Progress report on investigations of western phosphate deposits

Abstract

Trace Elements UNITED STATES

Mineral resources in Permian rocks of southwest Montana

“…The interval o:f Permian rocks above the Retort l\1ember -formerly referred to as the E member by Swanson, McKelvey, and Sheldon (1953)-is a little more than 100 feet thick in the Melrose district and is dominated by quartzitic sandstone (the upper member of the Shedhorn Sandstone). Chert of the Tosi Member of the Phosphoria is common but thin at the base of the sandstone.…”

“…The Permian phosphate deposits in Montana have been investigated intermittently by the U.S. Geological Survey since 1910, when phosphate was first discovered near Melrose by Gale (1911). Since World War II, all the potential phosphate area of ~fontana has been studied as part of a larger investigation of the entire western phosphate field (Mcl(elvey, 1949;Swanson, McKelvey, and Sheldon, 1953). This report describes the mineral resources in the Permian rocks in southwest ~fontana and adjacent parts of Idaho and "\Vyoming ( fig.…”

“…He correlated the rock types and rock sequences with the transgressions and regressions of the sea and with the probable pH (above .or below 7.8) and Eh ( abov'e or below zero) of the environment of sedimentation. Based on pririci pies first defined by l(azakov (1937) and later'applied with modifications by l\icl(elvey (1\icl\:elvey, Swanson, and Sheldon, 1953) to the Phosphoria, Sheldon (1957) showed that these controls were operative in an area near the outer edge of the platform where phosphate, carbonate, and silica in solution were supplied by cold marine currents, rising from the geosyncline to the west, while clastic sediments were supplied from low-lying areas on the north and the northeast. Extending this concept further, Sheldon (1959) analyzed the distribution of uranium in the phosphatic shales of the Phosphoria Formation and showed for northwestern Wyoming that the phosphatic sediments deposited in an environment of low Eh are richer in uranium and that the pH of the environment could not be sh0wn to affect.…”

Geology of the Johnson Creek quadrangle, Caribou County, Idaho

“…The phosphate deposits of this quadrangle are among the thickest and richest of the entire western phosphate field (Swanson, McKelvey, and Sheldon, 1953), but the largest part of the deposits is deeply buried. The phosphate rock occurs as beds at different horizons in the Phosphoria formation and is composed of carbonate-fliiorapatite and varying proportions of quartz, dolomite, calcite, and carbonaceous material.…”

Geology and phosphate deposits of the Permian rocks in central western Montana

“…After World War II, extensive investigations were carried out in the entire western phosphate field. Preliminary reports of this work were made by McKelvey (1949) and Swanson, McKelvey, and Sheldon (1953). Cressman and Swanson (1964) reported on the stratigraphy and petrology of the Permian rocks in the area south of Butte, and Swanson (19TO) reported on the mineral resources in those rocks.…”