The Chesapeake Bay impact structure is one of the largest and most well preserved impact structures on Earth. It has a unique morphology composed of an inner crater penetrating crystalline basement surrounded by a wider crater in the overlying sediments. In 2004, the U.S. Geological Survey conducted a seismic survey with the goals of constraining crater structure and in support of the drilling of a borehole into the deepest part of the crater. Travel-time and waveform inversion were applied to the data to produce a high-resolution velocity model of the crater. Low-fold reflection processing was also applied. Northeast of the crystalline crater, undeformed, eastward-sloping crystalline basement is ~1.5 km deep. The edge of the inner crater is at ~ 15 km radius and slopes gradually down to a depth of 1.5 - 1.8 km. A central peak of 4-5 km radius rises to a depth of ~0.8 km. Basement velocity in the crystalline crater is much lower than undeformed basement, which suggests ~10% fracturing of the crater floor, and up to 20% fracturing of the central uplift. A basement uplift and lateral change of velocity, interpreted as the edge of the transient crater, occurs at a radius of ~ 11 km. Assuming a 22 km diameter transient crater, scaling laws predict a ~30 km diameter crater and central peak diameter of 8-10 km. This indicates that post-impact collapse processes that created the ~ 30 km diameter crystalline crater were unaffected by the much weaker rheology of the overlying sediments. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/35090 |
| Date | 31 October 2006 |
| Creators | Lester, W. Ryan |
| Contributors | Geosciences, Hole, John A., Imhof, Matthias G., Burbey, Thomas J. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | Thesis.pdf |
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