Abstract The Junggar basin is one of the most important oil producingareas in China. It is located in the northern part of Xinjiang Province and occupies an area of about140,000 km-, Commercial production comes mainly from the giant Karamay and associated oil fields at the northwest margin of the basin (Figure 1). Extensive exploration since 1980 has resulted in a series of new discoveries in other regions of the basin. The purpose of this paper is to document the lacustrine deposits of the Upper Permian Pingdiquan Formation in the eastern Junggar basin, which serves as both source and reservoir for the Huoshaoshan oil field (Figure 1). In the eastern part of Junggar basin, the thrust faulted Kelameili mountains are composed of Devonian and Carboniferous volcanic rocks plus derivativevolcaniclastic sedimentary rocks (Carroll et al., 1990).To the southwest, Permian and Mesozoic strata are exposed, forming several broad, gentle anticlines and synclines. Quaternary sands and gravels compose the dry river channels derived from the foothills of Kelameili. Zou (1984) first reported on the fan-deltadeposits of Pingdiquan Formation. In 1986/ ZhaoXiafei, together with his students, describedand measuredtwo lithologic sections in outcrop (Figure 2). At the same time, we did seismic stratigraphic studies toreveal the subsurface features of the Pingdiquan Formation.Liu and Zhao (1992) discussed the gravelly fandelta of Figure 2a and Wang et al. (1992) published the microfacies of the six producing horizons of the Pingdiquan Formation in the Huoshaoshan oil field. This paper documents the sedimentary paleo environment of the formation and examines the delta