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GEOREF RECORD

Paragenesis and structure of pitchblende-bearing veins, Central City District, Gilpin County, Colorado

Paul Kibler Sims
Paragenesis and structure of pitchblende-bearing veins, Central City District, Gilpin County, Colorado
Economic Geology and the Bulletin of the Society of Economic Geologists (December 1956) 51 (8): 739-756

Abstract

Pitchblende occurs locally along early Tertiary gold-, silver-, and sulfide-bearing quartz veins in the Central City district, Colorado, within the mineral belt of the Front Range. The veins cut a complex mass of Precambrian metamorphic and igneous rocks and early Tertiary intrusive porphyritic rocks.The veins are fissure fillings that formed at intermediate temperatures and pressures. They consist mainly of pyrite, sphalerite, and galena in a quartz gangue, but also contain tennantite, chalcopyrite, enargite, and pitchblende. The veins differ in quantitative mineralogy, and they can be classified as pyrite-type and galena-sphalerite-type veins. Vein filling took place during three stages of mineralization, from oldest to youngest: a uranium stage, a pyrite stage, and a base-metal stage. Major periods of fracturing and vein reopening took place between the vein-forming stages.The pyrite and base-metal stages of mineralization were of broad areal extent and produced a concentric zonal arrangement of the ores in the district. In contrast, the uranium stage of mineralization was local in extent and resulted in scattered clusters of uranium deposits, which show no definite spatial relation to the district-wide zoning pattern.Pitchblende is present in only a few veins. The ore bodies are localized in structurally controlled open spaces along faults. They occur locally along four of the six vein sets of the district, in the form of ore shoots or small lenses and pods that are separated by vein material essentially devoid of uranium. The shoots are small and measure at most a few tens of feet in height and length, and average less than a foot in width; few contain more than 50 tons of ore. Some of the shoots are systematically arranged within the veins but others are erratically distributed.


ISSN: 0361-0128
EISSN: 1554-0774
Coden: ECGLAL
Serial Title: Economic Geology and the Bulletin of the Society of Economic Geologists
Serial Volume: 51
Serial Issue: 8
Title: Paragenesis and structure of pitchblende-bearing veins, Central City District, Gilpin County, Colorado
Author(s): Sims, Paul Kibler
Pages: 739-756
Published: 195612
Text Language: English
Publisher: Economic Geology Publishing Company, Lancaster, PA, United States
Accession Number: 1959-028347
Categories: Economic geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N39°45'00" - N39°49'60", W105°34'60" - W105°19'60"
Source Note: discussion by J. S. Vanderpool, p. 713, Sept.-Oct. 1957.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Society of Economic Geologists. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Update Code: 1959
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