九龙嶂火山盆地铀矿成矿条件及找矿方向

九龙嶂火山盆地位于南岭成矿带安远热隆的西部,面积120余km2,盆地基底为加里东期至燕山期花岗岩和元古界至古生界沉积岩、变质岩,盖层为上侏罗统鸡笼嶂组火山岩系地层.盆地基底岩石碱交代蚀变明显,火山期后浅成-超浅成侵入岩浆活动频繁,火山构造与区域构造多处交接复合并形成派生构造,使盆地具有良好的、利于铀矿形成的"源-运-聚"条件.盆地西部半天塘至银坑山一带,火山构造发育,岩性复杂多变,热液蚀变较强烈,矿化信息丰富,是找矿方向和勘查重点所在.盆地西部银坑山铀矿点,受发育于流纹质熔结凝灰岩中的近SN向碎裂带控制,地表浅部矿化良好,具有岩浆热液体系的顶部矿化蚀变组合特征,深部有明显延伸的矿化显示,可作为九龙嶂火山盆地铀矿勘查的突破口.

Uranium metallogenic conditions and prospecting direction in Jiulongzhang volcanic basin

The Jiulongzhang volcanic basin with an area of about 120 km 2 is situated in the western part of Anyuan upwelling structure,Nanling uranium metallogenic belt.The basement of the basin consists of Caledonian-Yanshanian granites and Proterozoic-Paleozoic sedimentary and metamorphic rocks.The cover of the basin is composed of volcanic series of Jiulongzhang Formation,Upper Jurassic.Basement rocks experienced obvious alkaline metasomatism.Post-volcanic hypabyssal-superhypabyssal intrusive activities took place frequently.The multiple intersection and mergence of volcanic and regional structures led to the fomation of subsidiary structures making the basin having favourable source-migration-concentration conditions for uranium ore-formation.The western part(Bantiantang-Yinkengshan area)is characterized by intense development of volcanic structures,complicated and heterogeneous lithology,strong hydrothermal alteration and a great amount of mineralization information being the main prospecting direction and exploration target.The Yinkengshan uranium occurrence in the west of the basin is controlled by SN-trending fractured zone in rhyolitic ignimbrite.Surface uranium mineralization shows features of top mineralization-alteration assemblage of magmatic-hydrothermal system and there exists message indicating the extension of uranium mineralization towards the deep.So,the occurrence may be regarded as the first-round exploration target of the Jiulongzhang volcanic basin.