Based on outcrop characteristics, combined with regional tectonic background, drilling and geophysical data, the sedimentary characteristics of the Middle Permian Maokou Formation in the northern Sichuan Basin was studied by means of macroscopic and microscopic observation, geochemical element test, total organic carbon content and vitrinite reflectance measurement. There is a set of deep-water sediments rich in organic matter in the Guangyuan-Wangcang area of northern Sichuan during the late depositional period of the Middle Permian Maokou Formation. The strata are distributed from northwest to southeast, with thickness of 10–30 m, mainly composed of siliceous rocks and siliceous mudstones, intercalated with gravity flow deposits. Siliceous rocks and siliceous mudstones are characterized by thin single layer, flat bedding and rich siliceous radiolarians, calthrop and brachiopod with small body and thin shell, belonging to the typical sedimentary characteristics of deep-water trough facies. The contents of Cu, Co, Mo, Ni and the ratio of Ni to Co in the geochemical tests all indicate that the siliceous rocks are products of deep-water reducing environment. The TOC value ranges from 3.21% to 8.19%, with an average of 5.53%, indicating that the siliceous rocks have good hydrocarbon generation ability. The south side of the trough is in platform margin facies with high energy, and the sediments are mainly thick massive micritic-calcsparite biogenic (clastic) limestone, which is conducive to the formation and evolution of the reservoir. During the late sedimentary period of the Maokou Formation, the northward subduction and extension of the oceanic crust at the northwestern margin of the Yangtze Plate provided the internal dynamic conditions for the formation of the “Guangyuan-Wangcang” trough. According to the location, sedimentary characteristics and formation dynamics of the trough, it is similar to the “Kaijiang-Liangping” trough during Late Permian proposed by previous researchers. It is believed that the “Kaijiang-Liangping” trough already had its embryonic form during the Late Middle Permian.

以露头特征为基础，结合区域构造背景、钻井和地球物理资料，通过宏观和微观观察、地球化学元素测试、总有机碳含量和镜质体等方法，对川北中二叠统茅口组沉积特征进行了研究。反射率测量。川北广元—望苍地区中二叠统茅口组沉积晚期发育一套富含有机质的深水沉积物。地层自西北向东南分布，厚度10～30 m，以硅质岩和硅质泥岩为主，夹有重力流沉积。硅质岩和硅质泥岩的特点是单层薄，层理平坦，富含硅质放射虫、鳞翅目、腕足类，体小壳薄，属于典型的深水槽相沉积特征。地球化学试验中Cu、Co、Mo、Ni的含量和Ni与Co的比值均表明硅质岩是深水减水环境的产物。TOC值为3.21%～8.19%，平均为5.53%，表明硅质岩具有良好的生烃能力。海槽南侧为高能量台地边缘相，沉积以厚块状泥晶-钙磷石生物（碎屑）灰岩为主，有利于储层的形成和演化。茅口组沉积晚期，扬子板块西北缘洋壳向北俯冲和伸展，为“广元-望苍”海槽的形成提供了内在动力条件。从海槽的位置、沉积特征和形成动力学来看，它与前人提出的晚二叠世“开江-梁坪”海槽相似。认为“开江-梁坪”海槽在中二叠世晚期已经形成雏形。