金堆城超大型钼矿床水-岩δD-δ~(18)O同位素交换体系理论模型及成矿流体来源

基于水-岩δD-δ18O同位素交换体系理论模型的建立和计算，对金堆城超大型斑岩钼矿四个不同成矿期中成矿流体的演化和来源进行了研究，发现在成矿前期和早期，成矿流体为岩浆水与围岩在较低水／岩比值（0．1W／R＞0．001）和中、高温（t=250～500℃）条件下反应后的残余流体，而主成矿期和成矿晚期的成矿流作为大气降水在相对较高水／岩比值（0．5＞W／R0．1）和中、低温（t＝150～310℃）条件下与围岩反应后的残留流体。大气降水在金堆城钼矿成矿过程中起了重要作用。在主成矿期水／岩比值达到最高。

THEORETICAL MODELLING OF WATER-ROCK δD-δ~(18)O ISOTOPIC EXCHANGE SYSTEM AND SOURCE OF OREFORMING FLUID: A CASE STUDY ON JINDUICHENG SUPERLARGE-SCALE MOLYBDENUM DEPOSIT, CENTRAL CHINA

Based on theoretical modelling and calculation of water-rock δD-δ18O isotopic exchange process,the evolution and sources of ore-forming fluid in four metallogenic epochs of the Jinduicheng superlarge-scale porphyry-type molybdenum deposit were investigated. It was revealed that in the pre-metallogenic and early-metallogenic epochs, the ore-forming fluid was a residual fluid derived from magmatic water-wall rock interaction under lower W/R ratios (0. 1≥W/R > 0. 001 ) and moderate to high temperature (T = 250 - 500℃ ), while in the metallogenic and post-metallogenic epochs, the oreforming fluid was a residual fluid derived from meteoric water-wall rock interaction under relatively higher W/R ratios (0. 5 >W/R≥0. 1 ) and moderate to lower temperature (T = 150 - 310℃). The meteoric water played an important role in molybdenum mineralization, and at the metallogenic epoch the W/R ratio reached its maximum value.