柴北缘鱼卡榴辉岩型金红石矿床成矿物理条件  

An analysis of metallogenic physical conditions of the Yuqia eclogite-type rutile depositin the North Qaidam

作　　者：林成贵 郑有业 程志中[1] 许荣科[4] 陈鑫[3] LIN Chenggui;ZHENG Youye;CHENG Zhizhong;XU Rongke;CHEN Xin(Development and Research Center of China Geological Survey,Beijing 100037,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Faculty of Earth Resources,China University of Geosciences,Wuhan 430074,Hubei,China;Institute of Geological Survey,China University of Geosciences,Wuhan 430074,Hubei,China)

机构地区：[1]中国地质调查局发展研究中心,北京100037 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]中国地质大学(武汉)资源学院,湖北武汉430074 [4]中国地质大学(武汉)地质调查研究院,湖北武汉430074

出　　处：《地质通报》2019年第5期866-883,共18页Geological Bulletin of China

基　　金：国家重点研发计划《深部矿产资源三维找矿预测评价示范》(编号:2017YFC0601506);中国地质调查局项目《青海省大柴旦镇绿梁山-双口山多金属矿调查评价》(编号:12120113032800)

摘　　要：鱼卡榴辉岩型金红石矿床位于柴北缘超高压变质带西侧,是青藏高原发现的第一个超大型金红石矿床。为研究该矿床的控矿因素和成矿机制,在详细的野外地质调查和岩相学研究的基础上,利用电子探针对该矿床榴辉岩中的各特征矿物进行分析。研究表明,粗粒块状高钛榴辉岩的石榴子石保存了较完整的成分环带,从核部到边部,石榴子石的化学成分、矿物包裹体的种类和粒度都具有明显的分带性;细粒片麻状低钛榴辉岩的矿物颗粒较小,石榴子石的成分环带较差。鱼卡榴辉岩的p-T演化特征反映,它们经历了深俯冲阶段的升温升压到早期折返阶段的升温降压,再到之后的降温降压的顺时针演化轨迹。榴辉岩中进变质矿物组合和生长环带的保存说明,榴辉岩的形成经历了相对快速俯冲和折返的动力学过程,钛成矿作用时金红石很少发生转变。超高压变质前后为金红石最主要的成矿期。The Yuqia eclogite-type rutile deposit is located on the west side of the northern margin of the Qaidam Basin UHP metamorphic belt. And it is the first ultra-large rutile deposit found on the Tibetan Plateau. In order to study the ore-controlling factors and metallogenic mechanism of this deposit, the authors conducted detailed field geological survey and petrographic study. The characteristic minerals in the eclogite of the deposit were analyzed by electron microprobe analysis. It is shown that the garnets of coarse-grained high-Ti eclogite have preserved relatively complete compositional zoning;from the core to the edge, the garnet has a distinct zonality in chemical composition, type and granularity of mineral inclusions. However, the mineral particles in the fine and gneiss low-Ti eclogite are smaller, and the composition of the garnet is poor. Characteristics of p-T evolution of Yuqia eclogite show that it experienced a clockwise evolutionary trajectory from the temperature and pressure rise of the deep subduction stage to the temperature rise and pressure decrease of the early exhumation stage and then to the decrease of both temperature and pressure. The eclogite belongs to the metamorphic mineral assemblage with the preservation of the growth zone, which suggests that the formation of eclogites went through a dynamic process of relatively rapid subduction and reentry exhumation.

关 键 词：成矿条件 金红石矿床 榴辉岩 鱼卡 柴北缘 

分 类 号：P578.47[天文地球—矿物学]