The stable isotopic composition of sediments in methane fluid flowing area, Haiyang IV, the northern part of South China Sea

Abstract

Abstract: Sediments from the site GC16 of Haiyang IV, the South China Sea show anomalous values of δ¹³C_org, δ¹⁵N and δ¹³C_inorg. The sulfate methane transition zone (SMTZ) is a key biochemical interface in CH₄ fluid flowing area. The values of δ¹³C_org and δ¹⁵N show obviously depleted in STMZ. Comparing with the date above the STMZ, depleted 1.4‰PDB and 0.93‰ respectively within the zone. The data of δ¹³C_inorg also identify the authigenic carbonates as microbially-mediated methane-derived precipitates. The 2 times of vigorous methane-rich fluid expulsion had occurred since the bottom sediments deposition of the core. The depth of methane fluid arriving coincident with the up limited of STMZ.

Key words: stable isotopic composition, SMTZ, AOM, ammonia oxidation

CLC Number:

P736.4

YU Xiao-guo, JIN Xiao-bing, YAO Xu-ying, GONG Jian-ming. The stable isotopic composition of sediments in methane fluid flowing area, Haiyang IV, the northern part of South China Sea[J]. Journal of Marine Sciences, 2013, 31(3): 1-7.

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