37th DPS Meeting, 4-9 September 2005
Session 17 Dust, Impacts and Earth Atmosphere
Poster, Monday, September 5, 2005, 6:00-7:15pm, Music Recital Room

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[17.03] Mapping Impact Modified Sediments: Subtle Remote-Sensing Signatures of the Dakhleh Oasis Catastrophic Event, Western Desert, Egypt

A.F.C. Haldemann (JPL, Caltech), M.R. Kleindienst (U. Toronto at Mississauga), C.S. Churcher (U. Toronto), J.R. Smith (Washington University in St. Louis), H.P. Schwarcz, K. Markham (McMaster University), G. Osinski (Agence Spatiale Canadienne/Canadian Space Agency)

Over the past decade members of the Dakhleh Oasis Project have studied enigmatic signatures in the Pleistocene geologic record of portions of the Dakhleh oasis and palaeo-oasis. In particular, Ca-Al rich glass (Dakhleh Glass) points to a catastrophic event between c. 100,000 - 200,000 years ago in this well-studied African savannah and freshwater lake, Middle Stone Age environment. The known glass deposits occur at locations separated by tens of kilometers. Here we report on mapping of remote sensing data (visible, infrared and radar) that is being used to guide wider reconnaissance of the Dakhleh Glass deposits. The remote sensing is anchored on the best-studied feature, the Dakhleh Bow Wave Structure (DBWS), where structural elements of a ~ 400 m putative crater are preserved. These structures are highly degraded, and only subtly apparent in the remote sensing data. The Dakhleh Glass (DG), while chemically unique as a natural glass, is nowhere very extensive, and is thus only a minor constituent in each remote sensing pixel; a full mapping of DG and inferences about the initiating catastrophic event will require detailed field work. The subtle remote-sensing signatures of this relatively recent impact(s) into a sedimentary target at Dakhleh, where the erosion rate is estimated at 0.1 mm/yr, underscore the difficulty in accumulating a clear characterization of the range of sedimentary target modifications associated with smaller (100 m - 1 km) terrestrial craters.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.