Late Silurian to Late Triassic seamount/oceanic plateau series accretion in Jinshajiang subduction mélange, Central Tibet, SW China

Abstract

The timing of the initial opening and subduction of the Palaeotethyan Ocean is currently highly debated, in particular regarding the Jinshajiang Ocean in the central Tibetan Plateau. This study presents four well‐constrained U–Pb zircon ages (422.4 ± 6.1, 336.4 ± 7.4, 272.3 ± 2.8, and 255.8 ± 3.4 Ma) of mafic blocks in the Jinshajiang Suture. These mafic blocks have a chemical oceanic island basalt (OIB) affinity. These facts, together with previously published data (236 Ma OIBs), may be interpreted as a series of seamounts/oceanic plateaux varying from Late Silurian to Late Triassic, which were accreted early in the subduction–accretion process. An andesite from the Jinshajiang Suture with continental arc characteristics yielded a zircon U–Pb weighted average age of 385.2 ± 6.6 Ma, implying that the subduction initiation may have occurred at least in the Middle Devonian. Our work suggests a long‐lived continuous accretion, which also puts an earlier initial opening time than previously thought. Taking into account the above data and integrated with relevant published information, we favour a long‐lived accretionary process accompanied with seamounts/oceanic plateaux, which provides robust new evidence for subduction‐related continental growth in the central Tibetan Plateau.

Geochronology and petrogenesis of the early Silurian Zeluo mafic-ultramafic intrusion, eastern Tibet: implications for the tectonic setting and evolution of the eastern Proto-Tethys Ocean

“…Firstly, 439.3 ± 3.5 Ma continental flood basalts have been identified from the Jinshajiang suture zone on the western margin of the Yangtze plate, which are associated with an early continental rifting episode (Jian et al, 2009a;. Secondly, a ~422 ± 6.1 Ma mafic rock block with OIB characteristics, from the Jinshajiang suture zone, was interpreted to have formed in a tectonic setting that was undergoing a subduction accretion (Liu et al, 2019). This suggests that the Jinshajiang paleo-Tethys was most likely produced in a back-arc basin, which was the result of the subduction of the Proto-Tethys ocean (Wang et al, 2012).…”

“…Tethys, also known as the Tethys Sea or Tethys Ocean, was proposed in 1893 by the Austrian geologist Eduard Suess (Sengör, 1984), as a vast Mesozoic paleo-ocean that separated the Gondwana continent in the south, from the Angolan paleo-continent in the north. Much research has been devoted to geological studies of the East Tethys tectonic belt, mainly on the Tibetan Plateau, due to the importance of this extensive tectonic belt for understanding past plate reconstructions and geodynamics (Reid et al, 2005;Yan et al, 2005;Jian et al, 2008;Hu et al, 2009;Jian et al, 2009a;Roger et al, 2010;Wang et al, 2012;Zi et al, 2012;Hu et al, 2013;Hu et al, 2014;Wang et al, 2016a;Li et al, 2017;Zhao et al, 2017;Zhao et al, 2018;Liu et al, 2019;Xu et al, 2021). Based on a multidisciplinary dataset, four Tethyan ocean basins have been recognised in Asia (Metcalfe, 2021), the Proto-Tethys (Sinian-Silurian), Paleo-Tethys (Middle Devonian-Late Triassic), Meso-Tethys (Middle Permian-Late Cretaceous) and the Ceno-Tethys (Late Middle Triassic-Eocene).…”

Preface: Tectonics of China

“…Y. Liu et al () present four well‐constrained U–Pb zircon ages (422.4, 336.4, 272.3, and 255.8 Ma) of mafic blocks in the Jinshajiang Suture in the Central Tibetan Plateau. Based on the oceanic island basalt (OIB) affinity of these mafic rocks, they suggested a long‐lived accretionary process accompanied with seamounts/oceanic plateau along the Jinshajiang Suture, which provides robust new evidence for subduction‐related continental growth in the central Tibetan Plateau.…”

Polarity and Timing of the Deformation Along the Jinsha Suture Zone (Yushu Area, Northeastern Tibet)

“…In the recent years, several studies have focused on acquiring precise ages and geochemical data on the pre‐Cenozoic magmatic rocks that line the Western Jinsha suture between the North Qiangtang and Songpan‐Ganze terranes (Chen et al., 2005; Gu et al., 2013; Jin, 2006; G.‐M. Li et al., 2015; J. Li et al., 2012; B. Liu, Ma, Guo, Sun, et al., 2016; B. Liu, Ma, Guo, Xiong, et al., 2016; Y. Liu et al., 2010, 2014, 2021; Y. Liu, Tan, et al., 2019; Y. Liu, Xiao, et al., 2019; Tan et al., 2020; B. Z. Wang et al., 2008; Yang et al., 2012; Yong et al., 2011; H. Zhang et al., 2017; Zhao, Fu, et al., 2015; Zhao, Tan, et al., 2015).…”