湘东北雁林寺金矿构造控矿特征及金成矿ESR测年

针对湘东北雁林寺地区金矿是否存在矿源层、NE向劈理化带和NW向韧性剪切带对金矿的控制作用及其成矿时代等争议性问题进行野外调查和室内分析,研究结果表明:(1)金矿的矿源层是存在的,矿源层为中元古界冷家溪群;(2)NE向劈理化带和NW向韧性剪切带是该区金矿的主要控矿构造;(3)石英脉ESR测年结果表明,NE向金矿脉成矿年龄为214.2Ma,为第一期成矿,形成于印支晚期。NW向金矿脉成矿年龄为177.4～155.0Ma,为第二期成矿,发生在燕山早期。

Structural Ore-Controlling Characteristics and Electron Spin Resonance Dating of the Yanlinsi Gold Deposit in Northeastern Hunan Province

Yanlinsi gold deposit is a middle size deposit occurring in northeastern Hunan Province, hosted by the Lengjiaxi Group. Although it has been mined for 20 years, its metallogenic mechanism is still in dispute. The aim of this paper is mainly to address the existence of ore source bed, controls of the NE-trending cleavage belt and NW-trending ductile shear zone on the distribution of the gold bearing quartz veins, and also the metallogenic epoch. Based on field survey and lab analysis, the authors get the following results. The Mesoproterozoic Lengjiaxi Group is the source bed. The ore controlling structures are mainly NE-trending cleavage belt and NW-trending ductile shear zone. ESR dating of the quartz veins shows that metallogenic age of the NE-trending gold-bearing quartz vein is 214.2 Ma, belonging to Late Indosinian, whereas, the NW-trending gold-bearing quartz vein is 177.4~155.0 Ma, belonging to Early Yanshanian. Since Caledonian, Yanlinsi area underwent strong structural compression, deep fluid migrating from thrust zone to cleavage belt via structural fissures, extracting Au from the source bed, and eventually, forming the first phase NE-trending gold ore body. At Early Yanshanian epoch, Yanlinsi area underwent NNE-trending strike slip, associating NW-trending R′type ductile shear zone, mylonitization and schistositized of rocks possibly formed space for hydrothermal activity which could lead to gold mineralization, generating second-phase NW-trending gold ore body.