沉积与特提斯地质2026，Vol.46Issue(2)：436-448,13.DOI:10.19826/j.cnki.1009-3850.2026.04003
尼泊尔低喜马拉雅带Lakharpata群沉积时限与沉积环境限定:来自顶部凝灰岩的年代学和地球化学证据
Constraints on the depositional duration and environment of the Lakharpata Group,Nepal Lesser Himalaya:Evidence from chronology and geochemistry of the top tuff layers
摘要
Abstract
The Lakharpata Group,a sedimentary sequence exceeding 5 000 m in thickness,is exposed in the Nepal Lesser Himalayan belt and preserves a key record of Precambrian tectono-sedimentary evolution along the northern margin of the Indian continent.However,its precise depositional age and tectonic setting remain poorly constrained.This study presents zircon U-Pb ages and geochemical data from newly identified tuff interlayers at the top of the Aru Formation,the uppermost unit of the Lakharpata Group in the Tansen area of central Nepal.Dating results indicate a volcanic eruption age of 1 569 Ma.Integrating with previously published detrital zircon ages from the underlying quartzite units,the depositional age of the Lakharpata Group in the Nepal Lesser Himalayan belt is constrained to approximately 1 680～1 569 Ma,corresponding to the Late Paleoproterozoic to Early Mesoproterozoic,rather than the previously assumed Mesoproterozoic to Early Paleozoic age.Geochemical analyses reveal that the tuffaceous rocks originated from a high-K subalkaline rhyolitic magma source,characterized by enrichment in K2O,Al2O3,MgO,and CaO,and depletion in Na2O.Their trace element compositions show enrichments in Th,U,and LREEs,with pronounced depletions in Ba,Sr,and Eu.Chondrite-normalized REE patterns display a distinctive right-inclined"V"-shape,implying an intraplate volcanic setting.Combined with sedimentary facies analysis,the Lakharpata Group is interpreted to have been deposited in a passive continental margin basin during the breakup of the Columbia supercontinent.关键词
锆石U-Pb年龄/凝灰岩/沉积环境/Lakharpata群/低喜马拉雅带Key words
zircon U-Pb age/tuff/depositional environment/Lakharpata Group/Lesser Himalayan belt分类
天文与地球科学引用本文复制引用
施美凤,杨平,卫红伟,何磊,王正和,李再会,杜佰伟..尼泊尔低喜马拉雅带Lakharpata群沉积时限与沉积环境限定:来自顶部凝灰岩的年代学和地球化学证据[J].沉积与特提斯地质,2026,46(2):436-448,13.基金项目
国家重点研发计划课题"高纯石英原料矿床成矿规律与成矿预测"(2024YFC2910102) （2024YFC2910102）
商务部援外项目"援尼泊尔油气资源调查"(CGSA001) （CGSA001）
中国地质调查局"东南亚和南亚地区国际合作地质调查"项目(DD2026080102) （DD2026080102）
