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      Early plate tectonics was surprisingly speedy

      news.movim.eu / ArsTechnica · Wednesday, 16 August, 2023 - 15:30 · 1 minute

    Image of a small person standing in front of large, reddish rocks.

    Enlarge / 2.7-billion-year-old basalt lava flows in the Pilbara Craton, now tilted about 45 degrees from horizontal. (credit: Jennifer Kasbohm )

    Have tectonic plates changed speed over the last three billion years? The answer has far-reaching implications, as plate tectonics affected everything from the supply of vital nutrients for early life to the rise of oxygen . We know Earth’s interior was hotter early in its history, but did plates move faster because the hotter mantle was squishier, or did the hotter mantle contain less water , which helps mantle minerals flow, slowing plates down?

    A new study , led by Dr. Jennifer Kasbohm of Yale, measured ancient magnetic fields and dated rocks from Western Australia to show that the “Pilbara Craton”—an early continent—moved at quite a clip around 2.7 billion years ago. While today’s fastest plate motion is around 12 cm (4.7 in) per year, the Pilbara Craton moved as much as 64 centimeters (25 inches) per year.

    A rare remnant of early Earth

    In the Archean eon, a time far closer to the formation of our Solar System than to today, basalt oozed over what would later be Western Australia in much the same way it does in Iceland and Hawaii today. Plate tectonics was still relatively new , and continents were in the early stages of emerging from what had largely been a water world . The air was devoid of oxygen, and the most advanced life came in the form of microbial communities that are preserved today in hummocky fossils known as “ stromatolites .”

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      Has the century-old mystery of Antarctica’s “Blood Falls” finally been solved?

      news.movim.eu / ArsTechnica · Wednesday, 12 July, 2023 - 17:07 · 1 minute

    Blood Falls seeps from the end of the Taylor Glacier into Lake Bonney

    Enlarge / Blood Falls seeps from the end of the Taylor Glacier into Lake Bonney. Scientists believe a buried saltwater reservoir is partly responsible for the discoloration, which is a form of reduced iron. (credit: NSF/Peter Rejcek/Public domain)

    In 1911, an Australian geologist named Thomas Griffith Taylor was exploring a valley in Antarctica when he stumbled upon a strange waterfall. The meltwater flowing from beneath the glacier that now bears Taylor's name turns a deep red upon coming into contact with the air, earning the site the moniker "Blood Falls." Various hypotheses have been proposed over the last century to explain the strange phenomenon. A team of scientists now thinks they've finally found the answer: tiny nanospheres rich in iron, silica, calcium, aluminum, and sodium, among other elements.

    But why has solving this mystery taken more than a century? It seems the nanospheres are amorphous materials, meaning they lack a crystalline structure and hence eluded prior analytical methods looking for minerals because they are not, technically, minerals, according to a recent paper published in the journal Frontiers in Astronomy and Space Science. That might seem like an odd choice of journal for this study, but the Blood Falls at Taylor Glacier is a so-called "analogue" site for astrobiologists and planetary scientists keen to learn more about how life might evolve and thrive in similar inhospitable environments elsewhere in the universe.

    "With the advent of the Mars Rover missions, there was an interest in trying to analyze the solids that came out of the waters of Blood Falls as if it was a Martian landing site," said co-author Ken Livi of Johns Hopkins University. "What would happen if a Mars Rover landed in Antarctica? Would it be able to determine what was causing the Blood Falls to be red? It's a fascinating question and one that several researchers were considering."

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      Nuclear Waste Borehole Demonstration Center started

      news.movim.eu / ArsTechnica · Friday, 17 March, 2023 - 17:44 · 1 minute

    A diagram of what a waste borehole might look like, with various additional objects included for scale.

    Enlarge / An artist’s impression of a deep borehole for nuclear waste disposal by Sandia National Laboratories in 2012. Red lines show the depth of mined repositories: Onkalo is the Finnish one, and WIPP is the US DOE repository for defense waste in New Mexico. (credit: Sandia National Laboratories)

    Deep Isolation , a company founded in 2016 and headquartered in California, launched a “ Deep Borehole Demonstration Center ” on February 27. It aims to show that disposal of nuclear waste in deep boreholes is a safe and practical alternative to the mined tunnels that make up most of today’s designs for nuclear waste repositories.

    But while the launch named initial board members and published a high-level plan, the startup doesn’t yet have a permanent location, nor does it have the funds secured to complete its planned drilling and testing program.

    Although the idea to use deep boreholes for nuclear waste disposal isn’t new , nobody has yet demonstrated it works. The Deep Borehole Demonstration Center aims to be an end-to-end demonstration at full scale, testing everything: safe handling of waste canisters at the surface, disposal, possible retrieval, and eventual permanent sealing deep underground. It will also rehearse techniques for ensuring that eventual underground leaks will not contaminate the surface environment, even many millennia after disposal.

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      All the ways the most common bit of climate misinformation is wrong

      news.movim.eu / ArsTechnica · Wednesday, 15 March, 2023 - 11:00

    Is it natural, or is it us? (It's us.)

    Enlarge / Is it natural, or is it us? (It's us.) (credit: Andriy Onufriyenko/Getty Images)

    It starts as a reasonable question: If the Earth's climate changed before humans existed, how can we be so sure the current change is due to us and not something natural?

    To answer that question, we need to understand what caused the natural changes of the past. Fortunately, science has a good handle on the causes of Earth’s natural climate changes going back hundreds of millions of years. Some were cyclical; others were gradual shifts or abrupt events, but none explain our changing climate today.

    A zombie claim

    With energy policy and elections in the news, the claim by some politicians that climate change is natural is once again bubbling up from the disinformation swamp. So I asked some scientists a very unscientific question: What would they buy if they had a dollar for every time they heard it?

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      This Yellowstone hot spring’s rhythmic thump makes it a geo-thermometer

      news.movim.eu / ArsTechnica · Friday, 10 March, 2023 - 19:23 · 1 minute

    The vibrating water surface of Doublet Pool in Yellowstone National Park. Credit: Jamie Farrell/University of Utah

    Yellowstone National Park is most famous for Old Faithful , a geyser with fairly predictable periodic eruptions that delight visiting tourists. But it's also home to many other geothermal features like Doublet Pool , a pair of hot springs connected by a small neck with the geothermic equivalent of a pulse. The pool "thumps" every 20-30 minutes, causing the water to vibrate and the ground to shake. Researchers at the University of Utah have measured those thumping cycles with seismometers to learn more about how they change over time. Among other findings, they discovered that the intervals of silence between thumps correlate with how much heat is flowing into the pool, according to a new paper published in the journal Geophysical Research Letters.

    “We knew Doublet Pool thumps every 20-30 minutes,” said co-author Fan-Chi Lin , a geophysicist at the University of Utah. “But there was not much previous knowledge on what controls the variation. In fact, I don’t think many people actually realize the thumping interval varies. People pay more attention to geysers.”

    Yellowstone's elaborate hydrothermal system is the result of shallow groundwater interacting with heat from a hot magma chamber. The system boasts some 10,000 geothermal features, including steam vents (fumaroles), mud pots, and travertine terraces (chalky white rock), as well as geysers and hot springs.

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