Uranium Hydrogeochemical and Stream Sediment Reconnaissance of the Pueblo NTMS Quadrangle, Colorado

摘要

A total of 861 water and 1060 sediment samples were collected from 1402 locations. Samples were collected at a nominal density of one sample location per 10 km exp 2 over a 19,700-km exp 2 area. Water samples were collected from streams, wells, springs, artificial ponds, and natural ponds; sediment samples were collected from streams, springs, artificial ponds, and natural ponds. Evaluation of the data resulted in the delineation of areas in which water and/or sediment uranium contents are notably higher than the surrounding background values. For water samples, which have a mean uranium concentration of 5.88 ppB, an arbitrary anomaly threshold of 36 ppB was chosen. The major clusters of anomalous water samples are from locations in Quaternary sediments, the Pierre shale, and the Niobrara formation in the Arkansas River valley and in faulted Precambrian granodiorite along Fernleaf Gulch near Cotopaxi. Many anomalous water samples are from locations along northwesterly-trending fault zones. For sediment samples, the mean content is 7.08 ppM and the arbitrary anomaly threshold is 25 ppM uranium. Most anomalous sediment samples were collected in areas of the Front Range underlain by Precambrian igneous rocks, specifically the Pikes Peak granite, the Cripple Creek quartz monzonite, and the Boulder Creek granodiorite. Most anomalous water and sediment samples from mountain locations are associated with fault zones and reported uranium occurrences. (10 figs., 5 tables). (ERA citation 04:018052)