川东—武陵山地区下寒武统牛蹄塘组页岩有机质富集模式

有机质富集、保存对页岩气资源评价、勘探选区和开发具有重大的指导意义。以川东—武陵山地区下寒武统牛蹄塘组页岩为例，利用岩石地球化学、油气地球化学和沉积岩石学方法和技术对牛蹄塘组有机质丰度、有机质来源及古环境演化进行了分析，对川东—武陵山地区页岩有机质富集和保存条件进行了评价。结果表明:牛蹄塘组页岩有机质主要来自于蓝藻、红藻、褐藻等自生海洋藻类；相比于牛蹄塘组高位体系域，在牛蹄塘组海侵体系域页岩沉积期，温暖湿润的古气候和大规模海侵使得海平面快速上升，海侵导致深水陆棚、斜坡甚至部浅水陆棚处于贫氧—缺氧环境，该深水贫氧—缺氧还原环境（部分硫化还原环境）有利于有机质保存，在川东—武陵山地区上形成大面积富有机质页岩。 

ACCUMULATION PATTERN OF ORGANIC MATTER IN SHALES OF THE LOWER CAMBRIAN NIUTITANG FORMATION, CHUANDONG-WULINGSHAN AREA

The accumulation and preservation of organic matter have great guiding significance for the evaluation of oil and gas reservoirs and the survey and exploration of targeting exploration area. Based on the technologies and methods of lithogeochemistry, petroleum geochemistry and sedimentology, the richness and source of organic matter and paleoenviroment evolution of the Lower Cambrian Niutitang Formation in Chuandong-Wulingshan area were analyzed. The enrichment and preservation conditions of organic matter were evaluated preliminarily. The results show that planktonic algae (including blue-green algae, rhodophyta and phaeophyta) are the primary producers of organic matter. Compared with the upper domain of Niutitang Formation, during the deposition period of transgression, the warm and humid paleoclimate and large-scale transgression made the sea level rise rapidly, and the transgression caused deep continental shelf, slope and even shallow continental shelf to be in an oxygen-deficient or anoxic environment. This deep water oxygen-deficient and anoxic reduction environment (partial sulfide reduction environment) is favorable for the preservation of organic matter, and a large area of organic-rich shales were formed in the area of Chuandong-Wulingshan area.