High-resolution investigation of event driven sedimentation: Northeastern Gulf of Mexico. (December 2018)

• Record Type: Journal Article
• Authors: Larson, Rebekka A.; Brooks, Gregg R.; Schwing, Patrick T.; Holmes, Charles W.; Carter, Savannah R.; Hollander, David J.
• Is Part Of: Anthropocene. Volume 24(2018)
• Page Start: 40
• Page End: 50
• Publication Date: 2018-12
• Subjects: High-resolution stratigraphy -- Short-lived radioisotopes -- Geochronology -- Event stratigraphy -- Sedimentology -- Gulf of Mexico; Nature -- Effect of human beings on -- Periodicals; Human ecology -- Periodicals; 304.2
• DOI: 10.1016/j.ancene.2018.11.002
• Languages: English
• ISSNs: 2213-3054

Abstract

Graphical abstract: Highlights: Sediment cores (collected 2010–2016) describe sedimentation following the DwH blowout. The depositional pulse consisted of high sedimentation rates and lack of bioturbation. The initial impact consisted of low sedimentation rates and lack of bioturbation. Stabilization consisted of low sedimentation rates and return of bioturbation. High-resolution sampling and analysis allowed for detection of event in sediments. Abstract: A rapid sedimentation pulse in the northeast Gulf of Mexico, associated with the Deepwater Horizon blowout in 2010, provided a unique opportunity to investigate a depositional event in real time and at very high resolution. Sediment cores were collected annually (2010-2016) from four sites and sub-sampled at 2 mm resolution to identify and characterize the sedimentary signature, as well as geochronology and accumulation rates using excess Lead-210 ( 210 Pbxs ) and excess Thorium-234 ( 234 Thxs ). The "time-series" collection of sediment cores on an annual basis allowed for the identification of changes in sedimentation on monthly to annual time-scales, which define the depositional pulse (2010-2011), initial post-event sedimentary impact and response (2011-2012), and post-event stabilization and preservation (2013-2016). The 2010 depositional pulse was short-lived (<1 year) with 234 Thxs inventories and mass accumulation rates (MARs) indicating higher sedimentation rates and an absence of bioturbation as compared to subsequent years. The initial post-event impact/response (2011-2012) exhibited lower 234 Thxs inventories and MARs indicating lower sedimentation rates. The stabilization in sedimentation (2013-2016) was indicated by site-specific apparent increases in MARs that are not supported by increased 234 Thxs inventories, reflecting the re-establishment of bioturbation. Initially, 210 Pbxs was unable to detect the sedimentation pulse, but with subsequent sedimentation and burial, it begins to resolve the event after 3-5 years. The ability to resolve the sedimentation pulse and the following short-term response was possible due to the high-resolution sampling and analysis, unconventional methodologies, and utilization of high sedimentation rates.