Paleozoic tectonic evolution of the northern Xinjiang, China: Geochemical and geochronological constraints from the ophiolites

The northern Xinjiang of China is a composite orogenic belt in the south central part of the Altaids formed by subduction‐accretion mainly during the Paleozoic. Geochronologic and geochemical data from the Paleozoic ophiolites and associated assemblages are reported here to place constrains on the tectonic evolution of this region and to reconstruct its history, using a model of subduction‐accretion plus large‐scale map‐view strike‐slip faulting. Geologic and geochronologic review indicates that the Paleozoic ophiolites and associated assemblages of the western and eastern Junggar regions are tectonically related, occurring as a pattern with the early Paleozoic Tangbale‐Mayile‐Hongguleleng‐Aermantai complexes in the center, the late Paleozoic Darbut‐Karamaili and the northern Tianshan complexes in the south, and the late Paleozoic Kekesentao‐Qiaoxiahala‐Kuerti complexes in the north. Available geochemical data suggest that the Paleozoic ophiolites of the northern Xinjiang are mainly oceanic fragments of these three types: mid‐ocean ridge basalt, oceanic island basalts, and island arc basalts. The Paleozoic subduction‐accretion complexes grew mainly along different segments of the Kipchak arc, and in associated with migration of magmatic arc. The Paleozoic ophiolite‐associated sedimentary sequences and subduction‐related volcanic rocks exhibit an evolution history from intraoceanic (early Paleozoic) to marginal settings (late Paleozoic), implying coeval strike‐slip stacking with subduction‐accretion processes, and by which to transport the respective complexes together and further to amalgamate with neighboring units of the Altaids. Subduction‐accretion processes terminated in the mid‐Carboniferous in this region. In the late Permian‐early Triassic, a counterclockwise rotation of fault blocks in a giant sinistral strike‐slip and extension domain between Altay and Tianshan, lastly generated present configuration of the Paleozoic subduction‐accretion complexes in the northern Xinjiang.