Aromatic compounds in crude oils and source rocks and their application to oil–source rock correlations in the Tarim basin, NW China Li Jinggui a , Paul Philp b, * , Meng Zifang a , Liu Wenhui a , Zheng Jianjing a , Chen Guojun a , Li Mei c , Wang Zhaoyun d a State Key Laboratory of Gas Geochemistry, Lanzhou Institute of Geology, Chinese Academy of Sciences, Lanzhou 730000, China b School of Geology and Geophysics, University of Oklahoma, Norman, OK 73019, USA c Research Institute of Exploration and Development, Tarim Oil Field, PetroChina, Kuerle 841000, China d Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China Received 8 January 2003; revised 9 January 2004; accepted 23 January 2004 Abstract Ten series of aromatic hydrocarbons (biphenyls; naphthalenes; phenanthrenes; anthracenes; retenes; chrysenes; benzoanthracenes; dibenzofurans; fluorenes; and dibenzothiophenes) isolated from Cambrian and Ordovician marine carbonate source rocks in Tabei and Tazhong areas of the Tarim Basin, and Triassic and Jurassic lacustrine mudstones and swamp coals in the Kuche depression have been characterized by GC-MS. The same series of aromatic compounds have been isolated and characterized from crude oils of the Tabei and Tazhong uplift. Results presented in this paper describe the distribution of these aromatic compounds in crude oils and source rocks from the three different kinds of sedimentary environments. Similarities in distributions of the fluorenes and the dibenzothiophenes in the aromatic fractions suggest the Tabei uplift oils are derived predominantly from the Lower Ordovician marine source rocks of Tabei Lunnan area (on the south of Luntai) and the oils from Tazhong uplift are mainly derived from Upper Cambrian, Lower Ordovician, and Middle –Upper Ordovician marine source rocks of Tazhong area. q 2004 Elsevier Ltd. All rights reserved. Keywords: China; Tarim basin; Kuche depression; Tabei uplift; Tahzong uplift; Terrestrial; Triassic; Jurassic; Marine; Cambrian; Ordovician; Aromatic hydrocarbons; Fluorene; Dibenzothiophene 1. Introduction The Tarim basin, NW China, is the only basin in China with economic accumulations of oil and gas derived from both terrestrial and marine source rocks. The Lower Paleozoic Erathem Formation of the Tarim basin contains economic accumulations of gas as well as oil derived from marine source rocks. Oil and gas accumulations derived from terrestrial sources and characterized by gas condensate reservoirs, have been found in the Kuche depression in the northern part of the basin, and its front uplift area. The source rocks for oil and gas of terrestrial origin are Triassic and Jurassic dark lacustrine mudstone facies and coal swamp facies. The organic matter in the source rocks from the eastern part of the depression is mature to highly mature, whereas the organic matter of source rocks in western depression center zones is highly mature to overmature (R o : 1.3 – 2.5%) resulting from 8 km of overlying Cretaceous and Tertiary sedimentary accumulations (Huang et al., 1999), leading to a series of terrestrially derived condensate-gas pools such as that observed at Kela 2 (Fig. 1). Marine oil and gas pools in the Tarim basin are found mainly in the Tabei and Tazhong uplift areas, with their source rocks thought to be Cambrian and Ordovician carbonate rocks. In view of the age, high levels of maturity and low TOC contents (generally , 0.2%) of most marine carbonate rocks in Chinese Basins, several Chinese geochemists have suggested that marine carbonate rocks with TOC . 0.1% must be potential source rocks in order to account for all the oil derived from carbonate source rocks. Liang et al. (1998) and Zhang et al. (2000a) described two source rocks (TOC $ 0.5%) in Cambrian and Ordovician carbonate rock strata with a thickness of 5–7 km. One of 1367-9120/$ - see front matter q 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jseaes.2004.01.019 Journal of Asian Earth Sciences 25 (2005) 251–268 www.elsevier.com/locate/jaes * Corresponding author. E-mail address: pphilp@ou.edu (P. Philp).