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W.I. Finch

Publications and source records attributed to W.I. Finch.

13 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↗
USGS1993

The deposit size frequency method for estimating undiscovered uranium deposits

The deposit size frequency (DSF) method has been developed as a generalization of the method that was used in the National Uranium Resource Evaluation (NURE) program to estimate the uranium endowment of the United States. The DSF method overcomes difficulties encountered during the NURE program when geologists were asked to provide subjective estimates of (1) the endowed fraction of an area judged favorable (factor F) for the occurrence of undiscovered uranium deposits and (2) the tons of endowed rock per unit area (factor T) within the endowed fraction of the favorable area. Because the magnitudes of factors F and T were unfamiliar to nearly all of the geologists, most geologists responded by estimating the number of undiscovered deposits likely to occur within the favorable area and the average size of these deposits. The DSF method combines factors F and T into a single factor (F??T) that represents the tons of endowed rock per unit area of the undiscovered deposits within the favorable area. Factor F??T, provided by the geologist, is the estimated number of undiscovered deposits per unit area in each of a number of specified deposit-size classes. The number of deposit-size classes and the size interval of each class are based on the data collected from the deposits in known (control) areas. The DSF method affords greater latitude in making subjective estimates than the NURE method and emphasizes more of the everyday experience of exploration geologists. Using the DSF method, new assessments have been made for the "young, organic-rich" surficial uranium deposits in Washington and idaho and for the solution-collapse breccia pipe uranium deposits in the Grand Canyon region in Arizona and adjacent Utah. ?? 1993 Oxford University Press.

Nonrenewable Resources↗
USGS1980

Research on interactive genetic-geological models to evaluate favourability for undiscovered uranium resources

Current methods of evaluating favourability for undiscovered uranium resources are unduly subjective, quite possibly inconsistent and, as a consequence, of questionable reliability. This research is aimed at reducing the subjectivity and increasing the reliability by designing an improved method that depends largely on geological data and their statistical frequency of occurrence. This progress report outlines a genetic approach to modelling the geological factors that controlled uranium mineralization in order to evaluate the favourability for the occurrence of undiscovered uranium deposits of the type modeled. A genetic model is constructed from all the factors that describe the processes, in chronological sequence, that formed uranium deposits thought to have a common origin. The field and laboratory evidence for the processes constitute a geologic occurrence base that parallels the chronological sequence of events. The genetic model and the geologic-occurrence base are portrayed as two columns of an interactive matrix called the "genetic-geologic model". For each column, eight chronological stages are used to describe the overall formation of the uranium deposits. These stages consist of (1) precursor processes; (2) host-rock formation; (3) preparation of host-rock; (4) uranium-source development; (5) transport of uranium; (6) primary uranium deposition; (7) post-deposition modification; and (8) preservation. To apply the genetic-geological model to evaluate favourability, a question is posed that determines the presence or absence of each attribute listed under the geologic-occurrence base. By building a logic circuit of the attributes according to either their essential or non-essential nature, the resultant match between a well-documented control area and the test area may be determined. The degree of match is a measure of favourability for uranium occurrence as hypothesized in the genetic model. This process of geological decision analysis results in a series of favourability maps that can be combined into a final composite favourability map.

Conference Paper↗
USGS1976

Uranium resource assessment in the United States

Uranium is a ubiquitous element-- a little is found in nearly every natural occurring materials, and it is concentrated in many different geologic environments. Thus, uranium differs markedly from the fossil fuels both in its occurrence and how its resources can be assessed. On the one hand uranium behaves like other metals in its occurrences. On the other hand, as a fuel it is like the hydrocarbons in that it is a non-recyclable resources. In addition, uranium occurs in two isotopes that potential may supply energy-- U235 and U238. Present only 0.7% of natural uranium. New technology is being developed to utilize the more abundant isotope U238. Consequently, the U238 obtained from uranium ores that have already been mined and processed (which is now stockpiled) is a resource that may be used in the future.

Conference Paper↗
USGS1960

Chemical composition as a guide to the size of sandstone-type uranium deposits in the Morrison Formation on the Colorado Plateau

The concentrations of uranium, yttrium, sodium, iron, zirconium, manganese, calcium, and nickel in 75 mill-pulp samples of uranium deposits in the Salt Wash member of the Morrison formation on the Colorado Plateau have been found, by statistical tests, to be significantly related to the size of the deposits represented by the samples. The elements mentioned above are related to the formation of the deposits in a variety of ways. Zirconium is an intrinsic element, contained principally in the detrital syngenetic fraction of the host sandstone. Calcium, manganese, and sodium are intrinsic elements contained principally in epigenetic (diagenetic) carbonate in the host sandstone. Uranium, yttrium, and nickel are principally extrinsic elements, introduced into the host sandstone by uranium mineralization or related processes. Somewhat more than half of the iron is probably intrinsic and the remainder is extrinsic. Three methods can be used to estimate the size of uranium deposits in the Salt Wash, member within broad limits. Method 1 is based on simple linear-regression theory; method 2 is based on multiple-regression theory (long method); and method 3, on multiple-regression theory (short method). For methods 1 and 2 the estimated log size of each deposit can be computed from tables showing the known concentration of uranium, yttrium, sodium, iron, zirconium, manganese, calcium, and nickel in the deposits, as determined by semiquantitative spectrographic analysis. For method 3 the estimated size or log size can be read directly from a table showing known concentration of uranium and yttrium only. About 80 percent of the tonnage-size estimates from method 1 will be within a factor of 13 (12-14) of the true sizes. The precision of the size estimates from method 2, the long multiple-regression method, is highly variable. Some estimates from method 2 will be within a factor of 12 of the true size at the 80-percent confidence level; others, within a factor of 40 at the 80-percent confidence level. About 80 percent of the tonnage-size estimates from method 3, the short multiple-regression method, will be within a factor of 15 (13-16) of the true size. A group of 40 deposits of known size was used to test the theoretical derivation of the confidence intervals given above. It was concluded from the test that the confidence intervals describe the precision of the methods correctly. The methods for estimating the size of uranium deposits are useful where the ore is poorly exposed or where an independent estimate is desired. The error of the estimates may be quite large, as indicated by the confidence limits given above; but the estimates can be used to, at least, distinguish very large from very small deposits. They also may serve to encourage or discourage further expenditures in the development and exploration of ore bodies. The methods of size estimation can be particularly useful in attempts to appraise or compare groups of deposits or mining districts, inasmuch as the average estimate of size of deposits in a group is more precise than any single estimate. The methods for estimating size are established only for deposits in the Salt Wash member of the Morrison formation. Tests indicate that the equations calculated for deposits in the Salt Wash fail completely if applied to deposits in other stratigraphic units, such as the Moss Back and Shinarump members of the Chinle formation. A further restriction, not completely evaluated at present, is that semiquantitative spectrographic analyses of mill-pulp samples are required. No tests have been made to determine the precision and accuracy of the methods when other types of samples, such as drill core, are used.

Arizona, Colorado, New Mexico, Utah↗
USGS1959

Peneconcordant uranium deposit: A proposed term

The term peneconcordant is proposed to describe the form of the numerous and highly productive U deposits in sedimentary rocks of the Colorado Plateau, Wyoming, the Dakotas, and Texas. Peneconcordant U deposits are tabular, lenticular, or irregularly-shaped masses of widely differing size that are, in general, concordant to the gross sedimentary structures of the enclosing rock but that in detail cut across sedimentary structures. They differ from vein deposits in that they do not occupy or follow fractures or shear zones in the sedimentary rocks. Furthermore, they are not coextensive with a specific lithologic unit, such as U-bearing marine black shale. The many terms now used to describe these U deposits are based variously on petrographic, mineralogic, geographic, and genetic considerations; none is satisfactory for describing all these deposits having a common and distinctive form. Furthermore, some of the terms are ambiguous and have been commonly used to group together deposits having distinctly different forms. The term peneconcordant U deposit clearly sets apart a widespread and important type of U deposit that has a common and distinctive form, namely, nearly concordant to the bedding of the host rock. The meaning of the term is self-evident, and the term is readily applicable to field usage.

Economic Geology↗