HR: 09:30h
AN: GP51A-07    [Abstracts]
TI: Rock magnetic and geochemical process modelling of overpressured sediments from the northwestern Gulf of Mexico (IODP Exp. 308)
AU: * Franke, C
EM: cfranke@uni-bremen.de
AF: Laboratoire des Sciences du Climat et de l'Environnement (LSCE), CEA-CNRS-UVSQ Campus du CNRS Avenue de la Terrasse, Bat. 12, Gif-sur-Yvette Cedex, 91198, France
AU: * Franke, C
EM: cfranke@uni-bremen.de
AF: University of Bremen Department of Geosciences, Klagenfurterstrasse FB5, Bremen, 28159, Germany
AU: Fu, Y
EM: y.fu@jacobs-university.de
AF: Jacobs University Bremen Marine Geophysics School of Engineering and Science, Campus Ring 1, Bremen, 28759, Germany
AU: Riedinger, N
EM: nrieding@mpi-bremen.de
AF: MPI for Marine Microbiology, Celsiusstr. 1, Bremen, 28359, Germany
AU: Gilhooly, W P
EM: williamg@ucr.edu
AF: University of California, Riverside Department of Earth Sciences, 1242 Geology, Riverside, CA 92521-0423, United States
AU: Jiang, S
EM: shyjiang@nju.edu.cn
AF: Nanjing University Department of Earth Sciences, Center for Marine Geochemistry Research, Nanjing, 210093, China
AU: Heslop, D
EM: dheslop@uni-bremen.de
AF: University of Bremen Department of Geosciences, Klagenfurterstrasse FB5, Bremen, 28159, Germany
AU: von Dobeneck, T
EM: dobeneck@uni-bremen.de
AF: University of Bremen Department of Geosciences, Klagenfurterstrasse FB5, Bremen, 28159, Germany
AB: Four late Quaternary sediment series were recovered from the Brazos-Trinity Minibasin IV and the Ursa Region in the northwestern Gulf of Mexico, offshore Texas and Louisiana (USA) to study in detail the sedimentation processes, slope stability, overpressure and fluid flow mechanisms of rapid sedimentation areas on this passive continental slope. Within the framework of this project, it is specifically important to understand the time frame of the studied processes. Due to a very high sedimentation rate under unconformable conditions (several m/kyr) the classical paleomagnetic approaches are not suitable for time constraints here. Magneto-mineralogic studies as well as electron microscopic analyses yield results on the highly complex magnetic assemblage, which includes various Fe-Ti mineral phases such as (titano-) magnetite, hemoilmenite, and hematite next to Fe-sulphides (mainly greigite and pyrite). The rock magnetic records also show a distinct pattern of either iron oxide or iron sulphide dominated sediment sections, thus it is possible to distinguish between the detrital/continental and postdepositional magnetic signal of the sediments. A conceptual model has been developed combining magnetic and geochemical methods. This enables us to identify various successive non-steady state sedimentation events and to understand the prevailing past ad present environmental conditions. Subsequently we develop a novel approach to further interpret this conceptual model and to constrain a detailed stratigraphic and environmental model for these low-permeability sediments by using multi-parameter correlations as well as non-steady state quantitative geochemical modelling. High resolution rock magnetic records are calibrated with geochemical data sets of acid volatile sulphur (AVS) and chromium reducible sulphur (CRS) estimations. Like that we aim to calculate ages for the distinct sediment packages. The model for the tectonically less complicated Brazos-Trinity drill sites will be linked to the overpressured and tectonically complex Ursa drill sites, where conventional dating methods are very limited.
DE: 1540 Rock and mineral magnetism
DE: 3036 Ocean drilling
DE: 3610 Geochemical modeling (1009, 8410)
DE: 4219 Continental shelf and slope processes (3002)
DE: 4851 Oxidation/reduction reactions (0471)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting