冰碛扇型砂金矿床特征及其成矿初探

成生于冰碛扇内，经一定的生物、物理、化学成矿作用，以砂金形态分布而富集成矿的金矿称为冰碛扇型砂金矿床。它具有沿造山带一定标高范围成群、成带分布，沉积物为近源且半胶结，砂金呈面状分布，并以粒金、块金为主，具胶状、浑圆状、包块状构造形态，分布极不均匀等特征。冰碛扇型砂金矿床的成矿作用与河成砂金矿床有本质的区别。它的成矿作用模式是：造山带下地壳富含的活化金通过新构造运动活化的断裂运移地表，经地下流体和地表流体的迁移聚集到冰碛扇这一封闭稳定的生物、物理、化学障环境中，主要经高效聚金微生物有机胶体成矿作用沉淀、再生加大形成砂金，逐步富集成矿床。而红色磨拉石建造中风化离解的Ｆｅ，Ｍｎ物质对沉淀环境ｐＨ值起着一定的调节作用。冰碛扇型砂金矿床在我国西部造山带内广泛分布，具有一定的工业价值，是砂金矿床中一重要类型，应予以重视

THE PRELIMINARY STUDY OF FEATURE OF MORAINIC FAN TYPE GOLD BEARING PLACER AND ITS MINERALIZATION

The morainic fan type gold bearing placer is defined as the gold deposit of formed in the morainic fan by the certain biomineralization and physical chemical mineralization and distributed and enriched in the shape of placer gold. The feature of this type gold deposit is as follows:to distribute in group and in belt along a certain elevation of orogenic belt, semi cemented proximal sediments, the planar distribution of placer gold composed mainly by granular gold and nugget is extremely not even. The mineralization of morainic fan type gold bearing placer is distinct from that of stream placer deposit. The mineralization model of morainic fan type gold placer is that the activated gold in the lower crust of orogenic belt has been migrated to the surface by fault formed from new tectonic movement, then to congregate in the morainic fan with the enclosed and stable organism physical chemical barrier environments through the migration of underground fluid and surface fluid.The precipitation and palingenesis by the organo colloidal mineralization of high effective gold collecting microorganism formed the placer gold, and lastly,enriched progressively the gold deposit. The Fe Mn mass dissociated by weathering in the red molasse formation can partly adjust the pH of sedimentary environments. The morainic fan type placer gold has a wide distribution in the orogenic belt of West China and has a certain industrial value. It is one of the important type of gold bearing placer.