Lower Jurassic sedimentary successions in the Atlantic margin basins include several organic-rich intervals, some with source rock potential; time-equivalent units are also identified in on- and offshore areas worldwide. Despite decades of research, it is still unclear which mechanisms lead to the deposition of organic-rich sediments during the Early Jurassic. The objectives of this study are to construct a detailed temporal and geographical framework of Sinemurian–Toarcian organic matter preservation intervals (OMPIs; subdivided into local, regional, and superregional) and roughly constrain the relationship of OMPIs with the Lower Jurassic δ¹³C record. This survey combines an in-depth analysis of literature on the distribution of organic-rich facies in the Sinemurian–Toarcian with new geochemical studies [total organic carbon (TOC) and organic matter pyrolysis] from selected outcrop sections from Portugal, Spain, and Morocco.

Strong local control on OMPIs during most of the Sinemurian is suggested. Regionally widespread organic-rich facies are associated with the most negative δ¹³C values of the broad Sinemurian–Pliensbachian negative carbon isotopic trend recorded in organic matter (including the Sinemurian–Pliensbachian Boundary Event). Pliensbachian OMPIs are expressive in the areas bordering the proto-Atlantic Ocean and are often linked with positive δ¹³C excursions and short-lived warm intervals, but OMPIs are also defined for the Late Pliensbachian cool interval. Early Toarcian superregional OMPIs are associated with some of the most pronounced δ¹³C excursions of the Mesozoic. Toarcian maximum TOC content occurs with the positive δ¹³C (recovery) trend following the δ¹³C negative shift typically linked with the Early Toarcian Oceanic Anoxic Event (T-OAE), supporting the notion that peak carbon sequestration/ocean anoxia post-dated the main phase of carbon input into the atmosphere, as also suggested by recent modelling efforts. However, additional superregional OMPIs predate and postdate the T-OAE, indicating that conditions favouring preservation of organic matter (increased productivity and/or enhanced preservation) during the Early Toarcian were not restricted to the T-OAE interval.

The compilation of Sinemurian–Toarcian OMPIs presented in this paper demonstrates that organic-rich intervals of regional and superregional expression in the Lower Jurassic sedimentary record are ubiquitous and may even be more numerous than in the Cretaceous. Considering the association of some of the Sinemurian, Pliensbachian, and Toarcian (not taking into account the T-OAE related OMPIs) regional and superregional OMPIs with well-defined carbon isotopic excursions, it is here suggested that these hold the same relevance as the secondary OAEs of the Cretaceous, such as the Valanginian OAE (Weissert Event), Hauterivian OAE (Faraoni Event), and Late Aptian–Early Albian OAE (OAE 1b cluster).

大西洋边缘盆地的下侏罗统沉积层序包括几个富含有机质的层段，其中一些具有烃源岩潜力；世界各地的陆上和近海地区也确定了时间等效单位。尽管进行了数十年的研究，但仍不清楚是哪些机制导致早侏罗世富含有机质沉积物的沉积。本研究的目的是构建一个详细的 Sinemurian-Toarcian 有机质保存区间 (OMPIs; 细分为局部、区域和超区域) 的时间和地理框架，并粗略地约束 OMPIs 与下侏罗统 δ ^{13 的关系}C记录。本次调查结合了对 Sinemurian-Toarcian 富含有机物相分布的文献的深入分析，以及来自葡萄牙、西班牙和摩洛哥的选定露头剖面的新地球化学研究 [总有机碳 (TOC) 和有机质热解] .

建议在 Sinemurian 的大部分时间对 OMPI 进行强有力的本地控制。区域性广泛的富含有机物相与在有机质中记录的广泛的 Sinemurian-Pliensbachian 负碳同位素趋势（包括 Sinemurian-Pliensbachian 边界事件）中最负的 δ ¹³ C 值相关。Pliensbachian OMPI 在与原大西洋接壤的地区具有表现力，通常与正 δ ¹³ C 偏移和短暂的温暖间隔有关，但 OMPI 也被定义为晚 Pliensbachian 凉爽间隔。Toarcian 早期超区域 OMPI 与中生代一些最明显的 δ ¹³ C 偏移有关。Toarcian 最大 TOC 含量出现在正 δ ^{13 时}δ ¹³ C 负移后的 C（恢复）趋势通常与早期托阿西期海洋缺氧事件 (T-OAE) 相关，支持峰值碳封存/海洋缺氧晚于碳输入大气的主要阶段的观点，正如最近的建模工作所建议的那样。然而，额外的超区域 OMPI 早于和晚于 T-OAE，这表明在托阿尔西亚早期有利于有机质保存（提高生产力和/或增强保存）的条件不限于 T-OAE 间隔。

本文提出的 Sinemurian-Toarcian OMPI 的汇编表明，下侏罗统沉积记录中区域和超区域表达的富含有机质层段无处不在，甚至可能比白垩纪更多。考虑到一些 Sinemurian、Pliensbachian 和 Toarcian（不考虑与 T-OAE 相关的 OMPI）区域和超区域 OMPI 与定义明确的碳同位素偏移的关联，这里建议这些与次要的 OMPI 具有相同的相关性白垩纪的 OAE，例如 Valanginian OAE（Weissert 事件）、Hauterivian OAE（Faraoni 事件）和晚 Aptian-Early Albian OAE（OAE 1b 星团）。