BIBLIOS

Tipo
Artigos em Revista

Tipo de Documento
Artigo Completo

Título
Surface sediment composition and distribution of hydrothermal derived elements at the Duanqiao-1 hydrothermal field, Southwest Indian Ridge

Participantes na publicação
Shili Liao (Author)
Chunhui Tao (Author)
Ágata Alveirinho Dias (Author)
CREMINER
IDL
Xin Su (Author)
Zhen Yang (Author)
Jianyu Ni (Author)
Jin Liang (Author)
Weifang Yang (Author)
Jia Liu (Author)
Wei Li (Author)
Chuanwan Dong (Author)

Resumo
The study of the hydrothermal component in oceanic sediments provides key data for locating active and inactive hydrothermal systems. In this work, we report the geochemistry of surface sediments collected in the newly discovered basaltic-hosted Duanqiao-1 hydrothermal field (DHF) on the Southwest Indian Ridge (SWIR). The sediments are mainly composed of a pelagic fraction (carbonate ooze) with minor clay contents, basaltic debris, FeMn oxyhydroxides, and hydrothermal components. Hydrothermal elements in the DHF exhibit a precipitation sequence of Cu?≈?Co?>?Zn?≈?Pb?>?Fe?>?Mn?≈?Ni?≈?As. Proximal sediments to the hydrothermal discharge area are characterized by high Cu, Pb, Zn, and Co concentrations and higher Cu/Fe and Zn/Fe ratios, decreasing abruptly within the first kilometer. After this proximal area, an evident increase of Mn concentrations and Mn/Fe ratios was observed, denoting higher oxidizing conditions of the hydrothermal plume. Hydrothermal derived Pb and Co precipitated together with the sulfide phases, whereas at the distal sediments Pb, Co, Ni, and As seem to be scavenged from seawater by oxyhydroxides. This was corroborated by increased REE/Fe ratios with distance to the discharge zone. The geochemistry of DHF sediments is consistent with an effective separation of metals during gradual cooling, and concomitant Eh and pH modifications, of the hydrothermal plume when in contact with seawater. This promotes the precipitation of Cu sulfides first, closest to the discharge area, followed by CuZn and Fe sulfides and FeMn oxyhydroxides, in more distal areas. A comparison of the DHF sediments with those from Dragon Horn, another hydrothermal site at the SWIR, suggests that the hydrothermal fluids responsible for mineral precipitation at DHF are less reduced, favoring the formation of sulfides and oxyhydroxides at shorter distances from the discharge zone. These findings are particularly valuable to the understanding of the variation in hydrothermal anomalies detected in sediments from proximal and distal areas of discharge zones, contributing to the development of tools for the discovery of hydrothermal fields.


Suporte
Marine Geology

Identificadores da Publicação
ISSN - 0025-3227

Editora
Elsevier BV



Identificadores do Documento
DOI - https://doi.org/10.1016/j.margeo.2019.105975
URL - http://dx.doi.org/10.1016/j.margeo.2019.105975

Keywords
Geochemistry Sediments Duanqiao-1 hydrothermal field Southwest Indian Ridge

Tags
Southwest Indian Ridge Deep-sea hydrothermal systems

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