甘肃小柳沟铜钨矿床找矿地质条件及找矿标志

The geological condition and criteria for Cu-W deposit prospecting in Xiaoliugou, Gansu Province

小柳沟铜钨矿床 ,朱龙关群下岩组上岩段及上岩组中下岩段是主要的赋矿层位及矿源之一 ;矽卡岩化灰岩及角闪云母片岩是钨矿体的赋矿岩石 ;“D”型穹隆构造、环状和放射状断裂以及岩体与围岩接触带是主要的控矿构造 ;隐伏二长花岗岩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。含钨石英脉及矽卡岩型白钨矿石常与细粒浸染状黄铜矿、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、大理岩化→硅化、黄铁矿化→绿泥石化、绿帘石化→碳酸盐化→绢云母化。当白钨矿的重砂异常 >0 0 5 % ;次生晕w(W) >5 0 0× 1 0 - 6;原生晕w(W) >5 0 0× 1 0 - 6,w(Cu) >1 0 0 0× 1 0 - 6时均有钨、铜矿体出现。

In the Xiaoliugou copper-tungsten deposit,the upper part of the subsection of Zhulongguan group and the lower middle part of the upper section of Zhulongguan group are the main source of ore and ore-bearing bed.Skarnization limestone and amphibole-mica schist are the main host rock.The primary ore-control structure consists of 'D' pattern quaquaversal structure,ring and radiating faults and the contact zone between rock mass and surrounding rocks.The hidden granite mass provides main ore and heat resource for mineralization.The cooperation factors mentioned above have supplied necessary geological conditions for tungsten mineralization.The quartz vein and scheelite ususlly parageneses with impregnation chalcopyrite and pyrite.The wall-rock alterations are universal,and the alteration can be divided from the center of tungsten body to the outside just like the following:skarnization and marbleization→silication and pyritization→chloritization→carbonation→sericitization.Tungsten and copper bodies will be found when panned sample abnormality is greater than 0.05%,tungsten content in secondary halo greater than 500×10 -6 ,tungsten content in primary halo greater than 500×10 -6 ,copper content in primary halo greater than 1 000×10 -6 .