摘要
为探讨德兴铜厂斑岩铜矿床成矿热液流体的来源、作用范围、时空演化及Cu在热液流体中的行为和迁移方向等重要问题 ,对采集于该矿床南部不同蚀变程度的岩石进行了氧、锶、钕同位素分析。结果表明 ,虽然与铜厂斑岩铜矿成矿过程有关的热液流体至少有 3种 ,包括高温岩浆流体、来自深部围岩的非岩浆流体和大气降水 ,但是起主导作用的是岩浆流体。钕、锶同位素在空间上的变化表明 ,在成矿流体形成及演化过程中 ,锶同位素值由斑岩体内部向围岩接触带有规律地升高 (0 .70 5→ 0 .711) ,指示了矿床是因热液流体将成矿元素从岩体内部迁移到接触带附近富集而成的 ,它符合斑岩铜矿的正岩浆模式。而钕同位素则相对稳定 。
To understand the sources, evolution process and transportation behavior of ore_forming fluids in the Tongchang porphyry copper orefield, Dexing County, the authors have studied such independent isotopic compositions as oxygen, strontium and neodymium in altered rocks from the southern part of the Tongchange deposit. According to oxygen and strontium isotope variations in the Tongchang porphyry system, at least three types of hydrothermal fluids were detected: the magmatic fluid, the deep_seated nonmagmatic fluid and the meteoric water. The magmatic fluid played a decisive role in the ore_forming process. Spatial Sr and Nd isotopic variation shows a gradual increase of Sr isotopic composition from the interior to the contact zone within Tongchang porphyry body (from 0.705 to 0.711), which suggests that the ore_forming elements including copper were transported by hydrothermal fluids from parent magma upwards and along the contact zone with the wall rocks, forming ores along the contact zone and in the shallow portion of the porphyry cupola. This accords with the model of orthomagmatic genesis for porphyry copper deposit. Nd isotope composition, however, is relatively stable during the hydrothermal fluid_rock interaction, and hence can serve as a tracer for magmatic origin of ore_forming fluids.
出处
《矿床地质》
CAS
CSCD
北大核心
2002年第4期341-349,共9页
Mineral Deposits
基金
国家自然科学基金 (编号 :4973 3 12 0
40 0 0 3 0 0 1)
中国博士后基金资助
关键词
地球化学
斑岩铜矿床
成矿过程
热液流体
示踪
氧
锶
钕同位素
成矿元素
geochemistry, porphyry copper deposit, O, Sr, Nd isotopes, ore_forming process, hydro_ thermal fluid, tracer
