老挝巴乌县怀亮金矿地质地球化学特征及找矿预测

Geological and Geochemical Characteristics and Ore-prospecting Prediction of the B.Houayluang Gold Deposit in Bak-Ou County,Laos

老挝巴乌县怀亮金矿区地处云南三江成矿带的南延地段,属于热液型铅锌矿、火山沉积型铜矿、斑岩型-岩浆热液型铜金矿和沉积型钾盐矿床的重要成矿带。为查明矿区铜金多金属矿的资源潜力,结合地质、遥感、物化探及探矿施工等工作成果,探讨了怀亮金矿形成的地质背景、矿区地质特征、矿床地质及地球化学特征、成矿模式等,并圈定了3处找矿靶区,即西部找矿靶区(Ⅰ)、东部找矿靶区(Ⅱ)和南部找矿靶区(Ⅲ)。西部找矿靶区(Ⅰ)面积约13.63 km^(2),发育两条断裂构造,圈定了HT1、HT2、HT4、HT5、HT6号化探综合异常,发现了怀磊沟金矿点,探槽、剥土揭露了7条金矿化体,矿化主要赋存于蚀变绢云千枚岩、闪长岩、灰岩等浅变质岩与岩体接触边部,预测靶区金矿找矿潜力较大。东部找矿靶区(Ⅱ)面积约5.18 km^(2),圈定了HT3号化探综合异常,在石英破碎带中发现了2条铜矿化脉,围岩为安山岩,预测靶区具有一定的金(铜)矿找矿潜力。南部找矿靶区(Ⅲ)面积约1.88 km^(2),见一条NE—SE向断裂从区内西侧经过,发现了怀卡金矿点,探槽、剥土揭露了2条金矿化体(带),矿化主要赋存于蚀变安山岩中,预测靶区具有较好的金矿找矿前景。推断矿区矿体的形成可能与地层岩性、岩体或断裂构造有关,矿床类型为构造蚀变—中低温热液型矿床。在上述分析的基础上,从地球化学、构造、围岩蚀变、矿物组合等角度总结了找矿标志,以期为三江成矿带金矿找矿起到一定的启示作用。

B.Houayluang Gold Deposit in Bak-Ou County,Laos is located in the extension part of the southern Sanjiang metallogenic belt in Yunnan Province,which is an important metallogenic area of hydrothermal type Pb-Zn deposit,volcanic sedimentary type Cu deposit,porphyritic-magmatic hydrothermal type Cu-Au deposit and sedimentary type deposit. In order to find out the potential of copper-gold polymetallic mineral resources in the mining area,based on the working results of geological,remote sensing,geophysical and geochemical exploration,exploration engineering investigation and so on in the area,the geological and metallogenic background,geological and geochemical characteristics,metallogenic model are analyzed,and three prospecting target areas are divided in the study area,i.e. western prospecting target area(Ⅰ),eastern prospecting target area(Ⅱ)and southern prospecting target area(Ⅲ).The area of western prospecting target area(Ⅰ)is about13.63 square kilometres,two faulted structures are developed in the area,five geochemical comprehensive anomalies(HT1,HT2,HT4,HT5,HT6)are delineated,one gold mineralization point is discovered in B.Houayle,seven gold mineralized bodies are disclosed through the trench and stripping engineering,mineralization occurs mainly at the contact edge of altered sericite,diorite,limestone and other epimetamorphic rocks,and it is predicted that the target area(Ⅰ)has good prospecting potential for Au deposit.The area of eastern prospecting target area(Ⅱ)is about 5.18 square kilometres,one geochemical comprehensive anomalies(HT3)is delineated,two copper mineralized veins are discovered in the quartz fracture belt,andesite is the surrounding rock,and it is predicted that it has prospecting potential for Au or Cu deposit in target area(Ⅱ).The area of southern prospecting target area(Ⅲ)is about 1.88 square kilometres,A NE-SE fault passes through the west side of the area,the B.Houaykha gold mine point is discovered,two gold mineralized bodies(belts)are disclosed through the trench and stripping engineering,mineralization occurs mainly in altered andesite,and it is predicted that the target area(Ⅲ)has prospecting potential for Au deposit. It is concluded that the formation of mineralized bodies may be related to the lithology,rock mass or fault structure,this deposit belongs to structural meso-epithermal hydrothermal type gold deposit.Based on the above discussion results,some prospecting indicators from the aspects of geochemistry,structures,alteration of surrounding rock and mineral assemblage are proposed,which have an reference significance for Au-prospecting in Sanjiang metallogenic belt in China.