Characterization of the Sedimentation Associated With the Deepwater Horizon Blowout: Depositional Pulse, Initial Response, and Stabilization

Authors

Rebekka A. Larson, Eckerd CollegeFollow
Gregg R. Brooks, Eckerd CollegeFollow
Patrick T. Schwing, University of South Florida
Arne R. Diercks, University of Southern MississippiFollow
Charles W. Holmes, Environchron
Jeffrey P. Chanton, Florida State University
Misael Diaz-Asencio, Ensenada Center for Scientific Research and Higher Education
David J. Hollander, University of South Florida

Document Type

Article

Publication Date

6-29-2019

Department

Marine Science

Abstract

The Deepwater Horizon (DWH) blowout led to a depositional pulse in the northeast Gulf of Mexico in the Fall of 2010 associated with an observed Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) event. A time series (2010–2016) of annually collected sediment cores at four sites characterize the sedimentary response to the event, post-event, and stabilization/recovery. The depositional pulse (2010–2011) was characterized by high sedimentation rates with little to no bioturbation and large excursions in % silt. The lack of changes in sediment composition indicate that the same sediment sources dominated during the event, but the rates of sedimentation increased. In the years following the event (2011–2012), sedimentation rates were lower, and bioturbation was absent, and the initial excursions in % silt began to become undetectable in the sedimentary record. Between 2013 and 2016, a spatially and temporally variable return of bioturbation was detected at most sites. Sedimentation rates at all sites remained low, but increases in ²³⁴Th_xs apparent mass accumulation rates indicated a return of bioturbation and potential stabilization and/or recovery of the sedimentary system. The deepest site (~1500 m) did not have any indication of bioturbation as of the 2016 collections, which may reflect a lack of recovery or that bioturbation was never present. In 2012, ²¹⁰Pb_xs age dating began to resolve the depositional pulse suggesting it may be applied to determine changes in the pulse deposit over time, and/or its preservation in the sedimentary record. Factors that may influence preservation include burial, bioturbation, degradation of the pulse signature, and remobilization of pulse sediments.

Publication Title

Deep Oil Spills

First Page

235

Last Page

252

Recommended Citation

Larson, R. A., Brooks, G. R., Schwing, P. T., Diercks, A. R., Holmes, C. W., Chanton, J. P., Diaz-Asencio, M., Hollander, D. J. (2019). Characterization of the Sedimentation Associated With the Deepwater Horizon Blowout: Depositional Pulse, Initial Response, and Stabilization. Deep Oil Spills, 235-252.
Available at: https://aquila.usm.edu/fac_pubs/16419