产于桂北四堡期花岗岩体内外带的达亮铀-多金属矿床成矿特征

Metallogenic Characteristics of Daliang Uranium Polymetallic Deposit Produced in the Inside and Outside Zone of Sibao Granite,North Guangxi

达亮矿床位于与上覆丹洲群呈不整合接触的四堡群,桂北四堡期花岗岩体西南侧的岩体内外接触带中。这一时期地幔源区处于异常热诱发地壳深熔状态,随后的岩浆活动形成于岩石圈伸展-裂谷阶段,对应于当时全球罗迪尼亚超大陆发生的聚合与裂解强烈构造热事件。该矿床铀矿化类型既有硅化带-沥青铀矿型,又有绿泥石-沥青铀矿型和碱交代型。铀矿化经混合岩化和碱交代达到预富集,并具高铀含量背景,是华南唯一海西期的铀成矿。岩体边缘相富含电气石,云英岩、绢英岩中高温蚀变发育;绢英岩与铀矿化关系密切,云英岩局部有黄玉与铜、锡矿化关系密切。矿床蚀变分带存在"上酸性下碱性",多种矿化存在"上氧化,下还原;上富铀矿化;下多金属硫化物矿化"的规律。铀矿化大体属"中部-矿根相",铜、锡金属硫化物矿化为"顶盖相",是一个多矿种并具远景的综合矿床。

Daliang deposit is located in Sibao group which is in unconformable contact with the overlying Danzhou group and in the contact zone southwest of Sibao granite.Mantle source is unusually hot during this period inducing deep crustal melting.The subsequent magma activity formed in lithosphere stretching rift stage,corresponding to the global tectonic thermal event-Rodinia supercontinent aggregation and dissociation.The types of uranium mineralization include silicide-pitchblende type,chlorite-pitchblende type and alkali-metasomatic type.Uranium enriched through migmatization and alkali metasomatism with high uranium content,which is the only uranium mineralization in Hercynian period South China.There are tourmaline in the edge of the granite,and high temperature alteration developed in greisen and sericitolite.The sericitolite is related to the uranium mineralization and the greisen locally developed with topaz has a close relationship with copper and tin mineralization.The deposit has an alteration characteristic of"the upper acid and the lower alkalinity"and mineralization characteristic of"the upper oxidation and the lower reduction,the upper uranium mineralization and the lower polymetallic sulphide mineralization".Daliang uranium deposit is an integrated one with multi-minerals and prospective which has a characteristic of uranium in the central ore body root phase and metal sulfide mineralization(copper and tin)as a top cover.