Abstract:

The palaeotectonic framework of the Tarim basin in the Early Paleozoic was characterized by development of a series of large-scale,NWW or NEE trending uplifts.The configuration of the uplifts and the depressions varied significantly and resulted in the change of the tectonic paleogeography of the basin.The paleohigh belt in the central basin was formed when the basin shifted from divergence to compression since the Middle Ordovician.It comprises the Hetianhedong and Tazhong palaeo-uplifts with complex paleogeomorphology.Several typical geomorphologic units have been recognized in the early Paleozoic paleohighs,including the uplift high,marginal slope and slopebreak,shelf gentle slope and lower rise or platform,shelf slopebreak and deep-sea basin or plain.The southern marginal slopebreak zone of the Tabei paleohigh,and both the northern and southern slopebreak zones flanking the Tazhong paleohigh controlled the development of high-energy facies of reef and shoal deposits.From the paleohighs to the paleo-depression belt,the marginal slopebreak zones of carbonate platforms,triangle zones of truncated and onlap unconformities are favorable for the formation of lithologic-stratigraphic traps.

Key words: Paleouplift geomorphology, tectonic paleo-geography, unconformity distribution, Eopaleozoic, Ta-rim Basin