Early Jurassic long-term oceanic sulfur-cycle perturbations in the Tibetan Himalaya
Early Jurassic long-term oceanic sulfur-cycle perturbations in the Tibetan Himalaya
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DOI：
10.1016/j.epsl.2021.117261
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发表时间：
2021-11
影响因子：
5.3
通讯作者：
Zhong Han;Xiumian Hu;Tianchen He;R. Newton;H. Jenkyns;R. A. Jamieson;M. Franceschi
中科院分区：
文献类型：
--
作者：
Zhong Han;Xiumian Hu;Tianchen He;R. Newton;H. Jenkyns;R. A. Jamieson;M. Franceschi
摘要早侏罗世是一个重要的碳同位素（δ 13 C）全球扰动期。尽管在这段时间内，δ 13 C记录越来越多，但我们对相关的长期环境和气候变化的了解相对较少。为了解释这些事件，我们在这里提出了新的稳定的硫同位素数据的碳酸盐相关的硫酸盐（δ 34 S CAS）的Sinemurian-Pliensbachian间隔从Wölong剖面位于南半球的古地理。在Sinemurian-Pliensbachian边界附近，δ 34 S CAS的总体正移与δ 13 C的负偏移相一致，表明34 S亏损的黄铁矿埋藏率增加。随之而来的负δ 34 S CAS偏移与上Pliensbachian正δ 13 C偏移一致。δ 34 S CAS位移的初始下降翼表明短暂的δ 34 S贫化硫酸盐输入，但这一趋势很快被逆转为正，可能是由最新的Pliensbachian中持续增强的富32 S黄铁矿埋藏通量造成的。模拟结果表明，最大的海洋硫酸盐浓度可能会下降，在Sinemurian-Toarcian间隔，可能是由于大规模的蒸发沉积在特提斯和原大西洋西部和增强黄铁矿埋藏在一些海洋环境。海水硫酸盐的浓度可能已经足够高，以维持一个均匀的硫同位素海洋在Sinemurian晚期，但其持续下降可能已经启动了一个空间异质性的海洋后，Pliensbachian：海洋地球化学状态，被放大的Toarcian海洋缺氧事件。
Abstract The Early Jurassic is an important interval characterized by several global carbon-isotope (δ 13 C) perturbations. Although the δ 13 C records are becoming better documented during this time interval, we have a relatively poor understanding of the associated long-term environmental and climatic changes. In order to decipher these events, we here present new stable sulfur-isotope data of carbonate-associated sulfate (δ 34 S CAS) for the Sinemurian–Pliensbachian interval from the Wölong section in the Tibetan Himalaya that was located palaeogeographically in the southern hemisphere. An overall positive shift in δ 34 S CAS coincides with the negative δ 13 C excursion around the Sinemurian–Pliensbachian boundary, suggesting an increased 34 S-depleted pyrite burial rate. The ensuing overarching negative δ 34 S CAS shift coincides with the upper Pliensbachian positive δ 13 C excursion. The initial falling limb of the δ 34 S CAS shift suggests a transient δ 34 S-depleted sulfate input, but this trend was soon reversed to become positive, likely caused by a persistently enhanced 32 S-rich pyrite burial flux in the latest Pliensbachian. Modeling results show that maximum oceanic sulfate concentration likely decreased during the Sinemurian–Toarcian interval, probably due to large-scale evaporite deposition in the western Tethys and proto-Atlantic and enhanced pyrite burial in a number of marine settings. The concentration of seawater sulfate could have been high enough to maintain a homogeneous sulfur-isotope ocean in the late Sinemurian, but its persistent decrease may have initiated a spatially heterogeneous ocean after the Pliensbachian: an oceanic geochemical state that was amplified during the Toarcian Oceanic Anoxic Event.