Reworking of atmospheric sulfur in a Paleoarchean hydrothermal system at Londozi, Barberton Greenstone Belt, Swaziland
Reworking of atmospheric sulfur in a Paleoarchean hydrothermal system at Londozi, Barberton Greenstone Belt, Swaziland
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斯威士兰巴伯顿绿岩带隆多齐古太古代热液系统中大气硫的改造
DOI：
10.1016/j.precamres.2016.05.007
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发表时间：
2016
影响因子：
3.8
通讯作者：
F. Brouwer
中科院分区：
文献类型：
--
作者：
D. Roerdink;P. Mason;M. Whitehouse;F. Brouwer
太古代黄铁矿中硫的次要同位素(Δ33S，Δ36S)的异常分馏被认为反映了缺氧大气中的光化学反应，大多数样品沿着Δ36S/Δ33S和≈−1的参考阵列落在一起。与该阵列的微小偏差记录了微生物硫酸盐还原或大气来源反应的变化。我们认为，斯威士兰巴伯顿绿岩带隆多兹3.52Ga热液重晶石矿床的大气硫具有不同的次要硫同位素比值(Δ36S/Δ33S和≠和−1)，其硫化物Δ33S和Δ36S值产生了额外的变异性。在现场测量中，黄铁矿中四个稳定的硫同位素揭示了Δ36S与Δ33S的关系和Δ36S/Δ33S的趋势(−3.2S±100.4)，这与共存的重晶石中Δ36S和Δ33S的共变明显不同，这反映了周围的古太古代海水。这反对在重晶石沉积时进行生物或热化学硫酸盐还原，并要求在3.52Ga之前在化学上不同的大气中生成硫化物。为了解释δ34S、Δ33S和Δ36S的变化，我们提出了一个模型，该模型结合了水热浸出硫的再加工、与幼态硫的深层混合和与生物硫化物的表面混合。隆多齐热液系统中非生物和生物过程之间的这些相互作用使基于Δ33S和Δ36S与太古宙参考阵列的偏差来解释生物特征变得复杂。
Anomalous fractionation of the minor isotopes of sulfur (Δ33S, Δ36S) in Archean pyrite is thought to reflect photochemical reactions in an anoxic atmosphere, with most samples falling along a reference array with Δ36S/Δ33S ≈ −1. Small deviations from this array record microbial sulfate reduction or changes in atmospheric source reactions. Here, we argue that reworking of atmospheric sulfur with distinct minor sulfur isotope ratios (Δ36S/Δ33S ≠ −1) produced additional variability in sulfide Δ33S and Δ36S-values in a 3.52 Ga hydrothermal barite deposit at Londozi, Barberton Greenstone Belt, Swaziland.In situmeasurement of the four stable sulfur isotopes in pyrite revealed Δ36S–Δ33S relationships and a Δ36S/Δ33S trend (−3.2 ± 0.4), which is significantly different from the co-variation between Δ36S and Δ33S in the co-existing barite that reflects ambient Paleoarchean seawater sulfate. This argues against biological or thermochemical sulfate reduction at the time of barite deposition, and requires incorporation of sulfide generated in a chemically distinct atmosphere before 3.52 Ga. We propose a model that combines reworking of this sulfur by hydrothermal leaching, deep mixing with juvenile sulfur and surface mixing with biogenic sulfide to explain the observed variation in δ34S, Δ33S and Δ36S. These interactions between abiotic and biological processes in the Londozi hydrothermal system complicate the interpretation of biosignatures based on deviations in Δ33S and Δ36S from the Archean reference array.
影响因子：
5
作者：
Claire, Mark W.;Kasting, James F.;Meadows, Victoria S.
通讯作者：
Meadows, Victoria S.
南部非洲克拉通 Kaapvaal 地壳融化形成早期太古宙长英质绿岩火山岩
影响因子：
5.3
作者：
Kröner;Hoffmann;Münker;Hegner;Liu D.
通讯作者：
Liu D.