September 2019

Crinoids: The Fossils That Inspired 'Alien'

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<tr><td class="tr-caption" style="text-align: center;"><i>Agaricocrinus americanus</i>, crinoïde, carbonifère, Provenance: Indiana.</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">Crinoids  are commonly known as sea lilies due to their "flower-like" appearance , though they are animals, not plants.</span><br />
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Crinoids are part of a large group of marine invertebrate animals called echinoderms. Other echinoderms are starfish, brittle stars, sand dollars, sea urchins, and sea cucumbers. All living echinoderms have what is called pentameral symmetry, which means their bodies are organized in patterns of five; for example, the five arms of the common starfish. Crinoids may have as few as five arms, but usually they have arms in multiples of five.<br />
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Crinoids derived in the Cambrian Period from pelmatozoan ancestors.<br />
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All echinoderms also have calcite plates (ossicles) embedded in their skin, which form their skeleton. That is why living starfish feel scratchy when you touch them. The skeletons of fossil crinoids are very representative of what the animals looked like a-live because only the outer skin layer is missing. <br />
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<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;"> The skeleton is usually divided into four basic parts:</span></h4>
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<li><b>Holdfast</b>, a disc-like sucker, which anchors the crinoid to the ocean bottom;</li>
<li><b>Stem</b>, filled with muscles, which raises the calyx above the substrate;</li>
<li><b>Calyx</b>, a cup-shaped central structure , which contains the internal organs; and</li>
<li><b>Arms </b>- from five to as many as 200 feeding arms (in multiples of five).</li>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-jzQJwxOkBHo/XZIp0PiWecI/AAAAAAAARd0/D8wOeNu-VLg_SW6IYTnMsvZejTz5EAdcQCLcBGAsYHQ/s1600/Fossils%2Bof%2BSeirocrinus%2Bsubsingularis%2Bfrom%2Bthe%2BJurassic%2BHolzmaden%2BBlack%2BShale%2BFormation%252C%2BGermany.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Crinoids: The Fossils That Inspired 'Alien'" border="0" data-original-height="1024" data-original-width="768" height="400" src="https://1.bp.blogspot.com/-jzQJwxOkBHo/XZIp0PiWecI/AAAAAAAARd0/D8wOeNu-VLg_SW6IYTnMsvZejTz5EAdcQCLcBGAsYHQ/s400/Fossils%2Bof%2BSeirocrinus%2Bsubsingularis%2Bfrom%2Bthe%2BJurassic%2BHolzmaden%2BBlack%2BShale%2BFormation%252C%2BGermany.jpg" title="" width="300" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fossils of <i>Seirocrinus subsingularis</i> from the Jurassic Holzmaden Black Shale Formation, Germany</td></tr>
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The largest Sea Lily has a large calyx which with its arms gives it a diametrer of 1.5 metres. The largest Feather star has an armspan of 35 cm. The smallest Crinoids are around 3 cm in diameter.<br />
Most species are nocturnal filter feeders consuming plankton and decaying organic matter.<br />
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To feed they spread their feeding arms to sieve the passing sea water for microscopic organisms and detritus. Mucus, on the tube feet traps their food which is passed down the arms into the mouth by beating cilia. They have a U-shaped digestive system with the anus next to the mouth.<br />
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Not much is known about what eats them although fish and other Echinoderms (especially Sea urchins) are known predators. Sea lilies have been observed crawling away from Sea urchins.<br />
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Crinoids are either male or female with fertilization taking place in the water. The eggs hatch to form free-swimming larva which do not feed and settle on the bottom after a few days after which they metamorphise into an adult in 8 to 12 months. Some hatch as miniature adults, while some females even hold the eggs in their arms until they hatch.<br />
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The first true Crinoids appeared during the Lower Ordovician.  Following the global mass extinction at the Silurian boundary, they and  underwent several major radiations at the early Devonian, Missisippian  (peak) and Pennsylvanian. They almost became extinct at the end of  Paleozoic Era in the Permian, but recovered to flourish again during the  Mesozoic, in the Triassic and Jurassic (Lias, Dogger, Malm). Decreasing  numbers in the Cretaceaous, fossil record of crinoidsis rare in the  Tertiary. More than 6,000 fossil species, belonging to more than 800  genera, have been described. <br />
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Today, approximately 600  living species are known; most free-living feather stars or comatulids  living in the shallow seas.  About 80 species of stalked sea lilies are  restricted to the deeper water of today`s ocean. <br />
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Crinoids were very successful in the Paleozoic. They were most  abundant and diverse in the Mississippian when several continents were  covered with shallow seas. Thick layers of limestone stratigraphy  throughout North America and Europe are full of crinoid stems.<br />
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<br /><span style="font-family: Georgia, "Times New Roman", serif;">See also:  <br /><a href="https://www.geologyin.com/2018/01/the-largest-insect-ever-existed-was.html" target="_blank">The Largest Insect Ever Existed Was a Giant 'Dragonfly'</a><br /><a href="https://www.geologyin.com/2019/05/the-largest-ammonite-ever-found.html" target="_blank">The Largest Ammonite Ever Found?</a></span></div>

Crinoids: The Fossils That Inspired 'Alien'

Agaricocrinus americanus , crinoïde, carbonifère, Provenance: Indiana. Crinoids are commonly known as sea lilies due to their "f...

What Percent of Earth is Water?

earth, Geology, Researches 8:13 PM

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<tr><td class="tr-caption" style="text-align: center;">Illustration showing all of Earth’s water, liquid fresh water, and water in lakes and rivers. Credit: Howard Perlman, USGS/illustraion by Jack Cook, WHOI</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">The Earth is often compared to a majestic blue marble, especially by those privileged few who have gazed upon it from orbit. This is due to the prevalence of water on the planet's surface. While water itself is not blue, water gives off blue light upon reflection.</span><br />
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For those of us confined to living on the surface, the fact that our world is mostly covered in water is a well known fact. But how much of our planet is made up of water, exactly? Like most facts pertaining to our world, the answer is a little more complicated than you might think, and takes into account a number of different qualifications.<br />
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In simplest terms, water makes up about 71% of the Earth's surface, while the other 29% consists of continents and islands.<br />
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To break the numbers down, 96.5% of all the Earth's water is contained within the oceans as salt water, while the remaining 3.5% is freshwater lakes and frozen water locked up in glaciers and the polar ice caps. Of that fresh water, almost all of it takes the form of ice: 69% of it, to be exact. If you could melt all that ice, and the Earth's surface was perfectly smooth, the sea levels would rise to an altitude of 2.7 km.<br />
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Aside from the water that exists in ice form, there is also the staggering amount of water that exists beneath the Earth's surface. If you were to gather all the Earth's fresh water together as a single mass (as shown in the image above) it is estimated that it would measure some 1,386 million cubic kilometers (km3) in volume.Meanwhile, the amount of water that exists as groundwater, rivers, lakes, and streams would constitute just over 10.6 million km3, which works out to a little over 0.7%. Seen in this context, the limited and precious nature of freshwater becomes truly clear.<br />
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But how much of Earth is water—how much water contributes to the actual mass of the planet? This includes not just the surface of the Earth, but inside as well. Scientists calculate that the total mass of the oceans on Earth is 1.35 x 1018 metric tonnes, which is 1/4400 the total mass of the Earth. In other words, while the oceans cover 71% of the Earth's surface, they only account for 0.02% of our planet's total mass.<br />
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The origin of water on the Earth's surface, as well as the fact that it has more water than any other rocky planet in the Solar System, are two of long-standing mysteries concerning our planet.<br />
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Not that long ago, it was believed that our planet formed dry some 4.6 billion years ago, with high-energy impacts creating a molten surface on the infant Earth. According to this theory, water was brought to the world's oceans thanks to icy comets, trans-Neptunian objects or water-rich meteoroids (protoplanets) from the outer reaches of the main asteroid belt colliding with the Earth.<br />
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However, more recent research conducted by the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, Massachusetts, has pushed the date of these origins back further. According to this new study, the world's oceans also date back 4.6 billion years, when all the worlds of the inner Solar System were still forming.<br />
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This conclusion was reached by examining meteorites thought to have formed at different times in the history of the Solar System. Carbonaceous chondrite, the oldest meteorites that have been dated to the very earliest days of the Solar System, were found to have the same chemistry as those originating from protoplanets like Vesta. This includes a significance presence of water.<br />
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These meteorites are dated to the same epoch in which water was believed to have formed on Earth – some 11 million years after the formation of the Solar System. In short, it now appears that meteorites were depositing water on Earth in its earliest days.<br />
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While not ruling out the possibility that some of the water that covers 71 percent of Earth today may have arrived later, these findings suggest that there was enough already here for life to have begun earlier than thought.<br />
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<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.universetoday.com/65588/what-percent-of-earth-is-water/" rel="nofollow" target="_blank">materials </a>provided by <a href="http://www.universetoday.com/" rel="nofollow" target="_blank">Universe Today</a>.</span></i></u></div>

What Percent of Earth is Water?

Illustration showing all of Earth’s water, liquid fresh water, and water in lakes and rivers. Credit: Howard Perlman, USGS/illustraion by...

Kimberlites: Enigmatic Origin of Diamond-bearing Rocks Revealed

Diamonds, Geochemistry 6:58 PM

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<tr><td class="tr-caption" style="text-align: center;">Tiny inclusions in diamonds, such as this garnet, are evidence that they formed deep in the mantle. Credit: Anetta Banas/University of Alberta</td></tr>
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Our planet formed around 4.54 billion years ago but few hints of this ancient world remain—just a small outcrop of rocks in northwestern Canada dating back 4.03 billion years and tiny crystals of the mineral zircon from western Australia that are about 4.3 billion years old.<br />
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The vast majority of the thin crust that we live on is considerably younger; this lack of preserved older material is a consequence of our dynamic planet.<br />
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The constant jostling of tectonic plates forms and destroys rocks, while the action of the hydrological cycle—rain, rivers, glaciers, oceans—tends to erode and redistribute their constituents.<br />
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For many decades, however, scientists have hypothesized that there are areas deep in the Earth's interior that contain material untouched since the planet was formed.<br />
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These domains of primordial material are leftovers from the ancient event that saw the separation of our planet's core from the silicate component which makes up most of the Earth's crust and mantle.<br />
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Now, new University of Melbourne research is shedding some light on this puzzle using kimberlites—an igneous rock.<br />
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These unusual magmas are the primary source of one of our most treasured commodities—diamonds. They are the only volcanic deposits we know to have come from Earth's deep mantle and they provide a fascinating glimpse into our planet's formation.<br />
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Despite our best efforts, hypotheses about what lies deep in the Earth's interior have remained largely untested.<br />
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<tr><td class="tr-caption" style="text-align: center;">Subduction forced the younger oceanic crust down beneath the supercontinent Pangaea millions of years ago. <br />
Credit: University of Melbourne</td></tr>
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We can create images of our planet's interior using geophysical techniques involving seismic wave transmission, but it is a much harder task to determine the composition of the deep Earth.<br />
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Samples are rarely presented to us for analysis, and we do not have the technology to drill into the Earth's mantle to find this material at its source.<br />
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The deepest hole ever drilled, the Kola Superdeep Borehole in northwest Russia, reaches just over 12 kilometers in depth.<br />
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Although that may sound deep, it's barely one third of the way through the crust in that region. In fact, we would need to dig more than 500 kilometers further into the underlying mantle to have any chance of finding primordial material.<br />
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Many of our ideas about the composition of the Earth's interior actually come from meteorites.<br />
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We believe they derive from catastrophic collisions that released material from deep within early solar system planets that were formed in a similar way to the Earth.<br />
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However, there are rare eruptive events that bring to the surface material from deep in the Earth, such as kimberlites.<br />
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Kimberlite eruptions have never been witnessed, because most kimberlites were formed millions to billions of years ago.<br />
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But we know from their textures and volatile-rich nature that these eruptions must have been extremely violent, traveling through the Earth's mantle at extreme speed and sampling their surroundings as they went.<br />
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A small percentage of diamonds carry tiny inclusions of other minerals which are only stable at great pressures, providing clear evidence of their formation happening at depths of up to 800 kilometers.<br />
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In our study with University of Melbourne researchers Professor David Phillips and Drs Andrea Giuliani and Roland Maas, Professor Graham Pearson from the University of Alberta, and Dr. Geoff Nowell from Durham University, we measured the composition of kimberlites that erupted over a 2.5 billion year period of Earth history; collecting data and samples from thirteen kimberlite fields globally, spanning every continent except Antarctica.<br />
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Using sensitive radioisotope tracers, we can map the evolution of their mantle sources through time.<br />
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Our results show that, prior to around 200 million years ago, all kimberlites that erupted on Earth were likely sourced from a single primordial reservoir, formed soon after Earth's core formed.<br />
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Then, around 200 million years ago, this reservoir appears to have been disrupted.<br />
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This was possibly due to a vast subduction zone established along the margins of the supercontinent Pangaea—the single continent that predated the seven continents that we now have.<br />
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Here, collision between tectonic plates forced the younger oceanic crust down beneath the supercontinent and back into the Earth's deeper mantle. This material may have resulted in the contamination of the primordial reservoir.<br />
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These observations provide our best evidence yet for the existence of an early primordial reservoir within the Earth's mantle—a subject of intense speculation for the last four decades.<br />
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And this major event around 200 million years ago may well have represented a significant turning point in the Earth's geochemical evolution.<br />
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<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.nature.com/articles/d41586-019-02808-w" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.unimelb.edu.au/" rel="nofollow" target="_blank">University of Melbourne</a>.</span></i></u></div>

Kimberlites: Enigmatic Origin of Diamond-bearing Rocks Revealed

Tiny inclusions in diamonds, such as this garnet, are evidence that they formed deep in the mantle. Credit: Anetta Banas/University of Al...

New Evidence of the Sahara's Age

Desert, earth, Researches 8:03 PM

New Evidence of the Sahara's Age

Sahara Desert The Sahara Desert is vast, generously dusty, and surprisingly shy about its age. New research looking into what appears ...

Geochemists Measure New Composition of Earth's Mantle

earth, Geochemistry 7:37 PM

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<tr><td class="tr-caption" style="text-align: center;"><span aria-live="polite" class="fbPhotosPhotoCaption" data-ft="{"tn":"K"}" id="fbPhotoSnowliftCaption" tabindex="0"><span class="hasCaption">Peridot crystals. Photos: right: pegmatite, left: Federico Barlocher</span></span></td></tr>
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What is the chemical composition of the Earth's interior? Because it is impossible to drill more than about ten kilometres deep into the Earth, volcanic rocks formed by melting Earth's deep interior often provide such information. Geochemists at the Universities of Münster (Germany) and Amsterdam (Netherlands) have investigated the volcanic rocks that build up the Portuguese island group of the Azores. </div>
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Their goal: gather new information about the compositional evolution of the Earth's mantle, which is the layer roughly between 30 and 2,900 kilometres deep inside the Earth. Using sophisticated analytical techniques, they discovered that the composition of the mantle below the Azores is different than previously thought -suggesting that large parts of it contain surprisingly few so-called incompatible elements. These are chemical elements which, as a result of the constant melting of the Earth's mantle, accumulate in the Earth's crust, which is Earth's outermost solid layer.<br />
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The researchers conclude that, over Earth's history, a larger amount of Earth's mantle has melted -- and ultimately formed the Earth's crust -- than previously thought. "To sustain the material budget between Earth's mantle and crust, mass fluxes between the surface and Earth's interior must have operated at a higher rate," says Münster University's Prof. Andreas Stracke, who is heading the study.<br />
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As the material below the Azores rises from very deep within Earth's mantle -- and is unexpectedly similar to most of its upper part -- the composition of Earth's entire mantle may differ from current thinking. "Our results have opened up a new perspective," says Andreas Stracke, "because we will now have to reassess the composition of the largest part of the Earth -- after all, Earth's mantle accounts for over 80 percent of Earth's volume." The study has been published in the journal Nature Geoscience.</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Background and method</span></h4>
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In their study, the geochemists examined the mineral olivine and its melt inclusions, i.e. magma encapsulated during the crystallisation of olivine before the lavas erupted. The researchers isolated these melt inclusions, just a few micrometers in size, dissolved them chemically and separated certain chemical elements. These elements are altered by radioactive decay during their lifetime and ascent from Earth's interior -- travelling over thousands of kilometres for hundreds or even thousands of millions of years.<br />
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The researchers analysed the isotopic composition of the melts with highly sensitive mass spectrometers. Such methods allow measurement of the relative abundance of different atoms in an element -- so-called isotopes. "Owing to the high efficiency of our measurements, we were able to analyse the isotopic composition of one billionth of a gram of the element," says co-author Dr. Felix Genske from the University of Münster's Institute of Mineralogy, who carried out most of the analytical work. In this way, the researchers indirectly obtained information on the composition of the material in the Earth's mantle: the isotope analyses showed that it contains far fewer rare Earth elements such as samarium and neodymium, but also of chemically similar elements such as thorium and uranium.<br />
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"On the basis of similar geochemical data in volcanic rocks from different regions, e.g. Hawaii, other parts of the Earth's mantle may also contain a higher proportion of material that is strongly depleted in incompatible elements," says Andreas Stracke. The researchers presume that this global deficit may be compensated by a higher rate of recycling Earth's incompatible element-rich crust back into Earth's mantle. With their continuing studies the researchers want to confirm their working hypothesis by investigating samples from other volcanic islands across the globe.</div>
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.uni-muenster.de/news/view.php?cmdid=10521" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.uni-muenster.de/" rel="nofollow" target="_blank">University of Münster</a>.</span></i></u></div>

Geochemists Measure New Composition of Earth's Mantle

Peridot crystals. Photos: right: pegmatite, left: Federico Barlocher What is the chemical composition of the Earth's interior? B...

Lapis Lazuli: Composition and Color

Geochemistry, Rocks 7:03 PM

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<tr><td class="tr-caption" style="text-align: center;">Polished Lapis lazuli. Photo:  New Moon Beginnings</td></tr>
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Lapis lazuli is a blue metamorphic rock that has been used by people as a gemstone, sculpting material, and ornamental material for thousands of years.<br />
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The most important mineral component of lapis lazuli is lazurite (25% to 40%), a feldspathoid silicate mineral with the formula (Na,Ca)<sub>8</sub>(AlSiO<sub>4</sub>)<sub>6</sub>(S,SO<sub>4</sub>,Cl)<sub>1-2</sub>. Most lapis lazuli also contains calcite (white), sodalite (blue), and pyrite (metallic yellow). Some samples of lapis lazuli contain augite; diopside; enstatite; mica; hauynite; hornblende, nosean, and sulfur-rich löllingite geyerite.<br />
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Lapis lazuli usually occurs in crystalline marble as a result of contact metamorphism.<br />
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Lazurite is a tectosilicate mineral with sulfate, sulfur and chloride with formula: (Na,Ca)<sub>8</sub>[(S,Cl,SO<sub>4</sub>,OH)<sub>2</sub>|(Al<sub>6</sub>Si<sub>6</sub>O<sub>24</sub>)]. It is a feldspathoid and a member of the sodalite group. Lazurite crystallizes in the isometric system although well formed crystals are rare. It is usually massive and forms the bulk of the gemstone lapis lazuli.<br />
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The intense blue color is due to the presence of the trisulfur radical anion (S<sub>3</sub><sup>-</sup>) in the crystal.<br />
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Lapis takes an excellent polish and can be made into jewelry, carvings, boxes, mosaics, ornaments, small statues, and vases. During the Renaissance, lapis was ground and processed to make the pigment ultramarine for use in frescoes and oil painting. Its usage as a pigment in oil paint largely ended in the early 19th century when a chemically identical synthetic variety became available.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-V_9kpNMV2xM/XYTucW6IXDI/AAAAAAAARcE/cAeK9BTdG0cu5koYtbOL5S6RuDkrx8FgQCLcBGAsYHQ/s1600/rough%2Blapis%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="810" data-original-width="1080" height="300" src="https://1.bp.blogspot.com/-V_9kpNMV2xM/XYTucW6IXDI/AAAAAAAARcE/cAeK9BTdG0cu5koYtbOL5S6RuDkrx8FgQCLcBGAsYHQ/s400/rough%2Blapis%2B%25281%2529.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Rough lapis. Photo: Arsaa Gems And Minerals</td></tr>
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High-quality lapis lazuli has been used as a mineral pigment for over 1,000 years. Bright blue pieces of lapis are trimmed of impurities and ground to a fine powder; the powder can then be mixed with oil or another vehicle for use as a paint.<br />
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<span style="font-family: "georgia" , "times new roman" , serif;">Where is Lapis Lazuli Found?</span></h4>
Lapis lazuli was discovered around 6,000 years ago in the West Hindu-Kush Mountains of present-day Afghanistan. Today, Afghanistan continues to be the leading producer of the gem. Other countries involved in production include Angola, Argentina, Canada, Chile, India, Italy, Myanmar, Pakistan, the United States, and Russia. <br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-6VosfbQg3bE/XYEQ-TlEkQI/AAAAAAAARbI/BWkrd_bTAuMQ8juosizPjabxuR8KfmP4wCLcBGAsYHQ/s1600/Ultramarinepigment%2B%25282%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="480" data-original-width="640" height="300" src="https://1.bp.blogspot.com/-6VosfbQg3bE/XYEQ-TlEkQI/AAAAAAAARbI/BWkrd_bTAuMQ8juosizPjabxuR8KfmP4wCLcBGAsYHQ/s400/Ultramarinepigment%2B%25282%2529.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"> Ultramarine Pigment</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">Ultramarine </span></h4>
Ultramarine is a deep blue color pigment which was originally made by grinding lapis lazuli into a powder. The name comes from the Latin ultramarinus, literally "beyond the sea", because the pigment was imported into Europe from mines in Afghanistan.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">See also:</span></b><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2018/10/chrysanthemum-stone-natural-flower-stone.html" target="_blank">Chrysanthemum Stone: Natural Flower Stone </a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2019/06/what-is-hopper-crystal.html" target="_blank">What is Hopper Crystal?</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2019/06/what-is-fire-agate.html" target="_blank">What is Fire Agate?</a></span></div>

Lapis Lazuli: Composition and Color

Polished Lapis lazuli. Photo: New Moon Beginnings Lapis lazuli is a blue metamorphic rock that has been used by people as a gemstone...

Gigantic Masses in Earth’s Mantle Untouched for More Than 4 Billion Years

earth, Geology 8:44 PM

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<tr><td class="tr-caption" style="text-align: center;">This image shows the divisions between Earth’s layers. The ancient, continent-sized rock regions encircle the liquid outer core.</td></tr>
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Ancient, distinct, continent-sized regions of rocks, isolated since before the collision that created the Moon 4.5 billion years ago, exist hundreds of miles below the Earth's crust, offering a window into the building blocks of our planet, according to new research.<br />
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The new study in the AGU journal Geochemistry, Geophysics, Geosystems used models to trace the location and origin of volcanic rock samples found throughout the world back to two solid continents in the deep mantle. The new research suggests the specific giant rock regions have existed for 4.5 billion years, since Earth's beginning.<br />
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Previously, scientists theorized that separated continents in the deep mantle came from subducted oceanic plates. But the new study indicates these distinct regions may have been formed from an ancient magma ocean that solidified during the beginning of Earth's formation and may have survived the massive Moon-creating impact.<br />
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Determining the masses' origin reveals more details about their evolution and composition, as well as clues about primordial Earth's history in the early Solar System, according to the study's authors.<br />
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It's amazing that these regions have survived most of Earth's volcanic history relatively untouched, said Curtis Williams, a geologist at the University of California, Davis, in Davis, California and lead author of the study.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">Looking inward</span></h4>
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The mantle is a layer of rock, stretching 2,900 kilometers (1,802 miles) down inside the Earth. Earth's molten, liquid, metallic core lies beneath the mantle. The core-mantle boundary is where the solid mantle meets the metallic liquid core.<br />
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Scientists knew from past seismic imaging studies that two individual rock bodies existed near the core-mantle boundary. One solid rock body is under Africa and the other is under the Pacific Ocean.<br />
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Seismic waves, the vibrations produced by earthquakes, move differently through these masses than the rest of the mantle, suggesting they have distinct physical properties from the surrounding mantle. But geologists couldn't determine whether seismic waves moved differently through the core-mantle continents because of differences in their temperature, mineral composition or density, or some combination of these properties. That meant they could only hypothesize about the separate rocky masses' origin and history.<br />
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"We had all of these geochemical measurements from Earth's surface, but we didn't know how to relate these geochemical measurements to regions of Earth's interior. We had all of these geophysical images of the Earth's interior, but we didn't know how to relate that to the geochemistry at Earth's surface," Williams said.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">Primitive material and plumes</span></h4>
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Williams and his colleagues wanted to determine the distinct masses' origin and evolution to learn more about Earth's composition and past. To do this, they needed to be able to identify samples at Earth's surface with higher concentrations of primitive material and then trace those samples back to their origins.<br />
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Scientists often take rock samples from volcanic regions like Hawaii and Iceland, where deep mantle plumes, or columns of extremely hot rock, rise from the areas near the core, melt in the shallow mantle and emerge far from tectonic fault lines. These samples are made of igneous rock created from cooling lava. The study's authors used an existing database of samples and also collected new samples from volcanically active areas like the Balleny Islands in Antarctica.<br />
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Geologists can measure specific isotopes in igneous rocks to learn more about the origin and evolution of the Earth. Some isotopes, like Helium-3, are primordial, meaning they were created during the Big Bang. Rocks closer to Earth's crust have less of the isotope than rocks deeper underground that were never exposed to air. Samples with more Helium-3 are thought to come from more primitive rocks in the mantle.<br />
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The researchers found some of the samples they studied had more Helium-3, indicating they may have come from primitive rocks deep in the Earth's mantle.<br />
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The researchers then used a new model to trace how these primitive samples could have gotten to the Earth's surface from the mantle. Geological models assume plumes rise vertically from deep within the mantle to the Earth's surface. But plumes can move off course, deflected, due to various reasons. The new model took into account this plume deflection, allowing the study's authors to trace the samples back to the two giant masses near the core-mantle boundary.<br />
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The combination of the isotope information and the new model allowed the researchers to determine the composition of the two giant masses and theorize how they may have formed.<br />
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Understanding the composition of specific rock masses near the core-mantle boundary helps geologists conceptualize ancient Earth-shaping processes that led to the modern-day mantle, according to the study's authors.<br />
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"It's a more robust framework to try and answer these questions in terms of not making these assumptions of vertically rising material but rather to take into account how much deflection these plumes have seen," Williams said.</div>
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://blogs.agu.org/geospace/2019/09/18/new-study-suggests-gigantic-masses-in-earths-mantle-untouched-for-more-than-4-billion-years/" rel="nofollow" target="_blank">materials </a>provided by  American Geophysical Union.</span></i></u></div>
</div>

Gigantic Masses in Earth’s Mantle Untouched for More Than 4 Billion Years

This image shows the divisions between Earth’s layers. The ancient, continent-sized rock regions encircle the liquid outer core. Anc...

Scientist Discovers Unusual New Mineral Inside a Diamond

Diamonds, Geochemistry, Mineralogy 8:09 PM

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A Ph.D. student at the University of Alberta has discovered a new and curious mineral inside a diamond unearthed from a mine in South Africa.<br />
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The mineral—named goldschmidtite in honor of Victor Moritz Goldschmidt, the founder of modern geochemistry—has an unusual chemical signature for a mineral from Earth's mantle, explained Nicole Meyer, a graduate student in the Diamond Exploration Research and Training School.<br />
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"Goldschmidtite has high concentrations of niobium, potassium and the rare earth elements lanthanum and cerium, whereas the rest of the mantle is dominated by other elements, such as magnesium and iron," said Meyer.<br />
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"For potassium and niobium to constitute a major proportion of this mineral, it must have formed under exceptional processes that concentrated these unusual elements."<br />
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The researchers estimate the diamond containing the goldschmidtite formed about 170 kilometers beneath Earth's surface, at temperatures reaching nearly 1,200 C.<br />
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Because it is so difficult to drill down through Earth's crust to reach the mantle, scientists rely on tiny mineral inclusions within diamonds to learn more about Earth's chemistry deep beneath the surface.<br />
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"(The discovery) gives us a snapshot of fluid processes that affect the deep roots of continents during diamond formation," said Meyer's co-supervisor, Graham Pearson, who added there have been several attempts to name new minerals after Goldschmidt, but previous ones have been discredited. "This one is here to stay."<br />
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"The work that goes into finding a new mineral is not done by one person," said Meyer, who is also studying under the supervision of Thomas Stachel, professor and Canada Research Chair in Diamonds. "It has been an interdisciplinary collaboration with mineralogist Andrew Locock, crystallographers from Northwestern University, my advisers Thomas and Graham, and technicians."<br />
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The study, "Goldschmidtite, (K,REE,Sr)(Nb,Cr)O<sub>3</sub>: a New Perovskite Supergroup Mineral Found in Diamond from Koffiefontein, South Africa," was published in American Mineralogist.<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="http://dx.doi.org/10.2138/am-2019-6937" rel="nofollow" target="_blank">materials </a>provided by  <a href="https://www.ualberta.ca/" rel="nofollow" target="_blank">University of Alberta</a>.</span></i></u></div>

Scientist Discovers Unusual New Mineral Inside a Diamond

A Ph.D. student at the University of Alberta has discovered a new and curious mineral inside a diamond unearthed from a mine in South A...

What Happens When Magnetic North and True North Align?

earth, Earth's magnetic field, Researches 7:29 PM

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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-eC4e0lbpR3Q/XYJbLMBaN_I/AAAAAAAARbg/fj1m6Hi3XPo1pqfuFsBIWDjl74hgrorvACLcBGAsYHQ/s1600/What%2BHappens%2BWhen%2BMagnetic%2BNorth%2Band%2BTrue%2BNorth%2BAlign%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="What Happens When Magnetic North and True North Align?" border="0" data-original-height="1031" data-original-width="1200" height="548" src="https://1.bp.blogspot.com/-eC4e0lbpR3Q/XYJbLMBaN_I/AAAAAAAARbg/fj1m6Hi3XPo1pqfuFsBIWDjl74hgrorvACLcBGAsYHQ/s640/What%2BHappens%2BWhen%2BMagnetic%2BNorth%2Band%2BTrue%2BNorth%2BAlign%2B%25281%2529.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The lines of the Earth’s magnetic field come vertically out of the Earth at the south magnetic pole and go vertically down into the Earth at the north magnetic pole. Credit: Nasky/Shutterstock</td></tr>
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At some point in recent weeks, a once-in-a-lifetime event happened for people at Greenwich in the United Kingdom.<br />
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Magnetic compasses at the historic London area, known as the home of the Prime Meridian, were said to have pointed directly at the north geographic pole for the first time in 360 years.<br />
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This means that, for someone at Greenwich, magnetic north (the direction in which a compass needle points) would have been in exact alignment with geographic north.<br />
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Geographic north (also called "true north") is the direction towards the fixed point we call the North Pole.<br />
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Magnetic north is the direction towards the north magnetic pole, which is a wandering point where the Earth's magnetic field goes vertically down into the planet.<br />
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The north magnetic pole is currently about 400km south of the north geographic pole, but can move to about 1,000km away.</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">How do the norths align?</span></h4>
<div style="text-align: left;">
Magnetic north and geographic north align when the so-called "angle of declination," the difference between the two norths at a particular location, is 0°.<br />
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Declination is the angle in the horizontal plane between magnetic north and geographic north. It changes with time and geographic location.<br />
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On a map of the Earth, lines along which there is zero declination are called agonic lines. Agonic lines follow variable paths depending on time variation in the Earth's magnetic field.<br />
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Currently, zero declination is occurring in some parts of Western Australia, and will likely move westward in coming years.<br />
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That said, it's hard to predict exactly when an area will have zero declination. This is because the rate of change is slow and current models of the Earth's magnetic field only cover a few years, and are updated at roughly five-year intervals.<br />
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At some locations, alignment between magnetic north and geographic north is very unlikely at any time, based on predictions.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">The ever-changing magnetic poles</span></h4>
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Most compasses point towards Earth's north magnetic pole, which is usually in a different place to the north geographic pole. The location of the magnetic poles is constantly changing.<br />
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Earth's magnetic poles exist because of its magnetic field, which is produced by electric currents in the liquid part of its core. This magnetic field is defined by intensity and two angles, inclination and declination.<br />
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The relationship between geographic location and declination is something people using magnetic compasses have to consider. Declination is the reason a compass reading for north in one location is different to a reading for north in another, especially if there is considerable distance between both locations.<br />
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Bush walkers have to be mindful of declination. In Perth, declination is currently close to 0° but in eastern Australia it can be up to 12°. This difference can be significant. If a bush walker following a magnetic compass disregards the local value of declination, they may walk in the wrong direction.<br />
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The polarity of Earth's magnetic poles has also changed over time and has undergone pole reversals. This was significant as we learnt more about plate tectonics in the 1960s, because it linked the idea of seafloor spreading from mid-ocean ridges to magnetic pole reversals.</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Geographic north</span></h4>
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Geographic north, perhaps the more straightforward of the two, is the direction that points straight at the North Pole from any location on Earth.<br />
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When flying an aircraft from A to B, we use directions based on geographic north. This is because we have accurate geographic locations for places and need to follow precise routes between them, usually trying to minimise fuel use by taking the shortest route. All GPS navigation uses geographic location.<br />
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Geographic coordinates, latitude and longitude, are defined relative to Earth's spheroidal shape. The geographic poles are at latitudes of 90°N (North Pole) and 90°S (South Pole), whereas the Equator is at 0°.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">An alignment at Greenwich</span></h4>
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For hundreds of years, declination at Greenwich was negative, meaning compass needles were pointing west of true north.<br />
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At the time of writing this article I used an online calculator to discover that, at the Greenwich Observatory, the Earth's magnetic field currently has a declination just above zero, about +0.011°.<br />
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The average rate of change in the area is about 0.19° per year, which at Greenwich's latitude represents about 20km per year. This means next year, locations about 20km west of Greenwich will have zero declination.<br />
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It's impossible to say how long compasses at Greenwich will now point east of true north.<br />
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Regardless, an alignment after 360 years at the home of the Prime Meridian is undoubtedly a once-in-a-lifetime occurrence.</div>
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">This article is republished from <a href="https://theconversation.com/explainer-what-happens-when-magnetic-north-and-true-north-align-123265" rel="nofollow" target="_blank">The Conversation</a> under a Creative Commons license.</span></i></u></div>

What Happens When Magnetic North and True North Align?

The lines of the Earth’s magnetic field come vertically out of the Earth at the south magnetic pole and go vertically down into the Earth...

Scientists Uncover 550 Million-Year-Old Fossils of Bug Trails

Earth History, Fossils 8:22 PM

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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-LCvf1Dx891Y/XX5zIyP2nTI/AAAAAAAARaw/ITwmPhVjSYIqn1l9hurVh0YQN4Cp7F2mQCLcBGAsYHQ/s1600/Scientists%2BUncover%2B550%2BMillion-Year-Old%2BFossils%2Bof%2BBug%2BTrails.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="700" data-original-width="1200" height="372" src="https://1.bp.blogspot.com/-LCvf1Dx891Y/XX5zIyP2nTI/AAAAAAAARaw/ITwmPhVjSYIqn1l9hurVh0YQN4Cp7F2mQCLcBGAsYHQ/s640/Scientists%2BUncover%2B550%2BMillion-Year-Old%2BFossils%2Bof%2BBug%2BTrails.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A fossil of Yilingia spiciformis and the track it left as it moved. (Z. Chen et al. / Nature)</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">A 550-million-year-old worm was one of the first animals to move and make decisions, a new study says</span><br />
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In a remarkable evolutionary discovery, a team of scientists co-led by a Virginia Tech geoscientist has discovered what could be among the first trails made by animals on the surface of the Earth roughly a half-billion years ago.<br />
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Shuhai Xiao, a professor of geosciences with the Virginia Tech College of Science, calls the unearthed fossils, including the bodies and trails left by an ancient animal species, the most convincing sign of ancient animal mobility, dating back about 550 million years. Named Yilingia spiciformis - that translates to spiky Yiling bug, Yiling being the Chinese city near the discovery site - the animal was found in multiple layers of rock by Xiao and Zhe Chen, Chuanming Zhou, and Xunlai Yuan from the Chinese Academy of Sciences' Nanjing Institute of Geology and Palaeontology.<br />
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The findings are published in the latest issue of Nature. The trials are from the same rock unit and are roughly the same age as bug-like footprints found by Xiao and his team in a series of digs from 2013 to 2018 in the Yangtze Gorges area of southern China, and date back to the Ediacaran Period, well before the age of dinosaurs or even the Pangea supercontinent. What sets this find apart: The preserved fossil of the animal that made the trail versus the unknowable guesswork where the body has not been preserved.<br />
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"This discovery shows that segmented and mobile animals evolved by 550 million years ago," Xiao said. "Mobility made it possible for animals to make an unmistakable footprint on Earth, both literally and metaphorically. Those are the kind of features you find in a group of animals called bilaterans. This group includes us humans and most animals. Animals and particularly humans are movers and shakers on Earth. Their ability to shape the face of the planet is ultimately tied to the origin of animal motility."<br />
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The animal was a millipede-like creature a quarter-inch to an inch wide and up to 4 inches long that alternately dragged its body across the muddy ocean floor and rested along the way, leaving trails as loing as 23 inches. The animal was an elongated narrow creature, with 50 or so body segments, a left and right side, a back and belly, and a head and a tail.<br />
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The origin of bilaterally symmetric animals - known as bilaterians -- with segmented bodies and directional mobility is a monumental event in early animal evolution, and is estimated to have occurred the Ediacaran Period, between 635 and 539 million years ago. But until this finding by Xiao and his team, there was no convincing fossil evidence to substantiate those estimates. One of the recovered specimens is particularly vital because the animal and the trail it produced just before its death are preserved together.<br />
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Remarkably, the find also marks what may be the first sign of decision making among animals - the trails suggest an effort to move toward or away from something, perhaps under the direction of a sophisticated central nerve system, Xiao said. The mobility of animals led to environmental and ecological impacts on the Earth surface system and ultimately led to the Cambrian substrate and agronomic revolutions, he said.<br />
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"We are the most impactful animal on Earth," added Xiao, also an affiliated member of the Global Change Center at Virginia Tech. "We make a huge footprint, not only from locomotion, but in many other and more impactful activities related to our ability to move. When and how animal locomotion evolved defines an important geological and evolutionary context of anthropogenic impact on the surface of the Earth."<br />
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Rachel Wood, a professor in the School of GeoSciences at University of Edinburgh in Scotland, who was not involved with the study, said, "This is a remarkable finding of highly significant fossils. We now have evidence that segmented animals were present and had gained an ability to move across the sea floor before the Cambrian, and more notably we can tie the actual trace-maker to the trace. Such preservation is unusual and provides considerable insight into a major step in the evolution of animals."<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://vtnews.vt.edu/articles/2019/09/Science-Shuhai_Xiao_half_billion_animal_trail.html" rel="nofollow" target="_blank">materials </a>provided by  <a href="https://vt.edu/" rel="nofollow" target="_blank">Virginia Tech.</a></span></i></u></div>

Scientists Uncover 550 Million-Year-Old Fossils of Bug Trails

A fossil of Yilingia spiciformis and the track it left as it moved. (Z. Chen et al. / Nature) A 550-million-year-old worm was one of ...

There's a Lost Continent Hiding Beneath Europe

Earth History, Researches, Tectonic 7:59 PM

There's a Lost Continent Hiding Beneath Europe

Photo: The Sun Researchers uncovered traces of a lost continent that disappeared under what is today Europe about 120 million years a...

Rocks at Asteroid Impact Site Record First Day of Dinosaur Extinction

dinosaur, extinction 7:34 PM

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<span style="font-family: "georgia" , "times new roman" , serif;">Asteroid as Powerful as 10 Billion World War II Atomic Bombs May Have Wiped Out the Dinosaurs</span><br />
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When the asteroid that wiped out the dinosaurs slammed into the planet, the impact set wildfires, triggered tsunamis and blasted so much sulfur into the atmosphere that it blocked the sun, which caused the global cooling that ultimately doomed the dinos.<br />
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That's the scenario scientists have hypothesized. Now, a new study led by The University of Texas at Austin has confirmed it by finding hard evidence in the hundreds of feet of rocks that filled the impact crater within the first 24 hours after impact.<br />
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The evidence includes bits of charcoal, jumbles of rock brought in by the tsunami's backflow and conspicuously absent sulfur. They are all part of a rock record that offers the most detailed look yet into the aftermath of the catastrophe that ended the Age of Dinosaurs, said Sean Gulick, a research professor at the University of Texas Institute for Geophysics (UTIG) at the Jackson School of Geosciences.<br />
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"It's an expanded record of events that we were able to recover from within ground zero," said Gulick, who led the study and co-led the 2016 International Ocean Discovery Program scientific drilling mission that retrieved the rocks from the impact site offshore of the Yucatan Peninsula. "It tells us about impact processes from an eyewitness location."<br />
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The research was published in the Proceedings of the National Academy of Sciences on Sept. 9 and builds on earlier work co-led and led by the Jackson School that described how the crater formed and how life quickly recovered at the impact site. An international team of more than two dozen scientists contributed to this study.<br />
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Most of the material that filled the crater within hours of impact was produced at the impact site or was swept in by seawater pouring back into the crater from the surrounding Gulf of Mexico. Just one day deposited about 425 feet of material -- a rate that's among the highest ever encountered in the geologic record. This breakneck rate of accumulation means that the rocks record what was happening in the environment within and around the crater in the minutes and hours after impact and give clues about the longer-lasting effects of the impact that wiped out 75% of life on the planet.<br />
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Gulick described it as a short-lived inferno at the regional level, followed by a long period of global cooling.<br />
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"We fried them and then we froze them," Gulick said. "Not all the dinosaurs died that day, but many dinosaurs did."<br />
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Researchers estimate the asteroid hit with the equivalent power of 10 billion atomic bombs of the size used in World War II. The blast ignited trees and plants that were thousands of miles away and triggered a massive tsunami that reached as far inland as Illinois. Inside the crater, researchers found charcoal and a chemical biomarker associated with soil fungi within or just above layers of sand that shows signs of being deposited by resurging waters. This suggests that the charred landscape was pulled into the crater with the receding waters of the tsunami.<br />
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Jay Melosh, a Purdue University professor and expert on impact cratering, said that finding evidence for wildfire helps scientists know that their understanding of the asteroid impact is on the right track.<br />
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"It was a momentous day in the history of life, and this is a very clear documentation of what happened at ground zero," said Melosh, who was not involved with this study.<br />
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However, one of the most important takeaways from the research is what was missing from the core samples. The area surrounding the impact crater is full of sulfur-rich rocks. But there was no sulfur in the core.<br />
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That finding supports a theory that the asteroid impact vaporized the sulfur-bearing minerals present at the impact site and released it into the atmosphere, where it wreaked havoc on the Earth's climate, reflecting sunlight away from the planet and causing global cooling. Researchers estimate that at least 325 billion metric tons would have been released by the impact. To put that in perspective, that's about four orders of magnitude greater than the sulfur that was spewed during the 1883 eruption of Krakatoa -- which cooled the Earth's climate by an average of 2.2 degrees Fahrenheit for five years.<br />
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Although the asteroid impact created mass destruction at the regional level, it was this global climate change that caused a mass extinction, killing off the dinosaurs along with most other life on the planet at the time.<br />
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"The real killer has got to be atmospheric," Gulick said. "The only way you get a global mass extinction like this is an atmospheric effect."<br />
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The research was funded by a number of international and national support organizations, including the National Science Foundation.<br />
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<i><u><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://news.utexas.edu/2019/09/09/rocks-at-asteroid-impact-site-record-first-day-of-dinosaur-extinction/" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.utexas.edu/" rel="nofollow" target="_blank">University of Texas at Austin</a>. </span></u></i><span style="background-color: white; color: #333333; display: inline; float: none; font-family: "helvetica neue" , "helvetica" , "arial" , sans-serif; font-size: 14px; font-style: normal; font-weight: 400; letter-spacing: normal; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><br />
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Rocks at Asteroid Impact Site Record First Day of Dinosaur Extinction

Asteroid as Powerful as 10 Billion World War II Atomic Bombs May Have Wiped Out the Dinosaurs When the asteroid that wiped out the di...

Pyrite: Fool's Gold

Geochemistry, Mineral, Mineralogy 7:12 PM

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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-dsJpnk_6DgA/Xo3iUSw14RI/AAAAAAAASF8/PlBSD2AscP4KsOFf6jqCNati1U2IdefWwCLcBGAsYHQ/s1600/Interesting%2BFacts%2BAbout%2B%2BFool%2527s%2BGold%2B%25282%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Pyrite: Fool's Gold" border="0" data-original-height="800" data-original-width="1200" height="426" src="https://1.bp.blogspot.com/-dsJpnk_6DgA/Xo3iUSw14RI/AAAAAAAASF8/PlBSD2AscP4KsOFf6jqCNati1U2IdefWwCLcBGAsYHQ/s640/Interesting%2BFacts%2BAbout%2B%2BFool%2527s%2BGold%2B%25282%2529.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cubic Crystals of Pyrite Nestled Within a Matrix of Rhodochrosite. From Cassandra Mines,macedonia Dept, Greece<br />Credit: Crystalclassics.co.uk</td></tr>
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Pyrite  is an iron sulfide with the chemical formula FeS<sub>2</sub> (iron(II)  disulfide). Pyrite is considered the most common of the sulfide  minerals.<br />
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Pyrite is sometimes called Fools Gold because of its similarity in color and shape to Gold. In the old mining days, Pyrite was sometimes mistaken for Gold, as they frequently occur together. <br />
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Pyrite occurs in numerous shapes and habits. The smaller crystal aggregates may give off a beautiful glistening effect in light, and the larger crystals may be perfectly formed, including fascinating cubes, penetration twins, and other interesting crystal forms.<br />
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Pyrite has the same chemical formula as the rarer mineral Marcasite, but it crystallizes in a different crystal system, thereby classifying it as a separate mineral species. <br />
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Pyrite is usually found associated with other sulfides or oxides in quartz veins, sedimentary rock, and metamorphic rock, as well as in coal beds and as a replacement mineral in fossils, but has also been identified in the sclerites of scaly-foot gastropods.<br />
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 Despite being nicknamed fool's gold, pyrite is sometimes found in association with small quantities of gold.<br />
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Pyrite is quite easy to distinguish from gold: pyrite is much lighter, but harder than gold and cannot be scratched with a fingernail or pocket knife.<br />
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Pyritization: Organisms may become pyritized when they are in marine sediments saturated with iron sulfides. As organic matter decays it releases sulfide which reacts with dissolved iron in the surrounding waters. Pyrite replaces carbonate shell material due to an undersaturation of carbonate in the surrounding waters. <br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-qF3XeWi0d5E/XXkZ8Y17ylI/AAAAAAAARaE/D4GHZ3EeQfQtlX8_X1-oyOae3r0IBuKMACLcBGAsYHQ/s1600/This%2Bis%2Ban%2Bexcellent%2Bexample%2Bof%2Btwo%2Bintergrown%2Bcubes%2Bof%2Bpyrite.%2Bfrom%2BNavaj%25C3%25BAn%252C%2BLa%2BRioja%252C%2BSpain.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Pyrite: Interesting Facts About  Fool's Gold" border="0" data-original-height="800" data-original-width="640" height="400" src="https://1.bp.blogspot.com/-qF3XeWi0d5E/XXkZ8Y17ylI/AAAAAAAARaE/D4GHZ3EeQfQtlX8_X1-oyOae3r0IBuKMACLcBGAsYHQ/s400/This%2Bis%2Ban%2Bexcellent%2Bexample%2Bof%2Btwo%2Bintergrown%2Bcubes%2Bof%2Bpyrite.%2Bfrom%2BNavaj%25C3%25BAn%252C%2BLa%2BRioja%252C%2BSpain.jpg" title="" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This is an excellent example of two intergrown cubes of pyrite. from Navajún, La Rioja, Spain<br />
Photo Mardani Fine Minerals</td></tr>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-4xu5Bl_AKHY/XXkatY6_ciI/AAAAAAAARaM/wnQnQTZzNnsaTuNkO3gF29eBvllm2jrTQCLcBGAsYHQ/s1600/Large%2BSize%2BNatural%2BPyritized%2BAmmonite%2BFossils%2Bfrom%2BRussia..jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Pyrite: Interesting Facts About  Fool's Gold" border="0" data-original-height="960" data-original-width="960" height="400" src="https://1.bp.blogspot.com/-4xu5Bl_AKHY/XXkatY6_ciI/AAAAAAAARaM/wnQnQTZzNnsaTuNkO3gF29eBvllm2jrTQCLcBGAsYHQ/s400/Large%2BSize%2BNatural%2BPyritized%2BAmmonite%2BFossils%2Bfrom%2BRussia..jpg" title="" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Large Size Natural Pyritized Ammonite Fossils from Russia. <br />
Their Chambers are filled with druzy Pyrite!!<br />
Photo credit: Daniel Virgadaula</td></tr>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-_Ui4v-5-Ehk/XXZ9WY0EiMI/AAAAAAAARZc/qdm79hRodfANUPKirgQswNqZ70BQZjbbgCLcBGAs/s1600/Pyrite%2B%2Bis%2Ban%2Biron%2Bsulfide.jpg" style="margin-left: auto; margin-right: auto;"><img alt="Pyrite: Interesting Facts About  Fool's Gold" border="0" data-original-height="944" data-original-width="1080" height="348" src="https://1.bp.blogspot.com/-_Ui4v-5-Ehk/XXZ9WY0EiMI/AAAAAAAARZc/qdm79hRodfANUPKirgQswNqZ70BQZjbbgCLcBGAs/s400/Pyrite%2B%2Bis%2Ban%2Biron%2Bsulfide.jpg" title="" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pyritized ammonite. From Saratov Russia. Upper Callovian (around 162 million years). <br />
Photo: Leah Luten</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">See Also:</span></b><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2019/07/what-is-crazy-lace-agate.html" target="_blank">What is Crazy Lace Agate?</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2018/10/chrysanthemum-stone-natural-flower-stone.html" target="_blank">Chrysanthemum Stone: Natural Flower Stone</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2018/04/what-is-pseudomorph-mineral.html" target="_blank">What Is Pseudomorph Mineral?</a></span><br />
<br /></div>

Pyrite: Fool's Gold

Cubic Crystals of Pyrite Nestled Within a Matrix of Rhodochrosite. From Cassandra Mines,macedonia Dept, Greece Credit: Crystalclassics.c...

Researchers Unearth 'New' Mass-extinction

Earth History, extinction, Researches 7:41 PM

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<span style="font-family: "georgia" , "times new roman" , serif;">A team of scientists has concluded that earth experienced a previously underestimated severe mass-extinction event, which occurred about 260 million years ago, raising the total of major mass extinctions in the geologic record to six.</span><br />
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"It is crucial that we know the number of severe mass extinctions and their timing in order to investigate their causes," explains Michael Rampino, a professor in New York University's Department of Biology and a co-author of the analysis, which appears in the journal Historical Biology. "Notably, all six major mass extinctions are correlated with devastating environmental upheavals -- specifically, massive flood-basalt eruptions, each covering more than a million square kilometers with thick lava flows."<br />
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Scientists had previously determined that there were five major mass-extinction events, wiping out large numbers of species and defining the ends of geological periods: the end of the Ordovician (443 million years ago), the Late Devonian (372 million years ago), the Permian (252 million years ago), the Triassic (201 million years ago), and the Cretaceous (66 million years ago).<br />
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And, in fact, many researchers have raised concerns about the contemporary, ongoing loss of species diversity -- a development that might be labeled a "seventh extinction" because such a modern mass extinction, scientists have predicted, could end up being as severe as these past events.<br />
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The Historical Biology work, which also included Nanjing University's Shu-zhong Shen, focused on the Guadalupian, or Middle Permian period, which lasted from 272 to about 260 million years ago.<br />
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Here, the researchers observe, the end-Guadalupian extinction event -- which affected life on land and in the seas -- occurred at the same time as the Emeishan flood-basalt eruption that produced the Emeishan Traps, an extensive rock formation, found today in southern China. The eruption's impact was akin to those causing other known severe mass extinctions, Rampino says.<br />
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"Massive eruptions such as this one release large amounts of greenhouse gases, specifically carbon dioxide and methane, that cause severe global warming, with warm, oxygen-poor oceans that are not conducive to marine life," he notes.<br />
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"In terms of both losses in the number of species and overall ecological damage, the end-Guadalupian event now ranks as a major mass extinction, similar to the other five," the authors write.<br />
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<br />
<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.nyu.edu/about/news-publications/news/2019/september/researchers-unearth--new--extinction.html" rel="nofollow" target="_blank">Materials</a> provided by <a href="https://www.nyu.edu/" rel="nofollow" target="_blank">New York University</a>.</span></i></u></div>

Researchers Unearth 'New' Mass-extinction

A team of scientists has concluded that earth experienced a previously underestimated severe mass-extinction event, which occurred abou...

Yellowstone’s Steamboat Geyser Breaks Yearly Eruption Record

Geology, USA, Yellowstone 7:39 PM

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The Steamboat Geyser at Yellowstone National Park just broke a record.<br />
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According to the US Geologic Survey, the world’s tallest active geyser had erupted 34 times as of Tuesday, the largest number ever recorded in a year.<br />
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Last year’s record was 32 eruptions and prior to that, the record was 29 in 1964.<br />
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Steamboat’s larger eruptions tend to last from three to 40 minutes and are followed by powerful jets of steam.<br />
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Although the eruptions might seem alarming to some, experts say it’s not necessarily something to worry about.<br />
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“They’re mostly random and experience phases of alternating eruptive activity,” said Michael Poland, the USGS scientist-in-charge of the Yellowstone Volcano Observatory, according to KXPI.<br />
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“So while fascinating, it’s not unusual, nor cause for concern.”<br />
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Poland said it’s a misconception that geyser eruptions are related to earthquake activity, and that visitors should not fear any deeper changes in the park’s volcanic system.<br />
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<a href="https://twitter.com/hashtag/Yellowstone?src=hash&ref_src=twsrc%5Etfw">#Yellowstone</a> Monthly Update<br />
September 3, 2019, 10:53 AM MDT<a href="https://t.co/mXhpTFYLYk">https://t.co/mXhpTFYLYk</a><br />
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- Steamboat had 3 more water eruptions in August, setting a new calendar-year record<br />
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- 128 located quakes in August, including a swarm near West Thumb<br />
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- no significant caldera deformation <a href="https://t.co/xsQgYVY9jM">pic.twitter.com/xsQgYVY9jM</a></div>
— USGS Volcanoes🌋 (@USGSVolcanoes) <a href="https://twitter.com/USGSVolcanoes/status/1168932448333377538?ref_src=twsrc%5Etfw">September 3, 2019</a></blockquote>
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Yellowstone’s Steamboat Geyser Breaks Yearly Eruption Record

The Steamboat Geyser at Yellowstone National Park just broke a record. According to the US Geologic Survey, the world’s tallest activ...

What Drives Plate Tectonics?

earth, Earth History, Tectonic 7:28 PM

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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-8K6Qqobp7ZQ/XW6TaVUjaZI/AAAAAAAARYE/vNmafYnRhzAkT7JJufOfzWAvLOtGYM_TgCLcBGAs/s1600/What%2BDrives%2BPlate%2BTectonics%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="What Drives Plate Tectonics?" border="0" data-original-height="888" data-original-width="1210" height="468" src="https://1.bp.blogspot.com/-8K6Qqobp7ZQ/XW6TaVUjaZI/AAAAAAAARYE/vNmafYnRhzAkT7JJufOfzWAvLOtGYM_TgCLcBGAs/s640/What%2BDrives%2BPlate%2BTectonics%2B%25281%2529.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Global paleomagnetic plate reconstructions a. 270 Ma, b. 180 Ma, and inset the Present Tethyan Realm. Credit: ©Science China Press</td></tr>
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Plate tectonics was founded in the late 1960s, and it concerns the distribution and movements of plates, the uppermost layer of the Earth. Plate movements not only control the distributions of earthquakes, volcanoes, and mineral resources in the crust, but also affect the ocean and atmospheric circulations above the crust. Therefore, plate tectonics has been regarded as the fundamental unifying paradigm for understanding the history of Earth.<br />
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Despite the widely accepted kinematics of plate tectonics, the driving force of plate tectonics is still one of the most challenging problems since the birth of this theory. The subduction of oceanic slabs is considered the dominant driving force based on observations of Cenozoic subduction systems along the circum-Pacific region.<br />
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However, the difficulty in observing the oceanic subduction slabs beneath collisional orogens hampers the ability to quantitatively evaluate the role of subducting oceanic slabs. Alternative driving forces such as ridge push, continental slab-pull, plume upwelling and large-scale mantle convection have been proposed at different subduction-collision belts along the Tethyan Realm (Fig 1), the largest continental collisional zone. The Tethyan evolution can be summarized as the process by which many continental fragments were ruptured sequentially from Gondwana and then drift towards Laurasia/Eurasia.<br />
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Scientists from the State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences in Beijing found "switches" between continental rupture, continental collision, and oceanic subduction initiation in the Tethyan evolution after a reappraisal of geological records from the surface and new global-scale geophysical images at depth. They proposed that the "switches" were all controlled by oceanic subductions.<br />
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All oceanic Tethyan slabs acted in a way that transferred the Gondwana-detached continents in the south into the terminal in the north, so they depicted the scenario as a "Tethyan one-way train" (Figure. 2a and b). The engine of the "train" was the negative buoyancy of the subducting oceanic slabs. The results also shed light on supercontinent assembly and breakup cycles. Subductions not only assemble the supercontinent but also effectively break-up the supercontinent.<br />
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The new results will not close the discussions on driving force of plate tectonics, but future Tethyan research may test the new proposal and improve the understanding of how plate tectonics works.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-flVzt8375eM/XW6T0jMGkJI/AAAAAAAARYM/2Dkn-aTHNm0u-VPKjzALQ3aPnC1DSNaswCLcBGAs/s1600/1-whatdrivespl%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="803" data-original-width="1206" height="426" src="https://1.bp.blogspot.com/-flVzt8375eM/XW6T0jMGkJI/AAAAAAAARYM/2Dkn-aTHNm0u-VPKjzALQ3aPnC1DSNaswCLcBGAs/s640/1-whatdrivespl%2B%25281%2529.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A schematic showing how subduction drives the 'Tethyan One-way Train' between terminals of Gondwana and Eurasia. a. After consumption of mid-ocean ridge, subduction dragging causes the rift of the rear continent. b. Drifts of the detached continent will finally collide toward the subduction-directed continent, and then continental collision induces subduction initiation in a new ocean. Since the oceanic subduction initiation, the mid-ocean ridge will be consumed towards the subduction direction then repeat the process of 'a'. The light to dark belt represents oceanic crust with ages from young to old. Credit: ©Science China Press</td></tr>
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<br />
<i><u><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://link.springer.com/article/10.1007%2Fs11430-019-9393-4" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.springer.com/societies+&+publishing+partners/chinese+library+of+science/science+in+china+press?SGWID=0-169002-0-0-0" rel="nofollow" target="_blank">Science China Press.</a></span></u></i></div>

What Drives Plate Tectonics?

Global paleomagnetic plate reconstructions a. 270 Ma, b. 180 Ma, and inset the Present Tethyan Realm. Credit: ©Science China Press Pl...

Scientists Confirm The Discovery of a Mineral Never Before Seen in Nature

Geochemistry, Meteorite, Mineralogy 7:53 PM

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<tr><td class="tr-caption" style="text-align: center;">Inside the Wedderburn meteorite. Source: Rodney Start/Museums Victoria</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;"> Mineral 'NEVER seen before in nature' is discovered inside a meteorite in Australia, scientists claim</span><br />
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It was found along the side of a road in a remote Australian gold rush town. In the old days, Wedderburn was a hotspot for prospectors – it occasionally still is – but nobody there had ever seen a nugget quite like this one.<br />
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The Wedderburn meteorite, found just north-east of the town in 1951, was a small 210-gram chunk of strange-looking space rock that fell out of the sky. For decades, scientists have been trying to decipher its secrets, and researchers just decoded another.<br />
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In a new study led by Caltech mineralogist Chi Ma, scientists analysed the Wedderburn meteorite and verified the first natural occurrence of what they call 'edscottite': a rare form of iron-carbide mineral that's never been found in nature.<br />
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Named after the Australian town that it was found in, back in 1951, the Wedderburn meteorite has unveiled a new side: a mineral that has never been seen naturally on Earth has been founded inside it. <br />
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The mineral has been named 'edscottite Fe<sub>5</sub>C<sub>2</sub>,' after Edward Scott, a renowned cosmochemist from the University of Hawaii.<br />
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The mineral was discovered after a team of researchers from CalTech, lead by mineralogist Chi Ma. They closely examined a segment of what's left of the original 220-gram red and black rock.<br />
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The original meteorite is kept as part of the Museums Victoria's collection in Australia. <br />
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A mineral is an assortment of atoms set into a specific form, and naturally occurring in nature. For example, salt and diamonds are both minerals, one is made of sodium chloride, and the other is made of pure carbon.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">What did the researchers find here?</span></h4>
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Inside the Wedderburn meteorite, the researchers discovered a new mineral. Microscopically, it appears as small white crystals.<br />
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This mineral is a combination of carbon and iron atoms, set together in a particular pattern. "This meteorite had an abundance of carbon in it. And as it slowly cooled down, the iron and carbon came together and formed this mineral," said Dr. Stuart Mills, Museums Victoria's senior curator of geosciences.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">What is new about 'edscottite'?</span></h4>
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A synthetic edscottite has, in fact, been discovered previously - typically found inside smelters. It is a phase that iron goes through while it is smelted into steel. <br />
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The difference here is that edscottite has never been known or discovered to be naturally occurring in nature. Only when minerals are found in nature can they be named.<br />
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This is what makes this discovery so exciting. As Dr. Mills pointed out, "We have discovered 500,000 to 600,000 minerals in the lab, but fewer than 6,000 that nature’s done itself."</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">Wedderburn meteorite's story</span></h4>
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Many scientists have claimed chunks of it over the years in the name of research, and only one-third of the meteorite is still left. Let's see if any more interesting discoveries can be made from the Wedderburn Meteorite.<br />
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The meteorite is believed to have emanated from an old planet, which no longer exists. As it blew apart, meteorites from its core got thrust out into space.<br />
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The Wedderburn meteorite was one such chunk from the blasted planet. It was circling up in space for millions of years, before colliding on Earth, and into the Australian territory.</div>
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The findings are reported in <a href="https://www.degruyter.com/view/j/ammin.2019.104.issue-9/am-2019-7102/am-2019-7102.xml" rel="nofollow" target="_blank">American Mineralogist</a>.</span></i></u></div>

Scientists Confirm The Discovery of a Mineral Never Before Seen in Nature

Inside the Wedderburn meteorite. Source: Rodney Start/Museums Victoria Mineral 'NEVER seen before in nature' is discovered in...

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