Major sulfur cycle perturbations in the Panthalassic Ocean across the Pliensbachian-Toarcian boundary and the Toarcian Oceanic Anoxic Event
Major sulfur cycle perturbations in the Panthalassic Ocean across the Pliensbachian-Toarcian boundary and the Toarcian Oceanic Anoxic Event
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DOI：
10.1016/j.gloplacha.2022.103884
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发表时间：
2022-07
影响因子：
3.9
通讯作者：
Wenhan Chen;D. Kemp;R. Newton;Tianchen He;Chunju Huang;Tenichi Cho;K. Izumi
中科院分区：
文献类型：
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作者：
Wenhan Chen;D. Kemp;R. Newton;Tianchen He;Chunju Huang;Tenichi Cho;K. Izumi
早白垩世海洋缺氧事件（T-OAE, ~183 Ma）以海洋缺氧和富有机质沉积物埋藏为主要特征。然而，目前对T-OAE期间海洋缺氧的程度及其对硫循环的影响知之甚少。本文分析了沉积在泛海洋深浅层的Sakahogi剖面和Sakuraguchi-dani剖面的Pliensbachian-Toarcian边界（Pl-To）和T-OAE中还原金属结合硫（δ34Spyrite）和黄铁矿硫浓度（SPY）的稳定硫同位素。结果表明，在Sakahogi的plto - to和T-OAE中，> - 10‰的正偏移与SPY的增加一致；在Sakuraguchi-dani的T-OAE开始时，> - 20‰的正偏移。虽然深水缺氧/缺氧条件的发展可能导致黄铁矿的埋藏增强，并在一定程度上促进了δ 34spyritat Sakahogi的正偏移，但δ 34spyritat Sakahogi的变化很可能受到出口产量和/或保存的增加的控制。在浅陆架上，黄铁矿普遍偏低且变化较大，δ 34spyite的正偏移可能主要归因于沉积速率的升高，氧化还原对黄铁矿丰度的控制作用较小。我们在Sakahogi发现的正δ 34spyrite偏移表明，深水硫循环受到了迄今为止未被认识到的扰动，这可能与此时海底有机质通量增加和黄铁矿埋藏有关，与短暂的缺氧间隔一致。
The early Toarcian Oceanic Anoxic Event (T-OAE, ~183 Ma) was characterized by marine deoxygenation and the burial of organic-rich sediments at numerous localities worldwide. However, the extent of marine anoxia and its impact on the sulfur cycle during the T-OAE is currently poorly understood. Here, stable sulfur isotopes of reduced metal-bound sulfur (δ34Spyrite) and pyrite sulfur concentrations (SPY) have been analyzed across the Pliensbachian-Toarcian boundary (Pl-To) and the T-OAE from the Sakahogi and Sakuraguchi-dani sections (Japan), which were deposited in the deep and shallow Panthalassic Ocean, respectively. Our data reveal marked positive δ34Spyriteexcursions of >10‰ across both the Pl-To and the T-OAE at Sakahogi, coincident with increases in SPY, and a positive excursion of >20‰ at the onset of the T-OAE at Sakuraguchi-dani. Whilst the development of deep-water anoxic/euxinic conditions could have resulted in an enhanced burial of pyrite, and also partly contributed to the positive excursion of δ34Spyrite, variations in δ34Spyriteat Sakahogi were most likely controlled by elevated export production and/or preservation. On the shallow shelf generally low and highly variable SPYand the positive shift in δ34Spyritewere likely attributable mainly to elevated sedimentation rates, with redox playing only a minor role in controlling pyrite abundance. Our discovery of a positive δ34Spyriteexcursion across the Pl-To at Sakahogi indicates a hitherto unrecognized perturbation to the deep-water sulfur cycle, potentially associated with increased seafloor organic matter flux and pyrite burial at this time, consistent with a transient interval of anoxia.