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Geoscience ›› 2020, Vol. 34 ›› Issue (01): 130-140.DOI: 10.19657/j.geoscience.1000-8527.2019.010

• Marine Geology • Previous Articles     Next Articles

Geochemical Contrast in Sediments from Active and Inactive hydrothermal Fields on the Southwest Indian Ridge

SONG Bei1(), SU Xin1(), LÜ Shihui1, NI Jianyu2, LIAO Shili2, TAO Chunhui2, HU Maokang1, LI Shiyun1, YU Chonghan1   

  1. 1. School of Ocean Sciences, China University of Geosciences, Beijing 100083, China
    2. The Second Institute of Oceanography, State Oceanic Administration, Hangzhou,Zhejiang 310012, China
  • Received:2019-06-20 Revised:2019-09-20 Online:2020-03-05 Published:2020-03-07
  • Contact: SU Xin

Abstract:

The Longqi and Duanqiao areas are two typical active and inactive hydrothermal fields respectively on the ultra-slow spreading Southwest Indian Ridge (SWIR).For studying the geochemical features between these two regions, 59 seafloor sediments are compared with the material compositions, enrichment factors (EFs) and cluster analysis after major and trace elements test. The results reveal that the two regions show similarities in high contents of biogenic (e.g.Ca, Sr and Ba) and surrounding rock elements (e.g.Fe, Mg, Si and Al),and differences in structure, surrounding rock condition and hydrothermal activities, leading to differential geochemical behaviors of their sediments. We found extra ultramafic rock components in the sediments of Longqi area, where sediments are relatively enrich in hydrothermal elements such as Cu, Zn, Fe and Co. The higher contents of biogenic components in the Duanqiao area, where the hydrothermal related elements are characterized by the obvious enrichment of Pb and W, reflect the biological sedimentation playing dominant roles after hydrothermal activities stopped. Furthermore, the R type cluster analysis gives expression to the extra ultramafic components solely in Longqi area and close connections between hydrothermal activities and mafic base rock in Duanqiao area.

Key words: southwest Indian ridge, active and inactive hydrothermal field, sediment, elemental geochemistry

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