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大巴山地区早古生代发育下寒武统水井沱组(巴山组—鲁家坪组)和上奥陶统五峰组—下志留统龙马溪组2套黑色岩系。沉积学研究表明,2套黑色岩系均发育于扬子北缘被动大陆边缘盆地之上,早期快速海侵,沉积环境以深水陆棚为主,晚期随着海平面下降逐渐变为浅水陆棚沉积,局部发育滩礁沉积。早寒武世和晚奥陶世—早志留世,研究区均处于被动大陆边缘盆地,基底不平整,陆架边缘呈现多个小岛阻隔的古地理格局,但两者的形成机制却完全不同:早寒武世的构造格局沿袭了陡山沱期的地堑和地垒分布格局,地垒处表现为局部隆起或水下潜隆;晚奥陶世—早志留世的构造格局则与扬子板块向华北板块俯冲有关,是在扬子北缘被动大陆边缘基础上发育起来的前陆隆起。这种受限的滞留海域有利于形成厚度大、有机碳含量高(2%~6%)、脆性矿物含量高(40%~65%)的富有机质页岩,虽然其是页岩气勘探的有利目标层系,但仍需加强构造保存条件的研究。
Early Paleozoic in the Dabashan area developed two sets of black rock series of Lower Cambrian Shuijingtuo Formation (Bashan Formation - Lujiaping Formation) and Upper Ordovician Wufeng Formation - Lower Silurian Longmaxi Formation. Sedimentology studies show that two sets of black rock series developed above the passive continental margins in the northern margin of the Yangtze River. Early rapid transgression and sedimentary environment were dominated by deep-water shelf. Later, as the sea level decreased, Local development of beach reef deposition. The Early Cambrian and late Ordovician - Early Silurian both located in the passive continental marginal basin with uneven basement and multiple paleogeographic barriers at the edge of the shelf, but the formation mechanism of the two is completely different: The structural pattern of the Early Cambrian follows the distribution pattern of the graben and basement in the Doushantuo period, with local uplifts or submarine submersion at the basement. The structural pattern of the Late Ordovician-early Silurian was similar to that of the Yangtze Plate Subduction to the North China Plate is related to the uplift of the foreland developed on the passive continental margin on the northern margin of the Yangtze. This limited sea area is favorable for the formation of organic-rich shales with thick, high organic carbon (2% to 6%) and high levels of brittle minerals (40% to 65%) although these are shale gas exploration Favorable target strata, but still need to strengthen the study of structural preservation conditions.