Shoshonitic- and adakitic magmatism of the Early Paleozoic age in the Western Kunlun orogenic belt, NW China: Implications for the early evolution of the northwestern Tibetan plateau

Accretionary orogenesis triggered by collision across continent distance: Evidence from the Proto‐Tethyan West Kunlun, China

“…Zircons extracted from the Akedala pluton also provide a positive test to crustal thickening in Cycle III. The thick lower crust‐derived adakitic nature for the 470–452 Ma Datong (most of the samples) and Akedala plutons (Li et al, 2019; Liao et al, 2010; Wang et al, 2017; Xu et al, 2021; Zhu et al, 2018) lends additionally petrological supports for the Cycle III thickening event. West Kunlun crust abruptly gained a thickness >70 km (430 Ma) and lost its thickness at Early Devonian (Cycle IV).…”

“…La/Yb‐based crustal thickness estimates show episodic crustal thickening and thinning processes, which were divided into four cycles (I to IV). These crustal thickening and thinning events are supported by accompanying geological evidences including A‐type or bimodal rocks (~523 Ma Taxkorgan rocks, ~478 Ma Kusilafu pluton and ~405 Ma North Kudi pluton; Gao et al, 2013; Li et al, 2019; Xiao et al, 2005; Yuan et al, 2002), adakitic rocks (~513 Ma Datongdong and Yirba plutons, 470–452 Ma Datong and Akedala plutons and 430 Ma Buya pluton; Hu, Guo, et al, 2017; Li et al, 2019; Liao et al, 2010; Liu et al, 2014; Wang et al, 2017; Xu et al, 2021; Ye et al, 2008; Yin et al, 2020; Zhu et al, 2018), ~520 Ma northward migration of arc magmatism (Yin et al, 2020) and ~440 Ma amphibolite‐facies metamorphism (Zhang, Zou, et al, 2019). Crustal thickness estimates from magmatic zircons are in agreement with those from the whole‐rock La/Yb method.…”

“…Admittedly, Cycle III accretionary orogenesis in West Kunlun could be a rather local event. Co-existence of subducted oceanic crust-and thick lower crust-derived adakites (e.g.Datong pluton;Li et al, 2019;Liao et al, 2010;Wang et al, 2017;Zhu et al, 2018) together with a sharp shift in zircon Hf isotopic compositions toward positive values at 460 Ma are somewhat consistent with the subduction of oceanic ridges or slab breakoff, which deserves further study.5 | IMPLIC ATIONSSignificant accretionary orogeneses at 520-450 Ma were identified before the 450-400 Ma collisional orogenesis in Proto-Tethyan West Kunlun. In West Kunlun, 520-480 Ma accretionary orogenesiswas a geodynamical response to the final collision among blocks within Gondwana.…”

“…Key magmatic rocks are specially marked. These rocks were compiled from (Cui et al, 2006; Cui, Wang, Bian, Zhu, et al, 2007; Cui, Wang, Bian, Luo, et al, 2007; Gao et al, 2013; Hu, 2018; Hu et al, 2016; Hu, Wang, et al, 2017; Hu, Guo, et al, 2017; Jia et al, 2013; Li et al, 2019; Liao et al, 2010; Liu et al, 2014, 2016, 2019; Wang et al, 2013, 2017; Xiao et al, 2005; Xu et al, 2021; Ye et al, 2008; Yin et al, 2020; Yuan et al, 2002; Zhang et al, 2007; Zhang, He, et al, 2016; Zhang, Liu, et al, 2016; Zhang et al, 2018a; Zhang, Wu, Chen, et al, 2019; Zhang, Wu, Li, et al, 2019; Zheng et al, 2013; Zhu et al, 2016, 2018; Zhuan et al, 2018). Please see Table S2 for more details.…”

“…The collision process was well documented by the ~450 Ma highto ultrahigh-pressure metamorphism (e.g. Li et al, 2018;Zhang et al, 2017;Zhou et al, 2000). However, Proto-Tethyan orogenic processes prior to the late Ordovician collision are not studied in sufficient detail.…”