地史中成矿演化的趋势和阶段性

大量的地质矿产资料表明，随着地球的形成和发展，尤其是水圈、大气圈和生物圈的演化，成矿作用也呈前进的、不可逆的发展趋势，表现在成矿物质（矿种）由少到多；矿床类型由简到繁；成矿频率由低到高；聚矿能力由弱到强。受地球上重大地质事件的制约，这一成矿演化过程又表现出阶段性，可划分出７个成矿大阶段，即太古宙、古元古代、中元古代、新元古代、早古生代、晚古生代—早中生代、晚中生代—新生代等成矿期。每一期中都有特定的成矿构造环境和矿床成因类型。制约地史上成矿演化的主要因素有：①成矿物质的地球化学性质；②水圈、大气圈和生物圈的演化；③地球构造运动的演变。矿床形成后的保存条件对矿床的时空分布特征也有重要影响。

METALLOGENIC EVOLUTION AND MEGASTAGES IN EARTH′S HISTORY

Numerous geological data indicate that the metallogenic evolution in Earth's history shows as a progressive, irreversible process. With the lapse of time in Earth's history, the ore forming substances increased from a few kinds to many kinds, the ore types changed from simple to complex, the ore forming frequency varied from low to high and the ore forming capacity transformed from little to great. The whole metallogenic history in Earth can be divided into seven megastages with significant differences in ore forming characteristics. They are the Archean, the Early Proterozoic, the Middle Proterozoic, the Late Proterozoic, the Early Palaeozoic, the Late Palaeozoic Early Mesozoic and the Late Mesozoic Cenozoic ore forming megastages. In each megastage, there exist different ore forming tectonic settings and ore types respectively. The main controlling factors for the metallogenic evolution are: 1) geochemical features of ore forming substances; 2) the evolution of hydrosphere, atmosphere and biosphere and 3) the geotectonic movement. The preservative conditions of ore deposits also have great influence over the space temporal distribution of ore deposits.