Probabilistic Estimates of Number of Undiscovered Deposits and Their Total Tonnages in Permissive Tracts Using Deposit Densities |
| |
| Authors: | Donald A Singer Ryoichi Kouda |
| |
| Institution: | (1) U.S. Geological Survey, Mail Stop 901, 345 Middlefield Road, Menlo Park, CA 94025, USA;(2) AIST, Tsukuba, Japan |
| |
| Abstract: | Empirical evidence indicates that processes affecting number and quantity of resources in geologic settings 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 a 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 (R
2 = 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. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
