热液循环
地质学
地球化学
地幔柱
羽流
玄武岩
地幔(地质学)
矿化(土壤科学)
岩石圈
古生物学
土壤水分
物理
土壤科学
构造学
热力学
作者
Xia Zhang,Zhilei Sun,Nengyou Wu,Hong Cao,Kun Guo
标识
DOI:10.1016/j.gca.2023.05.012
摘要
Deyin-1 hydrothermal field is located on the Southern Mid-Atlantic Ridge (SMAR) 15°S. The geochemical characteristics of substrate basalts record the incorporation of Saint Helena plume components in the magma source, which implies that the hydrothermal mineralization characteristics in Deyin-1 might be influenced by the mantle plume indirectly. In this study, the pyrite trace element contents and sulfide in situ Pb and He-Ar isotope compositions of a chimney sample from Deyin-1 field are determined systematically in order to clarify the mantle plume influence on local hydrothermal mineralization process. The higher Ba/Co ratios in Deyin-1 pyrites, compared with those from other mid-ocean ridge hydrothermal fields, may be related to the Saint Helena mantle plume influence. Besides, Deyin-1 pyrites possess lower Pb/As, Ag/As, Ni/As ratios and higher As contents than ultramafic-hosted hydrothermal fields, indicating the Deyin-1 is a mafic-hosted hydrothermal system. The higher Se, Co and lower Zn, As, Pb contents in pyrites from interior layers of the chimney demonstrate that the fluid temperature increases during the chimney growth. The in situ Pb isotope compositions of Deyin-1 sulfides are similar to those of mantle plume-influenced basalts in SMAR 15°S and more radiogenic than that of the plume-free SMAR basalt, which demonstrates that the Saint Helena mantle plume has contributed parts of Pb (and other metal elements) to the Deyin-1 sulfides. The He isotope compositions of Deyin-1 sulfides also prove the mantle plume contribution to the hydrothermal system. End-member mixing calculation of Pb-He isotopes indicates that the Saint Helena plume components account for about 3% of the mineralization material sources in Deyin-1 sulfides. Many hydrothermal fields have been discovered near the hot spots besides Deyin-1. Our study emphasizes that mantle plume influence on hydrothermal mineralization might be ubiquitous and needs to be revaluation. This study might shed some light on modern seafloor hydrothermal mineralization process and lithosphere-seawater mass exchange.
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