海南二甲金矿的动力变形成矿作用及构造地球化学模拟实验研究

海南二甲金矿是一个与戈枕韧性剪切带活动明显相关的金矿床。利用构造地球化学方法和构造地球化学模拟试验 ,研究了戈枕韧性剪切活动与金成矿的关系 ,结果显示 :动力变形作用不仅导致混合岩发生明显的糜棱岩化 ,而且使矿物成分、化学成分发生明显变化 ,同时伴随着一定的构造岩流体活动。动力变形中岩石的变形机制可发现有多种 ,其中以恢复作用比较有利于糜棱岩中金的富集 ;由动态重结晶石英颗粒统计的差异古应力显示变形强度与Au富集有显著的正相关性 ,相关系数达 +0 .5 92 8。动力变形不同阶段形成的石英矿物其微量元素含量明显不同 ,石英中流体包裹体的成分也有明显的差异 ,反映出不同动力变形阶段流体活动的差异性与金富集密切相关。构造地球化学模拟试验表明 ,变形作用不仅导致岩石组构的变化 ,形成微型剪切带、碎粒流带等流动构造 ,而且伴随有明显的流体活动。这些过程与压溶作用密切相关 ;另外 ,动力作用中伴随着金的沉淀、富集 ,这其中Si、Fe组分起了重要的作用。

DYNAMIC DEFORMATION RELATED ORE-FORMING PROCESS AND TECTONO-GEOCHEMICAL SIMULATING EXPERIMENTS OF ERJIA GOLD DEPOSIT, HAINAN PROVINCE

Erjia gold deposit, located in Hainan province, was closely related with Gezhen shear zone activity. In this paper, tectono-geochemical method and tectono-geochemical simulating experiments were applied to studying the relations of Gezhen shear zone activity and gold ore-forming process. Evidences show that dynamic deformation resulted in the deformation of migmatitic rock and the formation of mylonite, and in this process normally accompanied by tectonic fluid activity, variation in mineral compositions and chemical components can be observed. Several deformation mechanisms could be distinguished in the deformation of Gezhen shear zone, of which the resilience mechanism could benefit most for gold enrichment in mylonites. Differential paleogeometor from recrystallizied grain size of quartz testified a significant positive relation of deformation strength to Au enrichment; its correlation coefficient could be as high as +0.5928. Trace element abundances in quartz formed in different dynamic deformation stages varied greatly; chemical compounds of fluid inclusion formed in different stages also varied obviously, this indicates a closer relation between differentiations of tectonic fluid activity and gold enrichment. Results listed as follows could be observed in tectono-geochemical simulating experiments: texture of tested samples was altered due to dynamic deformation, micro-shear zone was formed where cataclastic grain flow and apparent fluid activity were accompanied. These phenomena are connected closely with pressure dissolution. Furthermore, gold enrichment and precipitation could be observed during deformation, and it is found that chemical elements Si and Fe played key roles in this process.