HR: 1340h
AN: OS33A-0569    [Abstracts]
TI: Sedimentological Signatures of Transient Depositional Events in the Cariaco Basin, Venezuela
AU: * Elmore, A C
EM: aelmore@geol.sc.edu
AF: Department of Geological Sciences, University of South Carolina, Columbia, SC 29205
AU: Thunell, R C
EM: thunell@geol.sc.edu
AF: Department of Geological Sciences, University of South Carolina, Columbia, SC 29205
AU: Black, D E
EM: dblack1@uakron.edu
AF: Department of Geology, University of Akron, Akron, OH 44325
AU: Murray, R W
EM: rickm@bu.edu
AF: Department of Earth Science, Boston University, Boston, MA 02215
AU: Martinez, N C
EM: nahysa@bu.edu
AF: Department of Earth Science, Boston University, Boston, MA 02215
AB: The varved sediments that have accumulated in the Cariaco Basin throughout the Holocene provide a detailed archive of the region's climatic history, and act as a historical record for the occurrence of phenomena such as earthquakes and coastal flooding. In this study we compare the sedimentological characteristics of lithogenic material collected from the water column during transient depositional events to those of normal hemipelagic sedimentation in the basin. Specifically, we have examined the clay mineralogy and grain size distribution of detrital material delivered to the basin by the July 9, 1997 earthquake near Cumana, Venezuela and the coastal flooding of Venezuela in late 1999. The sample material used in our study was collected as part of an ongoing sediment trap time series in the Cariaco Basin. The sedimentological signatures associated with these two events are distinctive from the typical lithogenic input to the basin. Preliminary data for biweekly samples collected from 1997-1999 shows a tri-modal particle size distribution, with peaks at 3, 22, and 80 �m. However, material collected from the deep basin immediately following the 1997 earthquake is characterized by a particle diameter distribution at 6 and 22 �m with a smaller than normal peak at 80 �m; this variance suggests an alternate source of material was delivered to the basin via a turbidity flow induced by the earthquake. Supporting this theory, the clay mineralogy of the same sediment trap samples shows a higher than average ratio of kaolinite to quartz for sediments delivered to the basin following both the earthquake and flooding. We hope to extend the use of these sedimentological methods to identify past transient depositional events in Cariaco Basin cores.
DE: 4267 Paleoceanography
DE: 3022 Marine sediments--processes and transport
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting