西藏冈底斯朱诺斑岩型铜矿床成矿流体特征

发布时间：2018-05-26 01:47

  本文选题：流体包裹体 + H-O同位素　； 参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：冈底斯是我国重要的斑岩型铜矿带,东段已发现一系列大型-超大型斑岩矿床且研究程度较高,而西段仅发现朱诺一例大型斑岩铜矿床,且研究程度较低,这不利于冈底斯东西段的对比研究。本文对朱诺矿床进行了流体包裹体岩相学研究、包裹体测温及激光拉曼光谱分析,并与冈底斯东段的驱龙斑岩矿床开展了对比。研究表明朱诺矿床共发育四种类型包裹体,分别为富液相气液两相水溶液包裹体(LV)、富气相气液两相水溶液包裹体(VL)、含子晶多相(LVH)及富CO2三相(C)包裹体。从成矿早期到晚期(即由A脉向B脉至D脉阶段),包裹体均一温度集中分布在350-550℃、250-350℃、250-300℃,盐度为5%-55%NaCleqv、5%-40%NaCleqv、2%-10%NaCleqv,显示包裹体均一温度及盐度呈递减趋势。而在B脉阶段,在显微镜下同一视域内可见不同类型(LV、VL、LVH)的包裹体共存,并且具有相似的均一温度而盐度变化较大特征,这是流体沸腾的明显标志,预示压力的降低及硫化物的沉淀。通过压力估算得到朱诺矿床A、B、D脉阶段的成矿深度分别为2.9km、2.7 km、2.3 km。朱诺H-O同位素显示出明显的δ18O和δD亏损,这可能是水岩反应、岩浆去气和大气降水混入共同作用的结果。通过与驱龙铜矿的对比,朱诺矿床硬石膏发育相对较弱,预示成矿流体氧逸度相对驱龙矿床低,此外二者在包裹体类型、温度、盐度等方面相似,但朱诺的成矿深度比驱龙的略浅,这在冈底斯西段总体剥蚀程度相对东段低的背景下是利于矿床的寻找。
[Abstract]:Gangdis is an important porphyry copper deposit in China. A series of large and super-large porphyry deposits have been found in the eastern part of China, and the study is relatively high, while only one large porphyry copper deposit has been discovered in the western section, and the degree of study is relatively low. This is not conducive to the comparative study of the east and west sections of Gundis. In this paper, the petrography of fluid inclusions, the temperature measurement of inclusions and the laser Raman spectroscopy of Juno ore deposits are studied and compared with those of the porphyry deposits in the eastern section of Gangdis. The results show that there are four types of inclusions in Juno deposit. They are liquid-rich gas-liquid two-phase aqueous inclusions, gas-rich gas-liquid two-phase aqueous solution inclusions, CO2 rich gas-liquid two-phase aqueous inclusions, sub-crystalline multiphase inclusions and CO2 rich three-phase aqueous inclusions. From the early metallogenic stage to the late stage (from vein A to vein B to vein D), the homogenization temperature of inclusions is concentrated in 350-550 鈩，

本文编号：1935470