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Supernova link to Rancholabrean fauna extinction?



From: Ben Creisler
bh480@scn.org

OK...this is not about dinosaurs, but it may interest people anyway. At
least it might inspire some paleoartists...


G. Robert Brakenridge (2011)
Core-collapse Supernovae and The Younger Dryas/Terminal Rancholabrean
Extinctions.
Icarus (advance online publication)
doi:10.1016/j.icarus.2011.06.043 
http://www.sciencedirect.com/science/article/pii/S0019103511002612

Abstract
Early predictions that some supernovae release large quantities of prompt
high energy photons are now corroborated by optical identification of
core-collapse supernovae associated with extragalactic GRBS (beamed
gamma-ray bursts) and XRFS (beamed or unbeamed x-ray flashes). Given the
in-galaxy supernova frequency and GRB and XRF recurrence statistics,
significant Earth-incident events during the past several million years
very likely occurred and nearby events should have affected the Earth and
other planetary atmospheres, including terrestrial surface solar UV, the
Earth?s climate, and its ecology. The Younger Dryas Stadial (12,900 to
11,550 calendar yr BP) began with sharply cooler temperatures in the
Earth?s northern hemisphere, regional drought, paleoecological evidence
compatible with increased UV, and abrupt increases in cosmogenic 14C and
10Be in ice and marine cores and tree rings. In North America,
stratigraphic and faunal sequences indicate that a major pulse of mammalian
extinctions (at least 23-31 genera) began very close to 12,830 calendar yr
BP and was sudden: deposits one century younger are devoid of diverse
extinct fauna remains. A 10 second beamed GRB within 2 kpc of the Earth
delivers 100 kJ m-2 fluence to the Earth?s atmosphere, where it causes
spallation and catalytic reactions depleting 35-50% O3, and producing
excess NOx species (which favor cooling, drought, and surface fertility),
14C, and 10Be. An un-beamed, 1050 erg hard photon impulse at  250 pc
produces similar terrestrial atmospheric effects. A well-characterized
massive star supernova, the unusually close Vela event (d = 250 ± 30 pc;
total energy of 1-2 x 1051 erg; age constrained from remnant nebula shock
velocities considerations at 13,000-16,000 yr and from the pulsar
characteristic age at 11,400 yr) may have initiated the Younger Dryas
climate change, and caused the extinction of the terminal Rancholabrean
fauna.



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