“…Magmatic rocks are poorly exposed along the Paleo-Tethyan Ocean between the South China Craton and Indochina Block (Figure 1), and thus its subduction polarity has been controversial. Some studies suggested that the subduction was bidirectional (e.g., Zhong et al, 2013;Hou et al, 2017;Xia et al, 2019;Xu et al, 2019), whereas other studies argued that the subduction was unidirectional (e.g., Faure et al, 2014;Ngo et al, 2016;Yu et al, 2016;Gan et al, 2021;Li et al, 2021;Wang et al, 2021). The latter suggested that the southwestern margin of the South China Craton was a passive continental margin (Yan et al, 2019), and the Paleo-Tethyan Ocean may only undergo a subduction westward beneath the Indochina Block during the Late Permian-Early Triassic (Jian et al, 2009;Faure et al, 2014;Ngo et al, 2016;Li et al, 2021;Wang et al, 2021).…”