西藏哈海岗达龙钼钨矿床找矿地质条件及找矿标志

达龙钼钨矿床，上二叠系旁那组浅变质砂岩与板岩互层是主要的赋矿层位；构造裂隙填充的矽卡岩是钨矿体的赋矿岩石；达龙背斜与达龙断裂的构造叠加部位是主要的控矿构造；喜山期的复式杂岩体是成矿的主要矿源体及热源体。这些因素相互作用、相互配合，为矿床的形成提供了必要的地质条件。矽卡岩型白钨矿石常与浸染状黄铜矿、磁黄铁矿共生；围岩蚀变发育、并具分带性，以钨矿体为中心，向外依次为矽卡岩化→磁黄铁矿化→硅化、浸染状黄铁矿化→绿泥石化、绿帘石化→碳酸盐化、薄膜状黄铁矿化→绢云母化、高岭土化。在C u、Mo、W的次生晕异常浓集中心均有工业矿体出现。瞬变电磁与激电中梯的低阻高极化率异常为本区的矿致异常。

The geological condition and criteria for Dalong Mo-W deposit prospecting in Hahaigang,Tibet Autonomous Region

In the Dalong molybdenum-tungsten deposit,the shallow metamorphic sandstone and slate inter-layer of upper Permian Pangna Formation is the main ore-bearing horizon.Skarn filling structural fracture is the host rock of tungsten ore.Structural superimposed parts in Dalong anticline and Dalong fracture are the main ore-controlling structures.The Himalayan period complex rock body provides main ore sources and heat source for mineralization.The cooperative factors mentioned above have supplied necessary geological conditions for tungsten mineralization.Skarn type scheelite ores are often paragenesis with impregnated chal-copyrite and pyrrhotite.The wall-rock alterations are universal,and the alteration can be divided from the center of tungsten body to the outside as：skarnization→ pyrrhotization→ silicification;impregnated pyritiza-tion→ chloritization;epidotization→ carbonation;film like pyritization→sericitization→ kaolination.Indus-trial orebody appeared in the center of secondary halo anomaly concentration of Cu,Mo,W.Low resistivity and high polarization showed in transient electromagnetics and induced electric intermediate gradient method are mineralizedanomalies.