| On the basis of collecting the data of typical hydrothermal sedimentary outcrops of the Cambrian Qiongzhusi
Formation in the northern Yunnan and Guizhou, the development characteristics of source rocks in the study area were
deeply explored through pyrolysis, TOC, saturated hydrocarbon chromatography-mass spectrometry, trace elements and
rare earth elements and other experimental analysis, and the biomarker assemblages of modern marine hydrothermal
organisms and sediments were compared with unique biomarker distribution characteristics of the Cambrian source rocks
and generated crude oil in Sichuan Basin and Tarim Basin. The results show that: (1) Hydrothermal deposition are
developed during the sedimentary period of Qiongzhusi Formation in northern Yunnan and Guizhou, and the rich nutrients
and strong reduction conditions in the hot water environment are conducive to the prosperity of organisms and the
preservation of sedimentary organic matter, which is conducive to the formation of high-quality source rocks. (2) Shale
source rocks of continental shelf are widely developed in the Qiongzhusi Formation in the north of Yunnan and Guizhou,
and the development of high-quality source rocks is mostly related to hydrothermal deposition. The formation and
preservation conditions of source rocks in hot deep water environment are better. The organic matter abundance of hot
shallow water shelf source rocks is high, TOC is between 2% and 5%; the abundance of organic matter in hot deep water
shelf source rocks is higher, and TOC is between 5% and 10% or more than 10%. (3) The thermal evolution of the source
rock of Qiongzhusi Formation in the north of Yunnan and Guizhou is high, and it is in the over-mature evolution stage,
with good shale gas resource potential. The total amount of shale gas resources of South Sichuan Low-Steep Fold Belt
and Weixin Depression in southern Sichuan is 6 589.5×108 m3, indicating they are potential shale gas exploration zones.
(4) Hydrothermal sedimentary source rocks are widespread in the Cambrian in Sichuan, Tarim and other basins. Besides
the continental shelf, the deep-sea basin also has the material basis and preservation conditions for source rocks, and may
also develop high-quality source rocks. |
