红土型金矿床的地质特征、成矿条件及找矿评价标志

GEOLOGICAL CHARACTERS, MINERALIZINGSETTING AND PROSPECTING CRITERIA OF LATERITE GOLD DEPOSIT

红土型金矿是８０年代新发现的金矿类型，它可分为初生型和改造型两类。矿床规模大，矿体成层状、似层状和透镜体，产状平缓。矿石呈松散状，品位低，金主要呈次显微状或微粒状的游离自然金存在，其沉淀富集主要发生在地下水流动带。形成红土型金矿的条件为：相对稳定的地质区及地台区，存在含金矿源体，古气候为热带雨林和热带稀树干草原气候，准平原及低山丘陵地貌，找矿评价标志为：发育红土型风化壳是找矿前提，金矿源体存在是找矿基础，化探异常、红土发育区残留的“硅帽”及红土化剖面中的铁质带为重要的找矿标志，网纹状红土下面的高岭土层为矿体顶板的标志层。

Laterite type gold deposit was a new type of gold deposits founded in 1980s, which can be classified into primary type and reformed type. Deposits occur as a large scale; their orebodies are as stratiform, stratoid form and lens with gentle occurrence;and their ores with low grade loose. Golds mainly occur as submicrostopic or microgranular free natural golds. Their sedimentation and enrichment were mainly occur in flow zone of underground water. The mineralizing setting for this type should be relatively stable shield and platform, the region where existed gold bearing source unit, the climate of tropical rain forest and dry glasslands with rare trees, the landforms of peneplain and low hills. The prospecting criteria include weathering lateritic crust, gold source unit, geochemical anomaly, residual “siliceous hat” in the laterite area and ferruginous belt in the cross section with laterization. The kaolin bed under patterned laterite is the indicator of the ore roof. Placer gold indicate that the laterite area in the upper reach was probably the indicator occurring laterite type gold deposit.