微细浸染型金矿床的稳定同位素特征与成因探讨

对我国众多沉积岩系中的微细当染型金矿床开展了较为系统的稳定同位素地球化学研究，非常分散复杂的氢氧同位素组成被认为是沉积盆地流体的一个典型特征，这是因为盆地流体中水的两个主要来源－海水和大气降水，经不同程度的水－岩反应同位素交换后又以不同比例相互混合，再加上有机物和粘土矿物的相变水在不同阶段以不同比例加入。

STABLE ISOTOPE COMPOSITIONS OF MICRO-DISSEMINATED GOLD AND GENETIC DISCUSSION

In Southwest China, over hundred ore deposits and occurrences of sedimenthosted micro- disseminated gold were discovered during the last two decades. A systematical research on stable isotope geochemistry of the ores and their hostrocks have been carried out. Very complex and scattered isotopic compositions of oxygen and hydrogen are probably typical for basin derived fluid, because it was derived from fluid- containing sediments of various sources, and it has experienced a long- term isotopic exchange with rocks and organic matters. Carbon and oxygen isotopes of calcite in the ores and their hostrocks indicate that CO2 in was produced mainly by dissolution of marine carbonates. Sulfur isotope composition of sulfides in the ores and their hostrocks exhbits the same characteristics of sedimentation- diagenesis derived H2S. Lead isotope composition shows a source of upper-crust or orogenic belt. It is gold-organic complexes that have probably resulted in gold mobilization from sediments and then transportation in basin fluids.