Earth Has a 27.5-Million-Year 'Heartbeat', But We Have No Idea What Causes It

<p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoLr0jtVZJNd7_wYJ4JT1-OBSngIjnxmw1C4OLfibfs0Myi9qWuiQXa0k4brrLcvG3aGJdEFeTgjdTIWdAa6b06FfptGcSVTdgUcFjbnKm05bAS7CP5hx7XZmkjnupcdP9OAnDRWNCFz-XXdridkpqP8zm-GUeO0A7JYxtJPxCthq8IWzG_4a7O8Ws/s1210/Earth%20Has%20a%2027.5-Million-Year%20'Heartbeat',%20But%20We%20Have%20No%20Idea%20What%20Causes%20It%20(1).jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="680" data-original-width="1210" height="360" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoLr0jtVZJNd7_wYJ4JT1-OBSngIjnxmw1C4OLfibfs0Myi9qWuiQXa0k4brrLcvG3aGJdEFeTgjdTIWdAa6b06FfptGcSVTdgUcFjbnKm05bAS7CP5hx7XZmkjnupcdP9OAnDRWNCFz-XXdridkpqP8zm-GUeO0A7JYxtJPxCthq8IWzG_4a7O8Ws/w640-h360/Earth%20Has%20a%2027.5-Million-Year%20'Heartbeat',%20But%20We%20Have%20No%20Idea%20What%20Causes%20It%20(1).jpg" title="Earth Has a 27.5-Million-Year 'Heartbeat', But We Have No Idea What Causes It" width="640" /></a></div> <br /><p></p><p>In the last 260 million years, dinosaurs came and went, Pangea split into the continents and islands we see today, and humans have quickly and irreversibly changed the world we live in.<br /></p><p>Geologic activity on Earth appears to follow a 27.5-million-year cycle, giving the planet a “pulse,” according to a new study published in the journal Geoscience Frontiers.<br /><br />“Many geologists believe that geological events are random over time. But our study provides statistical evidence for a common cycle, suggesting that these geologic events are correlated and not random,” said Michael Rampino, a geologist and professor in New York University’s Department of Biology, as well as the study’s lead author.<br /><br />Over the past five decades, researchers have proposed cycles of major geological events—including volcanic activity and mass extinctions on land and sea—ranging from roughly 26 to 36 million years. But early work on these correlations in the geological record was hampered by limitations in the age-dating of geologic events, which prevented scientists from conducting quantitative investigations.<br /></p><div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div><br />However, there have been significant improvements in radio-isotopic dating techniques and changes in the geologic timescale, leading to new data on the timing of past events. Using the latest age-dating data available, Rampino and his colleagues compiled updated records of major geological events over the last 260 million years and conducted new analyses.<br /><br />The team analyzed the ages of 89 well-dated major geological events of the last 260 million years. These events include marine and land extinctions, major volcanic outpourings of lava called flood-basalt eruptions, events when oceans were depleted of oxygen, sea-level fluctuations, and changes or reorganization in the Earth’s tectonic plates.<br /><br />They found that these global geologic events are generally clustered at 10 different timepoints over the 260 million years, grouped in peaks or pulses of roughly 27.5 million years apart. The most recent cluster of geological events was approximately 7 million years ago, suggesting that the next pulse of major geological activity is more than 20 million years in the future.<br /><br />The researchers posit that these pulses may be a function of cycles of activity in the Earth's interior—geophysical processes related to the dynamics of plate tectonics and climate. However, similar cycles in the Earth’s orbit in space might also be pacing these events.<br /><br />“Whatever the origins of these cyclical episodes, our findings support the case for a largely periodic, coordinated, and intermittently catastrophic geologic record, which is a departure from the views held by many geologists,” explained Rampino.<br /><br />In addition to Rampino, study authors include Yuhong Zhu of NYU’s Center for Data Science and Ken Caldeira of the Carnegie Institution for Science. <p></p><p><br /></p><p><br /><u><i>The above story is based on <a href="https://www.nyu.edu/about/news-publications/news/2021/june/earth-pulse.html" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.nyu.edu/nyu/en.html" rel="nofollow" target="_blank">New York University</a> .</i></u><br /></p>

Earth Has a 27.5-Million-Year 'Heartbeat', But We Have No Idea What Causes It

  In the last 260 million years, dinosaurs came and went, Pangea split into the continents and islands we see today, and humans have quickly...

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Scientists Map Yellowstone’s Underground ‘Plumbing’

<p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdsWrhhidFMrrUCAriK8FpjzgrX1zWP54XHQQ8_6wmlUPJOWdQZ9igCPRtP69Yr7f0PUmilzHoJLdCej2wpiyP7aczXyPI8ed6awCdzXe83R_-ctvo2K1Xi6VAzhvIfUvGV5Vb6gpLWAhYpA42nfwbTa04NxakuQ-ZfUt5CylorvY8X58UXB8RUFXf/s1200/0_Yellowstone-eruption-illustration%20(1).jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1027" data-original-width="1200" height="548" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdsWrhhidFMrrUCAriK8FpjzgrX1zWP54XHQQ8_6wmlUPJOWdQZ9igCPRtP69Yr7f0PUmilzHoJLdCej2wpiyP7aczXyPI8ed6awCdzXe83R_-ctvo2K1Xi6VAzhvIfUvGV5Vb6gpLWAhYpA42nfwbTa04NxakuQ-ZfUt5CylorvY8X58UXB8RUFXf/w640-h548/0_Yellowstone-eruption-illustration%20(1).jpg" title="Researchers mapped the national park's hydrothermal 'plumbing system' using a giant flying magnet." width="640" /></a></div> <br /><p></p><ul style="text-align: left;"><li><span style="font-family: georgia;">Hidden Channels Beneath Yellowstone Have Been Revealed For The First Time</span></li><li><span style="font-family: georgia;">Researchers mapped the national park's hydrothermal 'plumbing system' using a giant flying magnet.</span></li></ul><p><br />The subterranean "plumbing system" of superheated water that feeds Yellowstone National Park's geysers and other hydrological features has been mapped out in stunning detail — and the findings could fill a major knowledge gap that experts have described as a "mystery sandwich." <br /><br />The geysers and fumaroles of Yellowstone National Park are among the most iconic and popular geological features on our planet. Each year, millions of visitors travel to the park to marvel at the towering eruptions of Old Faithful, the bubbling mud cauldrons of Artists Paint Pots, the crystal-clear water and iridescent colors of Grand Prismatic Spring, and the stacked travertine terraces of Mammoth Hot Springs.<br /><br />Those who have visited the park may have asked themselves, “Where does all the hot water come from?” A study published this week in Nature, co-authored by Virginia Tech’s W. Steven Holbrook and colleagues from the U.S. Geological Survey and Aarhus University in Denmark, provides stunning subsurface images that begin to answer that question.<br /><br />The research team used geophysical data collected from a helicopter to create images of Yellowstone’s subsurface “plumbing” system. The method detects features with unusual electrical and magnetic properties indicative of hydrothermal alteration.<br /></p><div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div><br />“The combination of high electrical conductivity and low magnetization is like a fingerprint of hydrothermal activity that shows up very clearly in the data,” said Holbrook, a professor of geophysics and head of the Department of Geosciences in Virginia Tech’s College of Science. “The method is essentially a hydrothermal pathway detector.”<br /><br />Images from the study show that the park’s geology profoundly shapes its hot springs. Hot hydrothermal fluids ascend nearly vertically, from depths of more than 1 km (or .62 miles), to arrive at the park’s major hydrothermal fields. Along the way, they mix with shallower groundwater flowing within and beneath the park’s volcanic lava flows, which also are visible in the images. Faults and fractures guide the ascent of hydrothermal waters, while lava flow boundaries control the shallow groundwater aquifers.<br /><br />The project fills in a longstanding knowledge gap about the underpinnings of Yellowstone’s charismatic hydrothermal features. Much is known about the park’s surface hydrothermal features, including the chemistry and temperature of mud pots and springs, the eruption interval of geysers, and the unique thermophilic bacteria that live in and around those features.<br /><br />Likewise, scientists have a growing body of knowledge about the deeper heat sources and tectonic activity by tracking earthquakes that occur there. But little is known about how the surface hydrothermal features are connected to each other and to the deeper sources of heat and fluids.<br /><br />“Our knowledge of Yellowstone has long had a subsurface gap,” Holbook said. “It’s like a ‘mystery sandwich’ — we know a lot about the surface features from direct observation and a fair amount about the magmatic and tectonic system several kilometers down from geophysical work, but we don’t really know what’s in the middle. This project has enabled us to fill in those gaps for the first time.”<br /><br />To collect the data, the team used a unique instrument called “SkyTEM” that consists of a large loop of wire towed beneath a helicopter. As the helicopter flies, the loop sends downward repeated electromagnetic signals that provoke a response from electrically conductive bodies in the subsurface.<br /><br />That response is recorded and later analyzed to produce detailed cross-sections along the flight lines. The technique is highly effective in environments like Yellowstone: hydrothermal fluids alter the rocks they pass through, turning rock into clay minerals — for example, the surface mud pots — that have heightened electrical conductivity but suppressed magnetization.<br /><br />Because the helicopter is able to travel at speeds of 40 to 50 mph while towing the SkyTEM instrument, scientists involved in the study were able to cover large swaths of the sprawling, 3,500-square-mile national park, Holbrook said.<br /><br />“One of the unique aspects of this dataset is its extensive coverage of this huge system,” Holbrook added. “We were able not just to look deep beneath the hydrothermal features, but also to see how adjacent features might be connected in the subsurface across great distances. That’s never been possible before.”<br /><br />One of the mysteries addressed by the new work is whether different hydrothermal areas in the park show contrasting deep fluid sources and pathways. The team found a remarkable similarity in the deep structure beneath areas such as Norris Geyser Basin and Lower Geyser Basin, suggesting that contrasts in the chemistry and temperatures of those areas are not caused by deep processes. Instead, variable degrees of mixing with shallow groundwater likely create the wide variety of hot spring characteristics in the park.<br /><br />Overall, the project generated more than 2,500 miles of helicopter lines, an enormous amount of data, according to Holbrook. Upon the study’s publication last month, the research team released the data so that others can undertake additional research.<br /><br />“The data set is so big that we’ve only scratched the surface with this first paper,” Holbrook added. “I look forward to continuing to work on this data and to seeing what others come up with, too. It’s going to be a data set that keeps on giving.”<br /><br />Before coming to Virginia Tech in 2017, Holbrook was part of the Department of Geology and Geophysics at the University of Wyoming in Laramie, Wyoming. He also co-directed the Wyoming Center for Environmental Hydrology and Geophysics. He said, “I’ve made several field trips to collect ground-based geophysical data in Yellowstone. The airborne data covers a lot more ground much more quickly than we could by hiking gear into the backcountry, though.”<br /><br />Carol Finn of the U.S. Geological Survey and lead author on the study said, “While the airborne data were still being collected, we saw the first images over Old Faithful and knew instantly that our experiment had worked — that we could, for the first time, image the fluid pathways that had long been speculated.”<br /><br />She added, “Our work has sparked considerable interest across a range of disciplines, including biologists looking to link areas of groundwater and gas mixing to regions of extreme microbiological diversity, geologists wanting to estimate volumes of lava flows, and hydrologists interested in modeling flow paths of groundwater and thermal fluid. With the paper as a guide and the release of the data and models, we will enable research in these diverse scientific communities.”<br /><br />One mystery that Holbrook is interested in pursuing further is evidence for distant connections between isolated surface hydrothermal areas. The SkyTEM data show evidence for subsurface linkages between hydrothermal systems that are up to 6 miles apart.<br /><br />“That might have implications for the co-evolution of thermophilic bacteria and Archaea,” Holbrook said. “The notion that airborne geophysical data could illuminate something about the life of microscopic organisms living around hot springs is a fascinating idea.”<p></p><p> </p><p><u>The above story is based on <a href="https://vtx.vt.edu/articles/2022/03/science-yellowstone_hydrothermal_study_holbrook.html" rel="nofollow" target="_blank">materials </a>provided by <a href="https://vtx.vt.edu/" rel="nofollow" target="_blank">Virginia Polytechnic Institute and State University. </a></u><br /></p>

Scientists Map Yellowstone’s Underground ‘Plumbing’

  Hidden Channels Beneath Yellowstone Have Been Revealed For The First Time Researchers mapped the national park's hydrothermal 'plu...

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Tiny Magnetic Waves Have Been Discovered in Earth’s Core

<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZNNjf4Rc0W4Y0qZNiUIbX0R5Ta4CsAj-I4ucuQLezASUtcYi0SuAW-qb98VpVFrqBitNE6g6J04zxtP2Qc7lf0wsyiec95Ghi77LN5P2L0o3V3m7LRdhgvGJvSktjHAX38xxTjo-SiSiG0bjMY3dBZmgUhEqxhAZN7kblUVgdM3Uw3b2NOd1vlpcA/s1220/nonaxisymmetric-waveli%20(1)%20(1).jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="709" data-original-width="1220" height="372" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZNNjf4Rc0W4Y0qZNiUIbX0R5Ta4CsAj-I4ucuQLezASUtcYi0SuAW-qb98VpVFrqBitNE6g6J04zxtP2Qc7lf0wsyiec95Ghi77LN5P2L0o3V3m7LRdhgvGJvSktjHAX38xxTjo-SiSiG0bjMY3dBZmgUhEqxhAZN7kblUVgdM3Uw3b2NOd1vlpcA/w640-h372/nonaxisymmetric-waveli%20(1)%20(1).jpg" title="Tiny Magnetic Waves Have Been Discovered in Earth’s Core" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Diagram showing wave-like flow at the surface of Earth’s outer core and background magnetic field lines. Photo: Felix Gerick<br /><br /></td></tr></tbody></table><br /><span style="font-family: georgia;">Fluctuations in Earth’s magnetic field that repeat every seven years can be used to probe the inner workings of our planet. Small magnetic waves discovered in Earth’s core could help illuminate what is going on deep inside our planet.</span><br /><p></p><p><br /></p><p>A team of researchers from the Royal Observatory of Belgium, Université Savoie Mont Blanc and Institut de Physique du Globe de Paris has identified nonaxisymmetric wavelike patterns in the equatorial region of the Earth's core. In their paper published in Proceedings of the National Academy of Sciences the group describes their study of geomagnetic data obtained from satellites and ground-based observatories over a twenty-year period and describes fluctuations they found beneath the equatorial part of the planet.<br /><br />Prior research has shown that differences in temperature between the Earth's inner core and the outer layer of liquid metal covering it generate a powerful magnetic field. The magnetic field is strong enough to shield the planet from radiation, making life possible. Prior research has also found that the motion of the liquid and the charged particles that it generates is turbulent and random. This explains why Earth's magnetic field varies over time. In this new effort, the researchers sought to learn more about changes to the planet's magnetic field by looking for variations over many years.<br /><br />The researchers acknowledge that the physics involved in changes to the interannual geomagnetic field are still not well understood, though it is known that such variations can extend from several years to hundreds of millions of years. </p><p>To learn more about it, they collected and analyzed geomagnetic data from several satellites and ground-based observatories from the years 1999 to 2021. They found a nonaxisymmetric pattern in the magnetic field around the equatorial part of the planet's core that repeated every seven years with amplitudes reaching as high as 3 km/y. It also moved slowly westward at a rate of approximately 1,500 kilometers each year.<br /><br />In addition to revealing more about the planet's field, the researchers suggest their findings also contradict theories that there is a thin layer of rock below the mantle and above the outer core. They plan to continue their research by attempting to image the geomagnetic field deep inside the core—work that could potentially lead to a means for predicting changes to the field.<br /> </p><p><br /><i><u>The above story is based on <a href="https://pnas.scienceconnect.io/api/oauth/authorize?ui_locales=en&scope=affiliations+login_method+openid+settings&response_type=code&redirect_uri=https%3A%2F%2Fwww.pnas.org%2Faction%2FoidcCallback%3FidpCode%3Dconnect&state=o6Px5SlFGZEdEtpisr1VsXu9ciIaa19hkyOGUp8vqKM&nonce=lmGK4U04s%2Bggb1I1LB6IRmv4NPNnmb%2BMkz6HgNUWazM%3D&prompt=none&client_id=pnas" rel="nofollow" target="_blank">materials </a>provided by  Proceedings of the National Academy of Sciences.</u></i><br /></p>

Tiny Magnetic Waves Have Been Discovered in Earth’s Core

Diagram showing wave-like flow at the surface of Earth’s outer core and background magnetic field lines. Photo: Felix Gerick Fluctuations in...

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Traces of Life in the Earth's Deep Mantle

<p></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhJe-CyorrUuBDxDkDGI8xm_j1rdPtOI4D7lhun4iX78_QWKt6T72T878VNXjsTNgMtN8FXKqd2AaewRUJg1oW2NdpAZBmlYOtwuECy3IxtfxulEh0zmbHLDuy9Aahra7pMsThCJu7hytmgojMC8vyXwL7qT0gxH_cM76ThgSwf95JsybsK0S3Xk1kp=s1080" style="margin-left: auto; margin-right: auto;"><img alt="Traces of Life in the Earth's Deep Mantle" border="0" data-original-height="736" data-original-width="1080" height="436" src="https://blogger.googleusercontent.com/img/a/AVvXsEhJe-CyorrUuBDxDkDGI8xm_j1rdPtOI4D7lhun4iX78_QWKt6T72T878VNXjsTNgMtN8FXKqd2AaewRUJg1oW2NdpAZBmlYOtwuECy3IxtfxulEh0zmbHLDuy9Aahra7pMsThCJu7hytmgojMC8vyXwL7qT0gxH_cM76ThgSwf95JsybsK0S3Xk1kp=w640-h436" title="Kimberlites are complex rocks that came to the Earth's surface from great depths. The picture shows a thin section of a carbonate-​rich kimberlite. (Photograph: David Swart / Messengers of the Mantle Exhibition)" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Kimberlites are complex rocks that came to the Earth's surface from great depths. The picture shows a thin section of a carbonate-​rich kimberlite. (Photograph: David Swart / Messengers of the Mantle Exhibition)<br /></td></tr></tbody></table> <br /><p></p><p style="text-align: left;"><span style="font-family: georgia;">The Cambrian Explosion – around 541 million years ago – was when life and organisms really got going on planet Earth. Now new research has revealed how that explosion of life has left behind traces deep within Earth's mantle.</span><br /><br />It is easy to see that the processes in the Earth's interior influence what happens on the surface. For example, volcanoes unearth magmatic rocks and emit gases into the atmosphere, and thus influence the biogeochemical cycles on our planet.<br /><br />What is less obvious, however, is that the reverse is also true: what happens on the Earth's surface effect the Earth's interior - even down to great depths. This is the conclusion reached by an international group of researchers led by Andrea Giuliani, SNSF Ambizione Fellow in the Department of Earth Sciences at ETH Zurich, in a new study published in the journal Science Advances. According to this study, the development of life on our planet affects parts of Earth’s lower mantle.<br /></p><h4 style="text-align: left;">Carbon as a messenger</h4><p style="text-align: left;">In their study, the researchers examined rare diamond-​bearing volcanic rocks called kimberlites from different epochs of the Earth's history. These special rocks are messengers from the lowest regions of the Earth's mantle. Scientists measured the isotopic composition of carbon in about 150 samples of these special rocks. They found that the composition of younger kimberlites, which are less than 250 million years old, varies considerably from that of older rocks. In many of the younger samples, the composition of the carbon isotopes is outside the range that would be expected for rocks from the mantle.<br /></p><div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div><br />The researchers see a decisive trigger for this change in composition of younger kimberlites in the Cambrian Explosion. This relatively short phase - geologically speaking - took place over a period of few tens of million years at the beginning of the Cambrian Epoch, about 540 million years ago. During this drastic transition, almost all of today's existing animal tribes appeared on Earth for the first time. "The enormous increase in life forms in the oceans decisively changed what was happening on the Earth's surface," Giuliani explains. "And this in turn affected the composition of sediments at the bottom of the ocean."<br /><p></p><h4 style="text-align: left;">From the oceans to the mantle and back</h4><p style="text-align: left;">For the Earth's lower mantle, this changeover is relevant because some of the sediments on the seafloor, in which material from dead living creatures is deposited, enter the mantle through plate tectonics. Along the subduction zones, these sediments - along with the underlying oceanic crust - are transported to great depths. In this way, the carbon that was stored as organic material in the sediments also reaches the Earth's mantle. There the sediments mix with other rock material from the Earth's mantle and after a certain time, estimated to at least 200-​300 million years, rise to the Earth's surface again in other places - for example in the form of kimberlite magmas.<br /><br />It is remarkable that changes in marine sediments leave such profound traces, because overall, only small amounts of sediment are transported into the depths of the mantle along a subduction zone. "This confirms that the subducted rock material in the Earth's mantle is not distributed homogeneously, but moves along specific trajectories," Giuliani explains.<br /></p><h4 style="text-align: left;">The Earth as a total system</h4><p style="text-align: left;">In addition to carbon, the researchers also examined the isotopic composition of other chemical elements. For example, the two elements strontium and hafnium showed a similar pattern to carbon. "This means that the signature for carbon cannot be explained by other processes such as degassing, because otherwise the isotopes of strontium and hafnium would not be correlated with those of carbon," Giuliani notes.<br /><br />The new findings open the door for further studies. For example, elements such as phosphorus or zinc, which were significantly affected by the emergence of life, could also provide clues as to how processes at the Earth's surface influence the Earth's interior. "The Earth is really a complex overall system," Giuliani says. "And we now want to understand this system in more detail." </p><p style="text-align: left;"><br /></p><p style="text-align: left;"><u><i>The above story is based on <a href="https://ethz.ch/en/news-and-events/eth-news/news/2022/03/traces-of-life-in-the-earths-deep-mantle.html" rel="nofollow" target="_blank">materials </a>provided by <a href="http://www.ethz.ch/" rel="nofollow" target="_blank">Eidgenössische Technische Hochschule Zürich</a>.</i></u><br /></p>

Traces of Life in the Earth's Deep Mantle

Kimberlites are complex rocks that came to the Earth's surface from great depths. The picture shows a thin section of a carbonate-​rich ...

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Geologists Have Closely Analyzed Two Bizarre 'Blobs' Detected Deep Inside Earth

<p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhe2fxMrkdTWLX22oo8DWFAtJa_4iVy8VIE5CiYTN43icUtl9CwLEEnEMvsh2DrqKROsOaIefIqlPF7K5nPeUxK009zi4G9D9gs3s-AKtqh_iZQDVW8Q5FNvgfGCmfG4ifR_Z6r_hoWw-p6ejumfpaW4arBZZeccsIUxC2eDM45rZGPXYc8kEAm1QWX=s1483" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1030" data-original-width="1483" height="444" src="https://blogger.googleusercontent.com/img/a/AVvXsEhe2fxMrkdTWLX22oo8DWFAtJa_4iVy8VIE5CiYTN43icUtl9CwLEEnEMvsh2DrqKROsOaIefIqlPF7K5nPeUxK009zi4G9D9gs3s-AKtqh_iZQDVW8Q5FNvgfGCmfG4ifR_Z6r_hoWw-p6ejumfpaW4arBZZeccsIUxC2eDM45rZGPXYc8kEAm1QWX=w640-h444" title="Geologists Have Closely Analyzed Two Bizarre 'Blobs' Detected Deep Inside Earth" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">A 3D view of the blob in Earth’s mantle beneath Africa, shown by the red-yellow-orange colors. The cyan color represents the core-mantle boundary, blue signifies the surface, and the transparent gray signifies continents. Image credit: Mingming Li/ASU</td></tr></tbody></table> <br /></p><p>Earth's interior is not a uniform stack of layers. Deep in its thick middle layer lie two colossal blobs of thermo-chemical material.<br /><br /><br />Earth is layered like an onion, with a thin outer crust, a thick viscous mantle, a fluid outer core and a solid inner core. Within the mantle, there are two massive blob-like structures, roughly on opposite sides of the planet. The blobs, more formally referred to as Large Low-Shear-Velocity Provinces (LLSVPs), are each the size of a continent and 100 times taller than Mt. Everest. One is under the African continent, while the other is under the Pacific Ocean.<br /><br />Using instruments that measure seismic waves, scientists know that these two blobs have complicated shapes and structures, but despite their prominent features, little is known about why the blobs exist or what led to their odd shapes.<br /><br />Arizona State University scientists Qian Yuan and Mingming Li of the School of Earth and Space Exploration set out to learn more about these two blobs using geodynamic modeling and analyses of published seismic studies. Through their research, they were able to determine the maximum heights that the blobs reach and how the volume and density of the blobs, as well as the surrounding viscosity in the mantle, might control their height. Their research was recently published in Nature Geoscience.<br /><br />The results of their seismic analysis led to a surprising discovery that the blob under the African continent is about 621 miles (1,000 km) higher than the blob under the Pacific Ocean. According to Yuan and Li, the best explanation for the vast height difference between the two is that the blob under the African continent is less dense (and therefore less stable) than the one under the Pacific Ocean.<br /><br />To conduct their research, Yuan and Li designed and ran hundreds of mantle convection models simulations. They exhaustively tested the effects of key factors that may affect the height of the blobs, including the volume of the blobs and the contrasts of density and viscosity of the blobs compared with their surroundings. They found that to explain the large differences of height between the two blobs, the one under the African continent must be of a lower density than that of the blob under the Pacific Ocean, indicating that the two may have different composition and evolution.<br /><br />“Our calculations found that the initial volume of the blobs does not affect their height,” lead author Yuan said. “The height of the blobs is mostly controlled by how dense they are and the viscosity of the surrounding mantle.”<br /><br />“The Africa LLVP may have been rising in recent geological time,” co-author Li added. “This may explain the elevating surface topography and intense volcanism in eastern Africa.”<br /><br />These findings may fundamentally change the way scientists think about the deep mantle processes and how they can affect the surface of the Earth. The unstable nature of the blob under the African continent, for example, may be related to continental changes in topography, gravity, surface volcanism and plate motion.<br /><br />“Our combination of the analysis of seismic results and the geodynamic modeling provides new insights on the nature of the Earth’s largest structures in the deep interior and their interaction with the surrounding mantle,” Yuan said. “This work has far-reaching implications for scientists trying to understand the present-day status and the evolution of the deep mantle structure, and the nature of mantle convection.”  </p><p><br /><i><u>The above story is based on <a href="https://news.asu.edu/20220310-study-two-blobs-earths-mantle-shows-unexpected-differences-height-and-density" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.asu.edu/" rel="nofollow" target="_blank">Arizona State University.</a></u></i><br /></p>

Geologists Have Closely Analyzed Two Bizarre 'Blobs' Detected Deep Inside Earth

A 3D view of the blob in Earth’s mantle beneath Africa, shown by the red-yellow-orange colors. The cyan color represents the core-mantle bou...

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Emmonsite Crystal Spray

<p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2wUSRAjRGl1S7WpF3aChWWueNfeHdqgR5O7Gtpo-cyah3fVFxaYW8wFI0bF4Y1E1TWjgoLbA_2jhHzEplCAbGxRZ7OZljIn6wgKqwBvalTATZvEKp1CLfrcWnPHrt6d0bbdmZ2hNnmJDtXVaMa5tA8II1Z7kLROfHDKn8SoxDPGGxxFiJJGsnlM5T/s1024/Emmonsite.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Emmonsite crystals" border="0" data-original-height="1024" data-original-width="1013" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2wUSRAjRGl1S7WpF3aChWWueNfeHdqgR5O7Gtpo-cyah3fVFxaYW8wFI0bF4Y1E1TWjgoLbA_2jhHzEplCAbGxRZ7OZljIn6wgKqwBvalTATZvEKp1CLfrcWnPHrt6d0bbdmZ2hNnmJDtXVaMa5tA8II1Z7kLROfHDKn8SoxDPGGxxFiJJGsnlM5T/w634-h640/Emmonsite.jpg" title="Emmonsite" width="634" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Emmonsite crystal spray from the Moctezuma Mine, Moctezuma, Municipio de Moctezuma, Sonora, Mexico. Photo: Christian Rewitzer<br /></td></tr></tbody></table> <br /></p><p>Emmonsite was first described in 1885 for an occurrence in the Tombstone District, Cochise County, Arizona. It was named for the American geologist, Samuel Franklin Emmons, (1841–1911), of the United States Geological Survey.<br /></p><p>Emmonsite is found, often with quartz or cerussite in the Tombstone, Arizona area. It is also associated with native tellurium, tellurite, native gold, pyrite, rodalquilarite, mackayite, sonoraite, cuzticite and eztlite.<br /><br />Occurrence: An alteration product formed from earlier tellurium minerals in the oxide zone of some hydrothermal precious metal deposits. </p><p><span style="font-size: small;"><span style="font-family: georgia;"><b>Formula: </b><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; display: inline !important; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Fe</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">2</sub><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; display: inline !important; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">(TeO</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">3</sub><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; display: inline !important; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">)</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">3</sub><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; display: inline !important; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">·2(H</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">2</sub><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; display: inline !important; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">O)<br /><b>Color:</b> Yellowish-green; light yellow-green in transmitted light.<br /><b>Crystal system:</b> Triclinic<br /><b>Crystal habit: </b>in rosettes and sprays; in fibrous globular aggregates and crusts, microcrystalline massive.<br /><b>Mohs scale hardness:</b>    5<br /></span></span></span></p>

Emmonsite Crystal Spray

Emmonsite crystal spray from the Moctezuma Mine, Moctezuma, Municipio de Moctezuma, Sonora, Mexico. Photo: Christian Rewitzer   Emmonsite wa...

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110-million-year-old Lizard Rhetinosaurus Found in Amber

<p></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgDBZSuSHBlUsgrxteWGc1sLrl-ZYw0zoJOoaMP_kwXc8fAgIZGvvx8G_a84HkK1mmOawzKvmPvJqjomH2CSVObHi4lM8UsbQJdSJ1mo3HXuKIVfMoP-e-5JqxkNj8UMGZseEiKmvaWDwdqnlKe9lQI2VpMUQvCzLxffEdtbFMfA4ucIguUe4l96REb=s1220" style="margin-left: auto; margin-right: auto;"><img alt="General view of Retinosaurus hkamtiensis: (a) photograph of the specimen" border="0" data-original-height="686" data-original-width="1220" height="360" src="https://blogger.googleusercontent.com/img/a/AVvXsEgDBZSuSHBlUsgrxteWGc1sLrl-ZYw0zoJOoaMP_kwXc8fAgIZGvvx8G_a84HkK1mmOawzKvmPvJqjomH2CSVObHi4lM8UsbQJdSJ1mo3HXuKIVfMoP-e-5JqxkNj8UMGZseEiKmvaWDwdqnlKe9lQI2VpMUQvCzLxffEdtbFMfA4ucIguUe4l96REb=w640-h360" title="110-million-year-old Lizard Rhetinosaurus Found in Amber" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">General view of Retinosaurus hkamtiensis: (a) photograph of the specimen<br /> credit: Čerňanský et al<br /></td></tr></tbody></table> <br /><p></p><p><span style="font-family: georgia;">Paleontologists have found a new species of lizard in a piece of amber excavated from a mine in Myanmar.</span><br /></p><p>Juan Diego Daza, associate professor in Sam Houston State University’s Department of Biological Sciences, is co-author of a new study that involves the discovery a new species of fossil lizard.<br /><br />Published recently in Scientific Reports, the collaborative research describes the first definite representative of a group of lizards known as scincoideans, a group that today includes skinks, Armored Lizards, and Night Lizards, or xantusiids. Intriguingly, the fossil most closely resembles xantusiids, which are today found only the American southwest, Central America and Cuba, half a world away from Myanmar.<br /><br />According to Daza, this new fossil lizard resembles xantusiids in some morphological features, notably the arrangement of its scales which, along with parts of the skeleton, have been preserved in the amber. Even the delicate eyelids are visible, revealing a difference from modern Night Lizards, in which the eyelids are fused into a transparent scale, as in snakes.<br /><br />“We had the rare opportunity of studying the articulated skeleton, but also describing the external appearance of the lizard (scalation), in the same way that herpetologists (amphibian and reptile specialists) study modern species,” Daza said.<br /></p><div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div><br />The resemblance of this fairly complete specimen to modern xantusiids suggests that the new fossil lizard, like modern xantusiids, may have been active in cryptic microhabitats such as rock crevices or under logs.<br /><br />The specimen was found in Myanmar’s Hkamti District in a mine located about 100 kilometers from the more famous mines of the Hukawng Basin which have yielded most of the previously described fossil vertebrates from Myanmar. The new mine is also older by 10 million years, placing these fossils in the Early Cretaceous.<br /><br />The fossil was found in 2017 by local researcher, Burmese gemologist Nyi Nyi Aung who was working with Adolf Peretti from GRS Gemresearch, the curator of the Peretti Museum Foundation (a Swiss institution dedicated to Burmite research), where the specimen now resides. Together they recognized the scientific significance of the specimen, which was recovered from among the hundreds of thousands of amber pieces from the Khamti region recovered by indigenous miners. The specimen has travelled around the world to access the latest imaging technology, including the High-Resolution X-Ray CT Facility in Austin, Texas and the Australian Nuclear Science and Technology Organisation.<br /><br />With the data generated in these facilities, the fossil could be studied in great detail by an international collaboration of researchers from Myanmar, the United Kingdom, Spain, Slovakia, Canada, USA, Argentina, and Australia. 3D data from the CT analysis is freely available to other researchers, educators and the general public.<p></p><p>The results show that Retinosaurus hkamtiensis is a representative of Scincoidea, a superfamily that today includes skinks, armored lizards and night lizards.<br /><br />“The analysis of molecular data placed the reptile as a relative of Tepexisaurus and Xantusiidae lineages,” the researchers said. “This points to an interesting hypothesis, that the present group known exclusively from North and Central America may have originated elsewhere than indicated by their hitherto known biogeography.”<br /><br />“The reason could be an early split in lizard lineages during the Early Cretaceous which would have occured, in this case, somewhere in Gondwana (the Southern continents and India).”<br /><br />“The Burma Terrane microplate (today’s Myanmar) was probably not part of Asia at the time when our lizard lived.” “Back then, the area may have been an island which separated from Australia and traveled northwest.”<br /><br />“The topic is still quite controversial and leaves room for other interpretations of the origin of animal lineages occurring during the Cretaceous in this area,” Dr. Čerňanský concluded.<br /><br />The study was the result of an international team of collaborators lead by Andrej Čerňanský from the Comenius University in Bratislava.</p><p> </p><p><i><u> The above story is based on <a href="https://www.shsu.edu/today@sam/T@S/article/2022/amber-yields-unexpected-find" rel="nofollow" target="_blank">materials </a>provided by<a href="https://www.shsu.edu/" rel="nofollow" target="_blank"> Sam Houston State University.</a></u></i><br /></p>

110-million-year-old Lizard Rhetinosaurus Found in Amber

General view of Retinosaurus hkamtiensis: (a) photograph of the specimen  credit: Čerňanský et al   Paleontologists have found a new species...

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Cetineite Crystals

<p></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-xy7hG4FYVBEfYbrQfNBeOWqPrjQSl11F8BUpgmnKDAlqJ2bForn_7OsAbJtpF7_YHbmXRDjNm6QkAMvoFVfeNJ-3eOYd6-bXk3drzGO-wh9hHnL3BLo8NVRAV805moIb7TEFn6QNQlFm9aBhUvlPaqW7jp548v2Qf8yC31rK4UqZukKtp1LaQnAQ/s1024/Cetineite-203798%20(1).jpeg" style="margin-left: auto; margin-right: auto;"><img alt="Cetineite Crystals" border="0" data-original-height="1022" data-original-width="1024" height="638" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-xy7hG4FYVBEfYbrQfNBeOWqPrjQSl11F8BUpgmnKDAlqJ2bForn_7OsAbJtpF7_YHbmXRDjNm6QkAMvoFVfeNJ-3eOYd6-bXk3drzGO-wh9hHnL3BLo8NVRAV805moIb7TEFn6QNQlFm9aBhUvlPaqW7jp548v2Qf8yC31rK4UqZukKtp1LaQnAQ/w640-h638/Cetineite-203798%20(1).jpeg" title="Cetineite" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Collection and photograph: Christian Rewitzer</td></tr></tbody></table><h4 style="text-align: left;"> <span style="font-size: small;"><span style="font-family: georgia;"><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Cetineite</span></span></span></h4><div style="text-align: left;"><span style="font-family: georgia;"><span style="font-size: small;">A hexagonal-pyramidal mineral containing antimony, hydrogen, oxygen, potassium, sodium, and sulfur. </span></span><br /></div><p></p><div style="text-align: left;"><span style="font-size: small;"><span style="font-family: georgia;"><span style="-webkit-text-stroke-width: 0px; background-color: white; color: black; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 700; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: nowrap; word-spacing: 0px;">Formula: </span></span><span style="font-family: georgia;"><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">(K,Na)</span><sub style="-webkit-text-stroke-width: 0px; background-color: white; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">6</sub><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Sb</span><sup style="-webkit-text-stroke-width: 0px; background-color: white; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 0; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; vertical-align: super; white-space: normal; word-spacing: 0px;">3+</sup><sub style="-webkit-text-stroke-width: 0px; background-color: white; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">12</sub><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">(Sb</span><sup style="-webkit-text-stroke-width: 0px; background-color: white; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 0; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; vertical-align: super; white-space: normal; word-spacing: 0px;">3+</sup><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">S</span><sub style="-webkit-text-stroke-width: 0px; background-color: white; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">3</sub><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">)</span><sub style="-webkit-text-stroke-width: 0px; background-color: white; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">2</sub><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">O</span><sub style="-webkit-text-stroke-width: 0px; background-color: white; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">18</sub><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">(OH)</span><sub style="-webkit-text-stroke-width: 0px; background-color: white; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">0.5</sub><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span> </span>· 5,5H</span><sub style="-webkit-text-stroke-width: 0px; background-color: white; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">2</sub><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">O</span></span></span></div><div style="text-align: left;"><span style="font-size: small;"><span style="font-family: georgia;"><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><b>Colour:</b> Orange-red<br /><b>Lustre: </b>Resinous<br /><b>Hardness:</b> 3½<br /><b>Specific Gravity: </b>4.21 (Calculated)<br /><b>Crystal System: </b>Hexagonal </span></span></span></div><div style="text-align: left;"><span style="font-size: small;"><span style="font-family: georgia;"><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"> </span></span></span></div><div style="text-align: left;"><span style="font-size: small;"><span style="font-family: georgia;"><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Cetineite was named after the Cetine mine in Italy, where it was first discovered. </span></span></span></div><div style="text-align: left;"><span style="font-size: small;"><span style="font-family: georgia;"><span style="-webkit-text-stroke-width: 0px; background-color: white; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: justify; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><b>Locality:</b> Le Cetine di Cotorniano Mine (Le Cetine Mine; Cetine Mine; Rosia), Chiusdino, Siena Province, Tuscany, Italy<br /> </span></span><span style="font-family: georgia;"><span style="-webkit-text-stroke-width: 0px; background-color: white; color: black; display: inline; float: none; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 700; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: nowrap; word-spacing: 0px;"></span></span></span></div>

Cetineite Crystals

Collection and photograph: Christian Rewitzer   Cetineite A hexagonal-pyramidal mineral containing antimony, hydrogen, oxygen, potassium, so...

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A Slow-Motion Section Of San Andreas Fault May Not Be So Harmless After All

<p></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgYGoNTXzzhcrPbG47XJh5uT3Y3ui71uEe6jj6Oc8kDG_nMf3O_6R-_XyPlb3Bt-dGbK4lwNppi7igfH0m32KunSM2Ja0eVfW6D_eOV2UHx9JrJtRhrV_gFQZqpQgE39kOCU4dSP0TtjJRSgp2kjPlSxSEMn8x_sWpMdD0flyPu43GFsu6CS055-M0f=s1170" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="780" data-original-width="1170" height="426" src="https://blogger.googleusercontent.com/img/a/AVvXsEgYGoNTXzzhcrPbG47XJh5uT3Y3ui71uEe6jj6Oc8kDG_nMf3O_6R-_XyPlb3Bt-dGbK4lwNppi7igfH0m32KunSM2Ja0eVfW6D_eOV2UHx9JrJtRhrV_gFQZqpQgE39kOCU4dSP0TtjJRSgp2kjPlSxSEMn8x_sWpMdD0flyPu43GFsu6CS055-M0f=w640-h426" title="A Slow-Motion Section Of San Andreas Fault May Not Be So Harmless After All" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"> San Andreas fault in San Luis Obispo County. Photo: Ricardo DeAratanha</td></tr></tbody></table> <br /><p></p><p>The San Andreas Fault is an 800-mile-long sliding tectonic boundary between the Pacific Plate and the North American Plate. It cleaves California from north to south, as the two tectonic plates slowly grind against each other, threatening to give rise to massive earthquakes. <br /></p><p>Most people have heard about the San Andreas Fault. It’s the 800-mile-long monster that cleaves California from south to north, as two tectonic plates slowly grind against each other, threatening to produce big earthquakes.<br /><br />Lesser known is the fact that the San Andreas comprises three major sections that can move independently. In all three, the plates are trying to move past each other in opposing directions, like two hands rubbing against each other. In the southern and the northern sections, the plates are locked much of the time—stuck together in a dangerous, immobile embrace. This causes stresses to build over years, decades or centuries. Finally a breaking point comes; the two sides lurch past each other violently, and there is an earthquake. However in the central section, which separates the other two, the plates slip past each other at a pleasant, steady 26 millimeters or so each year. This prevents stresses from building, and there are no big quakes. This is called aseismic creep.<br /><br />At least that is the story most scientists have been telling so far. Now, a study of rocks drilled from nearly 2 miles under the surface suggests that the central section has hosted many major earthquakes, including some that could have been fairly recent. The study, which uses new chemical-analysis methods to gauge the heating of rocks during prehistoric quakes, just appeared in the online edition of the journal Geology.<br /><br />“This means we can get larger earthquakes on the central section than we thought,” said lead author Genevieve Coffey, who did the research as a graduate student at Columbia University’s Lamont-Doherty Earth Observatory. “We should be aware that there is this potential, that it is not always just continuous creep.”<br /><br />The threats of the San Andreas are legion. The northern section hosted the catastrophic 1906 San Francisco magnitude 7.9 earthquake, which killed 3,000 people and leveled much of the city. Also, the 1989 M6.9 Loma Prieta quake, which killed more than 60 and collapsed a major elevated freeway. The southern section caused the 1994 M6.7 Northridge earthquake near Los Angeles, also killing about 60 people. Many scientists believe it is building energy for a 1906-scale event.<br /></p><div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div><br />The central section, by contrast, appears harmless. Only one small area, near its southern terminus, is known to produce any real quakes.  There, magnitude 6 events—not that dangerous by most standards—occur about every 20 years. Because of their regularity, scientists hoping to study clues that might signal a coming quake have set up a major observatory atop the fault near the city of Parkfield. It features a 3.2-kilometer-deep borehole from which rock cores have been retrieved, and monitoring instruments above and below ground. It was rock from near the bottom of the borehole that Coffey and her colleagues analyzed.<br /><br />When earthquake faults slip, friction along the moving parts can cause temperatures to spike hundreds of degrees above those of surrounding rocks. This cooks the rocks, altering the makeup of organic compounds in any sedimentary formations along the fault path. Recently, study coauthors Pratigya Polissar and Heather Savage figured out how to take advantage of these so-called biomarkers, using the altered compositions to map prehistoric earthquakes.They say that by calculating the degree of heating in the rock, they can spot past events and estimate how far the fault moved; from this, they can roughly extrapolate the sizes of resulting earthquakes. At Lamont-Doherty, they refined the method in the U.S. Northeast, Alaska, and off Japan.<br /><br />In the new study, the researchers found many such altered compositions in a band of highly disturbed sedimentary rock lying between 3192 and 3196 meters below the surface. In all, they say the blackish, crumbly stuff shows signs of more than 100 quakes. In most, the fault appears to have jumped more than 1.5 meters (5 feet). This would translate to at least a magnitude 6.9 quake, the size of the destructive Loma Prieta and Northridge events. But many could well have been larger, say the researchers, because their method of estimating earthquake magnitude is still evolving. They say quakes along the central section may have been similar to other large San Andreas events, including the one that destroyed San Francisco.<br /><br />The current official California earthquake hazard model, used to set building codes and insurance rates, does include the remote possibility of a big central-section rupture. But inclusion of this possibility, arrived at through mathematical calculations, was controversial, given the lack of evidence for any such prior event. The new study appears to be the first to indicate that such quakes have in fact occurred here. The authors say they could have originated in the central section, or perhaps more likely, started to the north or south, and migrated through the central.<br /><br />So, when did these quakes happen? Trenches dug by paleoseismologists across the central section have revealed no disturbed soil layers that would indicate quakes rupturing the surface in the last 2,000 years—about the limit for detection using that method in this region. But 2,000 years is an eye blink in geologic terms. And, the excavations could be missing any number of quakes that might not necessarily have ruptured the surface at specific sites.<br /><br />The researchers used a second new technique to address this question. The biomarkers run along very narrow bands, from microscopic to just a couple of centimeters wide. Just a few inches or feet away, the rock heats only enough to drive out some or all of the gas argon naturally present there. Conveniently for the authors, other scientists have long used the ratio of radioactive potassium to argon, into which potassium slowly decays, to measure the ages of rocks. The more argon compared to potassium, the older the rock. Thus, if some or all of the argon is driven out by quake-induced heat, the radioactive “clock” gets reset, and the rock appears younger than identical nearby rock that was not heated.<br /><br />This is exactly what the team found. The sediments they studied were formed tens of millions of years ago in an ancient Pacific basin that was subducted under California. Yet the ages of rocks surrounding the thin quake slip zones came out looking as young as 3.2 million years by the potassium-argon clock. This sets out a time frame, but only a vague one, because the scientists still do not know how to judge the amount of argon that was driven out, and thus how thoroughly the clock may have been reset. This means that 3.2 million years is just an upper age limit for the most recent quakes, said Coffey; in fact, some could have taken place as little as a few hundred or a few thousand years ago, she said. The group is now working on a new project to refine the age interpretations.<br /><br />“Ultimately, our work points to the potential for higher magnitude earthquakes in central California and highlights the importance of including the central [San Andreas Fault] and other creeping faults in seismic hazard analysis,” the authors write.<br /><br />William Ellsworth, a geophysicist at Stanford University who has led research at the drill site, pointed out that while a possible big quake is included in the state’s official hazard assessment, “Most earthquake scientists think that they happen rarely, as tectonic strain is not accumulating at significant rates, if at all, along it at the present time,” he said.<br /><br />Morgan Page, a seismologist with the U.S. Geological Survey who coauthored the hazard assessment, said the study breaks new ground. “The creeping section is a difficult place to do paleoseismology, because evidence for earthquakes can be easily erased by the creep,” she said. “If this holds up, this is the first evidence of a big seismic rupture in this part of the fault.” She said that if a big earthquake can tear through the creeping section, it means that it is possible—though chances would be remote—that one could start at the very southern tip of the San Andreas, travel through the central section and continue all the way on up to the end of the northern section—the so-called “Big One” that people like to speculate about. “I’m excited about this new evidence, and hope we can use it to better constrain this part of our model,” she said.<br /><br />How much should this worry Californians? “People should not be alarmed,” said Lamont-Doherty geologist and study coauthor Stephen Cox.  “Building codes in California are now quite good. Seismic events are inevitable. Work like this helps us figure out what is the biggest possible event, and helps everyone prepare.”<p></p><p> </p><p><u><i><span style="font-family: times;"> The above story is based on <a href="https://news.climate.columbia.edu/2022/02/28/a-slow-motion-section-of-the-san-andreas-fault-may-not-be-so-harmless-after-all/" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.columbia.edu/" style="-webkit-text-stroke-width: 0px; box-sizing: border-box; color: #42aff4; font-size: 16px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Columbia University</a><span style="-webkit-text-stroke-width: 0px; color: black; display: inline; float: none; font-size: 16px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">.</span></span></i></u><br /></p>

A Slow-Motion Section Of San Andreas Fault May Not Be So Harmless After All

 San Andreas fault in San Luis Obispo County. Photo: Ricardo DeAratanha   The San Andreas Fault is an 800-mile-long sliding tectonic boundar...

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