Origin of the Late Permian gabbros and Middle Triassic granodiorites and their mafic microgranular enclaves from the Eastern Kunlun Orogen Belt: Implications for the subduction of the Palaeo‐Tethys Ocean and continent–continent collision

Abstract

The geodynamic evolution of the Eastern Kunlun Orogen Belt (EKOB) during the late Palaeozoic-Early Mesozoic remains controversial. Here, we present new zircon U-Pb, element geochemical, and Sr-Nd-Hf isotopic data for the Kaerqueka gabbros, granodiorites, and their mafic microgranular enclaves (MMEs) in the Qiman Tahg area of Qinghai Province (QTQP), western EKOB, with a view to constrain their petrogenesis and tectonic setting. New LA-ICP-MS zircon U-Pb ages indicate that the Kaerqueka gabbro, granodiorite, and its MMEs were emplaced at 257 ± 2, 244 ± 1, and 245-244 Ma, respectively. Based on our new ages and published data, three major episodes of magmatism (ca. 263-249, 247-240, and 237-211 Ma) during the Late Permian-Triassic are recognized in the EKOB. The gabbros are characterized by low SiO 2 concentrations and are potassic with high K 2 O contents and K 2 O/Na 2 O ratios. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) and have ( 87 Sr/ 86 Sr) i of 0.70737-0.70851, εNd (t) of −2.8 to −2.7 and εHf (t) of +0.7 to +2.9, indicating that the gabbros were derived from an enriched lithospheric mantle which was affected by slab-derived fluids or melts. The MMEs and host granodiorites are enriched in LREEs and depleted in high-field-strength elements and have ( 87 Sr/ 86 Sr) i of 0.71090-0.71129, εNd (t) of −6.58 to −5.21, and εHf (t) of −5.3 to −1.8. Indistinguishable crystallization age, trace element pattern and isotopic compositions between the MMEs and host granodiorites indicate that they are cogenetic and were dominantly originated from the partial melting of Mesoproterozoic juvenile mafic lower crust. Combined with our new results and published geological, geochronological, and geochemical data, we propose that the subduction of the Palaeo-Tethyan Ocean lasted from Late Permian to Early Triassic, and that the onset of the collision mostly occurred during the Middle Triassic in the EKOB.

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

“…W. Chen, Luo, Mo, Liu, & Ke, 2005; Y. J. Li et al, 2020;Shao et al, 2017;Xia et al, 2014Xia et al, , 2017Xin et al, 2019;Xiong et al, 2012;Yao et al, 2018;J. Y. Zhang, Yang, et al, 2017;Zhou et al, 2020).…”

“…Voluminous Permian to Late Triassic igneous rocks are widespread in the EKOB, which are interpreted to be associated with subduction and collision during the Palaeo‐Tethys evolution. The intermediate–acid rock types consist of granodiorite, quartz diorite, monzogranite, tonalite, and syenogranite (Y. P. Dong et al, 2018; Feng, Wang, Li, Ma, & Li, 2012; Huang et al, 2014; Yu et al, 2017), in which MMEs are abundant (G. C. Chen, Pei, Li, Li, Liu, Chen, et al, 2017; G. C. Chen, Pei, Li, Li, Liu, et al, 2018, G. C. Chen, Pei, Li, Li, Pei, et al, 2018; H. W. Chen, Luo, Mo, Liu, & Ke, 2005; Y. J. Li et al, 2020; R. B. Li, Pei, et al, 2018; Shao et al, 2017; Xia et al, 2014, 2017; Xia, Wang, Qing, Li, et al, 2015; Xin et al, 2019; Xiong et al, 2012; Yao et al, 2018; J. Y. Zhang, Yang, et al, 2017; Zhou et al, 2020). The EKOB is one of the most important Triassic polymetallic metallogenic belts in China (X. D. Chen, Li, et al, 2020; H. Wang, Feng, Li, & Li, 2018; Y.…”

Consistency between apatite and zircon petrochronology supports robustness of apatite in fingerprinting igneous processes in porphyry systems

“…The Proto-Tethys Ocean began to form and expand in the Early Cambrian(Feng et al, 2010;Yang et al, 1996), the subduction gradually weakened in the Silurian and began to transition to a collisional orogeny stage(Liu et al, 2013;Ren et al, 2009), and changed from a syn-collision compressional environment to a post-collision extensional environment in the Devonian(Meng et al, 2015;Qi et al, 2016;Zhao et al, 2008). The Paleo-Tethys Ocean was in a subduction stage during the Late Permian-Early Triassic(Yao et al, 2020), and entered collision and post-collision stages during the Middle-Late Triassic(Feng et al, 2012). The Middle-Late Triassic is a very important metallogenic period in the QMB(Gao et al, 2014;Wang et al, 2018;Zhang et al, 2010).…”