高雅宁　杨兴科　韩珂　吴旭　樊培贺

摘 要：南秦岭汉阴北部金斗坡矿区志留系梅子垭组面理以 S2 面理为主。大比例尺构造-岩相填图和剖面实测所获得的大量 S2 面理产状数据显示，S2 面理倾向305°～355°，倾角为25°～50°，为稳定北倾的平直面理。通过 S2 面理产状数据连图和综合分析，S2 面理与金矿化具有相同的展布特征及变化规律，对成矿具有制约作用。此外，选取梅子垭组含石榴石黑云母变斑晶绢云母石英片岩中的共生矿物石榴石-黑云母进行电子探针测试，运用Holdaway石榴石-黑云母地质温度计方法，估算出该区热蚀变温度为590 ℃～670 ℃。综合研究表明，印支晚期—燕山早期为金矿的成矿期，在此期间岩浆热液的强烈活动引起热蚀变作用的发生，生成石榴石与黑云母变斑晶；热变质作用促使Au元素发生活化，有利于后期Au元素富集成矿。

关键词：S2 面理；控矿要素；金矿；梅子垭组；石榴石-黑云母地质温度计；汉阴地区；南秦岭

中图分类号：P612 文献标志码：A

Abstract： The foliation of Silurian Meiziya Group in Jindoupo ore area of the northern Hanyin， South Qinling is mostly S2 foliation. The massive occurrence data from mapping as well as section plane based on large measuring scale indicate that the tendency of S2 foliation are 305°-355° with the dip angle of 25°-50°； the S2 foliation， which inclines towards the north， is stable as well as placid. After comprehensive mapping and analysis， the distribution direction of S2 foliation is mainly the same as that of gold mineralization， and has obvious constraint on mineralization. In addition， after testing the biotite-garnet paragenetic mineral assemblage from garnet-bearing biotite metacrysta sericite-schist of Meiziya Group by electron probe microanalysis， the thermal alteration temperature （590 ℃-670 ℃） was estimated by the means of Holdaway biotite-garnet geothermometer method. Comprehensive study indicates that Late Indosinian-Early Yanshanian is the metallogenic period of Au deposit， and the intense magmatic hydrothermal activities cause hydrothermal alteration and give birth to biotite metacrysta as well as garnet； the thermometamorphism accelerates the activity of Au， which has the advantage of later mineralization.

Key words： S2 foliation； factor of ore-control； gold deposit； Meiziya Group； garnet-biotite geothermometer； Hanyin area； South Qinling

0 引 言

南秦岭汉阴北部金矿田东西长约50 km，南北宽10～20 km，区内自北向南依次分布有金斗坡、黄龙、铁佛寺、长沟、鹿鸣、吴家湾等规模不等的金矿床（点）。前人对南秦岭地区很早就已开展地质研究，从区域构造发展演化、岩石组合特征以及地质构造格局到矿产资源勘查方面积累了丰富的资料并取得了大量成果[1-15]。研究表明，汉阴北部所产出的金矿床均赋存于下志留统梅子垭组的各个岩性段中，其成矿特征又普遍受区域性一系列脆-韧性剪切带控制，因此，矿田内各金矿床（点）在矿化特征、成矿构造及成矿模式上均具有一定的相似性[1-7]。……