Report presenting the results of a survey in the southwest segment of the Zuni Uplift sedimentary formations. The report includes figures and plates that provide an overview of physical geography in the area, as well as economic geography, including mineral deposits.

Results of a survey in the southwest segment of the Zuni Uplift sedimentary formations. It includes an overview of physical geography in the area, as well as economic geography, including mineral deposits.

Although uranium gas first discovered in the Carrizo Mountains area in 1918, the ores were not developed until 1942. They have, however, been mined continuously since that time. Formations in the area range from the Pernian Cutler through the Cretaceous Mancos shale, and all are intruded by a dioritic laccolith and its related dikes. The older structures, which include the Defiance Uplift, the San Juan Basin, and the Four Corners Platform are somewhat disrupted by the effects of the intrusion. A number of mines are described and mineralogical and geochemical studies made are outlined. The primary uranium mineral is unknown, but the chief uranium ore-mineral is the secondary mineral, tyuyamunite. It is concluded that there is at least minor structural control of the ore bodies along sedimentary trends and joints, and that all ore bodies of 500 tons or more are on the Defiance monocline or its extensions. The uranium may have been syngenetic in the sediments, and redistributed by solutions or, more likely, that it rose vertically in hydrothermal solutions from the local intrusive bodies.

From Purpose, Scope, and Methods: The objective of this study was an evaluation of resources of the Carrizo Mountains area. Four factors: distribution of ore bodies, relation of uranium to the host rock, relation of ore to structure, and circumstances that might precipitate uranium were studied in search of data bearing on manner of distribution of ore, the time and causes of deposition, and the probable source of the uranium-bearing solutions.

From introduction: This is one of a series of three reports on airborne radioactivity surveys in the United States. The reports contain the 185 airborne anomaly maps issued by the U. S. Atomic Energy Commission as a result of the AEC's aerial surveying program conducted from March 1952 to June 1956; two ground reconnaissance maps of Utah also are included. Most of the reconnaissance was done in the western United States.