多维度化探异常研究在黔西南者相金矿床深部成矿预测中的应用

Application of the multi-dimensional study of geochemical anomalies in deep metallogenic prediction of the Zhexiang gold deposit in southwestern Guizhou, China

由于缺少有效的深部勘查技术手段,如何在黔西南灰家堡背斜已探明典型矿床的深部及外围获取成矿作用信息,从而扩大找矿规模,成为地勘单位工作的重点和难点。本文以黔西南地区灰家堡背斜东侧的者相金矿床为例,为了真实反映深部地质异常特征,以深部含矿地层——龙潭组为研究对象,从勘查线剖面、纵剖面及深部三维平面3个维度出发,对深部Au异常进行全方位的钻孔化探异常信息提取,总结化探异常分布规律,对者相金矿深部成矿潜力进行评价。综合利用迭代法结合直方图法和钻孔样长加权平均品位法对深部钻孔化探数据进行处理,获得矿区龙潭组地层Au异常背景值范围为(0.04~0.12)×10^(-6),异常下限约为0.24×10^(-6)。两种方法处理后的等值线异常图显示:Au异常分布特征与深部矿体特征具有较高的吻合性,所有剖面的Au高异常分布范围和已查明含矿带(体)的形态高度吻合,大范围且未闭合的Au高异常与龙潭组一段中的F20断层倾向分布一致,Au异常三维分布特征显示为矿区中部近EW向分布的高异常带与灰家堡背斜轴部走向一致。综合多维度的化探异常及研究区地质特征,查明F20断层为矿区的主要导矿和控矿断裂,矿区外围的北边、东边深部具有较大的成矿和找矿潜力,据此圈定了两个找矿靶区,建议进行工程验证。本次研究为指导灰家堡其他矿区的矿产勘查起到了示范作用,研究方法的可行性对其他矿区的化探异常研究具有借鉴作用。

Due to the lack of effective deep exploration techniques,it has become a key and difficult task to expand the scale of pros-pecting by obtaining the mineralization information in the deep and peripheral areas of the proven typical deposits of the Huijiabao anti-cline in southwestern Guizhou.To truly reflect the characteristics of deep geological anomalies,this study investigated the deep ore-bearing Longtan Formation of the Zhexiang gold deposit in the eastern Huijiabao anticline.The information on deep Au anomalies was extracted through geochemical exploration in boreholes of any azimuth according to the profiles,longitudinal profiles,and deep 3D planes of survey lines.Then this study summarized the distribution patterns of geochemical anomalies and evaluated the deep metallo-genic potential of the Zhexiang gold deposit.The geochemical data obtained from deep boreholes were processed using the iterative his-togram method and the sample length weighted average grade method,respectively.The results show that the Longtan Formation in the mining area had Au anomaly background values of(0.04~0.12)×10^(-6) and an anomaly threshold of about 0.24×10^(-6).As revealed by the anomaly contour maps generated from the processed data using the above two methods,the distribution characteristics of Au anoma-lies are in high agreement with those of deep ore bodies,and the distribution ranges of high Au anomalies in all profiles are highly con-sistent with the morphologies of the proved ore-bearing zones(bodies).Moreover,the large-scale and unclosed high Au anomalies fol-low the dip direction of fault F20 in the first member of the Longtan Formation.The 3D distribution of Au anomalies shows that the near-ly EW-directed high anomaly zone in the central mining area is consistent with the axial region of the Huijiapu anticline.As indicated by the analysis of the multi-dimensional geochemical anomalies and the geological characteristics of the study area,fault F20 is the main ore transmitting and controlling fault in the mining area,and the northern and eastern deep parts around the mining area have great met-allogenic and prospecting potential.In addition,two prospecting targets were delineated,needing further engineering verification.This study plays an important demonstration role in guiding the exploration of other mining areas in the Huijiabao anticline.The feasible study methods can be referenced for the study of geochemical anomalies in other mining areas.