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A MISTAKE IN THE INTERPRETATION OF GAMMA LOG CURVE FOR THE STUDY OF VOLCANIC SEDIMENTARY ROCKS AND RELATED ORE DEPOSITS |
FENG Bao-hua |
Chinese Academy of Geological Sciences, Beijing 100037, China |
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Abstract Based on the natural gamma log curves of acid tuff and clay rocks of acid volcanic events, the author here queries the arguments that radioactive intensity of sedimentary strata will grow with the increasing argillaceous materials and that the natural gamma value and the empirical equation can be used to calculate contents of argillaceous materials. The natural gamma curve of acid tuff has high anomaly response, which can not be interpreted as the response of the mudstone. If we regard the gamma curve of high anomaly exclusively as anomaly of mudstone, the viewpoint is obviously one-sided. The gamma values of clay rocks of various volcanic events are different very considerably, and hence the utilization of the gamma values to calculate the contents of argillaceous materials is likely to result in remarkable errors. In the end of this paper, the author has explained in brief the gamma curve of the bauxite bed and discussed the prospects of the nuclear log.
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Received: 30 June 2007
Published: 24 April 2008
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