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Research about Monument Valley

Source-linked reports with geographic coverage including Monument Valley.

5 recordsLinked to original sources
USGS1958

Geology and ore deposits of the Monument Valley area, Apache and Navajo counties, Arizona: Part II

In 1951 and 1952, the U.S. Geological Survey conducted a program of uranium investigations and geologic mapping in the Monument Valley area, Apache and Navajo Counties, Ariz. About 700 square miles were mapped on the Navajo Indian Reservation. A resource appraisal of the area was an inherent part of the program, and is detailed in this report. Production of vanadium and uranium is from two areas, the Monument No. 1 mine area in Navajo County, and the Monument No. 2 mine area in Apache County. In the period 1942-53 about 200,300 tons of ore was produced from these two areas. This ore yielded about 1,700,000 pounds of U 3 O 8 and about 6,500,000 pounds of V 2 O 5 . The grade ranged from 0.15 percent U 3 O 8 to 0.60 percent U 3 O 8 , and from 0.38 percent V 2 O 5 to 3.02 percent V 2 O 5 . The vanadium-uranium ratio is about 4:1. The ore deposits are composed principally of the hydrous calcium-uranium vanadate tyuyamunite in basal channel sediments of the Shinarump member off the Chinle formation. Four types of ore bodies are present: (1) rods, (2) tabular ore bodies, (3) corvusite-type ore bodies, and (4) rolls. The reserves of uranium- and vanadium-bearing material are classed as measured, indicated, inferred, and potential. The reserves are further divided into three grade classes for material 1 foot or more thick: (1) 0.10 percent U 3 O 8 and 1.00 percent V 2 O 5 and above; (2) 0.05 percent U 3 O 8 and 0.50 percent V 2 O 5 and less than 0.10 percent U 3 O 8 and 1.00 percent V 2 O 5 ; and (3) 0.01 percent U 3 O 8 and 0.10 percent V 2 O 5 and less than 0.05 percent U 3 O 8 and 0.05 percent V 2 O 5 . Measured reserves as of June 1953, in the Monument Valley area, Arizona, (all in the Monument No. 2 mine) total about 36,000 tons. Indicated reserves in the first grade class amount to about 62,000 tons. In this same grade class inferred reserves total about 3,000,000 tons. In the second grade class indicated and inferred reserves amount to about 2,000,000 tons. Inferred reserves in the third grade class total about 345,000 tons of mineralized material. Potential reserves in all grade classes for the Monument Valley area amount to about 13,000,000 tons. It is recommended that an extensive exploration program be carried out in the Monument Valley area, Arizona. This program would consist of two phases. The first phase would involve a geophysical survey of selected channels and would have at its principal objective the delineation of the trend, length, width, and depth of scour of the channels. The second phase would consist of a diamond-drilling program that would make use of the data secured by the geophysical survey. This drilling program would have as one of its principal objectives the determination of which channels are most likely to contain ore bodies. Once the favorable channels are discovered, the drilling program could be carried on most suitably by private operators.

Arizona↗
USGS1954

Localization of uranium minerals in channel sediments at the base of the Shinarump conglomerate, Monument Valley, Arizona

During the summers of 1951 and 1952 the U.S. Geological Survey mapped the geology and uranium deposits in three 15-minute quadrangles on the Navajo Indian Reservation in Apache and Navajo Counties, northeastern Arizona. Exposed sedimentary rocks range in age from the Halgaito tongue of the Cutler formation (Permian) to the Salt Wash member of the Morrison formation (Jurassic), The dominant structural element of the area is the Monument upwarp, a arge asymmetrical anticline whose northern end is near the junction of the Green and Colorado Rivers in Utah, and whose southern end disappears near Kayenta, Ariz. Asymmetrical anticlines with steeply dipping east flanks and gently dipping west flanks are superimposed on the upwarp. These subsidiary structures trend north. The uranium ore bodies are localized in conglomeratic sandstone of the Upper Triassic Shinarump conglomerate that fills channels scoured in the underlying Lower and Middle (?) Triassic Moenkopi formation. These channels range from relatively narrow and shallow ones 15 feet wide and 10 feet deep to much broader and deeper ones 2,300 feet wide and 70 feet deep. Two types of channels can be distinguished-r-a short-type less than 2 miles Iong 5 and a long-type traceable for distances greater than 2 miles Plant matter in the form of trees, branches,'and twigs was deposited with Shinarump sediments in the channels. It is suggested that when the Shinarump conglomerate was invaded by mineralizing solutions the uranium ore was deposited primarily in localities formerly occupied by the plant material. Further, it is suggested that the short channels are more likely to have ore accumulations than long channels.

Arizona↗