[meteorite-list] AVIRIS image of Meteor Crater

From: Bernd Pauli HD <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 09:46:22 2004
Message-ID: <3AF7E4E4.40532462_at_lehrer1.rz.uni-karlsruhe.de>

Hi All,

Matt Morgan schrieb:

> It has been suggested that it could be a cryptovolcanic feature.

Allen wrote:

> Vulcanism? ... Evidence of shocked quartz?

B.J. Kriens, E.M. Shoemaker, K.E. Herkenhoff (1999) Geology of the
upheaval dome
impact structure, southeast Utah (Journal of Geophysical
Resrearch-Planets,
1999, Vol.104, No.E8, pp. 18867-18887):

Evidence is as follows:

1) sedimentary strata in the center of the structure are pervasively
imbricated
by top-toward-the-center thrust faulting and are complexly folded as
well;
2) top-toward-the-center normal faults are found at the perimeter of the
structure;
3) clastic dikes are widespread;
4) the top of the underlying salt horizon is at least 500 m below the
surface at
the center of the dome, and there are no exposures of salt or associated
rocks
of the Paradox Formation in the dome to support the possibility that a
salt
diapir has ascended through it; and
5) planar microstructures in quartz grains, fan-tailed fracture surfaces
(shatter surfaces), and rare shatter cones are present near the center
of the
structure.

KOEBERL C. et al. (1999) A petrographical and geochemical study of
quartzose
nodules, country rocks, and dike rocks from the Upheaval Dome structure,
Utah
(MAPS 34-6, Nov 1999, 861-868):

Based on our field work and the petrographic and geechemical analyses,
we
conclude that there is no evidence to support the suggestion that the
quartzose
nodules found at the Upheaval Dome structure represent impactites.

None of the dike rocks shows any evidence of shock metamorphic
processes.
Instead, they represent sedimentary rocks with only low-strain
deformation.

Iridium analyses of some of the dike rock and lag deposit samples by
gamma-gamma
coincidence spectrometry show values of 4 to 69 ppt, which is well
within the
normal range displayed by crustal rocks. Thus, the evidence of an impact
origin
for Upheaval Dome is still only confined to structural arguments.

> I'm not going to open the can ...

Nor am I because my two gloves do not fit :-)


Best regards,

Bernd
Received on Tue 08 May 2001 08:21:56 AM PDT