摘要
嘎拉金矿床位于甘孜-理塘结合带北段,矿区内韧性剪切变形特征明显,主要赋矿地层为上三叠统曲嘎寺组蛇绿混杂岩,控矿构造以北西向断裂为主。论文对与成矿有关的热液石英及其中的流体包裹体、各类硫化物进行了H-O-C-S-Pb同位素分析,测试显示石英δ18OQ的值介于15.60‰～18.38‰之间,流体的δ18OH2O值介于8.24‰～9.89‰,而δDH2O值为-121.342‰～-126.368‰;流体包裹体中CO2的δ13C值介于-11.3‰～-2.1‰之间;各类矿石硫化物δ34S值介于-9.2‰～-4.9‰,峰值集中在-7‰～-5‰;铅同位素显示铀铅富集的特征。同位素研究表明成矿热液来源于变质水,并有大气降水的参与;金等成矿物质主要来自于围岩地层。年代学数据表明嘎拉金矿床形成于燕山晚期,是在义敦岛弧碰撞造山过程中由挤压作用体制转变为伸展作用体制的构造背景下形成的造山型金矿床。
The Gala gold deposit is located in the northern Ganzi-Litang suture zone. There is obvious ductile shear deformation in the ore district. The ore bodies are mainly hosted in the ophiolite mixite of Upper Triassic Qugasi Formation and controlled by the NW-trending faults. In this paper, we analyzed the H-O-C isotopic composition of the quartz and ore-forming fluid and S-Pb isotopic composition of the sulfides from different ores in the Gala gold deposit. The δ18OQ values changed from 15.60‰ to 18.38‰, and the δ18OH2O values vary between 8.24‰ and 9.89‰, with the δDH2O values ranging between -121.342‰ and -126.368‰. The δ13CCO2 values of ore fluids are between -11.3‰ and -2.1‰. The δ34S values range from -9.2‰ to -4.9‰, with peaks ranging from -7‰ to -5‰. The ores are rich in U-radiogenic Pb. The studies on isotope systematics indicate that the ore fluids forming the Gala gold deposit were probably initially sourced from a process of metamorphic devolatilization, and gradually mixed with meteoric water; the ore-forming elements were mainly derived from the wallrock. The available K-Ar and Rb-Sr ages indicate that the ore-forming process mainly took place in Late Yanshanian, during the transition geodynamic setting from collisional compression to extension in the collisional process of the Yidun arc orogen, Sanjiang region. The Gala deposit can be determined as an orogenic-type gold deposit.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第4期1347-1357,共11页
Acta Petrologica Sinica
基金
国家重点基础研究发展规划项目(2009CB421006)
国家自然科学基金项目(41030423)
北京市优秀博士学位论文指导老师科研项目(20111141501)
中央高校基本科研业务费专项资金(2010ZD11)
中国地质大学地质过程与矿产资源国家重点实验室开放基金联合资助
