摘要
陕西双王金矿的含金钠长铁白云石角砾岩是秦岭钠长角砾岩带中典型的含金热液角砾岩,区域上受凤镇-山阳同生大断裂控制。本文对钠长岩及钠长角砾岩进行了锆石年代学和岩石地球化学研究,结果表明在绢云母板岩-钠长石化板岩-钠长角砾岩的岩性变化中,Na2O逐渐富集而K2O逐渐贫化,二者呈负相关关系,说明在蚀变过程中有钠的代入和钾的带出;REE的球粒陨石标准化配分模式相似,说明蚀变钠长岩与围岩具有继承性。双王钠长碳酸质角砾岩的形成不是单一的过程,而是经历了热水同生沉积、热液交代蚀变、液压致裂,热流体隐爆等成岩成矿方式的叠加作用。钠长角砾岩中锆石的SHRIMP年龄区间较大,423~513 Ma和808~1166 Ma是两个峰期,与南秦岭泥盆系沉积地层中的锆石峰值年龄相似;而角砾岩中最年轻的锆石年龄为280.1~277.5Ma,代表了隐爆角砾岩形成的时间下限。角砾岩的形成至少经历了3个阶段:(1)晚泥盆世拉分断陷盆地时的热水沉积阶段;(2)早石炭世(342Ma)凤太盆地构造反转,深源碱性热流体上涌形成热液交代蚀变和液压致裂;(3)早二叠世碱性钠质碳酸盐流体发生浅成隐爆并形成隐爆钠长碳酸质角砾岩。综上所述,双王钠长角砾岩为异时异相同位叠加,是具有多期多阶段叠加成岩成矿特征的热液角砾岩构造系统。
The gold-bearing albite-carbonate breccia in the Shuangwang gold deposit is one of typical goldbearing hydrothermal breccia bodies in the Qinling breccia belt,which is controlled by Fengzhen-Shanyang contemporaneous fault.This paper studied the zircon SHRIMP chronology and petrochemistry,founded that range from sericite slate to albitized slate and albitized breccia,Na2 O gradually enriched and K2 O gradually depleted,which is a negative correlation,indicating Na brought in and K took out in the ateration process.The formation of albite-carbonate breccia was not a single process but experienced hot-water Sedimentary,single component of hot water with the Syngenetic metasomatism,hydraulic fracturing,hot fluid crypto-explosion, hot fluid boiling, superimposed hydrothermal mineralization, supergenic metallogenesis and other diagenetic mineralization superposition.The range of ages from zircon SHRIMP dating of breccia is large,423 Ma^513 Ma and 808 Ma^1166 Ma are are two peaks,similar to zircon ages of Devonian sedimentary strata in South Qinling;the youngest zircon ages are 280.1 Ma^277.5 Ma,representing the lower limit of crypto-explosive breccia.The ore-bearing breccia has experienced three stages：（1）the late devonian,hot water sedimentary in Feng-tai pull-apart basin;（2）during EarlyCarboniferous（342 Ma）,feng-tai basin occured tectonic inversion,and hot alkaline hydrothermal fluid derived from deep earth upwelling,which formed metasomatic alteration and hydraulic breccia;（3）the early-Permian,alkaline carbonate fluid occurred crypto-explosion and the formed crypto-explosive breccia.According to the studies,the hydrothermal breccia tectonic system were characteristics of multi-phase and multi-stage superimposed diagenetic.
作者
范玉须
方维萱
李廷栋
肖庆辉
郭玉乾
FAN Yuxu;FANG Weixuan;LI Tingdong;XIAO Qinghui;GUO Yuqian(The Chinese Academy of Geological Sciences,Institute of Geology,Beijing,100037;China University of Geosciences（Beijing）,Beijing,100083;China Non ferrous Metal Resource Geological Survey,Beijing,100012)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2018年第9期1873-1887,共15页
Acta Geologica Sinica
基金
国家自然科学基金项目"西秦岭卡林-类卡林型金矿床的成矿地质背景与叠加成矿作用研究(41030423)"资助成果
