Identification and Preservation of a Rapid Depositional Event: 2010 BP Oil Spill

Following the 2010 DWH Blowout, a depositional pulse was documented in bottom sediments in the NE Gulf of Mexico (GoM). This massive sedimentation event resulted in a ~1 cm thick surface layer deposited within ~5 months, and recorded in bottom sediments as elevated excess ²³⁴Th inventories and mass accumulation rates (MAR) as compared to subsequent sampling periods. The sedimentological signature of the depositional event was recorded differently in two sedimentologic regimes. On the western, siliciclastic sediment-dominated side of the Desoto Canyon, the event was manifested as an increase in calcium carbonate content, and an increase in silt-sized sediments. The eastern, carbonate sediment-dominated side of DeSoto Canyon exhibited no systematic change in carbonate content, but sediments were fining upward through the pulse layer. This sediment distribution pattern is consistent with a massive sediment influx from surface waters in both sedimentological regimes, and is inconsistent with increased siliciclastic sediment input by the Mississippi River. Time series data exhibits reproducibility in the years following initial sampling, and indicates that the sedimentological signature of the event has thus far been preserved. Continuation of the time series will provide insight into the preservation potential of the sedimentological signature of this event, and aid in identification of similar depositional events, whether natural or anthropogenic, that may be preserved in the sedimentary record.