Type of Document Thesis Author Ingram, Wesley Clint Author's Email Address email@example.com URN etd-11142005-161228 Title Anatomy of Oligocene-Miocene Debris Flows and Slumps from Demerara Rise: Implications for Margin Destruction Degree Master of Science Department Geological Sciences, Department Advisory Committee
Advisor Name Title Sherwood W. Wise, Jr. Committee Chair Anthony J. Arnold Committee Member Ionel M. Navon Committee Member Philip Froelich Committee Member William Parker Committee Member Keywords
- Calcareous Nannofossils
- Debris Flows
- Demerara Rise
Date of Defense 2005-08-12 Availability unrestricted AbstractABSTRACT
Calcareous nannofossils and stable isotopes were analyzed to determine the timing and causes of extensive Miocene debris flows and Oligocene slumps recovered by Ocean Drilling Program (ODP), cruise Leg 207 to Demerara Rise along French Guiana and Suriname. Five modes of emplacement are considered for the Oligocene and Miocene failures. These hypotheses include canyon incision and infilling, clathrate dissociation, sediment loading, current activity, and seismic triggering.
Calcareous nannofossil ages of the Miocene debris flows at Hole 1261A down to 351 mbsf indicate that the debris flow(s) were emplaced within the time period of Subzone NN11b (7.2 – 5.5 Ma). Hence, nannofossil biostratigraphy provides a time interval of 1.7 m.y.
Compared to previous drilling along the New Jersey Transect these results indicate the mass wasted deposits here are fundamentally different, i.e., not the result of canyon incision and infilling. Instead, this study suggests that the emplacement of the Miocene debris flows resulted from high mass accumulation rates combined with a seismic trigger. Paleocurrent reorganization and/or sea-level changes best account for the Oligocene slumps.
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