大兴安岭大杨树火山盆地西缘金矿的发现及找矿意义

Discovery and prospecting significance of the gold deposit in the western margin of Dayangshu volcanic basin in Greater Khingan Mountains

大兴安岭中生代火山盆地是区域上寻找浅成低温火山热液型金矿床的有利区,前人在大杨树火山盆地西缘开展1∶5万矿产调查时,已圈定出张点和扎罗梅2处远景区。利用零星的槽探工程开展物化探异常验证:在张点矿区发现1条稳定延伸的含金石英脉,长约0.95 km,视厚度为5~15 m,最高金品位为88.25×10^(-6);在扎罗梅矿区发现2条金矿体、1条金矿化体、1条银矿体,其中I号和II号金矿体被推断为同一条金矿体,长度大于600 m,视厚度为2~3 m,最高金品位为5.83×10^(-6),IV号银矿体视厚度为4.0 m,最高品位为(50.90~310.00)×10^(-6)。综合分析两个矿区的土壤化探异常和激电中梯测量视极化率异常特征,并与区域上三道湾子等金矿床的成矿地质条件进行对比,认为张点和扎罗梅矿区的金矿点具有中—大型成矿资源潜力。大杨树火山盆地边缘金矿点的发现可为大兴安岭火山岩带的金矿勘查部署提供参考,促进勘查及研究程度的提高,有助于实现找矿突破。

The Mesozoic volcanic basin of Greater Khingan Mountains is a favorable area for epithermal volcanic hydrothermal gold deposits.Based on previous delineation of 2 gold prospect areas,Zhangdian and Zhaluomei,during 1∶50000 mineral survey carried out in the western margin of Dayangshu volcanic basin,the authors of this paper conducted verification and inspection of geophysical and chemical exploration anomalies through exploratory trench.A stable extended gold-bearing quartz vein was found in Zhangdian mining area,with a length of about 0.95 km,an apparent thickness of 5~15 m,and its highest gold grade of 88.25×10^(-6).Two gold ore bodies,one gold mineralized body and one silver ore body,were discovered in Zhaluomei mining area.No.I and No.II gold ore bodies were inferred to be the same gold ore body,with a length more than 600 m,an apparent thickness of 2~3 m,and their highest gold grade of 5.83×10^(-6).No.IV silver ore body has an apparent thickness of 4.0 m,and its highest grade is(50.90~310.00)×10^(-6).The authors analyzed the characteristics of soil geochemical anomaly and apparent polarization anomaly of the induced polarization ladder measurement in these two mining areas,and compared these conditions with the metallogenic geological conditions of Sandaowanzi and other gold deposits.The gold deposits in Zhangdian and Zhaluomei mining areas were identified to have medium to large metallogenic resource potential.The discovery of gold deposit in the margin of Dayangshu volcanic basin could provide some reference for the exploration and deployment of gold deposits in the volcanic belt of Greater Khingan Mountains,and promote the improvement of the exploration and research,which could further contribute to the prospecting breakthrough.