The continental subduction in the evolution of central qiangtang mélange belt and its tectonic significance

Sedimentary Evolution and Provenance of the late Permian‐middle Triassic Raggyorcaka Deposits in North Qiangtang (Tibet, Western China): Evidence for a Forearc Basin of the Longmu Co‐Shuanghu Tethys Ocean

“…This inference is based on the Paleozoic-early Triassic ophiolite suites discovered within the hanging wall of the detachment fault Zhu et al, 2006;Wang, Pan, et al, 2008;Wu et al, 2010;Zhang et al, 2017;Fan et al, 2017) and the distinct stratigraphy and biota in the two blocks Li et al, 1995;Liu et al, 2002;Metcalfe, 2013). The in situ suture model is also supported by the observation that the CQMB features multistage penetrative deformations associated with oceanic subduction and the ensuing late Triassic-early Jurassic continental collision between the NQB and SQB Li et al, 2019;Wang et al, 2018;Zhao et al, 2015). In the past, the NQB was thought to be derived from the Cathaysian realm .…”

“…Geological mapping has shown that the CQMB is a typical "block in matrix" mélange (Kapp et al, , 2003Li et al, 2019;Liang et al, 2012Liang et al, , 2017Pullen et al, 2008Pullen et al, , 2011Wang et al, 2009; Wang et al, Liang et al, 2015). The locations of sedimentary structures, two stratigraphic sections, and the sandstone samples are indicated on the rose diagram.…”

“…C. Zhang, Shen, et al, 2012), middle-late Triassic abyssal sedimentary rocks (Deng et al, 1996;Li et al, 1997), and Ordovician quartzite and limestone slices (Dong et al, 2011;. The CQMB is characterized by a low-grade metamorphism and ductile deformation in the form of early penetrative E-W shearing fabrics and later N-S compressional structures Li et al, 2019;Wang et al, 2018). The CQMB is separated by an angular unconformity from the overlying upper Triassic neritic carbonate and clastic rocks of the Wanghuling Formation ( Figure 1a) (Ji et al, 2010;.…”

“…C. Zhang, Shen, et al, 2012). The provenance of the CQMB has been verified to be predominantly from Gondwana to the south (Kapp et al, 2003;Pullen et al, 2008Pullen et al, , 2011, including the Paleozoic passive continental margin of the SQB and Paleo-Tethys Ocean Liang et al, 2012;Li et al, 2019;Zhao et al, 2014). The tectonic origin of the NQB, however, is still widely debated, that is, either from Gondwana or Cathaysian/Laurasian Pullen et al, 2011;Song et al, 2015Song et al, , 2017.…”

“…Two major hypotheses have been proposed to explain the tectonic origin of the CQMB: (1) The CQMB was an allochthonous complex that originated from the ~200 km southward underthrust of the Songpan‐Ganzi flysch/Paleozoic arc terrane beneath a unified Qiangtang block and was subsequently exhumed by extensional detachment faults in the late Triassic‐early Jurassic (Yin & Harrison, ; Kapp et al, ; Pullen et al, , ; Pullen & Kapp, ), and (2) the CQMB was an accretionary complex of an in situ suture attributed to the northward subduction of the Longmu Co‐Shuanghu Tethys Ocean beneath the NQB in the late Paleozoic‐middle Triassic (Li, ; Li et al, , , ; Li, Zhai, Dong, et al, ; Li, Zhai, Chen, et al, ; Li, Chen, et al, ; Li, Huang, et al, ; Liang et al, , ; Wang et al, , ; Zhang, Cai, et al, , Zhang, Zhang, et al, ; Zhai, Zhang, et al, ; Zhai, Jahn, et al, ; Zhai, Jahn, Wang, et al, , ; Zhang, Cai, et al, ; Zhang, Zhang, et al, ). The allochthonous complex model was the first model indicating that the high‐pressure and low‐temperature (HP‐LT) metamorphic rocks in the CQMB were exhumed from mantle depths by a crustal‐scale detachment fault, and this finding was later corroborated by structural mappings (Liang et al, ; Zhao et al, ).…”