HR: 1330h
AN: OS52B-0920    [PDF]
TI: Sedimentation Patterns, Forced Folding and Fluid Upflow Above a Buried Basement Ridge: Results From a High Resolution Seismic 3D Survey
AU: * Zuehlsdorff, L
EM: lzuehls@uni-bremen.de
AF: Dept. of Geosciences, Bremen University, P.O.B. 330440, Bremen, 28334 Germany
AU: Spiess, V
EM: vspiess@uni-bremen.de
AF: Dept. of Geosciences, Bremen University, P.O.B. 330440, Bremen, 28334 Germany
AB: During the German R/V Sonne Cruise SO 149 (2000), a high resolution 3D seismic data set was collected at the eastern flank of the Juan de Fuca Ridge off the west coast of North America. On the basis of this data set, a consistent layer model could be developed for the unusual complex stratigraphic pattern at and around a sediment buried basement elevation called First Ridge. This basement ridge acted and acts as an obstruction for incoming turbidites, however, the effect exerted by bathymetry on the flow of turbiditic particle clouds decreased as the adjacent sedimentary basins filled up. Subsequent major turbiditic events affected the whole area including the top of First Ridge. Hydrothermally driven fluid upflow above First Ridge appears to be focused by narrow high porosity zones, which are observed above equally narrow pronounced basement peaks. The higher porosity can be explained by forced folds developing an extensional strain field throughout the sediment column. The forced folds may either be the result of fault movement within the basement or related to fault processes within the sediment cover itself. Yet forced folds and high porosity do not necessarily mean detectable fluid flow. 3D seismic data rather provide information about the development and distribution of a potential plumbing system and thus an understanding of the nature of the flow. One implication is that the contribution of fluids discharging at First Ridge does not balance the in-going and out-coming fluid budget at the eastern flank of the Juan de Fuca Ridge.
DE: 3022 Marine sediments--processes and transport
DE: 3025 Marine seismics (0935)
DE: 8005 Folds and folding
DE: 8045 Role of fluids
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting