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中国南方茅口组地层为区域性烃源岩.茅口组底部和顶部均发育硅质岩,顶部地层残余有机碳高达10.90%,其厚度16m,为优质烃源岩层,而该组底部为差烃源岩.通过岩石学、碳同位素和微量元素分析,表明华南川西北地区茅口期存在2期上升流,分别发育于茅口组沉积早期和晚期;上升流所带来的营养盐有利于生物的发育,产生高的初级生产力.结合碳同位素资料,发现茅口期古海洋生物产率呈现出高-低-高的变化过程,而大气中CO2含量变化也呈现高-低-高的变化过程.虽然茅口期底部为高初级生产力层段,但是由于该沉积及早期成岩阶段为常氧环境,不利于沉积有机质保存,形成了差烃源岩,而茅口组顶部沉积时期存在大的海侵事件,海平面的上升导致厌氧环境形成,沉积有机质大量保存下来,形成优质烃源岩层段.该套烃源岩形成与发育主控因素分析是中国南方海相优质烃源岩分布预测和油气成藏研究的基础.
The Maokou Formation in southern China is a regional source rock, with chert on the bottom and top of the Maokou Formation. The residual organic carbon in the top layer reaches 10.90% with a thickness of 16 m, which is a high-quality source rock formation with the bottom of the group being poor Source rock.According to petrology, carbon isotope and trace element analysis, it shows that there are two up-flow in Maokou period in northwestern South China, which are respectively developed in the early and late sediments of Maokou Formation. Nutrients brought by upwelling are favorable to Bio-development and high-level primary productivity.Based on the carbon isotope data, it was found that the productivity of paleo-marine organisms in Maokou period showed a high-low-high change process, while the atmospheric CO 2 content also showed a high-low-high change Although the bottom of Maokou period is high primary productive interval, due to the normal oxygen environment in the sedimentary and early diagenesis stage, it is not conducive to the preservation of sedimentary organic matter, resulting in the formation of poor source rock, while the top of Maokou Formation has large In the case of transgression, sea level rise led to the formation of anaerobic environment, and the deposited organic matter was preserved in a large amount to form high quality source rock strata. The main controlling factor for the formation and development of this source rock is the high quality source rock Cloth prediction and hydrocarbon basis Tibetan studies.