【作者】 马学东；

【导师】 杨立强；

【作者基本信息】 中国地质大学（北京） ， 矿产普查与勘探， 2011， 硕士

【摘要】 新城金矿床是胶东焦家金矿田内的超大型焦家式金矿床。论文以详细的矿床地质调查为基础,对该金矿床控矿构造、蚀变分带及矿化网络结构进行了研究。焦家主断裂及其次级断裂构造是金矿床最重要的控矿因素,直接控制了矿体的形成及分布。由于区域构造应力场的长期演化,这些断裂构造经历了多期次构造活动:成矿前韧性剪切活动、成矿早期压性韧-脆性剪切活动、成矿期压剪性构造活动及张剪性构造活动、成矿后张性构活动五个时期。围岩蚀变受断裂构造控制,水平方向具明显的分带性,但并非简单的线性分带特征。在焦家断裂带下盘,自主断裂面向外,蚀变岩有一定渐变趋势:断层泥→黄铁绢英岩→绢英岩→绢英岩化花岗岩→硅化-钾化花岗岩→新鲜花岗岩(-630m以上为黑云母花岗岩、-630m以下为花岗闪长岩)。运用质量平衡计算方法对围岩热液蚀变过程中元素质量迁移进行了研究。从新鲜花岗岩到各种蚀变岩过程中:Si、Na、Al元素主要为迁出,Fe元素主要为迁入,Ca、K元素既有迁入也有迁出;微量元素Ba、Pb、Zn、Sr表现活跃,其次为Cu和Rb。其中Ba、Sr多为迁出,Pb、Zn及Cu多为迁入。新城金矿床黄铁绢英岩型矿化(Ⅰ号矿体)和含金石英脉型矿化(Ⅴ号矿体)是同源成矿溶液在同一构造作用下不同构造(断裂带)部位的产物,是由于控矿构造的部位不同、级序高低、性质差异所造成的:缓倾斜压扭性主控断裂中构造活动强烈,岩石破碎强烈,流体以渗透交代作用为主,发育蚀变岩型矿化;焦家主断裂下盘远离主断裂的次级构造以张扭性为主,成矿流体以充填为主,利于成矿矿物质沉淀而形成硫化物石英脉型矿体。焦家断裂构造分带与蚀变矿化分带有良好的吻合性和统一性,呈水平分带为主的空间分带性。从主断裂面近旁的挤压片理带至远离断面的节理带,其蚀变岩亦由黄铁绢英岩化带至远离断面的钾化带,矿化类型也出现由破碎蚀变岩型矿化带至石英脉型矿化带变化。更多还原

【Abstract】 Xincheng gold deposit is one of the largest gold deposits, which is“Jiaojia Type”gold deposit in the Jiaojia gold field of Jiaodong Peninsula. Based on the detailed field geological survey, characteristics of ore-controlling structures, alteration belt as well as the mineralization network were studied in this paper.The Jiaojia fault and its secondary structures are the most important ore-controlling factors of Xincheng gold deposit, which directly controlled the formation and distribution of the deposit. Owing to long-term evolution of regional tectonic stress field, the Jiaojia main fault and its secondary structures experienced multistage structure-activity: ductile shearing activity before the ore-forming stage, compression-ductile-brittle shearing activity before the ore-forming stage, compression-shearing and stretching-shearing activity of ore-forming stage, stretching activity after ore-forming stage.Wall rock alteration of Xincheng gold deposit, controlled by fault, has a clear belt, which is not simply linear, however. From the footwall of major fracture planes to the external, altered rocks present a gradual change trend: from fault gouge, through beresitization belt, sericite-quartz alteration belt, granite of sericite-quartz belt and alteration silicified-potassic granitic belt, to fresh granite (biotite granite exists up -630 m while granodiorite exists below -630 m). By the method of mass balance calculation, the migration of the elements in the process of wall rock alteration, which means fresh granite altered to altered rocks, was studied. The result of study shows that the moving out elements are mainly Si, Na and Al, the immigration elements are mainly Fe, and both cases present in elements of Ca and K; trace elements of Ba, Pb, Zn, Sr are active, and secondly are Cu and Rb, of which, Ba and Sr always move out and Pb, Zn and Cu mostly move in.The beresitization mineralization of Xincheng gold deposit (No.I orebody) and Au-bearing quartz vein-type mineralization are the production of the same ore- forming fluids under the same tectonic activity but different structural site, which were caused by ore-controlling structure of different parts, level of sequence and property. Tectonic activity in the main slightly inclined fault with shear- compressional mechanical property, act intensively with strong fragment of rocks, and the ore-forming fluids characterized with infiltration metasomatism, with altered rock-type mineralization while in the secondary structure with the tenso-shear property which is the footwall of Jiaojia fault, far away from the main fault, the ore-forming fluids characterized with the ore-forming process of filling which was favorable for the precipitation for ore-forming mineral and forming sulfide quartz vein type ore bodies.The structure belt of Jiaojia faults coincide with the belt of alteration mineralization and the mineralization type presents as domimated horizontal belt. The alterated rocks changed from beresitization belt into potassic belt with compressional schistosity belt near the fault plane to the fissuring belt far from fault plane, and the mineralization types are changed from fractured altered rock type into Au-bearing quartz vein-type mineralization.更多还原