THE CHESAPEAKE BAY IMPACT STRUCTURE: MAPPING MICROBIAL BIOGEOGRAPHIC DISTRIBUTION PATTERNS IN THE DEEP SUBSURFACE AND THE IMPLICATIONS FOR DISCOVERING BIOSIGNATURES

The Chesapeake Bay Impact Structure (CBIS) was created approximately 35 million years ago by a 2-3 km asteroid or comet impacting the shallow continental shelf and was centered near what is now Cape Charles, Virginia. Identifying the presence and dispersal potential of deep subsurface microbiota poses a significant challenge which properly requires assessing spatial and temporal data to be overlaid in distinct datasets covering biologic, geochemical, and hydrologic features identified within the framework of a stratigraphic column. Piecing together datasets from various columns throughout the impact structure then allows for visualizing the distribution of microbiota throughout the structure.

Allopatric speciation is known to be a predominant mechanism to eukaryotic divergence but is it a significant mechanism for microbiological survival in the deep subsurface? In order to understand how life may have evolved and the “signatures” produced, constraints on speciation within the CBIS Eyreville core are being studied to determine if patterns emerge and how they relate to the spatial and temporal datasets in a highly unique environment. The ecology of an impacted subsurface with minimal water presents challenges to survival and yet the microbiota persist even thousands of feet into the subsurface. Studies indicate significant bacterial populations concentrated in impact breccias and suevite but vast regions of nearly pure quartz sand were nearly barren. This supports that heat and salinity are not predominant factors in precluding deep subsurface habitation nor niche exploitation even in areas of scant porosity. Determining the ecological and biogeographical trends has implications for the extent life persists and adapts on our planet and potentially on Mars by assessing the biologic activity within the deep fractured rock.