Low marine sulfate concentrations and the isolation of the European epicontinental sea during the Early Jurassic
Low marine sulfate concentrations and the isolation of the European epicontinental sea during the Early Jurassic
复制标题
早侏罗世期间海洋硫酸盐浓度低和欧洲大陆海的隔离
作者：
Newton R
早侏罗世海水硫酸盐同位素组成的两个记录表明，在欧洲陆表海和开放的特提斯洋之间存在大的同位素梯度。这些差异可以解释为修改开放的海洋硫酸盐同位素组成的水团隔离，海平面上升，不断变化的区域风化和黄铁矿埋藏通量的影响，在一个时间的快速环境变化。这两个记录都含有大的正同位素偏移。在来自欧洲的剖面（英国约克郡）中，6‰的偏移开始于富含有机质的页岩中间的Toarcian早期exaratum亚带，代表了一个著名的海洋缺氧事件。来自西藏的一个开放的特提斯边缘记录记录了一个更大的19‰的漂移，但该剖面的年代不太好。两个年龄的解释是可能的：稀疏的生物地层学证据的地方，这在Aalenian漂移，但我们认为，它可能与积极的漂移在约克郡。因此，这些记录可能同时记录了一个Toarcian事件和一个Aalenian硫同位素事件，或仅记录了早期Toarcian缺氧事件。根据西藏剖面对同位素随时间变化率的保守估计表明，早侏罗世海水硫酸盐浓度在1至5 mM之间，远低于以前的想法。
Two records of seawater sulfate isotope composition from the Early Jurassic demonstrate that large isotopic gradients existed between the European epicontinental sea and the open Tethys Ocean. These differences can be explained by the modification of open-ocean sulfate isotopic compositions by water-mass isolation, sea-level rise, and the effects of changing regional weathering and pyrite burial fluxes, during a time of rapid environmental change. Both records contain large positive isotopic excursions. In the section from Europe (Yorkshire, UK), a 6‰ excursion begins in the early exaratum subzone of the Toarcian in the middle of the organic-rich shale representing a well-known oceanic anoxic event. An open Tethyan margin record from Tibet records a much larger 19‰ excursion, but the section is less well dated. Two age interpretations are possible: sparse biostratigraphic evidence places this excursion in the Aalenian, but we suggest that it may correlate with the positive excursion in Yorkshire. Hence these records may document both a Toarcian event and an Aalenian sulfur isotope event, or the early Toarcian anoxic event alone. Conservative estimates of the rate of isotopic change with time based on the Tibetan section suggest that Early Jurassic seawater sulfate concentrations were between 1 and 5 mM, much lower than previously thought.
侏罗纪的 U-Pb 和 40Ar/39Ar 时标
DOI：
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发表时间：
2000
期刊：
影响因子：
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作者：
J. Pálfy;Paul L. Smith;J. Mortensen
通讯作者：
J. Mortensen
南美大陆的历史与古动物地理研究
DOI：
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发表时间：
1981
期刊：
影响因子：
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作者：
A. Hillebrandt
通讯作者：
A. Hillebrandt
测定三叠纪末和早侏罗世大规模灭绝、相关大型火成岩省和同位素事件
DOI：
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发表时间：
2002
期刊：
影响因子：
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作者：
J. Pálfy;Paul L. Smith;J. Mortensen
通讯作者：
J. Mortensen