UNDERGRADUATE RESEARCH ON THE BAYSIDE CORE OF THE CHESAPEAKE BAY IMPACT STRUCTURE, PAST, PRESENT, AND FUTURE STUDIES

Northern Virginia Community College (NVCC) has secured access to the bottommost 14 feet of the USGS Bayside drill core, a section of Neoproterozoic-aged basement rock dated at 625 Ma. The drilling site is located in the annular trough of the Chesapeake Bay Impact Structure, approximately 8 km from the central crater rim.

The USGS has conducted minimal studies on the basement rock of this particular drill core beyond an initial assessment determining that it is a granodiorite, a discovery confirmed by NVCC students’ petrographic analyses of thin section samples. Feldspar minerals display heavy sericitization; original hornblende (?) and biotite display replacement by chlorite; quartz crystals show evidence of strain, which is likely the result of Appalachian orogenic stress. NVCC analyses found no indication of shock metamorphic effects that would directly implicate the impact. NVCC students also attempted to put the Bayside core intrusive body in a wider geologic context, researching possible correlations to similar-aged intrusions in North America and western Africa. Initial research is inconclusive; plans include continuing petrographic analysis through an honors-option Mineralogy course.