Abstract The end Pliensbachian–Toarcian is characterized by several carbon-cycle perturbations and faunal turnovers (e.g., ammonites and foraminifera), which are most likely triggered by pulses of the Karoo-Ferrar-Chon Aike large igneous province. The majority of information about these events is based on detailed studies of sites deposited in deep-water settings, which leaves vast uncertainties about the expression of, and response to, these events in shallow-marine ecosystems. Here, we present a comprehensive assessment of paleoclimatic impacts on neritic depositional environments from the latest Pliensbachian through the middle Toarcian in the central High Atlas Basin, Morocco, and compare those with changes observed in coeval neritic environments within the western Tethyan realm. A total of four new stratigraphic sections were investigated in the southern part of central High Atlas Basin and these new sections are synthesized with six previously published sections, distributed over eight localities. Correlations between sections are based on biostratigraphy, chemostratigraphy and lithostratigraphy. In Morocco, two episodes of carbonate factory shutdown are observed, spanning the Pliensbachian/Toarcian boundary and the Polymorphum/Levisoni transition. Each carbonate factory collapse correlates to well-documented environmental disturbances during the latest Pliensbachian–middle Toarcian interval, including the Toarcian Oceanic Anoxic Event (T-OAE). Moreover, each episode of carbonate factory shutdown coincides with an interval characterized by a significant increase of coarse siliciclastic input in the basin, further demonstrating the link between global warming, increased continental weathering, and ecosystem turnovers. Furthermore, these two episodes of carbonate factory shutdown are each followed by episodes of renewed carbonate production, showing the resilience of the neritic carbonate factory in this region. The first recovery interval, occurring during the late Polymorphum Zone, is associated with a mixed siliciclastic‑carbonate system. The second episode of carbonate recovery quickly follows the shutdown associated with the onset of the T-OAE. It is associated with an abiotic-dominated carbonate production mode, resulting in an elevated ooid production. A full recovery of biotic carbonate production only occurs in the late stage of the T-OAE. Although biotic turnover occurs at both events, from a shallow-marine perspective, the major biotic and abiotic crisis occurred at the Pliensbachian/Toarcian boundary and not during the T-OAE. This is in contrast to the deep-marine record, where the T-OAE is often inferred to be the most significant event. An enhanced hydrological cycle and the subsequent increase of continental nutrient shedding might have triggered the most severe changes of the carbonate productivity at the Pliensbachian/Toarcian transition; whereas, ocean acidification and increased storm activity likely played a significant role at the onset of the T-OAE.

中文翻译：

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冈瓦纳陆缘西北缘气候变化和大陆风化作用增强的普连斯巴阶-托阿尔阶晚期浅水碳酸盐工厂的两阶段坍塌

摘要 Pliensbachian-Toarcian 末期的特征是几个碳循环扰动和动物群转换（例如菊石和有孔虫），这很可能是由 Karoo-Ferrar-Chon Aike 大型火成岩省的脉冲触发的。关于这些事件的大部分信息是基于对沉积在深水环境中的地点的详细研究，这给浅海生态系统中这些事件的表达和响应留下了巨大的不确定性。在这里，我们综合评估了古气候对摩洛哥高阿特拉斯盆地中部从最新的 Pliensbachian 到中 Toarcian 浅海沉积环境的影响，并比较了在西特提斯领域的同时期浅海环境中观察到的变化。在高阿特拉斯盆地中部的南部总共调查了四个新的地层剖面，这些新剖面与分布在八个地点的六个先前发表的剖面合成。剖面之间的相关性基于生物地层学、化学地层学和岩石地层学。在摩洛哥，观察到两次碳酸盐工厂停工，跨越 Pliensbachian/Toarcian 边界和 Polymorphum/Levisoni 过渡。每个碳酸盐工厂的倒塌都与最近的 Pliensbachian-middle Toarcian 间隔期间有据可查的环境干扰有关，包括 Toarcian 海洋缺氧事件 (T-OAE)。此外，碳酸盐工厂停产的每一期都与盆地中粗硅质碎屑输入显着增加的间隔相吻合，进一步证明了全球变暖、大陆风化加剧和生态系统更替之间的联系。此外，在这两次碳酸盐工厂停产事件之后，均出现了碳酸盐岩恢复生产的事件，显示了该地区浅海碳酸盐工厂的韧性。第一个采收间隔发生在晚多形带期间，与混合硅质碎屑-碳酸盐系统有关。在与 T-OAE 开始相关的关闭之后，第二次碳酸盐回收事件很快发生。它与非生物主导的碳酸盐生产模式有关，导致鲕类产量增加。生物碳酸盐生产的完全恢复仅发生在 T-OAE 后期。尽管在这两个事件中都会发生生物周转，但从浅海的角度来看，主要的生物和非生物危机发生在 Pliensbachian/Toarcian 边界，而不是在 T-OAE 期间。这与深海记录形成对比，在深海记录中，T-OAE 通常被推断为最重要的事件。增强的水文循环和随后大陆养分流失的增加可能引发了 Pliensbachian/Toarcian 过渡期碳酸盐生产力的最严重变化；而海洋酸化和风暴活动增加可能在 T-OAE 开始时发挥了重要作用。增强的水文循环和随后大陆养分流失的增加可能引发了 Pliensbachian/Toarcian 过渡期碳酸盐生产力的最严重变化；而海洋酸化和风暴活动增加可能在 T-OAE 开始时发挥了重要作用。增强的水文循环和随后大陆养分流失的增加可能引发了 Pliensbachian/Toarcian 过渡期碳酸盐生产力的最严重变化；而海洋酸化和风暴活动增加可能在 T-OAE 开始时发挥了重要作用。