Tracing provenances of detrital zircons in the South Tianshan and northern Tarim Craton : constraints on Paleozoic-Mesozoic evolution of the southern Central Asian Orogenic Belt

The South Tianshan (STS) Orogenic Belt represents a suture zone resulting from the collision of the Tarim Craton with the southern Central Asian Orogenic Belt (CAOB). Controversy has long surrounded the timing and process during the development and consumption of the intervening oceanic domain, namely the STS Ocean, and the resultant continental collision throughout Paleozoic-Mesozoic time. This project attempts to address these issues by integrating detrital zircon provenance analysis with preexisting geological and geochronological data. A further extension of this research suggests a spatial and temporal coupling between accretion-collision tectonics along the periphery of the Tarim and North China cratons and the assembly and dispersal of northeastern Gondwana. Zircon U-Pb-Hf data indicate that Silurian-Early Devonian strata in the northwestern Tarim region have detrital zircon age spectra and εHf(t) values matching those of magmatic rocks in the Tarim Craton and Central Tianshan (CTS) Block. Abundant 500-400 Ma detrital zircons in these strata were probably shed from a magmatic arc built upon the once-united CTS Block and northern Tarim margin. The separation between them most likely occurred in the Early Devonian, as implied by the contrast between the absence of