激发极化法探测断裂蚀变带型金矿

Application of induced polarization method to prospectingthe fracture alterated belts-type gold

断裂蚀变带型金矿主要受断裂带控制,同时含矿热液与断裂两侧围岩发生绢云母化、硅化等蚀变使得含矿热液中的黄铁矿合金产生沉淀.利用中间梯度激发极化法中的视电阻率ρs确定断层及蚀变带,利用视幅频率Fs确定蚀变体中黄铁矿化程度.对河北易县孔各庄金矿进行探测,结果表明:利用中间梯度激发极化法的视电阻率ρs可确定断层蚀变带的分布范围;利用视幅频率Fs能进一步区分断层两侧白云岩蚀变体中的黄铁矿矿化程度;利用ρs等值线分布规律可判断剖面内白云岩、蚀变白云岩及断层破碎带的存在部位及产状;根据Fs等值线的梯度变化和Fs等值线的形态可圈定含金黄铁矿化白云岩的赋存空间,间接探测金矿.

The fracture alterated belts-type gold deposit is controlled mostly by the fracture zone . Silicated alteration, sericited alteration and other type of alteration come into being because of interacting between the hydrothermal solution containing mine and the adjacent rock of rupture.These alterations cause the pyrite containing gold in the hydrothermal solution to deposit. Using Middle Gradient Instrument and Induced Polarization Method, some parameters, such as apparent resistivity(ρ_s) , apparent amplitude frequency (F_s ) can be gained. The apparent resistivity(ρ_s) can make certain the existing of the fault and of the alteration zone, and the amplitude (F_s ) can make sure of the salimity of the pyrite in the alteration object . The results of exploration indicate that the apparent resisticity(ρ_s) can confer the scope of the fault alteration zone, and the apparent frequency (F_s ) can distinguish the salimity of the pyrity in the alteration of dolomite between two sides of the fault .According to the distributing law of ρ_s contour in the value contour profiles, the position and the occurrence of alterated dolomite, and that of fracture zone can be figured out. According to the grades variety and the shape of F_s value contour profiles , the spatial forms of pryited-dolomite containing gold can be found out, and the gold deposit then can be explored indirectly.