Mineral resources of the Gros Ventre Wilderness Study Area, Teton and Sublette counties, Wyoming

Abstract

The Gros Ventre Wilderness Study Area, located in the Bridger-Teton National Forest, is about mi (600 km) in extent and is directly east of the town of Jackson in west-central Wyoming. It comprises a large part of the Gros Ventre Range, which rises between the Gros Ventre River to the northeast and the Hoback River to the southwest, both tributaries of the Snake River. Rocks of the area comprise granite, granitic gneiss, and some amphibolite of Precambrian age; a section of Paleozoic sedimentary rocks mostly limestone, sandstone, shale, and dolomite about 3,500-4,000 ft (1,065-1,200 m) thick which has representatives of all periods except the Silurian; a section of Mesozoic sedimentary rocks, almost entirely sandstone and shale, totaling about 13,000-15,000 ft (4,000-4,575 m) in thickness; and a section of Cenozoic (Tertiary) sedimentary rocks that is probably as much as 13,000 ft (3,960 m) thick. Bedrock is concealed by unconsolidated deposits of Quaternary age over about 10-15 percent of the area. Structurally, the Gros Ventre Range is a northwest-trending, broad anticlinal arch with a gently dipping northeast limb, interrupted by several folds asymmetrical to the southwest and by one fault of substantial displacement, and a steeply dipping, thrust-faulted, and structurally complex southwest limb. The central part of the range consists mostly of Paleozoic rocks; Precambrian rocks are restricted to the southwest part, and Mesozoic and consolidated Cenozoic rocks occur for the most part only well down the flanks. Rocks at the southwest crest of the Gros Ventre are now 30,000-35,000 ft (9,150-10,675 m) above corresponding rocks in the adjoining Hoback Basin to the southwest; this uplift took place along the northeast-dipping Cache Creek thrust fault and related faults in early Tertiary time. No exploratory drilling for oil or gas has been done within the study area. A well drilled recently on Granite Creek about 5 mi (8 km) southwest of the study area has numerous shows of gas. Several other wells, all dry holes, have been drilled within a few miles southwest, south, and southeast of the area. No hot springs are known in the study area, although a few small hot springs occur just south of the area along Granite Creek. The lack of heat sources indicates that the geothermal energy potential is low. Large quantities of high-quality limestone and dolomite exist in the study area, but they are not considered as valuable mineral resources because such rock is readily available nearer to markets in other parts of Wyoming. INTRODUCTION The Gros Ventre Wilderness Study Area, in the Gros Ventre Range of northwestern Wyoming, is about 23 mi (37 km) long in an easterly direction by 21 mi (33.5 km) wide and consists of about 230 mi (600 km) within the Bridger-Teton National Forest (fig. 2). Most of the area is in Teton County but about 35 mi (90 km) is in the southeastern part is in Sublette County. The study area is drained mostly by the Gros Ventre River and Flat, Horse, Granite, and Dell Creeks and their tributaries. Altitu...

Crustal Structure Interpreted From Magnetic Anomalies

“…Campbell [1987] provided a map and interpreted profiles for a large area of south‐central Alaska. Many new aeromagnetic maps of smaller areas also appeared [Antweiler et al, 1989; Blank and Kucks, 1989; Bond, 1987; Bracken and Godson, 1987, 1988; Bracken et al, 1989a, b; Case and Nelson, 1987; Case et 1988, in press; Davis, 1989; Drewes et al, 1988; du Bray et al, 1987; Flanigan et al, 1987; Grauch, 1987b, 1988a, b; Grauch and Plesha, 1989; Greenwood et al, 1990; Hildenbrand et al, 1988; Keith et al, 1988; King, 1987; Kirchoff‐Stein et al, 1989; Klein, 1987; Kleinkopf et al, 1988, 1989; Mariano and Grauch, 1988; Martin, 1987a, b; McCafferty et al, 1989; Moore et al, 1988; Plouff, 1987; Ponce and Langenheim, 1987; Saltus and Ponce, 1988; Simons et al, 1988; Simpson et al, 1989; USGS, 1987a,b,c,d,e,f,g,h,i,j,k, 1988a,b,c, 1989b; Van Loenen et al, 1989].…”