HR: 1340h
AN: T13B-0454    [Abstracts]
TI: Dewatering Through Mud Mounds on the Continental Fore-arc of Costa Rica
AU: * Fekete, N
EM: nfekete@ifm-geomar.de
AF: SFB 574, C. A. Univ. of Kiel, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: * Fekete, N
EM: nfekete@ifm-geomar.de
AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Grevemeyer, I
T13B-0454 AF: SFB 574, C. A. Univ. of Kiel, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Grevemeyer, I
T13B-0454 AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Reston, T J
T13B-0454 AF: SFB 574, C. A. Univ. of Kiel, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Reston, T J
T13B-0454 AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Spiess, V
T13B-0454 AF: Dept. of Earth Science, Univ. of Bremen, Klagenfurter Str., Bremen, 28359 Germany
AB: Mud mounds occur abundantly on the continental fore-arc of Middle America Trench. Their role in subduction dewatering and contribution to fore-arc material output has been studied extensively throughout the past decade. Based on seismic and thermal investigations, we compare the tectonic, structural and thermal setting of a set of such features of possible diapiric origin at two locations. One is a single mound offshore Northern Costa Rica, located above incoming lithosphere from the East Pacific Rise (EPR), the other is a mound cluster further southeast, where the Fracture Zone Trace separating EPR crust from material produced at the Cocos-Nazca Spreading Center (CNS) subducts. Both target areas exhibit small-scale deformation resulting from subduction erosion and fore-arc subsidence, with variations caused by the topographical contrast of the subducting oceanic plate. This influences dewatering patterns, as does locally elevated sediment deposition near growth faults, or carbonate precipitates on the seafloor. The presence of gas hydrates in the subsurface is marked by the regional appearance of a negative-polarity bottom simulating reflector (BSR) in the seismic data. Using its depth below seafloor as an indicator of thermal changes, they are quantified through heat flow modelling to yield implications of the local thermal state in the vicinity of the mounds. These observations in turn enable us to track dewatering at depth as well as its along-trench variations.
DE: 3060 Subduction zone processes (1031, 3613, 8170, 8413)
DE: 8045 Role of fluids
SC: Tectonophysics [T]
MN: Fall Meeting 2005