陕西三官庙金矿床地质特征、原生晕分带特征及其找矿意义

Geological Characteristics,Geochemical Characteristics of Primary Halos and Their Prospecting Significance about San'guanmiao Gold Deposit in Shaanxi Province

三官庙金矿床处于秦岭造山带南秦岭北部逆冲推覆构造带内,金矿床产于镇安—板岩镇主断裂及其南分支断裂夹持的构造透镜体中,构造控矿明显,赋矿地层为青白口系耀岭河组。在矿产地质调查研究的基础上,从金矿体特征、赋矿地层及岩性、构造与成矿、岩浆活动与成矿、矿石特征和金的赋存状态6个方面对金矿地质特征进行了系统总结。载金矿物主要为毒砂,金矿物分布于非金属矿物与毒砂粒间,以单粒金居多,形态主要为片状、粒状、麦粒状和树枝状。矿床原生晕地球化学特征研究表明,As、Sb、Hg等头晕指示元素大多位于金矿体中上部,具较高异常浓集中心,说明矿体整体剥蚀程度较浅;Bi、Mo、Co、Ni等尾晕指示元素异常较弱,说明已有工程未控制到矿体尾晕;Au1号矿体部分地段和Au3号矿体在16线附近由浅至深头晕元素异常强度具增高趋势,说明矿体向深部仍有一定延伸。综合研究认为三官庙金矿床属于中温岩浆热液型金矿床,矿床深部及外围具较大找矿潜力,深部Ⅰ、Ⅱ号找矿靶区及外围北矿化蚀变带东延地段及南矿化蚀变带为下一步找矿方向。

San＇guanmiao gold deposit,obviously controlled by fault structure, is located in the thrust-nappetectonic belt of the northern block of Southern Qinling, in the tectonic len between the Zhen＇ an-Banyanzhen faultand its south branch fault.The host strata of the deposit is the Yaolinghe Formation of the Qingbaikou System.With the exploration and research carried out on the gold deposit by the author since 2014, the scale of the depositwas expended,the prospecting direction was pointed out.In this paper, the geological characteristics of San＇guanmiao gold deposit are systematically stated from six aspect：the ore body characteristics, the host strata andlithology, the relationships between tectonic activity and mineralization, the relationship between magrnatism andmineralization, the ore characteristics, the occurrence of gold.The main gold-bearing minerals is arsenopyrite.Thenative gold mainly distributes between non-metallic minerals and arsenopyrite particles, between two non-metallicmineral particles, between two arsenopyrite particles.The mainly occurrence of the native gold is single gold.Thenative gold particles is flaky, granular, grain liked and dendritic.According to the research of the geochemicalcharacteristics of primary halos ,the characteristics and the law are summarized systematically.The front haloelements（As-Sb-Hg） with strong anomaly appear in the top part of ore body, indicating that the denudation of theore bodies is shallow.The tail halo elements （Bi-Mo-Co-Ni） are weak, indicating that tail halo is not found in theexisting prospecting work.In some area of Aul and Au3 around 16th exploration line, the front halo is gettingstronger in deeper part,indicating that the ore body has a certain extension to the depth.By comprehensiveresearch and discussion, San＇guanmiao gold deposit is classified as medium temperature magmatic hydrothermaltype, the prospecting potential in deep and periphery is large.The I and II prospecting target, the east of northmineralized alteration zone and the south mineralized alteration zone are considered as the future prospectingdirection.