Application of the Spectral Induced Polarization Method Over Some Mining Districts
Wu Zhixun, Luo Yanzhong, 1989. "Application of the Spectral Induced Polarization Method Over Some Mining Districts", An Overview of Exploration Geophysics in China — 1988, Zhao Jingxiang, Wang Yanjun, Fu Xuexin, Stanley H. Ward
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Both theoretical calculations and field case histories indicate that it is possible for the apparent time constant (τa) anomaly of a deep-seated orebody (or mineralization) to be detectable, while the other induced polarization (IP) parameters, such as apparent chargeability (ma), percent frequency effect (PFEa) or phase φa, barely reveal an anomaly. This is possible when there is a great difference between rock and ore in the time constant of the IP spectrum and an insignificant dilution of the apparent time constant τa. An integrated use of this parameter and other parameters of the spectrum in combination can result in differentiation of IP anomalies due to shallow sources.
The case history of the Fenglin copper deposit of Jiangxi Province reveals that the orebody and mineralization have the best response with the apparent time constant τa. In addition, the dilution effect on τa is smaller than the effect of the other parameters. Four types of IP parameters spectra for the Longtan carbonaceous formation of Permian age have been observed in the lower and middle reaches of the Yangtze River.
In the Chenzhuang iron deposit of northern Anhui province, the orebody and the mineralization belt, overlain by a low resistivity layer 100 m thick, are indicated by a distinct τa anomaly in the pseudosection. In the Panlonggang area of Jiangsu Province an enriched zone of dense-disseminated ores is distinguished from a large pyritized zone by using spectral IP parameters, mainly by the apparent time constant (ρa).