SEQUENCE STRATIGRAPHIC ANALYSIS OF CRETACEOUS STRATA IN THE SOUTHERN BALTIMORE CANYON TROUGH: AN INTEGRATION OF GEOLOGICAL AND GEOPHYSICAL DATA

To evaluate the potential for sequestration of supercritical CO₂in strata on the Mid-Atlantic continental margin, we have tied the depositional facies and biostratigraphic assignments reported in 11 wells to ~1500 km of multichannel seismic profiles in the Southern Baltimore Canyon Trough. These data include wells drilled onshore on the Maryland coastal plain in the 1940s and on the outer continental shelf and rise during the 1970s, as well as seismic lines collected by academia, industry, and the USGS. Focusing on the Cretaceous sediments of the coastal plain and continental shelf between the Chincoteague Inlet and the Delaware Bay, we have used the seismic geometries of bedding planes coupled with the lithological data to delineate depositional sequences and predict sedimentary environments across the margin. Packages of sand overlain by fine-grained sediments at least 800 m below the seafloor are the intervals of primary interest. Drill hole data show estuarine sedimentation extended ~120 km seaward of today's shoreline during the Early Cretaceous. Deeper paleo-water depths are found across the basin in the Aptian through Cenomanian, with a shoaling paleo-geographical gradient from South to North, evidenced by shelfal sediments in the Shell 272-1 and 273-1 wells concomitant with nearshore facies found in sites on the Great Stone Dome farther north (see Baldwin et al., this meeting). Hummocky clinoforms, likely Aptian/Albian, are apparent further to the south in seismic data offshore Maryland, grading upwards to parallel to sub-parallel Cenomanian surfaces. The wells indicate a Turonian base level drop that corresponds to a package of sediment characterized by shingled downlapping seismic reflections that prograde across the outer shelf. Although this likely sand-prone interval is faulted due east of the Delaware Bay, the unit is undisturbed to the south. The uppermost Cretaceous and Paleogene sediments are characterized by a slowing sedimentation rate and toplap/truncation in the seismic data. Our observations fit reasonably with previous analyses of global sea-level (Haq et al. 1988, Miller et al. 2005), as well as regional basin analyses (e.g., Poag 1985, Olsson 1988).

This work was supported by DOE DE-FE0026087 (Mid-Atlantic U.S. Offshore Carbon Storage Resource Assessment Project) to Rutgers managed by Battelle.