Persistent Link:
http://hdl.handle.net/10150/185146
Title:
An exploration-adjusted mineral occurrence model.
Author:
Wilson-Bahun, Tetevi.
Issue Date:
1990
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
A mathematical model describing the probability for n mines or prospects occurring within an elementary unit (cell) of an area has been referred to as an occurrence model. Estimation of parameters of occurrence models has been plagued by the effect of area delineation on the parameters. Moreover, incompleteness of exploration creates a bias in parameter estimates. This study proposes that when the model is to describe the probability for occurrence of mines or prospects, the appropriate area is a metallogenic unit of mining district scale. Accordingly, this study examined the delineation of area by successive expansion of a polygon seeking that size of area which provides the best fitting of a truncated and effort-adjusted exponential model. However, estimation of occurrence model parameters was found to be sensitive to location of polygon on the cluster. Consequently, this approach was abandoned in favour of geologically-defined metallogenic units referred to as Intrinsic Samples. Truncated and effort adjusted occurrence models were fitted to Intrinsic Samples which included the mining districts of the Walker Lake Quadrangle of Nevada and California. The estimated model for each metallogenic unit is used to estimate the gold-silver metal endowment of the unit. This represents a departure from previous studies, e.g. Allais, in which a single parameter estimate from a control area is used to estimate the mineral endowment in all parts of a large study area. Furthermore, the study addresses the issue of economic truncation of occurrence data used in exponential model construction. Because a metallogenic unit is less than completely explored, estimated parameters based on observed occurrences provide a biased description of the number of occurrences present (i.e. endowment). The transition from sample to endowment (population) parameter is achieved by parameterizing the exponential model for a metallogenic unit on exploration effort deployed in a unit area. Thus, fitting the model to observed data and evaluating it at infinite effort yields the model for gold and silver metal endowment in a metallogenic unit.
Type:
text; Dissertation-Reproduction (electronic)
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Mining and Geological Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Harris, DeVerle P.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleAn exploration-adjusted mineral occurrence model.en_US
dc.creatorWilson-Bahun, Tetevi.en_US
dc.contributor.authorWilson-Bahun, Tetevi.en_US
dc.date.issued1990en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractA mathematical model describing the probability for n mines or prospects occurring within an elementary unit (cell) of an area has been referred to as an occurrence model. Estimation of parameters of occurrence models has been plagued by the effect of area delineation on the parameters. Moreover, incompleteness of exploration creates a bias in parameter estimates. This study proposes that when the model is to describe the probability for occurrence of mines or prospects, the appropriate area is a metallogenic unit of mining district scale. Accordingly, this study examined the delineation of area by successive expansion of a polygon seeking that size of area which provides the best fitting of a truncated and effort-adjusted exponential model. However, estimation of occurrence model parameters was found to be sensitive to location of polygon on the cluster. Consequently, this approach was abandoned in favour of geologically-defined metallogenic units referred to as Intrinsic Samples. Truncated and effort adjusted occurrence models were fitted to Intrinsic Samples which included the mining districts of the Walker Lake Quadrangle of Nevada and California. The estimated model for each metallogenic unit is used to estimate the gold-silver metal endowment of the unit. This represents a departure from previous studies, e.g. Allais, in which a single parameter estimate from a control area is used to estimate the mineral endowment in all parts of a large study area. Furthermore, the study addresses the issue of economic truncation of occurrence data used in exponential model construction. Because a metallogenic unit is less than completely explored, estimated parameters based on observed occurrences provide a biased description of the number of occurrences present (i.e. endowment). The transition from sample to endowment (population) parameter is achieved by parameterizing the exponential model for a metallogenic unit on exploration effort deployed in a unit area. Thus, fitting the model to observed data and evaluating it at infinite effort yields the model for gold and silver metal endowment in a metallogenic unit.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineMining and Geological Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorHarris, DeVerle P.en_US
dc.contributor.committeememberNewcomb, Richard T.en_US
dc.contributor.committeememberRieber, Michaelen_US
dc.identifier.proquest9100563en_US
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