Micro-textures of Methane Seep Carbonates from the Northern South China Sea in Correlation with Fluid Flow

Abstract

Abstract:

A small piece of carbonate concretion collected by research vessel “Haiyang 4” from about 3,000 m seafloor of northern South China Sea was analyzed. The piece of carbonates was identified as methane seep carbonate with 17% magnesium calcites andδ¹³C value of -61.403‰ and δ¹⁸O value of 3.560,6‰. The carbonate shows four micro-textures derived by methane degassing, fluid flow and organisms activities. Calcite rings occur commonly along the walls of vesicles. Inner walls of burrow(worm tubes)are also coated by carbonate rims. Bacterial filaments were found in the fractures or conduits of carbonate, which depended on the methane-rich fluid to survive. Fluid conduits and fractures were often filled by coarser sands, which resulted from fluid flow escaping along these conduits.

Key words: methane seep carbonate, micro-texture, fluid, bacterial filament, South China Sea

CLC Number:

SU Xin, CHEN Fang, LU Hong-feng, HUANG Yong-Yang. Micro-textures of Methane Seep Carbonates from the Northern South China Sea in Correlation with Fluid Flow[J]. Geoscience, 2008, 22(3): 376-381.

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