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Bees Underwent Massive Extinctions When Dinosaurs Did

A small carpenter bee. (Credit: Sandra Rehan)

For the first time ever, scientists have documented a widespread extinction of bees that occurred 65 million years ago, concurrent with the massive event that wiped out land dinosaurs and many flowering plants. Their findings, published this week in the journal PLOS ONE, could shed light on the current decline in bee species.

Lead author Sandra Rehan, an assistant professor of biological sciences at UNH, worked with colleagues Michael Schwarz at Australia’s Flinders University and Remko Leys at the South Australia Museum to model a mass extinction in bee group Xylocopinae, or carpenter bees, at the end of the Cretaceous and beginning of the Paleogene eras, known as the K-T boundary.

Previous studies have suggested a widespread extinction among flowering plants at the K-T boundary, and it’s long been assumed that the bees who depended upon those plants would have met the same fate. Yet unlike the dinosaurs, “there is a relatively poor fossil record of bees,” says Rehan, making the confirmation of such an extinction difficult.

Rehan and colleagues overcame the lack of fossil evidence for bees with a technique called molecular phylogenetics. Analyzing DNA sequences of four “tribes” of 230 species of carpenter bees from every continent except Antarctica for insight into evolutionary relationships, the researchers began to see patterns consistent with a mass extinction. Combining fossil records with the DNA analysis, the researchers could introduce time into the equation, learning not only how the bees are related but also how old they are.

“The data told us something major was happening in four different groups of bees at the same time,” says Rehan, of UNH’s College of Life Sciences and Agriculture. “And it happened to be the same time as the dinosaurs went extinct.”

While much of Rehan’s work involves behavioral observation of bees native to the northeast of North America, this research taps the computer-heavy bioinformatics side of her research, assembling genomic data to elucidate similarities and differences among the various species over time. Marrying observations from the field with genomic data, she says, paints a fuller picture of these bees’ behaviors over time.

“If you could tell their whole story, maybe people would care more about protecting them,” she says. Indeed, the findings of this study have important implications for today’s concern about the loss in diversity of bees, a pivotal species for agriculture and biodiversity.

“Understanding extinctions and the effects of declines in the past can help us understand the pollinator decline and the global crisis in pollinators today,” Rehan says.

The article, “First evidence for a massive extinction event affecting bees close to the K-T boundary,” was published in the Oct. 23, 2013 edition of PLOS ONE. Funding for the research was provided by Endeavour Research Fellowships (Rehan) and Australian Research Council Discovery Grants (Schwarz).

The University of New Hampshire, founded in 1866, is a world-class public research university with the feel of a New England liberal arts college. A land, sea, and space-grant university, UNH is the state’s flagship public institution, enrolling 12,300 undergraduate and 2,200 graduate students.

Note : The above story is based on materials provided by University of New Hampshire.

Reading Ancient Climate from Plankton Shells

The intricate structure of plankton shells provides new opportunities to chart complex changes in climate. (Credit: Oscar Branson, University of Cambridge)
The intricate structure of plankton shells provides new opportunities to chart complex changes in climate. (Credit: Oscar Branson, University of Cambridge)

Climate changes from millions of years ago are recorded at daily rate in ancient sea shells, new research shows.

A huge X-ray microscope has revealed growth bands in plankton shells that show how shell chemistry records the sea temperature.

The results could allow scientists to chart short timescale changes in ocean temperatures hundreds of millions of years ago.

Plankton shells show features like tree rings, recording historical climate.

It’s important to understand current climate change in the light of how climate has varied in the geological past. One way to do this, for the last few thousand years, is to analyse ice from the poles. The planet’s temperature and atmosphere are recorded by bubbles of ancient air trapped in polar ice cores. The oldest Antarctic ice core records date back to around 800,000 years ago.

Results just published in the journal Earth and Planetary Sciences Letters reveal how ancient climate change, pushing back hundreds of millions of years ago into deep time, is recorded by the shells of oceanic plankton.

As microbial plankton grow in ocean waters, their shells, made of the mineral calcite, trap trace amounts of chemical impurities, maybe only a few atoms in a million getting replaced by impurity atoms. Scientists have noticed that plankton growing in warmer waters contain more impurities, but it has not been clear how and why this “proxy” for temperature works.

When the plankton die, they fall to the muddy ocean floor, and can be recovered today from that muddy ocean floor sediments, which preserve the shells as they are buried. The amount of impurity, measured in fossil plankton shells, provides a record of past ocean temperature, dating back more than 100 million years ago.

Now, researchers from the Department of Earth Sciences at the University of Cambridge have measured traces of magnesium in the shells of plankton using an X-ray microscope in Berkeley, California, at the “Advanced Light Source” synchrotron — a huge particle accelerator that generates X-rays to study matter in minuscule detail.

The powerful X-ray microscope has revealed narrow nanoscale bands in the plankton shell where the amount of magnesium is very slightly higher, at length scales as small as one hundredth that of a human hair. They are growth bands, rather like tree rings, but in plankton the bands occur daily or so, rather than yearly.

“These growth bands in plankton show the day by day variations in magnesium in the shell at a 30 nanometre length scale. For slow-growing plankton it opens the way to seeing seasonal variations in ocean temperatures or plankton growth in samples dating back tens to hundreds of millions of years,” says Professor Simon Redfern, one of the experimenters on the project.

“Our X-ray data show that the trace magnesium sits inside the crystalline mineral structure of the plankton shell. That’s important because it validates previous assumptions about using magnesium contents as a measure of past ocean temperature.”

The chemical environment of the trace elements in the plankton shell, revealed in the new measurements, shows that the magnesium sits in calcite crystal replacing calcium, rather than in microbial membranes in their impurities in the shell. This helps explain why temperature affects the chemistry of plankton shells — warmer waters favour increased magnesium in calcite.

The group are now using the UK’s “Diamond” synchrotron X-ray facility to measure how plankton shells grow and whether they change at all in the ocean floor sediments. Their latest results could allow scientists to establish climate variability in Earth’s far distant past, as well as providing new routes to measure ocean acidification and salinity in past oceans.

Note : The above story is based on materials provided by University of Cambridge, via EurekAlert!, a service of AAAS. The original story is licensed under a Creative Commons Licence.

Study shows unprecedented warmth in Arctic

University of Colorado Boulder Professor Gifford Miller is shown here collecting dead plant samples from the edge of a Baffin Island ice cap. (Credit: University of Colorado)

The heat is on, at least in the Arctic. Average summer temperatures in the Eastern Canadian Arctic during the last 100 years are higher now than during any century in the past 44,000 years and perhaps as long ago as 120,000 years, says a new University of Colorado Boulder study.

 

>The study is the first direct evidence the present warmth in the Eastern Canadian Arctic exceeds the peak warmth there in the Early Holocene, when the amount of the sun’s energy reaching the Northern Hemisphere in summer was roughly 9 percent greater than today, said CU-Boulder geological sciences Professor Gifford Miller, study leader. The Holocene is a geological epoch that began after Earth’s last glacial period ended roughly 11,700 years ago and which continues today.

Miller and his colleagues used dead moss clumps emerging from receding ice caps on Baffin Island as tiny clocks. At four different ice caps, radiocarbon dates show the mosses had not been exposed to the elements since at least 44,000 to 51,000 years ago.

Since radiocarbon dating is only accurate to about 50,000 years and because Earth’s geological record shows it was in a glaciation stage prior to that time, the indications are that Canadian Arctic temperatures today have not been matched or exceeded for roughly 120,000 years, Miller said.

“The key piece here is just how unprecedented the warming of Arctic Canada is,” said Miller, also a fellow at CU-Boulder’s Institute of Arctic and Alpine Research. “This study really says the warming we are seeing is outside any kind of known natural variability, and it has to be due to increased greenhouse gases in the atmosphere.”

A paper on the subject appeared online Oct. 21 in Geophysical Research Letters, a journal published by the American Geophysical Union. Co-authors include CU-Boulder Senior Research Associate Scott Lehman, former CU-Boulder doctoral student and now Prescott College Professor Kurt Refsnider, University of California Irvine researcher John Southon and University of Wisconsin, Madison Research Associate Yafang Zhong. The National Science Foundation provided the primary funding for the study.

Miller and his colleagues compiled the age distribution of 145 radiocarbon-dated plants in the highlands of Baffin Island that were exposed by ice recession during the year they were collected by the researchers. All samples collected were within 1 meter of the ice caps, which are generally receding by 2 to 3 meters a year. “The oldest radiocarbon dates were a total shock to me,” said Miller.

Located just east of Greenland, the 196,000-square-mile Baffin Island is the fifth largest island in the world. Most of it lies above the Arctic Circle. Many of the ice caps on the highlands of Baffin Island rest on relatively flat terrain, usually frozen to their beds. “Where the ice is cold and thin, it doesn’t flow, so the ancient landscape on which they formed is preserved pretty much intact,” said Miller.

To reconstruct the past climate of Baffin Island beyond the limit of radiocarbon dating, Miller and his team used data from ice cores previously retrieved by international teams from the nearby Greenland Ice Sheet.

The ice cores showed that the youngest time interval from which summer temperatures in the Arctic were plausibly as warm as today is about 120,000 years ago, near the end of the last interglacial period. “We suggest this is the most likely age of these samples,” said Miller.

The new study also showed summer temperatures cooled in the Canadian Arctic by about 5 degrees Fahrenheit from roughly 5,000 years ago to about 100 years ago — a period that included the Little Ice Age from 1275 to about 1900.

“Although the Arctic has been warming since about 1900, the most significant warming in the Baffin Island region didn’t really start until the 1970s,” said Miller. “And it is really in the past 20 years that the warming signal from that region has been just stunning. All of Baffin Island is melting, and we expect all of the ice caps to eventually disappear, even if there is no additional warming.”

Temperatures across the Arctic have been rising substantially in recent decades as a result of the buildup of greenhouse gases in Earth’s atmosphere. Studies by CU-Boulder researchers in Greenland indicate temperatures on the ice sheet have climbed 7 degrees Fahrenheit since 1991.

A 2012 study by Miller and colleagues using radiocarbon-dated mosses that emerged from under the Baffin Island ice caps and sediment cores from Iceland suggested that the trigger for the Little Ice Age was likely a combination of exploding tropical volcanoes — which ejected tiny aerosols that reflected sunlight back into space — and a decrease in solar radiation.

Note : The above story is based on materials provided by University of Colorado at Boulder.

Archean Eon

The geological clock: a projection of Earth’s 4,5 Ga history on a clock (“MA” = a million years (Megayear) ago; “GA” = a billion years (Gigayear) ago) Author: Woudloper Derivative work: Hardwigg Wikipedia

The Archean  is a geologic eon before the Proterozoic Eon, before 2.5 Ga (billion years), or 2,500 million years ago.

Classification issues

Instead of being based on stratigraphy as all other geological ages are, the beginning of the Archean eon is defined chronometrically. The lower boundary (starting point) of 4 billion years is officially recognized by the International Commission on Stratigraphy.

The Archean customarily starts at 4 Ga—at the end of the Hadean Eon. In older literature, the Hadean is included as part of the Archean. The name comes from the ancient Greek Αρχή (Arkhē), meaning “beginning, origin”.

Earth

The Archean is one of the four principal eons of Earth history. When the Archean began, the Earth’s heat flow was nearly three times as high as it is today, and it was still twice the current level at the transition from the Archean to the Proterozoic (2,500 Ma). The extra heat was the result of a mix of remnant heat from planetary accretion, heat from the formation of the Earth’s core, and heat produced by radioactive elements.

Most surviving Archean rocks are metamorphic or igneous. Volcanic activity was considerably higher than today, with numerous lava eruptions, including unusual types such as komatiite. Granitic rocks predominate throughout the crystalline remnants of the surviving Archean crust. Examples include great melt sheets and voluminous plutonic masses of granite, diorite, layered intrusions, anorthosites and monzonites known as sanukitoids.

The Earth of the early Archean may have supported a tectonic regime unlike that of the present. Some scientists argue that, because the Earth was much hotter, tectonic activity was more vigorous than it is today, resulting in a much faster rate of recycling of crustal material. This may have prevented cratonisation and continent formation until the mantle cooled and convection slowed down. Others argue that the oceanic lithosphere was too buoyant to subduct, and that the rarity of Archean rocks is a function of erosion by subsequent tectonic events. The question of whether plate tectonic activity existed in the Archean is an active area of modern research.

There are two schools of thought concerning the amount of continental crust that was present in the Archean. One school maintains that no large continents existed until late in the Archean: small protocontinents were the norm, prevented from coalescing into larger units by the high rate of geologic activity. The other school follows the teaching of Richard Armstrong, who argued that the continents grew to their present volume in the first 500 million years of Earth history and have maintained a near-constant ever since: throughout most of Earth history, recycling of continental material crust back to the mantle in subduction or collision zones balances crustal growth.

Opinion is also divided about the mechanism of continental crustal growth. Those scientists who doubt that plate tectonics operated in the Archean argue that the felsic protocontinents formed at hotspots rather than subduction zones. Through a process called “sagduction”, which refers to partial melting in downward-directed diapirs, a variety of mafic magmas produce intermediate and felsic rocks. Others accept that granite formation in island arcs and convergent margins was part of the plate tectonic process, which has operated since at least the start of the Archean.

An explanation for the general lack of Hadean rocks (older than 3800 Ma) is the efficiency of the processes that either cycled these rocks back into the mantle or effaced any isotopic record of their antiquity. All rocks in the continental crust are subject to metamorphism, partial melting and tectonic erosion during multiple orogenic events and the chance of survival at the surface decreases with increasing age. In addition, a period of intense meteorite bombardment in the period 4.0-3.8 Ga pulverized all rocks at the Earth’s surface during the period. Some think that the similar age of the oldest surviving rocks and the “late heavy bombardment” is not coincidental.

Palaeoenvironment

The Archean atmosphere is thought to have nearly lacked free oxygen. Astronomers think that the sun had about 70–75% of the present luminosity, yet temperatures appear to have been near modern levels even within 500 Ma of Earth’s formation, which is puzzling (the faint young sun paradox). The presence of liquid water is evidenced by certain highly deformed gneisses produced by metamorphism of sedimentary protoliths. The equable temperatures may reflect the presence of larger amounts of greenhouse gases than later in the Earth’s history. Alternatively, Earth’s albedo may have been lower at the time, due to less land area and cloud cover.

By the end of the Archaean c. 2500 Ma (million years ago), plate tectonic activity may have been similar to that of the modern Earth. There are well-preserved sedimentary basins, and evidence of volcanic arcs, intracontinental rifts, continent-continent collisions and widespread globe-spanning orogenic events suggesting the assembly and destruction of one and perhaps several supercontinents. Liquid water was prevalent, and deep oceanic basins are known to have existed by the presence of banded iron formations, chert beds, chemical sediments and pillow basalts.

Geology

Although a few mineral grains are known that are Hadean, the oldest rock formations exposed on the surface of the Earth are Archean or slightly older. Archean rocks are known from Greenland, the Canadian Shield, the Baltic Shield, Scotland, India, Brazil, western Australia, and southern Africa. Although the first continents formed during this eon, rock of this age makes up only 7% of the world’s current cratons; even allowing for erosion and destruction of past formations, evidence suggests that continental crust equivalent to only 5-40% of the present amount formed during the Archean.

In contrast to Proterozoic rocks, Archean rocks are often heavily metamorphized deep-water sediments, such as graywackes, mudstones, volcanic sediments, and banded iron formations. Carbonate rocks are rare, indicating that the oceans were more acidic due to dissolved carbon dioxide than during the Proterozoic.Greenstone belts are typical Archean formations, consisting of alternating units of metamorphosed mafic igneous and sedimentary rocks. The meta-igneous rocks were derived from volcanic island arcs, while the metasediments represent deep-sea sediments eroded from the neighboring island arcs and deposited in a forearc basin. Greenstone belts represent sutures between protocontinents.

Life

Fossils of cyanobacterial mats (stromatolites, which were instrumental in creating the free oxygen in the atmosphere ) are found throughout the Archean, becoming especially common late in the eon, while a few probable bacterial fossils are known from chert beds. In addition to the domain Bacteria (once known as Eubacteria), microfossils of the domain Archaea have also been identified.

Life was probably present throughout the Archean, but may have been limited to simple non-nucleated single-celled organisms, called Prokaryota (formerly known as Monera). There are no known eukaryotic fossils, though they might have evolved during the Archean without leaving any fossils. No fossil evidence has been discovered for ultramicroscopic intracellular replicators such as viruses.

Note : The above story is based on materials provided by Wikipedia

High School Student Discovers Skeleton of Baby Dinosaur

This is the skeleton of the baby Parasaurolophus nicknamed “Joe.” Credit: Raymond M. Alf Museum of Paleontology

Claremont, CA – A chance find by a high school student led to the youngest, smallest and most complete fossil skeleton yet known from the iconic tube-crested dinosaur Parasaurolophus. The discovery, announced today by the Raymond M. Alf Museum of Paleontology at The Webb Schools, shows that the prehistoric plant-eater sprouted its strange headgear before it celebrated its first birthday. Three-dimensional scans of nearly the entire fossil are freely available online, making this the most digitally-accessible dinosaur to date.

The fossil skeleton was discovered in 2009 by high school student Kevin Terris, within Grand Staircase-Escalante National Monument in southern Utah. Incredibly, the specimen was missed by two professional paleontologists, who walked within several feet of the exposed bones days prior to the discovery. “At first I was interested in seeing what the initial piece of bone sticking out of the rock was,” commented Terris. “When we exposed the skull, I was ecstatic!” Excavation and subsequent cleaning of the fossil, nicknamed “Joe” after a long-time supporter of the Alf Museum whose family funded preparation of the fossil, revealed nearly the entire skeleton of a baby dinosaur measuring only six feet long when it died.

Detailed study of the skeleton of “Joe” identified it as the most complete specimen yet known for Parasaurolophus (pronounced PAIR-uh-SORE-AH-luf-us), a duck-billed (hadrosaurid) dinosaur that lived throughout western North America around 75 million years ago. The herbivore is notable for a long and hollow bony tube on the top of its skull, which scientists speculate was used like a trumpet to blast sound for communication, as well as a billboard for visual display. Although partial skulls and skeletons of full-grown Parasaurolophus have been known for over 90 years, scientists previously knew little about how Parasaurolophus grew up.

Intriguingly, the new fossil shows that baby Parasaurolophus had a low bump on top of its head, which only later morphed into the curved tube of adults. “Our baby Parasaurolophus is barely one-quarter of adult size, but it had already started growing its crest,” stated lead project scientist Andrew Farke, who is Augustyn Family Curator at the Raymond M. Alf Museum of Paleontology. “This is surprising, because related dinosaurs didn’t sprout their ornamentation until they were at least half-grown. Parasaurolophus had to get an early start in order to form its unique headgear.”

A sample of bone from the leg helped estimate the animal’s age at death. “Dinosaurs have yearly growth rings in their bone tissue, like trees. But we didn’t see even one ring. That means it grew to a quarter of adult size in less than a year,” commented co-author Sarah Werning of Stony Brook University. Although “Joe” was only six feet long and a year old, it would have grown to 25 feet in length as an adult.

The fossil skeleton has yielded a world of previously unknown information about Parasaurolophus and its relatives. Medical scans documented the internal anatomy of the animal’s skull, allowing a reconstruction of its vocal capabilities. “If adult Parasaurolophus had ‘woofers,’ the babies had ‘tweeters.’ The short and small crest of baby ‘Joe’ shows that it may have had a much higher pitch to its call than did adults,” stated Andrew Farke. “Along with the visual differences, this might have helped animals living in the same area to figure out who was the big boss.”

Because of the broad importance of the fossil, researchers have made 3D digital scans of the entire fossil freely available on-line (links via http://www.dinosaurjoe.com). Although portions of other dinosaur fossils have been scanned and distributed in this way before, this the first time that virtually an entire skeleton has been posted. This will allow scientists and the public alike unparalleled access to this fossil.

This image shows a comparison of the size of the baby Parasaurolophus (green) to adult Parasaurolophus, as well as an adult and baby human. Credit: Scott Hartman, Matt Martyniuk, and Raymond M. Alf Museum of Paleontology

The study describing the new fossil was published today in the open access scientific journal PeerJ (meaning that anyone can read and download the article for free, and without restrictions). Additionally, the specimen is now on exhibit at the Raymond M. Alf Museum of Paleontology in Claremont, California. Researchers who co-authored the study include Andrew Farke (Raymond M. Alf Museum of Paleontology, Claremont, California), Sarah Werning (University of California Museum of Paleontology, Berkeley, and Stony Brook University, New York), and high school students Derek Chok, Annisa Herrero, and Brandon Scolieri (The Webb Schools, Claremont, California). The fossil was collected under a permit from Grand Staircase-Escalante National Monument and the Bureau of Land Management, Utah.

Video :

Note : The above story is based on materials provided by Raymond M. Alf Museum of Paleontology, via EurekAlert!, a service of AAAS. 

Quake-triggered landslides pose significant hazard for Seattle, new study details potential damage

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Locations of each zoom-in are shown on the map of Seattle at right. A) Coastal bluffs in the northern part of Seattle are most affected when soils are saturated. B) There are several areas along the I-5 corridor that are highly susceptible to landsliding for all soil saturation levels, such as the area shown here near the access point to the West Seattle bridge. C) The hillsides in West Seattle along the Duwamish valley are at risk of seismically induced landsliding, such as the area shown here. There are industrial as well as 59 residential buildings that could be affected by runout from landsliding in these areas. D) The coastal bluffs along Puget Sound in West Seattle on the hanging wall of the fault, such as the area shown here, are the most highly susceptible areas to landsliding in the city; numerous residential structures are at risk from both potential landslide source areas and runout.Credit: Allstadt/BSSA

SAN FRANCISCO — SAN FRANCISCO — A new study suggests the next big quake on the Seattle fault may cause devastating damage from landslides, greater than previously thought and beyond the areas currently defined as prone to landslides. Published online Oct. 22 by the Bulletin of the Seismological Society of America (BSSA), the research offers a framework for simulating hundreds of earthquake scenarios for the Seattle area.

“A major quake along the Seattle fault is among the worst case scenarios for the area since the fault runs just south of downtown. Our study shows the need for dedicated studies on seismically induced landsliding” said co-author Kate Allstadt, doctoral student at University of Washington.

Seattle is prone to strong shaking as it sits atop the Seattle Basin – a deep sedimentary basin that amplifies ground motion and generates strong seismic waves that tend to increase the duration of the shaking. The broader region is vulnerable to earthquakes from multiple sources, including deep earthquakes within the subducted Juan de Fuca plate, offshore megathrust earthquakes on Cascadia subduction zone and the shallow crustal earthquakes within the North American Plate.

For Seattle, a shallow crustal earthquake close to the city would be most damaging. The last major quake along the Seattle fault was in 900 AD, long before the city was established, though native people lived in the area. The earthquake triggered giant landslides along Lake Washington, causing entire blocks of forest to slide into the lake.

“There’s a kind of haunting precedence that tells us that we should pay attention to a large earthquake on this fault because it happened in the past,” said Allstadt, who also serves as duty seismologist for the Pacific Northwest Seismic Network. John Vidale of University of Washington and Art Frankel of the U.S. Geological Survey (USGS) are co-authors of the study, which was funded by the USGS.

While landslides triggered by earthquakes have caused damage and casualties worldwide, they have not often been the subject of extensive quantitative study or fully incorporated into seismic hazard assessments, say authors of this study that looks at just one scenario among potentially hundreds for a major earthquake in the Seattle area.

Dividing the area into a grid of 210-meter cells, they simulated ground motion for a magnitude 7 Seattle fault earthquake and then further subdivided into 5-meter cells, applying anticipated amplification of shaking due to the shallow soil layers. This refined framework yielded some surprises.

“One-third of the landslides triggered by our simulation were outside of the areas designated by the city as prone to landsliding,” said Allstadt. “A lot of people assume that all landslides occur in the same areas, but those triggered by rainfall or human behavior have a different triggering mechanism than landslides caused by earthquakes so we need dedicated studies.”

While soil saturation — whether the soil is dry or saturated with water – is the most important factor when analyzing the potential impact of landslides, the details of ground motion rank second. The amplification of ground shaking, directivity of seismic energy and geological features that may affect ground motion are very important to the outcome of ground failure, say authors.

The authors stress that this is just one randomized scenario study of many potential earthquake scenarios that could strike the city. While the results do not delineate the exact areas that will be affected in a future earthquake, they do illustrate the extent of landsliding to expect for a similar event.

The study suggests the southern half of the city and the coastal bluffs, many of which are developed, would be hardest hit. Depending upon the water saturation level of the soil at the time of the earthquake, several hundred to thousands of buildings could be affected citywide. For dry soil conditions, there are more than 1000 buildings that are within all hazard zones, 400 of those in the two highest hazard designation zones. The analysis suggests landslides could also affect some inland slopes, threatening key transit routes and impeding recovery efforts. For saturated soil conditions, it is an order of magnitude worse, with 8000 buildings within all hazard zones, 5000 of those within the two highest hazard zones. These numbers only reflect the number of buildings in high-risk areas, not the number of buildings that would necessarily suffer damage.

“The extra time we took to include the refined ground motion detail was worth it. It made a significant difference to our understanding of the potential damage to Seattle from seismically triggered landslides,” said Allstadt, who would like to use the new framework to run many more scenarios to prepare for future earthquakes in Seattle.

Note : The above story is based on materials provided by Seismological Society of America, via EurekAlert!, a service of AAAS.

Hadean Eon

The geological clock: a projection of Earth’s 4,5 Ga history on a clock Author: Woudloper Derivative work: Hardwigg Wikipedia

The Hadean  is the first geologic eon of Earth and lies before the Archean. It began with the formation of the Earth about 4600 million years ago and ended as defined by the ICS 4,000 million years ago.

The name “Hadean” comes from Hades, the ancient Greek god of the underworld due to the “hellish” conditions on Earth at the time: the planet had just formed and was still very hot due to high volcanism, a partially molten surface and frequent collisions with other Solar System bodies.

The geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-known rocks on Earth. W. Brian Harland later coined an almost synonymous term: the “Priscoan period”. Other, older texts simply refer to the eon as the Pre-Archean.

Table of Contents

Subdivisions

Since few geological traces of this eon remain on Earth there is no official subdivision. However, the Lunar geologic timescale embraces several major divisions relating to the Hadean and so these are sometimes used in a somewhat informal sense to refer to the same periods of time on Earth.

The Lunar divisions are:

  •     Pre-Nectarian, from the formation of the Moon’s crust up to about 3,920 million years ago
  •     Nectarian ranging up to about 3,850 million years ago, in a time when the Late Heavy Bombardment, according to that theory, was in a stage of decline.
There is a recently proposed alternative scale that includes the addition of the Chaotian and Prenephelean Eons preceding the Hadean, and divides the Hadean into three eras with two periods each. The Paleohadean era consists of the Hephaestean (4.5-4.4 Ga) and the Jacobian periods (4.4-4.3 Ga). The Mesohadean is divided into the Canadian (4.3-4.2 Ga) and the Procrustean periods (4.2-4.1 Ga). The Neohadean is divided into the Acastan (4.1-4.0 Ga) and the Promethean periods (4.0-3.9 Ga).

Hadean rocks

A sizeable quantity of water would have been in the material that formed the Earth. Water molecules would have escaped Earth’s gravity more easily when it was less massive during its formation. Hydrogen and helium are expected to continually escape (even to the present day) due to atmospheric escape.

Part of the ancient planet is theorized to have been disrupted by the impact that created the Moon, which should have caused melting of one or two large areas. Present composition does not match complete melting and it is hard to completely melt and mix huge rock masses. However, a fair fraction of material should have been vaporized by this impact, creating a rock vapor atmosphere around the young planet. The rock vapor would have condensed within two thousand years, leaving behind hot volatiles which probably resulted in a heavy CO2 atmosphere with hydrogen and water vapor. Liquid water oceans existed despite the surface temperature of 230 °C (446 °F) because of the atmospheric pressure of the heavy CO2 atmosphere. As cooling continued, subduction and dissolving in ocean water removed most CO2 from the atmosphere but levels oscillated wildly as new surface and mantle cycles appeared.

Study of zircons has found that liquid water must have existed as long ago as 4,400 million years ago, very soon after the formation of the Earth. This requires the presence of an atmosphere. The Cool Early Earth theory covers a range from about 4,400 to 4,000 million years ago.

A September 2008 study of zircons found that Australian Hadean rock holds minerals that point to the existence of plate tectonics as early as 4,000 million years ago. If this is true, the time when Earth finished its transition from having a hot, molten surface and atmosphere full of carbon dioxide, to being very much like it is today, can be roughly dated to about 4.0 billion years ago. The action of plate tectonics and the oceans traps vast amounts of carbon dioxide, thereby eliminating the greenhouse effect and leading to a much cooler surface temperature and the formation of solid rock, and possibly even life.

Note : The above story is based on materials provided by Wikipedia

Deepwater Mining in Norway

The islands along the Mid-Atlantic Ridge, such as Iceland and Jan Mayen, were created from red-hot lava escaping from the Earth's crust. The illustration shows a cross-section of the different layers of rock in the Earth's crust, both on land and the seabed. Areas along this fissure can be the source of valuable minerals. Credit: Geological Survey of Norway
The islands along the Mid-Atlantic Ridge, such as Iceland and Jan Mayen, were created from red-hot lava escaping from the Earth’s crust. The illustration shows a cross-section of the different layers of rock in the Earth’s crust, both on land and the seabed. Areas along this fissure can be the source of valuable minerals.
Credit: Geological Survey of Norway

The mid-ocean ridges where tectonic plates meet in the Atlantic and the Pacific Oceans are seething with volcanic activity. The most active areas are deep under water, several thousand metres down. Ocean water penetrates several kilometres down towards the centre of Earth where the crust is fractured. Geologists call this hydrothermal activity.

Liquid magma heats the water to about 400 °C before the water squirts back out again as an underwater geyser. The ocean water draws minerals and metals out of Earth’s crust and carries these back up to the seabed. Gold, silver, copper, cobalt, zinc, and lead are all deposited when the hot springs meet the cold ocean water.

This process formed the foundation for the land-based mines we have as well. The Norwegian ore deposits in Sulitjelma, Kongsberg and Røros were underwater 500 million years ago. But now, mines in Norway and elsewhere in the world are starting to run low on easily accessible ores. This coincides with a drastically increased demand for metals.

Several countries, including Norway, are now examining the possibility of mining the ocean floor.

Mapping the Mid-Atlantic Ridge

The Norwegian University of Science and Technology (NTNU), Statoil, and the mining company Nordic Mining are collaborating on a research project that will map marine mineral resources along the Mid-Atlantic Ridge. The parties signed a one-year collaboration agreement at the end of November 2012.

“Our primary goal is to map potential resources,” says Fredrik Søreide, an adjunct professor at NTNU’s Department of Marine Technology who is heading up the project. “We can then prioritize research and development as we move ahead.”

Researchers from the university’s Department of Geology and Mineral Resources Engineering and Applied Underwater Robotics Laboratory will also participate in this project.

The University of Bergen (UiB) has already gathered interesting samples from the Mid-Atlantic Ridge. The samples were extracted from the ridge in the area between Jan Mayen Island and the Fram Strait, off the east coast of Greenland. The researchers discovered an area of interest close to Jan Mayen in 2005. They named the area Soria Moria, after a castle in a Norwegian fairy tale.

Loki’s Castle

UiB’s scientists identified another large hydrothermal field with rich mineral deposits 300 km west of Bjørnøya in 2008. This field is located 2300 metres below the surface of the ocean. The field was named Loki’s Castle. It was hard to find, and was thus named after the Norse god Loki, who was a master of disguise. Loki’s Castle is the northernmost hydrothermal field that has been charted so far.

The researchers on the project will continue to map the ocean floor along the Mid-Atlantic Ridge for potential mineral deposits, using images from echo sounders and remotely operated submersible vessels.

“We still have many years of data collection ahead of us,” Søreide says. “But I do believe that Norway, with all of its offshore experience, is in a good position to develop this potential. It is likely that the mining industry will move offshore eventually, the same way that the petroleum industry did.

First minerals from the sea

The Canadian company Nautilus Minerals is the leader in marine mineral exploration. Nautilus Minerals has developed robotic technology for deep-sea mining in collaboration with the French company Technip. The company is planning to open the first deep-water mine in 2015. The Solwara 1 mine will be located 1600 metres below sea level. The company has found large deposits of copper and gold there. Solwara 1 is located in the Pacific Ocean, north of Australia, in Papua New Guinea.

Nautilus Minerals plans to continue searching for additional commercially viable deposits of copper, gold, zinc, and silver outside of Fiji, Tonga, the Solomon Islands, Vanuatu, and in the western part of the Pacific Ocean. Solwara 1 was supposed to start operations in 2013, but this was postponed. Local activists say that the environmental impact of the mine has not been fully investigated. The government of the independent island state of Papua New Guinea is currently negotiating with the mining company in terms of investments and profits.

Robots mining for gold

Nautilus Minerals will use submersible robots to work on the ocean floor and break apart loose ore. A pipeline will then transport the ore to a specialty vessel on the surface, which then will transport the ore to shore for refining.

“This is an extremely rich deposit of gold and copper,” says Terje Bjerkgård from Norway’s Geological Survey (NGU). He studies mineral resources and has participated in two research expeditions that included the area around Papua New Guinea.

“Underwater mining will first be commercialized in the Pacific,” he says. “The largest known deposit on the ocean floor is in Middle Valley in the northeast Pacific Ocean, off Canada. Other interesting deposits are north of New Zealand. Underwater mining will become more viable as land-based deposits become harder and more expensive to exploit. The challenges are tied to the distinct fauna around the hot springs.”

Black smokers

Rolf B. Pedersen, a professor at the University of Bergen, has been active in the exploration of the ocean floor along the Mid-Atlantic ridge. He is head of the Centre for Geobiology, which examines volcanic hydrothermal activity and the formation of the mineral resources. The Centre also conducts research on the biodiversity around underwater hot springs, including extremophile bacteria (bacteria that live in extreme environments). The Mid-Atlantic Ridge is populated by a unique fauna and flora. Scientists at the Centre discovered ten new species just in the area around Loki’s Castle. The mineral-rich water is the reason for the diversity.

Steaming chimneys called black smokers protrude from the volcanic areas at the bottom of the oceans. They can be several tens of metres tall, and grow as minerals are deposited when the hot water meets the cold ocean water at the outlet of the hydrothermal vents. Some of the metal sulphides precipitate right by the outlet, which contributes deposits that expand the structures, while the rest turn into a black smoke that the water pressure pumps into the water. The temperature of the water inside the “chimneys” can be as high as 400 °C.

The origin of life?

Hydrothermal chimneys were first observed in 1979, two years after hot springs were discovered close to the Galapagos Islands. The researchers used the submersible vessel Alvin to make the surprising discovery that volcanic areas are home to biological communities that derive their energy from chemical energy and not from sunlight. They also discovered a range of new and unknown species by the thermal vents.

The chemotrophic bacteria that live in and around the hydrothermal vents are able to use chemical energy from the mineral-rich water. The process provides all the energy this unique ecosystem requires to live. The discovery also created an understanding that the origin of life on Earth was not necessarily dependent on photosynthesis and sunlight.

“The environmental impact has not yet been examined,” says Pedersen. “The University of Bergen is a part of an international consortium that has applied for EU funding to examine the environmental impact. These special ecosystems mean it would only be appropriate to operate prospective mining operation in areas where the hydrothermal activity has ceased. However, industrial activities involve environmental consequences that have to be measured against the value of the activity.”

Obstacles beneath the surface

The problem is that inactive fields are very hard to discover with existing technology, which means that only active black smokers are currently being explored. This poses enough substantial enough challenges in and of itself, including environmental issues, technology, and great depths. Many countries are active in securing rights to underwater mineral resources, even though the start of large-scale mining efforts remains years away.

“Many countries, such as China, Russia, Japan, France and India, are positioning themselves strategically to secure resource areas in international waters,” says Søreide. “The politics of international oceans is full of intricate details, with a lot of the laws tied to the international laws of the sea.”

Interested governments have recently created rules for prospecting in international waters. Countries that have ratified the United Nations Convention on the Law of the Sea are bound by these rules. The US is among the countries that have not ratified the Convention.

Future Norwegian industry?

Norway is in special situation in regards to deep-water mining.

“Norway is unique in that these resources are within the Norwegian economic zone,” says Pedersen. “That means that underwater mining could be a future industry, when the technology is in place and if the environmental impacts are acceptable. The deposits have to be relatively big for the endeavour to be commercially profitable. There are big differences between the various estimates provided by researchers. We are trying to clarify the resource base, and need systematic studies regarding the deposits.”

This is exactly what the NTNU research project will contribute.

Note : The above story is based on materials provided by The Norwegian University of Science and Technology (NTNU), via AlphaGalileo. 

Mars once covered in giant supervolcanoes, scientists find

Colour-coded elevation image of Eden Patera, one of several sites on Mars that may be the footprints of ancient supervolcanoes. Photograph: Nasa/JPL/GSFC/Arizona State University/PA
Colour-coded elevation image of Eden Patera, one of several sites on Mars that may be the footprints of ancient supervolcanoes. Photograph: Nasa/JPL/GSFC/Arizona State University/PA

Ancient Mars was home to giant volcanoes capable of eruptions a thousand times more powerful than the one that shook Mount St Helens in 1980, scientists have said.

The finding raises fresh questions about conditions on Mars in its early years, a time when scientists believe the planet was much more Earth-like, with a thick atmosphere, warmer temperatures and water on its surface.

Major volcanic eruptions may well have triggered climate shifts that toggled Martian temperatures between cold spells when ash blocked out the sunlight and heat waves when greenhouse gases filled the skies, according to scientists.

Supervolcanoes may have made it more difficult for life to evolve on the planet’s surface, but underground steam vents and the release of water into the atmosphere also could have created niches for microbes to thrive, said geologist Joseph Michalski of the Planetary Science Institute in Tucson, Arizona.

The discovery of supervolcanoes on Mars comes from analysis of images from a quartet of Mars orbiters over the past 15 years.

These types of volcanoes, also known as “caldera” volcanoes, are ancient, collapsed structures rather than steep, cone-shaped or domed mountains like Olympus Mons on Mars, a so-called shield volcano that stands nearly three times taller than Mount Everest, the highest peak on Earth.

“We know a lot about the volcanic history of Mars over the last 3bn to 3.5bn years, but that still leaves about 1bn years before that over which we don’t really know anything about volcanism,” Michalski told Reuters.

Some scientists theorised that the oldest Martian volcanoes had eroded away, but the new findings suggest a different kind of volcano existed long ago.

“If early Mars saw a lot more explosive volcanism, then the features that are left from that don’t look like those shield volcanoes. That’s maybe why we didn’t see them,” Michalski said.

Scientists say supervolcanoes erupt with about 1,000 times the force of typical volcanoes like Mount St Helens in Washington state. The eruption of Mount St Helens in 1980 blasted the top off the mountain, killed 57 people and, according to the US Geological Survey, shot ash, steam, water and debris about 24,000 metres (80,000ft) into the air.

Evidence of past supervolcanoes on Earth has been erased by plate tectonics and other geologic activities.

Michalski was actually studying Martian impact craters, not looking for volcanoes.

“We made the discovery by accident,” he said. “As I went through [the images] of this one region, I found a number of them that were simply not impact craters,” he said.

“One was clearly a volcano. … It is quite possible there are many more of these,” Michalski added.

Because the emission of gases from volcanoes helps create a planet’s atmosphere, understanding the volcanic history of Mars is crucial to figuring out what the planet – the fourth from the Sun – was like in its early years.

Additional evidence may come from Nasa’s Mars Curiosity rover, which is heading toward a 3-mile-(5-km)-high mound of deposits called Mount Sharp.

The rover touched down inside a giant impact basin near the planet’s equator in August 2012 to assess if Mars ever had the chemistry and environment to support and preserve microbial life.

“There are thousands of layers of rocks in Mount Sharp and they contain a long record of geologic history,” Michalski said.

“There could be interlayered rocks that are ash beds, and we predict that and we hope that the rover can test it,” he said.

The research appears in the journal Nature.

Note: The above story is based on materials provided by Reuters in Houston

Crystals in Picabo’s rocks point to ‘recycled’ super-volcanic magma chambers

University of Oregon geologist Ilya Bindeman, left, and graduate student Dana Drew, working in Bindeman’s stable isotope laboratory say that the composition of zircon bits in igneous rocks in the Yellowstone hotspot track tell a new story on how super volcanoes recycle magma. Credit: University of Oregon

A thorough examination of tiny crystals of zircon, a mineral found in rhyolites, an igneous rock, from the Snake River Plain has solidified evidence for a new way of looking at the life cycle of super-volcanic eruptions in the long track of the Yellowstone hotspot, say University of Oregon scientists.

The pattern emerging from new and previous research completed in the last five years under a National Science Foundation career award, said UO geologist Ilya N. Bindeman, is that another super-eruption from the still-alive Yellowstone volcanic field is less likely for the next few million years than previously thought. The last eruption 640,000 years ago created the Yellowstone Caldera and the Lava Creek Tuff in what is now Yellowstone National Park.

The Yellowstone hotspot creates a conveyor belt style of volcanism because of the southwest migration of the North American plate at 2-4 centimeters (about .8 to 1.6 inches) annually over the last 16 million years of volcanism. Due to the movement of the North American plate, the plume interaction with the crust leaves footprints in the form of caldera clusters, in what is now the Snake River Plain, Bindeman said.

The Picabo volcanic field of southern Idaho, described in a new paper by a six-member team, was active between 10.4 and 6.6 million years ago and experienced at least three, and maybe as many as six, violent caldera-forming eruptions. The field has been difficult to assess, said lead author Dana Drew, a UO graduate student, because the calderas have been buried by as much as two kilometers of basalt since its eruption cycle died.

The work at Picabo is detailed in a paper online ahead of publication in the journal Earth and Planetary Science Letters.

The team theorized that basalt from the mantle plume, rocks from Earth’s crust and previously erupted volcanoes are melted together to form the rhyolites erupted in the Snake River Plain. Before each eruption, rhyolite magma is stored in dispersed pockets throughout the upper crust, which are later mixed together, according to geochemical evidence. “We think that this batch-assembly process is an important part of caldera-forming eruptions, and generating rhyolites in general,” Drew said.

In reaching their conclusions, Drew and colleagues analyzed radiogenic and stable isotopic data—specifically oxygen and hafnium—in zircons detected in rhyolites found at the margins of the Picabo field and from a deep borehole. That data, in combination with whole rock geochemistry and zircon uranium-lead geochronology helped provide a framework to understand the region’s ancient volcanic past.

Previous research on the related Heise volcanic field east of Picabo yielded similar results. “There is a growing database of the geochemistry of rhyolites in the Yellowstone hotspot track,” Drew said. “Adding Picabo provides a missing link in the database.

Drew and colleagues, through their oxygen isotope analyses, identified a wide diversity of oxygen ratios occurring in erupted zircons near the end of the Picabo volcanic cycle. Such oxygen ratios are referred to as delta-O-18 signatures based on oxygen 18 levels relative to seawater. (Oxygen 18 contains eight protons and 10 neutrons; Oxygen 16, with eight protons and eight neutrons, is the most commonly found form of oxygen in nature)

The approach provided a glimpse into the connection of surface and subsurface processes at a caldera cluster. The interaction of erupted rhyolite with groundwater and surface water causes hydrothermal alteration and the change in oxygen isotopes, thereby providing a fingerprinting tool for the level of hydrothermal alteration, Drew said.

“Through the eruptive sequence, we begin to generate lower delta-O-18 signatures of the magmas and, with that, we also see a more diverse signature,” Drew said. “By the time of the final eruption there is up to five per mil diversity in the signature recorded in the zircons.” The team attributes these signatures to the mixing of diverse magma batches dispersed in the upper crust, which were formed by melting variably hydrothermally altered rocks—thus diverse delta-O-18—after repeated formation of calderas and regional extension or stretching of the crust.

When the pockets of melt are rapidly assembled, the process could be the trigger for caldera forming eruptions, Bindeman said. “That leads to a homogenized magma, but in a way that preserves these zircons of different signatures from the individual pockets of melt,” he said. This research, he added, highlights the importance of using new micro-analytical isotopic techniques to relate geochemistry at the crystal-scale to processes occurring at the crustal-wide scale in generating and predicting large-volume rhyolitic eruptions.

“This important research by Dr. Bindeman and his team demonstrates the enormous impact an NSF CAREER award can have,” said Kimberly Andrews Espy, vice president for research and innovation and dean of the graduate school at the University of Oregon. “The five-year project is providing new insights into the eruption cycles of the Yellowstone hotspot and helping scientists to better predict future volcanic activity.”

Note: The above story is based on materials provided by University of Oregon

The Complicated Birth of a Volcano

A full chain bag dredge of samples obtained from the Marie Byrd Seamounts is emptied on board of POLARSTERN. (Credit: F. Hauff, GEOMAR)

They are difficult to reach, have hardly been studied scientifically, and their existence does not fit into current geological models: the Marie Byrd Seamounts off the coast of Antarctica present many riddles to volcanologists.

In the international journal “Gondwana Research,” scientists from GEOMAR Helmholtz Centre for Ocean Research Kiel in cooperation with colleagues from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research just published possible explanations for the origin of these former volcanoes and thus contributed to the decryption of complex processes in the Earth’s interior.

Snow storms, ice and glaciers — these are the usual images we associate with the Antarctic. But at the same time it is also a region of fire: the Antarctic continent and surrounding waters are dotted with volcanoes — some of them still active and others extinct for quite some time. The Marie Byrd Seamounts in the Amundsen Sea are in the latter group.

Their summit plateaus are today at depths of 2400-1600 meters. Because they are very difficult to reach with conventional research vessels, they have hardly been explored, even though the Marie Byrd Seamounts are fascinating formations.

They do not fit any of the usual models for the formation of volcanoes. Now geologists from GEOMAR Helmholtz Centre for Ocean Research Kiel were able to find a possible explanation for the existence of these seamounts on the basis of rare specimens. The study is published in the international journal “Gondwana Research.”

Classic volcanologists differentiate between two types of fire mountains. One type is generated where tectonic plates meet, so the earth’s crust is already cracked to begin with. The other type is formed within the earth’s plates. “The latter are called intraplate volcanoes. They are often found above a so-called mantle plume.

Hot material rises from the deep mantle, collects under the earth’s crust, makes its way to the surface and forms a volcano,” said Dr. Reinhard Werner, one of the authors of the current paper. One example are the Hawaiian Islands. But neither of the above models fits the Marie Byrd Seamounts. “There are no plate boundaries in the vicinity and no plumes underground,” says graduate geologist Andrea Kipf from GEOMAR, first author of the study.

To clarify the origin of the Marie Byrd Seamounts, in 2006 the Kiel scientists participated in an expedition of the research vessel POLARSTEN in the Amundsen Sea. They salvaged rock samples from the seamounts and subjected these to thorough geological, volcanological and geochemical investigations after returning to the home labs. “Interestingly enough, we found chemical signatures that are typical of plume volcanoes. And they are very similar to volcanoes in New Zealand and the Antarctic continent,” says geochemist Dr. Folkmar Hauff, second author of the paper.

Based on this finding, the researchers sought an explanation. They found it in the history of tectonic plates in the southern hemisphere. Around 100 million years ago, remains of the former supercontinent Gondwana were located in the area of present Antarctica. A mantle plume melted through this continental plate and cracked it open.

Two new continents were born: the Antarctic and “Zealandia,” with the islands of New Zealand still in evidence today. When the young continents drifted in different directions away from the mantle plume, large quantities of hot plume material were attached to their undersides. These formed reservoirs for future volcanic eruptions on the two continents. “This process explains why we find signatures of plume material at volcanoes that are not on top of plumes,” says Dr. Hauff.

But that still does not explain the Marie Byrd Seamounts because they are not located on the Antarctic continent, but on the adjacent oceanic crust instead. “Continental tectonic plates are thicker than the oceanic ones. This ensures, among other things, differences in temperature in the underground,” says volcanologist Dr. Werner. And just as air masses of different temperatures create winds, the temperature differences under the earth’s crust generate flows and movements as well. Thus the plume material, that once lay beneath the continent, was able to shift under the oceanic plate.

With disruptions due to other tectonic processes, there were cracks and crevices which allowed the hot material to rise, turn into magma and then- about 60 million years ago — allowed the Marie Byrd Seamounts to grow. “This created islands that are comparable to the Canary Islands today,” explains Andrea Kipf. “Some day the volcanoes became extinct again, wind and weather eroded the cone down to sea level, and other geological processes further eroded the seamounts. Finally, the summit plateaus arrived at the level that we know today,” the PhD student describes the last step of the development.

Based on the previously little investigated Marie Byrd Seamounts, the researchers were able to show another example of how diverse and complex the processes are, that can cause volcanism. “We are still far from understanding all of these processes. But with the current study, we can contribute a small piece to the overall picture,” says Dr. Werner.

Note: The above story is based on materials provided by Helmholtz Centre for Ocean Research Kiel (GEOMAR).

Crystals in Picabo’s Rocks Point to ‘Recycled’ Super-Volcanic Magma Chambers

Map showing Picabo and Heise fields. (Credit: University of Oregon)

A thorough examination of tiny crystals of zircon, a mineral found in rhyolites, an igneous rock, from the Snake River Plain has solidified evidence for a new way of looking at the life cycle of super-volcanic eruptions in the long track of the Yellowstone hotspot, say University of Oregon scientists.

The pattern emerging from new and previous research completed in the last five years under a National Science Foundation career award, said UO geologist Ilya N. Bindeman, is that another super-eruption from the still-alive Yellowstone volcanic field is less likely for the next few million years than previously thought (see related story, “Not in a million years, says Oregon geologist about Yellowstone eruption”). The last eruption 640,000 years ago created the Yellowstone Caldera and the Lava Creek Tuff in what is now Yellowstone National Park.

The Yellowstone hotspot creates a conveyor belt style of volcanism because of the southwest migration of the North American plate at 2-4 centimeters (about .8 to 1.6 inches) annually over the last 16 million years of volcanism. Due to the movement of the North American plate, the plume interaction with the crust leaves footprints in the form of caldera clusters, in what is now the Snake River Plain, Bindeman said.

The Picabo volcanic field of southern Idaho, described in a new paper by a six-member team, was active between 10.4 and 6.6 million years ago and experienced at least three, and maybe as many as six, violent caldera-forming eruptions. The field has been difficult to assess, said lead author Dana Drew, a UO graduate student, because the calderas have been buried by as much as two kilometers of basalt since its eruption cycle died.

The work at Picabo is detailed in a paper online ahead of publication in the journal Earth and Planetary Science Letters.

The team theorized that basalt from the mantle plume, rocks from Earth’s crust and previously erupted volcanoes are melted together to form the rhyolites erupted in the Snake River Plain. Before each eruption, rhyolite magma is stored in dispersed pockets throughout the upper crust, which are later mixed together, according to geochemical evidence. “We think that this batch-assembly process is an important part of caldera-forming eruptions, and generating rhyolites in general,” Drew said.

In reaching their conclusions, Drew and colleagues analyzed radiogenic and stable isotopic data — specifically oxygen and hafnium — in zircons detected in rhyolites found at the margins of the Picabo field and from a deep borehole. That data, in combination with whole rock geochemistry and zircon uranium-lead geochronology helped provide a framework to understand the region’s ancient volcanic past.

Previous research on the related Heise volcanic field east of Picabo yielded similar results. “There is a growing database of the geochemistry of rhyolites in the Yellowstone hotspot track,” Drew said. “Adding Picabo provides a missing link in the database.

Drew and colleagues, through their oxygen isotope analyses, identified a wide diversity of oxygen ratios occurring in erupted zircons near the end of the Picabo volcanic cycle. Such oxygen ratios are referred to as delta-O-18 signatures based on oxygen 18 levels relative to seawater. (Oxygen 18 contains eight protons and 10 neutrons; Oxygen 16, with eight protons and eight neutrons, is the most commonly found form of oxygen in nature.)

The approach provided a glimpse into the connection of surface and subsurface processes at a caldera cluster. The interaction of erupted rhyolite with groundwater and surface water causes hydrothermal alteration and the change in oxygen isotopes, thereby providing a fingerprinting tool for the level of hydrothermal alteration, Drew said.

“Through the eruptive sequence, we begin to generate lower delta-O-18 signatures of the magmas and, with that, we also see a more diverse signature,” Drew said. “By the time of the final eruption there is up to five per mil diversity in the signature recorded in the zircons.” The team attributes these signatures to the mixing of diverse magma batches dispersed in the upper crust, which were formed by melting variably hydrothermally altered rocks — thus diverse delta-O-18 — after repeated formation of calderas and regional extension or stretching of the crust.

When the pockets of melt are rapidly assembled, the process could be the trigger for caldera forming eruptions, Bindeman said. “That leads to a homogenized magma, but in a way that preserves these zircons of different signatures from the individual pockets of melt,” he said. This research, he added, highlights the importance of using new micro-analytical isotopic techniques to relate geochemistry at the crystal-scale to processes occurring at the crustal-wide scale in generating and predicting large-volume rhyolitic eruptions.

“This important research by Dr. Bindeman and his team demonstrates the enormous impact an NSF CAREER award can have,” said Kimberly Andrews Espy, vice president for research and innovation and dean of the graduate school at the University of Oregon. “The five-year project is providing new insights into the eruption cycles of the Yellowstone hotspot and helping scientists to better predict future volcanic activity.”

Note : The above story is based on materials provided by University of Oregon. 

Iron in Earth’s Core Weakens Before Melting

The iron in Earth’s inner core weakens dramatically before it melts, explaining the unusual properties that exist in the moon-sized solid center of our planet that have, up until now, been difficult to understand. (Credit: iStockphoto)

The iron in the Earth’s inner core weakens dramatically before it melts, explaining the unusual properties that exist in the moon-sized solid centre of our planet that have, up until now, been difficult to understand.

Scientists use seismic waves — pulses of energy generated during earthquakes — to measure what is happening in the Earth’s inner core, which at 6000 km beneath our feet is completely inaccessible.

Problematically for researchers, the results of seismic measurements consistently show that these waves move through the Earth’s solid inner core at much slower speeds than predicted by experiments and simulations.

Specifically, a type of seismic wave called a ‘shear wave’ moves particularly slowly through the Earth’s core relative to the speed expected for the material — mainly iron — from which the core is made. Shear waves move through the body of the object in a transverse motion — like waves in a rope, as opposed to waves moving through a slinky spring.

Now, in a paper published in Science, scientists from UCL have proposed a possible explanation. They suggest that the iron in the Earth’s core may weaken dramatically just before melting, becoming much less stiff. The team used quantum mechanical calculations to evaluate the wave velocities of solid iron at inner-core pressure up to melting.

They calculated that at temperatures up to 95% of what is needed to melt iron in the Earth’s inner core, the speed of the seismic waves moving through the inner core decreases linearly but, after 95%, it drops dramatically.

At about 99% of the melting temperature of iron, the team’s calculated velocities agree with seismic data for the Earth’s inner core. Since independent geophysical results suggest that the inner core is likely to be at 99-100% of its melting temperature, the results presented in this paper give a compelling explanation as to why the seismic wave velocities are lower than those predicted previously.

Professor Lidunka Vočadlo, from the UCL department of Earth Sciences and an author of the paper said: “The Earth’s deep interior still holds many mysteries that scientists are trying to unravel.

“The proposed mineral models for the inner core have always shown a faster wave speed than that observed in seismic data. This mismatch has given rise to several complex theories about the state and evolution of the Earth’s core.”

The authors stress that this is not the end of the story as other factors need to be taken into account before a definitive core model can be made. As well as iron, the core contains nickel and light elements, such as silicon and sulphur.

Professor Vočadlo said: “The strong pre-melting effects in iron shown in our paper are an exciting new development in understanding the Earth’s inner core. We are currently working on how this result is affected by the presence of other elements, and we may soon be in a position to produce a simple model for the inner core that is consistent with seismic and other geophysical measurements. ”

Note : The above story is based on materials provided by University College London, via EurekAlert!, a service of AAAS. 

Iron Melt Network Helped Grow Earth’s Core, Study Suggests

In a rock and metal sample created by Stanford scientists to mimic the make up of the early Earth mantle, drops of molten iron merge to form a network. In this X-ray tomography image of the sample, the channels labeled in blue are interconnected. (Credit: Crystal Shi)

Stanford scientists recreated the intense pressures and temperatures found deep within Earth, resulting in a discovery that complicates theories of how the planet and its core were formed.

The same process that allows water to trickle through coffee grinds to create your morning espresso may have played a key role in the formation of the early Earth and influenced its internal organization, according to a new study by scientists at Stanford’s School of Earth Sciences.

The finding, published in the current issue of the journal Nature Geoscience, lends credence to a theory first proposed nearly half a century ago suggesting that Earth’s iron-rich core and layered internal structure might have formed in a series of steps that took place over millions of years under varying temperature and pressure conditions.

“We know that Earth today has a core and a mantle that are differentiated. With improving technology, we can look at different mechanisms of how this came to be in a new light,” said study leader Wendy Mao, an assistant professor of geological and environmental sciences at Stanford, and of photon sciences at the SLAC National Accelerator Laboratory, which is operated by the university.

Earth’s innards are presently divided into layers, with the rocky mantle composed mostly of silicates overlying an iron-rich metallic core. How the planet came to have this orderly arrangement is a major mystery, especially since scientists think its beginnings were messy and chaotic, the result of small bodies made up of rock and metals crashing and clumping together shortly after the formation of the sun and the birth of the solar system some 4.5 billion years ago.

How did Earth evolve from this conglomerated mass of rocks and metals into its current layered state?

Separating metal from rock

One idea is that the heat generated by the collisions and by the radioactive decay of certain isotopes warmed Earth. The planet could have gotten so hot that its rocks and metals melted. The molten rocks and metals in this “magma ocean” would then have separated into distinct layers as a result of their different densities. Iron would have drifted downward towards the planet’s center, while silicates remained on top.

Other scientists have proposed that even if the early Earth’s temperature was not hot enough to melt silicates, the molten iron might still have separated out by percolating through the solid silicate layer.

The thought was that pockets of molten iron trapped in the mantle layer could tunnel through the surrounding rock to create channels, or capillaries. This network of tunnels could have helped funnel molten iron towards the planet’s center to join the spherical metallic heart that was slowly amassing there.

However, this “percolation” theory was dealt a major blow when scientists discovered that, in the upper mantle layer at least, the molten iron tended to form isolated spheres that didn’t interact with one another, similar to the way water beads up on a waxed surface.

For this reason, scientists had previously thought that percolation couldn’t be possible, Mao said.

Recreating ancient Earth

But a new experiment conducted by Mao and her team uncovered fresh evidence that percolation might still be a viable mechanism for explaining the formation of Earth’s core.

Working with researchers at the U.S. Department of Energy’s SLAC facility, Mao and her team recreated a speck of the molten silicate and iron material that scientists believe existed deep inside the early Earth.

To do this, Mao’s team placed minute amounts of iron and silicate rock into a metal chamber that they then inserted between the tips of two small diamonds. Squeezing these “diamond anvils” together recreated the immense pressures present in Earth’s interior, and a laser beam was used to heat the sample to a high enough temperature to melt the iron.

After the sample cooled, the scientists examined it using X-ray-computed tomography. Tomography creates a three-dimensional image of an object by combining a series of two-dimensional slices. A computer program then helps flesh out the re-creation of the object.

A state-of-the-art X-ray microscope at SLAC allowed Mao’s team to resolve nanometer-scale details in their sample of heated silicates and iron. The higher resolution allowed the scientists to observe never-before-seen changes in the texture and shape of the molten iron and silicates as they responded to the same intense pressures and temperatures that were present deep in the early Earth.

Which happened first?

The experiment confirmed the findings from previous studies that molten iron in the upper mantle tended to form isolated blobs, which would have prevented percolation from happening. “In order for percolation to be efficient, the molten iron needs to be able to form continuous channels through the solid,” Mao explained.

However, the scientists found that at the higher pressures and temperatures that would have been present in the early Earth’s lower mantle, the structure of the silicates changed in a way that permitted connections to form between pockets of molten iron, making percolation possible.

“Scientists had said this theory wasn’t possible, but now we’re saying, under certain conditions that we know exist in the planet, it could happen,” Mao said. “So this brings back another possibility for how the core might have formed.”

The team’s new findings do not rule out the possibility that differentiation began when Earth was in a magma ocean state. In fact, both mechanisms could have occurred, said study first author Crystal Shi, a graduate student in Mao’s lab.

“We don’t know which mechanism happened first, or if the two happened together,” Shi said. “At the very beginning, Earth would have still been very hot, and the magma ocean mechanism could have been important. But later as the planet cooled, percolation may have become the dominant mechanism.”

Scientists from China’s Center for High Pressure Science and Technology Advanced Research, and the Carnegie Institution of Washington also contributed to this research.

Note : The above story is based on materials provided by Stanford University.

First Ever Evidence of a Comet Striking Earth

An artist’s rendition of the comet exploding in Earth’s atmosphere above Egypt. (Credit: Terry Bakker)

The first ever evidence of a comet entering Earth’s atmosphere and exploding, raining down a shock wave of fire which obliterated every life form in its path, has been discovered by a team of South African scientists and international collaborators.

The discovery has not only provided the first definitive proof of a comet striking Earth, millions of years ago, but it could also help us to unlock, in the future, the secrets of the formation of our solar system.

“Comets always visit our skies — they’re these dirty snowballs of ice mixed with dust — but never before in history has material from a comet ever been found on Earth,” says Professor David Block of Wits University.

The comet entered Earth’s atmosphere above Egypt about 28 million years ago. As it entered the atmosphere, it exploded, heating up the sand beneath it to a temperature of about 2,000 degrees Celsius, and resulting in the formation of a huge amount of yellow silica glass which lies scattered over a 6,000 square kilometre area in the Sahara. A magnificent specimen of the glass, polished by ancient jewellers, is found in Tutankhamun’s brooch with its striking yellow-brown scarab.

The research, which will be published in Earth and Planetary Science Letters, was conducted by a collaboration of geoscientists, physicists and astronomers including Block, lead author Professor Jan Kramers of the University of Johannesburg, Dr Marco Andreoli of the South African Nuclear Energy Corporation, and Chris Harris of the University of Cape Town.

At the centre of the attention of this team was a mysterious black pebble found years earlier by an Egyptian geologist in the area of the silica glass. After conducting highly sophisticated chemical analyses on this pebble, the authors came to the conclusion that it represented the very first known hand specimen of a comet nucleus, rather than simply an unusual type of meteorite.

Kramers describes this as a moment of career defining elation. “It’s a typical scientific euphoria when you eliminate all other options and come to the realisation of what it must be,” he said.

The impact of the explosion also produced microscopic diamonds. “Diamonds are produced from carbon bearing material. Normally they form deep in the Earth, where the pressure is high, but you can also generate very high pressure with shock. Part of the comet impacted and the shock of the impact produced the diamonds,” says Kramers.

The team have named the diamond-bearing pebble “Hypatia” in honour of the first well known female mathematician, astronomer and philosopher, Hypatia of Alexandria.

Comet material is very elusive. Comet fragments have not been found on Earth before except as microscopic sized dust particles in the upper atmosphere and some carbon-rich dust in the Antarctic ice. Space agencies have spent billions to secure the smallest amounts of pristine comet matter.

“NASA and ESA (European Space Agency) spend billions of dollars collecting a few micrograms of comet material and bringing it back to Earth, and now we’ve got a radical new approach of studying this material, without spending billions of dollars collecting it,” says Kramers.

The study of Hypatia has grown into an international collaborative research programme, coordinated by Andreoli, which involves a growing number of scientists drawn from a variety of disciplines. Dr Mario di Martino of Turin’s Astrophysical Observatory has led several expeditions to the desert glass area.

“Comets contain the very secrets to unlocking the formation of our solar system and this discovery gives us an unprecedented opportunity to study comet material first hand,” says Block.

Note : The above story is based on materials provided by Wits University. 

Extrusive Volcanism Formed the Hawaiian Islands

This is a 3D perspective view of the topography of the Hawaiian Islands (gray shaded) and seafloor relief viewed from just south of the Hawaii’s Big Island. The colors show residual gravity anomaly, measured on land and along ship tracks: Red-cyan representing an excess pull of gravity, blue representing a small deficit in the pull of gravity. (Credit: Ashton Flinders, UHM SOEST.)

A recent study by researchers at the University of Hawaii — Manoa (UHM) School of Ocean and Earth Science and Technology (SOEST) and the University of Rhode Island (URI) changes the understanding of how the Hawaiian Islands formed. Scientists have determined that it is the eruptions of lava on the surface, extrusion, which grow Hawaiian volcanoes, rather than internal emplacement of magma, as was previously thought.

Before this work, most scientists thought that Hawaiian volcanoes grew primarily internally — by magma intruding into rock and solidifying before it reaches the surface. While this type of growth does occur, along Kilauea’s East Rift Zone (ERZ), for example, it does not appear to be representative of the overall history of how the Hawaiian Islands formed. Previous estimates of the internal-to-extrusive ratios (internally emplaced magma versus extrusive lava flow) were based on observations over a very short time frame, in the geologic sense.

Ashton Flinders (M.S. from UHM), lead author and graduate student at URI, and colleagues compiled historical land-based gravity surveys with more recent surveys on the Big Island of Hawaii (in partnership with Jim Kauahikaua of the U.S. Geological Survey — Hawaii Volcano Observatory) and Kauai, along with marine surveys from the National Geophysical Data Center and from the UH R/V Kilo Moana. These types of data sets allow scientists to infer processes that have taken place over longer time periods.

“The discrepancy we see between our estimate and these past estimates emphasizes that the short term processes we currently see in Hawaii (which tend to be more intrusive) do not represent the predominant character of their volcanic activity,” said Flinders.

“This could imply that over the long-term, Kilauea’s ERZ will see less seismic activity and more eruptive activity that previously thought. The 3-decade-old eruption along Kilauea’s ERZ could last for many, many more decades to come,” said Dr. Garrett Ito, Professor of Geology and Geophysics at UHM and co-author.

“I think one of the more interesting possible implications is how the intrusive-to-extrusive ratio impacts the stability of the volcano’s flank. Collapses occur over a range of scales from as large as the whole flank of a volcano, to bench collapses on the south coast of Big Island, to small rock falls. ” said Flinders. Intrusive magma is more dense and structurally stronger than lava flows. “If the bulk of the islands are made from these weak extrusive flows then this would account for some of the collapses that have been documented, but this is mainly just speculation as of now.”

The authors hope this new density model can be used as a starting point for further crustal studies in the Hawaiian Islands.

Note : The above story is based on materials provided by University of Hawaii ‑ SOEST, via EurekAlert!, a service of AAAS. 

Exceptional fossil fish reveals new evolutionary mechanism for body elongation

The 240-million-year-old fossil find from Switzerland also revealed that this primitive fish was not as flexible as today’s eels, nor could it swim as fast or untiringly as a tuna. Credit: Picture: UZH

Snake and eel bodies are elongated, slender and flexible in all three dimensions. This striking body plan has evolved many times independently in the more than 500 million years of vertebrate animals history.

Based on the current state of knowledge, the extreme elongation of the body axis occurred in one of two ways: either through the elongation of the individual vertebrae of the vertebral column, which thus became longer, or through the development of additional vertebrae and associated muscle segments.

Long body thanks to doubling of the vertebral arches

A team of paleontologists from the University of Zurich headed by Professor Marcelo Sánchez-Villagra now reveal that a third, previously unknown mechanism of axial skeleton elongation characterized the early evolution of fishes, as shown by an exceptionally preserved form.
Unlike other known fish with elongate bodies, the vertebral column of Saurichthys curionii does not have one vertebral arch per myomeric segment, but two, which is unique. This resulted in an elongation of the body and gave it an overall elongate appearance.
“This evolutionary pattern for body elongation is new,” explains Erin Maxwell, a postdoc from Sánchez-Villagra’s group. “Previously, we only knew about an increase in the number of vertebrae and muscle segments or the elongation of the individual vertebrae.”
The fossils studied come from the Monte San Giorgio find in Ticino, which was declared a world heritage site by UNESCO in 2003. The researchers owe their findings to the fortunate circumstance that not only skeletal parts but also the tendons and tendon attachments surrounding the muscles of the primitive predatory fish had survived intact.
Due to the shape and arrangement of the preserved tendons, the scientists are also able to draw conclusions as to the flexibility and swimming ability of the fossilized fish genus. According to Maxwell, Saurichthys curionii was certainly not as flexible as today’s eels and, unlike modern oceanic fishes such as tuna, was probably unable to swim for long distances at high speed.
Based upon its appearance and lifestyle, the roughly half-meter-long fish is most comparable to the garfish or needlefish that exist today.
Note : The above story is based on materials provided by University of Zurich

Climate Puzzle Over Origins of Life On Earth

The ancient air was trapped in old and well-presereved rocks in north Australia. (Credit: Image courtesy of Manchester University)

The mystery of why life on Earth evolved when it did has deepened with the publication of a new study in the latest edition of the journal Science.

Scientists at the CRPG-CNRS University of Lorraine, The University of Manchester and the Institut de Physique du Globe de Paris have ruled out a theory as to why the planet was warm enough to sustain the planet’s earliest life forms when the Sun’s energy was roughly three-quarters the strength it is today.

Life evolved on Earth during the Archean, between 3.8 and 2.4 billion years ago, but the weak Sun should have meant the planet was too cold for life to take hold at this time; scientists have therefore been trying to find an explanation for this conundrum, what is dubbed the ‘faint, young Sun paradox’.

“During the Archean the solar energy received at the surface of the Earth was about 20 to 25 % lower than present,” said study author, Dr Ray Burgess, from Manchester’s School of Earth, Atmospheric and Environmental Sciences. “If the greenhouse gas composition of the atmosphere was comparable to current levels then the Earth should have been permanently glaciated but geological evidence suggests there were no global glaciations before the end of the Archean and that liquid water was widespread.”

One explanation for the puzzle was that greenhouse gas levels — one of the regulators of Earth’s climate — were significantly higher during the Archean than they are today.

“To counter the effect of the weaker Sun, carbon dioxide concentrations in the Earth’s atmosphere would need to have been 1,000 times higher than present,” said lead author Professor Bernard Marty, from the CRPG-CNRS University of Lorraine. “However, ancient fossil soils — the best indicators of ancient carbon dioxide levels in the atmosphere — suggest only modest levels during the Archean. Other atmospheric greenhouse gases were also present, in particular ammonia and methane, but these gases are fragile and easily destroyed by ultraviolet solar radiation, so are unlikely to have had any effect.”

But another climate-warming theory — one the team wanted to test — is that the amount of nitrogen could have been higher in the ancient atmosphere, which would amplify the greenhouse effect of carbon dioxide and allow Earth to remain ice-free.

The team analysed tiny samples of air trapped in water bubbles in quartz from a region of northern Australia that has extremely old and exceptionally well-preserved rocks.

“We measured the amount and isotopic abundances of nitrogen and argon in the ancient air,” said Professor Marty. “Argon is a noble gas which, being chemically inert, is an ideal element to monitor atmospheric change. Using the nitrogen and argon measurements we were able to reconstruct the amount and isotope composition of the nitrogen dissolved in the water and, from that, the atmosphere that was once in equilibrium with the water.”

The researchers found that the partial pressure of nitrogen in the Archean atmosphere was similar, possibly even slightly lower, than it is at present, ruling out nitrogen as one of the main contenders for solving the early climate puzzle.

Dr Burgess added: “The amount of nitrogen in the atmosphere was too low to enhance the greenhouse effect of carbon dioxide sufficiently to warm the planet. However, our results did give a higher than expected pressure reading for carbon dioxide — at odds with the estimates based on fossil soils — which could be high enough to counteract the effects of the faint young Sun and will require further investigation.”

Note : The above story is based on materials provided by Manchester University. 

Radioactive shale gas contaminants found at wastewater discharge site

Marcellus shale along Rt 174 just south of Slate Hill Rd, Marcellus, NY Author : Lvklock ” Wikimedia”

DURHAM, N.C. — Elevated levels of radioactivity, salts and metals have been found in river water and sediments at a site where treated water from oil and gas operations is discharged into a western Pennsylvania creek.

“Radium levels were about 200 times greater in sediment samples collected where the Josephine Brine Treatment Facility discharges its treated wastewater into Blacklick Creek than in sediment samples collected just upstream of the plant,” said Avner Vengosh, professor of geochemistry and water quality at Duke University’s Nicholas School of the Environment.

The new Duke study examined the quality of shale gas wastewater from hydraulic fracturing and the stream water above and below the disposal site. The study found that some of the discharged effluent is derived from the Marcellus shale gas flowback water, which is naturally high in salinity and radioactivity.

High concentrations of some salts and metals were also observed in the stream water. “The treatment removes a substantial portion of the radioactivity, but it does not remove many of the other salts, including bromide,” Vengosh said. “When the high-bromide effluents are discharged to the stream, it increases the concentrations of bromide above the original background levels. This is significant because bromide increases the risks for formation of highly toxic disinfection byproducts in drinking water treatment facilities that are located downstream.”

“The radioactivity levels we found in sediments near the outflow are above management regulations in the U.S. and would only be accepted at a licensed radioactive disposal facility,” said Robert B. Jackson, professor of environmental science at Duke. “The facility is quite effective in removing metals such as barium from the water but concentrates sulfates, chlorides and bromides. In fact this single facility contributes four-fifths of the total downstream chloride flow at this point.”

The Duke team also analyzed stream-bottom sediments for radium isotopes that are typically found in Marcellus wastewater. “Although the facility’s treatment process significantly reduced radium and barium levels in the wastewater, the amount of radioactivity that has accumulated in the river sediments still exceeds thresholds for safe disposal of radioactive materials,” Vengosh said. “Years of disposal of oil and gas wastewater with high radioactivity has created potential environmental risks for thousands of years to come.”

“While water contamination can be mitigated by treatment to a certain degree, our findings indicate that disposal of wastewater from both conventional and unconventional oil and gas operations has degraded the surface water and sediments,” said Nathaniel R. Warner, a recent Ph.D. graduate of Duke who is now a postdoctoral researcher at Dartmouth College. “This could be a long-term legacy of radioactivity.”

Industry has made efforts to reuse or to transport shale gas wastewater to deep injection wells, but wastewater is still discharged to the environment in some states. “It is clear that this practice of releasing wastewater without adequate treatment should be stopped in order to protect freshwater resources in areas of oil and gas development,” Vengosh said.

The Duke team published their findings Oct. 2 in the peer-reviewed journal Environmental Science & Technology.

Note : The above story is based on materials provided by  Duke University

Oldest Lizard-Like Fossil Yet to Be Found Hints at Scaly Origins

Top: Vellberg jaw. Bottom: restoration image. (Credit: Marc Jones)

The fossilised remains of a reptile closely related to lizards are the oldest yet to be discovered.

Two new fossil jaws discovered in Vellberg, Germany provide the first direct evidence that the ancestors of lizards, snakes and tuatara (known collectively as lepidosaurs) were alive during the Middle Triassic period — around 240 million years ago.

The new fossil finds predate all other lepidosaur records by 12 million years. The findings are published in BMC Evolutionary Biology.

The international team of scientists who dated the fossil jaws have provided evidence that lepidosaurs first appeared after the end-Permian mass extinction event, a period when fauna began to recover and thrive in the more humid climate.

Lead author Dr Marc Jones, who conducted the research at UCL, explained: “The Middle Triassic represents a time when the world has recovered from the Permian mass extinction but is not yet dominated by dinosaurs. This is also when familiar groups, such as frogs and lizards, may have first appeared.”

The small teeth and lightly built jaws suggest that the extinct animal preyed on small insects. The new fossils are most closely related to the tuatara, a lizard-like reptile.

Tuatara can be found on 35 islands lying off the coast of New Zealand and were recently reintroduced to the mainland. However, they are the sole survivors of a group that was once as globally widespread as lizards are today. Tuatara feed on beetles, spiders, crickets and small lizards, also enjoying the occasional sea bird.

Today, there are over 9,000 species of lizards, snakes and tuatara. Knowing when the common ancestor of this grouping first appeared is crucial for understanding the ecological context in which it first evolved as well as its subsequent diversification.

To establish the age of the fossil remains, biologists use a dating technique known as a “molecular clock.” This method compares the amount of genetic divergence between living animals, caused by changes in their DNA sequences that have accumulated since they split from a common ancestor. These mutations occur fairly regularly, ticking along at a clock-like rate. However, for the clock to convert genetic differences into geological time, it has to be calibrated using one or more fossils of known relationship and time.

Molecular clocks have been used by biologists to answer questions as important as when the first modern humans emerged, and when humans and chimpanzees shared a common ancestor. The new fossil jaws can improve molecular dating estimates of when reptiles began to diversify into snakes, lizard and tuatara, and when the first modern lizards inhabited the earth. Previous estimates have varied over a range of 64 million years and the team are keen to help narrow this down.

“Some previous estimates based on molecular data suggested that lizards first evolved 290 million years ago,” said second author Cajsa Lisa Anderson, University of Gothenburg. “To a palaeontologist this seems way too old and our revised molecular analysis agrees with the fossils.”

Revised molecular dating in light of this new fossil find now suggests lizards began to diversify into most of the modern groups we recognise today, such as geckos and skinks, less than 150 million years ago in the Cretaceous period, following continental fragmentation.

The specimens were collected and initially identified by Professor Rainer Schoch from the Staatliches Museum für Naturkunde in Stuttgart, where the specimens are now registered.

Scientists anticipate that the Vellberg site will yield yet more fossil discoveries in the future, broadening our knowledge of the vertebrate fossil record.

Co-Author Professor Susan Evans, from the UCL Department of Cell and Developmental Biology, said: “The fossil record of small animals such as lizards and frogs is very patchy. Hopefully, this new fossil site in Germany will eventually give us a broader understanding of what was going on at this time.”

Note : The above story is based on materials provided by University College London, via EurekAlert!, a service of AAAS. 

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