POSTIMPACT DEFORMATION ASSOCIATED WITH THE LATE EOCENE CHESAPEAKE-BAYIMPACT STRUCTURE IN SOUTHEASTERN VIRGINIA

Upper Cenozoic strata covering the Chesapeake Bay impact structure in southeastern Virginia record intermittent differential movement around its buried rim. Miocene strata in a graben detected by seismic survey s on the York River exhibit variable thickness and are deformed above the crater rim. Fan-like interformational and intraformational angular unconformities within Pliocene-Pleistocene strata, which strike paral lel to the crater rim and dip 2 degrees-3 degrees away from the crater center, indicate that deformation and deposition were synchronous. Co ncentric, large-scale crossbedded, bioclastic sand bodies of Pliocene age within similar to 20 km of the buried crater rim formed on offshor e shoals, presumably as subsiding listric slump blocks rotated near th e crater rim.