[meteorite-list] Shocked quartz and other mineral inclusions in Australasian microtektites

From: Paul H. <oxytropidoceras_at_meteoritecentral.com>
Date: Tue, 9 Mar 2010 7:39:25 -0600
Message-ID: <20100309083925.SVC1J.853883.imail_at_eastrmwml36>

Folco, L. N. Perchiazzi, M. D'Orazio, M. L. Frezzotti, B. P.
Glass, and P. Rochette, 2010, Shocked quartz and other mineral
inclusions in Australasian microtektites. Geology, v. 38,
no. 3, p. 211-214.

http://geology.geoscienceworld.org/cgi/content/abstract/38/3/211

Shocked quartz and other mineral inclusions in Australasian
microtektites. March 2010 Geology and GSA Today Highlights

http://www.physorg.com/wire-news/29077449/march-2010-geology-and-gsa-today-highlights.html

?In a study by Folco et al., the application of high-resolution
analytical techniques including syncrothron X-ray diffraction,
field emission scanning electron microscopy, and microraman
spectroscopy led to the discovery of microscopic mineral
inclusions in Australasian microtektites recovered from deep-sea
sediment cores within 2000 km of Indochina. Inclusions consist
of frequent shocked quartz plus a Zr-phase and trace of Fe-oxide
crystallites. The shocked quartz and the Zr-phase are interpreted
as relicts of the target rock. The occurrence of partially melted
quartz relicts and fluidal structures (schlieren) confirms that
microtektites are quenched molten droplets and not condensates
from a hot plume of vaporized crustal rocks. Furthermore, the
internal homogeneity of Australasian microtektites in terms of
abundance of relict mineral inclusions, vesicles, and schlieren
increases with distance from Indochina. This finding strengthens
the current hypothesis that the source crater of the largest and
youngest tektite-strewn field on Earth is located in the Indochina
region, as internal heterogeneity characterizes normal impact
glass found in or near the source crater. This finding also indicates
that the Australasian microtektites with the longest trajectories
experienced the highest temperature-time regimes. Lastly, the
definition of microtektites should include the possible occurrence
of microscopic relict inclusions as an indication of proximity to
the source crater.?

Related papers are:

Glass , B. P., and C. Koeberl, 2006, Australasian microtektites and
associated impact ejecta in the South China Sea and the Middle
Pleistocene supereruption of Toba. Meteoritics & Planetary Science
vol. 41, no. 2, pp. 305?326.

PDF file at:
http://www.univie.ac.at/geochemistry/koeberl/publikation_list/279-Australasian-microtektites-and-Toba-MAPS2006.pdf

 Prasad, M. S., V. P. Mahale and V. N. Kodagali, 2007, New sites of
Australasian microtektites in the central Indian Ocean: Implications for
the location and size of source crater. Journal of Geophysical Research,
(E: Planets), vol.112, E06007, doi:10.1029/2006JE002857.

PDF file at:
http://drs.nio.org/drs/bitstream/2264/635/4/J_Geophys_Res_112_E_E06007.pdf

Extraterrestrial matter in the oceans, lecture by Dr. M. S. Prasad. PDF file at:
http://drs.nio.org/drs/bitstream/2264/738/2/Refresher_Course_Mar_Geol_Geophys_2007_Lecture_Notes_84.pdf

Yours,

Paul H.
Received on Tue 09 Mar 2010 08:39:25 AM PST