Zircon U–Pb geochronology, Hf isotopes, and whole‐rock geochemistry of Hongshuihe Early to Middle Triassic quartz diorites and granites in the Eastern Kunlun Orogen, NW China: Implication for petrogenesis and geodynamics

Abstract

The Hongshuihe area of Eastern Kunlun Orogen is well‐known for the BIF‐type deposits. Some widespread intrusive rocks in the northern Hongshuihe area were previously thought to be emplaced in the Hercynian. This article presents LA‐ICP‐MS zircon U–Pb ages, with LA‐MC‐ICP‐MS in situ Hf isotopes and major and trace element data for quartz diorites and granites of the Hongshuihe pluton. Two samples from the Hongshuihe quartz diorite and granite yielded a weighted mean zircon U–Pb age of 244 ± 2 Ma (Anisian) and 246 ± 1 Ma (Olenekian), respectively. The Hongshuihe subalkaline quartz diorite is metaluminous with the alumina saturation index values of 0.93–1.00, and high SiO2 contents of 59.67–65.51 wt.%, low Y values of 11.1–16.7 ppm, and low HREE (Yb = 1.08–1.83 ppm) that collectively suggest high‐SiO2 adakite‐like rocks. The Hongshuihe granites have slightly high alkali contents of 7.04–8.12 wt.%, alumina saturation index values of 1.01–1.03, low (Zr + Nb + Ce + Y) contents of 315.30–455.50 ppm, and high Fe2O3T/MgO ratios of 4.03–5.16, indicating fractionated I‐type normal island arc magma. The zircon εHf(t) values from −4.0 to −1.1 for the Hongshuihe quartz diorite sample and values from −2.4 to +1.7 for the granite sample correspond to partial melting of Mesoproterozoic thickened lower crust and partial melting of juvenile mantle‐derived mafic lower crust, respectively. We conclude that during the Early–Middle Triassic, the Eastern Kunlun area underwent a tectonic setting of the northward subduction of the Palaeo‐Tethys oceanic slabs.

Geochemistry, geochronology, and Hf isotope of diorites in the Marzheng area: Implications for the Early Palaeozoic tectonic evolution of the East Kunlun Orogenic Belt

“…Moreover, there are Early Palaeozoic (ca. 555–420 Ma) subduction‐related granodiorite and diorite, and a battery of Triassic post‐collisional plutons are widely exposed in the South Kunlun Belt (Chen et al, 2018; Dong, He, et al, 2018; Li et al, 2007, 2020; Li, Huang, Luo, Dong, & Mo, 2015; Song et al, 2020).…”

Petrogenesis and tectonic implications of the quartz diorites and mafic microgranular enclaves in the Asiha gold ore deposit in the East Kunlun orogenic belt: Evidence from zircon U–Pb dating, geochemistry, and Sr–Nd–Hf isotopes

“…The EKOB in the Qinghai‐Tibetan Plateau is considered to undergo multi‐stages of tectonic‐magmatic evolution (Y. X. Chen, Pei, Li, Li, Liu, & Wang, 2017; Y. P. Dong et al, 2018; Du et al, 2017; J. J. Kong, Niu, He, Zhang, & Shao, 2020; Z. C. Li, Pei, et al, 2017; Y. G. Liu et al, 2018, 2019; X. Xu et al, 2020; Z. W. Zhang et al, 2018; M. J. Zhang et al, 2021). The evolutionary history of the Palaeo‐Tethys within the EKOB has attracted considerable attention over the past decades (Y. P. Dong et al, 2018; Gao & Sun, 2021; Hu et al, 2016; Huang et al, 2014; J. J. Kong et al, 2020; H. L. Kong et al, 2021; Y. Y. Liang, Xia, Ma, Zhao, & Guo, 2020; Richards, 2015; Shao et al, 2017; Song et al, 2020; Tian et al, 2021; J. Y. Zhang, Ma, Xiong, & Liu, 2012; Zhao et al, 2019). However, the precise timing of the termination of the continental collision and the beginning of the post‐collision of Palaeo‐Tethys along the EKOB remains poorly constrained.…”

“…L. Kong et al, 2021;Y. Y. Liang, Xia, Ma, Zhao, & Guo, 2020;Richards, 2015;Shao et al, 2017;Song et al, 2020;Tian et al, 2021;Zhao et al, 2019).…”