The lognormal distribution of metal resources in mineral deposits

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• 作者：Donald A. Singer
• 关键词：Mineral deposit model ; Power law ; Grade and tonnage models ; Monte Carlo simulation ; Mineral resource assessments
• 刊名：Ore Geology Reviews
• 出版年：2013
• 出版时间：November, 2013
• 年：2013
• 卷：55
• 期：Complete
• 页码：80-86
• 全文大小：327 K

文摘

For national or global resource estimation of frequencies of metals a lognormal distribution has sometimes been assumed but never adequately tested. Tests of frequencies of Cu, Zn, Pb, Ag, Au, Mo, Re, Ni, Co, Nb₂O₃, REE₂O₃, Cr₂O₃, Pt, Pd, Ir, Rh, and Ru, contents in over 3000 well-explored mineral deposits display a poor fit to the lognormal distribution. Neither a lognormal distribution nor a power law is an adequate model of the metal contents across all deposits. When these metals are grouped into 28 geologically defined deposit types, only nine of the over 100 tests fail to be fit by the lognormal distribution, and most of those failures are in two deposit types suggesting problems with those types. Significant deviations from lognormal distributions of most metals when ignoring deposit types demonstrate that there is not a global lognormal or power law equation for these metals. Mean and standard deviation estimates of each metal within deposit types provide a basis for modeling undiscovered resources. When tracts of land permissive for specific deposit types are delineated, deposit density estimates and contained metal statistics can be used in Monte Carlo simulations to estimate total amounts of undiscovered metals with associated explicit uncertainties as demonstrated for undiscovered porphyry copper deposits in the Tibetan Plateau of China.