A paired sulfate-pyrite δ34S approach to understanding the evolution of the Ediacaran-Cambrian sulfur cycle
A paired sulfate-pyrite δ34S approach to understanding the evolution of the Ediacaran-Cambrian sulfur cycle
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DOI：
10.1016/j.gca.2008.03.021
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发表时间：
2008-06-01
影响因子：
5
通讯作者：
Grotzinger, J. P.
中科院分区：
文献类型：
--
作者：
Fike, D. A.;Grotzinger, J. P.
在全球分布的最新埃迪卡拉-早寒武世地层中，保存着一个异常富集的海相硫酸盐三角洲S-34（SO 4）。这种异常接近埃迪卡拉-寒武纪边界和相关的进化辐射，引起了人们的猜测，认为两者是因果关系。在这里，我们提出了一个高分辨率的记录成对的硫酸盐（三角洲S-34（SO 4），）和黄铁矿（三角洲S-34（pyr））从沉积物跨越约。5.47 - 5.40亿年前（Ma）来自阿曼苏丹国的Huqf超级集团的Ara集团。我们观察到S-34（SO 4）的增量从接近20%。接近42%。从CA开始。550 Ma，至少持续到大约500 Ma。540 Ma。在此期间，S-34（pyr）的含量也随之增加，从大约-15ppm增加到10 ppm。这种全球相关的富集，这里称为阿拉异常，构成了一个重大的扰动硫循环。这里报告的S-34（pyr）的绝对值和世界各地的等效部分，要求进入海洋的物质（S-34（in））的同位素组成比现代（类似于千分之三）的值明显更丰富，在Ediacaran晚期-寒武纪早期可能超过千分之十二。在三角洲S-34（in）升高的背景下，Ara异常不是由硫酸盐和黄铁矿（三角洲S-34）之间的分馏增加来解释的，而是由黄铁矿埋藏（f（pyr））的增加来解释的，最有可能是由有机碳的初级生产和封存增强驱动的，与早期报告的有机碳埋藏升高和广泛的磷块岩沉积一致。(C)2008爱思唯尔有限公司保留所有权利。
An anomalous enrichment in marine sulfate delta S-34(SO4), is preserved in globally-distributed latest Ediacaran-early Cambrian strata. The proximity of this anomaly to the Ediacaran-Cambrian boundary and the associated evolutionary radiation has invited speculation that the two are causally related. Here we present a high-resolution record of paired sulfate (delta S-34(SO4),) and pyrite (delta S-34(pyr)) from sediments spanning ca. 547-540 million years ago (Ma) from the Ara Group of the Huqf Super-group, Sultanate of Oman. We observe an increase in delta S-34(SO4) from similar to 20%. to similar to 42%., beginning at ca. 550 Ma and continuing at least through ca. 540 Ma. There is a concomitant increase in delta S-34(pyr) over this interval from similar to - 15 parts per thousand to 10 parts per thousand. This globally correlative enrichment, here termed the Ara anomaly, constitutes a major perturbation to the sulfur cycle. The absolute values of delta S-34(pyr) reported here and in equivalent sections around the world, require the isotopic composition of material entering the ocean (delta S-34(in)) to be significantly more enriched than modern (similar to 3 parts per thousand) values, likely in excess of 12 parts per thousand during the late Ediacaran-early Cambrian. Against this background of elevated delta S-34(in), the Ara anomaly is explained not by increased fractionation between sulfate and pyrite (Delta delta S-34), but by an increase in pyrite burial (f(pyr)), most likely driven by enhanced primary production and sequestration of organic carbon, consistent with earlier reports of elevated organic carbon burial and widespread phosphorite deposition. (C) 2008 Elsevier Ltd. All rights reserved.