Research of the source of gas hydrate by geochemical and geophysical way in Santa Monica Basin and Santa Barbara Basin, southern California, USA
Speaker: Kuan-Ting Lin
Abstract
Seafloor mounds and seeps are very common in the offshore southern California, USA. Since these structures are highly related to the gas hydrate resource, and specially these area are famous by the mass production of petroleum. To understand the mechanism and source of the mounds and seeps is essential. The source of the gas hydrate seeps could be analyzed by geochemical identity of the isotope content, such as £_13C from the plumes, relative to the surrounding environment. The sedimentary environment and geological setting could tell the mechanism of the mounds and seeps. Remote-control instruments such as ROV and AUV are used in the study area for collecting data under seawater. Subbottom profiler (SBP) and mini-sparker (small marine seismic instrument) are used for upper sediment research. The Santa Monica Basin was studied by geochemical way. The elemental and isotopic composition of the methane gas from the venting indicates a microbial origin. It suggests the mounds and seeps in this area were formed by expansion associated with the formation and accumulation of gas hydrate in the subsurface. Geophysical surveys were mostly used in the study of the self of Santa Barbara Basin, which clarifies the shelf is a zone of sediment bypass (sediment starved). In contrast, the source of gas hydrate in this area is from an older formation (Miocene Monterey Formation) and is controlled by subsurface structure (fold and fault).
Reference
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Charles K. P., William R. N., William U. III., David W. C., Rendy K., (2008) Association among active seafloor deformation, mound formation, and gas hydrate growth and accumulation within the seafloor of the Santa Monica Basin, offshore California, Marine Geology 250, 258¡V275.