the ocean surface into a witches’ brew, researchers said Sunday.
Delving into the riddle of Earth’s last mass extinction, Japanese scientists said the impact instantly vaporised sulphur-rich rock, creating a vast cloud of sulphur trioxide (SO3) gas.
This mixed with water vapour to create sulphuric acid rain, which would have fallen to the planet’s surface within days, acidifying the surface levels of the ocean and killing life therein.
Those species that were able to survive beneath this lethal layer eventually inherited the seas, according to the study which did not delve into the effects on land animals.
“Concentrated sulphuric acid rains and intense ocean acidification by SO3-rich impact vapours resulted in severe damage to the global ecosystem and were probably responsible for the extinction of many species,” the study said.
The great smashup is known as the Cretaceous-Tertiary extinction.
It occurred when an object, believed to be an asteroid some 10 kilometres (six miles) wide, whacked into the Yucatan peninsula in modern-day Mexico.
It left a crater 180 kilometres (110 miles) wide, ignited a firestorm and kicked up a storm of dust that was driven around the world on high winds, according to the mainstream scenario.
Between 60 and 80 percent of species on Earth were wiped out, according to fossil surveys.
Large species suffered especially: dinosaurs which had roamed the land for some 165 million years, were replaced as the terrestrial kings by mammals.
Extinction riddle
Much speculation has been devoted to precisely how the mass die-out happened.
A common theory is that a “nuclear winter” occurred—the dust pall prevented sunlight reaching the surface, causing vegetation to shrivel and die, and dooming the species that depended on them.
Another, fiercely debated, idea adds acid rain to the mix.
Critics say the collision was far likelier to have released sulphur dioxide (SO2) than SO3, the culprit chemical in acid rain. And, they argue, it would have lingered in the stratosphere rather than fallen back to Earth.
Seeking answers, a team led by Sohsuke Ohno of the Planetary Exploration Research Centre in Chiba set up a special lab rig to replicate—on a tiny scale—what happened that fateful day.
They used a laser beam to vaporise a strand of plastic, which released a high-speed blast of plasma and caused a tiny piece of foil, made of the heavy metal tantalum, to smash into a sample of rock.
The heavy foil fragment replicated on a miniscule scale the mass of the asteroid, while the rock was of a similar makeup as the surface where the asteroid struck.
The team caused collisions ranging from 13 to 25 km per second (47,000-90,000 km or 29,000-55,000 miles per hour), and analysed the gas that was released.
The research, reported in the journal Nature Geoscience, showed that SO3 was by far the dominant molecule, not SO2.
The team also carried out a computer simulation of larger silicate particles that would have been ejected by the impact, and found they too played a part.
The articles rapidly bound with the poisonous vapour to become sulphur acid “aerosols” that fell to the surface.
Heavily acidic waters would explain the overwhelming extinction among surface species of plankton called foraminifera.
Foraminifera are single-celled creatures protected by a calcium carbonate shell, which dissolves in acidic water.
The “acid rain” scenario also helps explain other extinction riddles, including why there was a surge in the number of ferns species after the impact. Ferns love acidic, water-logged conditions such as those described in the study.
This image shows a man standing in volanic steam in Antartica. Credit: Peter Convey, British Antartic Survey
An international team of researchers has found evidence that the steam and heat from volcanoes and heated rocks allowed many species of plants and animals to survive past ice ages, helping scientists understand how species respond to climate change. The research could solve a long-running mystery about how some species survived and continued to evolve through past ice ages in parts of the planet covered by glaciers. The team, led by Dr Ceridwen Fraser from the Australian National University and Dr Aleks Terauds from the Australian Antarctic Division, studied tens of thousands of records of Antarctic species, collected over decades by hundreds of researchers, and found there are more species close to volcanoes, and fewer further away.
“Volcanic steam can melt large ice caves under the glaciers, and it can be tens of degrees warmer in there than outside. Caves and warm steam fields would have been great places for species to hang out during ice ages,” Dr Fraser said. “We can learn a lot from looking at the impacts of past climate change as we try to deal with the accelerated change that humans are now causing.” While the study was based on Antarctica, the findings help scientists understand how species survived past ice ages in other icy regions, including in periods when it is thought there was little or no ice-free land on the planet. Antarctica has at least 16 volcanoes which have been active since the last ice age 20,000 years ago. The study examined diversity patterns of mosses, lichens and bugs which are still common in Antarctica today. Professor Peter Convey from the British Antarctic Survey said around 60 per cent of Antarctic invertebrate species are found nowhere else in the world. “They have clearly not arrived on the continent recently, but must have been there for millions of years. How they survived past ice ages – the most recent of which ended less than 20,000 years ago – has long puzzled scientists,” Professor Convey said. Dr Terauds of the Australian Antarctic Division ran the analyses, and says the patterns are striking. “The closer you get to volcanoes, the more species you find. This pattern supports our hypothesis that species have been expanding their ranges and gradually moving out from volcanic areas since the last ice age,” Dr Terauds said. Professor Steven Chown, from Monash University, says the research findings could help guide conservation efforts in Antarctica. “Knowing where the ‘hotspots’ of diversity are will help us to protect them as human-induced environmental changes continue to affect Antarctica,” Professor Chown said. Note : The above story is based on materials provided by Australian National University
Chemical Formula: (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6 Locality: Jolster, Sondfjord, Norway. Name Origin: From the Greek for “friendly to strangers, hospitable,” in allusion to the rare elements that it contains.
Euxenite, which is sometimes named euxenite-(Y) (the Y is for the yttrium), is a mineral that is sometimes called a “trash can mineral”. Because it will accommodate a wide variety of elements in its crystal structure, generally the elements that other minerals do not seem to want, ie the “trash”. For euxenite, these elements are in a group called the rare earths and are sometimes quite valuable, making euxenite a potentially profitable ore. Euxenite’s name is from a Greek phrase meaning “hospitable”, another reference to its . . . accommodating nature.
Euxenite is in a series with the mineral polycrase, another “trash can mineral”. Polycrase is simply richer in titanium as opposed to the niobium rich euxenite. The other elements can be found in both minerals and the structure is basically the same.
Physical Properties
Cleavage: None Color: Brownish black, Brown, Yellow, Olive green. Density: 4.7 – 5, Average = 4.84 Diaphaneity: Translucent to opaque Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals. Hardness: 6.5 – Pyrite Luminescence: Non-fluorescent. Luster: Greasy (Oily) Streak: reddish brown
Chemical Formula: Na15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2 Locality: Julianehaab district of Greenland. Name Origin: From the Greek eu – “well” and dialytos – “decomposable.”
Eudialyte, whose name derives from the Greek phrase Εὖ διάλυτος eu dialytos, meaning “well decomposable”, is a somewhat rare, nine member ring cyclosilicate mineral, which forms in alkaline igneous rocks, such as nepheline syenites. Its name alludes to its ready solubility in acid.
Eudialyte was first described in 1819 for an occurrence in nepheline syenite of the Ilimaussaq intrusive complex of southwest Greenland.
Alternative names
Alternative names of eudialyte include: almandine spar, eudalite, Saami blood. Eucolite is the name of an optically negative variety, more accurately the group member: ferrokentbrooksite.
Physical Properties
Cleavage: {0001} Imperfect Color: Pinkish red, Red, Yellow, Yellowish brown, Violet. Density: 2.8 – 3, Average = 2.9 Diaphaneity: Transparent to Translucent Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern. Hardness: 5-5.5 – Apatite-Knife Blade Luminescence: Non-fluorescent. Luster: Vitreous (Glassy) Streak: white
Pridoli Series, uppermost of four main divisions of the Silurian System, representing those rocks deposited worldwide during the Pridoli Epoch (423 million to 419.2 million years ago). The series name is derived from the Pridoli area of the Daleje Valley on the outskirts of Prague in the Czech Republic, where about 20 to 50 metres (about 65 to 165 feet) of platy limestone strata rich in cephalopods and bivalves are well-developed.
By international agreement, the base of the Pridoli Series is defined by the first occurrence of the graptolite species Monograptus parultimus in rock exposures at the entrance to the Pozary Quarries, which lie about 1.5 km (about 1 mile) east of Reporyje, outside of southwestern Prague. The M. parultimus biozone, in short, constitutes the global stratotype section and point (GSSP) for the base of the series. In addition, two species of chitinozoans (a type of marine plankton), Urnochitina urna and Fungochitina kosovensis, first occur at or just above the base of the series. The earliest known simple vascular land plants, of the genus Cooksonia, typically occur in the lower portions of the Pridoli Series in many parts of the world. The Pridoli Series is overlain by the Lochkovian Stage, the first stage of the Devonian System. The base of the Lochkovian and the base of the Devonian System automatically define the top of the Pridoli and thus the top of the Silurian System. The Pridoli Series has not been divided into stages and is underlain by the Ludlow Series.
The Ludlow Group are rocks deposited during the Ludlow period of the Silurian in Great Britain. This group contains the following formations in descending order:
Cilestones, Downton Castle sandstones (90 ft./27.7 m),
Ledbury shales 270 ft./83 m),
Upper Ludlow rocks (140 ft./43 m),
Aymestry limestone (up to 40 ft./12.3 m),
Lower Ludlow rocks (350 to 780 ft./108 m-240 m).
The Ludlow group is essentially shaly in character, except towards the top, where the beds become more sandy and pass gradually into the Old Red Sandstone. The Aymestry limestone, which is irregular in thickness, is sometimes absent, and where the underlying Wenlock limestones are absent the shales of the Ludlow group graduate, downwards into the Wenlock shales. The group is typically developed between Ludlow and Aymestrey, and it occurs also in the detached Silurian areas between Dudley and the mouth of the Severn.
The Lower Ludlow rocks are mainly grey, greenish and brown mudstones and sandy and calcareous shales. They contain an abundance of fossils. The series has been zoned by means of the Graptolites by E. M. R. Wood; the following in ascending order, are the zonal forms:
Monograptus vulgaris,
M. Nilssoni,
M. scanicus,
M. tumescens and
M. leintwardinensis.
Cyathaspis ludensis, the earliest British vertebrate fossil, was found in these rocks at Leintwardine in Herefordshire, a noted fossil locality. Trilobites are numerous (Phacops caudatus, Lichas anglicus, Homolonotus delphinocephalus, Calymene Blumenbachii); brachiopods (Leptaena rhomboidalis, Rhynchonella Wilsoni, Atrypa reticularis}, pelecypods (Cardiola interrupts, Ctenodonta sulcata) and gasteropods and cephalopods (many species of Orthoceras and also Gomphoceras, Trochoceras) are well represented. Other fossils are Ceratiocaris , Pterygotus, Protaster, Palaeocoma and Palaeodiscus.
The Upper Ludlow rocks are mainly soft mudstones and shales with some harder sandy beds capable of being worked as building-stones. These sandy beds are often found covered with ripple-marks and annelid tracks; one of the uppermost sandy layers is known as the ” Fucoid bed ” from the abundance of the seaweed-like impressions it bears. At the top of this sub-group, near Ludlow, a brown layer occurs, from a quarter of an inch to 4 in. (63 mm to 100 mm) in thickness, full of the fragmentary remains of fish associated with those of Pterygotus and mollusca. This layer, known as the ” Ludlow Bone bed,” has been traced over a very large area (see Bone Bed). The common fossils include plants (Actinophyllum, Chondrites), ostracods, phyllocarids, eurypterids, trilobites (less common than in the older groups), numerous brachiopods (Lingula minima, Chonetes striatella), gasteropods, pelecypods and cephalopods (Orthoceras bullatum). Fish include Cephalaspis, Cyathaspis, Auchenaspis. The Tilestones, Downton Castle Sandstone and Ledbury shales are occasionally grouped together under the term Downtonian. They are in reality passage beds between the Silurian and Old Red Sandstone, and were originally placed in the latter system by Sir R. I. Murchison. They are mostly grey, yellow or red micaceous, shaly sandstones. Lingula cornea, Platyschisma helicites and numerous phyllocarids and ostracods occur among the fossils.
In Denbighshire and Merionethshire the upper portion of the Denbighshire Grits belongs to this horizon: viz. those from below upwards, the Nantglyn Flags, the Upper Grit beds, the Monograptus leintwardinensis beds and the Dinas Bran beds. In the Silurian area of the Lake district the Coldwell beds, forming the upper part of the Coniston Flags, are the equivalents of the Lower Ludlow; they are succeeded by the Coniston Grits (4,000 ft./1,230 m), the Bannisdale Slates (5200 ft./1,600 m) and the Kirkby Moor Flags (2,000 ft./615 m).
In the Silurian areas of southern Scotland, the Ludlow rocks are represented in the Kirkcudbright Shore and Riccarton district by the Raeberry Castle beds and Balmae Grits (500-750 ft.). In the northern belt Lanarkshire and the Pentland Hillsthe lower portion (or Ludlovian) consists of mudstones, flaggy shales and greywackes; but the upper (or Downtonian) part is made up principally of thick red and yellow sandstones and conglomerates with green mudstones. The Ludlow rocks of Ireland include the ” Salrock beds ” of County Galway and the “Croagmarhin beds” of Dingle promontory.
Note : The above story is based on materials provided by Wikipedia
The Wenlock (seldomly also referred to as Wenlockian) is the second series of the Silurian. It is preceded by the Llandovery series and followed by the Ludlow. Radiometric dates constrain the Wenlockian between 433.4 ± 0.8 and 427.4 ± 0.5 million years ago.
Naming and history
The Wenlock is named after Wenlock Edge, an outcrop of rocks near the town of Much Wenlock in Shropshire (West Midlands, United Kingdom). The name was first used in the term “Wenlock and Dudley rocks” by Roderick Murchison in 1834 to refer to the limestones and underlying shales that underlay what he termed the “Ludlow rocks”. He later modified this term to simply the “Wenlock rocks” in his the Silurian System in 1839.
Definition and subdivision
The Wenlock’s beginning is defined by the lower boundary (or GSSP) of the Sheinwoodian. The end is defined as the base (or GSSP) of the Gorstian.
The Wenlock is divided into the older Sheinwoodian and the younger Homerian stage. The Sheinwoodian lasted from 433.4 ± 0.8 to 430.5 ± 0.7 million years ago. The Homerian lasted from 430.5 ± 0.7 to 427.4 ± 0.5 million years ago.
Note : The above story is based on materials provided by Wikipedia
In geology, the Llandovery Group refers to the lowest division of the Silurian period (Upper Silurian) in Britain. It is named after the town of Llandovery in Wales, although Charles Lapworth had proposed the name Valentian (from the Roman British province of Valentia) for this group in 1879. It includes the Tarannon Shales (1000-1500 ft.), Upper Llandovery and May Hill Sandstone (800 ft.), Lower Llandovery, (600-1500 ft.)
The Lower Llandovery rocks consist of conglomerates, sandstones and slaty beds. At Llandovery they rest upon Ordovician rocks. These rocks occur with a narrow crop in Pembrokeshire, which curves round through Llandovery, and in the Rhayader district they reach a considerable thickness. They also occur in Ceredigion and Carmarthenshire.
The Upper Llandovery has local lenticular developments of shelly limestone (Norbury, Hollies and Pentamerus limestones). It occurs with a narrow outcrop in Carmarthenshire at the base of the Silurian, disappearing beneath the Old Red Sandstone westward to reappear in Pembrokeshire; north-eastward the outcrop extends to the Long Mynd, which the conglomerate wraps round. As it is followed along the crop it rests upon the Lower Llandovery, Caradog, Llandeilo, Cambrian and pre-Cambrian rocks. The fossils include the trilobites Phacops caudata, Encrinurus punctatus and Calymene blumenbachis; the brachiopods Pentamerus oblongus, Orthis calligramma and Atrypa reticularis; the corals Favosites and Lindostroemia; and the zonal graptolites Rastriles maximus and Monograptus spinigerus.
The Tarannon shales, grey and blue slates, designated by Adam Sedgwick the Paste Rock, is traceable from Conwy into Carmarthenshire; in Ceredigion, there are gritty beds; and in the neighbourhood of Builth, soft dark shales. The group is poor in fossils, with the exception of graptolites; of these Cyrtograptus grayae and Monograptus exiguus are zonal forms. The Tarannon group is represented by the Rhayader Pale Shales in Powys; in the Moffat Silurian belt in south Scotland by a thick development, including the Hawick rocks and Ardwell Beds, and the Queensberry Group or Gala; in the Girvan area, by the Drumyork Flags, Bargany Group and Penkill Group; and in Ireland by the Treveshilly Shales of Strangford Lough, and the shales of Salterstown, Co. Louth.
The Upper and Lower Llandovery rocks are represented in descending order by the Pale Shales, Graptolite Shales, Grey Slates and Corwen Grit of Meirionnydd and Denbighshire. In the Lake district the lower part of the Stockdale shales (Skelgill beds) is of Llandovery age. In the Girvan area to the north their place is taken by the Camregan, Shaugh Hill and Mullock Hill groups. In Ireland the Llandovery rocks are represented by the Anascaul Slates of the Dingle promontory, by the Owenduff and Gowlaun Grits, Co. Galway, by the Upper Pomeroy Beds, by the Uggool and Ballaghaderin Beds, Co. Mayo, and by rocks of this age in Coalpit Bay and Slieve Felim Mountains.
Economic deposits in Llandovery rocks include slate pencils (Teesdale), building stone, flag-stone, road metal and lime.
Note : The above story is based on materials provided by Wikipedia
Chemical Formula: FeWO4
