半干旱荒漠草原覆盖区地气测量方法研究——以内蒙古维拉斯托锌铜多金属矿床为例

Geogas Measurement Experiments in the Semi-arid Desert Steppe:An Example of the Weilasituo Zn-Cu Polymetallic Deposit in Inner Mongolia

半干旱荒漠草原是我国重要的地貌景观类型,由于长期受风成沙的干扰,常规化探方法在该区找矿效果不理想。本文以位于内蒙古半干旱荒漠草原覆盖区的维拉斯托锌铜多金属矿为研究对象,进行了地气测量实验。同时,为筛选地气组分中的有效指示元素,对矿石矿物进行了采样分析。结果表明该矿区矿石矿物主要为闪锌矿、黄铜矿、磁黄铁矿、毒砂,成矿元素主要为Cu、Zn、Ag、As、Fe,部分矿石中Pb、Bi、Cd、Mn、Ni含量较高。地气组分中异常元素种类与矿石成矿及伴生元素一致,且异常位置与隐伏矿体基本吻合。地气与矿石、围岩的稀土元素(REE)球粒陨石标准化配分图解显示,异常区地气REE配分特征与矿石接近,说明地气成分继承了隐伏矿体的地球化学信息。以上研究证明地气测量可作为半干旱荒漠草原覆盖区寻找隐伏锌铜多金属矿的有效手段。

Semiarid grassland is an important landscape type in China. Due to the impact of wind and sand,conventional geochemical exploration methods cannot work well for mineral exploration in these areas. The geogas survey method is one possible approach to solve this problem. This paper presents an experiment on this technique in the Weilasituo zinc-copper polymetallic deposit in the semi-arid grassland of Inner Mongolia. To choose indicator elements of geogas components in this area,we have analyzed ore samples. The results show that(1)sphalerite,chalcopyrite,pyrrhotite,arsenopyrite are the main minerals. Cu,Zn,Ag,As and Fe are dominant mineralization elements,and the content of Pb,Bi,Cd,Mn and Ni in some minerals is high.( 2)The types of geochemical anomalies in the geogas are consistent with the elements of the ores in this area,and largely match the positions of the concealed orebodies.(3)The chondrite-normalized REE patterns of geogas,ore and surrounding rocks suggest that the REE characteristics of geogas are close to those of the ores,implying the composition of the geogas contains geochemical information of hidden orebodies. This experiment proves that the geogas survey method is an effective tool to search for concealed zinc-copper polymetallic deposits in semiarid grassland areas.