Rapid cold slab subduction of the Paleo-Tethys: Insights from lawsonite-bearing blueschist in the Changning–Menglian orogenic belt, southeastern Tibetan Plateau

Petrogenesis of Early Carboniferous Ultramafic–Mafic Volcanic Rocks in the Southern Changning–Menglian Belt, Southeastern Tibetan Plateau: Implications for the Evolution of the Paleo‐Tethyan Ocean

“…1b) suggest that this area records the subduction of the oceanic Paleo-Tethyan Plate beneath the Lanping-Simao Block (e.g., Metcalfe, 2002Metcalfe, , 2013Jian et al, 2009a, b). The Paleo-Tethyan Ocean is thought to have opened during the Middle Devonian before widening into the main Paleo-Tethyan Ocean basin; this was followed by the initial onset of east-directed subduction (in the current orientation) during the earliest Permian (Metcalfe, 2002(Metcalfe, , 2013Ueno, 2003;Wang et al, 2019Wang et al, , 2020. Paleomagnetic data indicate the presence of significant differences in paleolatitude between the Baoshan and Simao blocks, providing evidence of the presence of a very large Changning-Menglian Ocean during the late Paleozoic (Li et al, 2004).…”

“…The ophiolitic mé lange contains peridotite, pyroxenite, gabbro, dolerite, basalt, and radiolarian chert units that yield dates that cluster between the Devonian and Permian (Feng, 2002;Jian et al, 2009a;Li et al, 2012;Metcalfe, 2013). Analysis of the blueschist and eclogite units within the belt indicates that this area underwent HP metamorphism at 248-240 Ma (Fan et al, 2015;Wang et al, 2020) and 229 Ma (Sun et al, 2018). The west-to-east spatial distribution of ophiolitic mé lange units, LT/HP metamorphic complexes, and subduction-related arc volcanic rocks (Fig.…”

“…Blocks in (a) are as follows: 1-Jinshajiang; 2-Ailaoshan; 3-Song Ma; 4-Longmu Co-Shuanghu; 5-Changning-Menglian; 6-Chiang Mai-Inthanon; 7-Bonggong-Nujiang; 8-Indus-Yalun-Zangbo; SM-LP = Lanping-Simao Block. Data for individual units in (b) are as follows: the Ganlongtang gabbro (Duan et al, 2006), Laochang OIB (Chen et al, 2010;Li et al, 2015), Damoguanfang supra-subduction zone (SSZ)-type ophiolite (Jian et al, 2009b), Mengku eclogite (Sun et al, 2018), Banpo plutonic arc (Jian et al, 2009a;Li et al, 2012), Suyi blueschist (Fan et al, 2015), Xinzhai blueschist (Wang et al, 2020), Yakou ophiolite (Zhai et al, 2019), and granitic Lincang batholith (Peng et al, 2008(Peng et al, , 2013Cong et al, 2020).…”

“…The Changning-Menglian Belt contains abundant late Paleozoic ophiolite mé lange and Triassic high-pressure metamorphic blueschist and eclogite units (Fan et al, 2015;Li et al, 2017;Wang et al, 2019Wang et al, , 2020. The ophiolitic mé lange contains peridotite, pyroxenite, gabbro, dolerite, basalt, and radiolarian chert units that yield dates that cluster between the Devonian and Permian (Feng, 2002;Jian et al, 2009a;Li et al, 2012;Metcalfe, 2013).…”

“…The Changning-Menglian Belt within the southeastern Tibetan Plateau represents the main Paleo-Tethyan suture zone within the SW Yunnan area (Ueno, 2003;Yang et al, 2014). This belt contains ophiolite mé langes (e.g., Feng, 2002; Metcalfe, 2008), arc-related volcanics (e.g., Jian et al, 2009a, b;Zhai et al, 2016), and low-temperature/high-pressure (LT/HP) rocks (e.g., Fan et al, 2015;Wang et al, 2019Wang et al, , 2020, all of which represent the evolution of the Paleo-Tethyan tectonic regime from rift-drift and seafloor spreading to the initiation of subduction and final closure (i.e., the majority of a Wilson cycle).The different types of magmatic rocks in ophiolites are formed in distinct tectonic settings within oceanic environments and surrounding areas, and thus they record…”