On Feb 19, 11:24 am, "David B. Benson" <[EMAIL PROTECTED]> wrote:
> On Feb 18, 6:54 pm, "Steve Bloom" <[EMAIL PROTECTED]> wrote:
>
> > Is it clear that the clathrates remained stable? Reference?
...
>
> Sorry, I haven't kept any of the references. :-(
Hmmm. Maybe
http://geosci.uchicago.edu/~archer/reprints/archer.ms.hydrate_rev.pdf
via
http://scholar.google.com/scholar?q=clathrate+methane+PETM
and there's
http://www.realclimate.org/?comments_popup=398#comment-24993
asking about
"in AGU Geophysical research letters an article about methane hydrates
titled Origin of pingo-like features on the Beaufort Sea shelf and
their possible relationship to decomposing methane gas hydrates, sheds
new information about this menace...."
(question not answered before the thread closed, but it was asked by
Tony Noerpel -- 5 February 2007)
Here's the AGU abstract:
http://www.agu.org/pubs/crossref/2007.../2006GL027977.shtml
Yeah, I recall seeing and likely mentioning this one. The Abstract
says:
-----
The Arctic shelf is currently undergoing dramatic thermal changes
caused by the continued warming associated with Holocene sea level
rise. During this transgression, comparatively warm waters have
flooded over cold permafrost areas of the Arctic Shelf. A thermal
pulse of more than 10°C is still propagating down into the submerged
sediment and may be decomposing gas hydrate as well as permafrost. A
search for gas venting on the Arctic seafloor focused on pingo-like-
features (PLFs) on the Beaufort Sea Shelf because they may be a direct
consequence of gas hydrate decomposition at depth. Vibracores
collected from eight PLFs had systematically elevated methane
concentrations. ROV observations revealed streams of methane-rich gas
bubbles coming from the crests of PLFs. We offer a scenario of how
PLFs may be growing offshore as a result of gas pressure associated
with gas hydrate decomposition.
-----
I recall finding imagery somewhere online taken from someone's ROV,
and seismic imaging of the sediment showing how methane was changing
the layers and creating the "pingo" structures; I have the impression,
though I don't recall any survey proving it, that people thought
they're popping up rapidly in current time, not just leftovers from
the end of the last glaciation.
Hmmmmm ... just quickly poking for info, I haven't done any thing
close to a real search on this.
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