Geologic setting and trace metal chemistry of the Arapien Shale and Twist Gulch Formation, Central Utah
Loading...
Date
1979
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
The Ohio State University
Abstract
The Arapien Shale and Twist Gulch Formation of Jurassic age were studied as possible future sources of economic concentrations of base- and precious-metals. Copper, lead, zinc, and silver contents were determined by atomic absorption spectrophotometry. Lead and zinc are slightly enriched when compared to other shales and mean crustal abundances, whereas copper concentrations were slightly lower. Silver was not detected in any of the samples. Two types of metal enrichment were found: 1) a syngenetic (sabkha-type) copper enrichment expressed as interstitially deposited metal sulfides, and; 2) an epigenetic enrichment as veinlets and disseminations of chalcocite, malachite, and azurite. The latter mineralization perhaps is related to normal faulting in the area studied, The importance of the Arapien Shale and Twist Gulch Formation as a future source of metals may lie with the syngenetically enriched segments associated with evaporite beds. This association may represent a Jurassic sabkha environment. The association encountered in the present study does not contain economic concentrations of copper. However, it may indicate that larger associations may be present in these formations.