Distribution of the Bottom-Simulating Reflector in the Offshore Taiwan Collision Zone

The area offshore from southwest Taiwan is where the Taiwan mountainbelt first encroaches on the Chinese continental margin.The northwestwardconvergence of the Luzon Arc towards the Chinese continentalmargin has resulted in stacking of thick sediments in terms of folds andthrusts off southwest Taiwan.Mud diapirs and bottom simulating reflectors(BSRs)are commonly observed in this region.During the field experiment,the heat probe developed by the Instituteof Oceanography,National Taiwan University is found to be efficient anddurable.Using the newly designed heat probe,we have conducted fourteenin situ heat flow measurements off southwest Taiwan.The results showthat:(1)Temperatures,temperature gradients,and thermal conductivitiesare anomalous and heat flows are higher above the area where muddiapirs appear.The mud diapirs are apparently influenced by relevant deepfluid migration through the pore spaces.The low heat flow found on theflank of a diapir probably results from the low thermal conductivity ofmud breccia containing gas.(2)To apply the gas hydrate temperature-pressurephase diagram to derive temperature gradients from BSRs,if we speculatea gas composition of 90 percent methane and 10 percent ethane in purewater,a close estimation of the temperature gradient(only 6.3 percent less),compared with that measured in situ,is obtained.

並列關鍵字

Methane Hydrates ； Bottom-Simulating Reflectors ； Convergent Boundary ； Multi-Channel Seismic Reflection Data

國際替代計量

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