English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Closely spaced measured stratiqraphic sections of the lower part of the Late Triassic Chinle Formation in the White Canyon area of southeastern Utah depict a fluvial-deltaic-lacustrine depositional sequence that hosts uranium deposits in basal fluvial sandstones. The basal Shinarump Member consists of predominantly trough-crossbedded, coarse-grained sandstone and minor gray, carbonaceous mudstone and is interpreted as a valley-fill sequence overlain by deposits of a braided stream system. The overlying Monitor Butte Member is composed of cyclicand foreset-bedded siltstone, sandstone, and nudstone and is interpreted as a succession of low-energy fluvial, deltaic and organicrich, lacustrine-marsh sediments. The overlying Moss Back Member is composed of a laterally extensive, coarseto medium-grained, conglomeratic sandstone and is interpreted as a braided-stream system that flowed north to northwest. The entire sequence was deposited in response to changes in local base level associated with a large lake that lay to the west. Isopachs of lithofacies indicate distinct lacustrine basins and a correspondence between these facies and modern structural synclines. Facies changes and coincidence of isopach thicks suggest that structural synclines were active in the Late Triassic and influenced the pattern of sediment distribution within the basins. Uranium mineralization appears to be related to certain low-energy depositional environments in that uranium is localized in fluvial sandstones that lie beneath organic-rich lacustrine-marsh mudstones and carbonaceous delta-front sediments. The reducing environment preserved in these facies may have played an important role in the localization of uranium. INTRODUCTION AND PREVIOUS WORK The Chinle Formation in the White Canyon area has been studied extensively, in part due to the economic importance of uranium located in basal fluvial sandstones. Stewart and others (1959, 1972a, 1972b) made regional stratigraphic correlations of the Chinle and related formations, which include the White Canyon and adjacent areas. The geology and ore deposits of the White Canyon (Thaden and others, 1964), Elk Ridge (Lewis and Campbell, 1956), Deer Flat (Finnell and others, 1963), and Monument Valley areas (Witkind and Thaden, 1963) have been investigated in some detail; each report describes local stratigraphy and ore controls. Regional studies of uranium deposits (Finch, 1959; Johnson and Thordarson, 1966) were concerned with large-scale trends, controls, and distribution of uranium ore. The present study investigates in detail the stratigraphy, sedimentology, facies relationships and depositional enviroments, and their possible relationship to uranium occurrences in portions of the White Canyon, Henry Mountains, and Green River uranium districts (fig. 1) (Johnson, 1959; Johnson and Thordarson, 1966). Measured sections were chosen for completeness of section and exposure; included were areas of uranium occurrences, prospects, and mines, and areas that contain no known uranium occurrences. Fifty-five stratigraphic sections of the Shinarump, Monitor Butte, and Moss Back Members of the Upper Triassic Chinle Formation were measured at approximately 5 mi (8 km) intervals in and adjacent to the White Canyon uranium district (Johnson and Thordarson, 1966) of southeastern Utah (fig. 1). The sedimentology and facies relationships of this series of continental

Sedimentology of the lower part of the upper Triassic Chinle Formation and its relationship to uranium deposits, White Canyon area, southeastern Utah