Lead, Sulfur, and Oxygen Isotope Systematics in Hydrothermal Precipitates from the 14 degrees S Hydrothermal Field, South Mid-Atlantic Ridge
Lead, Sulfur, and Oxygen Isotope Systematics in Hydrothermal Precipitates from the 14 degrees S Hydrothermal Field, South Mid-Atlantic Ridge
复制标题
南大西洋中脊南纬 14 度热液场热液沉淀物中的铅、硫和氧同位素系统学
DOI：
10.1111/rge.12101
复制
发表时间：
2016
期刊：
影响因子：
1.4
通讯作者：
Ye Jun
中科院分区：
文献类型：
--
作者：
Li Bing;Shi Xuefa;Li Chuanshun;Wang Jixin;Pei Yanliang;Ye Jun
在南大西洋中脊（SMAR）和卡德诺断裂带之间的内角，14°S热液区具有丰富的富含二氧化硅的硫化物，被确定为火山碎屑岩，这为研究内角相关的热液矿化提供了第一次机会。对14°S区两个地点（火山顶和斜坡地点）的热液硫化物样品进行了S、Pb和O同位素测定。Pb同位素均一值（207 Pb/204 Pb = 15.466 − 15.472; 206 Pb/204 Pb = 18.242 − 18.252）和δ 34 S值（顶位+6.3 ~+6.85‰;斜坡位置，+2.37至+3.36‰）表明，金属和大部分硫的来源是上地壳，而一些硫来源于向下渗透的海水，特别是在顶部。从石英和海水中计算出的氧同位素平衡温度在顶部站点在94 °C和144°C之间，在斜坡站点在179 ° C和196°C之间。这些同位素替代物与地质背景调查数据一起具有重要意义：这些地点之间的差异可能是由于地壳渗透性的变化，这也影响了向下渗透的海水和向上热液端元流体之间的混合水平，并决定了各种矿化类型。
At the inside corner between the South Mid‐Atlantic Ridge (SMAR) and the Cardno fracture zone, the 14°S hydrothermal field, with its abundant silica‐rich sulfides, was identified as a volcanic massif, which provided the first opportunity to study inside corner‐related hydrothermal mineralization. S, Pb, and O isotopes were measured in hydrothermal sulfide samples from the two sites (volcanic top and slope sites) in the 14°S field. The homogeneous Pb isotope values (207Pb/204Pb = 15.466 − 15.472;206Pb/204Pb = 18.242 − 18.252) and the δ34S values (top site, +6.3 to +6.85‰; slope site, +2.37 to +3.36‰) suggest that the source of metals and most of the sulfur is the upper crust, whereas some sulfur is sourced from downward‐penetrating seawater, especially in the top site. The calculated oxygen isotope equilibration temperatures from quartz and seawater are between 94 and 144°C for the top site and between 179 and 196°C for the slope site. These isotopic proxies, together with geological background survey data, have an important implication: Discrepancies between the sites may result from variations in crust permeability, which also affect the mixing level between downward‐penetrating seawater and upward hydrothermal end‐member fluids and determine the various mineralization types.