Geochronological Evidence of Ordovician and Jurassic Magmatic Events in Nyainrong Microcontinent,Tibet
Lu Lu
Qian Cheng
Zhao Zhen
Wu Zhenhan
Liu Yushuang
Zhou Liang
Wang Yan
Abstract：In order to deepen our knowledge and understanding about the tectonic evolution of the Bangonghu-Nujiang suture zone(BNS),zircon U-Pb dating was conducted for granitic gneiss and granodioritic gneiss of Nyainrong microcontinent by LA-ICP-MS in this study.Results show two groups of average zircon U-Pb ages,with one of 453.7±2.5 Ma,and the other of 176.6±1.1 Ma and 178.04±0.8 Ma.40Ar-39Ar dating was conducted for biotite from granitic gneiss and muscovite from grano-dioritic gneiss in Nyainrong microcontinent.The 40Ar-39Ar plateau ages yield 161.8±1.1 Ma and 178.9±1.2 Ma,respectively, showing that the study area experienced the Late Ordovician and the Early Jurassic magmatic events.Combined with field con-dition and study results,it is suggested that the Ordovician magmatic event was related to the Early Paleozoic orogeny which could be caused by proto-Tethyan oceanic subduction along Gondwana continental margin,and the Jurassic magmatic event was related to the subduction and closure of the Bangong-Nujiang oceanic crust.
Keywords：Tibetan plateauNyainrong microcontinentzircon U-Pb age40 Ar-39Ar ageBangonghu-Nujiang suture zonege-ochronology
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 1110-1124 )