They used the vibroseis seismic reflection technique for this survey, whereby a series of trucks create a seismic signal by vibrating heavy plates laid on the ground through a series of known frequencies. Credit: Riff Raf
Geologists have come to the tentative conclusion that relatively young Mesoproterozoic bedrock lies deep beneath the Nullabor, wedged between two much older formations.
These formations are the Yilgarn Craton to the west and South Australia’s Gawler Craton, both former tectonic plates.
Geological Survey of Western Australia geologist Ian Tyler says data from a seismic survey along 860 km of railway line, from Haig east of Kalgoolie to Tarcoola in South Australia, is still being interpreted.
It covers largely under-explored areas between two of the world’s most prospective geological regions.
Dr Tyler says the survey, completed in February, completes an east–west transect of the continent to study the Australian crust’s structure.
“People may be more familiar with seismic surveys where they look at fairly shallow depths to around five or six kilometres, looking for oil in shallow basins,” he says.
“What we’ve been doing over the last 15 years or so in Australia is looking at greater depths to the full depth of the crust.”
He says they used the vibroseis seismic reflection technique for this survey, whereby a series of trucks create a seismic signal by vibrating heavy plates laid on the ground through a series of known frequencies.
As it travels through the earth’s crust, various surfaces within the crust reflect the signal back, where geophones laid along the ground detect it.
By listening for 20 seconds, they are able to pick up signals to a depth of 60 km, being the thickness of the Earth’s crust.
He says very little is currently known about the province’s geology as it is has no outcrops, being covered by about 400 m of limestone, concealing deeper structures.
Geological structures likened to old basement
“First of all you’ve got the Eucla Basin sitting on top which is an old sea floor essentially sitting on an old basement.
“But the rocks underneath are like nothing we’ve probably seen in outcrops anywhere else on the Australian continent.”
He says they gained additional information about these rocks by drilling eight stratigraphic holes through the limestone.
The basement structure appears to be a much younger piece of crust, 1600-1000 million years old, trapped between Archean era Yilgarn and Gawler Cratons.
“This may represent a history of ocean basin closure and collision during that period but this is speculation,” Dr Tyler says.
“We are in the middle of the processing period so we won’t actually release the data to the public until it’s been processed.”
Note : The above story is based on materials provided by Science Network WA
Scientists now think that magma moves from deeper pools, or sub-axial magma lenses (SAML), to a shallow pool, or axial magma lens (AML), a mile or so beneath the seafloor. (Marjanovic)
Two-thirds of earth’s surface is covered in oceanic crust, but the deep plumbing that generates new crust remains poorly understood. New images from a chain of volcanoes beneath the Pacific Ocean show that magma may be erupting from a multi-layered magma chamber extending two miles or more beneath the seafloor, far deeper than originally thought.
The pictures, in the latest issue of Nature Geoscience, may help resolve a debate about how new crust forms at mid-ocean ridges where earth’s tectonic plates are slowly pulling apart. In one hypothesis, the lower crust is formed as a shallow pool of magma beneath the volcanic spreading center solidifies, forming a kind of crystalline glacier that oozes down and out, like hot fudge over a sundae. In another view, pools of magma stacked vertically form new rocks at depths throughout the crust, and send lava to earth’s surface, creating the upper and lower crust in one fell swoop. The new images seem to support the multi-tier view, predicted by geologists who have studied eroded oceanic crust on land.
“We now see that during an eruption we may have magma moving from one level to another,” said study coauthor Suzanne Carbotte, a geophysicist at Columbia University’s Lamont-Doherty Earth Observatory.
The pictures come from a 2008 research expedition to the East Pacific Rise, a chain of submarine volcanoes that run from California’s Salton Sea to the northern shores of Antarctica. Aboard the R/V Langseth, the scientists used pulses of sound to map the sub-seafloor beneath a region that saw massive eruptions from 2005 to 2006. In the sub-surface images, Carbotte and former Lamont graduate student Milena Marjanovic and others on the cruise recognized multi-layered magma pools, or “melt lenses,” stacked one on top of the other. In addition, these multiple tiers looked as if they had been connected during the eruption.
A multi-tier magma chamber had been predicted in 1998 by Lamont-Doherty geophysicist Peter Kelemen and colleagues based on field observations in the Middle Eastern nation of Oman, where mantle peridotites formerly at the bottom of the ocean have been heaved onto land, providing easy access. Kelemen and colleagues discovered that rocks in close proximity had different chemical signatures. That would be impossible if a slow-oozing crystalline mush had created them. To Kelemen, Oman’s uneven but undeformed rock layers, too, seemed inconsistent with such a model.
“We could identify some bodies of rock that surely had formed in deeper melt lenses within the uppermost mantle, and we showed that they were very similar to the rocks throughout the crust,” said Kelemen, who was not involved in the Nature Geoscience study.
“We hoped that someday techniques would improve and the deeper lenses would emerge from their obscurity,” he added. “With the dedication and hard work of many research teams, this finally seems to be happening.”
More information:
“A multi-sill magma plumbing system beneath the axis of the East Pacific Rise” Nature Geoscience (2014) DOI: 10.1038/ngeo2272
Note : The above story is based on materials provided by Columbia University
Aerial photo of the San Andreas Fault in the Carrizo Plain, northwest of Los Angeles. Credit: Wikipedia.
The last ten years have been a remarkable time for great earthquakes. Since December 2004 there have been no less than 18 quakes of Mw8.0 or greater – a rate of more than twice that seen from 1900 to mid-2004. Hundreds of thousands of lives have been lost and massive damage has resulted from these great earthquakes. But as devastating as such events can be, these recent great quakes have come with a silver lining: They coincide with unprecedented advances in technological and scientific capacity for learning from them.
“We previously had very limited information about how ruptures grow into great earthquakes and interact with regions around them,” said seismologist Thorne Lay of the University of California at Santa Cruz. “So we are using the recorded data for these recent events to guide our understanding of future earthquakes. We’ve gained a new level of appreciation for how one earthquake can influence events in other zones.”
High on the list of areas ripe for a great quake is Cascadia, the Pacific Northwest, where the risk for great quakes had long been under appreciated. Evidence began surfacing about 20 years ago that there had been a great quake in the region in the year 1700. Since then the view of the great quake risk in Cascadia has shifted dramatically.
“We don’t know many details about what happened in 1700,” said Lay. There were no instruments back then to observe and record it. And so the best way to try and understand the danger and what could happen in Cascadia is to study the recent events elsewhere.
Over the last decade Lay and his colleagues have been able to gather fine details about these giant earthquakes using data from an expanded global networks of seismometers, GPS stations, tsunami gauges, and new satellite imaging capabilities such as GRACE, InSAR, and LandSAT interferometry. Among the broader conclusions they have come to is that great quakes are very complicated and idiosyncratic. Lay will be presenting some of those idiosyncrasies at the meeting of the Geological Society of America in Vancouver on Oct. 21.
“What we’ve seen is that we can have multiple faults activated,” said Lay. “We’ve seen it off Sumatra and off Japan. Once earthquakes get going they can activate faulting in areas that were thought not physically feasible.”
The great Sumatra-Andaman earthquake of Dec. 26, 2004, for instance, unzipped a 1,300 kilometer long segment of the subduction zone and unleashed one of history’s most destructive, deadly tsunamis. Much of the rupture was along a region with very limited plate convergence. In Japan, the Kuril Islands, and the Solomon Islands, great mega-thrust ruptures have ruptured portions of the subduction zones that were thought too warm or weak to experience earthquakes.
“These earthquakes ruptured right through areas that had been considered to have low risk,” said Lay. “We thought that would not happen. But it did, so we have to adjust our understanding.”
Perhaps the best recent analogy to Cascadia is off the coast of Iquique, Chile, said Lay. There had been a great quake in 1877, and a conspicuous gap in quakes ever since. Like the 1700 Cascadia earthquake, there is little data for the 1877 event, which killed more than 2,500 people. In both subduction zones, the converging plates are thought to be accumulating strain which could be released in a very large and violent rupture. On April 1 of this year, some of that strain was released offshore of Iquique. There was a Mw8.1 rupture in the northern portion of the seismic gap. But it involved slip over less than 20 percent of the region that seismologists believe to have accumulated strain since 1877.
“We have no idea why only a portion of the 1877 zone ruptured,” said Lay. “But clearly, 80 percent of that zone is still unruptured. We don’t have a good basis for assessment of how the rest will fail. It’s the same for Cascadia. We don’t know if it always goes all at once or sometimes in sequences of smaller events, with alternating pattern. It is prudent to prepare for the worst case of failure of the entire region in a single event, but it may not happen that way every time.”
What is certain is that studying these recent big earthquakes has given geophysicists the best information ever about how they work and point to new ways to begin understanding what could be in Cascadia’s future.
More information:
A GLOBAL SURGE OF GREAT EARTHQUAKES FROM 2004-2014 AND IMPLICATIONS FOR CASCADIA
Abstract: gsa.confex.com/gsa/2014AM/webp… ram/Paper242140.html
Session No. 178. P4. Great Earthquakes, the Cascadia Subduction Zone, and Society I
Note : The above story is based on materials provided by Geological Society of America
Photos and drawings of inclusions in Canadian Cretaceous amber from Grassy Lake amber, a 78-79 million year old amber in the Late Cretaceous of southern Alberta. Credit: University of Alberta Strickland Entomology Museum specimen, R.C. McKellar; Chronomyrmex ant Grassy Lake amber, UASM specimen photo; Chronomyrmex ant Grassy Lake amber, UASM specimen drawing
Ryan McKellar’s research sounds like it was plucked from Jurassic Park: he studies pieces of amber found buried with dinosaur skeletons. But rather than re-creating dinosaurs, McKellar uses the tiny pieces of fossilized tree resin to study the world in which the now-extinct behemoths lived.
New techniques for investigating very tiny pieces of fragile amber buried in dinosaur bonebeds could close the gaps in knowledge about the ecology of the dinosaurs, said McKellar, who is a research scientist at the Royal Saskatchewan Museum in Saskatchewan, Canada.
“Basically it puts a backdrop to these dinosaur digs, it tells us a bit about the habitat,” said McKellar. The amber can show what kinds of plants were abundant, and what the atmosphere was like at the time the amber was formed, he explained. Scientists can then put together details regarding what kind of habitat the dinosaur lived in and how the bonebed formed.
The preliminary findings about dinosaur ecology, habitat, and other results from four different fossil deposits from the Late Cretaceous in Alberta and Saskatchewan, Canada, will be presented on Monday, October 20 at the Geological Society of America Annual Meeting in Vancouver, Canada.
“Just a few of these little pieces among the bones can show a lot of information,” McKellar said.
The type of amber that the scientists work with is not like the jewelry grade variety that can be made into a necklace or earrings.
“This type of amber hasn’t been pursued in the past. It is like working with a shattered candy cane,” he said. It is called friable amber, which is crumbly and fragile.
McKellar and his colleagues work with very small pieces of amber, just millimeters wide. But even samples at such a small scale can hold enormous clues to the past.
Before it hardened into amber, the sticky tree resin would often collect animal and plant material, like leaves and feathers. Scientists call these contents “inclusions,” which they study along with the surrounding amber, to look at environmental conditions, surrounding water sources, temperature, and even oxygen levels in the ancient environment.
Insects can also be included in the amber, which can be even more helpful to scientists. One example is the discovery of an aphid, stuck directly to a duck-billed dinosaur with some amber. With a find like this, scientists can track insect evolution, find their modern relatives, and see how they might have interacted with dinosaurs, said McKellar.
“When you get insects, it is like frosting on the cake — you can really round out the view of the ecosystem.”
Improvements in processing friable amber have made this research possible. Instead of the past technique of screening amber in a glycerin bath, the scientists reduce crumbling by vacuum-injecting the amber with epoxy, said McKellar.
Friable amber is widespread across the North American Continent in association with coals, and in the uncovered bonebeds, which means this area of research has expanded with the new techniques. It means scientists can sample at a finer scale, and still close some gaps in the past, especially regarding insect evolution, said McKellar.
Some of the early results of this method will be presented from amber pieces found with the skeleton of ‘Scotty’ the Tyrannosaurus rex, in Saskatchewan, Canada. McKellar will also be including case studies from three other bonebeds: the Danek Bonebed near Edmonton, Alberta; Dinosaur Provincial Park, Alberta; and the Pipestone Creek Pachyrhinosaurus Bonebed near Grande Prairie, Alberta.
Note : The above story is based on materials provided by Geological Society of America.
(L-R) Dr Giles Henry (University of Montpellier, France), Prof Doug Schmitt (University of Alberta, Canada), Dr Bernard Celerier (CNRS, France), and Loren Mathewson (MSc student from University of Otago) eagerly watch data being sent from instruments inside the Alpine Fault borehole. Credit: Virginia Toy
The multi-national Alpine Fault drilling project has moved to a new phase with a new drilling rig positioned over the borehole to take the probe to its target depth of 1.3kmIn the initial part of the project, the New Zealand-led team drilled through 240m of gravel-laden sediments in the Whataroa Valley, north of Franz Josef Glacier, and hit schist bedrock a few days ago.
They have now installed different drilling equipment above the borehole specially designed to penetrate the hard schist bedrock. All going well, the drill bit should intersect the fault at about 1000m depth in mid-November.
In preparation for the deep drilling phase, the scientists have placed concentric steel casings of 38cm, 30cm and 24cm diameter respectively through the sediments and into the bedrock to a depth of 270m. This forms a stable platform from which to drill deeper.
Although it less than a quarter of the way to its target depth, the borehole is already the deepest probe into the Alpine Fault yet attempted.
The project is being jointly led by GNS Science, Victoria University of Wellington, and the University of Otago and is funded mainly by the International Continental Scientific Drilling Program, the Marsden Fund of the Royal Society of New Zealand, and the participating scientists’ own organisations. It involves scientists from other New Zealand organisations and from more than a dozen other countries.
According to project co-leader Virginia Toy, of the University of Otago, the drilling has already yielded intriguing measurements of temperature and fluid.
“We have discovered that temperatures increase quite rapidly with depth, which tells us a lot about how fluids that once fell on the Southern Alps as rain circulate and warm up next to the Alpine Fault,” Dr Toy said.
“These measurements are important scientific findings in their own right and also allow us to predict what we will encounter as we drill deeper.”
Another project co-leader, John Townend of Victoria University of Wellington, said the project was important for New Zealand and for the international community.
“This work is important to New Zealand because it will provide the scientific data required to improve our understanding of the largest seismic hazard in the South Island,” said Associate Professor Townend.
“It’s also very important to the international scientific community in terms of understanding how large faults work mechanically, which is why so many scientists from around the world are working with us to extract maximum information from the borehole.”
Dr Bernard Célerier, a senior researcher at the National Center for Scientific Research in France and member of the group making geophysical measurements in the borehole commented that “This is a great opportunity for us to work closely with New Zealand researchers and colleagues from other countries to understand fundamental scientific problems of great relevance to society.”
His colleague Doug Schmitt of the University of Alberta in Canada is coordinating measurements of the rocks’ hydraulic properties, which govern the flow of fluids, said the project provided an opportunity to study many different aspects of the Alpine Fault’s internal structure using different methods. “This makes it a really important study,” Prof Schmitt said.
The third project co-leader Rupert Sutherland, of GNS Science, emphasised the multidisciplinary nature of the research.
“Our goal is to make important geological, geophysical, and geochemical measurements at all depths in the borehole to provide the greatest insight into the fault zone’s current state and what this implies for future earthquakes,” Dr Sutherland said.
In parallel with the drilling operations, the science team has set up a sophisticated field laboratory for processing and analysing rock and fluid samples and digital data from the borehole.
The laboratory equipment includes a mass spectrometer and gas chromatograph used to provide continuous measurements of gas chemistry and a core scanner that produces high-resolution images of core samples.
There is even an on-site facility to make microscopic slides of the rocks gathered within only a few hours of them having been ground up by the drill bit hundreds of metres below the surface.
The 60-strong scientific team assembled in Whataroa includes many experienced researchers as well as university students and up-and-coming researchers.
“The training I’m getting in new methods and the cool scientists I am meeting have already made this a fantastic trip,” said Katrina Sauer, a PhD student from California now working at the University of Otago.
Note : The above story is based on materials provided by University of Otago
Published on 14 September in Nature Geoscience, the study conducted by researchers from several institutes, including IFREMER (French Research Institute for Exploitation of the Sea), CNRS and IFSTTAR, offers the first theoretical model that, based on fluid-related processes, explains the seismic precursors of an underwater earthquake. Using quantitative measurements, this innovative model established a link between observed precursors and the mainshock of an earthquake. The results open a promising avenue of research for guiding future investigations on detecting earthquakes before they strike.
The data used to construct the model presented in the article were collected from subsea observatories* deployed in the North-East Pacific fracture zones.
The researchers showed that the properties of the fluids that circulate in submarine fault zones change over time, during what is called the “seismic cycle”. This term describes the cycle during which strain accumulates along a fault until it exceeds the frictional forces that prevent the fault from slipping. An earthquake results at the moment of rupture, due to the sudden release of built-up strain. A new cycle begins with strain accumulating and continues until the next rupture occurs along the fault…
Due to their proximity to mid-ocean ridges, the fluids that circulate in the faults undergo tremendous pressure and extremely high temperatures. These fluids can reach the supercritical state. The physical properties of supercritical fluids (density, viscosity, diffusivity) are intermediate to those of liquids and gases.
The compressibility of supercritical fluid varies greatly with pressure, and, according to the study’s analysis, this change in compressibility may trigger an earthquake, occurring after a short period of foreshocks.
Seismic precursors
Seismic precursors are the early warning signs before an earthquake strikes. Many different types of earthquake precursors have been studied by the scientific community: ground movements, seismic signals, fluid or gas emissions, electrical signals, thermal signals, animal behaviour, etc.
For an event as large as an earthquake, which releases a considerable amount of energy, there must be a preparatory phase. This problem in predicting earthquakes does not lie in the absence of precursors (hindsight observations are numerous), but in the capacity to detect these forerunners before the mainshock.
The results of the model can help guide future research in the detection of seismic precursors with, ultimately, potential applications for earthquake prediction. Supercritical fluids require very specific conditions; they are also encountered on land in hydrothermal and volcanic areas, such as Iceland.
Details of the model
Under the effect of tectonic forces, two antagonistic effects are usually in play near transform faults. First, increasing shear stress tends to break rocks and weaken resistance in the transform fault. Second, decreasing pressure of the fluid contained in the fault results in an increase in the volume of the pore space between rock beds. This effect acts as a stabilising suction cup, counterbalancing the ‘weakening’ in the rock bed and delaying the triggering of an earthquake.
The efficiency of this counterbalancing mechanism depends on fluid compressibility. It is highest in the presence of fluids in the liquid state, whose low compressibility causes a dramatic decrease in fluid pressure in response to small increases in volume. Conversely, for gas-type fluids, which are highly compressible, the suction cup effect is nearly inexistent.
When a change in the ‘liquid-gas’ state of the fluid occurs during a fault slip, the counterbalancing mechanism fails, allowing a major shock to be triggered. This transition occurs over several days and has numerous signs, including many small foreshocks.
*Subsea observatories are comparable to a laboratory on the seafloor. Equipped with a series of instruments, they record many types of data that can be used to study the geophysical events that occur in the ocean.
Note : The above story is based on materials provided by Institut français de recherche pour l’exploitation de la mer (Ifremer).
Hawaii’s evacuation maps are based in part on the 1946 tsunami, the most destructive tsunami in Hawaii’s recent history. But new research shows that mammoth tsunamis, many times the size of the 1946 event, have struck the island in the past, and may again in the future. Credit: USGS
A mass of marine debris discovered in a giant sinkhole in the Hawaiian islands provides evidence that at least one mammoth tsunami, larger than any in Hawaii’s recorded history, has struck the islands, and that a similar disaster could happen again, new research finds. Scientists are reporting that a wall of water up to nine meters (30 feet) high surged onto Hawaiian shores about 500 years ago. A 9.0-magnitude earthquake off the coast of the Aleutian Islands triggered the mighty wave, which left behind up to nine shipping containers worth of ocean sediment in a sinkhole on the island of Kauai.
The tsunami was at least three times the size of a 1946 tsunami that was the most destructive in Hawaii’s recent history, according to the new study that examined deposits believed to have come from the extreme event and used models to show how it might have occurred. Tsunamis of this magnitude are rare events. An earthquake in the eastern Aleutian Trench big enough to generate a massive tsunami like the one in the study is expected to occur once every thousand years, meaning that there is a 0.1 percent chance of it happening in any given year – the same probability as the 2011 Tohoku earthquake that struck Japan, according to Gerald Fryer, a geophysicist at the Pacific Tsunami Warning Center in Ewa Beach, Hawaii.
Nevertheless, the new research has prompted Honolulu officials to revise their tsunami evacuation maps to account for the possibility of an extreme tsunami hitting the county of nearly 1 million people. The new maps would more than double the area of evacuation in some locations, according to Fryer.
“You’re going to have great earthquakes on planet Earth, and you’re going to have great tsunamis,” said Rhett Butler, a geophysicist at the University of Hawaii at Manoa and lead author of the new study published online in Geophysical Research Letters, a journal of the American Geophysical Union. “People have to at least appreciate that the possibility is there.”
Hawaiians have told stories about colossal tsunamis hitting the islands for generations, but possible evidence of these massive waves was only first detected in the late 1990s when David Burney, a paleoecologist at the National Tropical Botanical Garden in Kalaheo, was excavating the Makauwahi sinkhole, a collapsed limestone cave on the south shore of Kauai.
Two meters (six and a half feet) below the surface he encountered a layer of sediment marked by coral fragments, mollusk shells and coarse beach sand that could only have come from the sea. But the mouth of the sinkhole was separated from the shore by 100 meters (328 feet) of land and seven-meter (23-foot) high walls. Burney speculated that the deposit could have been left by a massive tsunami, but he was unable to verify the claim.
The deposits remained a mystery until the Tohoku earthquake hit Japan in 2011. It caused water to surge inland like a rapidly rising tide, reaching heights up to 39 meters (128 feet) above the normal sea level. After that tsunami deluged the island nation, scientists began to question Hawaii’s current tsunami evacuation maps. The maps are based largely upon the 1946 tsunami, which followed a magnitude 8.6 earthquake in the Aleutian Islands and caused water to rise only two and a half meters (8 feet) up the side of the Makauwahi sinkhole.
“[The Japan earthquake] was bigger than almost any seismologist thought possible,” said Butler. “Seeing [on live TV] the devastation it caused, I began to wonder, did we get it right in Hawaii? Are our evacuation zones the correct size?”
To find out, the study’s authors used a wave model to predict how a tsunami would flood the Kauai coastline. They simulated earthquakes with magnitudes between 9.0 and 9.6 originating at different locations along the Aleutian-Alaska subduction zone, a 3,400-kilometer (2,113-mile) long ocean trench stretching along the southern coast of Alaska and the Aleutian Islands where the Pacific tectonic plate is slipping under the North American plate.
The researchers found that the unique geometry of the eastern Aleutians would direct the largest post-earthquake tsunami energy directly toward the Hawaiian Islands. Inundation models showed that an earthquake with a magnitude greater than 9.0 in just the right spot could produce water levels on the shore that reached eight to nine meters (26 to 30 feet) high, easily overtopping the Makauwahi sinkhole wall where the ocean deposits were found.
The authors used radiocarbon dated marine deposits from Sedanka Island off the coast of Alaska and along the west coasts of Canada and the United States that date back to the same time period as the Makauwahi deposit to show that all three sediments could have come from the same tsunami and provide some evidence that the event occurred, according to the study.
“[The authors] stitched together geological evidence, anthropological information as well as geophysical modeling to put together this story that is tantalizing for a geologist but it’s frightening for people in Hawaii,” said Robert Witter, a geologist at the U.S. Geological Survey in Anchorage, Alaska who was not involved in the study.
According to Witter, it is possible that a massive tsunami hit Hawaii hundreds of years ago, based on the deposits found in the Kauai sinkhole, but he said it is difficult to determine if all three locations experienced the same event based on radiocarbon dating alone.
Radiocarbon dating only gives scientists a rough estimate of the age of a deposit, he said. All three locations offer evidence of a great tsunami occurring between 350 and 575 years ago, but it is hard to know if it was the same tsunami or ones that occurred hundreds of years apart.
“An important next thing to do is to look for evidence for tsunamis elsewhere in the Hawaiian island chain,” said Witter.
Fryer, of the Pacific Tsunami Warning Center, is confident that more evidence of the massive tsunami will be found, confirming that events of this magnitude have rocked the island chain in the not-so-distant past.
“I’ve seen the deposit,” said Fryer, who was not involved in the study. “I’m absolutely convinced it’s a tsunami, and it had to be a monster tsunami.”
Fryer is so convinced that he has worked with the city and county of Honolulu to update their tsunami evacuation maps to include the possibility of a massive tsunami the size of the one detailed in the new study hitting the islands. The county hopes to have the new maps distributed to residents by the end of the year, he said.
“We prepared ourselves for the worst tsunami that’s likely to happen in one hundred years,” Fryer said of the current tsunami evacuation maps based on the 1946 event. “What hit Japan was a thousand-year event … and this scenario [in the eastern Aleutians] is a thousand year event.”
Artist’s impression of the first act of copulation in our distant ancestors. Credit: Image courtesy of Flinders University
A profound new discovery announced in Nature today by palaeontologist, Flinders University Professor John Long, reveals how the intimate act of sexual intercourse first evolved in our deep distant ancestors.
In one of the biggest discoveries in the evolutionary history of sexual reproduction, Professor Long has found that internal fertilisation and copulation appeared in ancient armoured fishes, called placoderms, about 385 million years ago in what is now Scotland.
Placoderms, the most primitive jawed vertebrates, are the earliest vertebrate ancestors of humans.
Published in Nature, the discovery shows that male fossils of the Microbrachius dicki, which belong to the antiarch group of placoderms, developed bony L-shaped genital limbs called claspers to transfer sperm to females; and females developed small paired bones to lock the male organs in place for mating.
Measuring about 8cm long, Microbrachius lived in ancient lake habitats in Scotland, as well as parts of Estonia and China.
As the paper’s lead author, Professor Long, who is the Strategic Professor in Palaeontology at Flinders University in South Australia, discovered the ancient fishes mating abilities when he stumbled across a single fossil bone in the collections of the University of Technology in Tallinn, Estonia, last year.
The fossils, he said, symbolise the most primitive known vertebrate sexual organ ever found, demonstrating the first use of internal fertilisation and copulation as a reproductive strategy known in the fossil record.
“Microbrachius means little arms but scientists have been baffled for centuries by what these bony paired arms were actually there for. We’ve solved this great mystery because they were there for mating, so that the male could position his claspers into the female genital area,” Professor Long said.
“It was previously thought that reproduction spawned externally in water, and much later down the track in the history of vertebrate evolution,” he said.
“Our earlier discoveries published in Nature in 2008 and 2009 of live birth and copulation in placoderms concerned more advanced placoderm groups. Our new discovery now pushes the origin of copulation back even further down the evolutionary ladder, to the most basal of all jawed animals.
“Basically it’s the first branch off the evolutionary tree where these reproductive strategies started.”
In one of the more bizarre findings of his research, Professor Long said the fishes probably copulated from a sideways position with their bony jointed arms locked together.
“This enabled the males to manoeuvre their genital organs into the right position for mating.
“With their arms interlocked, these fish looked more like they are square dancing the do-se-do rather than mating.”
Flinders Postdoctoral Research Fellow Dr Brian Choo, a co-author on the paper, said the discovery signifies the first time in evolutionary history that males and females showed distinct differences in their physical appearance.
“Until this point in evolution, the skeletons of jawed vertebrates couldn’t be distinguished because males and females had the same skeletal structures,” Dr Choo said.
“This is the first time in vertebrate evolution that males and females developed separate reproductive structures, with males developing claspers, and females developing fixed plates to lock the claspers in for mating,” he said.
The discovery highlights the importance of placoderms in the evolution of vertebrate animals, including humans, Professor Long said.
“Placoderms were once thought to be a dead-end group with no live relatives but recent studies show that our own evolution is deeply rooted in placoderms, and that many of the features we have, such as jaws, teeth and paired limbs, first originated with this group of fishes.
“Now, we reveal they gave us the intimate act of sexual intercourse as well.”
Dr Matt Friedman, a palaeobiologist from the University of Oxford, UK, described the discovery as “nothing short of remarkable.”
“Claspers in these fishes demand one of two alternative, but equally provocative, scenarios: either an unprecedented loss of internal fertilisation in vertebrates, or the coherence of the armoured placoderms as a single branch in the tree of life,” Dr Friedman, who was not involved in the study, said.
“Both conclusions fly in the face of received wisdom, and suggest that there is still much to discover about this critical episode in our own extended evolutionary history.”
The research involved a team of collaborators from Australia, Estonia, the UK, Sweden and China, who scrutinised a vast number of fossil specimens held in museum collections across the world.
Fossil specimens of male and female Microbrachius fossils will be placed on public display in the foyer of the South Australian Museum from today (October 20).
A Flinders Creations video documenting the discovery, as well as an animation portraying the earliest known copulation.
Video:
Note : The above story is based on materials provided by Flinders University.
A blend of photos and technology takes a new twist on studying cliff landscapes and how they were formed. Dylan Ward, a University of Cincinnati assistant professor of geology, will present a case study on this unique technology application at The Geological Society of America’s Annual Meeting & Exposition. The meeting takes place Oct. 19-22, in Vancouver.
Ward is using a method called Structure-From-Motion Photogrammetry – computational photo image processing techniques – to study the formation of cliff landscapes in Colorado and Utah and to understand how the layered rock formations in the cliffs are affected by erosion.
To get an idea of these cliff formations, think of one of the nation’s most spectacular tourist attractions, the Grand Canyon.
“The Colorado plateau, for example, has areas with a very simple, sandstone-over-shale layered stratigraphy. We’re examining how the debris and sediment off that sandstone ends up down in the stream channels on the shale, and affects the erosion by those streams,” explains Ward. “The river cuts down through the rock, creating the cliffs. The cliffs walk back by erosion, so there’s this spectacular staircase of stratigraphy that owes its existence and form to that general process.”
Ward’s research takes a new approach to documenting the topography in very high resolution, using a new method of photogrammetry – measurement in 3-D, based on Dylan Ward, a UC assistant professor of geology, is studying the formation of cliff landscapes such as this in Colorado and Utah.
stereo photographs. “First, we use a digital camera to take photos of the landscape from different angles. Then, we use a sophisticated imaging processing program than can take that set of photos and find the common points between the photographs. From there, we can build a 3-D computer model of that landscape. Months of fieldwork, in comparison, would only produce a fraction of the data that we produce in the computer model,” says Ward.
Ward says that ultimately, examining this piece of the puzzle will give researchers an idea as to how the broader U.S. landscape was formed.
Note : The above story is based on materials provided by University of Cincinnati
A University of Cincinnati research project is taking a groundbreaking approach to monitoring groundwater resources near fracking sites in Ohio. Claire Botner, a UC graduate student in geology, will outline the project at The Geological Society of America’s Annual Meeting & Exposition. The meeting takes place Oct. 19-22, in Vancouver.
Botner’s research is part of UC Groundwater Research of Ohio (GRO), a collaborative research project out of UC to examine the effects of fracking (hydraulic fracturing) on groundwater in the Utica Shale region of eastern Ohio. First launched in Carroll County in 2012, the GRO team of researchers is examining methane levels and origins of methane in private wells and springs before, during and after the onset of fracking. The team travels to the region to take water samples four times a year.
Amy Townsend-Small, the lead researcher for GRO and a UC assistant professor of geology, says the UC study is unique in comparison with studies on water wells in other shale-rich areas of the U.S. where fracking is taking place – such as the Marcellus Shale region of Pennsylvania. Townsend-Small says water samples finding natural gas-derived methane in wells near Pennsylvania fracking sites were taken only after fracking had occurred, so methane levels in those wells were not documented prior to or during fracking in Pennsylvania.
Hydraulic fracturing, or fracking, involves using millions of gallons of water mixed with sand and chemicals to break up organic-rich shale to release natural gas resources. Proponents say the practice promises a future in lower energy prices, an increase in domestic jobs and less dependence on foreign oil from unstable overseas governments. Opponents raise concerns about increasing methane gas levels (a powerful greenhouse gas) and other contamination involving the spillover of fracking wastewater in the groundwater of shale-rich regions.
“The only way people with private groundwater will know whether or not their water is affected by fracking is through regular monitoring,” says Townsend-Small.
The Ohio samples are being analyzed by UC researchers for concentrations of methane as well as other hydrocarbons and salt, which is pulled up in the fracking water mixture from the shales. The shales are ancient ocean sediments.
Botner’s study involves testing on 22 private wells in Carroll County between November 2012 and last May. The first fracking permits were issued in the region in 2011. So far, results indicate that any methane readings in groundwater wells came from organic matter. In less than a handful of cases, the natural methane levels were relatively high, above 10 milligrams per liter. However, most of the wells carried low levels of methane.
The UC sampling has now been expanded into Columbiana, Harrison, Stark and Belmont counties in Ohio. Researchers then review data on private drinking water wells with the homeowners. “We’re working on interacting with these communities and educating them about fracking as well as gathering scientific data, which is lacking on a very sensitive issue,” says Botner. “It can also be reassuring to receive data on their water supplies from an objective, university resource.”
The team also is seeking additional funding to begin monitoring groundwater wells near wastewater injection wells, where fracking brine is deposited after the wells are drilled.
Funding for Botner’s research to be presented at the GSA meeting is supported by a grant from the Missouri-based Deer Creek Foundation.
Note : The above story is based on materials provided by University of Cincinnati
Naturally occurring asbestos minerals may be more widespread than previously thought, with newly discovered sources now identified within the Las Vegas metropolitan area. The asbestos-rich areas are in locations not previously considered to be at risk, according to new report that will be presented at the Annual Meeting of the Geological Society of America (GSA) in Vancouver, Canada, on Sunday, 20 October.
“These minerals were found where one wouldn’t expect or think to look,” said Rodney Metcalf, associate professor of geology at the University of Nevada, Las Vegas, and co-researcher of the study. The naturally occurring asbestos was found in Boulder City, Nevada, in the path of a construction zone to build a multi-million dollar highway called the Boulder City Bypass, the first stage of an I-11 corridor planned between Las Vegas and Arizona.
Asbestos is a family of fibrous minerals which are known to cause lung cancer, mesothelioma, and other serious respiratory related illnesses when the fibers are inhaled. The GSA presentation will focus on the discovery of types of asbestos that geologists call fibrous iron sodium amphiboles and fibrous actinolite in Clark County, Nevada, and the geological settings that caused the unusual asbestos formation, said Metcalf.
“[Asbestos] is like a precious metal deposit, it forms at the confluence of several geologic features, which vary at each location,” said Metcalf.
In this case, it was a geological confluence of groundwater interacting with rock salt and a cooling magma body deep below earth’s surface to form the fibers and create this type of asbestos, said Brenda Buck, a professor of geology at UNLV and co-researcher of the study.
Later the rock was brought to the surface where it now exposed to rain and wind that can disperse it. This is the first discovery of asbestos in this kind of geological setting and it suggests the minerals could occur in other similar settings around the globe, said Buck, who has a background in medical geology.
Many regulations have been created to protect people from exposure to mined and refined asbestos, like fibrous actinolite, which the scientists discovered. But some naturally occurring asbestos is not regulated or labeled toxic under federal law, though they can be just as dangerous or even more toxic to humans, said Buck.
Naturally occurring asbestos can also be harmful and difficult to control, especially when it becomes dust and can be transported on the wind.
The research is being performed while the construction for a Boulder City bypass has been delayed due to concerns about the hazard of the naturally occurring asbestos. Boulder City has about 15,000 residents, and is about 32 kilometers (20 miles) from the Las Vegas metropolitan area, home to over 1.9 million people.
Scientists are still researching the amount of asbestos that is in the soil in the construction area, its toxicity to humans, and how far it can be transported by wind.
The new research Metcalf will be presenting could help scientists locate more formations of naturally occurring asbestos in areas that were not previously considered, he said.
“This means that there could be a lot of areas in the world that could have asbestos that we don’t know about. So there are people that are being exposed that have no idea,” said Buck.
The abstract can be found online at: https://gsa.confex.com/gsa/2014AM/webprogram/Paper250494.html
Note : The above story is based on materials provided by Geological Society of America, The.
Dr. Rhodri Davies in the Raijin Supercomputer at The Australian National University. Credit: Stuart Hay, ANU
Scientists have solved a long-standing mystery surrounding Australia’s only active volcanic area, in the country’s southeast.
The research explains a volcanic region that has seen more than 400 volcanic events in the last four million years. The 500 kilometre long region stretches from Melbourne to the South Australian town of Mount Gambier, which surrounds a dormant volcano that last erupted only 5,000 years ago.
“Volcanoes in this region of Australia are generated by a very different process to most of Earth’s volcanoes, which occur on the edges of tectonic plates, such as the Pacific Rim of Fire”, says lead researcher Dr Rhodri Davies, from the Research School of Earth Sciences.
“We have determined that the volcanism arises from a unique interaction between local variations in the continent’s thickness, which we were able to map for the first time, and its movement, at seven centimetres a year northwards towards New Guinea and Indonesia.
The volcanic area is comparatively shallow, less than 200 kilometres deep, in an area where a 2.5 billion year-old part of the continent meets a thinner, younger section, formed in the past 500 million years or so.
These variations in thickness drive currents within the underlying mantle, which draw heat from deeper up to the surface.
The researchers used state-of-the-art techniques to model these currents on the NCI Supercomputer, Raijin, using more than one million CPU hours.
“This boundary runs the length of eastern Australia, but our computer model demonstrates, for the first time, how Australia’s northward drift results in an isolated hotspot in this region,” Dr Davies said.
Dr Davies will now apply his research technique to other volcanic mysteries around the globe.
“There are around 50 other similarly isolated volcanic regions around the world, several of which we may now be able to explain,” he said.
It is difficult to predict where or when future eruptions might occur, Dr Davies said.
“There hasn’t been an eruption in 5,000 years, so there is no need to panic. However, the region is still active and we can’t rule out any eruptions in the future.”
Note : The above story is based on materials provided by Australian National University
Assistant Professor of Earth Sciences Zunli Lu was among the researchers to release these findings. Credit: Syracuse University
Researchers in Syracuse University’s College of Arts and Sciences are pairing chemical analyses with micropaleontology — the study of tiny fossilized organisms — to better understand how global marine life was affected by a rapid warming event more than 55 million years ago.
Their findings are the subject of an article in the journal Paleoceanography.
“Global warming impacts marine life in complex ways, of which the loss of dissolved oxygen [a condition known as hypoxia] is a growing concern” says Zunli Lu, assistant professor of Earth sciences and a member of Syracuse’s Water Science and Engineering Initiative. “Moreover, it’s difficult to predict future deoxygenation that is induced by carbon emissions, without a good understanding of our geologic past.”
Lu says this type of deoxygenation leads to larger and thicker oxygen minimum zones (OMZs) in the world’s oceans. An OMZ is the layer of water in an ocean where oxygen saturation is at its lowest.
Much of Lu’s work revolves around the Paleocene-Eocene Thermal Maximum (PETM), a well-studied analogue for modern climate warming. Documenting the expansion of OMZs during the PETM is difficult because of the lack of a sensitive, widely applicable indicator of dissolved oxygen.
To address the problem, Lu and his colleagues have begun working with iodate, a type of iodine that exists only in oxygenated waters. By analyzing the iodine-to-calcium ratios in microfossils, they are able to estimate the oxygen levels of ambient seawater, where microorganisms once lived.
Fossil skeletons of a group of protists known as foraminiferas have long been used for paleo-environmental reconstructions. Developing an oxygenation proxy for foraminifera is important to Lu because it could enable him study the extent of OMZs “in 3-D,” since these popcorn-like organisms have been abundant in ancient and modern oceans.
“By comparing our fossil data with oxygen levels simulated in climate models, we think OMZs were much more prevalent 55 million years ago than they are today,” he says, adding that OMZs likely expanded during the PETM. “Deoxygenation, along with warming and acidification, had a dramatic effect on marine life during the PETM, prompting mass extinction on the seafloor.”
Lu thinks analytical facilities that combine climate modeling with micropaleontology will help scientists anticipate trends in ocean deoxygenation. Already, it’s been reported that modern-day OMZs, such as ones in the Eastern Pacific Ocean, are beginning to expand. “They’re natural laboratories for research,” he says, regarding the interactions between oceanic oxygen levels and climate changes.”
Note : The above story is based on materials provided by Syracuse University.
This phylogenetic tree illustrates the changes in geographic range of wing-propelled diving seabirds like the modern-day puffin and auk. Modern-day puffins and auks have long been recognized as environmental indicator species for ongoing faunal shifts, and fossil records now indicate that ancient relatives were similarly informative. Researchers have found that puffins and auks may have been at their most diverse and widespread levels during a relatively warm period of Earth’s history. The results also explain how past extinctions have shaped the geographic distribution and population size of existing species. Credit: Adam Smith
Modern-day puffins and auks have long been recognized as environmental indicator species for ongoing faunal shifts, and fossil records now indicate that ancient relatives were similarly informative. Researchers have found that puffins and auks may have been at their most diverse and widespread levels during a relatively warm period of Earth’s history. The results also explain how past extinctions have shaped the geographic distribution and population size of existing species.
Authors Adam Smith of the National Evolutionary Synthesis Center (NESCent) in Durham, N.C., and Julia Clarke of the University of Texas at Austin examined 28 extinct species in addition to 23 living species. Whereas previous research focused primarily on surviving members of the alcid family, this study was able to paint a more comprehensive picture of their evolution. The findings, which were just published online at the Journal of Avian Biology, support a connection between the diversification of wing-propelled diving seabirds and major climatic events. Such environmental conditions also appear to have influenced the physical traits observed in existing alcids like dovekies, murres, murrelets, puffins, auklets and auks.
The results indicate that the Pan-Alcidae clade, including all living auks and puffins as well as extinct species, first emerged about 35 million years ago. Through phylogenetic analyses of fossils and current species, the researchers were able to estimate “ghost lineages,” a method of approximating gaps in the fossil record. By using ghost lineages to extrapolate species diversity over time, the scientists found that pan-alcid species enjoyed the most variety and widespread ranges about 15 million years ago during a period that climate scientists refer to as the Middle Miocene Climatic Optimum.
The researchers found that the geographic distribution and population size of modern alcids are primarily the result of extinctions corresponding with climate and ocean shifts over the last 5 million years. As ocean circulation changed and water surface temperatures cooled dramatically throughout a series of ice ages, species diversity bottlenecked for both Atlantic and Pacific Ocean species. More than 50 percent of species went extinct at this time, which roughly coincided with changes in ocean basin circulation, such as the onset of Gulf Stream circulation. The results contextualize contemporary changes in geographic range and decreases in population sizes of seabirds due to global warming and overfishing.
Smith and Clarke also considered the evolution of wing-propelled diving — a rare behavior found in only one-half percent of all birds. Previously assumed to be a nascent feature of the earliest alcid species, underwater diving could have first arisen as an escape tactic rather than a feeding strategy, according to the study results. Relatives like seagulls and terns plunge from the air, whereas modern puffins and auks dive from a floating position. By reconstructing the ancestral diet, the authors found that early species most likely fed on vertebrates close to the surface; they hypothesize that alcids gradually began to dive deeper and hunt invertebrates such as crustaceans and shrimp, which are included in the diet of some modern species.
The study elucidates how extinct alcids were affected by climate change and other environmental pressures — an area that has been somewhat neglected. Smith and Clarke hope that the results will strengthen modern conservation efforts by lending context to the plight of their modern kin and other seabirds.
Note : The above story is based on materials provided by National Evolutionary Synthesis Center (NESCent).
Sumatra volcano Sinabung has been releasing hot ash and gravel in the past week. Credit: EPA/DEDY SAHPUTRA
Living alongside active volcanoes in places like Japan, the Philippines and especially Indonesia can be uncomfortable.
Around half a billion people in the world live near high-risk volcanic eruption areas. Of 829 volcanoes in the world, 129 of them, or around 15.6%, are located in Indonesia.
It’s scary to have to constantly wonder when an eruption will start or end. Just recently, the Sinabung volcano in Sumatra, Indonesia, has been coughing up hot ash. People living near the volcano are wondering every day when Sinabung will end its blasts.
Limited knowledge on historical eruptions from volcanoes such as Sinabung makes it difficult to precisely predict the next one.
Vulcanologist have attempted to predict eruptions by using a volcano’s “regularity” pattern.
Volcanoes usually release volcanic material over a certain range of time, with the volume of material released being relatively constant. When a volcanic eruption happens earlier than the average interval, in theory the volume it releases will be less than the regular volume. When it erupts beyond the time range, it will release more material.
It is not that easy, however, to predict Sinabung because it has been dormant for 400 years. Deleng Sinabung, as it is called by the local Karo people, is located north of the Toba Caldera in Karo regency, North Sumatra. Before recent eruptions that took 16 lives, the last eruption was in the 1600s. Long periods of dormancy makes people forget about the danger the volcano holds.
Due to Sinabung’s long slumber, there are few documents about the timing and volume of its eruptions. Indeed, before 2010, eruptions occurred rarely, with long periods in between. After 2010 they become fairly regular.
Sinabung erupted in 2010, 2013 and 2014. While this might reflect a real eruption frequency increase, such that Sinabung has entered a regime of higher activity, we cannot be sure since the earlier historical record is incomplete.
Assigning the Volcanic Explosivity Index (VEI) value of older eruptions is also difficult due to the lack of data. We also could not calculate precisely the ejected volume of older eruptions. After 400 years, there has been erosion of volcanic materials in the area.
Researchers observing the mountain since 2010 record the height of the eruption column reaching between 1.5 and 5 kilometres, with a volume of 10,000,000 cubic metres. This shows Sinabung has a VEI value between 2 and 3, with around one to three little eruptions every year. Let’s hope this would be Sinabung’s regularity pattern.
Researchers have applied this method of prediction with relative success. The average uncertainty level is less than 20%. This method works especially well for volcanoes with a VEI of more than 5. Researchers managed to predict accurately eruptions in Pinatubo in the Philippines in 1991 and in Raupehu in New Zealand in 1996.
Still, we need to stay alert. Sometimes volcanoes can erupt outside of this rhythm, without any precursor. Such is the case of the recent Ontake eruption in Gifu, Japan.
Deadly spectacle
In Indonesia people are attracted to live near these sleeping giants for the cool climate, clean water and beautiful views.
The land near volcanoes is very fertile. The time period between eruptions, which could go up to 100 years of more, decreases our alertness to disaster risks.
When volcanoes come to life, they may also bring death. They release volcanic ashes. These are soft particles with a diameter of more than 2mm. Gas thrust will launch the volcanic ashes into a convective ascent, creating an eruption column. The hot ash continues to climb until it reaches a level of neutral buoyancy, creating an umbrella of ash in the air.
Rocks bigger than 2mm diameter don’t usually climb up. Instead, they shoot out like ballistic bombs.
This is a fascinating spectacle that can turn deadly in a matter of seconds. Loss of pressure from the eruption column will send a pyroclastic flow down the slopes, destroying everything in its path. When this happens, areas close to the volcano should be evacuated.
People should also know how to deal with ash rain. Build-up of these ashes would later contribute to land fertility. But, when floating in the air, it could cause lung irritation.
Tips to cope with volcanic ashes
Reduce motor vehicle usage: Volcanic ashes can decrease the range of visibility, so if we need to use a vehicle we should drive it very slowly.
Reduce ash deposits inside the house: Close all the windows and doors to reduce the possibility of ashes entering. The longer and deeper we inhale, the deeper the ashes go into our lungs.
Protection: Provide glasses and masks. Use them immediately to reduce eye and lung irritation. The masks should be wet to maximise the filtering of the air.
Food and drink: It is usually safe to consume water and food after a light ash rain. You should wash the food and put it in a closed container before consumption. Stock up a week’s worth of drinking water.
Cleaning volcanic ashes: Dab water to clean the ashes. Cleaning when dry will make the ashes fly. Be careful when pouring water on rooftops while cleaning. Too much water will add weight and can cause the roof to collapse.
Tips for children’s protection: Children face the same dangers as other age groups. However, they have a higher risk because they are physically smaller. Psychologically, they are not equipped to make rational choices as adults. Exposure to small amounts of volcanic ashes is not harmful. But precautions should be taken.
Keep children inside
Advise them not to run around to avoid ashes entering their respiratory system
Use masks and glasses when taking refuge in a safe place
Prepare an adequate food supply
Try to make them feel comfortable and safe
Asks for medical assistance when symptoms of irritation occur.
Volcanologist Robert Decker wrote:
Volcanoes assail the senses. They are beautiful in repose and awesome in eruption;They hiss and roar; they smell of brimstone.Their heat warms, their fires consume; they are the homes of Gods and Goddesses,
He is right and there’s no other way but to learn to live with that.
Note : The above story is based on materials provided by The Conversation This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).The Conversation
Roots of the ancient mountain range, long since eroded, were found in Northeast Brazil. Credit: Carlos Ganade de Araujo
Scientists have found evidence for a huge mountain range that sustained an explosion of life on Earth 600 million years ago.
The mountain range was similar in scale to the Himalayas and spanned at least 2,500 kilometers of modern west Africa and northeast Brazil, which at that time were part of the supercontinent Gondwana.
“Just like the Himalayas, this range was eroded intensely because it was so huge. As the sediments washed into the oceans they provided the perfect nutrients for life to flourish,” said Professor Daniela Rubatto of the Research School of Earth Sciences at The Australian National University (ANU).
“Scientists have speculated that such a large mountain range must have been feeding the oceans because of the way life thrived and ocean chemistry changed at this time, and finally we have found it.”
The discovery is earliest evidence of Himalayan-scale mountains on Earth.
“Although the mountains have long since washed away, rocks from their roots told the story of the ancient mountain range’s grandeur,” said co-researcher Professor Joerg Hermann.
“The range was formed by two continents colliding. During this collision, rocks from the crust were pushed around 100 kilometers deep into the mantle, where the high temperatures and pressures formed new minerals.”
As the mountains eroded, the roots came back up to the surface, to be collected in Togo, Mali and northeast Brazil, by Brazilian co-researcher Carlos Ganade de Araujo, from the University of Sao Paulo and Geological Survey of Brazil.
Dr Ganade de Araujo recognized the samples were unique and brought the rocks to ANU where, using world-leading equipment, the research team accurately identified that the rocks were of similar age, and had been formed at similar, great depths.
The research team involved specialists from a range of different areas of Earth Science sharing their knowledge, said Professor Rubatto.
Video:
Note : The above story is based on materials provided by Australian National University.
The volcanic rocks of the 1.1 billion-year-old Midcontinent Rift play a prominent role in the natural beauty of Isle Royale National Park in Lake Superior. Credit: Image courtesy of Northwestern University
An international team of geologists has a new explanation for how the Midwest’s biggest geological feature — an ancient and giant 2,000-mile-long underground crack that starts in Lake Superior and runs south to Oklahoma and to Alabama — evolved.
Scientists from Northwestern University, the University of Illinois at Chicago (UIC), the University of Gottingen in Germany and the University of Oklahoma report that the 1.1 billion-year-old Midcontinent Rift is a geological hybrid, having formed in three stages: it started as an enormous narrow crack in the Earth’s crust; that space then filled with an unusually large amount of volcanic rock; and, finally, the igneous rocks were forced to the surface, forming the beautiful scenery seen today in the Lake Superior area of the Upper Midwest.
The rift produced some of the Midwest’s most interesting geology and scenery, but there has never been a good explanation for what caused it. Inspired by vacations to Lake Superior, Seth and Carol A. Stein, a husband-and-wife team from Northwestern and UIC, have been determined to learn more in recent years.
Their study, which utilized cutting-edge geologic software and seismic images of rock located below the Earth’s surface in areas of the rift, will be presented Oct. 20 at the Geological Society of America annual meeting in Vancouver.
“The Midcontinent Rift is a very strange beast,” said the study’s lead author, Carol Stein, professor of Earth and Environmental Sciences at UIC. “Rifts are long, narrow cracks splitting the Earth’s crust, with some volcanic rocks in them that rise to fill the cracks. Large igneous provinces, or LIPs, are huge pools of volcanic rocks poured out at the Earth’s surface. The Midcontinent Rift is both of these — like a hybrid animal.”
“Geologists call it a rift because it’s long and narrow,” explained Seth Stein, a co-author of the study, “but it’s got much more volcanic rock inside it than any other rift on a continent, so it’s also a LIP. We’ve been wondering for a long time how this could have happened.” He is the William Deering Professor of Geological Sciences at the Weinberg College of Arts and Sciences.
This question is one of those that EarthScope, a major National Science Foundation program involving geologists from across the U.S., seeks to answer. In this case, the team used images of the Earth at depth from seismic experiments across Lake Superior and EarthScope surveys of other parts of the Midcontinent Rift. The images show the rock layers at depth, much as X-ray photos show the bones in people’s bodies.
In reviewing the images, the researchers found the Midcontinent Rift appeared to evolve in three stages.
“First, the rocks were pulled apart, forming a rift valley,” Carol Stein said. “As the rift was pulling apart, magma flowed into the developing crack. After about 10 million years, the crack stopped growing, but more magma kept pouring out on top. Older magma layers sunk under the weight of new magma, so the hole kept deepening. Eventually the magma ran out, leaving a large igneous province — a 20-mile-thick pile of volcanic rocks. Millions of years later, the rift got squeezed as a new supercontinent reassembled, which made the Earth’s crust under the rift thicker.”
To test this idea, the Steins turned to Jonas Kley, professor of geology at Germany’s Gottingen University, their host during a research year in Germany sponsored by the Alexander von Humboldt Foundation.
Kley used software that allows geologic time to run backwards. “We start with the rocks as they are today,” Kley explained, “and then undo movement on faults and vertical movements. It’s like reconstructing a car crash. When we’re done we have a picture of what happened and when. This lets us test ideas and see if they work.”
Kley’s analysis showed that the three-stage history made sense — the Midcontinent Rift started as a rift and then evolved into a large igneous province. The last stage brought rocks in the Lake Superior area to the surface.
Other parts of the picture fit together nicely, the Steins said. David Hindle, also from Gottingen University, used a computer model to show that the rift’s shape seen in the seismic images results from the crust bending under weight of magma.
Randy Keller, a professor and director of the Oklahoma Geological Survey, found that the weight of the dense magma filling the rift explains the stronger pull of gravity measured above the rift. He points out that these variations in the gravity field are the major evidence used to map the extent of the rift.
“It’s funny,” Seth Stein mused. “Carol and I have been living in Chicago for more than 30 years. We often have gone up to Lake Superior for vacations but didn’t think much about the geology. It’s only in the past few years that we realized there’s a great story there and started working on it. There are many studies going on today, which will give more results in the next few years.”
The Steins now are working with other geologists to help park rangers and teachers tell this story to the public. For example, a good way to think about how rifts work is to observe what happens if you pull both ends of a Mars candy bar: the top chocolate layer breaks, and the inside stretches.
“Sometimes people think that exciting geology only happens in places like California,” Seth Stein said. “We hope results like this will encourage young Midwesterners to study geology and make even further advances.”
Note : The above story is based on materials provided by Northwestern University.
This map of the Samoan hotspot shows its division into three parallel volcanic lineaments. Credit: UCSB
A UC Santa Barbara geochemist studying Samoan volcanoes has found evidence of the planet’s early formation still trapped inside the Earth. Known as hotspots, volcanic island chains such as Samoa can ancient primordial signatures from the early solar system that have somehow survived billions of years.
Matthew Jackson, an associate professor in UCSB’s Department of Earth Science, and colleagues utilized high-precision lead and helium isotope measurements to unravel the chemical composition and geometry of the deep mantle plume feeding Samoa’s volcanoes. Their findings appear today in the journal Nature.
In most cases, volcanoes are located at the point where two tectonic plates meet, and are created when those plates collide or diverge. Hotspot volcanoes, however, are not located at plate boundaries but rather represent the anomalous melting in the interior of the plates.
Such intraplate volcanoes form above a plume-fed hotspot where the Earth’s mantle is melting. The plate moves over time — at approximately the rate human fingernails grow (3 inches a year) — and eventually the volcano moves off the hotspot and becomes extinct. Another volcano forms in its place over the hotspot and the process repeats itself until a string of volcanoes evolves.
“So you end up with this linear trend of age-progressive volcanoes,” Jackson said. “On the Pacific plate, the youngest is in the east and as you go to the west, the volcanoes are older and more deeply eroded. Hawaii has two linear trends of volcanoes — most underwater — which are parallel to each other. There’s a southern trend and a northern trend.”
Because the volcanic composition of parallel Hawaiian trends is fundamentally different, Jackson and his team decided to look for evidence of this in other hotspots. In Samoa, they found three volcanic trends exhibiting three different chemical configurations as well as a fourth group of a late-stage eruption on top of the third trend of volcanoes. These different groups exhibit distinct compositions.
“Our goal was to figure out how we could use this distribution of volcano compositions at the surface to reverse-engineer how these components are distributed inside this upwelling mantle plume at depth,” Jackson said.
Each of the four distinct geochemical compositions, or endmembers, that the scientists identified in Samoan lavas contained low Helium-3 (He-3) and Helium-4 (He-4) ratios. The surprising discovery was that they all exhibited evidence for mixing with a fifth, rare primordial component consisting of high levels of He-3 and He-4.
“We have really strong evidence that the bulk of the plume is made of the high Helium-3, -4 component,” Jackson said. “That tells us that most of this plume is primordial material and there are other materials hosted inside of this plume with low Helium-3, -4, and these are likely crustal materials sent into the mantle at ancient subduction zones.”
The unique isotopic topology revealed by the researchers’ analysis showed that the four low-helium endmembers do not mix efficiently with one another. However, each of them mixes with the high He-3 and He-4 component.
“This unique set of mixing relationships requires a specific geometry for the four geochemical flavors within the upwelling plume: They must be hosted within a matrix that is composed of the rare fifth component with high He-3,” Jackson explained. “This new constraint on plume structure has important implications for how deep mantle material is entrained in plumes, and it gives us the clearest picture yet for the chemical structure of an upwelling mantle plume.”
Co-authors of the paper include Stanley R. Hart, Jerzy S. Blusztajn and Mark D. Kurz of the Woods Hole Oceanographic Institution, Jasper G. Konter of the University of Hawaii and Kenneth A. Farley of the California Institute of Technology. This research was funded by the National Science Foundation.
Note : The above story is based on materials provided by University of California – Santa Barbara. The original article was written by Julie Cohen.
A 500-million-year-old fossil used by Australian researchers to make their discovery about vetulicolians. These marine creatures had a rod through their tail similar to a backbone, which places them as distant cousins of vertebrate animals. Credit: University of Adelaide/South Australian Museum
More than 100 years since they were first discovered, some of the world’s most bizarre fossils have been identified as distant relatives of humans, thanks to the work of University of Adelaide researchers.
The fossils belong to 500-million-year-old blind water creatures, known to scientists as “vetulicolians” (pronounced: ve-TOO-lee-coal-ee-ans).
Alien-like in appearance, these marine creatures were “filter-feeders” shaped like a figure eight. Their strange anatomy has meant that no one has been able to place them accurately on the tree of life, until now.
In a new paper published in BMC Evolutionary Biology, researchers at the University of Adelaide and the South Australian Museum argue for a change in the way these creatures are viewed, placing them with the same group that includes vertebrate animals, such as humans.
“Although not directly related to humans in the evolutionary line, we can confirm that these ancient water creatures are among our distant cousins,” says the lead author of the paper, Dr Diego Garcia-Bellido, ARC Future Fellow with the University’s Environment Institute.
“They are close relatives of vertebrates — animals with backbones, such as ourselves. Vetulicolians have a long tail supported by a stiff rod. This rod resembles a notochord, which is the precursor of the backbone and is unique to vertebrates and their relatives,” he says.
Although the first specimens were studied in 1911, it took until 1997 for the fossils to be described as a group on their own: the vetulicolians. These fossils have now been discovered in countries all across the globe, such as Canada, Greenland, China and Australia.
The latest insights into vetulicolians have come from new fossils discovered on Kangaroo Island off the coast of South Australia, which the researchers named Nesonektris (Greek for “Island Swimmer”).
“Vetulicolians are further evidence that life was very rich in diversity during the Cambrian period, in some aspects more than it is today, with many extra branches on the evolutionary tree,” Dr Diego Garcia-Bellido says. “They were simple yet successful creatures, large in number and in distribution across the globe, and one of the first representatives of our cousins, which include sea squirts and salps.”
The research involved collaboration between the University of Adelaide, South Australian Museum, University of South Australia, the Natural History Museum, London, and University of New England.
Note : The above story is based on materials provided by University of Adelaide.
(A) This is a photograph of fossil transformer in left view. (B) Photograph of fossil transformer in left view. (C) Box area in B in higher magnification, showing the radials. (D) Photograph and (E) drawing of the head and anterior part of the body of A. (F) Photograph and (G) drawing of the head and anterior part of the body of B. Credit: Proceedings of the National Academy of Sciences
Few people devote time to pondering the ancient origins of the eel-like lamprey, yet the evolutionary saga of the bloodsucker holds essential clues to the biological roots of humanity.
Today, the Proceedings of the National Academy of Sciences published a description of fossilized lamprey larvae that date back to the Lower Cretaceous — at least 125 million years ago.
They’re the oldest identified fossils displaying the creature in stages of pre-metamorphosis and metamorphosis.
“Among animals with backbones, everything, including us, evolved from jawless fishes,” said Desui Miao, University of Kansas Biodiversity Institute collection manager, who co-authored today’s PNAS paper. “To understand the whole arc of vertebrate evolution, we need to know these animals. The biology of the lamprey holds a molecular clock to date when many evolutionary events occurred.”
Miao said features of the human body come from the jawless fishes, such as the lamprey, a slowly evolving organism — often parasitic — which has inhabited Earth at least since the Devonian, about 400 million years ago.
“For example, a jawless fish such as a lamprey has seven pairs of gill arches, and the anterior pair of these gill arches evolved into our upper and lower jaws,” he said. “Our middle ear bones? They come from the same pair of gill arches.”
Indeed, lamprey evolution sheds light on the development of all animals with a backbone. Because of this, scientists have yearned to discover more history about the stages of the aquatic creature’s three-phased life cycle.
However, lamprey larvae are small and soft, thus seldom fossilized.
“They just don’t have hard parts,” Miao said. “Even fully developed fossil lampreys are rare because they lack skeletons. Most fossil fishes are bony fishes — fish we eat and leave bones on the plate. But lampreys don’t have bones or teeth that can be preserved as fossils.”
Fortunately, during the lush Lower Cretaceous era, freshwater lakes covered Inner Mongolia. These waters were chock-full with the ancestors of today’s lampreys, and many fossils became beautifully preserved in a layer of late-Cretaceous shale, including larvae.
“This type of rock preserves very fine details of fossils,” Miao said. “The same rock preserved evidence of dinosaur feathers from this era. The lamprey larvae were found by local people and some by our Chinese colleagues who specialize in early fishes.”
According to the KU researcher and fellow authors Meemann Chang, Feixiang Wu and Jiangyong Zhang of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing, the larval fossils show the life cycle of the lamprey “emerged essentially in its present mode no later than the Early Cretaceous.”
This cycle consists of a long-lasting larval stage, a metamorphosis and a comparatively brief adulthood with a markedly different anatomy, according to the PNAS paper. The larvae come from the fossil lamprey species Mesomyzon mangae.
“Our larvae look modern,” Miao said. “The developmental stage is almost identical to today’s lamprey. Before this, we didn’t know how long lampreys have developed via metamorphosis. Now, we know it goes back 125 million years at least. In other words, lampreys haven’t changed much — and that’s very interesting.”
Then, like today, lampreys lived in both freshwater and saltwater. At the larval stage, they’d have dwelled in the sand or mud and drawn nutrients from micro-organisms in the water. Then, as mature lampreys, some of them would have subsisted by fastening themselves to host organisms and swigging their blood — often killing their host in the end.
“They attach to larger fish or whales,” Miao said. “They hold on forever.”
The National Basic Research Program of China, the Asian-Swedish Research Partnership Program of the Swedish Research Council and KU Endowment supported this research.
Note : The above story is based on materials provided by University of Kansas.
