烃气测量在南岭魏家隐伏钨矿区找矿预测中的应用

Application of Hydrocarbons in Concealed Tungsten Ore Prediction in Weijia,Nanling Area

魏家钨矿位于湖南道县祥霖铺镇,产出于铜山岭岩体北部附近的祥霖铺斑岩群,是新一轮矿产远景调查时利用综合信息找矿发现的大型矽卡岩型钨矿.由于矿体埋藏深度近500m,矿体上盘为灰岩盖层,表层被几十厘米至几百厘米的土壤覆盖,常规指示元素难以指示深部矿体.研究表明,在成矿过程中烃类组分参与了成矿元素的迁移、富集,因此选取该区进行烃气测量实验,验证其对覆盖区深部隐伏钨矿的指示效果.研究了见矿钻孔ZK801的46个岩心样的酸解烃和矿体上方3条剖面的土壤热释烃含量特征,结果表明在斑岩体、矿体、围岩中除甲烷外烃类组分含量依次降低,甲烷、烯烃和重烷比例明显不同;标准化后矿体配分曲线与斑岩体和围岩均具有相似性;土壤剖面中热释烃在矿体上方呈现双峰分布,与传统指示元素相比对深部矿体有更好的指示效果;研究区烃组分地球化学图显示矿体上方烃类组分呈现低值带,矿体周围为明显的异常区.因此烃气测量在覆盖区对深部矿体有较好的指示意义.

Weijia tungsten ore is located at Xiang Linpu Town,Hunan Province.It is in the Xiang Linpu porphyry groups near the Tong Shanling porphyry.The large skarn type deposit was detected using comprehensive exploration method during the recent exploration activities in China.Being buried deeply in 500mand covered by limestone and thick soil in the surface,it has hardly been indicated by traditional pathfinder elements.It is proved that hydrocarbons promoted the transport and enrichment of elements in the ore forming,so Weijia tungsten ore is taken as a case to study the effect of hydrocarbons to the concealed deposits in coverage area.Acidolysis hydrocarbon of 46rock samples in ZK801and heat release hydrocarbon of 3soil profiles were analyzed.The results show that the contents of hydrocarbons decrease from porphyry,ore body to wall rock,and the rates of methane,olefins and heavy alkane are different in porphyry,ore body and wall rock.The standard curves shapes of ore are similar to those of the porphyry and wall rock.The soil heat release hydrocarbons show bimodal distribution and low value above the ore body.This study proves that the hydrocarbons are more useful to indicate the concealed mine than the traditional pathfinder elements.