Geochronic and Geographic Distribution of Nonmarine Petroleum Source Rocks

Abstract

The study of the petroleum sporo-pollen assemblages and the correlations between spores and pollen in crude oils and those in potential source rocks is a powerful tool to determine the petroleum source rock series in the petroliferous basins of China. Certain generalizations can be made: Upper Paleozoic, Mesozoic, and Tertiary rocks in the petroliferous basins of China expelled petroleum. Tropical or subtropical lacustrine deposition was the favorable climatic and ecological setting for the formation of petroleum source rocks in the continental basins. In the inland petroliferous basins, such as the Turpan and Qaidam basins, Jurassic petroleum source rocks formed in lacustrine and swampy environments are important and abundant. In the large superimposed basins of the inland petroliferous basins, such as the Tarim and Junggar basins, the petroliferous regions possess Carboniferous, Permian, Triassic, Jurassic, and Paleogene petroleum source rocks formed in a limnetic sedimentary environment. The coastal shelf petroliferous basins, including the Liaohe, Beibu Gulf, Zhujiang Mouth, and Sanshui basins, contain Paleogene source rocks formed mainly in lacustrine settings. Dark-colored argillaceous rocks and oil shales, considered to be excellent petroleum source rocks, are common in these coastal shelf basins. Thus, the study of sporo-pollen in crude oils has added significant information to enhancing petroleum exploration in petroliferous basins.