Carboniferous tectonic configuration of the Yining Massif in Western Tianshan, NW China

Abstract

The tectonic evolution and configuration of the Carboniferous trench‐arc‐basin system (TABS) in the Yining Massif (Western Tianshan, NW China) have long been controversial. The question of the existence of an ancient ocean basin and its subduction polarity is crucial to address this issue. In this study, we suggest that the Early Carboniferous calc‐alkaline volcano‐sedimentary rocks were formed in a fore‐arc/back‐arc basin system, whereas the Late Carboniferous bimodal volcanic rocks and their associated sedimentary rocks were formed under a continental rift setting after the Junggar‐Tarim collision. We propose that the Southern Tianshan ocean basin may have closed in the Late Early Carboniferous, terminating the TABS at Yining. Spatial–temporal distribution of volcanic‐sedimentary rock assemblages suggests that the Early Carboniferous Southern Tianshan ancient ocean basin was similar to the TABS system of the present‐day Japanese island arc.

Petrogenesis of Early Carboniferous Alkaline Basalt from the Wusun Mountain: Implications for Tectonic Evolution of the Western Yining Block, NW China

“…In contrast, the Late Carboniferous volcanic rocks show distinct differences in rock assemblages, geochemistry and tectonic settings. They are dominated by alkaline rocks and tholeiitic basalts (Li et al, 2018b). A remarkable feature of the Late Carboniferous volcanism is the occurrence of typical bimodal volcanic suites at the Wusun Mountain, Yining Block, with zircon U-Pb ages of ca.…”

“…The C 1 a shows neritic, marine-continental transitional affinities, and massive carbonates, sandstones and siltstones, as well as a well-developed rich assemblage of shallow-water fossils (Bai et al, 2015). Relative to the C 1 d, the C 2 y is dominated by a typical bimodal volcanic suite related to continental lift (Li et al, 2018b;Ning et al, 2019). In addition, Permian to Jurassic strata overlie the Carboniferous outcrop and Late Devonian to Permian granitoids are also exposed in this area, which occur as small plutons or dikes intruding the Late Paleozoic volcanic-sedimentary sequences (Bao et al, 2018).…”

“…The subduction polarity of the southern Tianshan Ocean has been hotly debated in recent years, including northward (Zhu et al, 2005;Gao et al, 2006;Li et al, 2018b), southward (Wang et al, 2012) and bi-directional subduction models (Huang H et al, 2013;Zhao et al, 2015;Wang et al, 2016). Previous studies have demonstrated that widespread Late Paleozoic magmatic rocks in the Wusun Mountain, Awulale Mountain and the southern margins of the YB were related to the northward subduction of the southern Tianshan Ocean (Zhu et al, 2009;Li Y J et al, 2017).…”

Tianshan Orogen along the Silk Road (Volume 3): Orogen links, geochemistry, geochronology, mineral deposits, and environments

“…The mafic end‐member rocks indicate a mantle source, whereas silicic end‐member rocks are A‐type granites, formed by partial melting of the thinned lithosphere crust triggered by mafic magma upwelling. Y. Li et al ( ) studied the tectonic configuration of Carboniferous rocks in the Yining Massif of West Tianshan. They concluded that the Early Carboniferous volcano‐sedimentary rocks formed in a fore‐arc/back‐arc setting, similar to that of present‐day Japanese island arc, whereas the Late Carboniferous bimodal volcanic rocks and sediments formed in a continental rift setting after the Junggar‐Tarim collision.…”