Late Paleozoic-Early Mesozoic tectonic evolution of the Zongwulong Shan-Qinghai Nanshan tectonic belt in the northern Qaidam continent, northern Tibet

The Zongwulong Shan-Qinghai Nanshan tectonic belt of the northern Tibet Plateau experienced a protracted tectonic history, including the openings and closures of the Proto- and Paleo-Tethyan Oceans. Although the tectonic belt has been extensively studied, details regarding the tectonic processes involved in its development remain controversial. To better constrain the tectonic processes of this tectonic belt, we conducted detailed field geological mapping, zircon U-Pb geochronology, and whole-rock geochemical and Sr-Nd isotopic analyses. Our results show that intrusive rocks in the tectonic belt crystallized in ca. 292-233 Ma, perhaps in an arc/subduction setting. Geochemical and Sr-Nd isotopic data suggest that early Permian-late Triassic ultramafic-intermediate intrusions were sourced from the enriched mantle, whereas intermediate-acidic rocks were sourced from mixed crust-mantle. We present the tectonic model that involves: (1) Early Devonian- early Permian intracontinental extension occurred in the northern margin of the Qaidam continent (ca. 416 Ma-292 Ma); (2) Early Permian-late Triassic northward subduction of the Paleo-Tethyan Ocean resulted in arc magmatism (ca. 292 Ma-233 Ma); and (3) subsequent late Triassic intracontinental extension (ca. 233 Ma-215 Ma). Our results suggest that the late Paleozoic-early Mesozoic development of the Zongwulong Shan-Qinghai Nanshan was related to the opening, subduction, and slab retreat of the Paleo-Tethyan Ocean, which has key implications for the tectonic evolution of the northern Tibetan Plateau.