#extended period in places on tectonic plates and volcanoes

[aka-indulgence]

Just curious as someone who lives somewhere that experiences semi often earthquakes

(Also you know. Reblog for data set etc)

[badhouseplant]

Aliens visit Yellowstone

I've been following this humans are space orcs tag for a while. I've heard that plate tectonics may be crucial for life. So what if what is weird about humans is not plate tectonics or extreme weather but that we live there often on purpose? Like think of Yellowstone! Imagine the first aliens to visit Earth for an extended period of time. They would see our biggest cities, our oldest settlements, or museums, our art... And then they are invited to visit this Park called Yellowstone. And they get there and find that this park is centered around an ACTIVE VOLCANO! And people have been living and traveling through this area for hundreds of years. And now we have boardwalks over streams of boiling acid, and the park is most famous for a jet of near boiling water and steam. And people get seriously hurt or killed by the boiling acid and the wildlife every YEAR. And still people visit and try to pet the bison! Like these aliens know a lot about volcanoes but there is no way they would visit one! For fun! On purpose! So the aliens are like "Not many people visit this place right?" And their guides are like "No this is our oldest national park and it is one of the most visited parks in this particular country! In fact so many people visit that most of the people that work here are employed protecting the park." The aliens are like "Protecting the volcano from WHAT??" "Well, from other humans, of course." Aliens leave Earth soon after and warn every species they can think of that humans are not only short-sighted but also so dangerous that they have people who are employed protecting volcanoes from other people!

[mitchbattros]

Mantle Rock Behind Yellowstone's Supereruptions Extends To Northern California

Victor Camp has spent a lifetime studying volcanic eruptions all over the world, starting in Saudi Arabia, then Iran, and eventually the Pacific Northwest. The geology lecturer finds mantle plumes that feed the largest of these eruptions fascinating, because of their massive size and the impact they can have on our environment.

Over the past two years, this abiding interest helped him connect the dots and discover that the mantle source rock that rises upward from beneath Yellowstone National Park to feed its periodic supereruptions also spreads out west all the way to Northern California and Oregon. On its westward journey, it acts as the catalyst for fairly young—meaning less than 2 million years old—volcanic eruptions at places such as Craters of the Moon National Monument and Preserve in Idaho, before reaching Medicine Lake Volcano in the northeastern tip of California, close to the Oregon border. The mantle rock spreads laterally through narrow flow-line channels well below the earth's crust for over 500 miles, bifurcating twice: once as it leaves Yellowstone and again as it reaches the California-Oregon border. These lines end at Medicine Lake, an active volcano near Mount Shasta, and at Newberry Volcano, an active volcano about 20 miles south of Bend, Ore. This discovery is significant because it reveals how mantle plumes similar to the one beneath Yellowstone behave as they feed the majority of the world's largest volcanic eruptions of basaltic lava, including the ones in Hawaii. "Since the plume is not controlled by plate tectonics, it can rise and emerge anywhere on earth, depending on where it manages to break through the earth's surface," Camp said. "So, knowing this will help us understand supereruptions that have occurred before, and those that will occur in the future." The results of his self-funded study were published in the journal Geology in May. Mantle plumes are composed of very hot, low-density mantle rock. Mantle is one of three major layers of planet earth—we live on the earth's crust, the thinnest layer, and mantle is the second denser layer that extends from about 100 kilometers (62 miles) below the earth's surface all the way down to about 2,700 kilometers (about 1,680 miles), and further down is the core of the earth comprised mostly of iron mixed with a few other elements. Mantle plumes are technically mantle rock, but because they are hotter and more buoyant than surrounding mantle they rise in a plume-like form. When the Yellowstone plume first reached the base level of the North American tectonic plate, it was blocked by the rigidity of the cold plate base which acted as a barrier. At this depth of about 100 kilometers, the plume began to decompress and melt, while simultaneously spreading laterally to the west. The mantle rock that Camp traced to California took many millions of years to move out west. What's interesting is that the source of the mantle rock under Yellowstone today originated at the core-mantle boundary geographically centered near present-day San Diego, but very deep beneath the earth's surface we reside on—and took a circuitous route through different regions of the mantle before it rose up underneath the Yellowstone volcano. Camp sourced seismic tomography images, similar to X-rays and CT-scans (computerized tomography scans), that show how the mantle plume ascended, and he analyzed field data as well as published chemistry and age data on volcanic rocks at the surface, to demonstrate its westward flow. Read the full article

[fumpkins]

Rise of carbon dioxide–absorbing mountains in tropics may set thermostat for global climate | Science

In some wet tropical mountains, carbon dioxide is captured and flushed out of the atmosphere.

Robert Harding/Alamy Stock Photo

Hate the cold? Blame Indonesia. It may sound odd, given the contributions to global warming from the country’s 270 million people, rampant deforestation, and frequent carbon dioxide (CO2)-belching volcanic eruptions. But over much longer times, Indonesia is sucking CO2 out of the atmosphere.

Many mountains in Indonesia and neighboring Papua New Guinea consist of ancient volcanic rocks from the ocean floor that were caught in a colossal tectonic collision between a chain of island volcanoes and a continent, and thrust high. Lashed by tropical rains, these rocks hungrily react with CO2 and sequester it in minerals. That is why, with only 2% of the world’s land area, Indonesia accounts for 10% of its long-term CO2 absorption. Its mountains could explain why ice sheets have persisted, waxing and waning, for several million years (although they are now threatened by global warming).

Now, researchers have extended that theory, finding that such tropical mountain-building collisions coincide with nearly all of the half-dozen or so significant glacial periods in the past 500 million years. “These types of environments, through time, are what sets the global climate,” said Francis Macdonald, a geologist at the University of California, Santa Barbara, when he presented the work last month at a meeting of the American Geophysical Union in Washington, D.C. If Earth’s climate has a master switch, he suggests, the rise of mountains like Indonesia’s could be it.

Most geologists agree that long-term changes in the planet’s temperature are governed by shifts in CO2, and that plate tectonics somehow drives those shifts as it remakes the planet’s surface. But for several decades, researchers have debated exactly what turns the CO2 knob. Many have focused on the volcanoes that rise where plates dive beneath one another. By spewing carbon from Earth’s interior, they could turn up the thermostat. Others have emphasized rock weathering, which depends on mountain building driven by plate tectonics. When the mountains contain seafloor rocks rich in calcium and magnesium, they react with CO2 dissolved in rainwater to form limestone, which is eventually buried on the ocean floor. Both processes matter; “the issue is which one is changing the most,” says Cin-Ty Lee, a volcanologist at Rice University in Houston, Texas.

Having the right rocks to drive the CO2-chewing reaction is not sufficient. Climate matters, too. For example, the Siberian Traps, a region that saw devastating volcanic eruptions 252 million years ago, are rich in such rocks but absorb little, says Dennis Kent, a geologist at Rutgers University in New Brunswick, New Jersey. “It’s too damn cold,” he says. Saudi Arabia has the heat and the rocks but lacks another ingredient. “It’s hotter than Hades but it doesn’t rain.” Indonesia’s location in the rainy tropics is just right. “That is probably what’s keeping us centered in an ice age,” Kent adds.

Over the past few years, Macdonald and his collaborators have searched for other times when tectonics and climate could have conspired to open an Indonesia-size CO2 drain. They found that glacial conditions 90 million and 50 million years ago lined up neatly with the collisions of a chain of island volcanoes in the now-vanished Neo-Tethys Ocean with the African and Asian continents. A similar collision some 460 million years ago formed the Appalachians, but it was thought to have taken place in the subtropics, where a drier climate does not favor weathering. By reanalyzing ancient magnetic fields in rocks formed in the collision, Macdonald’s team found the mountains actually rose deep in the tropics. And their uplift matched a 2-million-year-long glaciation. “They’re developing a pretty compelling story that this was a climate driver in Earth’s past,” says Lee Kump, a paleoclimatologist at Pennsylvania State University in University Park.

But those cases could be exceptions. So the team compiled a database of every tectonic “suture”—the linear features left by tectonic collisions—known to contain ophiolites, those bits of volcanic sea floor, over the past half-billion years. Based on magnetism in each suture’s rocks and a model of continental drift, they mapped their ancient latitudes to see which formed in the topics, and when. “We were surprised that this is not as complicated as we thought,” Macdonald said.

The team compared the results to records of past glaciations and found a strong correlation. They also looked for declines in volcanism, which might have cooled the climate. But their influence was much weaker, Macdonald said.

Kimberly Lau, a geochemist at the University of Wyoming in Laramie, calls the work “exciting in idea and novel in execution.” Lee, however, would like to see direct evidence from ancient sediments that the collisions drove up rock weathering. “They have to go to the sink and study those,” he says. And a recent study challenges the mountain thermostat idea with evidence for the importance of volcanoes. The study used ages from thousands of zircons, durable crystals that can indicate volcanic activity, to show that upticks in volcanic emissions were the dominant force driving the planet’s warm periods. It’s likely both teams have at least one hand on the truth, adds Lee, who contributed to the zircon paper.

The beauty of his team’s model, Macdonald said at the end of his talk, is that it explains not just why glacial times start, but also why they stop. A hothouse Earth appears to be the planet’s default state, prevailing for three-fourths of the past 500 million years. An Indonesia-style collision may push the global climate into a glacial period, but only for a while. Mountains erode and continents drift. And the planet warms again. 

New post published on: https://www.livescience.tech/2018/12/30/rise-of-carbon-dioxide-absorbing-mountains-in-tropics-may-set-thermostat-for-global-climate-science/