Tectonic significance of the cold seepage zones in the eastern Nankai accretionary wedge – an outcome of the 15 years’ KAIKO projects
Tectonic significance of the cold seepage zones in the eastern Nankai accretionary wedge – an outcome of the 15 years’ KAIKO projects
复制标题
南海增生楔东部冷渗带的构造意义——15年KAIKO项目的成果
DOI：
10.1016/s0025-3227(02)00242-6
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发表时间：
2002
期刊：
影响因子：
2.9
通讯作者：
Kazuo Kobayashi
中科院分区：
文献类型：
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作者：
Kazuo Kobayashi
根据1984年以来在法日合作项目(Kaiko I、II、Kaiko-South和Kaiko-Tokai)下进行的精确填图和潜水观测结果，结合对日本海沟、相模湾等地区的研究，阐明了南海东部增生楔中冷流体喷发的构造意义。与温度异常有关的底栖生物群落边界非常尖锐，表明营养丰富的流体通过碳酸盐结壳的裂缝集中向上流动，这些裂缝存在于可渗透沉积物的近地表。喷发带的线性排列是浅层拆离断层的表面表现。沿着断层从管道中排出的富含甲烷的流体在上覆的可渗透沉积物中迁移，并与含有硫酸盐的循环海水反应，产生硫化氢和碳酸盐沉淀。碳酸盐岩地壳在构造剪应力作用下发育梯形或之字形裂缝。结论是，双壳类群落生长在碳酸盐裂隙上方的一层薄薄的沉积物上，含有被海水稀释的硫化氢的流体通过碳酸盐裂隙流出。另一方面，细菌垫似乎要么在断层管道上的薄沉积物上生长，要么在没有碳酸盐结壳的厚厚的沉积物上生长。在前一种情况下，双壳类无法生长，因为排放液中含有太多甲烷和硫化氢，无法维持底层水的富氧状态。在南海海槽西部，细粒、渗透性较差的沉积物盖层似乎阻止了流体的循环，而甲烷似乎普遍存在于那里的更深的沉积层中。不同地点渗流方式的主要差异被认为是：(1)导致向上流体喷发通道的构造体制；(2)受海水混合速度影响的喷发流体的速率和组成；以及(3)近底沉积物的渗透率和厚度。
The tectonic significance of the cold fluid venting in the eastern Nankai accretionary wedge has been elucidated based upon results of precise mapping and submersible observation executed since 1984 under the French–Japanese cooperative projects (KAIKO I, II, KAIKO-Nankai and KAIKO-Tokai) in conjunction with studies of the Japan Trench, Sagami Bay and other regions. The very sharp boundary of benthic communities associated with temperature anomalies indicates the occurrence of focused upflow of nutrient-rich fluids through cracks in the carbonate crust existing on a near-surface horizon of permeable sediment. The linear alignment of venting zones is a surface expression of the shallow detachment faults. Methane-rich fluids expelled from the conduit along a fault migrate in the overlying permeable sediment and react with circulating sea water containing sulfate to produce hydrogen sulfide and carbonate precipitate. En echelon or zigzag patterns of the cracks are developed in the carbonate crust under the influence of tectonic shear stress. It has been concluded that bivalve communities grow on a thin veneer of sediment above the cracks of carbonate through which fluid containing hydrogen sulfide diluted with sea water flows out. On the other hand, bacterial mats seem to flourish either on thin sediment overlying the fault conduit or over a thick cover of sediment without carbonate crust. In the former case, bivalves cannot grow because venting fluids are too dense with methane and hydrogen sulfide to maintain the oxygen-rich condition of the bottom water. In the western Nankai Trough fine-grained less permeable sediment cover seems to prevent circulation of fluids, whereas methane appears to be widespread in the deeper sedimentary layer there. Major distinctions in modes of seepage among sites are presumed to be caused by: (1) the tectonic regime causing channels of upward fluid venting; (2) rates and composition of venting fluids affected by mixing rates of sea water; and (3) the permeability and thickness of the near-bottom sediment.
多道地震剖面推断南开海槽东部周边断裂配置
DOI：
--
发表时间：
2002
期刊：
Marine Geology 187
影响因子：
--
作者：
N.Takahashi;H.Amano;K.Hirata;H.Kinoshita;S.Lallemant;H.Tokuyama;F.Yamamoto;A.Taira;K.Suyehiro
通讯作者：
K.Suyehiro
密集气枪-OBS地震剖面研究南海海槽东部和泽尼苏海脊深部地壳结构
DOI：
--
发表时间：
2002
期刊：
Marine Geology Vol.187 (1-2)
影响因子：
--
作者：
Ayako Nakanishi;Hajime Shiobara;Ryota Hino;Kimihiro Mochizuki;Toshinori Sato;Junzo Kasahara;Narumi Takahashi;Kiyoshi Suyehiro;Hidekazu Tokuvama;Jiro Segawa;Masanao Shinohara;Hideki Shimahura
通讯作者：
Hideki Shimahura
影响因子：
2.9
作者：
Ashi, J;Tokuyama, H;Taira, A
通讯作者：
Taira, A