Provenance of Late Carboniferous–Triassic clastic rocks in the Western Kunlun orogenic belt, western China: Implications for the tectonic evolution of the Paleo-Tethys Ocean

Abstract

The Western Kunlun orogenic belt in the northwest Tibetan Plateau is composed of the North Kunlun, South Kunlun, Tianshuihai, and Karakorum terranes, and has records about the tectonic evolution of the Paleo-Tethys Ocean. To provide new insights into the Paleo-Tethys orogeny in Western Kunlun, we present detrital zircon U-Pb and Lu-Hf isotopic data from the Late Carboniferous–Triassic sedimentary successions in the Tianshuihai terrane. Zircons with ages of 350–250 Ma are abundant in the Late Carboniferous–Late Permian samples and yielded εHf(t) values ranging from + 14.9 to −18.9. This indicates continuous arc-related magmatism in the Tianshuihai terrane during the Early Carboniferous–Late Permian. The Upper Permian Huangyangling Group primarily comprised Paleozoic detrital zircons predominantly sourced from the Tianshuihai terrane. Other strata contain higher proportion of Precambrian detrital zircons compared to the Huangyangling Group. This feature indicates that detritus from these strata were primarily originated from the North Kunlun, South Kunlun, and Tianshuihai terranes. We present a synthesis of provenance analysis, late Paleozoic–Triassic magmatic rocks, and Triassic metamorphic records associated with the Mazha–Kangxiwa suture zone. These data indicate that the Paleo-Tethys Ocean between the South Kunlun and Tianshuihai terranes opened at ca. 350 Ma and closed during the Middle Triassic, following continuous Carboniferous–Early Triassic subduction. Our study provides an important example of the provenance of clastic rocks in the orogen, which can be used to reconstruct information about eroded magmatic rocks and provide insights into the tectonic evolution of the orogen.