Abstract One of the most profound environmental changes in the Mesozoic occurred during the Pliensbachian-Toarcian (Pl/To) time interval, including massive black shale deposition across Pl/To boundary and early Toarcian Oceanic Anoxic Event (T-OAE). These events are associated with negative carbon isotope excursions (CIEs), but their temporal link with 12C-rich carbon injection, possibly related with Karoo-Ferrar volcanisms and carbon cycle feedbacks, such as terrestrial methanogenesis and methane hydrate dissociation, is still debated. Here we present a new chemostratigraphy of the carbon isotopic ratio of organic matter (δ13Corg) from Pl/To deep-sea successions, in conjunction with bio-astrochronology. The deep-sea successions are located at the Katsuyama and Sakahogi outcrops in the Inuyama area, Japan, and contain two black bedded chert intervals named T-BBCs 1 and 2, which have astrochronologic ages of 183.25–183.01 ± 0.2 Ma and 183.55–182.80 ± 0.2 Ma. Negative CIEs of ~2‰ and ~5‰ are recognized across the base of T-BBCs 1 and 2, respectively, which are correlated with Pl/To boundary and classical T-OAE in shallow marine sections based on biostratigraphy. Astrochronologic ages of the onset of T-BBCs 1 and 2 are within the errors of the oldest high-precision U-Pb ages of Karoo and Ferrar LIPs, respectively. These temporal relations suggest a link between the 12C-rich carbon injection associated with Karoo and Ferrar volcanism, and CIEs associated with widespread black shale deposition across the Pl/To and T-OAE, respectively. Obliquity cycles in classic T-OAE CIE could have linked with terrestrial methanogenesis and methane hydrate dissociation in high-latitudes areas, whereas 405-kyr pacing of termination of T-CIE and T-BBCs deposition would be related with decreased chemical weathering and nutrient supply under weaker monsoon intensity, and possibly suppressed methane cycle across the termination of Pl/To and T-OAE periods.

中文翻译：

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与卡鲁-费拉火山活动和普连斯巴阶-托阿尔阶（侏罗纪早期）天文循环相关的碳循环动力学

摘要 中生代最深刻的环境变化之一发生在 Pliensbachian-Toarcian (Pl/To) 时间间隔期间，包括跨越 Pl/To 边界的大量黑色页岩沉积和早期 Toarcian 海洋缺氧事件 (T-OAE)。这些事件与碳同位素负偏移 (CIE) 相关，但它们与富含 12C 的碳注入的时间联系，可能与 Karoo-Ferrar 火山活动和碳循环反馈有关，例如陆地甲烷生成和甲烷水合物分解，仍存在争议。在这里，我们结合生物天文年代学，展示了来自 Pl/To 深海序列的有机质碳同位素比 (δ13Corg) 的新化学地层学。深海系列位于日本犬山地区的 Katsuyama 和 Sakahogi 露头，并包含两个名为 T-BBCs 1 和 2 的黑色层状燧石间隔，它们的天文年代年龄分别为 183.25–183.01 ± 0.2 Ma 和 183.55–182.80 ± 0.2 Ma。分别在 T-BBCs 1 和 2 的基部识别出~2‰ 和~5‰ 的负 CIE，它们与基于生物地层学的浅海海洋剖面中的 Pl/To 边界和经典 T-OAE 相关。T-BBCs 1 和 2 开始的天文年代学年龄分别在 Karoo 和 Ferrar LIPs 最古老的高精度 U-Pb 年龄的误差范围内。这些时间关系表明，与 Karoo 和 Ferrar 火山活动相关的富含 12C 的碳注入与分别与 Pl/To 和 T-OAE 上广泛的黑色页岩沉积相关的 CIE 之间存在联系。