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LPI Seminar Series

Effective January 1, 2011, LPI seminars will be held on Fridays.

LPI seminars are held from 3:30–4:30 p.m. in the Lecture Hall at USRA, 3600 Bay Area Boulevard, Houston, Texas. Refreshments are served at 4:30 p.m. For more information, please contact Nicolas LeCorvec (phone: 281-486-2118; e-mail: lecorvec@lpi.usra.edu) or Paul Byrne (phone: 281-486-2140; e-mail: byrne@lpi.usra.edu). A map of the Clear Lake area is available here. This schedule is subject to revision.

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See also the Rice University Department of Physics and Astronomy Colloquia and the Department of Earth Science Colloquia pages for other space science talks in the Houston area.

August 2015

Tuesday, August 18, 2015 - Lecture Hall, 3:30 PM

Barbara Tewksbury, Hamilton College
Polygonal Patterns and Desert Eyes: Discovery and Study of Pervasively Developed Bedrock Structures in the Western Desert of Egypt Using Freely Available High Resolution Satellite Imagery
Using high resolution satellite imagery, the NSF-funded Desert Eyes Project has discovered and studied bedrock structures that are pervasively developed over literally tens of thousands of square kilometers in the Western Desert of Egypt. That the vast majority of these structures have gone unrecognized before now is a function of 1) the remoteness and lack of topographic relief in large tracts of the Western Desert, 2) the scale and nature of the structures, and 3) the fact that the structures occur on the "Stable Platform" of Egypt, where previous workers have for the most part not gone looking for interesting bedrock structures. The fold structures are big enough in overall size (a few hundred meters across) and have such shallow dips that they are almost impossible to see from ground level given the lack of topographic relief. But, at the same time, the structures are small enough that they remained essentially "hidden" even at the highest resolution of previously available free imagery (e.g., Landsat panchromatic imagery, 15 m/pixel). With the advent of very high resolution imagery in Google Earth (1-2 m/pixel), these structures are suddenly not only spectacularly visible, but micro-topographic features are clear enough to allow significant structural analysis. Over the past five years, the Desert Eyes Project has discovered and documented the first extensive exposure to have been recognized on land of a unique class of faults known as polygonal faults (Tewksbury et al., 2014). Polygonal faults have previously been studied essentially only in marine basins using seismic data. The Project discovered and is investigating a network of hundreds of long, narrow synclines that produce a strong regional patterning in high resolution satellite images over an area of >20,000 km2 in the Western Desert and also in places east of the Nile. The syncline network developed in a narrow time window between Early Eocene deposition of the limestone’s and formation of cross-cutting faults associated with Red Sea rifting. We are currently mapping these structures over a large area in high resolution satellite imagery and have just acquired industry seismic reflection data to pair with our structural mapping. These structures do not have geometries typical of tectonic fold and fault terrains, and we are testing a variety of non-tectonic models for formation of these structures. ------- Desert Eyes is a joint US-Egypt Project funded by an NSF program designed for international collaboration and led out of the Department of Geosciences at Hamilton College in Clinton, NY..


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