Berndt, Christian

Brückmann, Warner

Hensen, Christian

Klaeschen, Dirk

Planert, Lars

English

OceanRep

ADRESSE Universitätsstraße 150 | 44801 Bochum | GermanyANFAHRT U-Bahn: U35 | Auto: A43, Abfahrt (19) Bochum-Querenburg WWW.RUB.DE70. Jahrestagung derDeutschen Geophysikalischen Gesellschaft15. – 18. März 2010Planert, L. (Kiel / IFM-GEOMAR), D. Kläschen (Kiel / IFM-GEOMAR), C. Berndt (Kiel / IFM-GEOMAR), W. Brückmann (Kiel / IFM-GEOMAR), C. Hensen (Kiel / IFM-GEOMAR)Buildup and gas hydrate system of mound structures offshore Costa Rica revealed by 2DMCS seismic dataE-Mail: lplanert@ifm-geomar.deOur analysis of 2D MCS seismic data from the Middle American margin provides an insightinto the buildup and formation mechanisms of mound structures and the effects of fluid ascenton the gas hydrate system observed on the continental slope offshore Costa Rica. Our targets,Mound Culebra and Mounds 11&12, are the sites of IODP drilling proposal 633-Full2, whichaims to enhance the general understanding of complex forearc dewatering processes of the erosi-ve subduction system off Costa Rica. The new seismic profiles were acquired using the 36-gun,four-string linear gun array of R/V Marcus Langseth, and a 240 channel streamer with 3000 mof active length. We investigate the role of the acoustic basement for the fluid ascent and theinteractions between gas hydrate formation and dissociation with the fluid ascent from the deepsources. The selected mound sites are both related to deep-reaching fault systems, corroboratingpreliminary estimates of the source depth of fluids and extruded material. In addition, the newseismic data shows differences in terms of the mounds’ activity and stage of development. Up-ward bending of the bottom simulating reflection (BSR) and the absence of the reflection in thearea of the fluid conduit may indicate a build-up of free gas within the gas hydrate stability zone,probably due to increased fluid flow and associated hydrate dissociation.

Buildup and gas hydrate system of mound structures offshore Costa Rica revealed by 2D MCS seismic data

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