Terrestrial organic matter controlling gas hydrate fori-nation in the Nankai Trough accretionary prism, offshore Shikoku, Japan

被引:16
|
作者
Saito, Hiroyuki [1 ]
Suzuki, Noriyuki [1 ]
机构
[1] Hokkaido Univ, Fac Sci, Dept Nat Hist Sci, Kita Ku, Sapporo, Hokkaido 0600810, Japan
基金
美国国家科学基金会;
关键词
gas hydrate; type of organic matter; CO2; biogenic methane; early diagenesis; Nankai Trough;
D O I
10.1016/j.gexplo.2007.05.007
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Sediment core samples from Sites 1175, 1176, and 1178, ODP Leg 190, Nankai Trough were analyzed for sedimentary organic matter and inorganic elemental compositions to clarify geochemical conditions for the formation of gas hydrate. Low chloride concentrations and anomalously low core temperature infer the existence of gas hydrate at Site 1178. Trace amounts of gas hydrate are also suggested for Site 1176. Site 1175 does not have any significant evidence of gas hydrate, although all the three sites are within the gas hydrate stability zone. The sediment from Site 1178 is characterized by abundant terrigenous organic matter, older geologic ages, and comparatively higher maturity levels, suggesting high rates Of CO2 generation during diagenesis. The CO2 generation potential of sediment may be one of the crucial conditions for the formation of gas hydrate. (C) 2007 Elsevier B.V. All rights reserved.
引用
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页码:88 / 100
页数:13
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