黔西北小河边铁多金属矿床构造特征与找矿预测

Structural characteristics and prospecting prediction of the Xiaohebian iron-polymetallic deposit, NW Guizhou, China

小河边铁多金属矿床地处黔西北垭都—蟒洞成矿带内,本文重点研究了该矿床的构造特征及其构造控矿规律,并采用构造地球化学方法进行找矿预测。研究表明,小河边多金属矿床出露大面积石炭系黄龙组和泥盆系望城坡组中-粗晶白云岩,矿区内断裂发育,白云石化、方解石化蚀变面积广且强度大,反映该矿床具备十分有利的"地层岩性-构造-蚀变"成矿地质条件;矿区NW向断裂多为垭都—蟒洞断裂的次级断裂,近SN向断裂与NE向断裂共同控制着矿化、蚀变空间展布,近SN向与NE向断裂的交汇地段是成矿的有利部位。断裂构造岩元素可分为铅锌等中温成矿元素组合、白云石化蚀变元素组合、低温成矿元素组合和地层主微量元素组合,推断其成矿流体运移方向为SN向断裂内由N向S运移、NE向断裂内自NE向SW运移,依据成矿规律及地球化学异常,圈定了4个找矿靶区。

The Xiaohebian iron polymetallic deposit is located in the Yadu-Mangdong metallogenic belt in the Northwestern Guizhou. In this paper, we have focused on studying its structural characteristics and its structural ore-controlling rules, and carried out the ore-prospecting prediction by means of structural geochemistry. The results show that the medium-coarse grained crystalline dolomites of the Carboniferous Huanglong Formation and the Devonian Wangchengpo Formation are outcropped in a large area of the Xiaohebian deposit. The faults are well developed, and the alterations including dolomitization and calcitization are strongly and widely developed in the deposit, indicating that there are favorable combined ore-forming geological conditions of the "formation lithology-structure-alteration". The NW-trending faults in the deposit are mainly secondary faults of the Yadu-Mangdong Fault. The SN-trending faults and NE-trending faults are jointly controlled the spatial distribution of mineralization and alteration, with their intersection parts favorable for the mineralization. The elemental associations of fault tectonites can be classified into the Pb-Zn mesothermal metallogenic element association, dolomitization element association, low-temperature metallogenic element association, and major and trace element association of strata, respectively. It is inferred that the ore-forming fluid was migrated from N to S in the SN-trending faults and from NE to SW in the NE-trending faults, respectively. Based on the metallogenic regularity and geochemical anomalies of the deposit, four prospecting targets have been delineated in the area.