地质与勘探2025，Vol.61Issue(4)：684-697,14.DOI:10.12134/j.dzykt.2025.04.002
哀牢山成矿带新元古代金成矿事件识别:来自大坪超大型金矿热液磷灰石U-Pb年代学的约束
Identification of the Neoproterozoic Gold Mineralization Event:Constraints from Hydrothermal Apatite U-Pb Geochronology of the Super-Large Daping Gold Deposit in the Ailaoshan Metallogenic Belt
摘要
Abstract
The Ailaoshan metallogenic belt has undergone the subduction and closure of the Proto-,Paleo-,and Neo-Tethyan Oceans as well as continental collisions.It hosts a series of large-to medium-sized gold deposits,which serves as a natural laboratory for studying multi-stage mineralization processes.The super-large Daping gold deposit at the southern margin of this belt has been conventionally considered to form during the Late Eocene.However,its ore-hosting rocks are Neoproterozoic diorites,which have sparked controversy over its metallogenic age and hindered further research on ore genesis and mineral exploration.This study employed optical microscopy,scanning electron microscopy(SEM),and laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)to identify and conduct in-situ dating of hydrothermal apatite.Three mineralization stages are identified:(1)an early stage of gray-white quartz with minor pyrite±magnetite veins;(2)a main stage of smoky-gray quartz with abundant sulfide veins;and(3)a late stage of quartz-carbonate veins.Within the early-stage and main-stage quartz-sulfide veins,two types of apatite are observed:one filling fractures in pyrite,and the other coexisting with magnetite or monazite.These apatite grains are coarse(100～500 μm)and commonly exhibit metasomatic textures.They display high Th/U ratios and total rare earth element(REE)contents(ΣREE=2830.58×10-6-4315.61×10-6),with light REE enrichment,heavy REE depletion,and pronounced positive Ce anomalies(δCe=1.19-1.51),all indicative of a hydrothermal origin.In-situ LA-ICP-MS U-Pb dating of 12 hydrothermal apatite grains yields a lower intercept age of 761±60 Ma(MSWD=0.76)on the Tera-Wasserburg concordia diagram.Combined with previous age data from the Daping deposit and surrounding mineralized diorites(766-773 Ma)as well as quartz fluid inclusion 40Ar-39Ar ages(765.5±7.0 Ma),the Daping gold deposit was inferred to be formed during the Neoproterozoic.These findings provide crucial theoretical insights and exploration guidance for regional gold prospecting in the Ailaoshan metallogenic belt.关键词
热液磷灰石/扫描电镜/LA-ICP-MS/U-Pb定年/大坪金矿/哀牢山成矿带Key words
hydrothermal apatite/scanning electron microscope/LA-ICP-MS/U-Pb dating/Daping gold deposit/Ailaoshan metallogenic belt分类
天文与地球科学引用本文复制引用
林淞,王永彬,吴继雯,康志宏,杨福斗,唐昆..哀牢山成矿带新元古代金成矿事件识别:来自大坪超大型金矿热液磷灰石U-Pb年代学的约束[J].地质与勘探,2025,61(4):684-697,14.基金项目
云南省基础研究计划项目-重点项目(编号:202201AS070004)资助. （编号:202201AS070004）
