GEOPHYSICAL INVESTIGATIONS OF A DESERT EYE STRUCTURE IN THE WESTERN DESERT, EGYPT

Bedrock structural basins known as “Desert Eyes” are well-known features in the Western Desert, Egypt. In spite of numerous studies, the origin and 3-d distribution of these features are still topics of debate. As part of a NSF-funded project, surface geophysical investigations were conducted during the winter of 2011. This study reports preliminary results of high-resolution magnetic and seismic refraction surveys of the El Kasr structure, a well exposed Desert Eye southwest of Aswan, Egypt. A 24-channel Geode Seismic Refraction system was used to record ground vibrations created by a home-made weight-drop system. Clear arrivals from several layers were identified. The absolute spatial variation in the geomagnetic field is less than a few tens of nT. Slight along strike variations in the induced magnetism are detected as the surveys progress northward, parallel to the strike of the structure. However, there is little evidence in the magnetic data to suggest any significant north-south trending subsurface structures associated with significant contrasts in magnetic susceptibility, as variation in the east-west data is at maximum 15 nT. Forward modeling of the magnetic data as well as seismic refraction interpretation will be provided to constrain the subsurface geometry of the El Kasr Desert Eye structure and its potential relationship to local faults, with the ultimate goal of providing constraints on various models for the formation of the Eyes.