湘南界牌岭锡多金属矿床萤石LA-ICP-MS微量元素地球化学特征及意义  

LA-ICP-MS trace element analysis of fluorite and implications in Jiepailing tinpolymetallic deposit from South of Hunan Province

作　　者：许若潮 龙训荣[1] 刘飚[2,3] 刘玉国 吴堑虹[2,3] 罗心雨[2,3] 蒋华 XU RuoChao;LONG XunRong;LIU Biao;LIU YuGuo;WU QianHong;LUO XinYu;JIANG Hua(Chengdu University of Technology,Chengdu 610059,Sichun,China;School of Geosciences and Info-Physics,Central South University,Changsha 410083,Hunan,China;MOE Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geologi-cal Environment Monitoring,Central South University,Changsha 410083,Hunan,China)

机构地区：[1]成都理工大学,四川成都610059 [2]中南大学地球科学与信息物理学院,湖南长沙410083 [3]中南大学有色金属成矿预测与地质环境监测教育部重点实验室,湖南长沙410083

出　　处：《矿床地质》2022年第1期158-173,共16页Mineral Deposits

基　　金：湖南省自然科学青年基金项目(编号:2021JJ40722);国家重点研发计划“钦杭成矿带湘南段铜锡多金属矿产深部探测技术示范”(编号:2018YFC0603902)联合资助。

摘　　要：湘南界牌岭矿床不仅是南岭地区发育的一个晚白垩世超大型锡多金属矿床,同时也是该区乃至中国重要的萤石产地,锡多金属矿及萤石的找矿勘查均具有重要前景。通过野外地质调查与岩石学研究,文章识别出多种类型的锡多金属与萤石矿化,并针对不同类型萤石开展原位LA-ICP-MS微量元素分析,研究表明:(1)矿体分为锡多金属矿体与萤石矿体2类,矿石类型主要有热液交代型、细脉型、云英岩型、角砾岩型;(2)锡多金属矿体分布在浅部花岗斑岩脉与深部铁锂云母花岗岩体的内外接触带,矿石矿物组合为锡石+黄铜矿+闪锌矿±方铅矿+石英±萤石;(3)萤石矿体分布范围更广,至少存在3期成矿:第一期为角砾状紫色萤石,粒径0.3~2.0 mm,w(ΣREE+Y)为(2.05~60.40)×10^(-6),稀土元素配分型式为平坦型,形成深部被花岗斑岩捕获携带至浅部,且花岗斑岩对萤石角砾进行了热液交代;第二期为皮壳状萤石,以无色与浅紫色为主,粒径0.05~0.50 mm,伴随有强烈的黄玉化,w(ΣREE+Y)为(26.9~93.8)×10^(-6),稀土元素配分型式更加富集HREE,为岩浆热液交代石磴子组灰岩形成;第三期为细脉状无色萤石,穿切第二期萤石,粒径0.5~2.0 mm,w(ΣREE+Y)为(3.94~37.5)×10^(-6),稀土元素配分型式为左倾型。从早期到晚期,萤石w(ΣREE+Y)呈先升高后降低的趋势,轻、重稀土元素分馏程度不断增高,稀土元素配分型式由平坦型变为左倾型,但是Y/Ho比值变化较小,显示了同源特征。此外,前2期萤石稀土元素配分型式与浅部花岗斑岩的全岩稀土元素配分型式相似,指示二者具有成因关系。综合研究认为,界牌岭多期次锡多金属与萤石成矿均与晚白垩世岩浆活动有关,且深部铁锂云母花岗岩内外接触带可能存在更多的隐伏矿体,未来的找矿勘查工作应重点关注此区域。The Jiepailing deposit, located at the central of Nanling metallogenic belt, is a giant Late Cretaceous Sn polymetallic ore and a significantly fluorite producing area in China. Various types of Sn polymetallic and fluorite ores were identified by field geological investigation and microscopic observation. Different types of fluorite grains was carried out by in-situ LA-ICP-MS for the trace element analysis. The research results show that:(1)The orebodies are divided into two types: Sn polymetallic and fluorite orebodies;the ore types are composed of hydrothermal metasomatic, veinlet, greisen, and breccia.(2) Sn polymetallic orebodies are distributed in the contact zone between shallow granite porphyry veins and deep zinnwaldite granite with a mineral assemblage of cassiterite + chalcopyrite + sphalerite±galena+quartz±fluorite.(3) Fluorite orebodies are widely distributed in the deposit, and three stages veins are identified: the stage Ⅰ ores consists of the angular purple fluorite with a particle size of 0.3~2.0 mm and the w(ΣREE+Y) content of fluorite is(2.05~60.48)×10^(-6) with a flat REE pattern;it was formed in the deep early, which is captured and carried to the shallow part by granite porphyry;in addition, the rim of fluorite breccia is metasomatized by hydrothermal fluid of granitic porphyry;the stage Ⅱ ores is composed of near bedded fluorite and dominated by crusty colorless-light purple fluorite with a size of 0.05~0.50 mm and strong topazization;the w(ΣREE+Y) content of fluorite is(26.9~93.8)×10^(-6), and the REE pattern is also flat with weak HREE-enrichment, which is the result of magmatic hydrothermal fluids metasomatism of the Shidengzi Formation;the stage Ⅲ ores is characterized by the veinlets colorless fluorite and cut though the stage Ⅱ fluorite orebodies;the particle size of fluorite is 0.5~2.0 mm, the w(ΣREE+Y) content of fluorite is(3.94~37.50)×10^(-6), and the REE pattern is HREE-enriched. From early stage to late stage, the w(ΣREE + Y) content of fluorite showed a trend f

关 键 词：地球化学 锡多金属 萤石 晚白垩世 稀土元素 界牌岭 南岭地区 

分 类 号：P618.44[天文地球—矿床学]