Tectonic Background of Four Hydrothermal Fields Along the Central Indian Ridge
Tectonic Background of Four Hydrothermal Fields Along the Central Indian Ridge
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DOI：
10.1007/978-4-431-54865-2_11
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
K. Okino;Kentaro Nakamura;Hiroshi P. Sato
中科院分区：
文献类型：
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作者：
K. Okino;Kentaro Nakamura;Hiroshi P. Sato
自2000年在中印度洋脊最南端发现凯雷热液区以来，后来只发现了四个活跃的热液喷口区。这四个热液区的流体和相关生态系统的化学成分显示出显着的多样性。重点地球物理制图和岩石取样表明，不同的构造背景限制了每个油田不同的热液活动。南部的两个热液田位于轴向裂谷壁上。位于25°19′S的富氢海雷热液区受玄武岩浆作用和剥离断层作用的制约，在浅地表下挖出超镁铁岩，而在23°52′S的典型洋中脊型埃德蒙热液区没有发现超镁铁暴露的证据。在CIR中部新发现了另外两个热液区。位于19°33′S的Solitaire油田距离新火山带约2.6 km，可能受到板内火山作用的影响。位于18°20′S的Dodo气田位于轴向谷底的中心，玄武岩片熔岩流掩埋了海底。熔岩的形态和邻近的大型离轴海山的存在支持了这一观点，即在这一部分提供了过量的熔体。异常岩浆活动可能是受地幔柱成分或大偏移转换断层北部的部分。在沿着CIR的四个热液区发现的巨大多样性为全球热液系统的构造控制提供了重要的见解。
Since the discovery of the Kairei hydrothermal field at the southernmost end of the Central Indian Ridge (CIR) in 2000, only four active hydrothermal vent fields have subsequently been discovered. These four hydrothermal fields show remarkable diversity in the chemical compositions of fluids and associated ecosystems. Focused geophysical mapping and rock sampling indicate that different tectonic setting constrains the different hydrothermal activity for each field. Two hydrothermal fields in the southern CIR are located on the axial rift-valley wall. The hydrogen-rich Kairei hydrothermal field at 25°19′S is constrained by both basaltic magmatism and detachment faulting that exhume ultramafic rocks on a shallow subsurface, whereas no evidence of ultramafic exposure is recognized in the typical mid-ocean ridge type Edmond hydrothermal field at 23°52′S. Two other hydrothermal fields have been newly discovered in the central CIR. The Solitaire field at 19°33′S is located about 2.6 km away from the neo-volcanic zone and is likely influenced by intra-plate volcanism. The Dodo field at 18°20′S is located at the center of the axial valley floor, where a basaltic sheet-lava flow buries the seafloor. The lava morphology and the existence of an adjacent large off-axis seamount support the idea that excess melt is supplied in this segment. The anomalous magmatism is likely influenced by mantle plume components or by a large-offset transform fault just north of the segment. The large diversity found in the four hydrothermal fields along the CIR provides important insights on the tectonic control of global hydrothermal systems.