Chemical Formula: (Fe,Mn)(Nb,Ta)2O6 Locality: Globe and Harding pegmatites, Taos County, New Mexico, USA. Name Origin: Named for the MANGANese content and the relationship to columbite (ferrocolumbite).
Columbite, also called niobite, niobite-tantalite and columbate [(Fe, Mn)Nb2O6], is a black mineral group that is an ore of niobium. It has a submetallic luster and a high density and is a niobate of iron and manganese. This mineral group was first found in Haddam, Connecticut, in the United States. It forms a series with the tantalum-dominant analogue ferrotantalite and one with the manganese-dominant analogue manganocolumbite. The iron-rich member of the columbite group is ferrocolumbite. Some tin and tungsten may be present in the mineral. Yttrocolumbite is the yttrium-rich columbite with the formula (Y,U,Fe)(Nb,Ta)O4. It is a radioactive mineral found in Mozambique.
Columbite has the same composition and crystal symmetry (orthorhombic) as tantalite. In fact, the two are often grouped together as a semi-singular mineral series called columbite-tantalite or coltan in many mineral guides. However, tantalite has a much greater specific gravity than columbite, more than 8.0 compared to columbite’s 5.2.
Smoke billows from a new island off the coast of Nishinoshima, a small, uninhabited island in the Ogasawara chain, far south of Tokyo Thursday, Nov. 21, 2013. The Japan Coast Guard and earthquake experts said a volcanic eruption has raised the new island in the seas to the far south of Tokyo. The coast guard issued an advisory Wednesday warning of heavy black smoke from the eruption. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT
A volcanic eruption has raised an island in the seas to the far south of Tokyo, the Japanese coast guard and earthquake experts said.
Advisories from the coast guard and the Japan Meteorological Agency said the islet is about 200 meters (660 feet) in diameter. It is just off the coast of Nishinoshima, a small, uninhabited island in the Ogasawara chain, which is also known as the Bonin Islands.
The approximately 30 islands are 1,000 kilometers (620 miles) south of Tokyo, and along with the rest of Japan are part of the seismically active Pacific “Ring of Fire.”
The coast guard issued an advisory Wednesday warning of heavy black smoke from the eruption. Television footage seen Thursday showed heavy smoke, ash and rocks exploding from the crater, as steam billowed into the sky.
A volcanologist with the coast guard, Hiroshi Ito, told the FNN news network that it was possible the new island might be eroded away.
“But it also could remain permanently,” he said.
The last time the volcanos in the area are known to have erupted was in the mid-1970s. Much of the volcanic activity occurs under the sea, which extends thousands of meters deep along the Izu-Ogasawara-Marianas Trench.
Smoke billows from a new island off the coast of Nishinoshima, seen left above, a small, uninhabited island in the Ogasawara chain, far south of Tokyo Thursday, Nov. 21, 2013. The Japan Coast Guard and earthquake experts said a volcanic eruption has raised the new island in the seas to the far south of Tokyo. The coast guard issued an advisory Wednesday warning of heavy black smoke from the eruption. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT
Japan’s chief government spokesman welcomed the news of yet another bit, however tiny, of new territory.”This has happened before and in some cases the islands disappeared,” Yoshihide Suga said when asked if the government was planning on naming the new island.
Graphic map showing the new islet created by a volcanic eruption in southern Japan
“If it becomes a full-fledged island, we would be happy to have more territory.”
Smoke billows from a new island off the coast of Nishinoshima, seen at bottom, a small, uninhabited island in the Ogasawara chain, far south of Tokyo Thursday, Nov. 21, 2013. The Japan Coast Guard and earthquake experts said a volcanic eruption has raised the new island in the seas to the far south of Tokyo. The coast guard issued an advisory Wednesday warning of heavy black smoke from the eruption. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT
The Japanese archipelago has thousands of islands. In some cases, they help anchor claims to wide expanses of ocean overlying potentially lucrative energy and mineral resources.
In this Wednesday, Nov. 20, 2013 photo released by Japan Coast Guard, smoke billows from a new island off the coast of Nishinoshima, seen left above, a small, uninhabited island in the Ogasawara chain, far south of Tokyo. The Japan Coast Guard and earthquake experts said a volcanic eruption has raised the new island in the seas to the far south of Tokyo. (AP Photo/Japan Coast Guard)
Japan has plans to build port facilities and transplant fast-growing coral fragments onto Okinotorishima, two rocky outcroppings even further south of Tokyo, to boost its claim in a territorial dispute with China.
Smoke billows from a new island off the coast of Nishinoshima, a small, uninhabited island in the Ogasawara chain, far south of Tokyo Thursday, Nov. 21, 2013. The Japan Coast Guard and earthquake experts said a volcanic eruption has raised the new island in the seas to the far south of Tokyo. The coast guard issued an advisory Wednesday warning of heavy black smoke from the eruption. (AP Photo/Kyodo News) JAPAN OUT, MANDATORY CREDIT
Note : The above story is based on materials provided by The Associated Press. All rights reserved.
AUSTIN, Texas — Researchers at The University of Texas at Austin have developed a simple scaling theory to estimate gas production from hydraulically fractured wells in the Barnett Shale. The method is intended to help the energy industry accurately identify low- and high-producing horizontal wells, as well as accurately predict how long it will take for gas reserves to deplete in the wells.
Using historical data from horizontal wells in the Barnett Shale formation in North Texas, Tad Patzek, professor and chair in the Department of Petroleum and Geosystems Engineering in the Cockrell School of Engineering; Michael Marder, professor of physics in the College of Natural Sciences; and Frank Male, a graduate student in physics, used a simple physics theory to model the rate at which production from the wells declines over time, known as the “decline curve.”
They describe their new model of the decline curve in the paper “Gas production in the Barnett Shale obeys a simple scaling theory,” published this week in the Proceedings of the National Academy of Sciences. To test their theory, the researchers analyzed 10 years of gas production data from the Barnett Shale licensed to the university by IHS CERA, a provider of global market and economic information.
The team’s estimates were an instrumental part of the comprehensive assessment of Barnett Shale reserves funded by the Alfred P. Sloan Foundation and issued earlier this year by the Bureau of Economic Geology at UT Austin.
Until now, estimates of shale gas production have primarily relied on models established for conventional oil and gas wells, which behave differently from the horizontal wells in gas-rich shales.
The researchers estimate the ultimate gas recovery from a sample of 8,294 horizontal wells in the Barnett Shale will be between 10 trillion and 20 trillion standard cubic feet (scf) during the lifetime of the wells. The study’s well sample is made up of about half of the 15,000 existing wells in the Barnett Shale, the geological formation outside Fort Worth that offers the longest production history for hydrofractured horizontal wells in the world.
“With our model at hand, you can better predict how much gas volume is left and how long it will take until that volume will be depleted,” Patzek said. “We are able to match historical production and predict future production of thousands of horizontal gas wells using this scaling theory.”
“The contributions of shale gas to the U.S. economy are so enormous that even small corrections to production estimates are of great practical significance,” Patzek said.
The researchers were surprised by how all of the wells they analyzed adhere to that simple scaling curve.
“By analyzing the basic physics underlying gas recovery from hydrofractured wells, we calculated a single curve that should describe how much gas comes out over time, and we showed that production from thousands of wells follows this curve,” Marder said.
Patzek adds: “We are able to predict when the decline will begin. Once decline sets in, gas production goes down rapidly.”
The decline of a well happens because of a process called pressure diffusion that causes pressure around a well to drop and gas production to decrease. The time at which gas pressure drops below its initial value everywhere in the rock between hydrofractures is called its interference time. On average, it takes five years for interference to occur, at which point wells produce gas at a far lower rate because the amount of gas coming out over time is proportional to the amount of gas remaining.
Using two parameters — a well’s interference time and the original gas in place — the researchers were able to determine the universal decline curve and extrapolate total gas production over time.
The researchers found that the scaling theory accurately predicted the behavior of approximately 2,000 wells in which production had begun to decrease exponentially within the past 10 years. The remaining wells were too young for the model to predict when decreases would set in, but the model enabled the researchers to estimate upper and lower production limits for well lifetime and the amount of gas that will be produced by the wells.
“For 2,057 of the horizontal wells in the Barnett Shale, interference is far enough advanced for us to verify that wells behave as predicted by the scaling form,” Patzek said. “The production forecasts will become more accurate as more production data becomes available.”
As a byproduct of their analysis, the researchers found that most horizontal wells for which predictions are possible underperform their theoretical production limits. The researchers have reached a tentative conclusion that many wells are on track to produce only about 10 percent of their potential.
The researchers conclude that well production could be greatly improved if the hydrofractures connected better to natural fractures in the surrounding rock. The process of hydraulic fracturing creates a network of cracks, like veins, in rocks that was previously impermeable, allowing gas to move. If there are high porosity and permeability within those connected cracks and hydrofractures, then a well is high producing. By contrast, if the connection with hydrofractures is weak, then a well is low producing.
“If this finding spurs research to understand why wells underperform, it may lead to improved production methods and eventually increase gas extraction from wells,” Marder said.
Work is underway on how to improve performance of hydrofractures in horizontal wells, Patzek added.
Note : The above story is based on materials provided by University of Texas at Austin
NASA’s Mars Reconnaissance Orbiter is providing new spectral “windows” into the diversity of Martian surface materials. Here in a volcanic caldera, bright magenta outcrops have a distinctive feldspar-rich composition. (Credit: NASA/JPL/JHUAPL/MSSS)
Researchers now have stronger evidence of granite on Mars and a new theory for how the granite — an igneous rock common on Earth — could have formed there, according to a new study. The findings suggest a much more geologically complex Mars than previously believed.
Large amounts of a mineral found in granite, known as feldspar, were found in an ancient Martian volcano. Further, minerals that are common in basalts that are rich in iron and magnesium, ubiquitous on Mars, are nearly completely absent at this location. The location of the feldspar also provides an explanation for how granite could have formed on Mars.
Granite, or its eruptive equivalent, rhyolite, is often found on Earth in tectonically active regions such as subduction zones. This is unlikely on Mars, but the research team concluded that prolonged magmatic activity on Mars can also produce these compositions on large scales.
“We’re providing the most compelling evidence to date that Mars has granitic rocks,” said James Wray, an assistant professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology and the study’s lead author.
The research was published November 17 in the Advance Online Publication of the journal Nature Geoscience. The work was supported by the NASA Mars Data Analysis Program.
For years Mars was considered geologically simplistic, consisting mostly of one kind of rock, in contrast to the diverse geology of Earth. The rocks that cover most of Mars’s surface are dark-colored volcanic rocks, called basalt, a type of rock also found throughout Hawaii for instance.
But earlier this year, the Mars Curiosity rover surprised scientists by discovering soils with a composition similar to granite, a light-colored, common igneous rock. No one knew what to make of the discovery because it was limited to one site on Mars.
The new study bolsters the evidence for granite on Mars by using remote sensing techniques with infrared spectroscopy to survey a large volcano on Mars that was active for billions of years. The volcano is dust-free, making it ideal for the study. Most volcanoes on Mars are blanketed with dust, but this volcano is being sand-blasted by some of the fastest-moving sand dunes on Mars, sweeping away any dust that might fall on the volcano. Inside, the research team found rich deposits of feldspar, which came as a surprise.
“Using the kind of infrared spectroscopic technique we were using, you shouldn’t really be able to detect feldspar minerals, unless there’s really, really a lot of feldspar and very little of the dark minerals that you get in basalt,” Wray said.
The location of the feldspar and absence of dark minerals inside the ancient volcano provides an explanation for how granite could form on Mars. While the magma slowly cools in the subsurface, low density melt separates from dense crystals in a process called fractionation. The cycle is repeated over and over for millennia until granite is formed. This process could happen inside of a volcano that is active over a long period of time, according to the computer simulations run in collaboration with Josef Dufek, who is also an associate professor in the School of Earth and Atmospheric Sciences at Georgia Tech.
“We think some of the volcanoes on Mars were sporadically active for billions of years,” Wray said. “It seems plausible that in a volcano you could get enough iterations of that reprocessing that you could form something like granite.”
This process is sometimes referred to as igneous distillation. In this case the distillation progressively enriches the melt in silica, which makes the melt, and eventual rock, lower density and gives it the physical properties of granite.
“These compositions are roughly similar to those comprising the plutons at Yosemite or erupting magmas at Mount St. Helens, and are dramatically different than the basalts that dominate the rest of the planet,” Dufek said.
Another study published in the same edition of Nature Geoscience by a different research team offers another interpretation for the feldspar-rich signature on Mars. That team, from the European Southern Observatory and the University of Paris, found a similar signature elsewhere on Mars, but likens the rocks to anorthosite, which is common on the moon. Wray believes the context of the feldspar minerals inside of the volcano makes a stronger argument for granite. Mars hasn’t been known to contain much of either anorthosite or granite, so either way, the findings suggest the Red Planet is more geologically interesting than before.
“We talk about water on Mars all the time, but the history of volcanism on Mars is another thing that we’d like to try to understand,” Wray said. “What kinds of rocks have been forming over the planet’s history? We thought that it was a pretty easy answer, but we’re now joining the emerging chorus saying things may be a little bit more diverse on Mars, as they are on Earth.”
This research is supported by the NASA Mars Data Analysis Program under award NNX13AH80G. Any conclusions or opinions are those of the authors and do not necessarily represent the official views of the sponsoring agencies.
Note : The above story is based on materials provided by Georgia Institute of Technology. The original article was written by Brett
The team analyzed amber samples from almost all well-known amber deposits worldwide. This amber originates from the Cretaceous period, an inclusion of foliage of the extinct conifer tree Parataxodium sp. from the Foremost Formation at Grassy Lake, Alberta, Canada. It is approximately 77 million years old. (Credit: Ryan C. McKellar)
An international team of researchers led by Ralf Tappert, University of Innsbruck, reconstructed the composition of Earth’s atmosphere of the last 220 million years by analyzing modern and fossil plant resins. The results suggest that atmospheric oxygen was considerably lower in Earth’s geological past than previously assumed. This new study questions some of the current theories about the evolution of climate and life, including the causes for the gigantism of dinosaurs.
Scientists encounter big challenges when reconstructing atmospheric compositions in Earth’s geological past because of the lack of useable sample material. One of the few organic materials that may preserve reliable data of Earth’s geological history over millions of years are fossil resins (e.g. amber). “Compared to other organic matter, amber has the advantage that it remains chemically and isotopically almost unchanged over long periods of geological time,” explains Ralf Tappert from the Institute of Mineralogy and Petrography at the University of Innsbruck. The mineralogist and his colleagues from the University of Alberta in Canada and universities in the USA and Spain have produced a comprehensive study of the chemical composition of Earth’s atmosphere since the Triassic period.
The study has been published in the journal Geochimica et Cosmochimica Acta. The interdisciplinary team, consisting of mineralogists, paleontologists and geochemists, use the preserving properties of plant resins, caused by polymerization, for their study. “During photosynthesis plants bind atmospheric carbon, whose isotopic composition is preserved in resins over millions of years, and from this, we can infer atmospheric oxygen concentrations,” explains Ralf Tappert. The information about oxygen concentration comes from the isotopic composition of carbon or rather from the ratio between the stable carbon isotopes 12C and 13C.
Atmospheric oxygen between 10 and 15 percent
The research team analyzed a total of 538 amber samples from from well-known amber deposits worldwide, with the oldest samples being approximately 220 million years old and recovered from the Dolomites in Italy. The team also compared fossil amber with modern resins to test the validity of the data. The results of this comprehensive study suggest that atmospheric oxygen during most of the past 220 million years was considerably lower than today’s 21 percent. “We suggest numbers between 10 and 15 percent,” says Tappert. These oxygen concentrations are not only lower than today but also considerably lower than the majority of previous investigations propose for the same time period. For the Cretaceous period (65 — 145 million years ago), for example, up to 30 percent atmospheric oxygen has been suggested previously.
Effects on climate and environment
The researchers also relate this low atmospheric oxygen to climatic developments in Earth’s history. “We found that particularly low oxygen levels coincided with intervals of elevated global temperatures and high carbon dioxide concentrations,” explains Tappert. The mineralogist suggests that oxygen may influence carbon dioxide levels and, under certain circumstances, might even accelerate the influx of carbon dioxide into the atmosphere. “Basically, we are dealing here with simple oxidation reactions that are amplified particularly during intervals of high temperatures such as during the Cretaceous period.” The researchers, thus, conclude that an increase in carbon dioxide levels caused by extremely strong vulcanism was accompanied by a decrease of atmospheric oxygen. This becomes particularly apparent when looking at the last 50 million years of geological history. Following the results of this study, the comparably low temperatures of the more recent past (i.e. the Ice Ages) may be attributed to the absence of large scale vulcanism events and an increase in atmospheric oxygen.
Oxygen may not be the cause of gigantism
According to the results of the study, oxygen may indirectly influence the climate. This in turn may also affect the evolution of life on Earth. A well-known example are dinosaurs: Many theories about animal gigantism offer high levels of atmospheric oxygen as an explanation. Tappert now suggests to reconsider these theories: “We do not want to negate the influence of oxygen for the evolution of life in general with our study, but the gigantism of dinosaurs cannot be explained by those theories.” The research team highly recommends conducting further studies and intends to analyze even older plant resins.
Note : The above story is based on materials provided by University of Innsbruck.
Mount Sidley, at the leading edge of the Executive Committee Range in Marie Byrd Land, is the last volcano in the chain that rises above the surface of the ice. But a group of seismologists has detected new volcanic activity under the ice about 30 miles ahead of Mount Sidley in the direction of the range’s migration. The new finding suggests that the source of magma is moving beyond the chain beneath the crust and the Antarctic Ice Sheet. (Credit: Doug Wiens)
It wasn’t what they were looking for but that only made the discovery all the more exciting.
In January 2010 a team of scientists had set up two crossing lines of seismographs across Marie Byrd Land in West Antarctica. It was the first time the scientists had deployed many instruments in the interior of the continent that could operate year-round even in the coldest parts of Antarctica.
Like a giant CT machine, the seismograph array used disturbances created by distant earthquakes to make images of the ice and rock deep within West Antarctica.
There were big questions to be asked and answered. The goal, says Doug Wiens, professor of earth and planetary science at Washington University in St. Louis and one of the project’s principle investigators, was essentially to weigh the ice sheet to help reconstruct Antarctica’s climate history. But to do this accurately the scientists had to know how Earth’s mantle would respond to an ice burden, and that depended on whether it was hot and fluid or cool and viscous. The seismic data would allow them to map the mantle’s properties.
In the meantime, automated-event-detection software was put to work to comb the data for anything unusual.
When it found two bursts of seismic events between January 2010 and March 2011, Wiens’ PhD student Amanda Lough looked more closely to see what was rattling the continent’s bones.
Was it rock grinding on rock, ice groaning over ice, or, perhaps, hot gases and liquid rock forcing their way through cracks in a volcanic complex?
Uncertain at first, the more Lough and her colleagues looked, the more convinced they became that a new volcano was forming a kilometer beneath the ice.
The discovery of the new as yet unnamed volcano is announced in the Nov. 17 advanced online issue of Nature Geoscience.
Following the trail of clues
The teams that install seismographs in Antarctica are given first crack at the data. Lough had done her bit as part of the WUSTL team, traveling to East Antarctica three times to install or remove stations in East Antarctica.
In 2010 many of the instruments were moved to West Antarctica and Wiens asked Lough to look at the seismic data coming in, the first large-scale dataset from this part of the continent.
“I started seeing events that kept occurring at the same location, which was odd, “Lough said. “Then I realized they were close to some mountains-but not right on top of them.”
“My first thought was, ‘Okay, maybe its just coincidence.’ But then I looked more closely and realized that the mountains were actually volcanoes and there was an age progression to the range. The volcanoes closest to the seismic events were the youngest ones.”
The events were weak and very low frequency, which strongly suggested they weren’t tectonic in origin. While low-magnitude seismic events of tectonic origin typically have frequencies of 10 to 20 cycles per second, this shaking was dominated by frequencies of 2 to 4 cycles per second.
Ruling out ice
But glacial processes can generate low-frequency events. If the events weren’t tectonic could they be glacial?
To probe farther, Lough used a global computer model of seismic velocities to “relocate” the hypocenters of the events to account for the known seismic velocities along different paths through the Earth. This procedure collapsed the swarm clusters to a third their original size.
It also showed that almost all of the events had occurred at depths of 25 to 40 kilometers (15 to 25 miles below the surface). This is extraordinarily deep — deep enough to be near the boundary between the earth’s crust and mantle, called the Moho, and more or less rules out a glacial origin.
It also casts doubt on a tectonic one. “A tectonic event might have a hypocenter 10 to 15 kilometers (6 to 9 miles) deep, but at 25 to 40 kilometers, these were way too deep,” Lough says.
A colleague suggested that the event waveforms looked like Deep Long Period earthquakes, or DPLs, which occur in volcanic areas, have the same frequency characteristics and are as deep. “Everything matches up,” Lough says.
An ash layer encased in ice
The seismologists also talked to Duncan Young and Don Blankenship of the University of Texas who fly airborne radar over Antarctica to produce topographic maps of the bedrock. “In these maps, you can see that there’s elevation in the bed topography at the same location as the seismic events,” Lough says.
The radar images also showed a layer of ash buried under the ice. “They see this layer all around our group of earthquakes and only in this area,” Lough says.
“Their best guess is that it came from Mount Waesche, an existing volcano near Mt Sidley. But that is also interesting because scientists had no idea when Mount Waesche was last active, and the ash layer is sets the age of the eruption at 8,000 years ago. ”
What’s up down there?
The case for volcanic origin has been made. But what exactly is causing the seismic activity?
“Most mountains in Antarctica are not volcanic,” Wiens says, “but most in this area are. Is it because East and West Antarctica are slowly rifting apart? We don’t know exactly. But we think there is probably a hot spot in the mantle here producing magma far beneath the surface.”
“People aren’t really sure what causes DPLs,” Lough says. “It seems to vary by volcanic complex, but most people think it’s the movement of magma and other fluids that leads to pressure-induced vibrations in cracks within volcanic and hydrothermal systems.”
Will the new volcano erupt?
“Definitely,” Lough says. “In fact because of the radar shows a mountain beneath the ice I think it has erupted in the past, before the rumblings we recorded.
Will the eruptions punch through a kilometer or more of ice above it?
The scientists calculated that an enormous eruption, one that released a thousand times more energy than the typical eruption, would be necessary to breach the ice above the volcano.
On the other hand a subglacial eruption and the accompanying heat flow will melt a lot of ice. “The volcano will create millions of gallons of water beneath the ice — many lakes full,” says Wiens. This water will rush beneath the ice towards the sea and feed into the hydrological catchment of the MacAyeal Ice Stream, one of several major ice streams draining ice from Marie Byrd Land into the Ross Ice Shelf.
By lubricating the bedrock, it will speed the flow of the overlying ice, perhaps increasing the rate of ice-mass loss in West Antarctica.
“We weren’t expecting to find anything like this,” Wiens says.
Note : The above story is based on materials provided by Washington University in St. Louis. The original article was written by Diana Lutz.
The remote site where scientists have discovered fossilised bacteria. Researchers say they have fresh evidence of the oldest life on Earth, with fossilised bacteria dating more than 3.5bn years. Photograph: David Wacey/AAP
Evidence of what could be the earliest forms of life on Earth has been unearthed in the remote Pilbara region of Western Australia.
Researchers from Australia and the US have discovered signs of “complex microbial ecosystems” within rock sediments dated at 3.5bn years old.
The microbes were found in a body of rock called the Dresser Formation, west of Marble Bar in WA.
Professor David Wacey, researcher at the University of Western Australia, told Guardian Australia the discovery “pushes back evidence of life on Earth by a few more million years”.
“The Pilbara has some of the best, least deformed rocks on Earth; there aren’t many rocks older than there,” he said. “I would say this is the most robust evidence of the oldest life on Earth. My team has found evidence dated at 3.45bn years in the past, so we have gone further back by a few million years.”
Wacey said slivers of rock were analysed by the team, which found evidence of groups of microbes within the sediment.
“Microbes and bacteria like to live in communities. Think about the bacteria in your stomach, for example,” he said. “These microbes lived in layers that required different chemical gradients to survive. So bacteria that liked light would be towards the top while those that didn’t were towards the bottom.”
Earth was a far different place 3.5bn years ago, with temperatures and sea levels much higher than today. Bacterial communities, such as that found in the Pilbara, were the most advanced form of life for several billion years before more complex life forms began to develop.
“Bacteria ruled the world back then, it would’ve been a very smelly world indeed,” said Wacey. “It would’ve been pretty hostile for us. There was essentially no oxygen, a lot of CO2 and methane and much warmer oceans.
“Most of the world was covered by water, with just a bit of land sticking out here and there. There was a lot of volcanic activity and plenty of sulphur in the air. Until 2.5bn years ago, there was only the start of the evolution that would see cells with nucleoli, then evolving to multi-cell organisms such as animals and us.”
Wacey said that the search for slightly older organisms would go on, potentially in ancient rock formations in South Africa and Greenland, but the Pilbara discovery could have further ramifications in the quest to learn more about the solar system.
“These kinds of ecosystems could be viewed by a rover, such as the one that visited Mars,” Wacey said. “We wouldn’t know the age, of course, as we couldn’t date them. But we would know that there was life at some point on another planet, which would be pretty exciting.”
Note : The above story is based on materials provided by Oliver Milman for the guardian
The researchers used the endocast of a Tyrannosaurus rex (pictured), an Allosaurus and the early bird Archaeopteryx. Photograph: Jim Zuckerman/Corbis
Scientists have created a detailed map of the dinosaur brain for the first time and found that the ancient beasts had the faculties for complex behaviour, and perhaps made sounds to communicate with one another.
The map provides an unprecedented view of the makeup of the dinosaur brain and a glimpse back in time at what the creatures might have been capable of during their reign on Earth millions of years ago.
“In the popular mind, dinosaurs may be underrated in the complexity of their behaviour,” said Erich Jarvis, who led the study at Duke University in North Carolina.
Soft tissues are not preserved in fossils, so researchers have had to infer the details of dinosaur brains from the faint impressions the organs leave on the insides of fossilised skulls. These “endocasts” give a sense of the size and shape of the outermost brain parts, but leave no clues about the brain’s deeper structures.
But now researchers have pieced together the innermost regions of the dinosaur brain, including six areas that are specialised for complex behaviour such as processing visual information and learning and making sounds.
Among other skills, the extinct beasts had sufficient brain complexity to communicate with sounds, Jarvis said. “But did it really happen? That we do not know.”
To recreate the dinosaur brain, the US researchers first studied the brains of alligators and birds. Alligators came from a lineage that predated many dinosaurs, while the first birds evolved afterwards. On that basis, Jarvis and his colleague Chun-Chun Chen argue that the dinosaur brain should have evolved to be somewhere in between.
The researchers drew up detailed maps of alligator and bird brains using a recently developed procedure that relies on gene activity varying across different parts of the brain. Though some genes are switched on in the brain all the time, others are activated only momentarily when something happens. This is the case for auditory regions of the brain, where genes are switched on in response to sounds.
To map the auditory regions of the brain, Jarvis quietened the animals down in a darkened room and then played bird songs to birds and alligator grunts to alligators. He then swiftly removed their brains, froze them, sliced them, and looked at the genes that had switched on in different regions.
The genetic information allowed Jarvis to make high-precision maps of bird and alligator brains, which showed the various regions and their organisation. To get the structure of the dinosaur brain he simply merged the two, and shaped the map to dinosaur brain proportions, which Chen worked out from the endocasts from Tyrannosaurus rex, an Allosaurus and the early bird Archaeopteryx.
The map of the dinosaur brain contained six regions, including one called the mesopallium involved in complex processing. “It suggests that the dinosaur brain had the capacity for complex sensory motor processing, just like we see in birds and alligators,” said Jarvis.
But while song birds learn tunes and sing them, Jarvis said, it was impossible to know whether dinosaurs were capable of a similar form of “vocal learning”.
“We don’t have any evidence that there was a dinosaur out there that did this, that shared vocal learning with songbirds. But all the brain subdivisions to support vocal learning are there, so I’d argue the capacity to evolve vocal learning did exist in dinosaurs,” he said. Jarvis described the study at the Society for Neuroscience meeting in San Diego.
“Because birds and alligators have this large cortex, it suggests that dinosaurs probably had a pretty big cortex too and were capable of pretty sophisticated behaviours,” said Michale Fee, who studies bird brains at MIT.
“It’s very unlikely that we’re ever going to find a dinosaur brain preserved anywhere, so the details are always going to have to be inferred. As we understand brain evolution better we’ll be able to make sharper speculations about what dinosaur brains might have looked like. But actually nailing it with real data is going to be hard,” he said.
Note : The above story is based on materials provided by Ian Sample, science correspondent, in San Diego for the guardian
The location of gold and nickel deposits on the WIS rings indicate its significance to the makeup of the Eastern Goldfields. Credit: Allan Rostron
The world’s largest and oldest meteorite impact structure has been discovered through research on the formation of gold deposits in WA’s Eastern Goldfields.
Located in the eastern Yilgarn, the Watchorn Impact Structure (WIS) is 560km in diameter at its widest point and estimated to be more than 2.6 billion years old.
Geologist Bob Watchorn says he has been analysing the structure using gravity and seismic databases since 1999 but has only recently discovered the prima facie evidence necessary to confirm its impact origin.
“I pinpointed where the rings should cut the roads … [and] you can see lines of hills heading perpendicular to the trend of hills in the eastern Yilgarn which is usually north-south,” he says.
“On the northern rings especially you can see large in situ shatter cones and striated rocks and various other prima facie evidence of a big impact.
“It was satisfying to find the prima facie evidence on the interpreted Landsat rings when I have had so many eminent geologists and geophysicists say that they couldn’t see any circular features.”
He says the link between mineral deposits and the rings of the WIS could impact mineral exploration in WA.
“I plotted all the gold and nickel mines [in the Eastern Goldfields] onto the Western Mining database,” he says.
“All of the big gold mines—I mean every single mine that was over one million ounces fell on the rings.
“If you’re going to go looking for deposits you should be looking in an entirely different location than what you would have before.”
He says careful analysis of the Yilgarn regional gravity data using small incremental changes to the sun angle dip and azimuth facilitated the discovery of the structure.
“I got the geophysicists to treat the databases in a very different way than what they normally treated it,” he says.
“I could see many concentric circular structures… at different levels of the lithosphere and then check them against seismic traverses that had been done.
“Eventually I was able to correlate different depth plans of the gravity data with the seismic data and noticed concentric bowl and dome shaped structures which correlated to the impact structures.”
He says the location of gold and nickel deposits on the rings are indicative of its significance to the makeup of the Eastern Goldfields.
“I know the gold deposits are 2.6 to 2.64 billion years old and they’ve actually formed on the rings,” he says.
“However the nickel formed 2.67 to 2.72 billion years ago and as most of the big nickel mines are on the rings there are still unanswered questions.
“It’s a paradigm-shifting discovery.”
Notes:
The Vredefort Crater, in South Africa, was previously thought to be the largest known impact structure at 300km in diameter and just over 2 billion years old
Shatter cones are rare geological structures known only to form beneath meteorite impact craters—they are evidence the rock has been subjected to significant pressure
Lithosphere—refers to the earth’s crust and upper mantle
Note : The above story is based on materials provided by Science Network WA
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period (521 million years ago), and they flourished throughout the lower Paleozoic era before beginning a drawn-out decline to extinction when, during the Devonian, all trilobite orders except Proetida died out. Trilobites finally disappeared in the mass extinction at the end of the Permian about 250 million years ago. The trilobites were among the most successful of all early animals, roaming the oceans for over 270 million years.
When trilobites first appeared in the fossil record they were already highly diverse and geographically dispersed. Because trilobites had wide diversity and an easily fossilized exoskeleton an extensive fossil record was left behind, with some 17,000 known species spanning Paleozoic time. The study of these fossils has facilitated important contributions to biostratigraphy, paleontology, evolutionary biology and plate tectonics. Trilobites are often placed within the arthropod subphylum Schizoramia within the superclass Arachnomorpha (equivalent to the Arachnata), although several alternative taxonomies are found in the literature.
Trilobites had many life styles; some moved over the sea-bed as predators, scavengers or filter feeders and some swam, feeding on plankton. Most life styles expected of modern marine arthropods are seen in trilobites, with the possible exception of parasitism (where there are still scientific debates). Some trilobites (particularly the family Olenidae) are even thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived food.
Fossil record
The earliest trilobites known from the fossil record are fallotaspids, and redlichiids (both order Redlichiida)
Redlichida, such as this Paradoxides, may represent the ancestral trilobites
.and bigotinids (order Ptychopariida, superfamily Ellipsocephaloidea) dated to some 540 to 520 million years ago. Contenders for the earliest trilobites include Profallotaspis jakutensis (Siberia), Fritzaspis spp. (western USA), Hupetina antiqua (Morocco) and Serrania gordaensis (Spain). All trilobites are thought to have originated in present day Siberia, with subsequent distribution and radiation from this location.
All Olenellina lack facial sutures (see below), and this is thought to represent the original state. The earliest sutured trilobite found so far (Lemdadella), occurs almost at the same time as the earliest Olenellina however, implying that trilobite origin lies before the start of the Atdabanian, but without leaving fossils. Other groups show secondary lost facial sutures, such as all Agnostina and some Phacopina. Another common feature of the Olenellina also suggests this suborder to be the ancestral trilobite stock: early protaspid stages have not been found, supposedly because these were not calcified, and this also is supposed to represent the original state. Earlier trilobites may be found and could shed more light on the origin of trilobites.
Origins
Early trilobites show all the features of the trilobite group as a whole; there do not seem to be any transitional or ancestral forms showing or combining the features of trilobites with other groups (e.g. early arthropods).
Morphological similarities between trilobites and early arthropod-like creatures such as Spriggina, Parvancorina, and other “trilobitomorphs” of the Ediacaran period of the Precambrian are ambiguous enough to make detailed analysis of their ancestry far from compelling. Morphological similarities between early trilobites and other Cambrian arthropods (e.g. the Burgess Shale fauna and the Maotianshan shales fauna) make analysis of ancestral relationships difficult.
However, it is still reasonable to assume that the trilobites share a common ancestor with other arthropods before the Ediacaran-Cambrian boundary. Evidence suggests that significant diversification had already occurred before trilobites were preserved in the fossil record, easily allowing for the “sudden” appearance of diverse trilobite groups with complex derived characteristics (e.g. eyes).
Divergence and extinction
For such a long-lasting group of animals, it is no surprise that trilobite evolutionary history is marked by a number of extinction events where some groups perished while surviving groups diversified to fill ecological niches with comparable or novel adaptations. Generally, trilobites maintained high diversity levels throughout the Cambrian and Ordovician periods before entering a drawn-out decline in the Devonian culminating in final extinction of the last few survivors at the end of the Permian period.
Evolutionary trends
Principal evolutionary trends from primitive morphologies (e.g. eoredlichids) include the origin of new types of eyes, improvement of enrollment and articulation mechanisms, increased size of pygidium (micropygy to isopygy) and development of extreme spinosity in certain groups. Changes also included narrowing of the thorax and increasing or decreasing numbers of thoracic segments. Specific changes to the cephalon are also noted; variable glabella size and shape, position of eyes and facial sutures & hypostome specialization. Several morphologies appeared independently within different major taxa (e.g. eye reduction or miniaturization).
Effacement is also a common evolutionary trend. It is the loss of surface detail in the cephalon, pygidium, or the thoracic furrows. Notable examples of this were the orders Agnostida, Asaphida, and the suborder Illaenina of Corynexochida. It is believed that effacement is an indication of either a burrowing lifestyle or a pelagic one. Effacement poses a problem for taxonomists since the loss of details (particularly of the Glabella) can make the determination of phylogenetic relationships difficult.
Pre-Cambrian
Phylogenetic biogeographic analysis of Early Cambrian Olenellidae and Redlichidae suggests that a uniform trilobite fauna existed over Laurentia, Gondwana and Siberia before the tectonic breakup of the super-continent Pannotia between 600 million years ago and 550 million years ago.Tectonic breakup of Pannotia then allowed for the diversification and radiation expressed later in the Cambrian as the distinctive olenellid province (Laurentia, Siberia and Baltica) and the separate Redlichid province (Australia, Antarctica and China). Breakup of Pannotia significantly predates the first appearance of trilobites in the fossil record, supporting a long and cryptic development of trilobites extending perhaps as far back as 700 million years ago or possibly further.
Cambrian
Very shortly after trilobite fossils appeared in the lower Cambrian, they rapidly diversified into the major orders that typified the Cambrian—Redlichiida, Ptychopariida, Agnostida and Corynexochida. The first major crisis in the trilobite fossil record occurred in the Middle Cambrian; surviving orders developed isopygus or macropygius bodies and developed thicker cuticles, allowing better defense against predators (see Thorax above). The end Cambrian mass extinction event marked a major change in trilobite fauna; almost all Redlichiida (including the Olenelloidea) and most Late Cambrian stocks went extinct. A continuing decrease in Laurentian continental shelf area is recorded at the same time as the extinctions, suggesting major environmental upheaval.
Ordovician
The Early Ordovician is marked by vigorous radiations of articulate brachiopods, bryozoans, bivalves,
Cheirurus sp., middle Ordovician age, Volkhov River, Russia
echinoderms, and graptolites with many groups appearing in the fossil record for the first time. Although intra-species trilobite diversity seems to have peaked during the Cambrian, trilobites were still active participants in the Ordovician radiation event with a new fauna taking over from the old Cambrian one.
Phacopida and Trinucleioidea are characteristic forms, highly differentiated and diverse, most with uncertain ancestors. The Phacopida and other “new” clades almost certainly had Cambrian forebears, but the fact that they have avoided detection is a strong indication that novel morphologies were developing very rapidly.
Changes within the trilobite fauna during the Ordovician foreshadowed the mass extinction at the end of the Ordovician allowing many families to continue into the Silurian with little disturbance. Ordovician trilobites were successful at exploiting new environments, notably reefs. However, the end Ordovician mass extinction did not leave the trilobites unscathed; some distinctive and previously successful forms such as the Trinucleioidea and Agnostida became extinct.
The Ordovician marks the last great diversification period amongst the trilobites, very few entirely new patterns of organisation arose post-Ordovician; later evolution in trilobites was largely a matter of variations upon the Ordovician themes. By the Ordovician mass extinction vigorous trilobite radiation has stopped and gradual decline beckons.
Silurian and Devonian
Phacopid trilobite, Devonian age , Ohio, United States
Most Early Silurian families constitute a subgroup of the Late Ordovocian fauna. Few, if any, of the dominant Early Ordovician fauna survived to the end of the Ordovician, yet 74% of the dominant Late Ordovician trilobite fauna survived the Ordovician. Late Ordovician survivors account for all post-Ordovician trilobite groups except the Harpetida.
Silurian and Devonian trilobite assemblages are superficially similar to Ordovician assemblages, dominated by Lichida and Phacopida (including the well-known Calymenina). However, a number of characteristic forms do not extend far into the Devonian and almost all the remainder were wiped out by a series of drastic Middle and Late Devonian extinctions. Three orders and all but five families were exterminated by the combination of sea level changes and a break in the redox equilibrium (a meteorite impact has also been suggested as a cause). Only a single order, the Proetida, survived into the Carboniferous.
Carboniferous and Permian
The Proetida survived for millions of years, continued through the Carboniferous period and lasted until the end of the Permian (when the vast majority of species on Earth were wiped out). It is unknown why order Proetida alone survived the Devonian. The Proetida maintained relatively diverse faunas in deep water and shallow water, shelf environments throughout the Carboniferous. For many millions of years the Proetida existed untroubled in their ecological niche. An analogy would be today’s crinoids, which mostly exist as deep water species; in the Paleozoic era, vast ‘forests’ of crinoids lived in shallow near-shore environments.
Final extinction
Exactly why the trilobites became extinct is not clear; with repeated extinction events (often followed by apparent recovery) throughout the trilobite fossil record, a combination of causes is likely. After the extinction event at the end of the Devonian period, what trilobite diversity remained was bottlenecked into the order Proetida. Decreasing diversity of genera limited to shallow water, shelf habitats coupled with a drastic lowering of sea level (regression) meant that the final decline of trilobites happened shortly before the end of the Permian mass extinction event. With so many marine species involved in the Permian extinction, the end of nearly 300 million successful years for the trilobite is hardly surprising.
The closest extant relatives of trilobites may be the horseshoe crabs, or the cephalocarids.
Fossil distribution
A trilobite fragment (T) in a thin-section of an Ordovician limestone; E=echinoderm; scale bar is 2 mm
Trilobites appear to have been exclusively marine organisms, since the fossilized remains of trilobites are always found in rocks containing fossils of other salt-water animals such as brachiopods, crinoids, and corals. Within the marine paleoenvironment, trilobites were found in a broad range from extremely shallow water to very deep water. Trilobites, like brachiopods, crinoids, and corals, are found on all modern continents, and occupied every ancient ocean from which Paleozoic fossils have been collected. The remnants of trilobites can range from the preserved body to pieces of the exoskeleton, which it sheds in the process known as ecdysis. In addition, the tracks left behind by trilobites living on the sea floor are often preserved as trace fossils.
There are three main forms of trace fossils associated with trilobites: Rusophycus; Cruziana & Diplichnites – such trace fossils represent the preserved life activity of trilobites active upon the sea floor. Rusophycus, the resting trace, are trilobite excavations involving little or no forward movement and ethological interpretations suggest resting, protection and hunting.Cruziana, the feeding trace, are furrows through the sediment, which are believed to represent the movement of trilobites while deposit feeding. Many of the Diplichnites fossils are believed to be traces made by trilobites walking on the sediment surface. However, care must be taken as similar trace fossils are recorded in freshwater and post Paleozoic deposits, representing non-trilobite origins.
Trilobite fossils are found worldwide, with many thousands of known species. Because they appeared quickly in geological time, and moulted like other arthropods, trilobites serve as excellent index fossils, enabling geologists to date the age of the rocks in which they are found. They were among the first fossils to attract widespread attention, and new species are being discovered every year.
A famous location for trilobite fossils in the United Kingdom is Wren’s Nest, Dudley in the West Midlands, where Calymene blumenbachi is found in the Silurian Wenlock Group. This trilobite is featured on the town’s coat of arms and was named the Dudley Bug or Dudley Locust by quarrymen who once worked the now abandoned limestone quarries. Llandrindod Wells, Powys, Wales, is another famous trilobite location. The well-known Elrathia kingi trilobite is found in abundance in the Cambrian age Wheeler Shale of Utah.
Spectacularly preserved trilobite fossils, often showing soft body parts (legs, gills, antennae, etc.) have been found in British Columbia, Canada (the Cambrian Burgess Shale and similar localities); New York State, U.S.A. (Ordovician Walcott-Rust quarry, near Russia, and Beecher’s Trilobite Bed, near Rome); China (Lower Cambrian Maotianshan Shales near Chengjiang); Germany (the Devonian Hunsrück Slates near Bundenbach) and, much more rarely, in trilobite-bearing strata in Utah (Wheeler Shale and other formations), Ontario, and Manuels River, Newfoundland and Labrador.The French palaeontologist Joachim Barrande (1799–1883) carried out his landmark study of trilobites in the Cambrian, Ordovician and Silurian of Bohemia, publishing the first volume of Système silurien du centre de la Bohême in 1852.
Morphology
The trilobite body is divided into three major sections (tagmata): 1 – cephalon; 2 – thorax; 3 – pygidium. Trilobites are so named for the three longitudinal lobes: 4 – right pleural lobe; 5 – axial lobe; 6 – left pleural lobe; the antennae and legs are not shown in these diagrams.
When trilobites are found, only the exoskeleton is preserved (often in an incomplete state) in all but a handful of locations. A few locations (Lagerstätten) preserve identifiable soft body parts (legs, gills, musculature & digestive tract) and enigmatic traces of other structures (e.g. fine details of eye structure) as well as the exoskeleton.
Trilobites range in length from 1 millimetre (0.04 in) to 72 centimetres (28 in), with a typical size range of 3–10 cm (1.2–3.9 in). The world’s largest trilobite, Isotelus rex, was found in 1998 by Canadian scientists in Ordovician rocks on the shores of Hudson Bay.
The exoskeleton is composed of calcite and calcium phosphate minerals in a protein lattice of chitin that covers the upper surface (dorsal) of the trilobite and curled round the lower edge to produce a small fringe called the “doublure”. Three distinctive tagmata (sections) are present: cephalon (head); thorax (body) and pygidium (tail).
Terminology
As might be expected for a group of animals comprising c. 5,000 genera, the morphology and description of trilobites can be complex. However, despite morphological complexity and an unclear position within higher classifications, there are a number of characteristics that distinguish the trilobites from other arthropods: a generally sub-elliptical, dorsal, chitinous exoskeleton divided longitudinally into three distinct lobes (from which the group gets its name); having a distinct, relatively large head shield (cephalon) articulating axially with a thorax comprising articulated transverse segments, the hindmost of which are almost invariably fused to form a tail shield (pygidium). When describing differences between trilobite taxa, the presence, size, and shape of the cephalic features are often mentioned.
During moulting, the exoskeleton generally split between the head and thorax, which is why so many trilobite fossils are missing one or the other. In most groups facial sutures on the cephalon helped facilitate moulting. Similar to lobsters and crabs, trilobites would have physically “grown” between the moult stage and the hardening of the new exoskeleton.
Cephalon
A trilobite’s cephalon, or head section, is highly variable with a lot of
The subdivisions can be further broken down into different areas used in describing trilobite cephalic morphology. 1 – preocular area; 2 – palpebral area; 3 – postocular area; 4 – posterolateral projection; 5 – occipital ring; 6 – glabella; 7 – posterior area; 8 – lateral border; 9 – librigenal area; 10 – preglabellar area
morphological complexity. The glabella forms a dome underneath which sat the “crop” or “stomach”. Generally the exoskeleton has few distinguishing ventral features, but the cephalon often preserves muscle attachment scars and occasionally the hypostome, a small rigid plate comparable to the ventral plate in other arthropods. A toothless mouth and stomach sat upon the hypostome with the mouth facing backwards at the rear edge of the hypostome.
Hypostome morphology is highly variable; sometimes supported by an un-mineralised membrane (natant), sometimes fused onto the anterior doublure with an outline very similar to the glabella above (conterminant) or fused to the anterior doublure with an outline significantly different from the glabella (impendent). Many variations in shape and placement of the hypostome have been described. The size of the glabella and the lateral fringe of the cephalon, together with hypostome variation, have been linked to different lifestyles, diets and specific ecological niches.
The anterior and lateral fringe of the cephalon is greatly enlarged in the Harpetida, in other species a bulge in the pre-glabellar area is preserved that suggests a brood pouch. Highly complex compound eyes are another obvious feature of the cephalon.
Facial sutures
Facial or Cephalic sutures are the natural fracture lines in the cephalon of trilobites. Their function was to assist the trilobite in shedding its old exoskeleton during ecdysis (or molting).
All species assigned to the suborder Olenellina, that went extinct at the very end of the Early Cambrian (like Fallotaspis, Nevadia, Judomia, and Olenellus) lacked facial sutures. They are believed to have never developed facial sutures, having pre-dated their evolution. Because of this (along with other primitive characteristics), they are thought to be the earliest ancestors of later trilobites.
Some other later trilobites also lost facial sutures secondarily. The type of sutures found in different species are used extensively in the taxonomy and phylogeny of trilobites.
Dorsal sutures
The dorsal surface of the trilobite cephalon (the frontmost tagma, or the ‘head’) can be divided into two regions – the cranidium and the librigena (“free cheeks”). The cranidium can be further divided into the glabella (the central lobe in the cephalon) and the fixigena (“fixed cheeks”). The facial sutures lie along the anterior edge, at the division between the cranidium and the librigena.
Trilobite facial sutures on the dorsal side can be roughly divided into five main types according to where the sutures end relative to the genal angle (the edges where the side and rear margins of the cephalon converge).
Absent– Facial sutures are lacking in the Olenellina. This is considered a primitive state, and is always combined with the presence of eyes.
Proparian – The facial suture ends in front of the genal angle, along the lateral margin. Example genera showing this type of suture include Dalmanites of Phacopina (Phacopida) and Ekwipagetia of Eodiscina (Agnostida).
Gonatoparian – The facial suture ends at the tip of the genal angle. Example genera showing this type of suture include Calymene and Trimerus of Calymenina (Phacopida).
Opisthoparian – The facial suture ends at the posterior margin of the cephalon. Example genera showing this type of suture include Peltura of Olenina (Ptychopariida) and Bumastus of Illaenina (Corynexochida). This is the most common type of facial suture.
Hypoparian or marginal – In some trilobites, dorsal sutures may be secondary lost. Several exemplary time series of species show the “migration” of the dorsal suture until it coincides with the margins of the cephalon. As the visual surface of the eye is on the diminishing free cheek (or librigena), the number of lenses tends to go down, and eventually the eye disappears. The loss of dorsal sutures may arise from the proparian state, such as in some Eodiscina like Weymouthia, all Agnostina, and some Phacopina such as Ductina. The marginal sutures exhibited by the harpetids and trinucleioids, however, are derived from opisthoparian sutures. On the other hand, blindness is not always accompanied by the loss of facial sutures.
Diagram showing the three kinds of facial sutures in trilobites
The primitive state of the dorsal sutures is proparian. Opisthoparian sutures have developed several times independently. There are no examples of proparian sutures developing in taxa with opisthoparian ancestry. Trilobites that exhibit opisthoparian sutures as adults commonly have proparian sutures as instars. Hypoparian sutures have also arisen independently in several groups of trilobites.
There are also two types of sutures in the dorsal surface connected to the compound eyes of trilobites.They are:
Ocular sutures – are sutures surrounding the edges of the compound eye. Trilobites with these sutures lose the entire surface of the eyes when molting. It is common among Cambrian trilobites.
Palpebral sutures – are sutures which form part of the dorsal facial suture running along the top edges of the compound eye.
Ventral sutures
Dorsal facial sutures continue downward to the ventral side of the cephalon where they become the Connective sutures that divide the doublure. The following are the types of ventral sutures.
Connective sutures – are the sutures that continue from the facial sutures past the front margin of the cephalon.
Rostral suture– is only present when the trilobite possesses a rostrum (or rostral plate). It connects the rostrum to the front part of the dorsal cranidium.
Hypostomal suture – separates the hypostome from the doublure when the hypostome is of the attached type. It is absent when the hypostome is free-floating (i.e. natant). it is also absent in some coterminant hypostomes where the hypostome is fused to the doublure.
Median suture – exhibited by asaphid trilobites, they are formed when instead of becoming connective sutures, the two dorsal sutures converge at a point in front of the cephalon then divide straight down the center of the doublure.
Rostrum
The rostrum (or the rostral plate) is a distinct part of the doublure located at the front of the cephalon. It is separated from the rest of the doublure by the rostral suture.
During molting in trilobites like Paradoxides, the rostrum is used to anchor the front part of the trilobite as the cranidium separates from the librigena. The opening created by the arching of the body provides an exit for the molting trilobite.
It is absent in some trilobites like Lachnostoma.
Hypostome
The hypostome is the hard mouthpart of the trilobite found on the ventral side of the cephalon typically below the glabella. The hypostome can be classified into three types based on whether they are permanently attached to the rostrum or not and whether they are aligned to the anterior dorsal tip of the glabella.
Natant– Hypostome not attached to doublure. Aligned with front edge of glabella.
Conterminant– Hypostome attached to rostral plate of doublure. Aligned with front edge of glabella.
Impendent – Hypostome attached to rostral plate but not aligned to glabella.
Below is an illustration of the three types. The doublure is shown in light gray, the inside surface of the cephalon in dark gray, and the hypostome in light blue. The glabella is outlined in red broken lines.
Thorax
The thorax is a series of articulated segments that lie between the cephalon and pygidium. The number of segments varies between 2 and 103 with most species in the 2 to 16 range.
Each segment consists of the central axial ring and the outer pleurae, which protected the limbs and gills. The pleurae are sometimes abbreviated or extended to form long spines. Apodemes are bulbous projections on the ventral surface of the exoskeleton to which most leg muscles attached, although some leg muscles attached directly to the exoskeleton. Determining a junction between thorax and pygidium can be difficult and many segment counts suffer from this problem.Trilobite fossils are often found “enrolled” (curled up) like modern pill bugs for protection; evidence suggests enrollment helped protect against the inherent weakness of the arthropod cuticle that was exploited by anomalocarid predators.
Some trilobites achieved a fully closed capsule (e.g. Phacops), while others with long pleural spines (e.g. Selenopeltis) left a gap at the sides or those with a small pygidium (e.g. Paradoxides) left a gap between the cephalon and pygidium. In Phacops, the pleurae overlap a smooth bevel (facet) allowing a close seal with the doublure. The doublure carries a Panderian notch or protuberance on each segment to prevent over rotation and achieve a good seal. Even in an agnostid, with only 2 articulating thoracic segments, the process of enrollment required a complex musculature to contract the exoskeleton and return to the flat condition.
Pygidium
The pygidium is formed from a number of segments and the telson fused together. Segments in the pygidium are similar to the thoracic segments (bearing biramous limbs) but are not articulated. Trilobites can be described based on the pygidium being micropygous (pygidium smaller than cephalon), subisopygous (pygidium sub equal to cephalon), isopygous (pygidium equal in size to cephalon), or macropygous (pygidium larger than cephalon).
Prosopon (surface sculpture)
Trilobite exoskeletons show a variety of small-scale structures collectively called prosopon. Prosopon does not include large scale extensions of the cuticle (e.g. hollow pleural spines) but to finer scale features, such as ribbing, domes, pustules, pitting, ridging and perforations. The exact purpose of the prosopon is not resolved but suggestions include structural strengthening, sensory pits or hairs, preventing predator attacks and maintaining aeration while enrolled. In one example, alimentary ridge networks (easily visible in Cambrian trilobites) might have been either digestive or respiratory tubes in the cephalon and other regions.
Spines
Koneprusia brutoni, an example of a species with elaborate spines from the Devonian Hamar Laghdad Formation, Alnif, Morocco
Some trilobites such as those of the order Lichida evolved elaborate spiny forms, from the Ordovician until the end of the Devonian period. Examples of these specimens have been found in the Hamar Laghdad Formation of Alnif in Morocco. There is, however, a serious counterfeiting and fakery problem with much of the Moroccan material that is offered commercially. Spectacular spined trilobites have also been found in western Russia; Oklahoma, USA; and Ontario, Canada.
Some trilobites had horns on their heads similar to those of modern beetles. Based on the size, location, and shape of the horns the most likely use of the horns was combat for mates, making the Asaphida family Raphiophoridae the earliest exemplars of this behavior. Another use for these spines was protection from predators. When enrolled, trilobite spines offered additional protection. This conclusion is likely to be applicable to other trilobites as well, such as in the Phacopid trilobite genus Walliserops, that developed spectacular tridents.
Soft body parts
Only 21 or so species are described from which soft body parts are preserved, so some features (e.g. the posterior antenniform cerci preserved only in Olenoides serratus) remain difficult to assess in the wider picture.
Appendages
Drawing of a biramous leg of Agnostus pisiformis
Trilobites had a single pair of preoral antennae and otherwise undifferentiated biramous limbs (2, 3 or 4 cephalic pairs, followed by one pair per thorax segment and some pygidium pairs). Each exopodite (walking leg) had 6 or 7 segments, homologous to other early arthropods. Exopodites are attached to the coxa, which also bore a feather-like endopodite, or gill branch, which was used for respiration and, in some species, swimming. The inside of the coxa (or gnathobase) carries spins, probably to chew prey items. The last exopodite segment usually had claws or spines. Many examples of hairs on the legs suggest adaptations for feeding (as for the gnathobases) or sensory organs to help with walking.
Digestive tract
The toothless mouth of trilobites was situated on the rear edge of the hypostome (facing backwards), in front of the legs attached to the cephalon. The mouth is linked by a small esophagus to the stomach that lay forward of the mouth, below the glabella. The “intestine” led backwards from there to the pygidium. The “feeding limbs” attached to the cephalon are thought to have fed food into the mouth, possibly “slicing” the food on the hypostome and/or gnathobases first. Alternative lifestyles are suggested, with the cephalic legs used to disturb the sediment to make food available. A large glabella, (implying a large stomach), coupled with an impendent hypostome has been used as evidence of more complex food sources, i.e. possibly a carnivorous lifestyle.
Internal organs
While there is direct and implied evidence for the presence and location of the mouth, stomach and digestive tract (see above) the presence of heart, brain and liver are only implied (although “present” in many reconstructions) with little direct geological evidence.
Musculature
Although rarely preserved, long lateral muscles extended from the cephalon to mid way down the pygidium, attaching to the axial rings allowing enrollment while separate muscles on the legs tucked them out of the way.
Sensory organs
Many trilobites had complex eyes; they also had a pair of antennae. Some trilobites were blind, probably living too deep in the sea for light to reach them. As such, they became secondarily blind in this branch of trilobite evolution. Other trilobites (e.g. Phacops rana and Erbenochile erbeni) had large eyes that were for use in more well lit, predator-filled waters.
Antennae
The pair of antennae suspected in most trilobites (and preserved in a few examples) were highly flexible to allow them to be retracted when the trilobite was enrolled. Also, one species (Olenoides serratus) preserves antennae-like cerci that project from the rear of the trilobite.
Eyes
Even the earliest trilobites had complex, compound eyes with lenses made of calcite (a characteristic of all trilobite eyes), confirming that the eyes of arthropods and probably other animals could have developed before the Cambrian. Improving eyesight of both predator and prey in marine environments has been suggested as one of the evolutionary pressures furthering an apparent rapid development of new life forms during what is known as the Cambrian Explosion.
Trilobite eyes were typically compound, with each lens being an elongated prism. The number of lenses in such an eye varied: some trilobites had only one, while some had thousands of lenses in a single eye. In compound eyes, the lenses were typically arranged hexagonally. The fossil record of trilobite eyes is complete enough that their evolution can be studied through time, which compensates to some extent the lack of preservation of soft internal parts.Lenses of trilobites’ eyes were made of calcite (calcium carbonate, CaCO3). Pure forms of calcite are transparent, and some trilobites used crystallographically oriented, clear calcite crystals to form each lens of each of their eyes. Rigid calcite lenses would have been unable to accommodate to a change of focus like the soft lens in a human eye would; however, in some trilobites the calcite formed an internal doublet structure, giving superb depth of field and minimal spherical aberration, according to optical principles discovered by French scientist René Descartes and Dutch physicist Christiaan Huygens in the 17th century. A living species with similar lenses is the brittle star Ophiocoma wendtii.
In other trilobites, with a Huygens interface apparently missing, a gradient index lens is invoked with the refractive index of the lens changing towards the center.
Holochroal eyes had a great number (sometimes over 15,000) of small (30–100 μm, rarely larger) lenses. Lenses were hexagonally close packed, touching each other, with a single corneal membrane covering all lenses. Holochroal eyes had no sclera, the white layer covering the eyes of most modern arthropods. Holochroal eyes are the ancestral eye of trilobites, and are by far the most common, found in all orders except the Agnostida, and through the entirety of the Trilobites’ existence. Little is known of the early history of holochroal eyes; Lower and Middle Cambrian trilobites rarely preserve the visual surface. The spatial resolving power of grated eyes (such as holochroal eyes) is dependent on light intensity, circular motion, receptor density, registered light angle, and the extent to which the signal of individual rhabdoms are neurally combined. This implies that lenses need to be larger under low light conditions (such as for Pricyclopyge, when comparing it to Carolinites), and for fast moving predators and prey. As the circular velocity caused by the forward speed of an animal itself is much higher for the ommatidia directed perpendicular to the movement, fast-moving trilobites (such as Carolinites) have eyes flattened from the side and more curved were ommatia are directed to front, back, up and down. Thus eye morphology can be used to make assumptions about the ecosystem of trilobites.
Schizochroal eyes typically had fewer (around 700), larger lenses than holochroal eyes and are found only in Phacopida. Lenses were separate, with each lens having an individual cornea that extended into a rather large sclera. Schizochroal eyes appear quite suddenly in the early Ordovician, and were presumably derived from a holochroal ancestor. Field of view (all around vision), eye placement and coincidental development of more efficient enrollment mechanisms point to the eye as a more defensive “early warning” system than directly aiding in the hunt for food. Modern eyes that are functionally equivalent to the schizochroal eye were not thought to exist, but are found in the modern insect species Xenos peckii.
Abathochroal eyes are found only in Cambrian Eodiscina, and have around 70 small separate lenses that had individual cornea. The sclera was separate from the cornea, and did not run as deep as the sclera in schizochroal eyes. Although well preserved examples are sparse in the early fossil record, abathochroal eyes have been recorded in the lower Cambrian, making them among the oldest known. Environmental conditions seem to have resulted in the later loss of visual organs in many Eodiscina.
Secondary blindness is not uncommon, particularly in long lived groups such as the Agnostida and Trinucleioidea. In Proetida and Phacopina from western Europe and particularly Tropidocoryphinae from France (where there is good stratigraphic control), there are well studied trends showing progressive eye reduction between closely related species that eventually leads to blindness.
Several other structures on trilobites have been explained as photo-receptors. Of particular interest are “macula”, the small areas of thinned cuticle on the underside of the hypostome. In some trilobites macula are suggested to function as simple “ventral eyes” that could have detected night and day or allowed a trilobite to navigate while swimming (or turned) upside down.
Sensory pits
There are several types of prosopon that have been suggested as sensory apparatus collecting chemical or vibrational signals. The connection between large pitted fringes on the cephalon of Harpetida and Trinucleoidea with corresponding small or absent eyes makes for an interesting possibility of the fringe as a “compound ear”.
Development
Trilobites grew through successive moult stages called instars, in which existing segments increased in size and new trunk segments appeared at a sub-terminal generative zone during the anamorphic phase of development. This was followed by the epimorphic developmental phase, in which the animal continued to grow and moult, but no new trunk segments were expressed in the exoskeleton. The combination of anamorphic and epimorphic growth constitutes the hemianamorphic developmental mode that is common among many living arthropods.
Elrathia kingii growth series with holaspids ranging from 16.2 mm to 39.8 mm in length
Trilobite development was unusual in the way in which articulations developed between segments, and changes in the development of articulation gave rise to the conventionally recognized developmental phases of the trilobite life cycle (divided into 3 stages), which are not readily compared with those of other arthropods. Actual growth and change in external form of the trilobite would have occurred when the trilobite was soft shelled, following moulting and before the next exoskeleton hardened.
Trilobite larvae are known from the Cambrian to the Carboniferous and from all sub-orders. As instars from closely related taxa are more similar than instars from distantly related taxa, trilobite larvae provide morphological information important in evaluating high-level phylogenetic relationships among trilobites.
Despite the absence of supporting fossil evidence, their similarity to living arthropods has led to the belief that trilobites multiplied sexually and produced eggs. Some species may have kept eggs or larvae in a brood pouch forward of the glabella, particularly when the ecological niche was challenging to larvae. Size and morphology of the first calcified stage are highly variable between (but not within) trilobite taxa, suggesting some trilobites passed through more growth within the egg than others. Early developmental stages prior to calcification of the exoskeleton are a possibility (suggested for fallotaspids), but so is calcification and hatching coinciding.
The earliest post-embryonic trilobite growth stage known with certainty are the “protaspid” stages (anamorphic phase). Starting with an indistinguishable proto-cephalon and proto-pygidium (anaprotaspid) a number of changes occur ending with a transverse furrow separating the proto-cephalon and proto-pygidium (metaprotaspid) that can continue to add segments. Segments are added at the posterior part of the pygidium but, all segments remain fused together.
The “meraspid” stages (anamorphic phase) are marked by the appearance of an articulation between the head and the fused trunk. Prior to the onset of the first meraspid stage the animal had a two-part structure — the head and the plate of fused trunk segments, the pygidium. During the meraspid stages, new segments appeared near the rear of the pygidium as well as additional articulations developing at the front of the pygidium, releasing freely articulating segments into the thorax. Segments are generally added one per moult (although two per moult and one every alternate moult are also recorded), with number of stages equal to the number of thoracic segments. A substantial amount of growth, from less than 25% up to 30%–40%, probably took place in the meraspid stages.
The “holaspid” stages (epimorphic phase) commence when a stable, mature number of segments has been released into the thorax. Moulting continued during the holaspid stages, with no changes in thoracic segment number. Some trilobites are suggested to have continued moulting and growing throughout the life of the individual, albeit at a slower rate on reaching maturity.Some trilobites showed a marked transition in morphology at one particular instar, which has been called “trilobite metamorphosis”. Radical change in morphology is linked to the loss or gain of distinctive features that mark a change in mode of life. A change in lifestyle during development has significance in terms of evolutionary pressure, as the trilobite could pass through several ecological niches on the way to adult development and changes would strongly affect survivorship and dispersal of trilobite taxa. It is worth noting that trilobites with all protaspid stages solely planktonic and later meraspid stages benthic (e.g. asaphids) failed to last through the Ordovician extinctions, while trilobites that were planktonic for only the first protaspid stage before metamorphosing into benthic forms survived (e.g. lichids, phacopids). Pelagic larval life-style proved ill-adapted to the rapid onset of global climatic cooling and loss of tropical shelf habitats during the Ordovician.
Note : The above story is based on materials provided by Wikipedia
A new discovery by researchers from the University of Notre Dame’s Department of Civil and Environmental Engineering and Earth Sciences could change prevailing assumptions about the chemical makeup of the Earth’s mantle.
Antonio Simonetti, an associate professor in the department, and his doctoral student Wei Chen worked in cooperation with Vadim Kamenetsky of the University of Tasmania, Hobart (Australia) to learn the art of conducting chemical and mineralogical analyses of melt inclusions within crystals of the mineral magnetite (Fe3O4).
Simonetti points out that the magnetite crystals are hosted within igneous rocks (rocks resulting from the melting of the Earth’s mantle) referred to as carbonatites.
“The latter are an exceptional and intriguing type of igneous rock since they are composed primarily of calcium carbonate, or Calcite-CaCO3, rather than silicate minerals, which are the predominant minerals in the Earth’s crust and oceanic rocks,” Simonetti said. “Despite the small number of carbonatite occurrences worldwide compared to their volcanic counterparts in the past and present day, carbonatites continue to receive considerable deserved attention because of their unique enrichment, relative to crustal abundances in incompatible trace elements, such as niobium and the rare Earth elements.”
To date, most of the geological community believed that the sodium- and potassium-rich magmas being erupted at the Earth’s sole active carbonatite volcano at Ol Doinyo Lengai in Tanzania were unique, since all other carbonatite occurrences worldwide are dominated by calcium-rich carbonate or calcite.
In an attempt to resolve this question, Wei sought to determine the initial melt composition that gave rise to the Oka carbonatite complex, which is located in southeastern Quebec.
“We approached this issue by examining the nature and chemical composition of melt inclusions within individual magnetite crystals present in carbonatites,” Simonetti said. “Melt inclusions are micron-sized ‘pockets’ present within minerals that represent a combination or mechanical mixture of co-trapped crystals and melt engulfed and isolated early in the crystallization history of the magma while the magnetite crystals were forming. Hence, investigating melt inclusions represents a powerful tool for determining the chemical composition of the initial carbonatite magma at the Oka complex.”
Wei and Simonetti’s research revealed that the chemical composition of minerals trapped within the melt inclusions at the Oka complex are alkaline in nature and similar in composition to the minerals present at Ol Doinyo Lengai volcano. The finding will have a major impact in relation to deciphering and modeling chemical processes taking place in the Earth’s mantle throughout geologic time.
“This has some significant consequences as to how earth scientists should view the overall chemical budget of the Earth’s mantle since this is where carbonatite magmas are produced,” Simonetti said. “We are not attributing enough alkalies in the region of the mantle where carbonitite melts form.”
In addition to its significance for the field of earth science, the finding also has important practical and strategic importance. Carbonatites are of critical importance in the continually evolving fields of superconductors, electronics and computing. Several countries such as the USA, China, Brazil and Canada are host to carbonatite occurrences, and there is active exploration in many of these countries to locate new deposits given the ever-increasing demand for the manufacturing of sophisticated electronic components.
The paper describing Wei and Simonetti’s research appears in the journal Nature Communications.
Note : The above story is based on materials provided by University of Notre Dame
A rock surface is displaying “polygonal oscillation cracks” in the 3.48 billion years old Dresser Formation, Pilbara region, Western Australia. Such and similar sedimentary structures are of biological origin. They document ancient microorganisms that formed carpet-like microbial mats on the former sediment surface. The Dresser Formation records an ancient playa-like setting — similar environments are occurring on Mars as well. The MISS constitute a novel approach to detect and to understand Earth’s earliest life. (Credit: Nora Noffke)
Reconstructing the rise of life during the period of Earth’s history when it first evolved is challenging. Earth’s oldest sedimentary rocks are not only rare, but also almost always altered by hydrothermal and tectonic activity. A new study from a team including Carnegie’s Nora Noffke, a visiting investigator, and Robert Hazen revealed the well-preserved remnants of a complex ecosystem in a nearly 3.5 billion-year-old sedimentary rock sequence in Australia.
Their work is published in Astrobiology.
The Pilbara district of Western Australia constitutes one of the famous geological regions that allow insight into the early evolution of life. Mound-like deposits created by ancient photosynthetic bacteria, called stromatolites, and microfossils of bacteria have been described by scientists in detail. However, a phenomenon called microbially induced sedimentary structures, or MISS, had not previously been seen in this region. These structures are formed from mats of microbial material, much like mats seen today on stagnant waters or in coastal flats.
The team included Noffke, Hazen, Daniel Christian of Old Dominion University, and David Wacey of the University of Western Australia. They described various MISS preserved in the region’s Dresser Formation. Advanced chemical analyses point toward a biological origin of the material. The Dresser MISS fossils resemble strongly in form and preservation the MISS from several other younger rock samples, such as a 2.9 billion-year-old ecosystem Noffke and her colleagues found in South Africa.
“This work extends the geological record of MISS by almost 300 million years,” said Noffke, who is also a professor at ODU. “Complex mat-forming microbial communities likely existed almost 3.5 billion years ago.”
The team proposes that the sedimentary structures arose from the interactions of bacterial films with shoreline sediments from the region.
“The structures give a very clear signal on what the ancient conditions were, and what the bacteria composing the biofilms were able to do,” Noffke said.
MISS are among the targets of Mars rovers, which search for similar formations on that planet’s surface. Thus, the team’s findings could have relevance for studies of our larger Solar System as well.
Note : The above story is based on materials provided by Carnegie Institution.
New insights gleaned from volcanic rock are helping scientists better understand how our planet evolved billions of years ago.
Studies of basalt, the material that forms from cooling lava, are being used to develop a timeline of how the planet and its atmosphere were formed.
Scientists examined liquid basalt – or magma – at record high pressures and temperatures. Their findings suggest molten magma once formed an ocean within the Earth’s mantle, comprising two layers of fluid separated by a crystalline layer.
Scientists agree that Earth formed around 4.5 billion years ago, at which time much of the planet was molten. As it cooled, Earth’s crust was formed. Researchers are keen to pin down how the planet’s core and crust took shape and how its volcanic activity developed.
The discovery by a European team of scientists involving the University of Edinburgh, using hi-tech laboratories, supports current theories of how and when our planet evolved. To recreate conditions at the Earth’s core, scientists placed basalt under pressures equivalent to almost one billion times that of Earth’s atmosphere and temperatures above 2000 Celsius.
They found that at high pressure, silicon atoms in the basalt change the way in which they form bonds, which results in a denser magma. Their discovery helps pinpoint how magma behaves deep in the Earth and is a missing piece in the puzzle of how Earth’s core formed.
The study, published in Nature, was supported by the Scottish Universities Physics Alliance and European Research Council and carried out with the DESY Photon Science facility at Hamburg, the Universite Pierre et Marie Curie in Paris, Vrije Universitat Amsterdam, and Goethe-Universitat Frankfurt.
Dr Chrystele Sanloup, of the University of Edinburgh’s School of Physics and Astronomy, who took part in the study, said: “Modern labs make it possible for scientists to recreate conditions deep in the Earth’s core, and give us valuable insight into how materials behave at such extremes. This helps us build on what we already know about how Earth formed.”
Note : The above story is based on materials provided by University of Edinburgh
Fault scarps like this one in Italy’s central Apennine Mountains have allowed researchers to understand how the lower crust, nine miles below, influences earthquakes. Credit: Joanna Faure Walker, University College London
Most earthquakes erupt suddenly from faults near Earth’s surface, and the big ones can topple cities. But miles below, rocks heated to the consistency of wax moving over thousands to millions of years may be the driving force behind some of these events. In a new study in the journal Nature Geoscience, scientists link rapid-fire destruction on the surface to the hyper-slow flow of rocks in Earth’s lower crust. The study also shows that the weight of overlying mountains causes these deep rocks to strain at a rate that determines the frequency of large earthquakes on overlying faults; the scientists say that this relationship follows simple mathematical laws that were known from lab experiments.
“This tells us that the earthquake-prone faults in the shallow part of the crust are directly rooted into the flowing material at depth,” said the study’s lead author, Patience Cowie, a geologist at the University of Bergen in Norway.
The study is based on measurements taken from Italy’s earthquake-prone Apennine Mountains, where a magnitude 6.3 earthquake in L’Aquila in 2009 killed more than 300 people. The Apennines bear scars from past seismic activity in the form of fault scarps, marking where land has slipped down on the faults. Working in the central and southern Apennines, Gerald Roberts and Joanna Faure Walker, geologists at University College London, measured how much the scarps had moved, and in which direction, to reconstruct deformation rates over the past 10,000 years.
Their results, presented at a conference in Greece in 2011, caught the eye of study coauthor Christopher Scholz, a geophysicist at Columbia University’s Lamont-Doherty Earth Observatory. At each fault, Scholz noticed that elevation appeared closely linked to the deformation rate, suggesting that the gradual flow of deep crust, more than nine miles down, was placing strain on the fault. The researchers hypothesize that stress from the weight of the mountains cause shear zones in the deep crust to deform, determining how often the fault will slip to produce earthquakes. The deformation rate data from the Apennines closely matched that from lab experiments showing that rocks in deep shear zones strain at a rate proportional to the cube of the stress.
“The higher the elevation, the faster the faults are sliding,” said Scholz. “As long as you’re pushing up on the mountains, they grow, but they always want to collapse because of gravitational forces. After the tectonics that’s pushing them stops, as in the Apennines, they collapse under their own weight.”
A related conclusion is that a doubling of the topographic elevation corresponds to an eight-fold increase in the deformation rate. That means faults located in lower elevation areas that have not ruptured in historical times may still be active but with longer periods of inactivity between earthquakes due to their lower deformation rate.
The study offers an elegant way to understand the nature of deformation in the lower crust and how it influences earthquakes, said Roland Bürgmann, a geophysicist at the University of California at Berkeley who was not involved in the research. “To understand the real world, we need to simplify it, which they do by making a lot of assumptions, but it does look like an intriguing relationship,” he said.
It is unclear if the researchers’ model can be fully applied to other earthquake-prone areas. Other mountain belts like the Himalayas are being deformed by horizontal stresses and are still in the mountain-building phase, while the Apennines are currently collapsing under the action of vertical stresses. Still, the Apennines have allowed researchers to discover how the deep crust behaves which can be applied anywhere, said Scholz.
Note : The above story is based on materials provided by Columbia University
This image shows a holotype male, on the right, and allotype female, on the left. (Credit: Li S, Shih C, Wang C, Pang H, Ren D)
Scientists have found the oldest fossil depicting copulating insects in northeastern China, published November 6th in the open-access journal PLOS ONE by Dong Ren and colleagues at the Capital Normal University in China.
Fossil records of mating insects are fairly sparse, and therefore our current knowledge of mating position and genitalia orientation in the early stages of evolution is rather limited.
In this study, the authors present a fossil of a pair of copulating froghoppers, a type of small insect that hops from plant to plant much like tiny frogs. The well-preserved fossil of these two froghoppers showed belly-to-belly mating position and depicts the male reproductive organ inserting into the female copulatory structure.
This is the earliest record of copulating insects to date, and suggests that froghoppers’ genital symmetry and mating position have remained static for over 165 million years. Ren adds, “We found these two very rare copulating froghoppers which provide a glimpse of interesting insect behavior and important data to understand their mating position and genitalia orientation during the Middle Jurassic.”
Note : The above story is based on materials provided by Public Library of Science.
The lava flow steaming after rain. Credit: Image courtesy of Lancaster University
Scientists have made the first ever observations of how a rare type of lava continues moving almost a year after a volcanic eruption.
Researchers visiting the Puyehue-Cordón Caulle volcano in Chile in January this year found the obsidian lava flow was still moving, even though the volcano stopped erupting in April 2012.
The research by an international team of scientists, led by Dr Hugh Tuffen and Dr Mike James from the Lancaster Environment Centre at Lancaster University, is published in Nature Communications.
Obsidian lava is very thick and can barely flow, moving more like a glacier. This type of lava, rich in silica, forms a natural glass called obsidian when it cools and solidifies. This volcanic glass slowly inches forward as a thick, shattering crust of black rock that covers the oozing lava within.
Dr Tuffen said: “We found out that the lava was still oozing after almost a year and it advances between 1 and 3 metres a day. Although it moves slowly, it could speed up or collapse if it were to reach a steep hill, and The team, which included Professor Jon Castro from the University of Mainz and Dr Ian Schipper from the Victoria University of Wellington, also made new discoveries about how the obsidian lava flows, pointing the way towards a new model of how lavas advance.
Dr Tuffen said: “It looks like a solid cliff of crumbling rock up to 40 metres thick, that’s as thick as ten double-decker buses, but we found that hidden beneath this crust there is hot, slowly-flowing lava, at up to 900 °C, which can burst out of the edges of the lava flow and help it move forwards. This was previously thought to only occur in hot red flowing or basalt lava, but we have found that thick obsidian lava is actually pretty similar to its runnier cousins.”
Although seldom seen, obsidian lava can be erupted at the end of some of the largest and most explosive eruptions on Earth, including supervolcanoes such as Yellowstone and the largest eruption of the 20th century, at Katmai in Alaska. However, the most recent opportunities to see obsidian lava moving have been the last three eruptions at Puyehue-Cordón Caulle volcano in Chile in 2011, 1960 and 1921. Obsidian from lava flows is strewn over many archaeological sites worldwide, as it was long a highly-prized and traded material used for knives, arrowheads and cutting tools. It still has surgical applications due to its remarkably sharp cutting edges.
Dr Tuffen is funded by the Royal Society.
Video
Note : The above story is based on materials provided by Lancaster University.
This skull, which includes pieces of real fossil, shows the unique features of this new tyrannosaur. (Credit: Mark Loewen, NHMU)
A remarkable new species of tyrannosaur has been unearthed in Grand Staircase-Escalante National Monument (GSENM), southern Utah. The huge carnivore inhabited Laramidia, a landmass formed on the western coast of a shallow sea that flooded the central region of North America, isolating western and eastern portions of the continent for millions of years during the Late Cretaceous Period, between 95-70 million years ago. The newly discovered dinosaur, belonging to the same evolutionary branch as the famous Tyrannosaurus rex, was announced today in the open-access scientific journal PLOS ONE and unveiled on exhibit in the Past Worlds Gallery at the Natural History Museum of Utah at the Rio Tinto Center in Salt Lake City, Utah.
Among tyrannosaurs, a group of small to large-bodied, bipedal carnivorous dinosaurs including T. rex that lived during the Jurassic and Cretaceous periods, the newly discovered species, Lythronax argestes, possesses several unique features, a short narrow snout with a wide back of the skull with forward-oriented eyes. Lythronax translates as “king of gore,” and the second part of the name, argestes, refers to its geographic location in the American Southwest. Previously, paleontologists thought this type of wide-skulled tyrannosaurid only appeared 70 million years ago, whereas Lythronax shows it had evolved at least 10 million years earlier.
The study, funded in large part by the Bureau of Land Management and the National Science Foundation, was led by Dr. Mark Loewen, research associate at the Natural History Museum of Utah, and adjunct assistant professor in the Department of Geology and Geophysics at the University of Utah. Additional collaborative authors include Dr. Randall Irmis (Natural History Museum of Utah and Dept. of Geology and Geophysics, University of Utah), Dr. Joseph Sertich (Denver Museum of Nature & Science), Dr. Philip Currie (University of Alberta), and Dr. Scott Sampson (Denver Museum of Nature & Science). The skeleton was discovered by BLM employee Scott Richardson, and excavated by a joint NHMU-GSENM team.
Lythronax lived on Laramidia, along the western shores of the great seaway that separated North America; this landmass hosted a vast array of unique dinosaur species and served as the crucible of evolution for iconic dinosaur groups such as the horned and duck billed dinosaurs. This study also indicates that tyrannosaurid dinosaurs (the group of tyrannosaurs that includes T. rex) likely evolved in isolation on this island continent. Lythronax stands out from its contemporaries in having a much wider skull at the eyes and a narrow short snout, similar to its relative T. rex, which lived 10-12 million years later. Dr. Mark Loewen, the study’s lead author, noted, “The width of the back of the skull of Lythronax allowed it to see with an overlapping field of view — giving it the binocular vision — very useful for a predator and a condition we associate with T. rex.” Previously, paleontologists thought this type of wide-skulled tyrannosaurid only appeared ~70 million years ago, whereas Lythronax shows it had evolved at least 10 million years earlier
Paleontologists have recently determined that the dinosaurs of southern Laramidia (Utah, New Mexico, Texas, and Mexico), although belonging to the same major groups, differ at the species level from those on northern Laramidia (Montana, Wyoming, the Dakotas, and Canada). Lythronax and its tyrannosaurid relatives on southern Laramidia are more closely related to each other than the long snouted forms from northern Laramidia.
Dr. Joseph Sertich, a co-author of the study, stated that, “Lythronax may demonstrate that tyrannosaurs followed a pattern similar to what we see in other dinosaurs from this age, with different species living in the north and south at the same time.”
These patterns of dinosaur distribution across Laramidia lead the researchers to ask what might have caused the divisions between the north and south, given that an enterprising dinosaur could have walked from Alaska to Mexico if given enough time. Dr. Randall Irmis, a study co-author, explained that by analyzing the evolutionary relationships, geologic age, and geographic distribution of tyrannosaurid dinosaurs, the team determined that “Lythronax and other tyrannosaurids diversified between 95-80 million years ago, during a time when North America’s interior sea was at its widest extent. The incursion of the seaway onto large parts of low-lying Laramidia would have separated small areas of land from each other, allowing different species of dinosaurs to evolve in isolation on different parts of the landmass.” As the seaway gradually retreated after 80 million years ago, these differences in dinosaur species may have been reinforced by climate variations, differences in food sources (different prey and plants), and other factors. This hypothesis explains why the iconic Late Cretaceous dinosaurs of western North America are so different from those of the same age on other continents.
A Treasure Trove of Dinosaurs on the Lost Continent of Laramidia
Lythronax was discovered in Grand Staircase-Escalante National Monument (GSENM), which encompasses 1.9 million acres of high desert terrain in south-central Utah. This vast and rugged region, part of the National Landscape Conservation System administered by the Bureau of Land Management (BLM), was the last major area in the lower 48 states to be formally mapped by cartographers. Today GSENM is the largest national monument in the United States. Co-author Dr. Scott Sampson proclaimed that, “Grand Staircase-Escalante National Monument is the last great, largely unexplored dinosaur boneyard in the lower 48 states.”
During the past fourteen years, crews from the Natural History Museum of Utah, GSENM, the Denver Museum of Nature & Science, and several other partner institutions (for example, the Raymond Alf Museum of Paleontology and Utah Geological Survey) have unearthed a new assemblage of more than a dozen species dinosaurs in GSENM. In addition to Lythronax, the collection includes a variety of other plant-eating dinosaurs — among them duck-billed hadrosaurs, armored ankylosaurs, dome-headed pachycephalosaurs, and two other horned dinosaurs, Utahceratops and Kosmoceratops — together with carnivorous dinosaurs great and small, from “raptor-like” predators such as Talos, to another large tyrannosaur named Teratophoneus. Amongst the other fossil discoveries are fossil plants, insect traces, snails, clams, fishes, amphibians, lizards, turtles, crocodiles, and mammals. Together, this diverse bounty of fossils is offering one of the most comprehensive glimpses into a Mesozoic ecosystem. Remarkably, virtually all of the identifiable dinosaur remains found in GSENM belong to new species.
Dr. Philip Currie, another co-author, stated that, “Lythronax is a wonderful example of just how much more we have to learn about with world of dinosaurs. Many more exciting fossils await discovery in Grand Staircase-Escalante National Monument.”
Note : The above story is based on materials provided by University of Utah.
This shows thin slices of basalt with a diameter of just a fraction of a millimeter were subjected to high pressure in a diamond anvil cell. This sample has been molten and subsequently probed with X-rays three times. (Credit: Chrystèle Sanloup, University of Edinburgh)
Using the world’s most brilliant X-ray source, scientists have for the first time peered into molten magma at conditions of the deep Earth mantle. The analysis at DESY’s light source PETRA III revealed that molten basalt changes its structure when exposed to pressure of up to 60 gigapascals (GPa), corresponding to a depth of about 1400 kilometres below the surface. At such extreme conditions, the magma changes into a stiffer and denser form, the team around first author Chrystèle Sanloup from the University of Edinburgh reports in the scientific journal Nature.
The findings support the concept that the early Earth’s mantle harboured two magma oceans, separated by a crystalline layer. Today, these presumed oceans have crystallised, but molten magma still exists in local patches and maybe thin layers in the mantle.
“Silicate liquids like basaltic magma play a key role at all stages of deep Earth evolution, ranging from core and crust formation billions of years ago to volcanic activity today,” Sanloup emphasised. To investigate the behaviour of magma in the deep mantle, the researchers squeezed small pieces of basalt within a diamond anvil cell and applied up to roughly 600,000 times the standard atmospheric pressure. “But to investigate basaltic magma as it still exists in local patches within the Earth’s mantle, we first had to melt the samples,” explained co-author Zuzana Konôpková from DESY, who supported the experiments at the Extreme Conditions Beamline (ECB), P02 at PETRA III.
The team used two strong infrared lasers that each concentrated a power of up to 40 Watts onto an area just 20 micrometres (millionths of a metre) across — that is about 2000 times the power density at the surface of the sun. A clever alignment of the laser optics allowed the team to shoot the heating lasers right through the diamond anvils. With this unique setup, the basalt samples could be heated up to 3,000 degrees Celsius in just a few seconds, until they were completely molten. To avoid overheating of the diamond anvil cell which would have skewed the X-ray measurements, the heating laser was only switched on for a few seconds before and during the X-ray diffraction patterns were taken. Such short data collection times, crucial for this kind of melting experiments, are only possible thanks to the high X-ray brightness at the ECB. “For the first time, we could study structural changes in molten magma over such a wide range of pressure,” said Konôpková.
The powerful X-rays show that the so-called coordination number of silicon, the most abundant chemical element in magmas, in the melt increases from 4 to 6 under high pressure, meaning that the silicon ions rearrange into a configuration where each has six nearest oxygen neighbours instead of the usual four at ambient conditions. As a result, the basalt density increases from about 2.7 grams per cubic centimetre (g/ccm) at low pressure to almost 5 g/ccm at 60 GPa. “An important question was how this coordination number change happens in the molten state, and how that affects the physical and chemical properties,” explained Sanloup. “The results show that the coordination number changes from 4 to 6 gradually from 10 GPa to 35 GPa in magmas, and once completed, magmas are much stiffer, that is much less compressible.” In contrast, in mantle silicate crystals, the coordination number change occurs abruptly at 25 GPa, which defines the boundary between the upper and lower mantle.
This behaviour allows for the peculiar possibility of layered magma oceans in the early Earth’s interior. “At low pressure, magmas are much more compressible than their crystalline counterparts, while they are almost as stiff above 35 GPa,” explained Sanloup. “This implies that early in the history of the Earth, when it started crystallising, magmas may have been negatively buoyant at the bottom of both, upper and lower mantle, resulting in the existence of two magma oceans, separated by a crystalline layer, as has been proposed earlier by other scientists.”
At the high pressure of the lower Earth mantle, the magma becomes so dense that rocks do not sink into it anymore but float on top. This way a crystallised boundary between an upper and a basal magma ocean could have formed within the young Earth. The existence of two separate magma oceans had been postulated to reconcile geochronological estimates for the duration of the magma ocean era with cooling models for molten magma. While the geochronological estimates yield a duration of a few ten million years for the magma ocean era, cooling models show that a single magma ocean would have cooled much quicker, within just one million years. A crystalline layer would have isolated the lower magma ocean thermally and significantly delayed its cooling down. Today, there are still remnants of the basal magma ocean in the form of melt pockets detected atop the Earth’s core by seismology.
Note : The above story is based on materials provided by Deutsches Elektronen-Synchrotron DESY, via EurekAlert!, a service of AAAS.
The Cenozoic Era (also Cænozoic, Caenozoic or Cainozoic; meaning “new life”, from Greek καινός kainos “new”, and ζωή zoe “life”) is the current and most recent of the three Phanerozoic geological eras, following the Mesozoic Era and covering the period from 66 million years ago to the present.
The era began in the wake of the Cretaceous-Paleogene extinction event (K-Pg event) at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs (as well as many other terrestrial and marine flora and fauna) at the end of the Mesozoic. The Cenozoic is also known as the Age of Mammals, because the extinction of many groups allowed mammals to greatly diversify.
Early in the Cenozoic, following the K-Pg event, the planet was dominated by relatively small fauna, including small mammals, birds, reptiles, and amphibians. From a geological perspective, it did not take long for mammals and birds to greatly diversify in the absence of the large reptiles that had dominated during the Mesozoic. Some birds grew larger than the average human. This group became known as the “terror birds,” and were formidable predators. Mammals came to occupy almost every available niche (both marine and terrestrial), and some also grew very large, attaining sizes not seen in most of today’s mammals.
Climate-wise, the Earth had begun a drying and cooling trend, culminating in the glaciations of the Pleistocene Epoch, and partially offset by the Paleocene-Eocene Thermal Maximum. The continents also began looking roughly familiar at this time and moved into their current positions.
Subdivisions
The Cenozoic is divided into three periods: The Paleogene, Neogene, and Quaternary; and seven epochs: The Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene. The Quaternary Period was officially recognized by the International Commission on Stratigraphy in June 2009, and the former Tertiary Period was officially disused in 2004. The common use of epochs during the Cenozoic helps paleontologists better organize and group the many significant events that occurred during this comparatively short interval of time. There is also more detailed knowledge of this era than any other because of the relatively young strata associated with it.
Tectonics
Geologically, the Cenozoic is the era when the continents moved into their current positions. Australia-New Guinea, having split from Pangea during the early Cretaceous, drifted north and, eventually, collided with South-east Asia; Antarctica moved into its current position over the South Pole; the Atlantic Ocean widened and, later in the era, South America became attached to North America.
India collided with Asia 55 to 45 million years ago; Arabia collided with Eurasia, closing the Tethys ocean, around 35 million years ago.
Stratigraphy
**The concepts of Tertiary and Quaternary have an interesting history. In the 1760s and 1770s a geologist named Giovanni Arduino was studying the rocks and minerals in Tuscany. He classified mountains according to the type of rocks that he found in them. Unfossiliferous schists, granites, and basalts (all volcanic rocks) that formed the cores of large mountains he called Primitive. Fossil-rich rocks of limestone and clay that were found on the flanks of mountains over the Primitive rocks were called Secondary. Finally, there were another group of fossiliferous rocks of limestones and sandstones lying over the Secondary rocks and forming the foothills of the mountains that Anduino called Tertiary. So at first, Tertiary referred to a certain type of rock found in the area of Tuscany. But later, geologists used the fossils found in the Tertiary rocks there to recognize rocks of the same age elsewhere. Rocks with the same species of fossils were the same age.
Extensive Tertiary age rocks were recognized in the Paris Basin, which is the area around Paris, France. In the 1820s and 1830s Charles Lyell, a noted English geologist who had a great influence on Charles Darwin, subdivided the Tertiary rocks of the Paris Basin on their fossils. Lyell came up with an ingenious idea. He noticed that the rocks at the top of the section had a very high percentage of fossils of living mollusc species. Those at the bottom of the section had very few living forms. He deduced that this difference was because of the extinction of older forms and the evolution of living forms during the time that the rocks were being deposited. He divided the Tertiary rocks into three sub-ages: the Pliocene, the Miocene, and the Eocene. 90% of the fossil molluscs in Pliocene rocks were living today. In the Miocene rocks, only 18% of the molluscs were of living species, and in Eocene rocks, only 9.5%.
These subdivisions of the Tertiary have been correlated around the world using the fossil species in them. Rocks with the same species as Lyell’s Eocene, are considered to be the same age as those in the Paris Basin. The same goes for the other subdivisions. Some time later it was noted that in areas other than the Paris Basin, there were rocks that seemed to be from time periods that were not represented in Lyell’s sequence. This was because during those periods there had been no deposition in what would later be the Paris Basin. These two periods, later designated Oligocene and Paleocene, were inserted into the Tertiary in their proper places.
Climate
The Paleocene–Eocene Thermal Maximum of 55.8 million years ago was a significant global warming event. However, since the Azolla event of 49 million years ago, the Cenozoic Era has been a period of long-term cooling. After the tectonic creation of Drake Passage, when South America fully detached from Antarctica during the Oligocene, the climate cooled significantly due to the advent of the Antarctic Circumpolar Current which brought cool deep Antarctic water to the surface. The cooling trend continued in the Miocene, with relatively short warmer periods. When South America became attached to North America creating the Isthmus of Panama, the Arctic region cooled due to the strengthening of the Humboldt and Gulf Stream currents, eventually leading to the glaciations of the Quaternary ice age, the current interglacial of which is the Holocene Epoch.
Life
During the Cenozoic, mammals proliferated from a few small, simple, generalized forms into a diverse collection of terrestrial, marine, and flying animals, giving this period its other name, the Age of Mammals, despite the fact that birds still outnumbered mammals two to one. The Cenozoic is just as much the age of savannas, the age of co-dependent flowering plants and insects, and the age of birds. Grass also played a very important role in this era, shaping the evolution of the birds and mammals that fed on it. One group that diversified significantly in the Cenozoic as well were the snakes. Evolving in the Cenozoic, the variety of snakes increased tremendously, resulting in many colubrids, following the evolution of their current primary prey source, the rodents.
In the earlier part of the Cenozoic, the world was dominated by the gastornid birds, terrestrial crocodiles like Pristichampsus, and a handful of primitive large mammal groups like uintatheres, mesonychids, and pantodonts. But as the forests began to recede and the climate began to cool, other mammals took over. The Cenozoic is full of mammals both strange and familiar, including chalicotheres, creodonts, whales, primates, entelodonts, saber-toothed cats, mastodons and mammoths, three-toed horses, giant rhinoceros like Indricotherium, and brontotheres.
Note : The above story is based on materials provided by Wikipedia
** Stratigraphy story is based on materials provided by University of California Museum of Paleontology
This shows Antarctic locations (in bright blue) where 1.5 million years old ice could exist. The figure is modified from Van Liefferinge and Pattyn (Climate of the Past, 2013). Credit: Van Liefferinge and Pattyn
How far into the past can ice-core records go? Scientists have now identified regions in Antarctica they say could store information about Earth’s climate and greenhouse gases extending as far back as 1.5 million years, almost twice as old as the oldest ice core drilled to date. The results are published today in Climate of the Past, an open access journal of the European Geosciences Union (EGU).
By studying the past climate, scientists can understand better how temperature responds to changes in greenhouse-gas concentrations in the atmosphere. This, in turn, allows them to make better predictions about how climate will change in the future.
“Ice cores contain little air bubbles and, thus, represent the only direct archive of the composition of the past atmosphere,” says Hubertus Fischer, an experimental climate physics professor at the University of Bern in Switzerland and lead author of the study. A 3.2-km-long ice core drilled almost a decade ago at Dome Concordia (Dome C) in Antarctica revealed 800,000 years of climate history, showing that greenhouse gases and temperature have mostly moved in lockstep. Now, an international team of scientists wants to know what happened before that.
At the root of their quest is a climate transition that marine-sediment studies reveal happened some 1.2 million years to 900,000 years ago. “The Mid Pleistocene Transition is a most important and enigmatic time interval in the more recent climate history of our planet,” says Fischer. The Earth’s climate naturally varies between times of warming and periods of extreme cooling (ice ages) over thousands of years. Before the transition, the period of variation was about 41 thousand years while afterwards it became 100 thousand years. “The reason for this change is not known.”
Climate scientists suspect greenhouse gases played a role in forcing this transition, but they need to drill into the ice to confirm their suspicions. “The information on greenhouse-gas concentrations at that time can only be gained from an Antarctic ice core covering the last 1.5 million years. Such an ice core does not exist yet, but ice of that age should be in principle hidden in the Antarctic ice sheet.”
As snow falls and settles on the surface of an ice sheet, it is compacted by the weight of new snow falling on top of it and is transformed into solid glacier ice over thousands of years. The weight of the upper layers of the ice sheet causes the deep ice to spread, causing the annual ice layers to become thinner and thinner with depth. This produces very old ice at depths close to the bedrock.
However, drilling deeper to collect a longer ice core does not necessarily mean finding a core that extends further into the past. “If the ice thickness is too high the old ice at the bottom is getting so warm by geothermal heating that it is melted away,” Fischer explains. “This is what happens at Dome C and limits its age to 800,000 years.”
To complicate matters further, horizontal movements of the ice above the bedrock can disturb the bottommost ice, causing its annual layers to mix up.
“To constrain the possible locations where such 1.5 million-year old – and in terms of its layering undisturbed – ice could be found in Antarctica, we compiled the available data on climate and ice conditions in the Antarctic and used a simple ice and heat flow model to locate larger areas where such old ice may exist,” explains co-author Eric Wolff of the British Antarctic Survey, now at the University of Cambridge.
The team concluded that 1.5 million-year old ice should still exist at the bottom of East Antarctica in regions close to the major Domes, the highest points on the ice sheet, and near the South Pole, as described in the new Climate of the Past study. These results confirm those of another study, also recently published in Climate of the Past.
Crucially, they also found that an ice core extending that far into the past should be between 2.4 and 3-km long, shorter than the 800,000-year-old core drilled in the previous expedition.
The next step is to survey the identified drill sites to measure the ice thickness and temperature at the bottom of the ice sheet before selecting a final drill location.
“A deep drilling project in Antarctica could commence within the next 3-5 years,” Fischer states. “This time would also be needed to plan the drilling logistically and create the funding for such an exciting large-scale international research project, which would cost around 50 million Euros.”
Note : The above story is based on materials provided by European Geosciences Union
