Gamma-Ray Spectrometry in Geologic Mapping and Uranium Exploration
Gamma-ray spectrometry, airborne or ground, may be useful in a wide variety of geologic mapping applications because the concentrations of uranium, thorium, and/or potassium may be diagnostic of rock type in many uranium, base, and precious metal environments. However, in areas of little outcrop, the surface material must be either residual or locally derived before gamma-ray spectrometry can be applied successfully. In its alternate application—direct detection of uranium—gamma-ray spectrometry has been remarkably successful in recent years. However, for direct detection of uranium deposits, gamma-ray spectrometry will decrease in its application because most deposits occurring sufficiently close to surface to be detected have already been found.
To be of maximum use to the explorationist, data from gamma-ray spectrometry surveys must be acquired with utmost care. Accordingly, attention must be directed to the evaluation of such problems as disequilibrium in the uranium decay series, removal of atmospheric background radiation, the effect of rainfall and other meteorological phenomena, calibration of spectrometers, statistical errors in count rates, fields of view of gamma-ray detectors, and the effect of overburden. Modern instrumentation, calibration, and analysis are such that data can be evaluated with such care that as little as 1 ppm U, 1 ppm Th, or 0.1 percent K can be detected reliably with an airborne or ground gamma-ray spectrometry survey.
Figures & Tables
Seventy-Fifth Anniversary Volume
The first notions of a new journal came to J. E. Spurr during the closing days of 1904. When he shared his thoughts with friends in Washington, D. C., they were so enthusiastic about the suggestion that they formed themselves into an ad-hoc committee to seek ways to implement the idea. The ad-hoc group met informally for several months and by May of the following year was ready to announce the birth of an unusual new publishing company and the journal the company would produce. The first formal meeting of the Economic Geology Publishing Company took place on May 16, 1905. The first issue of the new journal appeared in October of the same year, and the first volume was completed in December 1906. The birthing was not easy, but it was successful because the founders provided much of the financing as well as the first papers. The story of those earliest days and the many struggles of the fledgling journal is engagingly recounted by Alan M. Bateman in an article published in the Fiftieth Anniversary volume.
From inception, management of the journal has differed from the management of most scientific journals. There was no sponsoring society, so the founders raised capital by incorporating and selling shares in the venture. The journal has been owned and published by the Economic Geology Publishing Company ever since. There is no record that the founders experienced difficulties in selling shares in the Company, but they must have had some because the Publishing Company had a goal that other corporations(and presumably many of the investors) would have found difficulty in understanding: the new corporation was committed to keeping the books balanced but not to making a profit.
Initially incorporated in the District of Columbia, the Publishing Company was reincorporated in 1970 as a nonprofit membership corporation in Delaware. The modification in corporate status came in response to a suggestion made by the Internal Revenue Service.
The affairs of the Publishing Company are controlled by a Board of Directors, and the journal is sold to the public by direct subscription. Day-to-day operations of paper selection, review, and printing are in the hands of the Editor, while business matters, such as subscriptions and advertising, are in the hands of the Business Editor.
The one tie the Publishing Company has with a society was instituted many years after the journal. was founded—with the Society of Economic Geologists. When the Society was founded in 1920 it first considered publishing its own bulletin. Because the venture seemed financially questionable, and the coffers of the new society were bare, an arrangement was reached whereby members of the Society first received offPrints of papers written by its members and eventually Economic Geology as