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萍乐坳陷西部中古生界海相区块勘探与研究程度较低。通过系统的野外露头和煤矿采样、室内化验分析以及初步的地球化学研究，认为：下二叠统栖霞组、小江边组、茅口组碳酸盐岩夹碳质泥岩、泥页岩及上二叠统煤系地层为萍乐坳陷西部主要烃源岩层，下二叠统海相烃源岩丰度可以与四川、黔南、桂中、塔里木等已知含油气区（或古油藏）的海相烃源岩相比美，岩性和演化程度是影响烃源岩丰度的主要因素。萍乐坳陷西部地区烃源岩演化程度总体偏高，达到高成熟—过成熟演化阶段，造成该区烃源岩高演化程度的主要地质作用有深成变质作用、岩浆热烘烤作用及构造应力变质作用等。萍乐坳陷西部二叠系生储盖组合较为有利，虽然其烃源岩演化程度总体偏高，但仍分布有镜质体反射率仅为0.81%~1.51%演化程度适中的烃源岩，而且国内外也已经在烃源岩高演化地区发现了大量的大型天然气藏，因此总体评价研究区是一个有潜力的天然气勘探远景区，今后应进一步加强研究和勘探。

ASSESSMENT OF THE HYDROCARBON SOURCE ROCKS IN UPPER PALEOZOIC-LOWER TRIASSIC IN WEST PINGLE DEPRESSION

The exploration and research levels of Middle Paleozoic marine strata are low in West Pingle Depression. On the basis of systematically sampling at the field outcrops and in the coal mines and through laboratory chemical analysis and preliminary geochemical research， it was considered that the carbonate rocks interbedded by carbonaceous mudstones and mud shales of the Qixia Formation， Xiaojiangbian Formation and Maokou Formation of Low Permian and the coal measure strata of Upper permian are the main hydrocarbon source rocks in West Pingle Depression； the organic matter abundances in the marine hydrocarbon source rocks of Lower Permian can be compared favourably with those of the known oil and gas bearing regions (or ancient oil reservoirs) in Sichuan， South Guizhou， Middle Guangxi and Talimu Basin； the lithology and evolution level are the principal factors affecting the organic matter abundance in bydrocarbon source rocks； the evolution level of hydrocarbon source rocks in West Pingle Depression is on the high side overall， being up to high maturity postmaturity； and the main geological functions causing the high evolution level include plutonic metamorphism， magmatic baking out and tectonic stress metamorphism， etc. The source reservoir caprock assemblage of Permian in West Pingle Depression is relatively favourable. Although the evolution level of its hydrocarbon source rocks is on the high side， there still exist the hydrocarbon source rocks of moderate evolution level with Ro of 0.81—1.51% there， and a great number of large gas reservoirs have been found out in the areas with high evolution hydrocarbon source rocks at home and abroad. Therefore， according to the comprehensive assessment result， the West Pingle Depression is a prospective region with great potentiality for gas exploration and the research and exploration activity should be further strengthened in the future.