『Abstract
Empirical evidence indicates that processes affecting number
and quantity of resources in geologic setting are very general
across deposit types. Sizes of permissive tracts that geologically
could contain the deposits are excellent predictors of numbers
of deposits. In addition, total ore tonnage of mineral deposits
of s particular type in a tract is proportional to the type's
median tonnage in a tract. Regressions using size of permissive
tracts and median tonnage allow estimation of number of deposits
and of total tonnage of mineralization. These powerful estimators,
based on 10 different deposit types from 109 permissive worldwide
control tracts, generalize across deposit types. Estimates of
number of deposits and of total tonnage of mineral deposits are
made by regressing permissive area, and mean (in logs) tons in
deposits of the type, against number of deposits and total tonnage
of deposits in the tract for the 50th percentile estimates. The
regression equations (R2 = 0.91 and 0.95) can be used
for all deposit types just by inserting logarithmic values of
permissive area in square kilometers, and mean tons in deposits
in millions of metric tons. The regression equations provide estimates
at the 50th percentile, and other equations are provided for 90％
confidence limits for lower estimates and 10％ confidence limits
for upper estimates of number of deposits and total tonnage. Equations
for these percentile estimates along with expected value estimates
are presented here along with comparisons with independent expert
estimates. Also provided are the equations for correcting for
the known well-explored deposits in a tract. These deposit-density
models require internally consistent grade and tonnage models
and delineations for arriving at unbiased estimates
Key Words: Quantitative mineral resource assessment; Undiscovered
resources; mineral deposit density』
Introduction
Number of deposits estimates
Tonnage estimates
Conclusions
References