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Tuesday, August 2, 2016

Failure to Launch: Andes, Lava Coulée, and Chao Baby!

       Geologists from
Heidelberg University have discovered deposits of magma in the Andes sufficient to have set off a super-eruption but which, in fact, did not. 




     Researchers discovered that magma volumes of supervolcanic proportions have been continuously accumulating in the Altiplano-Puna region of the Andes since the last super-eruption nearly 2.9 million years ago. 




     These magmas, however, did not reach the surface to trigger a catastrophic eruption but instead slowly cooled at depth and hardened into plutonic rock, similar to the area we discussed in Russia two weeks ago. The results of the research were published in the journal Geology.




       
      Unlike the pluton they describe, the Chao volcano in northern Chile with a lava coulée (or flow) approximately 14.5 km long in the center of the image above flowed at the surface. The composition of the lava matches that of deposits of adjacent supervolcanic calderas. Chao erupted about 75,000 years ago, but zircon crystals in the lava were already forming in a subterranean magma reservoir for nearly three million years.

     "A supervolcanic eruption spews out more than 1,000 cubic kilometers of magma, which accumulated over time in reservoirs close the earth's surface," explains Dr. Axel Schmitt.

       "In turn, these reservoirs are fed from deeper layers in the earth's crust and the underlying mantle. During an eruption, the overlying rock layers collapse into the empty magma chamber and form depressions, known as calderas, of up to 100 kilometers in diameter." Schmitt indicates that there have been at least seven super-eruptions in the Altiplano-Puna region within the last ten million years, the most recent one about 2.9 million years ago. We don't understand why no further major eruptions have occurred since then and whether the region can now be considered inactive for such events.




      Using samples from five small lava domes in northern Chile and southeast Bolivia, the researchers investigated the most recent eruptions whose chemical composition matches the supervolcanic magmas from the region. They determined the age of very small zircon crystals from these lava flows with the aid of a high-spatial-resolution mass spectrometer. 




      "The mineral zircon forms almost exclusively in magmas, so its age reveals when those magmas were present under the volcano," explains Schmitt. "The astonishing result was that the ages of the zircons measured from all five of the smaller volcanoes extended continuously from the time of the eruption 75,000 years ago back to the last supervolcanic eruption."

     Dr. Schmitt reports that model calculations demonstrated that zircon formation is only possible over such long durations if the inflow of magma amounted to approximately one cubic kilometer over 1,000 years, which is unusually high for a relatively small volcano. The volcanologist explains that the lack of a major volcanic eruption does not necessarily indicate that magmatic activity has come to a complete halt. Perhaps the rise in magma from deeper regions merely slowed during the last 2.9 million years, forming a pluton.

      "However, our results also show that a relatively small increase in the long-term magma recharge from about one to five cubic kilometers in 1,000 years would recreate conditions favoring a catastrophic supervolcanic eruption. A new super-eruption in the Altiplano-Puna region would be possible, but only after a long lead time," said Dr.Schmitt.

Have you ever seen anything so (lava) coulée?
Steph

37 comments:

  1. I thought it was strictly plutonic, and now you present me with a zircon.
    This is so sudden!

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    1. Sudden and slow at the same time ;-).

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  2. Replies
    1. More volcano types:

      Dunce-capped volcanoes” spew ignorance and hate.
      Traffic-conic volcanoes” often outcrop from asphault lines.
      When “Megaphone volcanoes” erupt, spewing “megama,” it’s as if the pep rallyers are forced to eat their shouted-out words.

      LegoWhoWearsHis”MakeAmericaGreatAgain”DunceCapBackward…(AndHeDoesMeanBackward!

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    2. Oh, now that takes all the fun out of it. . .Was anyone really confused?

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    3. Someone still is. I know that for a fact.

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    4. Paul, mea culpa, to the confused (and funny).

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    5. Someone else still is confused. I know that for a fict. I'm even confused about the volcanoes I posted, for Vulcan's sake!

      LegoWhoLikeSpockAndWordWomanIsOneMeaCulpanVulcan

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    6. Fict or fiction, Lego?

      I'll play the Will Shortz game, Lego and Paul >>> What questions do you have for me?

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    7. Pedant's bane is quite funny.
      Know anyone like that?

      I had a boss who'd look for some tiny error to criticize employees. I put my "error" on page 3 of 200 so he'd leave the rest of the paper alone.

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  3. Here's a link that has it all for us: literature, science, volcanoes, feminism, NPR, Syrian refugees (and, for me, "It was a dark and stormy night.").

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    1. 200 years--wow! Sounds like a bit of a dark and stormy night. . .and day.

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  4. Those bug creatures in Rio resemble Theo Jansen's strandbeests. Strandbeests do it even better.

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  5. Replies
    1. The abandoned diesel fuel and PCBs don't worry me. And anthrax can be treated with antibiotics. Smallpox could be a problem, though.

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    2. On the other hand, if Miami were underwater and Greenland lived up to its name, think of the tourism and real estate opportunities!

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    3. Wow, Paul, didn't know ice worms were a thing...I love the internet, but only sometimes (This would be one of them.)

      jan, Peter, Paul, and Mary are always a good way to start the day.

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  6. kakistocracy: Government by the least qualified or most unprincipled citizens. Origin of kakistocracy; Greek kakistos, worst, superlative of kakos, bad; see caco– + –cracy.

    khakistocracy: As above, while wearing green-yellow pants

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  7. Replies
    1. "During pregnancy, cells from the fetus cross the placenta and enter the mother's body" ... says lead author Amy Boddy.

      Can you imagine what a woman with that name, working with breast tissue, must have had to put up with in school?

      Anyway, the article reminds me of that awful t-shirt that says, "Insanity it hereditary -- you get it from your kids".

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    2. It much have been rough for anybody, including Amy Boddy.

      Zoë and I are both wondering what cells I may have passed along from her brother to her.

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  8. Things are not looking so good in Ethiopia right now. It was a very troubled weekend, roads are blocked to Bahir Dar, no social media, no Viber. Thankfully, my Verizon 3G coverage still works. I talked to Zoë this morning; she loves Africa and her work there so much. She wondered how much news was getting through to the U.S. She is in Amhara where many of the protests boiled over. There's more here. Thanks for keeping Zoë in your thoughts. . .

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    1. Yeah, I was following the news this weekend. We went through this sort of thing when our niece was in Cairo during the coup there a few years ago. We and her parents ended up suffering a lot more than she did, of course. You have my sympathy.

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    2. Thanks, jan. Your perspective is helpful. Zoë actually sounded quite positive except she cannot get to Bahir Dar to get mail, see friends, or to attend workshops. She is persevering in her teaching and mosquito prevention work. Many good life lessons. . .

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    3. Update: Zoë is being evacuated to somewhere safer as I write. I do not know where yet.

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    4. Yes, thanks, jan. Much relief here.

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    5. When my niece was evacuated from Cairo by a Lufthansa charter, she took it as an opportunity to spend a few days touring Berlin before coming home, as I recall.

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    6. That sounds like a great opportunity. I think Zoë may be moving elsewhere within the country but it's unclear as yet. Just glad she is out of the Bahir Dar area.

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  9. New post on "Young Sunflowers Follow the Sun, Mature Sunflowers Face East for the Warmth and Bugs (Florida Anyone?)" is now up.

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