Sulfur isotope ratios in co-occurring barite and carbonate from Eocene sediments: A comparison study
Sulfur isotope ratios in co-occurring barite and carbonate from Eocene sediments: A comparison study
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DOI：
10.1016/j.chemgeo.2019.119454
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发表时间：
2020-03
期刊：
影响因子：
3.9
通讯作者：
Kotaro Toyama;A. Paytan;K. Sawada;T. Hasegawa
中科院分区：
文献类型：
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作者：
Kotaro Toyama;A. Paytan;K. Sawada;T. Hasegawa
为了研究块状碳酸盐作为海水硫酸盐硫同位素比值（δ 34 Ssw）记录器的实用性，在赤道太平洋始新世沉积物中共存的远洋重晶石和块状碳酸盐（IODP Exp. 320/321站点U1331至U1333）的硫同位素比值（δ 34 S）进行了分析。两种矿物的δ 34 S在整个始新世表现出平行的波动，碳酸盐伴生硫酸盐（CAS）值比重晶石重约0.8‰。在先前的研究中，使用物种特异性清洁的浮游有孔虫获得的CAS δ 34 S中观察到类似的偏移。两种不同矿物的一致结果表明，如果沉积后碳酸盐重结晶作用很小，则原始δ 34 SSW可以来自于大量的CAS分析。组合数据集显示，在始新世（从53 Ma到36 Ma），δ 34 SSW增加了约5‰，其中大部分变化在700万年内（53 - 46 Ma）。这一变化比以前报告的更为渐进。δ 34 Ssw的变化时间与北冰洋广泛的黄铁矿埋藏相吻合，支持始新世δ 34 Ssw增加5‰是由北冰洋富34 S水流出所致的假说。
In order to investigate the utility of bulk carbonate as a recorder of seawater sulfate sulfur isotope ratios (δ34Ssw), co-existing pelagic barite and bulk carbonate in Eocene sediments from the Equatorial Pacific Ocean (IODP Exp. 320/321 Sites U1331 to U1333) were analyzed for their sulfur isotope ratios (δ34S). The δ34S from both minerals showed parallel fluctuation throughout the Eocene with carbonate associated sulfate (CAS) values about 0.8‰ heavier than those of barite. A similar offset was observed in CAS δ34S obtained using species-specific cleaned planktonic foraminifers in a previous study. The consistent results from two distinct minerals suggest that the original δ34Sswcan be derived from bulk CAS analysis, if post deposition carbonate recrystallization is minimal.The combined data set showed a ~5‰ increase of δ34Sswduring the Eocene (from 53 Ma to 36 Ma) with the majority of the shift within 7 myr between 53 and 46 Ma. This change is more gradual than previously reported. The timing of this δ34Sswshift coincides with extensive pyrite burial in the Arctic Ocean, supporting the hypothesis that the 5‰ increase in Eocene δ34Sswhas been caused by34S-enriched water outflow from the Arctic Ocean.