| The Dongfeng gold deposit lies in the Linglong gold orefield,wherein it is controlled by the main structures in the downthrow of the Zhaoping?Zhaoyuan–Pingdu?fault.Exposed strata in the orefield include the Neoarchean Jiaodong rock group and Cenozoic Quaternary loose accumulations.Brittle structures hosted in the study area are typically NNE-trending faults;magmatic rocks are primarily Mesozoic Linglong and Wendeng sequences.The Linglong sequence adamellite is mainly found in the downthrow of the Potouqing fault;the Tangezhuang sequence trondhjemite and Wendeng sequence adamellite are mainly found in the upthrow of the Potouqing fault.Three lode groups,composed of 26 orebodies,have been delineated in the study area.206?-1,the largest orebody in the area distributed as stratiform beds or large veins,characterizes branching–recombination,expansion–shrinkage,pinch-out–reoccurrence cycles.This orebody occurs in the same attitude as the main fault plane and strikes around25°with an average Au grade of 3.65×10-6.Metallic minerals inside the ores include pyrite and chalcopyrite.The ore textures mainly include crystalline-granular texture and secondarily cataclastic and interstitial textures.The ore structures mainly include disseminated,veined,crumby,and spotted structures,although brecciated and cross-veined structures are also present.Chronologically,the metallogenetic history of the Dongfeng gold deposit can be separated into three stages:a gold–quartz–pyrite stage?I?,a gold–quartz–polymetallic sulfide stage?II?,and a quartz–carbonate stage?III?,with the first two stages representing the main ore-forming period.Stage I featured a high Au content,as well as a high As,Cu,Pb,and Zn content.Stage II featured an even higher Au content and,relatively,the highest Ag,Cu,Pb,Zn content;Stage III,which involved almost no ore-forming activity,featured a low Au content?Au?0.5×10-6?related to mere mineralization and a very low Ag,Sb,Cu,Pb,and Zn content.The overall metallogenic evolution is a superimposition of multiple ore-forming and halo-forming stages and phases.The orebodies–halos from different metallogenic stages have accounted for the complicated superimposed structures that are isospatial,almost isospatial,partly isospatial,or superimposed only between the tail halo of the upper ores and head halo of the deep blind ores.The deep part of the Dongfeng gold deposit consists of fractured altered rocks?the Jiaojia style?.Physically,the gold orebodies there are anomalous with low resistivity?with medium subhigh resistivity?,high chargeability,high time constant,and low frequency correlation frequency.In this paper,we summarized an integrated deep ore prospecting model using geological theories and geological ore prospecting methods as well as geophysical techniques,in the light of the characteristics of the structural superimposed halos in the Dongfeng gold deposit of the Linglong gold orefield.According to the ore-controlling structures and ore-forming pattern of this deposit,we finally established the favorable ore-forming spaces in the area and predicted that this deposit contains an Au metal quantity of approximately 3.4 t. |
PDF Full Text Request