摘要
河南灵宝大湖金-钼矿床位于小秦岭金矿田,属典型的断控脉状矿床。成矿过程经历3个阶段:早阶段为黄铁矿—石英脉,遭受变形、破碎,应形成于挤压或压剪过程;中阶段为细粒的辉钼矿—黄铁矿—石英网脉,贯入到早阶段黄铁矿或石英矿物的裂隙(可呈共轭状),应形成于剪切环境;晚阶段石英—碳酸盐细脉具梳状构造,充填于张性或张扭性裂隙。即,流体成矿作用发生在赋矿断裂由挤压或压扭转向伸展或张扭性的过程中。早阶段只发育 CO_2-H_2O 型流体包裹体;中阶段流体包裹体类型复杂,有纯 CO_2型、CO_2-H_2O 型、H_2O-NaCl 型和含子晶包裹体,指示流体沸腾作用强烈;而晚阶段只发育水溶液包裹体。早、中、晚3个阶段的流体包裹体均一温度分别集中在400～500℃、290～470℃、220～260℃;估计的早、中阶段流体的最低捕获压力分别为138～331MPa和78～237MPa,对应于成矿深度分别为13.8km～11.0km和7.8km～8.0km。因此,成矿流体具中-高温、中-深成、低盐度、富 CO_2的特征,与中-深成造山型矿床一致。大湖金-钼矿床的成矿流体形成和演化及其成矿作用可利用 CMF 模式进行合理解释。
The Dahu Au-Mo deposit, Lingbao County, Henan Province, is a typical fault-controlled lode deposit occurred in the north part of Xiaoqinling gold field. The ore-forming process can be divided into three stages. The early stage is characterized by pyrite- quartz veins, in which minerals were structurally deformed and broken, indicating that they formed in a compression or compressive distortion setting. The middle stage is characterized by molybdenite-pyrite-qnartz stockworks （mostly coaxial or conjugated） infilling the cracks of the early-stage minerals such as pyrite and quartz, suggesting that it occurred in a tensional shear setting. The late stage is characterized by extensional open-space filling quartz-carbonate veinlets with comb-like texture. In a word, the hydrothermal mineralization occurred when the ore-hosting faults evolved from compressive to extensional. The early-stage minerals only contain CO2- H2O inclusions, whereas the late-stage minerals only contain H2O-NaC1 inclusions. Both the H2O-NaCl and CO2-H2O inclusions, together with pure CO2and daughter mineral-bearing inclusions can be observed in the middle-stage minerals, implying that strong fluid- boiling occurred in this stage. Homogenization temperatures of fluid inclusions range from 400 to 500℃ for the early stage, from 290 to 470℃ for the middle stage, and from 220 to 260℃ for the late stage. The trapping pressure are estimated at least to be 138 - 331MPa for the early stage and 78 - 237 MPa for the middle stage, respectively, corresponding to the ore-forming depth of 13.8km - 11.0km and 7.8km - 8. 0km, respectively. Therefore, the ore-forming fluid-system of the Dahu Au-Mo deposit is characterized by mesothermal-to-hypothermal, mesozonal-to-hypozonal, low salinity and CO2-rich, which is identical to those of mesozonal to hypozonal orogenic-type deposits. The origin and evolution of the ore-forming fluid and mineralizations of the Dahu Au-Mo deposit can be interpreted by the CMF model reasonably.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2008年第9期2058-2068,共11页
Acta Petrologica Sinica
基金
国家重点基础研究发展汁划“973”项目(2006CB403500)
自然科学基金项目(40730421,40425006)
中国科学院百人计划项目资助
