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Water-rich gem points to vast ‘oceans’ beneath the Earth

The first terrestrial discovery of ringwoodite by University of  Alberta scientist Graham Pearson confirms the presence  of massive amounts of water 400 to 700 km beneath the Earth’s surface. Credit: University of Alberta

A University of Alberta diamond scientist has found the first terrestrial sample of a water-rich gem that yields new evidence about the existence of large volumes of water deep beneath the Earth.
An international team of scientists led by Graham Pearson, Canada Excellence Research Chair in Arctic Resources at the U of A, has discovered the first-ever sample of a mineral called ringwoodite. Analysis of the mineral shows it contains a significant amount of water—1.5 per cent of its weight—a finding that confirms scientific theories about vast volumes of water trapped 410 to 660 kilometres beneath the Earth, between the upper and lower mantle.

/div> “This sample really provides extremely strong confirmation that there are local wet spots deep in the Earth in this area,” said Pearson, a professor in the Faculty of Science, whose findings were published March 13 in Nature. “That particular zone in the Earth, the transition zone, might have as much water as all the world’s oceans put together.”

Diamond sample JUc29, from Juina, Brazil, containing the hydrous ringwoodite inclusion reported by Pearson et al., Nature 2014. Credit: Richard Siemens, University of Alberta

Ringwoodite is a form of the mineral peridot, believed to exist in large quantities under high pressures in the transition zone. Ringwoodite has been found in meteorites but, until now, no terrestrial sample has ever been unearthed because scientists haven’t been able to conduct fieldwork at extreme depths.

Pearson’s sample was found in 2008 in the Juina area of Mato Grosso, Brazil, where artisan miners unearthed the host diamond from shallow river gravels. The diamond had been brought to the Earth’s surface by a volcanic rock known as kimberlite—the most deeply derived of all volcanic rocks.

The discovery that almost wasn’t

Pearson said the discovery was almost accidental in that his team had been looking for another mineral when they purchased a three-millimetre-wide, dirty-looking, commercially worthless brown diamond. The ringwoodite itself is invisible to the naked eye, buried beneath the surface, so it was fortunate that it was found by Pearson’s graduate student, John McNeill, in 2009.

“It’s so small, this inclusion, it’s extremely difficult to find, never mind work on,” Pearson said, “so it was a bit of a piece of luck, this discovery, as are many scientific discoveries.”

The sample underwent years of analysis using Raman and infrared spectroscopy and X-ray diffraction before it was officially confirmed as ringwoodite. The critical water measurements were performed at Pearson’s Arctic Resources Geochemistry Laboratory at the U of A. The laboratory forms part of the world-renowned Canadian Centre for Isotopic Microanalysis, also home to the world’s largest academic diamond research group.

The study is a great example of a modern international collaboration with some of the top leaders from various fields, including the Geoscience Institute at Goethe University, University of Padova, Durham University, University of Vienna, Trigon GeoServices and Ghent University.

For Pearson, one of the world’s leading authorities in the study of deep Earth diamond host rocks, the discovery ranks among the most significant of his career, confirming about 50 years of theoretical and experimental work by geophysicists, seismologists and other scientists trying to understand the makeup of the Earth’s interior.

Scientists have been deeply divided about the composition of the transition zone and whether it is full of water or desert-dry. Knowing water exists beneath the crust has implications for the study of volcanism and plate tectonics, affecting how rock melts, cools and shifts below the crust.

“One of the reasons the Earth is such a dynamic planet is the presence of some water in its interior,” Pearson said. “Water changes everything about the way a planet works.”

The above story is based on materials provided by University of Alberta.

Ferberite

Chemical Formula: FeWO4
Locality: Aquiles, Sierra Almagrera, Spain.
Name Origin: Named after Moritz Rudolph Ferber (1805-1875) of Gera, Germany.Ferberite is the iron endmember of the manganese – iron wolframite solid solution series. The manganese endmember is hübnerite. Ferberite is a black monoclinic mineral composed of iron(II) tungstate, FeWO4.Ferberite and hübnerite often contain both divalent cations of iron and manganese, with wolframite as the intermediate species for which the solid solution series is named.

Ferberite occurs as granular masses and as slender prismatic crystals. It has a Mohs hardness of 4.5 and a specific gravity of 7.4 to 7.5. Ferberite typically occurs in pegmatites, granitic greisens, and high temperature hydrothermal deposits. It is a minor ore of tungsten.

Ferberite was discovered in 1863 in Sierra Almagrera, Spain, and named after the German mineralogist Moritz Rudolph Ferber (1805–1875).

Physical Properties

Cleavage: {010} Perfect, {100} Parting, {102} Parting
Color:  Black.
Density: 7.5 – 7.4, Average = 7.45
Diaphaneity: Nearly opaque
Fracture: Brittle – Uneven – Very brittle fracture producing uneven fragments.
Hardness: 4.5 – Between Fluorite and Apatite
Luster: Sub Metallic
Streak: brownish black

Photos :

Ferberite (twins) on matrix Locality: Tasna Mine, Rosario section of Cerro Tasna, Atocha-Quechisla District, Nor Chichas Province, Potosi Department, Bolivia Specimen Size: 11.2 x 8.4 x 8.2 cm Largest Crystal: 4.6 cm © minclassics
Ferberite (multi-twinned specimen!) Locality: Tasna Mine, Rosario section of Cerro Tasna, Atocha-Quechisla District, Nor Chichas Province, Potosi Department, Bolivia Specimen Size: 8.2 x 3.6 x 3.6 cm © minclassics
Yaogangxian Mine, Yaogangxian W-Sn ore field, Yizhang Co ., Chenzhou Prefecture, Hunan Province, China © Dan & Diana Weinrich

Solving the Midwest’s biggest geologic mystery

Kayakers on Lake Superior in the Apostle Islands National  Lakeshore, paddling along rocks deposited late in the evolution of the Midcontinent Rift. Credit: Seth Stein

Geologists from Northwestern University, the University of Illinois at Chicago, the University of Oklahoma and Purdue University have a new explanation for the Midwest’s biggest geologic mystery: What caused the giant 2,000-mile-long rift that starts in Lake Superior and runs south to Oklahoma and Alabama?

Using new data from the North American Midcontinent Rift and observations of rifting occurring today between Africa and Arabia, the scientists propose that the Midcontinent Rift formed when rocks now in South America rifted away from North America, forming a new ocean. As a result, rocks from the two sides match like pieces of a jigsaw puzzle.

The study was published March 5 in the journal Geophysical Research Letters.

A little more than a billion years ago, North America started to split, and 350,000 cubic miles of volcanic rock poured out. These rocks formed the valley that Lake Superior filled, and thick rock layers are exposed in the rift’s northern reaches but are underground elsewhere. The rocks of the Midcontinent Rift can be traced for thousands of miles underground because they are dense and highly magnetized.

“Although the rift made the Midwest’s best geology and scenery, we’ve never had a good explanation for what caused it,” said the study’s lead author, Carol A. Stein, professor of Earth and Environmental Sciences at the University of Illinois at Chicago. “The best we could do was to say that a plume of hot stuff came up under North America, for some unknown reason, and then stopped. That was never a satisfying explanation.”

To solve the puzzle, the geologists looked at a similar geologic feature forming today, the East African Rift that is splitting up Africa, causing the huge rift valley and volcanoes like Mount Kilimanjaro.

“The rift system is splitting Africa and rifting Arabia away from it, forming new ocean basins in the Red Sea and Gulf of Aden,” explained Seth Stein, the William Deering Professor of Geological Sciences at Northwestern’s Weinberg College of Arts and Sciences. “We see the same thing at other times in the past—rifts form and break continents apart. Once rifting succeeds in forming a new ocean, the leftover piece of rift shuts down. This seems to be how the Midcontinent Rift formed.”

Detailed mapping of the underground Midcontinent Rift using gravity data from G. Randy Keller, professor of geophysics at the University of Oklahoma in Norman and director of the Oklahoma Geological Survey, shows that the rift extends much farther than had been previously thought.

“It’s not just in the middle of the continent—it goes all the way to what was then the edge of the continent,” Keller said.

After putting the lines of evidence together, Carol Stein said, “The whole story now makes sense. We used to think of the Midcontinent Rift as this weird feature that started and died in the middle of a continent. Now we realize it formed as part of the rifting that split rocks now in South America off from North America. So instead of being a mysterious special case, we realize it formed in a way that’s familiar to geologists and what we see today and in the past. That’s gratifying because scientists hate to invoke special cases.”

The study is part of the National Science Foundation’s EarthScope program, in which geologists from across the U.S. are studying how North America formed.

Seth Stein, one of EarthScope’s organizers, said, “This is the kind of big advance we were hoping for. You can never predict breakthroughs, but when good people work together they often happen. It’s great that we got one for the Midwest because sometimes people think that exciting geology only happens in places like California. We hope results like this will encourage young Midwesterners to study geology and make even further advances.”

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

Ocean food web is key in the global carbon cycle

This graphic shows the global carbon budget with black  arrows and values reflecting the natural carbon cycle and red the anthropogenic perturbation.  Credit: 2007 IPCC report

Nothing dies of old age in the ocean. Everything gets eaten and all that remains of anything is waste. But that waste is pure gold to oceanographer David Siegel, director of the Earth Research Institute at UC Santa Barbara.

In a study of the ocean’s role in the global carbon cycle, Siegel and his colleagues used those nuggets to their advantage. They incorporated the lifecycle of phytoplankton and zooplankton—small, often microscopic animals at the bottom of the food chain —into a novel mechanistic model for assessing the global ocean carbon export. Their findings appear online in the journal Global Biogeochemical Cycles.

The researchers used satellite observations including determinations of net primary production (NPP)—the net production of organic matter from aqueous carbon dioxide (CO2) by phytoplankton—to drive their food-web-based model. The scientists focused on the ocean’s biological pump, which exports organic carbon from the euphotic zone—the well-lit, upper ocean—through sinking particulate matter, largely from zooplankton feces and aggregates of algae. Once these leave the euphotic zone, sinking into the ocean depths, the carbon can be sequestered for a season or for centuries.

“What we’ve done here is create the first step toward monitoring the strength and efficiency of the biological pump using satellite observations,” said Siegel, who is also a professor of marine science in UCSB’s Department of Geography. “The approach is unique in that previous ways have been empirical without considering the dynamics of the ocean food web.” The space/time patterns created by those empirical approaches are inconsistent with how oceanographers think the oceans should work, he noted.

Carbon is present in the atmosphere and is stored in soils, oceans and the Earth’s crust. Any movement of carbon between—or in the case of the ocean, within—these reservoirs is called a flux. According to the researchers, oceans are a central component in the global carbon cycle through their storage, transport and transformations of carbon constituents.

Shown are the links among the ocean’s biological pump  and pelagic food web. Light blue waters are the euphotic zone, while the darker blue waters represent  the twilight zone. Credit: US Joint Global Ocean Flux Study

“Quantifying this carbon flux is critical for predicting the atmosphere’s response to changing climates,” Siegel said. “By analyzing the scattering signals that we got from satellite measurements of the ocean’s color, we were able to develop techniques to calculate how much of the biomass occurs in very large or very small particles.”

Their results predict a mean global carbon export flux of 6 petagrams (Pg) per year. Also known as a gigaton, a petagram is equal to one quadrillion (1015) grams. This is a huge amount, roughly equivalent to the annual global emissions of fossil fuel. At present, fossil fuel combustion represents a flux to the atmosphere of approximately 9 Pg per year.

Global mean determinations of the efficiency of the biological pump from (left) the present food-web model and (right) an empirical method that models export efficiency as a function  of the sea surface temperature (SST). Credit: UCSB

“It matters how big and small the plankton are, and it matters what the energy flows are in the food web,” Siegel said. “This is so simple. It’s really who eats whom but also having an idea of the biomasses and productivity of each. So we worked out these advanced ways of determining NPP, phytoplankton biomass and the size structure to formulate mass budgets, all derived from satellite data.”

The researchers are taking their model one step further by planning a major field program designed to better understand the states in which the biological pump operates. “Understanding the biological pump is critical,” Siegel concluded. “We need to understand where carbon goes, how much of it goes into the organic matter, how that affects the air-sea exchanges of CO2 and what happens to fossil fuel we have emitted from our tailpipes.”

Note : The above story is based on materials provided by University of California – Santa Barbara

New method gives way to non-invasive subsurface data

This method could be used in place of having to drill a  ‘monitoring well’ as done in conventional cross-well surveys. Credit: Eric Hodel

A hydro-geologist has found an inexpensive, high-quality three-dimensional imaging method for aquifers and other below-ground features.

Conventional cross-well surveys require a monitoring bore containing sensors, and another source well in which a seismic shock is produced.

Now, PhD student Majed Al Malki has eliminated the need for a dedicated monitoring well, if two bores are already available.He developed a method whereby he placed sensors in two existing vertical wells and created a shock wave at a fixed point on the surface.

He then measured and interpreted the differences between signals received at varying depths in the two wells to produce an image of the geology in between.

“When compared to conventional walkaway vertical seismic profiling, the only additional effort required to complete dual-well walkaway vertical seismic profiling is the deployment of seismic sensors in the second well,” Dr Al Malki says.

He conducted the experiments at the Water Corporation’s Mirrabooka aquifer storage and recovery site during his PhD studies, under the supervision of Curtin University Associate Professor Brett Harris.

“[This project] was looking at banking excess water in the shallow aquifers into deeper aquifers that are slightly depleted,” Prof Harris says.

“The main thing was to look for ways of characterising the rock around those formations.”
He says they used a 1000kg piece of concrete, dropped from a Bobcat, as a weight-drop source of seismic energy.

“[The] surface source bangs the ground on, in our case, about 150 locations and then we use the energy as it propagates through the earth between the two wells.

“The path of the seismic energy goes from one well to the other well but all at different angles from the different source positions on the surface.”

He says this allows them to reconstruct sub-surface source positions in the well nearest to the seismic energy source.

“It looks like there was a source there without you actually having to put one there,” he says.
“That information can be used to actually reconstruct what a source would look like if it were located underground.”

He says the beauty of this method is that there is no need to place a seismic shock source inside a purpose-drilled hole.

“It’s really a non-invasive method of understanding what the distribution of the key interfaces are,” Prof Harris says.

He says the technique could be applied to assess underground environments for petroleum, geothermal and groundwater reserves and carbon storage sites.

Note : The above story is based on materials provided by Science Network WA

Fairfieldite

Fairfieldite Locality: Ryerson Hill Quarries, Paris, Oxford Co., Maine, USA Field of View: 1.25 mm Copyright © Dick Dionne

Chemical Formula: Ca2(Mn,Fe2+)(PO4)2·2(H2O)
Locality: Branchville, Redding, Fairfield County, Connecticut, USA.
Name Origin: Named for the locality.

Physical Properties

Color: Greenish white, White, Light yellow.
Density: 3.1
Diaphaneity: Transparent
Fracture: Brittle – Uneven – Very brittle fracture producing uneven fragments.
Hardness: 3.5 – Copper Penny
Luminescence: Non-fluorescent.
Luster: Vitreous – Pearly
Streak: white

Photo :

Fairfieldite Cigana claim , Conselheiro Pena, Doce valley, Minas Gerais, Brazil Specimen weight:66 gr. Crystal size:up to 1 mm Overall size: 62mm x 42 mm x 40 mm © minservice
Foote Lithium Co. Mine (Foote Mine), Kings Mountain District, Cleveland Co., North Carolina, USA © 2005 JBS

Dinosaur-killing impact acidified oceans: study

A file picture taken on March 13, 2009 shows the skeleton of a Cryolophosaurus Ellioti, diplayed at the exhibition “Dinosaurs of Gondwana” at the National Science Museum in Tokyo

The space rock that smashed into Earth 65 million years ago, famously wiping out the dinosaurs, unleashed acid rain that turned the ocean surface into a witches’ brew, researchers said Sunday.

Delving into the riddle of Earth’s last mass extinction, Japanese scientists said the impact instantly vaporised sulphur-rich rock, creating a vast cloud of sulphur trioxide (SO3) gas.

This mixed with water vapour to create sulphuric acid rain, which would have fallen to the planet’s surface within days, acidifying the surface levels of the ocean and killing life therein.

Those species that were able to survive beneath this lethal layer eventually inherited the seas, according to the study which did not delve into the effects on land animals.

“Concentrated sulphuric acid rains and intense ocean acidification by SO3-rich impact vapours resulted in severe damage to the global ecosystem and were probably responsible for the extinction of many species,” the study said.

The great smashup is known as the Cretaceous-Tertiary extinction.

It occurred when an object, believed to be an asteroid some 10 kilometres (six miles) wide, whacked into the Yucatan peninsula in modern-day Mexico.

It left a crater 180 kilometres (110 miles) wide, ignited a firestorm and kicked up a storm of dust that was driven around the world on high winds, according to the mainstream scenario.

Between 60 and 80 percent of species on Earth were wiped out, according to fossil surveys.

Large species suffered especially: dinosaurs which had roamed the land for some 165 million years, were replaced as the terrestrial kings by mammals.

Extinction riddle

Much speculation has been devoted to precisely how the mass die-out happened.

A common theory is that a “nuclear winter” occurred—the dust pall prevented sunlight reaching the surface, causing vegetation to shrivel and die, and dooming the species that depended on them.

Another, fiercely debated, idea adds acid rain to the mix.

Critics say the collision was far likelier to have released sulphur dioxide (SO2) than SO3, the culprit chemical in acid rain. And, they argue, it would have lingered in the stratosphere rather than fallen back to Earth.

Seeking answers, a team led by Sohsuke Ohno of the Planetary Exploration Research Centre in Chiba set up a special lab rig to replicate—on a tiny scale—what happened that fateful day.

They used a laser beam to vaporise a strand of plastic, which released a high-speed blast of plasma and caused a tiny piece of foil, made of the heavy metal tantalum, to smash into a sample of rock.

The heavy foil fragment replicated on a miniscule scale the mass of the asteroid, while the rock was of a similar makeup as the surface where the asteroid struck.

The team caused collisions ranging from 13 to 25 km per second (47,000-90,000 km or 29,000-55,000 miles per hour), and analysed the gas that was released.

The research, reported in the journal Nature Geoscience, showed that SO3 was by far the dominant molecule, not SO2.

The team also carried out a computer simulation of larger silicate particles that would have been ejected by the impact, and found they too played a part.

The articles rapidly bound with the poisonous vapour to become sulphur acid “aerosols” that fell to the surface.

Heavily acidic waters would explain the overwhelming extinction among surface species of plankton called foraminifera.

Foraminifera are single-celled creatures protected by a calcium carbonate shell, which dissolves in acidic water.

The “acid rain” scenario also helps explain other extinction riddles, including why there was a surge in the number of ferns species after the impact. Ferns love acidic, water-logged conditions such as those described in the study.

Note : The above story is based on materials provided by © 2014 AFP

Volcanoes helped species survive ice ages, research says

This image shows a man standing in volanic steam in Antartica. Credit: Peter Convey, British Antartic Survey
An international team of researchers has found evidence that the steam and heat from volcanoes and heated rocks allowed many species of plants and animals to survive past ice ages, helping scientists understand how species respond to climate change.

The research could solve a long-running mystery about how some species survived and continued to evolve through past ice ages in parts of the planet covered by glaciers.

The team, led by Dr Ceridwen Fraser from the Australian National University and Dr Aleks Terauds from the Australian Antarctic Division, studied tens of thousands of records of Antarctic species, collected over decades by hundreds of researchers, and found there are more species close to volcanoes, and fewer further away.

“Volcanic steam can melt large ice caves under the glaciers, and it can be tens of degrees warmer in there than outside. Caves and warm steam fields would have been great places for species to hang out during ice ages,” Dr Fraser said.

“We can learn a lot from looking at the impacts of past climate change as we try to deal with the accelerated change that humans are now causing.”

While the study was based on Antarctica, the findings help scientists understand how species survived past ice ages in other icy regions, including in periods when it is thought there was little or no ice-free land on the planet.

Antarctica has at least 16 volcanoes which have been active since the last ice age 20,000 years ago.
The study examined diversity patterns of mosses, lichens and bugs which are still common in Antarctica today.

Professor Peter Convey from the British Antarctic Survey said around 60 per cent of Antarctic invertebrate species are found nowhere else in the world.

“They have clearly not arrived on the continent recently, but must have been there for millions of years. How they survived past ice ages – the most recent of which ended less than 20,000 years ago – has long puzzled scientists,” Professor Convey said.

Dr Terauds of the Australian Antarctic Division ran the analyses, and says the patterns are striking.
“The closer you get to volcanoes, the more species you find. This pattern supports our hypothesis that species have been expanding their ranges and gradually moving out from volcanic areas since the last ice age,” Dr Terauds said.

Professor Steven Chown, from Monash University, says the research findings could help guide conservation efforts in Antarctica.

“Knowing where the ‘hotspots’ of diversity are will help us to protect them as human-induced environmental changes continue to affect Antarctica,” Professor Chown said.

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

Euxenite-(Y)

Euxenite-(Y) Locality: Beryl Pit (Quadeville East mine), Lyndoch Township, Renfrew Co., Ontario, Canada FOV: 14mm Copyright © David K. Joyc

Chemical Formula: (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Locality: Jolster, Sondfjord, Norway.
Name Origin: From the Greek for “friendly to strangers, hospitable,” in allusion to the rare elements that it contains.

Euxenite, which is sometimes named euxenite-(Y) (the Y is for the yttrium), is a mineral that is sometimes called a “trash can mineral”. Because it will accommodate a wide variety of elements in its crystal structure, generally the elements that other minerals do not seem to want, ie the “trash”. For euxenite, these elements are in a group called the rare earths and are sometimes quite valuable, making euxenite a potentially profitable ore. Euxenite’s name is from a Greek phrase meaning “hospitable”, another reference to its . . . accommodating nature.

Euxenite is in a series with the mineral polycrase, another “trash can mineral”. Polycrase is simply richer in titanium as opposed to the niobium rich euxenite. The other elements can be found in both minerals and the structure is basically the same.

Physical Properties

Cleavage: None
Color:  Brownish black, Brown, Yellow, Olive green.
Density: 4.7 – 5, Average = 4.84
Diaphaneity: Translucent to opaque
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 6.5 – Pyrite
Luminescence: Non-fluorescent.
Luster: Greasy (Oily)
Streak: reddish brown

Photos :

Euxenite 5.3×3.8×5.2 cm Beryl Pit Quadeville, Renfrew County Ontario, Canada Copyright © David K. Joyce Minerals
Euxenite 2.2×1.5×0.8 cm Beryl Pit Quadeville, Renfrew County Ontario, Canada Copyright © David K. Joyce Minerals
Hilltveit (Hiltveit), Iveland, Aust-Agder, Norway © B. Otter

Eudialyte

Eudialyte Locality: Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire), Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada Picture width 4 mm. © Stephan Wolfsried

Chemical Formula: Na15Ca6(Fe2+,Mn2+)3Zr3[Si25O73](O,OH,H2O)3(OH,Cl)2
Locality: Julianehaab district of Greenland.
Name Origin: From the Greek eu – “well” and dialytos – “decomposable.”

Eudialyte, whose name derives from the Greek phrase Εὖ διάλυτος eu dialytos, meaning “well decomposable”, is a somewhat rare, nine member ring cyclosilicate mineral, which forms in alkaline igneous rocks, such as nepheline syenites. Its name alludes to its ready solubility in acid.

Eudialyte was first described in 1819 for an occurrence in nepheline syenite of the Ilimaussaq intrusive complex of southwest Greenland.

Alternative names

Alternative names of eudialyte include: almandine spar, eudalite, Saami blood. Eucolite is the name of an optically negative variety, more accurately the group member: ferrokentbrooksite.

Physical Properties

Cleavage: {0001} Imperfect
Color: Pinkish red, Red, Yellow, Yellowish brown, Violet.
Density: 2.8 – 3, Average = 2.9
Diaphaneity: Transparent to Translucent
Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern.
Hardness: 5-5.5 – Apatite-Knife Blade
Luminescence: Non-fluorescent.
Luster: Vitreous (Glassy)
Streak: white

Photos :

Aegirine and eudialyte, Kedykwerpakh Mt., Lovozero Massif, Kola Peninsula, Russia Size: 6 x 5.5 x 4 cm © SpiriferMinerals
Aegirine and eudialyte, Kedykwerpakh Mt., Lovozero Massif, Kola Peninsula, Russia Size: 7 x 4.5 x 3.2 cm © SpiriferMinerals
Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire), Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada © Stephan Wolfsried

Pridoli Epoch

Pridoli Series, uppermost of four main divisions of the Silurian System, representing those rocks deposited worldwide during the Pridoli Epoch (423 million to 419.2 million years ago). The series name is derived from the Pridoli area of the Daleje Valley on the outskirts of Prague in the Czech Republic, where about 20 to 50 metres (about 65 to 165 feet) of platy limestone strata rich in cephalopods and bivalves are well-developed.

By international agreement, the base of the Pridoli Series is defined by the first occurrence of the graptolite species Monograptus parultimus in rock exposures at the entrance to the Pozary Quarries, which lie about 1.5 km (about 1 mile) east of Reporyje, outside of southwestern Prague. The M. parultimus biozone, in short, constitutes the global stratotype section and point (GSSP) for the base of the series. In addition, two species of chitinozoans (a type of marine plankton), Urnochitina urna and Fungochitina kosovensis, first occur at or just above the base of the series. The earliest known simple vascular land plants, of the genus Cooksonia, typically occur in the lower portions of the Pridoli Series in many parts of the world. The Pridoli Series is overlain by the Lochkovian Stage, the first stage of the Devonian System. The base of the Lochkovian and the base of the Devonian System automatically define the top of the Pridoli and thus the top of the Silurian System. The Pridoli Series has not been divided into stages and is underlain by the Ludlow Series.

Note : The above story is based on materials provided by Encyclopædia Britannica, Inc.

Ludlow Epoch

The Ludlow Group are rocks deposited during the Ludlow period of the Silurian in Great Britain. This group contains the following formations in descending order:

  1. Cilestones, Downton Castle sandstones (90 ft./27.7 m),
  2. Ledbury shales 270 ft./83 m),
  3. Upper Ludlow rocks (140 ft./43 m),
  4. Aymestry limestone (up to 40 ft./12.3 m),
  5. Lower Ludlow rocks (350 to 780 ft./108 m-240 m).

The Ludlow group is essentially shaly in character, except towards the top, where the beds become more sandy and pass gradually into the Old Red Sandstone. The Aymestry limestone, which is irregular in thickness, is sometimes absent, and where the underlying Wenlock limestones are absent the shales of the Ludlow group graduate, downwards into the Wenlock shales. The group is typically developed between Ludlow and Aymestrey, and it occurs also in the detached Silurian areas between Dudley and the mouth of the Severn.

The Lower Ludlow rocks are mainly grey, greenish and brown mudstones and sandy and calcareous shales. They contain an abundance of fossils. The series has been zoned by means of the Graptolites by E. M. R. Wood; the following in ascending order, are the zonal forms:

  1. Monograptus vulgaris,
  2. M. Nilssoni,
  3. M. scanicus,
  4. M. tumescens and
  5. M. leintwardinensis.

Cyathaspis ludensis, the earliest British vertebrate fossil, was found in these rocks at Leintwardine in Herefordshire, a noted fossil locality. Trilobites are numerous (Phacops caudatus, Lichas anglicus, Homolonotus delphinocephalus, Calymene Blumenbachii); brachiopods (Leptaena rhomboidalis, Rhynchonella Wilsoni, Atrypa reticularis}, pelecypods (Cardiola interrupts, Ctenodonta sulcata) and gasteropods and cephalopods (many species of Orthoceras and also Gomphoceras, Trochoceras) are well represented. Other fossils are Ceratiocaris , Pterygotus, Protaster, Palaeocoma and Palaeodiscus.

The Upper Ludlow rocks are mainly soft mudstones and shales with some harder sandy beds capable of being worked as building-stones. These sandy beds are often found covered with ripple-marks and annelid tracks; one of the uppermost sandy layers is known as the ” Fucoid bed ” from the abundance of the seaweed-like impressions it bears. At the top of this sub-group, near Ludlow, a brown layer occurs, from a quarter of an inch to 4 in. (63 mm to 100 mm) in thickness, full of the fragmentary remains of fish associated with those of Pterygotus and mollusca. This layer, known as the ” Ludlow Bone bed,” has been traced over a very large area (see Bone Bed). The common fossils include plants (Actinophyllum, Chondrites), ostracods, phyllocarids, eurypterids, trilobites (less common than in the older groups), numerous brachiopods (Lingula minima, Chonetes striatella), gasteropods, pelecypods and cephalopods (Orthoceras bullatum). Fish include Cephalaspis, Cyathaspis, Auchenaspis. The Tilestones, Downton Castle Sandstone and Ledbury shales are occasionally grouped together under the term Downtonian. They are in reality passage beds between the Silurian and Old Red Sandstone, and were originally placed in the latter system by Sir R. I. Murchison. They are mostly grey, yellow or red micaceous, shaly sandstones. Lingula cornea, Platyschisma helicites and numerous phyllocarids and ostracods occur among the fossils.

In Denbighshire and Merionethshire the upper portion of the Denbighshire Grits belongs to this horizon: viz. those from below upwards, the Nantglyn Flags, the Upper Grit beds, the Monograptus leintwardinensis beds and the Dinas Bran beds. In the Silurian area of the Lake district the Coldwell beds, forming the upper part of the Coniston Flags, are the equivalents of the Lower Ludlow; they are succeeded by the Coniston Grits (4,000 ft./1,230 m), the Bannisdale Slates (5200 ft./1,600 m) and the Kirkby Moor Flags (2,000 ft./615 m).

In the Silurian areas of southern Scotland, the Ludlow rocks are represented in the Kirkcudbright Shore and Riccarton district by the Raeberry Castle beds and Balmae Grits (500-750 ft.). In the northern belt Lanarkshire and the Pentland Hillsthe lower portion (or Ludlovian) consists of mudstones, flaggy shales and greywackes; but the upper (or Downtonian) part is made up principally of thick red and yellow sandstones and conglomerates with green mudstones. The Ludlow rocks of Ireland include the ” Salrock beds ” of County Galway and the “Croagmarhin beds” of Dingle promontory.

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

Wenlock Epoch

The Wenlock (seldomly also referred to as Wenlockian) is the second series of the Silurian. It is preceded by the Llandovery series and followed by the Ludlow. Radiometric dates constrain the Wenlockian between 433.4 ± 0.8 and 427.4 ± 0.5 million years ago.

Naming and history

The Wenlock is named after Wenlock Edge, an outcrop of rocks near the town of Much Wenlock in Shropshire (West Midlands, United Kingdom). The name was first used in the term “Wenlock and Dudley rocks” by Roderick Murchison in 1834 to refer to the limestones and underlying shales that underlay what he termed the “Ludlow rocks”. He later modified this term to simply the “Wenlock rocks” in his the Silurian System in 1839.

Definition and subdivision

The Wenlock’s beginning is defined by the lower boundary (or GSSP) of the Sheinwoodian. The end is defined as the base (or GSSP) of the Gorstian.

The Wenlock is divided into the older Sheinwoodian and the younger Homerian stage. The Sheinwoodian lasted from 433.4 ± 0.8 to 430.5 ± 0.7 million years ago. The Homerian lasted from 430.5 ± 0.7 to 427.4 ± 0.5 million years ago.

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

Llandovery Epoch

In geology, the Llandovery Group refers to the lowest division of the Silurian period (Upper Silurian) in Britain. It is named after the town of Llandovery in Wales, although Charles Lapworth had proposed the name Valentian (from the Roman British province of Valentia) for this group in 1879. It includes the Tarannon Shales (1000-1500 ft.), Upper Llandovery and May Hill Sandstone (800 ft.), Lower Llandovery, (600-1500 ft.)

The Lower Llandovery rocks consist of conglomerates, sandstones and slaty beds. At Llandovery they rest upon Ordovician rocks. These rocks occur with a narrow crop in Pembrokeshire, which curves round through Llandovery, and in the Rhayader district they reach a considerable thickness. They also occur in Ceredigion and Carmarthenshire.

The Upper Llandovery has local lenticular developments of shelly limestone (Norbury, Hollies and Pentamerus limestones). It occurs with a narrow outcrop in Carmarthenshire at the base of the Silurian, disappearing beneath the Old Red Sandstone westward to reappear in Pembrokeshire; north-eastward the outcrop extends to the Long Mynd, which the conglomerate wraps round. As it is followed along the crop it rests upon the Lower Llandovery, Caradog, Llandeilo, Cambrian and pre-Cambrian rocks. The fossils include the trilobites Phacops caudata, Encrinurus punctatus and Calymene blumenbachis; the brachiopods Pentamerus oblongus, Orthis calligramma and Atrypa reticularis; the corals Favosites and Lindostroemia; and the zonal graptolites Rastriles maximus and Monograptus spinigerus.

The Tarannon shales, grey and blue slates, designated by Adam Sedgwick the Paste Rock, is traceable from Conwy into Carmarthenshire; in Ceredigion, there are gritty beds; and in the neighbourhood of Builth, soft dark shales. The group is poor in fossils, with the exception of graptolites; of these Cyrtograptus grayae and Monograptus exiguus are zonal forms. The Tarannon group is represented by the Rhayader Pale Shales in Powys; in the Moffat Silurian belt in south Scotland by a thick development, including the Hawick rocks and Ardwell Beds, and the Queensberry Group or Gala; in the Girvan area, by the Drumyork Flags, Bargany Group and Penkill Group; and in Ireland by the Treveshilly Shales of Strangford Lough, and the shales of Salterstown, Co. Louth.

The Upper and Lower Llandovery rocks are represented in descending order by the Pale Shales, Graptolite Shales, Grey Slates and Corwen Grit of Meirionnydd and Denbighshire. In the Lake district the lower part of the Stockdale shales (Skelgill beds) is of Llandovery age. In the Girvan area to the north their place is taken by the Camregan, Shaugh Hill and Mullock Hill groups. In Ireland the Llandovery rocks are represented by the Anascaul Slates of the Dingle promontory, by the Owenduff and Gowlaun Grits, Co. Galway, by the Upper Pomeroy Beds, by the Uggool and Ballaghaderin Beds, Co. Mayo, and by rocks of this age in Coalpit Bay and Slieve Felim Mountains.

Economic deposits in Llandovery rocks include slate pencils (Teesdale), building stone, flag-stone, road metal and lime.

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

New dinosaur found in Portugal, largest terrestrial predator from Europe

The new dinosaur species is estimated up to 10 meters long and 4-5 tons. Credit: Christophe Hendrickx; CC-BY

A new dinosaur species found in Portugal may be the largest land predator discovered in Europe, as well as one of the largest carnivorous dinosaurs from the Jurassic, according to a paper published in PLOS ONE on March 5, 2014 by co-authors Christophe Hendrickx and Octavio Mateus from Universidade Nova de Lisboa and Museu da Lourinhã.

Scientists discovered bones belonging to this dinosaur north of Lisbon. They were originally believed to be Torvosaurus tanneri, a dinosaur species from North America. Closer comparison of the shin bone, upper jawbone, teeth, and partial tail vertebrae suggest to the authors that it may warrant a new species name, Torvosaurus gurneyi.

T. gurneyi had blade-shaped teeth up to 10 cm long, which indicates it may have been at the top of the food chain in the Iberian Peninsula roughly 150 million years ago. The scientists estimate that the dinosaur could reach 10 meters long and weigh around 4 to 5 tons. The number of teeth, as well as size and shape of the mouth, may differentiate the European and the American Torvosaurus. The fossil of the upper jaw of T. tanneri has 11 or more teeth, while T. gurneyi has fewer than 11. Additionally, the mouth bones have a different shape and structure. The new dinosaur is the second species of Torvosaurus to be named.

“This is not the largest predatory dinosaur we know. Tyrannosaurus, Carcharodontosaurus, and Giganotosaurus from the Cretaceous were bigger animals,” said Christophe Hendrickx. “With a skull of 115 cm, Torvosaurus gurneyi was however one of the largest terrestrial carnivores at this epoch, and an active predator that hunted other large dinosaurs, as evidenced by blade shape teeth up to 10 cm.” Fossil evidences of closely related dinosaurs suggest that this large predator may have already been covered with proto-feathers. Recently described dinosaur embryos from Portugal are also ascribed to the new species of Torvosaurus.

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

Earth’s mantle plasticity explained

Optical microscopy image in cross polarized light of a natural olivine polycrystal (Oman mylonite). Credit: S. Demouchy, Montpellier

Earth’s mantle is a solid layer that undergoes slow, continuous convective motion. But how do these rocks deform, thus making such motion possible, given that minerals such as olivine (the main constituent of the upper mantle) do not exhibit enough defects in their crystal lattice to explain the deformations observed in nature? A team led by the Unité Matériaux et Transformations (CNRS/Université Lille 1/Ecole Nationale Supérieure de Chimie de Lille) has provided an unexpected answer to this question.

It involves little known and hitherto neglected crystal defects, known as ‘disclinations’, which are located at the boundaries between the mineral grains that make up rocks. Focusing on olivine, the researchers have for the first time managed to observe such defects and model the behavior of grain boundaries when subjected to a mechanical stress.

The findings, which have just been published in Nature, go well beyond the scope of the geosciences: they provide a new, extremely powerful tool for the study of the dynamics of solids and for the materials sciences in general.

Earth continuously releases its heat via convective motion in Earth’s mantle, which underlies the crust. Understanding this convection is therefore fundamental to the study of plate tectonics. The mantle is made up of solid rocks. In order for convective motion to occur, it must be possible for the crystal lattice of these rocks to deform. Until now, this was a paradox that science was unable to fully resolve. While defects in the crystal lattice, called dislocations, provide a very good explanation of the plasticity of metals, they are insufficient to explain the deformations undergone by certain mantle rocks.

The researchers suspected that the solution was to be found at the boundaries between the mineral grains that make up rocks. However, they lacked the conceptual tools needed to describe and model the role played by these boundaries in the plasticity of rocks.

Researchers at the Unité Matériaux et Transformations (CNRS/Université Lille 1/Ecole Nationale Supérieure de Chimie de Lille) in collaboration with researchers at the Laboratoire Géosciences Montpellier (CNRS/Université Montpellier 2) and the Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux (CNRS/Université de Lorraine/Arts et Métiers ParisTech/Ecole Nationale d’Ingénieurs de Metz) have now explained this role. They have shown that the crystal lattice of the grain boundaries exhibits highly specific defects known as ‘disclinations’, which had hitherto been neglected. The researchers succeeded in observing them for the first time in samples of olivine (which makes up as much as 60% of the upper mantle) by using an electron microscope and specific image processing. They even went further: based on a mathematical model, they showed that these disclinations provided an explanation for the plasticity of olivine. When mechanical stress is applied, the disclinations enable the grain boundaries to move, thus allowing olivine to deform in any direction. Flow in the mantle is thus no longer incompatible with its rigidity.

This research goes beyond explaining the plasticity of rocks in Earth’s mantle: it is a major step forward in materials science. Consideration of disclinations should provide scientists with a new tool to explain many phenomena related to the mechanics of solids. The scientists intend to continue their research into the structure of grain boundaries, not only in other minerals but also in other solids such as metals.

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

Plasma plumes help shield Earth from damaging solar storms

NASA images used in a photo composite. Credit: Christine Daniloff/MIT

Earth’s magnetic field, or magnetosphere, stretches from the planet’s core out into space, where it meets the solar wind, a stream of charged particles emitted by the sun. For the most part, the magnetosphere acts as a shield to protect Earth from this high-energy solar activity.

But when this field comes into contact with the sun’s magnetic field — a process called “magnetic reconnection” — powerful electrical currents from the sun can stream into Earth’s atmosphere, whipping up geomagnetic storms and space weather phenomena that can affect high-altitude aircraft, as well as astronauts on the International Space Station.

Now scientists at MIT and NASA have identified a process in Earth’s magnetosphere that reinforces its shielding effect, keeping incoming solar energy at bay.

By combining observations from the ground and in space, the team observed a plume of low-energy plasma particles that essentially hitches a ride along magnetic field lines — streaming from Earth’s lower atmosphere up to the point, tens of thousands of kilometers above the surface, where the planet’s magnetic field connects with that of the sun. In this region, which the scientists call the “merging point,” the presence of cold, dense plasma slows magnetic reconnection, blunting the sun’s effects on Earth.

“The Earth’s magnetic field protects life on the surface from the full impact of these solar outbursts,” says John Foster, associate director of MIT’s Haystack Observatory. “Reconnection strips away some of our magnetic shield and lets energy leak in, giving us large, violent storms. These plasmas get pulled into space and slow down the reconnection process, so the impact of the sun on the Earth is less violent.”

Foster and his colleagues publish their results in this week’s issue of Science. The team includes Philip Erickson, principal research scientist at Haystack Observatory, as well as Brian Walsh and David Sibeck at NASA’s Goddard Space Flight Center.

Mapping Earth’s magnetic shield

For more than a decade, scientists at Haystack Observatory have studied plasma plume phenomena using a ground-based technique called GPS-TEC, in which scientists analyze radio signals transmitted from GPS satellites to more than 1,000 receivers on the ground. Large space-weather events, such as geomagnetic storms, can alter the incoming radio waves — a distortion that scientists can use to determine the concentration of plasma particles in the upper atmosphere. Using this data, they can produce two-dimensional global maps of atmospheric phenomena, such as plasma plumes.

These ground-based observations have helped shed light on key characteristics of these plumes, such as how often they occur, and what makes some plumes stronger than others. But as Foster notes, this two-dimensional mapping technique gives an estimate only of what space weather might look like in the low-altitude regions of the magnetosphere. To get a more precise, three-dimensional picture of the entire magnetosphere would require observations directly from space.

Toward this end, Foster approached Walsh with data showing a plasma plume emanating from Earth’s surface, and extending up into the lower layers of the magnetosphere, during a moderate solar storm in January 2013. Walsh checked the date against the orbital trajectories of three spacecraft that have been circling the Earth to study auroras in the atmosphere.

As it turns out, all three spacecraft crossed the point in the magnetosphere at which Foster had detected a plasma plume from the ground. The team analyzed data from each spacecraft, and found that the same cold, dense plasma plume stretched all the way up to where the solar storm made contact with Earth’s magnetic field.

A river of plasma

Foster says the observations from space validate measurements from the ground. What’s more, the combination of space- and ground-based data give a highly detailed picture of a natural defensive mechanism in Earth’s magnetosphere.

“This higher-density, cold plasma changes about every plasma physics process it comes in contact with,” Foster says. “It slows down reconnection, and it can contribute to the generation of waves that, in turn, accelerate particles in other parts of the magnetosphere. So it’s a recirculation process, and really fascinating.”

Foster likens this plume phenomenon to a “river of particles,” and says it is not unlike the Gulf Stream, a powerful ocean current that influences the temperature and other properties of surrounding waters. On an atmospheric scale, he says, plasma particles can behave in a similar way, redistributing throughout the atmosphere to form plumes that “flow through a huge circulation system, with a lot of different consequences.”

“What these types of studies are showing is just how dynamic this entire system is,” Foster adds.

Note : The above story is based on materials provided by Massachusetts Institute of Technology.

Euclase

Euclase Alto do Giz pegmatite, Equador, Rio Grande do Norte, Brazil Miniature, 4.2 x 2.4 x 2.2 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Chemical Formula: BeAl(SiO4)(OH)
Locality: Orenburg district in the southern Urals, Russia.
Name Origin: From the Greek eu – “well” and klasis – “breaking.”Euclase is a beryllium aluminium hydroxide silicate mineral (BeAl(SiO4)(OH)). It crystallizes in the monoclinic crystal system and is typically massive to fibrous as well as in slender prismatic crystals. It is related to beryl (Be3Al2Si6O18) and other beryllium minerals. It is a product of the decomposition of beryl in pegmatites.Euclase crystals are noted for their blue color, ranging from very pale to dark blue. The mineral may also be colorless, white, or light green. Cleavage is perfect, parallel to the clinopinacoid, and this suggested to René Just Haüy the name euclase, from the Greek εὖ, easily, and κλάσις, fracture. The ready cleavage renders the crystals fragile with a tendency to chip, and thus detracts from its use for personal ornament. When cut it resembles certain kinds of beryl and topaz, from which it may be distinguished by its specific gravity (3.1). Its hardness (7.5) is similar to beryl (7.5 – 8), and a bit less than that of topaz (8).It was first reported in 1792 from the Orenburg district in the southern Urals, Russia, where it is found with topaz and chrysoberyl in the gold-bearing gravels of the Sanarka (nowadays probably, Sakmara River, Mednogorsk district, Orenburgskaya Oblast’). Its type locality is Ouro Prêto, Minas Gerais, Southeast Region, Brazil, where it occurs with topaz. It is found rarely in the mica-schist of the Rauris in the Austrian Alps.

Physical Properties

Cleavage: {010} Perfect
Color: Blue, Colorless, White, Light blue, Light green.
Density: 2.987 – 3.1, Average = 3.04
Diaphaneity: Transparent to translucent
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 7.5 – Garnet
Luminescence: Non-fluorescent.
Luster: Vitreous (Glassy)
Streak: white

Photos :

Euclase Ouro Preto, Minas Gerais, Brazil Size: 2.5 x 1.5 x 0.5 cm © danweinrich
EUCLASE Chivor Mine, Boyaca Depart, Colombia, South America Size: 2.4 x 1.5 x 0.8 cm (Miniature) Owner: Kristalle and Crystal Classics
Equador, Borborema mineral province, Rio Grande do Norte, Brazil © Joseph A. Freilich

Mineral targeting made easy with database

The magnetite database can help exploration geologists distinguish between barren and mineralised areas of land. Credit: David Clarke

Finding ways to target mineral deposits in remote and deeply covered areas, such as in WA’s often thick regolith cover, has been a major motivating factor in collaborative research between Australian and US scientists.

Exploring the use of magnetite as a pathfinder mineral, the study involved the CSIRO Minerals Down Under Flagship, University of WA’s Centre for Exploration Targeting and the US Geological Survey at Denver’s Central Mineral and Environmental Resources Science Centre.

Study co-author Patrick Nadoll, who is based at Kensington’s CSIRO Earth Science Resource Engineering, says a steadily growing magnetite chemistry database is showing distinctive compositional trends that can discriminate between hydrothermal (formed from water) and igneous (formed from lava or magma) magnetite.

“This helps exploration geologists find mineral deposits distal to the main mineralisation,” he says.

“The composition of igneous and hydrothermal magnetite is governed by several chemical and physical factors, such as temperature and fluid composition.

“Variations in the concentrations of key minor and trace elements represent a compositional signature that can fingerprint host rocks and mineral deposits.”

Main discriminator elements for magnetite are magnesium, aluminium, titanium, vanadium, chromium, manganese, cobalt, nickel, zinc, and gallium which are commonly present at detectable levels (10 to 1000 parts per million).

They display systematic variations across different types of mineral deposits and can also help to differentiate barren from mineralised areas.

“The use of statistical data exploration has been particularly helpful to find trends and patterns in large databases,” Dr Nadoll says.

“And the occurrence, abundance and composition of mineral inclusions in magnetite can also be a useful guide for exploration.

“For example, sulfide inclusions in magnetite are indicative for hydrothermal magnetite from sulfidic hydrothermal ore deposits such as skarn or porphyry deposits.”

Several differences between magnetite minor and trace element data for magnetite were found for different locations around the world—but Dr Nadoll says the variations are controlled by different formation conditions rather than representing a geographical signature.

“Overall, hydrothermal magnetite from a specific mineral deposit type and igneous magnetite from a specific host rock show a characteristic range of minor and trace element concentrations, which is their compositional signature,” he says.

“Magnetite from magnesian skarn deposits in the US will have similar compositional signatures to magnetite from the same deposit type in Indonesia.”

Following on from the research, Dr Nadoll says magnetite from glacigenic or stream sediments, or from regolith cover, can serve as an indicator for mineral exploration.

Note : The above story is based on materials provided by Science Network WA

First-ever 3D image created of the structure beneath Sierra Negra volcano

This illustration shows the plumbing system beneath the Sierra Negra volcano. Credit: Cynthia Ebinger, University of Rochester

The Galápagos Islands are home to some of the most active volcanoes in the world, with more than 50 eruptions in the last 200 years. Yet until recently, scientists knew far more about the history of finches, tortoises, and iguanas than of the volcanoes on which these unusual fauna had evolved.

Now research out of the University of Rochester is providing a better picture of the subterranean plumbing system that feeds the Galápagos volcanoes, as well as a major difference with another Pacific Island chain — the Hawaiian Islands. The findings have been published in the Journal of Geophysical Research: Solid Earth.

“With a better understanding of what’s beneath the volcanoes, we’ll now be able to more accurately measure underground activity,” said Cynthia Ebinger, a professor of earth and environmental sciences. “That should help us better anticipate earthquakes and eruptions, and mitigate the hazards associated with them.”

Ebinger’s team, which included Mario Ruiz from the Instituto Geofisico Escuela Politecnica Nacional in Quito, Ecuador, buried 15 seismometers around Sierra Negra, the largest and most active volcano in the Galápagos. The equipment was used to measure the velocity and direction of different sound waves generated by earthquakes as they traveled under Sierra Negra. Since the behavior of the waves varies according to the temperature and types of material they’re passing through, the data collected allowed the researchers to construct a 3D image of the plumbing system beneath the volcano, using a technique similar to a CAT-scan.

Five kilometers down is the beginning of a large magma chamber lying partially within old oceanic crust that had been buried by more than 8 km of eruptive rock layers. And the oceanic crust has what appears to be a thick underplating of rock formed when magma that was working its way toward the surface became trapped under the crust and cooled — very much like the processes that occur under the Hawaiian Islands.

The researchers found that the Galápagos had something else in common with the Hawaiian Islands. Their data suggest the presence of a large chamber filled with crystal-mush magma — cooled magma that includes crystallized minerals.

The Galápagos Islands formed from a hotspot of magma located in an oceanic plate — called Nazca — about 600 miles of Ecuador, in a process very similar to how the Hawaiian Islands were created. Magma rising from the hotspot eventually hardened into an island. Then, as the Nazca plate inched its way westward, new islands formed in the same manner, resulting in the present-day Galápagos Archipelago.

While there are several similarities between the two island chains, Ebinger uncovered a major difference. The older volcanos in the Hawaiian Islands are dormant, because they’ve moved away from the hotspot that provided the source of magma. In the Galápagos, the volcanoes are connected to the same plumbing system. By studying satellite views of the volcanoes, Ebinger and colleagues noticed that, as the magma would sink in one, it would rise in a different volcano — indicating that that some of the youngest volcanoes had magma connections, even if those connections were temporary.

“Not only do we have a better understanding of the physical properties of Sierra Negra,” said Ebinger, “we have increased out knowledge of island volcano systems, in general.”

The Galápagos Islands are home to some of the most active volcanoes in the world, with more than 50 eruptions in the last 200 years. Yet until recently, scientists knew far more about the history of finches, tortoises, and iguanas than of the volcanoes on which these unusual fauna had evolved.

Now research out of the University of Rochester is providing a better picture of the subterranean plumbing system that feeds the Galápagos volcanoes, as well as a major difference with another Pacific Island chain — the Hawaiian Islands.

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

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