Impact craters reveal one of the most spectacular geologic process known to man. During the past 3.5 billion years, it is estimated that more than 80 bodies, larger than the dinosaur-killing asteroid that struck the Yucatan Peninsula 66 million years ago, have bombarded Earth. However, tectonic processes, weathering, and burial quickly obscure or destroy craters. For example, if Earth weren’t so dynamic, its surface would be heavily cratered like the Moon or Mercury.
Work by B.C. Johnson and T.J. Bowling predicts that only about four of the craters produced by these impacts could persist until today, and geologists have already found three such craters (larger than 170 km in diameter). Their study, published online for Geology on 22 May 2014, indicates that craters on Earth cannot be used to understand Earth’s bombardment history.
Johnson and Bowling write, however, that layers of molten rock blasted out early in the impact process may act as better records of impacts—even after the active Earth has destroyed the source craters. The authors suggest that searches for these impact ejecta layers will be more fruitful for determining how many times Earth was hit by big asteroids than searches for large craters.
Reference:
B.C. Johnson and T.J. Bowling. Where have all the craters gone? “Earth’s bombardment history and the expected terrestrial cratering record.” Geology, G35754.1, first published on May 22, 2014, DOI: 10.1130/G35754.1
Note : The above story is based on materials provided by Geological Society of America
The Slave River is a Canadian river that flows from Lake Athabasca in northeastern Alberta and empties into Great Slave Lake in the Northwest Territories. The river’s name is thought to derive from the name for the Slavey group of the Dene First Nations, Deh Gah Got’ine, in the Athabaskan language, and has nothing to do with slavery. The Chipewyan had displaced other native people from this region.
Course
The Slave River originates in the Peace-Athabasca Delta, at the forks of Peace River and Riviere Des Roches, which drains the Athabasca River and Lake Athabasca. The Slave River flows north into the Northwest Territories and into the Great Slave Lake north of Fort Resolution. From there the water reaches the Arctic Ocean through the Mackenzie River.The river is 434 km in length and has a cumulative drainage area of 616,400 km².
Portage and Navigation
Prior to the extension of railway service to Hay River, Northwest Territories, a river port on Great Slave Lake, cargo shipment on the Slave River was an important transport route. Locally built wooden vessels were navigating the river into the late 19th Century. The rapids required a portage of 16 miles (26 km). Tractors were imported from Germany to assist in hauling goods around the rapids. Tugs and barges of the Northern Transportation Company’s “Radium Line” were constructed in the south and disassembled. The parts were then shipped by rail to Waterways, Alberta, shipped by barge to the portage, and portaged to the lower river for reassembly, where they could navigate most of the rest of the extensive Mackenzie River basin.
Tributaries
Peace-Athabasca Delta
Athabasca River
Lake Athabasca
Riviere Des Roches
Chilloneys Creek
Revillon Coupe
Dempsey Creek
Peace River
Scow Channel
Murdock Creek
Darough Creek
Powder Creek
La Butte Creek
Hornaday River
Salt River
Little Buffalo River
Note : The above story is based on materials provided by Wikipedia
Chemical Formula: PbFe3+4As3+10O22 Locality: In a boulder of ore found at Tsumeb, Namibia. Name Origin: Named for mineral dealers Ludlow Smith and Locke Key, who discovered the mineral.
History
Discovery date : 1970 Town of Origin : TSUMEB Country of Origin : NAMIBIE
Optical properties
Refractive Index: from 1,96 to 2,12
Physical Properties
Cleavage: {011} Perfect, {021} Perfect Color: Reddish brown. Density: 4.37 – 4.4, Average = 4.38 Hardness: 1.5-2 – Talc-Gypsum Luster: Subadamantine Streak: pale brown
Seafloor topography in the Malaysia Airlines flight MH370 search area. Dashed lines approximate the search zone for sonar pings emitted by the flight data recorder and cockpit voice recorder popularly called black boxes. The first sonar contact (black circle) was reportedly made by a Chinese vessel on the east flank of Batavia Plateau (B), where the shallowest point in the area (S) is at an estimated depth of 1637 meters. The next reported sonar contact (red circle) was made by an Australian vessel on the north flank of Zenith Plateau (Z). The deepest point in the area (D) lies in the Wallaby-Zenith Fracture Zone at an estimated depth of 7883 meters. The Wallaby Plateau (W) lies to the east of the Zenith Plateau. The shallowest point in the entire area shown here is on Broken Ridge (BR). Deep Sea Drilling Project (DSDP) site 256 is marked by a gray dot. The inset in the top left shows the area’s location to the west of Australia. Seafloor depths are from the General Bathymetric Chart of the Oceans [2010]. Credit: Walter H.F. Smith and Karen M. MarksA new illustration of the seafloor, created by two of the world’s leading ocean floor mapping experts that details underwater terrain where the missing Malaysia Airlines flight might be located, could shed additional light on what type of underwater vehicles might be used to find the missing airplane and where any debris from the crash might lie.
The seafloor topography map illustrates jagged plateaus, ridges and other underwater features of a large area underneath the Indian Ocean where search efforts have focused since contact with Malaysia Airlines flight MH370 was lost on March 8. The image was published today in Eos, the weekly newspaper of the Earth and space sciences, published by the American Geophysical Union.
The new illustration of a 2,000 kilometer by 1,400 kilometer (1,243 miles by 870 miles) area where the plane might be shows locations on the seafloor corresponding to where acoustic signals from the airplane’s black boxes were reportedly detected at the surface by two vessels in the area. It also shows the two plateaus near where these “pings” were heard.
It points out the deepest point in the area: 7,883 meters (about five miles) underneath the sea in the Wallaby-Zenith Fracture Zone — about as deep as 20 Empire State buildings stacked top to bottom. Undersea mountains and plateaus rise nearly 5,000 meters (about three miles) above the deep seafloor, according to the map.
The illustration, designated as Figure 1 of the Eos article, was created by Walter H.F. Smith and Karen M. Marks, both of the National Oceanic and Atmospheric Administration’s Laboratory for Satellite Altimetry in College Park, Maryland, and the former and current chairs, respectively, of the Technical Sub-Committee on Ocean Mapping of the General Bathymetric Chart of the Oceans, or GEBCO. GEBCO is an international organization that aims to provide the most authoritative publicly available maps of the depths and shapes of the terrain underneath the world’s oceans.
Satellite altimetry has made it possible to depict the topography of vast regions of the seafloor that would otherwise have remained unmapped, Smith said. To illustrate the topography of the search area, Smith and Marks used publicly available data from GEBCO and other bathymetric models and data banks, along with information culled from news reports.
Smith said the terrain and depths shown in the map could help searchers choose the appropriate underwater robotic vehicles they might use to look for the missing plane. Knowing the roughness and shape of the ocean floor could also help inform models predicting where floating debris from the airplane might turn up.
Smith cautions that the new illustration is not a roadmap to find the missing airplane. Nor does the map define the official search area for the aircraft, he added.
“It is not ‘x marks the spot’,” Smith said of their map. “We are painting with a very, very broad brush.”
Search efforts for the missing airplane have focused on an area of the southern Indian Ocean west of Australia where officials suspect that the plane crashed after it veered off course. After an initial air and underwater search failed to find any trace of the airplane, authorities announced this month that they will expand the search area and also map the seabed in the area.
Smith pointed out that the search for the missing plane is made more difficult because so little is understood about the seafloor in this part of the Indian Ocean. In the southeast Indian Ocean, only 5 percent of the ocean bottom has been measured by ships with echo soundings. Knowledge of the rest of the area comes from satellite altimetry, which provides relatively low-resolution mapping compared to ship-borne methods.
“It is a very complex part of the world that is very poorly known,” Smith said.
A lack of good data about Earth’s seafloors not only hinders search efforts, it also makes it harder for scientists to accurately model the world’s environment and climate, Smith noted. Today, our knowledge of our planet’s undersea topography is “vastly poorer than our knowledge of the topographies of Earth’s Moon, Mars and Venus,” Smith and Marks write in Eos. This is because these other planetary bodies have no oceans, making their surfaces relatively easy to sense from space.
Smith said he hoped that “the data collected during the search for MH370 will be contributed to public data banks and will be a start of greater efforts to map Earth’s ocean floor.”
Note : The above story is based on materials provided by American Geophysical Union.
For many years geophysicists have argued over the perplexing mystery regarding the amount of silicon in the Earth’s mantle that is thought to have arrived there via impacts with asteroids.
The problem is that tests done to determine the composition of the mantel have found that there appears to be less silicon in it proportionally, than there is in asteroids. Now new research by a Japanese team suggests that the lowest section of the Earth’s mantle has more silicon in it than does the upper parts, perhaps solving the mystery. They have described their work in their paper published in the journal Nature.
To help clarify what lies far beneath our feet, geophysicists have subdivided the Earth’s mantle into three broad sections: the upper, middle and lower mantle. The upper mantle describes the crust and approximately 400 km below. The middle is about 250 km thick and the lower goes to about 2,900 km in depth.
The upper mantle is far easier to study of course, due to its proximity and thus the proportion of silicon in it is well understood. Not so well understood has been the composition of the middle and lower mantles. To study them, researches generally use seismic data recorded by sending shockwaves into the ground, but doing so thus far, has led more often to speculation than good science.
To get a better handle on what is happening so far beneath the Earth’s surface the Japanese team took a different approach; instead of trying to measure the lower mantle itself, they sought to recreate it in a lab where it could be measured much more easily. To do that, they mixed the ingredients (mainly silicate perovskite and ferropericlase) they believe exist in the lower mantel and placed them in a pressure chamber. There the sample was subjected to different pressure levels consistent with current theories describing the differing degrees of pressure at different levels of the mantle. They then applied the same seismic tests normally done on the real mantle. In so doing, they have come to believe that the lower mantle has a volume that is approximately 93% silicate perovskite, which when compared with data describing the upper crust gives an average amount of silicon for the entire mantle that is very nearly equal to that found in asteroids. Thus, the mystery, they say is solved.
Chemical Formula: (Fe,Mn,Mg)3(PO4)2·4H2O Locality: Wheal Jane, Kea, near Truro, Cornwall, England, UK. Name Origin: Named for Henry Ludlam (1824-1880), English mineralogist and collector.
Ludlamite is a rare phosphate mineral with formula: (Fe,Mn,Mg)3(PO4)2·4H2O
It was first described in 1877 for an occurrence in Wheal Jane mine in Cornwall, England and named for English mineralogist Henry Ludlam (1824–1880).
History
Discovery date : 1877 Town of Origin : WHEAL JANE (MINE), TRURO, CORNOUAILLES Country of Origin: ANGLETERRE
Optical properties
Optical and misc. Properties : Transparent to Translucent Refractive Index: from 1,65 to 1,69 Axial angle 2V : 82°
Physical Properties
Cleavage: {001} Perfect, {100} Indistinct Color: Apple green, Colorless, Green, Greenish white, Light green. Density: 3.15 Diaphaneity: Transparent to Translucent Hardness: 3.5 – Copper Penny Luster: Vitreous (Glassy) Streak: white
During the earliest stages of the Earth’s formation, the planet’s mantle may have taken the form of a giant magma ocean, being fully or partially molten all the way down to the core-mantle boundary. Though today mantle material is predominantly solid, some scientists suggest that regions of anomalously low seismic wave velocity deep within the mantle, known as ultralow velocity zones (ULVZs), may be indicative of a remnant magma ocean or of partial melting of minerals near the core-mantle boundary. To understand how the early mantle solidified, or whether modern melt could be the source of ULVZs, scientists need to know how various minerals and melts behave under the extreme conditions found near the center of the Earth.
Through the use of various techniques, Thomas et al.analyzed how the density of molten fayalite—an iron-bearing silicate mineral—behaved under pressures up to 161 gigapascals, surpassing those at the core-mantle boundary.
The research adds to previous investigations into the equation of state of fayalite, an expression describing how the material’s density responds to changes in temperature and pressure. The authors find that iron-bearing fayalite behaves similarly to nonferrous silicate liquids during compression and heating.
Based on the measured equation of state, and on the known behavior of other silicate liquids, the authors suggest that the solidification of the Earth’s early mantle would have started near the core-mantle boundary or in the lower mantle.
Based on the current research, the authors are unable to determine whether ultralow velocity zones are necessarily caused by partial melting of the mantle material. They did, however, identify a potential set of liquid compositions that would be gravitationally stable if present.
Researchers established the age of the various rocks on Christmas Island at the time they were erupted, and established the position of the island through time. Credit: Peter McKiernan
Geological samples from Christmas Island have been analysed by a West Australian scientist, giving valuable insight into its unique volcanic history.
Curtin University geochronologist Dr Fred Jourdan says while continents are often the subject of geological investigation, ocean geology is less studied and the results of the Christmas Island study adds important information to the field.
The report he co-authored has been published in Gondwana Research.
It describes the Christmas Island area as an extensive zone of volcanism in the north-east Indian Ocean, consisting of numerous submerged seamounts and flat topped guyots.
It explains the island has experienced multiple episodes of volcanism that are exposed sporadically along its coastline.
It is the only island in the region to show intraplate volcanism in the form of basaltic rocks that are exposed above sea level.
Dr Jourdan says the project was a collaboration with Macquarie University. Samples were collected by a student from Macquarie University and tested at Curtin University using 40Ar/39Ar geochronology and paleomagnetism.
Dr Jourdan says this is where the ‘real science’ of finding their origin began.
“What we did was two things; we established the age of the various rocks on the island at the time they were erupted, and we established the position of the island through time,” he says.
“We needed to look at where it was before, to understand why there is volcanic activity at all—is it random or related to something in particular?
“We measured two different ages but we know, comparing it to other seamounts, there are in fact three periods of volcanic activity.
Three stages of Christmas Island volcanic activity
“The oldest happened when Australia and India separated and the rock left behind melted to create a seamount—that was the first volcanic activity, although we didn’t sample this and at this time, the island was much further south than it is now.
“The second, happened between 43 and 37 million years ago—it happened when the continent moved north above a hot zone in the mantle.
“Nothing happened for 30 million years until, in its northward movement toward the European-Asian plate; the plate cracked five million years ago and the magma could easily rise through the cracks.”
Dr Jourdan says similar low volume intraplate volcanism had previously been observed at similar tectonic settings to the Japan and Tonga trench.
“…We put forward the Indo Australian plate subduction setting as a likely candidate for this phase of introceanic volcanism.”
More information:
Rajat Taneja, Craig O’Neill, Mark Lackie, Tracy Rushmer, Phil Schmidt, Fred Jourdan, “40Ar/39Ar geochronology and the paleoposition of Christmas Island (Australia), Northeast Indian Ocean,” Gondwana Research, Available online 27 April 2014, ISSN 1342-937X, dx.doi.org/10.1016/j.gr.2014.04.004.
Note : The above story is based on materials provided by Science Network WA
Chemical Formula: FeAs2 Locality: Lölling, Hüttenberg, Carinthia, Austria Name Origin: Named after its locality.
Loellingite, also spelled löllingite, is an iron arsenide mineral with formula FeAs2. It is often found associated with arsenopyrite (FeAsS) from which it is hard to distinguish. Cobalt, nickel and sulfur substitute in the structure. The orthorhombic lollingite group includes the nickel iron arsenide rammelsbergite and the cobalt iron arsenide safflorite. Leucopyrite is an old synonym for loellingite.
It forms opaque silvery white orthorhombic prismatic crystals often exhibiting crystal twinning. It also occurs in anhedral masses and tarnishes on exposure to air. It has a Mohs hardness of 5.5 to 6 and a quite high specific gravity of 7.1 to 7.5. It becomes magnetic after heating.
Loellingite was first described in 1845 at the Lölling district in Carinthia, Austria, for which it was named.
It occurs in mesothermal ore deposits associated with skutterudite, native bismuth, nickeline, nickel-skutterudite, siderite and calcite. It has also been reported from pegmatites.
History
Discovery date : 1845 Town of Origin : MINE WOLFBAUER, LOLLING, HUTTENBERG, CARINTHIE Country of Origin: AUTRICHE
Optical properties
Optical and misc. Properties: Opaque Reflective Power: 51,7-54,2% (580)
Physical Properties
Cleavage: {001} Distinct Color: Silvery white, Tarnish gray. Density: 7.1 – 7.7, Average = 7.4 Diaphaneity: Opaque Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern. Hardness: 5 – Apatite Luminescence: Non-fluorescent. Luster: Metallic Magnetism: Magnetic after heating Streak: grayish black
New research, published this week, has provided scientists with greater insight into the climatic changes happening in the upper atmosphere. Scientists found that changes in the Earth’s magnetic field are more relevant for climatic changes in the upper atmosphere (about 100-500 km above the surface) than previously thought. Understanding the cause of long-term change in this area helps scientists to predict what will happen in the future. This has key implications for life back on earth.
A good understanding of the long-term behaviour of the upper atmosphere is essential; it affects a lot of satellite-based technology, such as global navigation systems and high-frequency radio communication systems. Some satellites even operate within the upper atmosphere itself.
The increase in atmospheric CO2 concentration has been thought to be the main cause of climatic changes at these high altitudes. This study suggests that magnetic field changes that have taken place over the past century are as important.
Both increasing levels of CO2 and changes in the Earth’s magnetic field affect the upper atmosphere, including its charged portion, also known as the ionosphere. Dr. Ingrid Cnossen from the British Antarctic Survey used computer simulations to compare the effects of these two factors over the past century.
While CO2 causes heat to be trapped in the lower atmosphere, it actually cools the upper atmosphere. The simulations show that the increase in CO2 concentration over the past 100 years has caused the upper atmosphere, at around 300 km altitude, to cool by around 8 degrees. At the same altitude, changes in the Earth’s magnetic field caused a similar amount of cooling over parts of North America, but caused a warming over other parts of the world, with the strongest warming, of up to 12 degrees, located over Antarctica.
Dr. Ingrid Cnossen said: “Computer simulations are a very important tool in understanding the causes of climate change at high altitudes. We still can’t explain all of the long-term trends that have been observed, but it helps that we now know how important the magnetic field is.”
The new simulations also indicate that rising CO2 levels have caused the densest part of the ionosphere to lower by about 5 km globally. Changes in the Earth’s magnetic field can cause much larger changes, but they are very dependent on location and can be either positive or negative; over the southern Atlantic Ocean a decrease in height of up to 50 km was found, while an increase in height of up to 20 km was found over western Africa.
The findings are published in the Journal of Space Weather and Space Climate.
Note : The above story is based on materials provided by British Antarctic Survey
An Italian astronomer in the 19th century first described them as ‘canali’ – on Mars’ equatorial region, a conspicuous net-like system of deep gorges known as the Noctis Labyrinthus is clearly visible. The gorge system, in turn, leads into another massive canyon, the Valles Marineris, which is 4,000 km long, 200 km wide and 7 km deep. Both of these together would span the US completely from east to west.
As these gorges, when observed from orbit, resemble terrestrial canyons formed by water, most researchers assumed that immense flows of water must have carved the Noctis Labyrinthus and the Valles Marineris into the surface of Mars. Another possibility was that tectonic activity had created the largest rift valley on a planet in our solar system.
Lava flows caused the gorges
These assumptions were far from the mark, says Giovanni Leone, a specialist in planetary volcanism in the research group of ETH professor Paul Tackley. Only lava flows would have had the force and mass required to carve these gigantic gorges into the surface of Mars. The study was recently published in the Journal of Volcanology and Geothermal Research.
In recent years, Leone has examined intensively the structure of these canyons and their outlets into the Ares Vallis and the Chryse Planitia, a massive plain on Mars’ low northern latitude. He examined thousands of high-resolution surface images taken by numerous Mars probes, including the latest from the Mars Reconnaissance Orbiter, and which are available on the image databases of the US Geological Survey.
No discernible evidence of erosion by water
His conclusion is unequivocal: “Everything that I observed on those images were structures of lava flows as we know them on Earth,” he emphasises. “The typical indicators of erosion by water were not visible on any of them.” Leone therefore does not completely rules out water as final formative force. Evidence of water, such as salt deposits in locations where water evaporated from the ground or signs of erosion on the alluvial fans of the landslides, are scarce but still existing. “One must therefore ask oneself seriously how Valles Marineris could have been created by water if one can not find any massive and widespread evidence of it.” The Italian volcanologist similarly could find no explanation as to where the massive amounts of water that would be required to form such canyons might have originated.
Source region of lava flows identified
The explanatory model presented by Leone in his study illustrates the formation history from the source to the outlet of the gorge system. He identifies the volcanic region of Tharsis as the source region of the lava flows and from there initial lava tubes stretched to the edge of the Noctis Labyrinthus. When the pressure from an eruption subsided, some of the tube ceilings collapsed, leading to the formation of a chain of almost circular holes, the ‘pit chains’.
When lava flowed again through the tubes, the ceilings collapsed entirely, forming deep V-shaped troughs. Due to the melting of ground and rim material, and through mechanical erosion, the mass of lava carved an ever-deeper and broader bed to form canyons. The destabilised rims then slipped and subsequent lava flows carried away the debris from the landslides or covered it. “The more lava that flowed, the wider the canyon became,” says Leone.
Leone supported his explanatory model with height measurements from various Mars probes. The valleys of the Noctis Labyrinthus manifest the typical V-shape of ‘young’ lava valleys where the tube ceilings have completely collapsed. The upper rims of these valleys, however, have the same height. If tectonic forces had been at work, they would not be on the same level, he says. The notion of water as the formative force, in turn, is undermined by the fact that it would have taken tens of millions of cubic kilometres of water to carve such deep gorges and canyons. Practically all the atmospheric water of all the ages of Mars should have been concentrated only on Labyrinthus Noctis. Moreover, the atmosphere on Mars is too thin and the temperatures too cold. Water that came to the surface wouldn’t stay liquid, he notes: “How could a river of sufficient force and size even form?”
Life less likely
Leone’s study could have far-reaching consequences. “If we suppose that lava formed the Noctis Labyrinthus and the Valles Marineris, then there has always been much less water on Mars than the research community has believed to date,” he says. Mars received very little rain in the past and it would not have been sufficient to erode such deep and large gorges. He adds that the shallow ocean north of the equator was probably much smaller than imagined – or hoped for; it would have existed only around the North Pole. The likelihood that life existed, or indeed still exists, on Mars is accordingly much lower.
Leone can imagine that the lava tubes still in existence are possible habitats for living organisms, as they would offer protection from the powerful UV rays that pummel the Martian surface. He therefore proposes a Mars mission to explore the lava tubes. He considers it feasible to send a rover through a hole in the ceiling of a tube and search for evidence of life. “Suitable locations could be determined using my data,” he says.
Swimming against the current
With his study, the Italian is swimming against the current and perhaps dismantling a dogma in the process. Most studies of the past 20 years have been concerned with the question of water on Mars and how it could have formed the canyons. Back in 1977, a researcher first posited the idea that the Valles Marineris may have been formed by lava, but the idea failed to gain traction. Leone says this was due to the tunnel vision that the red planet engenders and the prevailing mainstream research. The same story has been told for decades, with research targeted to that end, without achieving a breakthrough. Leone believes that in any case science would only benefit in considering other approaches. “I expect a spirited debate,” he says. “But my evidence is strong.”
Note : The above story is based on materials provided by ETH Zurich
Chemical Formula: Cu2Al(AsO4)(OH)4·4H2O Locality: Wheal Gorland, Gwennap, Cornwall, England, UK Name Origin: From the Greek, liros – “pale” and konia – “powder.”
Liroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula Cu2Al(AsO4)(OH)4·4H2O. It is a vitreous monoclinic mineral, colored bright blue to green, often associated with malachite, azurite, olivenite, and clinoclase. It is quite soft, with a Mohs hardness of 2 – 2.5, and has a specific gravity of 2.9 – 3.0.
It was first identified in 1825 in the tin and copper mines of Devon and Cornwall, England. Although it remains quite rare it has subsequently been identified in a variety of locations including France, Germany, Australia, New Jersey and California.
The type locality for Liroconite is Wheal Gorland in St Day, Cornwall in the United Kingdom.
It occurs as a secondary mineral in copper deposits in association with olivenite, chalcophyllite, clinoclase, cornwallite, strashimirite, malachite, cuprite and limonite.
History
Discovery date : 1825 Town of Origin: REDRUTH ET ST. DAY, CORNOUAILLES Country of Origin : ANGLETERRE
Optical properties
Optical and misc. Properties: Transparent to Translucent Refractive Index: from 1,61 to 1,67 / de 1,61 à 1,67 Axial angle 2V : ~72°
Physical Properties
Cleavage: {100} Indistinct, {011} Indistinct Color: Light blue, Green, Sky blue, Verdigris green. Density: 2.9 – 3, Average = 2.95 Diaphaneity: Transparent to Translucent Fracture: Sub Conchoidal – Fractures developed in brittle materials characterized by semi-curving surfaces. Hardness: 2-2.5 – Gypsum-Finger Nail Luminescence: Non-fluorescent. Luster: Vitreous – Resinous Streak: light blue
Crystals of putnisite (purple) . Image credit: P. Elliott et al.
The new mineral is named putnisite after Drs Christine and Andrew Putnis from the University of Münster, Germany, for their outstanding contributions to mineralogy.
Putnisite occurs as isolated pseudocubic crystals, up to 0.5 mm in diameter, and is associated with quartz and a near amorphous Cr silicate.
It is translucent, with a pink streak and vitreous lustre. It is brittle and shows one excellent and two good cleavages parallel to {100}, {010} and {001}.
“What defines a mineral is its chemistry and crystallography. By x-raying a single crystal of mineral you are able to determine its crystal structure and this, in conjunction with chemical analysis, tells you everything you need to know about the mineral,” explained Dr Elliott, who, along with colleagues, described putnisite in the Mineralogical Magazine.
“Most minerals belong to a family or small group of related minerals, or if they aren’t related to other minerals they often are to a synthetic compound – but putnisite is completely unique and unrelated to anything.”
Putnisite combines the elements strontium, calcium, chromium, sulfur, carbon, oxygen and hydrogen: SrCa4Cr83+(CO3)8SO4(OH)16•25H2O
The mineral has a Mohs hardness of 1.5–2, a measured density of 2.20 g/cm3 and a calculated density of 2.23 g/cm3. It was discovered during prospecting by a mining company in Western Australia.
“Nature seems to be far cleverer at dreaming up new chemicals than any researcher in a laboratory,” Dr Elliott concluded.
Reference::
P. Elliott et al. 2014. Putnisite, SrCa4Cr83+(CO3)8SO4(OH)16•25H2O, a new mineral from Western Australia: description and crystal structure. Mineralogical Magazine, vol. 78, no. 1, pp. 131-144; DOI: 10.1180/minmag.2014.078.1.10
Note : The above story is based on materials provided by Natali Anderson.
Image showing the remnants of a crater that UAlberta researchers theorize was left by a massive meteorite strike sometime in the last 70 million years. Colour variation shows metres above sea level.
The discovery of an ancient ring-like structure in southern Alberta suggests the area was struck by a meteorite large enough to leave an eight-kilometre-wide crater, producing an explosion strong enough to destroy present-day Calgary, say researchers from the Alberta Geological Survey and University of Alberta.
The first hints about the impact site near the southern Alberta hamlet of Bow City were discovered by a geologist with the Alberta Geological Survey and studied by a U of A team led by Doug Schmitt, Canada Research Chair in Rock Physics.
Time and glaciers have buried and eroded much of the evidence, making it impossible at this point to say with full certainty the ring-like structure was caused by a hypervelocity meteorite impact, but that’s what seismic and geological evidence strongly suggests, said Schmitt, a professor in the Faculty of Science and co-author of a new paper about the discovery.
“We know that the impact occurred within the last 70 million years, and in that time about 1.5 km of sediment has been eroded. That makes it really hard to pin down and actually date the impact.”
Erosion has worn away all but the “roots” of the crater, leaving a semicircular depression eight kilometres across with a central peak. Schmitt says that when it formed, the crater likely reached a depth of 1.6 to 2.4 km—the kind of impact his graduate student Wei Xie calculated would have had devastating consequences for life in the area.
“An impact of this magnitude would kill everything for quite a distance,” he said. “If it happened today, Calgary (200 km to the northwest) would be completely fried and in Edmonton (500 km northwest), every window would have been blown out. Something of that size, throwing that much debris in the air, potentially would have global consequences; there could have been ramifications for decades.”
The impact site was first discovered in 2009 by geologist Paul Glombick, who at the time was working on a geological map of the area for the Alberta Geological Survey, focusing on the shallow subsurface, between zero and 500 metres in depth. Glombick relied on existing geophysical log data from the oil and gas industry when he discovered a bowl-shaped structure. After checking maps of the area dating back to the 1940s, he found evidence of faulting at the surface.
The Alberta Geological Survey contacted the U of A and Schmitt to explore further, peeking into the earth by analyzing seismic data donated by industry. Schmitt’s student, Todd Brown, later confirmed a crater-like structure.
For Glombick, who earned his bachelor’s degree and PhD in geology from the U of A, contributing to such a historic find was a “pretty cool” departure from his regular duties of mapping rock and layers in the shallow subsurface.
“It’s exciting to come across a structure like this. It highlights there’s still a fair amount of unknowns in the shallow subsurface,” he said, noting the oil and gas industry’s geological interests focus deeper underground. “It’s nice to be able to contribute something to the geology of Alberta.”
The research team’s paper about the discovery was published in the journal Meteoritics & Planetary Science in an early online release.
Map:
Note : The above story is based on materials provided by University of Alberta
Chemical Formula: Co2+Co3+2S4 Locality: Bastnäs mines, Riddarhyttan, Västmanland, Sweden. Name Origin: Named after the Swedish botanist, C. Linne (1707-1778).Linnaeite is a cobalt sulfide mineral with the composition Co2+Co3+2S4. It was discovered in 1845 in Västmanland, Sweden, and was named to honor Carl Linnaeus (1707–1778).Linnaeite forms a series with polydymite, Ni+2Ni+32S4. Linnaeite is found in hydrothermal veins with other cobalt and nickel sulfides in many localities around the world
History
Discovery date : 1845 Town of Origin : MINE BASTNAS, RIDDERHYTTAN Country of Origin: SUEDE
Optical properties
Optical and misc. Properties : Opaque Reflective Power: 44,7% (580)
An eroding bluff on the US Great Plains reveals a buried, carbon-rich layer of fossil soil. A team of researchers led by UW-Madison Assistant Professor of geography Erika Marin-Spiotta has found that buried fossil soils contain significant amounts of carbon and could contribute to climate change as the carbon is released through human activities such as mining, agriculutre and deforestation. Credit: Jospeh Mason
Soils that formed on the Earth’s surface thousands of years ago and that are now deeply buried features of vanished landscapes have been found to be rich in carbon, adding a new dimension to our planet’s carbon cycle.
The finding, reported today in the journal Nature Geoscience, is significant as it suggests that deep soils can contain long-buried stocks of organic carbon which could, through erosion, agriculture, deforestation, mining and other human activities, contribute to global climate change.
“There is a lot of carbon at depths where nobody is measuring,” says Erika Marin-Spiotta, a University of Wisconsin-Madison assistant professor of geography and the lead author of the new study. “It was assumed that there was little carbon in deeper soils. Most studies are done in only the top 30 centimeters. Our study is showing that we are potentially grossly underestimating carbon in soils.”
The soil studied by Marin-Spiotta and her colleagues, known as the Brady soil, formed between 15,000 and 13,500 years ago in what is now Nebraska, Kansas and other parts of the Great Plains. It lies up to six-and-a- half meters below the present-day surface and was buried by a vast accumulation of windborne dust known as loess beginning about 10,000 years ago, when the glaciers that covered much of North America began to retreat.
The region where the Brady soil formed was not glaciated, but underwent radical change as the Northern Hemisphere’s retreating glaciers sparked an abrupt shift in climate, including changes in vegetation and a regime of wildfire that contributed to carbon sequestration as the soil was rapidly buried by accumulating loess.
“Most of the carbon (in the Brady soil) was fire derived or black carbon,” notes Marin-Spiotta, whose team employed an array of new analytical methods, including spectroscopic and isotopic analyses, to parse the soil and its chemistry. “It looks like there was an incredible amount of fire.”
The team led by Marin-Spiotta also found organic matter from ancient plants that, thanks to the thick blanket of loess, had not fully decomposed. Rapid burial helped isolate the soil from biological processes that would ordinarily break down carbon in the soil.
Such buried soils, according to UW-Madison geography Professor and study co-author Joseph Mason, are not unique to the Great Plains and occur worldwide.
The work suggests that fossil organic carbon in buried soils is widespread and, as humans increasingly disturb landscapes through a variety of activities, a potential contributor to climate change as carbon that had been locked away for thousands of years in arid and semiarid environments is reintroduced to the environment.
The element carbon comes in many forms and cycles through the environment – land, sea and atmosphere – just as water in various forms cycles through the ground, oceans and the air. Scientists have long known about the carbon storage capacity of soils, the potential for carbon sequestration, and that carbon in soil can be released to the atmosphere through microbial decomposition.
The deeply buried soil studied by Marin-Spiotta, Mason and their colleagues, a one-meter-thick ribbon of dark soil far below the modern surface, is a time capsule of a past environment, the researchers explain. It provides a snapshot of an environment undergoing significant change due to a shifting climate. The retreat of the glaciers signaled a warming world, and likely contributed to a changing environment by setting the stage for an increased regime of wildfire.
“The world was getting warmer during the time the Brady soil formed,” says Mason. “Warm-season prairie grasses were increasing and their expansion on the landscape was almost certainly related to rising temperatures.”
The retreat of the glaciers also set in motion an era when loess began to cover large swaths of the ancient landscape. Essentially dust, loess deposits can be thick—more than 50 meters deep in parts of the Midwestern United States and areas of China. It blankets large areas, covering hundreds of square kilometers in meters of sediment.
This shows a visualization of vibrations inside the Merapi volcano (island of Java) computed with the earthquake simulation software SeisSol. Credit: Alex Breuer (TUM) / Christian Pelties (LMU)
Geophysicists use the SeisSol earthquake simulation software to investigate rupture processes and seismic waves beneath the Earth’s surface. Their goal is to simulate earthquakes as accurately as possible to be better prepared for future events and to better understand the fundamental underlying mechanisms. However, the calculations involved in this kind of simulation are so complex that they push even super computers to their limits.
In a collaborative effort, the workgroups led by Dr. Christian Pelties at the Department of Geo and Environmental Sciences at LMU and Professor Michael Bader at the Department of Informatics at TUM have optimized the SeisSol program for the parallel architecture of the Garching supercomputer “SuperMUC”, thereby speeding up calculations by a factor of five.
Using a virtual experiment they achieved a new record on the SuperMUC: To simulate the vibrations inside the geometrically complex Merapi volcano on the island of Java, the supercomputer executed 1.09 quadrillion floating point operations per second. SeisSol maintained this unusually high performance level throughout the entire three hour simulation run using all of SuperMUC’s 147,456 processor cores.
Complete parallelization
This was possible only following the extensive optimization and the complete parallelization of the 70,000 lines of SeisSol code, allowing a peak performance of up to 1.42 petaflops. This corresponds to 44.5 percent of Super MUC’s theoretically available capacity, making SeisSol one of the most efficient simulation programs of its kind worldwide.
“Thanks to the extreme performance now achievable, we can run five times as many models or models that are five times as large to achieve significantly more accurate results. Our simulations are thus inching ever closer to reality,” says the geophysicist Dr. Christian Pelties. “This will allow us to better understand many fundamental mechanisms of earthquakes and hopefully be better prepared for future events.”
The next steps are earthquake simulations that include rupture processes on the meter scale as well as the resultant destructive seismic waves that propagate across hundreds of kilometers. The results will improve the understanding of earthquakes and allow a better assessment of potential future events.
“Speeding up the simulation software by a factor of five is not only an important step for geophysical research,” says Professor Michael Bader of the Department of Informatics at TUM. “We are, at the same time, preparing the applied methodologies and software packages for the next generation of supercomputers that will routinely host the respective simulations for diverse geoscience applications.”
Note : The above story is based on materials provided by Technische Universitaet Muenchen
Chemical Formula: Cu2(PO4)(OH) Locality: Lubietova (German Livethen), Czechoslovakia. Name Origin: Named after its locality.
Libethenite is a rare copper phosphate hydroxide mineral. It forms striking, dark green orthorhombic crystals. It was discovered in 1823 in Ľubietová, Slovakia and is named after the German name of that locality (Libethen).
History
Discovery date : 1823 Town of Origin : L’UBIETOVA (LIBETBANYA) STREDOSLOVENSKY KRAJ Country of Origin : SLOVAQUIE
Optical properties
Optical and misc. Properties : Translucent to subtranslucent Refractive Index : from 1,70 to 1,78 Axial angle 2V : ~90°
Physical Properties
Cleavage: {100} Indistinct, {010} Indistinct Color: Green, Dark green, Blackish green, Light olive green, Dark olive green. Density: 3.6 – 4, Average = 3.8 Diaphaneity: Translucent to subtranslucent Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals. Hardness: 4 – Fluorite Luminescence: Non-fluorescent. Luster: Vitreous – Greasy Streak: light green
GEOMAR researchers specify models for the birth of the youngest world ocean
Pacific, Atlantic and Indian Ocean, with the land masses of the Americas, Europe, Asia, Africa and Australia in between – that’s how we know our earth. From a geologist’s point of view, however, this is only a snapshot. Over the course of the earth’s history, many different continents have formed and split again. In between oceans were created, new seafloor was formed and disappeared again: Plate tectonics is the generic term for these processes.
The Red Sea, where currently the Arabian Peninsula separates from Africa, is one of the few places on earth where the splitting of a continent and the emergence of the ocean can be observed. During a three-year joint project, the Jeddah Transect Project (JTP), researchers at the GEOMAR Helmholtz Centre for Ocean Research Kiel and the King Abdulaziz University (KAU) in Jeddah, Saudi Arabia, have taken a close look at this crack in the earth’s crust by means of seabed mapping, sampling and magnetic modeling. “The findings have shed new light on the early stages of oceanic basins, and they specifically change the school of thought on the Red Sea,” says Dr. Nico Augustin from GEOMAR, lead author of the study. It has now been published in the scientific journal “Earth and Planetary Science Letters”.
It is, and was, undisputed that a continent is stretched and thinned out by volcanic activity before it ruptures and a new ocean basin is formed. The rifting occurs where the greatest stretching takes place. However, the detailed processes during the break-up are debated in research. On the one hand, one needs to better understand the dynamics of our home planet. “On the other hand, most marine oil and gas resources are located near such former fracture zones. This research can therefore also have economic and political implications,” says Professor Colin Devey (GEOMAR), co-author of the study.
Until now, conventional knowledge said that a continent is breaking apart more or less simultaneously along an entire line, and the ocean basin is formed all at once. The Red Sea, however, did not fit into this picture. Here, a model was favored with several smaller fracture zones, lined up one after the other, that would unite gradually, which in turn would lead to a relatively slow emergence of the ocean during a long transition phase. “Our studies show that the Red Sea is not an exception but that it takes its place in line with the other ocean basins,” says Augustin. The previous picture we had of the ocean floor in the Red Sea was simply corrupted by salt glaciers. “The volcanic rocks we recovered are similar to those from other normal mid-ocean ridges,” says co-author Froukje van der Zwan, working on her PhD as part of the JTP.
During the early formation stages of the Red Sea, the area was covered by a very shallow sea that dried up repeatedly. This created thick salt deposits that later on broke apart with the continental crust. Over geologic time periods, salt shows tar-like behavior and begins to flow. “Our new high-resolution seabed maps and magnetic modeling show that the kilometer-thick salt deposits, after the break-up of the Arabian Plate from Africa, flowed like glaciers toward the newly created trench and thus over the oceanic crust due to gravity,” says Augustin. Since these submarine salt glaciers do not cover the rifting zone uniformly over the entire length, the impression of several small fracture zones was created.
The consequences of this discovery are profound: For one, there really seems to be only one single mechanism worldwide for the dispersal of a continent. And secondly, is not yet known how much ocean crust is covered by salt. This questions the previous dating of the opening of the Red Sea. In addition, the volcanically active trench rift zone of the Red Sea, surrounded by salt glaciers, is host of a giant sink filled with a very hot and very salty solution. “Since the sediment in the salt solution is rich in metals, this so-called Atlantis II Deep is also of economic interest,” says co-author Devey. It is quite conceivable that over the course of the earth’s history similar deposits associated with volcanism and salt deposits were created during the opening phase of other oceans. “Thus, our studies help to clarify older research questions. But they also provide starting points for new investigations in all of the oceans,” says Augustin.
Original publication:
Augustin, N., C. W. Devey, F. M. van der Zwan, Peter Feldens, M. Tominaga, R. A. Bantan, T. Kwasnitschka (2014): The rifting to spreading transition in the Red Sea. Earth and Planetary Science Letters, 395, http://dx.doi.org/10.1016/j.epsl.2014.03.047
Note : The above story is based on materials provided by Helmholtz Centre for Ocean Research Kiel (GEOMAR)
This photo shows the approximate location of maximum subsidence in the United States, identified by research efforts of Dr. Joseph F. Poland (pictured). The site is in the San Joaquin Valley southwest of Mendota, Calif. Signs on the pole show approximate altitude of land surface in 1925, 1955, and 1977. Scientists have now found that the groundwater depletion has contributed to rapid uplift of the Sierra Nevada mountains and the California Coast Range as well as affected seismic activity on the San Andreas Fault. Credit: Photo Courtesy USGS.
RENO, Nev. – Like a detective story with twists and turns in the plot, scientists at the University of Nevada, Reno are unfolding a story about the rapid uplift of the famous 400-mile long Sierra Nevada mountain range of California and Nevada.
The newest chapter of the research is being published today in the scientific journal Nature, showing that draining of the aquifer for agricultural irrigation in California’s Central Valley results in upward flexing of the earth’s surface and the surrounding mountains due to the loss of mass within the valley. The groundwater subsidence was found to also correlate with seismic activity on the San Andreas Fault.
University of Nevada, Reno Research Professor Geoff Blewitt also told the story in a presentation at the European Geophysical Sciences Union conference in Vienna, Austria on April 28. The annual EGU General Assembly is the largest and most prominent European geosciences event. It attracts over 11,000 scientists from all over the world.
“We first wrote two years ago about the rapid rise of the Sierra, with its 14,000-foot peaks in the south and 10,000-foot peaks at Lake Tahoe, moving as much as 1 to 3 millimeters per year,” said Blewitt, of the Nevada Bureau of Mines and Geology, a division of the College of Science. “The puzzling results of our earlier research cannot be explained easily by geology alone. We’ve now found that a reason for the rapid uplift may be linked to human activity.”
Over the past 150 years, around 40 trillion gallons of groundwater in California’s Central Valley has been lost through pumping, irrigation and evapotranspiration. That’s roughly equal to all the water in Lake Tahoe, the volume of which can cover the entire state of California in 14 inches of water.
“This massive withdrawal of water has relieved pressure on the Earth’s crust, which is now rebounding upwards in response,” Blewitt said. “This is counter-intuitive to most people, even geologists, who tend to only think that water withdrawal causes subsidence, which is only true in the sediments of the valley from which the water is withdrawn. With the weight of the groundwater missing, the hard-rock crust under the valley is actually rising too.”
The rise is quite fast in geologic time, with these mountain ranges rising by a similar amount each year – about the thickness of a dime – with a cumulative rise over the past 150 years of up to 6 inches, according to the calculations by the team of geophysicists.
Blewitt and colleague Bill Hammond, who run the Nevada Geodetic Laboratory at the University of Nevada, Reno, partnered with the University of Western Washington, the University of California, Berkeley and the University of Ottawa in the research.
“The real importance of this research is that we are demonstrating a potential link between human activity and deformation of the solid Earth, which explains current mountain uplift and the yearly variation in seismicity,” said Colin Amos, assistant professor of geology from Western Washington University and lead author of the Nature article. “These are questions that lots of geologists have been puzzling over, and it’s a real eye opener to think that humans are the ultimate cause.”
The study is based on detailed GPS measurements from California and Nevada between 2007 and 2010. Also working on the study were Pascal Audet of the University of Ottawa and Roland Bürgmann, professor of earth and planetary science at the University of California, Berkeley. The detailed GPS analysis was performed by Hammond and Blewitt with support from the National Science Foundation.
Hammond and Blewitt use data from their Nevada Geodetic Lab and its MAGNET GPS Network, the largest GPS data-processing center in the world, able to process information from about 12,000 stations around the globe continuously, 24/7. The facility measures the shape of the Earth every day using data drawn in from the global network with stations on every continent around the planet, including more than 1,200 stations from the NSF EarthScope Plate Boundary Observatory, as well as stations in space. The space-based radar data comes from the European Space Agency with support from NASA.
“We can sense the long-term flexing of the crust that accompanies trends in climate and related seasonal changes in the Earth’s surface that track yearly precipitation,” Hammond said. “The processing facility at the Nevada Geodetic Laboratory makes it possible to interpret trends in over 500 locations in southern California, needed to measure the centimeter-scale changes these loads produce. It makes it possible for scientists to connect climatic changes to subsidence patterns and the rate of earthquake occurrence.”
“The data is like a gold mine, we keep digging for new discoveries,” he said. “Scientists around the world use it extensively for research such as modeling earthquakes and volcanoes.”
Note : The above story is based on materials provided by University of Nevada, Reno
