区域生物成矿系统中分子化石来源的复杂性

在由单个热液金属矿床的生物——有机质成矿作用研究向区域生物——有机质成矿系统深入的今天,分子化石的重要性和复杂性日益显得突出。热液金属矿床成矿带往往属于有机质的过成熟区,分子化石的存在首先要考虑成矿后迁入事件的叠加,从中排除某些生物成矿作用假象,如川甘陕金三角区。除了最常见的吸附有机质外,晶包有机质可以是有机质过成熟的金属成矿区分子化石的一种不可忽视的新来源,可提供流体源或矿源的信息,如长江中下游多金属成矿区。赋矿岩与蚀变岩之间的某些分子化石差异则蕴含着与成矿有关的诸如还原作用等化学反应信息,如长江中下游多金属成矿区。

COMPLICATED ORIGINS OF MOLECULAR FOSSILS INVOLVED IN REGIONAL BIOMETALLOGENETIC SYSTEM

Molecular fossils identified from the individual mineral deposits displayed a complicated origin, which had a wide application in the regional biometallogenesis. Molecular fossils, occurring in some metallogenic regions such as the Sichuan Gansu Shaanxi gold triangle area where the organic matter was of super maturity, were believed to be partly introduced into the deposits after the metallogenesis event. In addition to the common adsorptive organics, the bound organic matter enclosed in source rocks could be an important source for molecular fossils identified in the super mature region, for example, the polymetallic belt of Lower Middle Yangtze area. The related metallogenesis in one deposit could be inferred from the difference of molecular fossils between ores and wall rocks, and between host rocks and altered rocks.