Paleoenvironmental and paleoclimatic change associated with the Toarcian oceanic anoxic event (T-OAE) was evaluated in five successions located in Switzerland. They represent different paleogeographic settings across the Alpine Tethys: the northern shelf (Gipf, Riniken and Rietheim), the Sub-Brianconnais basin (Creux de l'Ours), and the Lombardian basin (Breggia). The multi-proxy approach chosen (whole-rock and clay mineralogy, phosphorus, major and trace elements) shows that local environmental conditions modulated the response to the T-OAE across the Alpine Tethys. On the northern shelf and in the Sub-Brianconnais basin, high kaolinite contents and detrital proxies (detrital index, Ti, Zr, Si) in the T-OAE interval suggest a change towards a warmer and more humid climate coupled with an increase in the chemical weathering rates. In contrast, low kaolinite content in the Lombardian basin is likely related to a more arid climate along the southern Tethys margin and/or to a deeper and more distal setting. Redox-sensitive trace-element (V, Mo, Cu, Ni) enrichments in the T-OAE intervals reveal that dysoxic to anoxic conditions developed on the northern shelf, whereas reducing conditions were less severe in the Sub-Brianconnais basin. In the Lombardian basin well-oxygenated bottom water conditions prevailed. Phosphorus (P) speciation analysis was performed at Riniken and Creux de l'Ours. This is the first report of P speciation data for T-OAE sections, clearly suggesting that high P contents during this time interval are mainly linked to the presence of an authigenic phases and fish remains. The development of oxygen-depleted conditions during the T-OAE seems to have promoted the release of the organic-bound P back into the water column, thereby further sustaining primary productivity in a positive feedback loop. -- Keywords : Toarcian OAE ; Proximal-distal transect ; Mineralogy ; Geochemistry ; Phosphorus ; Climate change.

中文翻译：

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托阿尔世早期海洋缺氧事件：高山特提斯山脉（瑞士）的古环境和古气候变化

在位于瑞士的五个序列中评估了与 Toarcian 海洋缺氧事件 (T-OAE) 相关的古环境和古气候变化。它们代表了高山特提斯山脉不同的古地理环境：北部陆架（Gipf、Riniken 和 Rietheim）、Sub-Brianconnais 盆地（Creux de l'Ours）和伦巴第盆地（Breggia）。选择的多代理方法（全岩和粘土矿物学、磷、主要和微量元素）表明，当地环境条件调节了整个高山特提斯山脉对 T-OAE 的响应。在北部陆架和 Sub-Brianconnais 盆地，高岭石含量和 T-OAE 间隔中的碎屑替代物（碎屑指数、Ti、Zr、Si）表明气候向更温暖和更潮湿的变化以及化学风化率。相比之下，伦巴第盆地的低高岭石含量可能与特提斯山脉南部边缘更干旱的气候和/或更深、更远的环境有关。T-OAE 区间中氧化还原敏感的微量元素（V、Mo、Cu、Ni）富集表明，北部陆架形成了缺氧至缺氧条件，而 Sub-Brianconnais 盆地的还原条件不那么严重。在伦巴第盆地，底部水条件充氧良好。磷 (P) 形态分析在 Riniken 和 Creux de l'Ours 进行。这是 T-OAE 剖面 P 物种形成数据的第一份报告，清楚地​​表明该时间间隔内的高 P 含量主要与自生阶段和鱼类遗骸的存在有关。T-OAE 期间缺氧条件的发展似乎促进了有机结合的 P 释放回水体，从而在正反馈循环中进一步维持初级生产力。- 关键词：Toarcian OAE；近远横断面；矿物学；地球化学；磷；气候变化。