Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Deccan traps volcanic output and the Chicxulub impact

  1. Oct 2, 2015 #1

    jim mcnamara

    User Avatar

    Staff: Mentor

    http://www.sciencemag.org/content/350/6256/76

    [

    The concept is that the impact increased the lava flow markedly. So the ecological impact of the impact was extended over a longer period of time by the vast lava outflows for several hundred thousand years.
     
  2. jcsd
  3. Oct 2, 2015 #2

    Bystander

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Chicxulub and the Alvarez's have been "targets" for thirty years. The approximately antipodal location of the Deccan Traps has been especially appealing/attractive as an alternative/coincident driver for the K-T extinction. Such speculations regarding flood basalts (Siberian:Permian::Deccan:K-T) disregard MOR, mid-ocean ridge, annual basalt formation rates, ~ 10 km3/a.
    https://en.wikipedia.org/wiki/Deccan_Traps
     
  4. Oct 2, 2015 #3

    phyzguy

    User Avatar
    Science Advisor

    At one point there was a hypothesis that, because of plate tectonics, at the time of the impact the Deccan traps site was approximately antipodal to the Chicxulub impact. In this hypothesis seismic waves from the impact were focused at the Deccan trap site and were the cause of the outpouring of lava. Does anyone know if this is still a valid hypothesis?
     
  5. Oct 2, 2015 #4

    davenn

    User Avatar
    Science Advisor
    Gold Member

    That appears to be the premise in the paper linked to in the OP.
    Its what I was also taught in my geology classes at univ.


    D
     
  6. Oct 2, 2015 #5

    Bystander

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

  7. Oct 3, 2015 #6

    jim mcnamara

    User Avatar

    Staff: Mentor

    I think what Bystander may be trying to convey, succinctly, I'm expanding:

    The duration or even the fact of a mass extinction gets muddled up after 60 million years. And. It generally gets fuzzier the further back you go in time. How long did it take for the dinosaurs to beome extinct? We can see (from our viewpoint) very clearly that at some point there were lots of fossils from certain clades of animals and plants. More recent fossils: none. So, voila, extinction. No question there. But did it happen in a week? 15000 years? That is the 'error bar' in Bystander's comments. IMO. He can certainly correct my impression.

    If we can narrow down the time frame, can we tie that period of time to some causative agent(s)? That is what this paper is talking about. In this case the Deccan traps were active (do not forget the timing fuzz problem) and at some point close in time near the Chicxalub impact, the activity surged apparently by orders of magnitude. Cause and effect?

    Cute micro-mammoth from Wrangel Island:
    http://factday.com/2012/04/27/the-last-mammoths-died-on-wrangel-island-around-2000-2500-bce/
    See:
    http://www.nature.com/nature/journal/v362/n6418/abs/362337a0.html

    Mammoths are extinct. Mammoths used to be in North America. So when did that happen? Supposed to be during the Pleistocene Megafauna extinction event. Robin Gibbons at Stanford: From: http://web.stanford.edu/group/journ...ntent/uploads/2012/09/Gibbons_NatSci_2004.pdf
    This is another guise of the exact same problem set being discussed here. Multiple causes and time frames. Did humans cause the extinction? Climate? or both?

    Mammoths lived on Wrangel island until about 2000BC. In other words our discrete approach to extinction as an assumption: 'Wham, you're dead',
    may not be the way extinctions work.

    As a side note - it is very interesting that extinct beasties - we associate mammoths as 'long ago animals' - persisted well into the time of written history. Extensive writing existed in Egypt at this time. As did writing in several other places throughout the Middle East, Asia Minor, India, and China. They did not seem to be interested in dwarf mammoths in the Artic, however. Nobody wrote about them. AFAIK. But they were extant during historical times.
     
    Last edited: Oct 3, 2015
  8. Oct 4, 2015 #7

    Baluncore

    User Avatar
    Science Advisor

    The link referenced is to a copy of the article behind a paywall. There is a .pdf available here.
    http://www.media.inaf.it/wp-content/uploads/2015/10/renne151002.pdf

    A while back when I was a Geology student, the Jurassic dolerite in Tasmania, (15000 km3, ~175Ma), was reported to have been injected into the older Permian–Triassic sediments in a geologically instantaneous 24 hour period. That could be explained by an impact event. Whether the impact was then thought to be direct or antipodean to the Tasmania of that time, I am unaware.

    The injection of the dolerite has also been described as taking place over a period of 20 Ma, correlated with the separation of Tasmania from Antarctica as part of the Gondwanaland breakup. The Jurassic dolerite is also found in Antarctica. But that does not help identify the reason for the unusual rise of a dense magma.

    It appears that the details and interpretation reported may be selected to confirm the personal preferences.
    Scientists are People too.
     
  9. Oct 6, 2015 #8

    Baluncore

    User Avatar
    Science Advisor

    The position of hotspots appear to be mutually antipodal.
    http://www.mantleplumes.org/WebDocuments/Antip_hot.pdf
    "One aspect of the hotspot distribution that has received little attention is its antipodal character. Of 45 dprimaryT hotspots found in most hotspot compilations 22 (49%) form antipodal pairs within observed hotspot drift limits (<= 20 mm/yr). In addition, the available ages, or possible age ranges, for both hotspots of an antipodal pair tend to be similar (<= 10 Myr difference) or overlap."
     
  10. Oct 9, 2015 #9
    "...the ecological impact of the impact..." Awkward. "the ecological effect of the impact..." Better.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Deccan traps volcanic output and the Chicxulub impact
  1. Volcanic lightning. (Replies: 7)

Loading...