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Did Chicxulub impact trigger largest Deccan eruptions? (free pdf)



Ben Creisler
bcreisler@gmail.com


A new paper in open access:


Mark A. Richards, Walter Alvarez, Stephen Self, Leif Karlstrom, Paul
R. Renne, Michael Manga, Courtney J. Sprain, Jan Smit, Loÿc
Vanderkluysen and Sally A. Gibson (2015)
Triggering of the largest Deccan eruptions by the Chicxulub impact.
Geological Society of America Bulletin (advance online publication)
doi: 10.1130/B31167.1
http://gsabulletin.gsapubs.org/content/early/2015/04/30/B31167.1.abstract
pdf:
http://gsabulletin.gsapubs.org/content/early/2015/04/30/B31167.1.full.pdf+html



New constraints on the timing of the Cretaceous-Paleogene mass
extinction and the Chicxulub impact, together with a particularly
voluminous and apparently brief eruptive pulse toward the end of the
“main-stage” eruptions of the Deccan continental flood basalt province
suggest that these three events may have occurred within less than
about a hundred thousand years of each other. Partial melting induced
by the Chicxulub event does not provide an energetically plausible
explanation for this coincidence, and both geochronologic and
magnetic-polarity data show that Deccan volcanism was under way well
before Chicxulub/Cretaceous-Paleogene time. However, historical data
document that eruptions from existing volcanic systems can be
triggered by earthquakes. Seismic modeling of the ground motion due to
the Chicxulub impact suggests that the impact could have generated
seismic energy densities of order 0.1–1.0 J/m3 throughout the upper
~200 km of Earth’s mantle, sufficient to trigger volcanic eruptions
worldwide based upon comparison with historical examples. Triggering
may have been caused by a transient increase in the effective
permeability of the existing deep magmatic system beneath the Deccan
province, or mantle plume “head.” It is therefore reasonable to
hypothesize that the Chicxulub impact might have triggered the
enormous Poladpur, Ambenali, and Mahabaleshwar (Wai Subgroup) lava
flows, which together may account for >70% of the Deccan Traps
main-stage eruptions. This hypothesis is consistent with independent
stratigraphic, geochronologic, geochemical, and tectonic constraints,
which combine to indicate that at approximately
Chicxulub/Cretaceous-Paleogene time, a huge pulse of mantle
plume–derived magma passed through the crust with little interaction
and erupted to form the most extensive and voluminous lava flows known
on Earth. High-precision radioisotopic dating of the main-phase Deccan
flood basalt formations may be able either to confirm or reject this
hypothesis, which in turn might help to determine whether this
singular outburst within the Deccan Traps (and possibly volcanic
eruptions worldwide) contributed significantly to the
Cretaceous-Paleogene extinction.


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News release:


https://newscenter.berkeley.edu/2015/04/30/did-dinosaur-killing-asteroid-trigger-largest-lava-flows-on-earth/


Video lecture from last year:

https://www.youtube.com/watch?v=LiFF04rOq3Y