受地层剥蚀和强烈构造活动的影响，对中扬子东南缘前陆坳陷区五峰‒龙马溪组黑色岩系关注较少，该区黑色岩系沉积特征与有机质富集规律尚不清楚.利用近年来新获取的常德TD2井岩心资料，基于岩石学、沉积学以及地球化学分析，对湘西前陆坳陷区五峰‒龙马溪组黑色岩系的发育特征、沉积环境及有机质富集机制开展了深入研究.结果表明，湘西前陆坳陷区TD2井五峰‒龙马溪组黑色岩系厚度较大，TOC>2%的富有机质页岩厚约21 m，岩性以硅质页岩与碳质页岩为主，基于岩性差异自下而上可划分为四个沉积单元，富有机质页岩主要集中凯迪阶至鲁丹阶下部，而鲁丹阶上部‒埃隆阶下部黑色岩系TOC含量普遍偏低且呈间断发育.综合研究认为，前陆坳陷区五峰‒龙马溪组黑色岩系的形成主要受构造、海平面以及陆源碎屑供给等因素的综合控制.凯迪晚期‒鲁丹早期，受区域构造挤压和全球海平面上升的影响，湘西地区经历了显著的构造沉降及相对海平面上升等事件，极大地促进了坳陷区强还原条件的形成以及古生产力的提高，使得该时期研究区黑色岩系中的有机质大量富集.然而，随着鲁丹晚期区域构造挤压活动的加剧，研究区由构造沉降向构造隆升转变，持续的构造抬升与风化作用增强，导致了研究区陆源碎屑供给大量增加和相对海平面不断下降，并最终使得研究区富有机质页岩的形成发育在埃隆早期被终结.值得注意的是，埃隆早期的全球冰川型海平面上升在研究区也有响应，促进了龙马溪组黑色页岩的二次发育.据此，提出了湘西前陆坳陷区奥陶‒志留纪之交富有机质页岩的发育模式，以期为该区五峰‒龙马溪组页岩气勘探及奥陶‒志留纪之交重大地质事件沉积响应研究提供参考.

As the main sediments across the Yangtze area during the Ordovician-Silurian (O-S) transition, the Upper Ordovician Wufeng Formation and Lower Longmaxi Formation are widely distributed in the Yangtze Sea, and they are also the main targets for marine shale gas exploration in the South China. However, little attention has been paid to the Wufeng-Longmaxi black rock series in the foreland basin, southeastern Yangtze Block, due to the lack of complete and fresh outcrops caused by intensive erosion and tectonic damage. In this paper, by utilizing the newly obtained drilling cores of the Well TD2 located in the Hunan Province, the sedimentary environment and organic matter accumulation of the Wufeng-Longmaxi black rock series in the foreland basin were investigated based on the systematically petrological and geochemical analysis. The organic-rich shale of the Wufeng-Longmaxi formations is dominated by siliceous shale and carbonaceous shale, in which plenty of terrigenous clast and even thin sandstone can be observed. The black shale with TOC>2% is about 21 m in thickness. Four sedimentary cycles can be recognized from the O-S black series and they exhibit different lithological and geochemical variation characteristics. The organic shale generally developed in the Late Katian to the Early Rhuddanian, while the black rock series developed during the Late Rhuddanian to Early Aeronian have low TOC content and are discontinuous. Based on the analyses of lithology, mineral composition and geochemistry, tectonism, sea-level and terrigenous supply should be the primary controlling factors for the deposition of the O-S black shale in the foreland basin, Yangtze area. During the Late Katian to Early Rhuddanian, the study area experienced significantly tectonic subsidence and sea-level rise caused by regional tectonic compression and global sea-level rise, then strongly reducing conditions were formed and paleoproductivity was improved in the deep-depression area, which promoted the enrichment of organic matter in black rock series during this stage. Nevertheless, with intensifying tectonic collision between the Yangtze and Cathaysia blocks since Late Rhuddanian, the tectonism in the study area changed from tectonic subsidence to uplift. Persistent tectonic uplift and intensive weathering conditions led to the noticeable increase of terrigenous supply in the foreland depression, as well as gradual sea-level fall, and then, the development of black organic-rich shale in the foreland basin was terminated at the Early Aeronian. It should be noted that during the earliest Aeronian stage, global glacial sea-level rise promotes the development of black shale in the study area again. Finally, a sedimentary model for the O-S black shale in the foreland depression, western Hunan area was proposed. This study is not only beneficial for gaining more geological knowledge about the black shale formation in a marine foreland basin, but also helpful for understanding the sedimentary responses to major geological events occurred in Yangtze area during the O-S transition.