Investigation of Lower Crustal and Uppermost Mantle Structure beneath the Illinois Basin Based on Reprocessing of High-Quality Industry Seismic Reflection Profiles

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Investigation of Lower Crustal and Uppermost Mantle Structure beneaththe Illinois Basin Based on Reprocessing of High-Quality IndustrySeismic Reflection ProfilesEAR-0307539John McBrideABSTRACTHigh-quality vibroseis-source seismic reflection profiles from the Illinois Basin, will be reprocessed in order to extend the presently processed record from 4 seconds (~12 km depth) to 20 seconds (~68 km depth) in order to provide information on the structure and origin of the lower crust and uppermost mantle beneath a poorly studied area of the Midcontinent USA. Preliminary test processing of the records confirms that the sub-Moho lithosphere is highly reflective (including correlations between cross lines), which is unusual for deep seismic reflection records from the USA, and thus assures a high probability of providing new images of lower crust and uppermost mantle structure. An ultimate objective will be to furnish geophysical constraints on interpreting the origin of an intra-cratonic basin, like the Illinois Basin. The proven technique of vibroseis extended re-correlation will be used in conjunction with state-of-the-art data processing, including extensive testing of various filtering routines for noise suppression, pre-stack depth and conventional time migration, and 2.5-D visualization and mapping of lower crust and mantle reflectors using Landmark Graphics work-station based processing modules. The fact that unambiguous mantle reflectivity has been virtually unknown from the many thousands of kilometers of deep seismic reflections surveys conducted in the USA means that the present study will add considerably to our knowledge of mantle reflectivity beneath North America. This project will provide one M. S. Geology graduate student with a unique research experience in processing and interpreting high-quality deep seismic reflection data using state-of-the-art technology. In addition, one Earth Science and Space Education undergraduate major will work with and assist the graduate student in formulating a classroom and poster/computer demonstration of deep seismology for secondary (K-12) application.