铜陵桃园铁帽型金矿床氧化带与金的赋存特征

FEATURES OF OXIDATION ZONE AND GOLD OCCURRENCE IN GOSSAN TYPE GOLD DEPOSIT AT TAOYUAN, ANHUI

桃园铁帽型金矿产于似层状硫铁矿体倾斜上端.由于上下为不透水层,以化学风化为主.适宜的沉积环境等因素,形成次生含金富集带.富集区为两头高、中间低的山前凹槽或铁帽底板的舒缓部位.金随褐铁矿凝胶充填淋失多孔状矿石中或石英裂隙里.以自然金、银金矿为主,金与褐铁矿、锰矿物、重晶石、石英等密切共生,在氧化、还原环境频繁交替下,使金粒不断生长与再溶融、再加大而富集的.

Taoyuan gossan type gold deposit occurs at the upper end of the slant layered pyrite ore body. The second gold enrichment zone is located between impervious beds and formed dominantly by chemical weathering in the favourable environment. Good ore is found in the depressions in front of hills or at the gentle places of the footwall of gossans. Gold is filled together with gelatinous Fe (OH)_3 in leached porous rocks and micro fractures in quartz, occuring as native gold and electrum which are associated with limonite, Mn - minerals, barite and quartz. Alternating oxidation and reduction lead to growth, resolution, regowth and enlargement, then to the concentration of gold grains.