湘西牛尾坡金矿床地质特征、控矿因素及找矿前景分析

Analysis of geological characteristics,ore-controlling factors and prospecting potentialsin Niuweipo Gold Deposit in Western Hunan

湘西牛尾坡金矿床产于板溪群马底驿组,赋矿岩性为灰白色硅化砂岩。其顶板、底板均为灰绿色粉砂质板岩夹灰绿色变质砂岩及紫红色粉砂质板岩。金矿体均产于马底驿组的灰白色硅化砂岩中;单个矿体长60-200余m,厚度0.49-5.65 m,平均厚度1.7 m;金平均品位4.1×10-6以上,主矿体最大控制斜深已达到680余m;矿体呈柱状、透镜状、薄饼状、脉状产出,矿脉（体）产状与地层产状一致。研究表明,牛尾坡金矿床成因类型是属于层间破碎蚀变石英脉型金矿床,矿床严格受地层、岩性及构造因素控制;矿床已达到中型规模,在该矿区深部、东部及外围（矿区南部F18、F26附近）具有大型以上规模金矿床的找矿前景。

Niuweipo Gold Deposit in Yuanling County occurs in the gray silicified sandstone of Madiyi Formation, Banxi Group. The roof and the bottom are sage-green silty slate plus sage-green meta-sandstone and mauve silty slate. All gold orebodies occur in the gray silicified sandstone of Madiyi Formation. The length of a single orebody is 60 - 200 meters, and the thickness is 0.49 -5.65 meters （average 1.70 meters）. The average gold grade is 4.1 ×^10-6 or above. The maximum controlling depth in dip for the major orebody is 680 meters. The shapes of the orebodies are columnar, lenticular, pancake-like and vein. The occurrence of the veins （orebodies） is consistent with the strata. The study indicates that the genetic type of Niuweipo Gold Deposit is quartz vein with interlayered broken alteration. The deposit is strictly controlled by strata, rock properties and structures. It is a medium-sized deposit. It has prospecting potentials for large scale deposits in the deep area, east area and surrounding area （ southern area near FlS, F26 ）.