[meteorite-list] Volcano... Or Giant Impact?

From: Paul H. <oxytropidoceras_at_meteoritecentral.com>
Date: Sun, 23 Oct 2011 20:25:46 -0500
Message-ID: <20111023212546.NK3WP.2148773.imail_at_eastrmwml42>

In [meteorite-list] Volcano... Or Giant Impact? at
http://six.pairlist.net/pipermail/meteorite-list/2011-October/080522.html
Michael Fowler asked:

"My guess is that the impact was at an oblique angle,
since we have many other impact structures without
such pyroclastic like flows.

Anyone know where the impact crater (if preserved)
is in relationship to the flow deposits?"

The crater is hypothesized to lie under the Minch, which is a
strait that separates the Isle of Lewis in the Outer Hebrides
from the north-west Highlands of Scotland. If this is the case,
then it lies at the bottom of the Minch Basin and buried beneath
Precambrian Torridonian strata and a thickness of Permo-Triassic
and Liassic sediments that fill this basin.

The paper is;

Amor, K., S. P. Hesselbo, D. Porcelli, S. Thackrey, and J.
Parnell, 2008, A Precambrian proximal ejecta blanket
from Scotland. Geology. vol. 36, no. 4, pp. 303-306.
http://geology.gsapubs.org/content/36/4/303.short
http://geology.geoscienceworld.org/cgi/content/abstract/36/4/303

A related paper is:

Related paper, in which, the ejecta blanket is interpreted
as volcanic rocks is:

Young, G. M., 2002, Stratigraphy and geochemistry of
volcanic mass flows in the Stac Fada Member of the
Stoer Group, Torridonian, NW Scotland. Royal Society
of Edinburgh Transactions: Earth Sciences. vol. 93,
no. 1, pp. 1-16.

Web pages

The Minch
http://en.wikipedia.org/wiki/Minch

Stac Fada Member
http://web2.ges.gla.ac.uk/~mlee/stac_fada/stac_fada.html

Biggest UK space impact found by Paul Rincon
BBC News, March 26, 2008
http://news.bbc.co.uk/2/hi/science/nature/7314329.stm

A PhD. dissertation about possible impact ejecta deposits is:

Aden, D. J., 2011, An Anomalous Breccia in the
Mesoproterozoic (~1.1 Ga) Atar Group, Mauritania:
Endogenic vs. Exogenic Genesis. Unpublished PhD.
dissertation, Ohio University, Athens, Ohio.
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1276614508
http://etd.ohiolink.edu/view.cgi/Aden%20Douglas%20J.pdf?ohiou1276614508

PDF file at:
http://etd.ohiolink.edu/send-pdf.cgi/Aden%20Douglas%20J.pdf?ohiou1276614508

Another interesting paper is:

Reimold, W. U., V. von Brunn, and C. Koeberl, 1997, Are
Diamictites Impact Ejecta??No Supporting Evidence from
South African Dwyka Group Diamictite. The Journal of
Geology. vol. 105, pp. 517?530.

PDF file at:
http://www.univie.ac.at/...list/128-diamictites-not-impact-J-Geol1997.pdf

Best wishes,

Paul H.
Received on Sun 23 Oct 2011 09:25:46 PM PDT