Abstract. Neogene extension in the Death

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Carnotite was discovered in June 1~51 in the Crav.en Canyon area, sees. 24 and 25, T. 7 S~~B. 2 E. and what wouid be sees. 19 and 30 of unsectioned T. 7 S.~ R. 3 E. 9 Fall River County 9 S.--Dak. Although little prospecting had been carried out before November 18~ 1951, more than 28 claims had been staked by that date.The known carnotite occurrences are restricted to the b~sal 100 to 150 feet of the Lower Cretaceous Lakota sandstone; most are within 50 feet of a distinctive, paper-weathering, nonradioactive~ carbonaceous, 1-to 3-foot black shale that is 100 to 125 feet above the top.of the underlying Morrison formation. Three favorable zones have been recog- nized~(1) a zone 20 to 30 feet above the carbonaceous shale horizon, (2) a zone 20 to 30 feet below the carbonaceous shale horizon~ and (3) a zone about 25 feet below (2). Possibly a fourth zone may occur 20 feet below (3).The deposits generally ar~ parallel to bedding 9 but in detail are cross-cutting. Widespread carnotite stains.coat fractures in and adjacent to the deposits. These stains are commonly' associated with an un= identified, green mineral stain that contains uranium and vanadium.The only exploitable ore bodies discovered by November 1951 are of small size, but the presence of many widespread and lo~grade deposits suggests that additional commercial deposits may be found by further prospecting.

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