Late Palaeozoic Intrusive Magmatism and Late Mesozoic Tectonic Transition in the Chaheilingashun Area, Northwestern Zhusileng–Hangwula Tectonic Belt, <scp>NW</scp> China

ABSTRACT The intracontinental deformation is an essential element of the tectonic evolution of the Central Asian Orogenic Belt (CAOB) during the Late Mesozoic. Located along the Mid‐southern CAOB, the Zhusileng–Hangwula tectonic belt connects the Beishan Orogenic Belt and the Solonker Suture. However, the chronological constraints of Mesozoic history on this region remain unclear. Here, we presented field observations, geochemical characteristics and low‐temperature thermochronometry (apatite fission track, AFT) results from the Chaheilingashun area (northwestern Zhusileng–Hangwula tectonic belt) to constrain the regional tectonic history. The whole‐rock geochemical data indicate that the Middle Devonian Chaheilingashun monzogranite pluton is a (high‐K) calc‐alkaline S‐type granitoid. This pluton most likely formed in a postcollisional setting during the Middle–Late Devonian. New AFT data and thermal history modelling of the Chaheilingashun pluton suggest that the region experienced rapid cooling and exhumation events (135–133 Ma). The regional Mid–Late Jurassic contractional deformation (termed phase B of Yanshanian deformation) could have lasted until the earliest Early Cretaceous. Following this shortening event, regional extension was widespread in the mid‐southern CAOB, as evidenced by rift‐related magmatism, metamorphic core complexes and widespread concurrence of extensional basins. Therefore, we suggest that the Early Cretaceous tectonic transition (from contraction to extension) could have occurred at 133 Ma in the Zhusileng–Hangwula tectonic belt. In addition, this transition could have resulted from multiple factors related to the far‐field effects of oceanic plate subduction.