摘要
在金属内生矿矿田地质研究中,构造变形岩相既能反映矿田形成的构造应力场特征,又能揭示其地球化学特征和物理化学条件.胶东金矿集中区在全球金矿中独具特色,其金矿储量规模位居世界第三,大尹格庄金矿田是区内特大型金矿田之一.在矿田构造蚀变岩相研究基础上,厘清矿田成矿构造物理化学参量之间的关系,探讨构造作用通过影响矿田成矿物理化学条件驱动金成矿作用问题显得尤为必要.本文选取代表成矿流体成分、温压、性质和成矿构造等条件的构造物理化学参量,采用因子分析法,探讨矿田构造成岩成矿问题.结果显示:流体包裹体成分CO2/H2O、酸碱度(pH)、氧逸度(lgfO2)、构造附加静水压力(Ps)、流体包裹体均一温度以及流体包裹体最小压力(Pmin)等参量代表的构造物理化学条件对成矿的影响较大,CO2/H2O、lgfO2、Ps、均一温度、Pmin所代表的成矿流体成分、性质、温压条件及构造作用的影响是正相关的,而pH影响是负相关的;矿田黄铁绢英岩带、黄铁绢英岩化花岗质碎裂岩带和强钾长石化花岗岩带中,构造附加静水压力(Ps)、流体包裹体成分CO2/H2O、氧逸度(lgfO2)、流体包裹体最小压力(Pmin)和均一温度均依次呈现先升高再降低的趋势.流体包裹体成分Na+/K+、F-/Cl-参量代表的成矿物理化学条件对于成矿的影响是负相关的,在黄铁绢英岩带、黄铁绢英岩化花岗质碎裂岩带和强钾长石化花岗岩带中,F-/Cl-依次呈现逐渐降低的趋势,Na+/K+则依次呈现逐渐增大的趋势.构造附加静水压力(Ps)能够促使成矿流体从Ps较高的部位向较低的部位运移并沉淀成矿.构造物理化学参量的高低值之间存在构造物理化学界面,金矿体主要位于界面的构造应力松弛部位.
Abstract
In the study of orefields with endogenetic metallogenesis,tectono-deformation lithofacies can not only reflect the characteristics of tectonic stress field during the formation of the deposit but also reveal their geoche-mical features and physicochemical conditions.The Jiaodong gold-concentration area has a unique characteristic among global gold deposits,with its scale of gold reserves ranking third in the world.It is noteworthy that the Dayin'gezhuang orefield is one of the super-large gold fields in this region.Based on previous research on tec-tonic alteration lithofacies,it is particularly necessary to clarify the relationship among the tectono-physicoche-mistry parameters and to delve into how tectonic processes can drive gold mineralization by influencing the phys-icochemical conditions of ore formation.This study selected tectono-physicochemical parameters representing the composition,temperature and pressure,properties of ore-forming fluids,and conditions of ore-forming structures in order to analyze tectonic diagenesis and mineralization.The results show that the tectono-physico-chemistry conditions represented by fluid inclusion components such as CO2/H2O,pH,oxygen fugacity(lgfO2),tectonic additional hydrostatic pressure(Ps),homogenization temperature of fluid inclusion,mini-mum pressure of fluid inclusion(Pmin),and other parameters have a significant influence on ore formation.The effect of the ore-forming fluid's composition,properties,temperature and pressure conditions,and the tec-tonic process represented by CO2/H2O,lgfO2,Ps,homogenization temperature,and Pmin are positively corre-lated,while the effect of pH shows a negative correlation;additionally,in the pyrite-sericite zone,the pyritic-sericitic granitic cataclastic zone,and the strong potassic feldspar granite belt of the ore field,the tectonic ad-ditional hydrostatic pressure(Ps),fluid inclusion component CO2/H2O,oxygen fugacity(lgfO2),minimum pressure of fluid inclusion(Pmin),and homogenization temperature of fluid inclusions exhibit a trend of initially increasing and then decreasing.The ore-forming physical and chemical conditions represented by fluid inclusion component Na+/K+and F-/Cl-have a negative correlation with ore formation.In the pyrite-sericite zone,pyritic-sericitic granitic cataclastic zone,and strong potassic feldspar granite belt,F-/Cl-demonstrate a grad-ually downward trend,while Na+/K+exhibits the opposite trend.Tectonic additional hydrostatic pressure(Ps)can drive ore-forming fluids to migrate from areas with higher Ps to lower Ps,leading to ore precipitation.There is a tectono-physicochemistry interface between the high and low values of tectono-physicochemical param-eters,with gold deposits primarily located in stress relaxation zones at this interface.
基金项目
国家科技支撑计划项目(2014BAB05B00)
甘肃省高等学校创新基金项目(2022B—130)
兰州财经大学科研项目(Lzufe2021C—014)
国家科技期刊平台
NSTL
万方数据