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Early Mesozoic Magmatism Within the Tibetan Plateau: Implications for the Paleo‐Tethyan Tectonic Evolution and Continental Amalgamation
Author(s) -
Li Shan,
Chung SunLin,
Hou Zengqian,
Chew David,
Wang Tao,
Wang Baodi,
Wang Yanbin
Publication year - 2019
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2019tc005546
Subject(s) - geology , tethys ocean , magmatism , paleontology , subduction , continental crust , plateau (mathematics) , continental collision , mesozoic , permian , continental arc , early triassic , tectonics , zircon , geochronology , oceanic crust , crust , earth science , structural basin , mathematical analysis , mathematics
Numerous early Mesozoic magmatic rocks within the Tibetan Plateau ultimately have a geodynamic controll caused by the Paleo‐Tethyan tectonic evolution and the assembly of Pangea. Based on their temporal variation and the timing of closure (235 ± 10 Ma) of the Paleo‐Tethys Ocean, they can be broadly divided into two groups by zircon U‐Pb geochronology: an Early to Middle Triassic (252–235 Ma) group and a Late Triassic to Early Jurassic (ca. 235–190 Ma) group. Early magmatic rocks are mainly found in the middle northern Tibetan Plateau, whereas late magmatic rocks are more widespread in the whole Tibetan Plateau. Nd and Hf isotope mapping suggests that the eastern segment of the Qiangtang is underlain by old (late Archean to early Paleoproterozoic) basement, while Southern Lhasa is underlain by juvenile lower crust, which yields Neoproterozoic to early Paleozoic model ages. Early Mesozoic tectonomagmatism was likely caused by episodic southward opening of multi‐Tethys oceans, punctuated by episodes of subduction and collision. The Middle to Late Permian tectonomagmatic history of Paleo‐Tethys was dominated by continental arc‐related systems. During the Early to Middle Triassic, the tectonomagmatic history was associated with the ongoing closure of the Paleo‐Tethys Ocean and a tectonic transition from subduction to collision. Late Triassic tectonomagmatism formed in a post‐collisional setting following the closure of the Paleo‐Tethys Ocean and the ultimate assembly of Pangea. Early Mesozoic magmatism within the Tibetan Plateau thus provides crucial information on the history of oceanic‐continental evolution and helps constrain the tectonic transition from subduction/accretion through to collision/postcollision for East Paleo‐Tethys.