胶东大尹格庄金矿床构造蚀变分带特征与成矿关系

The structural-alteration zoning and mineralization of Dayingezhuang gold deposit,Jiaodong peninsula

大尹格庄金矿床是胶西北地区的特大型金矿床,为典型的破碎带蚀变岩型金矿床。研究大尹格庄金矿构造蚀变分带规律,对胶西北地区矿床研究及深部外围找矿有重要意义。通过对大尹格庄金矿床构造蚀变分带特征,以及各带岩石的岩相学、岩石地球化学、构造应力测算的系统研究,揭示大尹格庄金矿构造蚀变成矿的构造地球化学和构造物理化学过程。研究表明,①矿床断裂下盘由远矿围岩到矿体的构造蚀变分带模式为:弱钾化花岗质蚀变岩带→强钾化花岗质蚀变岩带→绢英岩化钾化花岗质蚀变岩带→黄铁绢英岩带(金矿主要发育带);②金矿由远矿蚀变带→黄铁绢英岩带,古构造差应力值呈现由小到大的变化趋势;③由远矿蚀变带→黄铁绢英岩带,Si、Na、Ba、Sr迁出,K、Fe、Cu、Zn、Pb迁入,Au含量不断增加,在未蚀变到弱钾化阶段,元素总体含量变化幅度较小,而在强钾和绢英岩化阶段变化幅度较大。成矿过程中构造应力场与岩石组分迁移具有耦合关系,绢英岩化阶段古构造差应力值较大,岩石破碎产生张性空间,同时元素含量变化幅度大,热液活动强烈,易富集成矿。

As a large gold deposit in the northwest of Jiaodong peninsula,Dayingezhuang gold deposit is an altered rock-control gold deposit in fracture zone.The zoning of structural alteration of this deposit is important to the deep peripheral prospecting of deposits in the northwest of Jiaodong.This study presents the zoning of structural-alteration,the petrogenesis,geochemistry,and calculation of tectonic stress,to reveal the structural geochemistry and structural physicochemical process of structural alteration of the Dayingezhuang gold deposit.From the distal ore surrounding rock to the ore body:①the zonation pattern of structural alteration is weakly potassic alteration granitic rock→strongly potassic alteration granitic rock→phyllic and potassic alteration granitic rock→beresite;②The paleotectonic differential stress have an increase trend;③Si,Na,Ba and Srwaslost,K,Fe,Cu,Zn and Pb was externally supplied,and Au increased steadily in the whole mineralized process.The content of elements has a slight varies from unaltered rock to weakly potassic alteration granitic rock,with large amplitudes of variations from strongly potassic alteration granitic rock to beresite.During the mineralization process,the tectonic stress field and the migration of chemical compositions from rocks often display coupling behavior,as fracture and extensive space are often well developed within the rocks during the sericitization due to the relatively large paleotectonic differential stress,and this process is combined with the large variation in its compositions associated with intensive hydrothermal activity;all these factors together facilitate mineralization.