New Insights into the Late Triassic Nadigangri Formation of Northern Qiangtang, Tibet, China: Constraints from U-Pb Ages and Hf Isotopes of Detrital and Magmatic Zircons
  • 【摘要】

    We report here U-Pb age and in situ Hf isotopic results for detrital and magmatic zircons from one conglomerate and four tuffite samples from the Late Triassic Nadigangri Formation across the North Qi... 展开>>We report here U-Pb age and in situ Hf isotopic results for detrital and magmatic zircons from one conglomerate and four tuffite samples from the Late Triassic Nadigangri Formation across the North Qiangtang depression,Tibet.Coupled with previously published data in the region,this paper proposes new insights into the geochronological framework for the Nadigangri Formation.The deposition ages of tuffite from top to bottom in the Woruo Mountain,Quem Co and Dongqu River,are 203 Ma,226 Ma,221.5 Ma and 221.1 Ma,respectively.The detrital zircons yield a younger cluster of ages of 201.5-225 Ma from the conglomerate of the Quem Co Formation.The Late Triassic Nadigangri Formation defines a temporal range approximately between 201 and 225 Ma (Norian-Rhaetian),including three predominant groups of 220-225 Ma,210-217 Ma and 201-205 Ma,which correspond with the three main rifting episodes of initial rifting,further rifting and final rifting.Positive εHf(t) value and low model ages in younger detrital zircons suggests a juvenile character.However,the Hf isotopes of magmatic zircons display the presence of reworked ancient crust with 1.1-1.8 Ga.These results provide strong constraints not only on the temporal range of the Late Triassic Nadigangri Formation,but also on the onset of the Qiangtang Mesozoic rift basin. 收起<<

  • 【作者】

  • 【作者单位】

    Chinese Academy of Geological Sciences/Key Laboratory for Sedimentary Basin and Oil and Gas Resources/Institute of Mud Logging Technology and Engineering

  • 【刊期】

    地质学报(英文版) SCI 2018年4期

  • 【关键词】

    U-Pb ages  Hf isotope  Nadigangri Formation  Late Triassic  Qiangtang 

  • 【基金项目】

    We thank Professor Zhaochu Hu for helping with the LA-ICP-MS U-Pb and Hf analyses.We would also like to express our appreciation to all members of the project team from the Chengdu Center of the Chinese Geological Survey,for their support and assistance during the fieldwork stage of the study.This s a project program under China Geological Survey