西藏尼雄矿田滚纠铁矿花岗闪长岩成因的矿物化学证据  

Genesis of Granodiorite in the Gunjiu Iron Deposit of the Nixiong Ore-field, Tibet: Evidence from Mineral Chemistry

作　　者：于玉帅[1,2,3] 杨竹森[4] 高原 刘英超[6] 田世洪[4] 纪现华[7] 

机构地区：[1]武汉地质矿产研究所,湖北武汉430205 [2]中国地质调查局花岗岩成岩成矿地质研究中心,湖北武汉430205 [3]东华理工大学核资源与环境教育部重点实验室,江西南昌330013 [4]中国地质科学院矿产资源研究所,北京100037 [5]江西省地质调查院,江西南昌330201 [6]中国地质科学院地质研究所,北京100037 [7]中国地质大学地球科学与资源学院,北京100083

出　　处：《地质与勘探》2013年第5期897-906,共10页Geology and Exploration

基　　金："十一五"国家科技支撑计划项目(2006BAB01A04);国家重点基础研究发展计划973项目(2011CB403100和2009CB421007);地质调查计划项目(1212010918014);国际地质对比计划(IGCP-600);东华理工大学核资源与环境教育部重点实验室开放基金项目(NRE1206)联合资助

摘　　要：西藏尼雄矿田是冈底斯措勤-申扎铁铜多金属成矿带的重要组成部分。滚纠铁矿是尼雄矿田铁成矿作用的典型代表,其中花岗闪长岩和二长花岗岩与成矿作用关系密切。本文从矿物学角度入手,在详细薄片鉴定基础上,对花岗闪长岩中角闪石和黑云母进行电子探针化学成分分析,进而恢复岩浆源区性质、揭示岩浆侵位结晶的物理化学条件,探索岩浆热液体系与成矿作用之间的内在联系。电子探针成分分析显示角闪石贫Ti,富Mg,属镁角闪石;黑云母富Mg,为镁质黑云母,是典型的岩浆黑云母;角闪石和黑云母中F含量较高,分别为0.33和0.53。分析结果指示花岗闪长岩为钙碱性I型花岗岩,岩浆源区具有壳幔混源的特点,形成于高温630～680℃、高氧逸度logf O2=-14～-16和1.5×108～3.0×108Pa的压力条件下。The Nixiong ore-field is an important part of Coqin-Shenzha iron and copper metallogenic belt. The Gunjiu iron deposit is a typical repre- sentative of the Nixiong ore-field. The granodiorite and monzogranite in this deposit are associated with iron mineralization. In order to discuss the source, characteristics of the magma and to reveal the physical, chemical conditions in the process of magma emplacement and crystallization, this work has made detailed mineralogical identification and electron microprobe analyses of minerals fi＇om granodiorite. The results show that the granodiorite is mainly com- posed of plagioelase, potassium feldspar, quartz, amphibole, biotite and few accessory minerals. Electron microprobe analyses indicate that the amphibole which is poor in titanium but rich in magnesium is attributed to magnesiohornblende. The biotite belonging to magnesian biotite is of magmatic genesis. The analysis shows that the granodiorite belongs to calc-alkaline I-type granite, and granodiorite was formed from a mixed magma between the partial inch- ing materials of the crust and asthenospheric mantle in late Early Cretaceous. According to the chemical composition amphibole and biotite, the granodior- ite crystallization occurred under the conditions of high oxygen fugacity about logfo2 = - 14 ~ - 16, high temperature of 630 ~ 680~C and press of 1.5 x 10s -3.0 x 10Spa.

关 键 词：成因矿物学 花岗闪长岩 滚纠铁矿 尼雄矿田 西藏 

分 类 号：P575.1[天文地球—矿物学] P581[天文地球—地质学]