GEOLOGY OF THE GREEN RIVER MINING DISTRICT, EMERY AND GRAND COUNTIES, UTAH

摘要

Uranium deposits have been known since the 1880' s in the Green River district of eastern Emery County and western Grand County in southeastern Utah. Outcropping rocks include the Entrada sandstone and the Carmel, Curtis, Summerville, and Morrison formations of Late Jurassic age;the Cedar Mountain formation of Early Cretaceous age, the Naturita formation of probable Late Cretaceous age in this area, and the Mancos shale of Late Cretaceous age. Uranium is found chiefly in the Salt Wash sandstone member of the Morrison, and the largest deposits occur in a thick sandstone unit near the top of the member in the Tidwell mineral belt near the western edge of the district.nThe basic structure of the district is that of a broad northward-plunging syncline which projects thumblike from the southern margin of the Uinta Basin, bounded on the east by the Green River nose of the Cane Creek anticline, on the south by the Nequoia arch, and on the west by the San Rafael Swell.