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N.J. Bridges

Publications and source records attributed to N.J. Bridges.

6 recordsLinked to original sources
USGS1994

An integrated data-directed numerical method for estimating the undiscovered mineral endowment in a region

An integrated data-directed numerical method has been developed to estimate the undiscovered mineral endowment within a given area. The method has been used to estimate the undiscovered uranium endowment in the San Juan Basin, New Mexico, U.S.A. The favorability of uranium concentration was evaluated in each of 2,068 cells defined within the Basin. Favorability was based on the correlated similarity of the geologic characteristics of each cell to the geologic characteristics of five area-related deposit models. Estimates of the undiscovered endowment for each cell were categorized according to deposit type, depth, and cutoff grade. The method can be applied to any mineral or energy commodity provided that the data collected reflect discovered endowment. ?? 1994 Oxford University Press.

Nonrenewable Resources↗
USGS1986

Quantitative estimation of undiscovered mineral resources: A case study of US Forest Service Wilderness tracts in the Pacific Mountain system

The need by land managers and planners for more quantitative measures of mineral values has prompted scientists at the U.S. Geological Survey to test a probabilistic method of mineral resource assessment on a portion of the wilderness lands that have been studied by the Survey during the past 20 years. A quantitative estimate of undiscovered mineral resources is made by linking the techniques of subjective estimation, geologic mineral deposit models, and Monte Carlo simulation. The study, which uses grade-tonnage and occurrence models for 21 geologic deposit types, considers 91 U.S. Forest Service wilderness tracts in California, Nevada, Oregon, and Washington. Estimates of the amounts of the 11 metals contained in undiscovered mineral deposits of the types studied range from negligible to several years of U.S. consumption. Although these estimates are limited to metals contained in undiscovered deposits of a small number of metallic mineral deposit types, the assessment procedure can be expanded by the use of additional deposit models and by using information about identified mineral resources. This will allow models of economic processes such as exploration, development, and production to be applied.

Economic Geology↗
USGS1985

PREPRO: a computer program for encoding regional exploration data for use in characteristic analysis

The preprocessor (PREPRO) computer program offers the exploration geologist a variety of options for encoding regional exploration data into ternary form for use in characteristic analysis. PREPRO's options include variable-input formats, cursor input, ordering among a set of input variables, and selectable ternary transformations. Moreover, the program provides for the display of results which, in turn, makes possible review, reselection, and retransformation of variables. Most important, the performance of the listed steps in an interactive computing environment results in rapid and efficient preprocessing of the data.

Computers & Geosciences↗
USGS1980

Discrim: a computer program using an interactive approach to dissect a mixture of normal or lognormal distributions

DISCRIM is an interactive computer graphics program that dissects mixtures of normal or lognormal distributions. The program was written in an effort to obtain a more satisfactory solution to the dissection problem than that offered by a graphical or numerical approach alone. It combines graphic and analytic techniques using a Tektronix1 terminal in a time-share computing environment. The main program and subroutines were written in the FORTRAN language. ?? 1980.

Computers & Geosciences↗