HR: 0800h
AN: OS21A-1513    [Abstracts]
TI: Overview of the evolution of clay mineralogy in the Gulf of Mexico: implications for regional climate and drainage history of the Mississippi and Brazos-Trinity Rivers
AU: Adatte, T
EM: thierry.adatte@unine.ch
AF: Dept. of Earth Sciences, University of Neuchatel, Rue Emile Argand 11, Neuchatel, 2000 Switzerland
AU: * John, C M
EM: cjohn@pmc.ucsc.edu
AF: Dept. of Earth Sciences, University of California, 1156 High Street, Santa Cruz, CA 95060 United States
AU: Flemings, P B
EM: flemings@geosc.psu.edu
AF: Dept. of Geosciences, Penn State University, 307 Deike Building, University Park, PA 16802 United States
AU: Behrmann, J
EM: jan.behrmann@geologie.uni-freiburg.de
AF: 4Geologisches Institut, Albert-Ludwigs-Universitat Freiburg, Albertstr. 23-B, Freiburg, 79104 Germany
AB: In this paper we present the overview and preliminary results of the analysis of clay minerals in two mini basins drilled during IODP Expedition 308. The goal of our project is to explore the vertical and temporal trends in clay mineralogy in the Ursa Basin and the Brazos-Trinity basin #4. The Brazos-Trinity basin was the sink for sands and clays carried by the Brazos and Trinity Rivers, while the Ursa basin was the sink for sediments carried by the Mississippi river. Reconstructing clay minerals (phyllosilicates <2μm in size) accumulations at these locations could thus potentially yield information on changes in the transport and the source of the siliclastic material transported in the course of the Pleistocene by these three rivers. Moreover, because the type of clay formed in soils through weathering processes largely depend on temperature and amount of precipitation, the dataset generated could provide clues on past climate changes. Some of the mechanisms that are hypothesized to play a major role in controlling clay accumulation in the basins investigated are reworking of clays on the American continent (controlled at the time-scale investigated here by changes in precipitation) and turbidity current deposition (controlled mainly by sea-level changes and thus glacio-eustasy). Finally, a major focusing point of Expedition 308 was sediment physical properties in an overpressured basin. Because each clay mineral specie has a specific average grain sizes, physical properties and cation exchange capacity, the clay mineral composition of the sediment investigated here (dominated by clay-sized particles) may partly control how these sediments react to changes in pressure and temperature. Thus, clay mineral data could contribute to our understanding of the physical properties of the sediments in overpressured basins, and collaborations with geotechnical scientist are planned.
DE: 0744 Rivers (0483, 1856)
DE: 0790 Weathering (1625, 1886)
DE: 1861 Sedimentation (4863)
DE: 1862 Sediment transport (4558)
DE: 3002 Continental shelf and slope processes (4219)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005