浙江省大洲火山岩盆地深部铀成矿模式研究

Study on Depth Uranium Metallogenic Model in Dazhou Volcanic Basin of Zhejiang Province

为了加快浙江西部深部和外围铀矿找矿,拓展新的找矿方向,以大洲地区重点铀矿床为对象,深入研究了其成矿规律和控矿因素。区内铀矿体主体形态为层状,沿断裂构造有少量的脉状矿体,矿石矿物主要为沥青铀矿,少量为铀石,呈显微浸染状和团块状,铀矿石年龄分布在110.0~67.1 Ma,铀成矿具多阶段性。铀矿床(体)明显受构造、地层、热液蚀变联合控制,多期次、不同规模的断裂构造控制了铀矿床(体),多期次火山喷发形成的层状流纹岩为铀成矿准备了围岩条件,热液蚀变多样,成矿期蚀变主要有赤铁矿化和萤石化,其中水云母化蚀变的"绿色层"与铀矿体赋存关系密切,成矿热液主要来源于深部下地壳。在此基础上构建了三阶段深部铀成矿模式,指出在深部找矿的重点为(1)九里坪组第四、第五层流纹岩层控制的层状矿体,(2)九里坪组层状矿体之下的深部脉状矿体,这些认识可供本区铀矿找矿新突破参考。

In order to speed the progress of peripheral and the depth of uranium prediction up in the western Zhejiang Province,and to expand the prospecting direction for uranium resources,the significant uranium deposit in Dazhou area is taken on as the object of the research to study detailedly the metallogenic regularity and ore-control factors.The main U-orebody form is layered,and there is little veinlike U-orebody which distribute along the structure.The main ore mineral is uraninite that is Micro disseminated or crumby structure,and the little ore mineral is coffinite.The age of uranium oreis of multi-stage from 110.0 Ma to 67.1 Ma.It is found that uranium deposit is obviously controlled by the structure,strata and hydrothermal alteration,and the location of uranium deposit is controlled by the multi-stage and different scales structures.The layered rhyolite which result from the multi-stage vulcanian eruption is favorable metallogenic wall rock.The type of hydrothermal alteration is various,hematization and fluoritization mainly exist in metallogenic epoch.There is close relationship between‘Green Layer’in alteration of hydromicazation and the position of uranium ore body.The ore-forming hydrothermal mainly comes from lower crust.The three-stage uranium metallogenic model in the deep is established based on these researches to point out the main exploration point:①The layered U-orebody is controlled by the fourth and fifth rhyolite strata in the Jiu liping group;②The depth of veinlike U-orebody which is under the Jiu liping group.The new breakthrough in uranium prospecting in research area is pointed out by all of this information.