An 850–820 Ma LIP dismembered during breakup of the Rodinia supercontinent and destroyed by Early Paleozoic continental subduction in the northern Tibetan Plateau, NW China
Neoproterozoic intraplate magmatism is widely distributed in NW China and generally thought to be related to the breakup of the Rodinia supercontinent. Here we report a fragmented Large Igneous Province (LIP) formed at 850–820 Ma in the northern margin of the Qaidam block, northern Tibetan Plateau (named herein as the “North Qaidam LIP”). The associated rocks have undergone various grades of metamorphism from greenschist to ultrahigh-pressure (UHP) eclogite facies, including the greenschist-facies Yingfeng dolerite dikes and basalts (846–821 Ma), the amphibolite- to HP granulite-facies Aolaoshan meta-volcanic sequence (protolith age of 832 Ma and metamorphic age of 439 Ma), and the North Qaidam UHP eclogites (protolith age of 847–828 Ma and metamorphic age of 440–420 Ma). Geochemical data reveal that they resemble present-day E-MORB/OIB and typical continental flood basalts. These features, together with high potential temperatures (Tp = 1434–1524 °C) for “primary” magmas, suggest that these basaltic rocks were most likely derived from a mantle plume source and were emplaced in a continental extensional environment.
Геолого-географический факультет
An 850–820 Ma LIP dismembered during breakup of the Rodinia supercontinent and destroyed by Early Paleozoic continental subduction in the northern Tibetan Plateau, NW China