Geological controls on the gas hydrate system of Formosa Ridge, South China Sea

Berndt, Christian, Crutchley, Gareth, Klaucke, Ingo, Jegen, Marion, Lebas, Elodie, Muff, Sina, Lieser, Kathrin, Roth, T., Chi, W.-C., Feseker, T., Lin, S., Liu, C.-S., Chen, L. and Hsu, H.-H. (2014) Geological controls on the gas hydrate system of Formosa Ridge, South China Sea OCEANS 2014 - TAIPEI. IEEE, Taipei, pp. 1-4. ISBN 978-1-4799-3645-8 DOI 10.1109/OCEANS-TAIPEI.2014.6964481.

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Formosa Ridge is one of many topographic ridges created by canyon incision into the eastern South China Sea margin. The northwestern termination of the ridge is caused by beheading of the ridge due to a westward shift of the canyon that originally formed to the eastern flank of Formosa Ridge. Below Formosa Ridge a bottom simulating reflector (BSR) exists. Its depth below sea floor coincides with the theoretical base of the gas hydrate stability zone and the reflection has reverse polarity suggesting that it is caused by free gas below gas hydrate accumulations. The BSR is ubiquitous but shows significant variations in depth below sea floor ranging from 150 ms TWT (or approximately 180 m) underneath the incised canyon in the north to up to 500 ms (or approximately 460 m) underneath the crest of Formosa Ridge. Predominantly this depth variation is the result of topography on subsurface temperature, but comparison with the average BSR depth underneath the surrounding canyons suggests that recent canyon incision in the north has perturbed the thermal state of the sediments. Formosa Ridge consists of a northern half that is dominated by refilled older canyons and a southern half that consists mainly of contourite deposits. However, judging by the reflection seismic data this difference in origin seems to have little effect on the distribution of gas hydrate.

Document Type: Book chapter
Keywords: gas hydrate; sedimentary systems; heat flow
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: No
DOI etc.: 10.1109/OCEANS-TAIPEI.2014.6964481
Projects: Future Ocean
Date Deposited: 29 Sep 2015 12:48
Last Modified: 29 May 2017 12:48

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