Severe global climate change led to the deterioration of environmental conditions in the oceans during the Toarcian Stage of the Jurassic. Carbonate platforms of the Western Tethys Ocean exposed in Alpine Tethyan mountain ranges today offer insight into this period of environmental upheaval. In addition to informing understanding of climate change in deep time, the effect of ancient carbon cycle perturbations on carbonate platforms has important implications for anthropogenic climate change; the patterns of early Toarcian environmental deterioration are similar to those occurring in modern oceans. This study focuses on the record of the early Toarcian Oceanic Anoxic Event (ca 183.1 Ma) in outcrops of the north‐west Adriatic Carbonate Platform in Slovenia. Amidst environmental deterioration, the north‐west Adriatic Platform abruptly transitioned from a healthy, shallow‐water environment with diverse metazoan ecosystems to a partially drowned setting with low diversity biota and diminished sedimentation. An organic carbon‐isotope excursion of −2.2‰ reflects the massive injection of CO₂ into the ocean‐atmosphere system and marks the stratigraphic position of the Toarcian Oceanic Anoxic Event. A prominent dissolution horizon and suppressed carbonate deposition on the platform are interpreted to reflect transient shoaling of the carbonate compensation depth to unprecedentedly shallow levels as the dramatic influx of CO₂ overwhelmed the ocean’s buffering capacity, causing ocean acidification. Trace metal geochemistry and palaeoecology highlight water column deoxygenation, including the development of photic‐zone anoxia, preceding and during the Toarcian Oceanic Anoxic Event. Ocean acidification and reduced oxygen levels likely had a profoundly negative effect on carbonate‐producing biota and growth of the Adriatic Platform. These effects are consistent with the approximate doubling of the concentration of CO₂ in the ocean‐atmosphere system from pre‐event levels, which has previously been linked to a volcanic triggering mechanism. Mercury enrichments discovered in this study support a temporal and genetic link between volcanism, the Toarcian Oceanic Anoxic Event and the carbonate crisis.

中文翻译：

---

Toarcian海洋缺氧事件中的海洋酸化和光区缺氧：亚得里亚海碳酸盐台地的见解

严重的全球气候变化导致侏罗纪Toarcian阶段海洋环境条件恶化。今天暴露在高山特提斯山脉中的西特提斯海洋的碳酸盐台地提供了这一时期环境剧变的见识。除了深入了解气候变化外，古代碳循环扰动对碳酸盐台地的影响对人为气候变化也具有重要意义。早期Toarcian环境恶化的模式与现代海洋相似。这项研究的重点是早期的Toarcian海洋缺氧事件（ca斯洛文尼亚西北亚得里亚海碳酸盐台地露头183.1 Ma）。在环境恶化的情况下，西北亚得里亚海平台突然从具有后生动物生态系统的健康，浅水环境过渡到生物多样性低且沉积减少的部分淹死环境。有机碳-同位素偏移为-2.2‰，反映了向海洋-大气系统中大量注入了CO ₂，并标志了Toarcian海洋缺氧事件的地层位置。出色的溶解层位和抑制的碳酸盐沉积在平台上被解释为反映了随着CO _2的大量涌入，碳酸盐岩补偿深度的短暂暗挖达到前所未有的浅水平海洋的缓冲能力不堪重负，导致海洋酸化。痕量金属地球化学和古生态学突出显示了水柱脱氧，包括在Toarcian海洋缺氧事件发生之前和发生期间发生的光区缺氧。海洋酸化和氧气含量降低可能会对产生碳酸盐的生物群和亚得里亚海平台的生长产生深远的负面影响。这些影响与海洋大气系统中的CO ₂浓度相比事前水平大约翻了一番是一致的，而这之前曾与火山爆发机制有关。在这项研究中发现的汞富集支持了火山活动，Toarcian海洋缺氧事件和碳酸盐危机之间的时间和遗传联系。