Early Palaeozoic accretionary tectonics of West Kunlun Orogen: Insights from Datong granitoids, mafic–ultramafic complexes, and Silurian–Devonian sandstones, Xinjiang, NW China

Abstract

The Datong area is located in the western part of the Western Kunlun Orogen (WKO), occupying a key area of the Tethyan domain. Our new SHRIMP U–Pb zircon ages from the Datong area provide new information about the Palaeozoic evolution of the Western Kunlun Orogen. A 473.0 ± 2.8 Ma granite with 493.6 ± 4.8 Ma inherited zircons from the Kusilafu extrusive rocks is interpretation as an A‐type granite formed in a fore‐arc tectonic setting. The 485.5 ± 1.9 Ma granitoid of the Datongdong pluton combined with the 452.7 ± 7 Ma granitoid of the Datong pluton indicate that the Datong pluton is an intra‐oceanic arc complex formed by the southern subduction of the Proto‐Tethyan ocean crust. Zircons from gabbros of the Datong mafic–ultramafic complex have a 499.2 ± 2.1 Ma U–Pb crystallization age. Combined with its complicated whole‐rock geochemistry, we propose that there may have existed a Datong seamount in the early Palaeozoic. The detrital zircon results of Silurian–Devonian sandstones reveal that the Late Silurian sandstones have the characteristic zircons both from the Tarim Block and Datong Arc, suggesting that the Datong arc collided with the Tarim Block in the Late Silurian. The tectonic history of the WKO was characterized by a southern subduction of Proto‐Tethys terminated in the Late Silurian.

Muztaghata Dome Miocene Eclogite Facies Metamorphism: A Record of Lower Crustal Evolution of the NE Pamir

“…The Northern Pamir represents the Late Paleozoic to Triassic southern active margin of Asia. It is composed of two Asian affinity accretionary mélange terranes (the Kunlun terrane in the north and the Karakul-Mazar terrane in the south) with Early Paleozoic to Triassic arc type plutons (Figure 1a; Burtman & Molnar, 1993;Jiang et al, 2013;Li et al, 2018;Pan, 1994;Schwab et al, 2004;Xiao et al, 2005). The Late Paleozoic Kunlun suture zone defines the boundary between the Kunlun terrane and the Karakul-Mazar terrane in the south (Figure 1a).…”

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

“…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.…”

Post-collisional magmatism associated with the final closure of the Rushan-Pshart Meso-Tethys Ocean in Pamir, Tajikistan: Inference from Cretaceous igneous rocks of the Pshart accretionary complex

“…To the east and west, it is bounded by the transpressional Karakoram (dextral) and Darvaz (sinistral) faults respectively (Figure 1) (Burtman and Molnar, 1993;Robinson, 2009). The Northern Pamir is a part of the Kunlun Orogen that developed in response to subduction-accretion processes and the consumption of the Tethyan Oceans (Xiao et al, 2002;Robinson et al, 2012;Robinson, 2015;Li Y et al, 2018;Imrecke et al, 2019;Chen et al, 2021). Widespread intermediate granitoids of Triassic age (230-210 Ma) extensively intrude into the meta-sedimentary and meta-igneous mélange of the Karakul-Mazar accretionary complex (Schwab et al, 2004;Robinson et al, 2007).…”

“…In the Tibetan Plateau, Cretaceous magmatism with high a flux event occurring 110 Ma is widely distributed in the Lhasa terrane, which is interpreted to have formed in response to the near-flat northward subduction of the Neo-Tethys oceanic lithosphere (Zhang et al, 2010;Zhang K.-J. et al, 2012;Kang et al, 2014;Zheng et al, 2019), southward subduction of the Bangong-Nujiang Ocean, or a combination of both (Du et al, 2011;Zhu et al, 2013;Li Y et al, 2018;Ma et al, 2020). Jurassic arc-related granitoids of 198-170 Ma have been reported from the southern edge of the Pshart complex (Schwab et al, 2004;Chapman et al, 2018b), which are identical to the arc-related granitoids (185-170 Ma) of the Amdo region (Guynn et al, 2006).…”