Petrogensis and tectonic setting of the Yemaquan granite from the iron‐polymetallic ore area of Qimantag, Eastern Kunlun Mountains, Qinghai–Tibet Plateau

Abstract

Being a part of the Paleo-Tethys Ocean, closing of the Buqingshan-Anyemaqen oceanic basin left a rich geologic record in the East Kunlun Orogenic Belt. The genesis and tectonic setting of the granites including quartz monzodiorite, granodiorite and mozogranite is discussed in light of the geochemical and U-Pb chronological data obtained. U-Pb dating studies on zircon from the quartz monzodiorite and monzogranite of the research area yielded ages of 220.11 AE 0.49 Ma ((Mean Square Weighted Deviates) MSWD = 0.046) and 223.33 AE 0.54 Ma (MSWD = 0.14), respectively, by Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) method. According to sedimentological and structural investigations, the Paleo-Tethys Ocean in the Qimantag region began to close at about 235 Ma, and completely disapperared at about 220 Ma. The three types of granites in this study are considered to intrude the syn-to post-collisional stages. The quartz monzodiorite and granodiorite belong to the I-type granite whereas the monzogranite is of the S-type granite. These two types of granites were formed by different ways of partial melting: first, partial melting of the lower crust took place as a result of asthenosphere upwelling triggered by break-up of the leading edge or tearing of the descending oceanic slab. Subsequently partial melting of the middle-lower crust was caused by the underplating of basaltic magma formed by partial melting of the mantle wedge fluxed by fluids liberated by the oceanic slab dehydration. The magma responsible for the formation of S-type granites appears to have originated from partial melting of the upper crustal material at a shallower level with a clear signature of continental crust. K E Y W O R D S Eastern Kunlun Mountains, Granitoid tectonic setting, petrogenesis, Qinghai-Tibet plateau, Tethys Ocean

“Scissors‐type” closure of the A'nyemaqen Ocean: Geochronological and geochemical constraints of Late Permian–Triassic granitoids in the East Kunlun Orogen

“…The EKO was previously considered to have undergone a complex and unique tectono-magmatic evolution, experiencing many transformations from subductions to subsequent continent-continent collision (Chen et al, 2016;Xu et al, 2011Xu et al, , 2012. During the Late Palaeozoic-Early Mesozoic, the EKO was linked to the A'nyemaqen Ocean and subsequent continental collision occurred (Mo et al, 2007), and numerous rocks that were generated during the tectonic-magmatic events are widely distributed in this region (Ren et al, 2016;Wang et al, 2018;Xin et al, 2019;Zhang, Mo, et al, 2017a;Zhao et al, 2020). The existence of an A'nyemaqen Ocean is supported by the Haerguole ophiolotes (LA-ICP-MS U-Pb age of zircons from gabbros, 332.8 ± 3.1 Ma; Liu et al, 2011) and the Derni ophiolites (whole rock 40Ar-39Ar age of basalts, 345.3 ± 7.9 Ma; SHRIMP U-Pb age of zircons from basalts, 308.0 ± 4.9 Ma; Yang et al, 2009).…”

“…The rocks associated with subduction and collision in the Middle- et al, 2008), and Yemaquan monzogranite (223.3 Ma;Zhang, Mo, et al, 2017a). Furthermore, the regional angular unconformity between the Upper Triassic Babaoshan Formation and underlying strata indicates the main collision events in the late stage of Middle Triassic-the early stage of Late Triassic (Li et al, 2012).…”

“…Meanwhile, the E-EKO has entered the collision stage in the Early-Middle Triassic. In the Middle-Late Triassic (226-215 Ma), unlike the post-collisional setting in the E-EKO, the magmatic rocks in the W-EKO, such as the Lalingzaohuo porphyritic granite (226.9 Ma; Wang, Chen, et al, 2014a) and Yemaquan granites (220.1-223.3 Ma;Zhang, Mo, et al, 2017a), would be related to collisional setting. After…”

Geochronology and geochemistry of the Late Devonian–Early Carboniferous volcanic rocks in Aksu River area, western end of the East Kunlun Orogen

“…B. Gao et al (); (39) Y. B. Gao et al (); (40) A. K. Zhang et al (); (41) Song et al (); (42) Guo, Xiao, Gao, Dong, and Xi (); (43) Zhao et al (); (44) Zhao et al (); (45) Zhao et al (); (46) Zhao et al (); (47) X. F. Gao et al (); (48) J. T. Wang (); (49) G. C. Chen, Pei, Li, Li, Pei, Liu, et al () [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…B. Gao et al (2014); (40) A. K. Zhang et al (2016); (41) Song et al (2016); (42) Guo, Xiao, Gao, Dong, and Xi (2010); (43) Zhao et al (2008); (44) Zhao et al (2008); (45) Zhao et al (2008); (46) Zhao et al (2008); (47) X. F. Gao et al (2010); (48) J. T. Wang (2017); (49) G. C. Chen, Pei, Li, Li, Pei, Liu, et al (2013b) [Colour figure can be viewed at wileyonlinelibrary.com] that the final elimination of the Paleo-Kunlun Ocean occurred at 400-375 Ma. As for the timing of the Paleo-Tethys-related Ocean opening: (a) Yang et al (2004) argued that the A'nyemaqen Ocean, which is a branch of Paleo-Tethys Ocean, opened in the Late Carboniferous based on an investigation of basalts.…”