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Published: 1978

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Granitic and contact-metamorphic rocks of the Owens Valley area were sampled to determine their favorability for uranium. Uranium deposits associated with these rocks were examined to determine the mode of occurrence. Metamorphic rocks near contacts with intrusive rocks include skarns, schists, quartzites, metaconglomerates, hornfels, gneisses, and metavolcanics. The grade of contact metamorphism ranges from slight to intense, depending upon the distance from the intrusive contact. The average U3O content of the metamorphic rock samples is 3 ppM. Metamorphic rock samples in a roof pendant at the Claw prospect contain as much as 3 percent U3O8. Skarn samples from the Birch Creek pluton contain as much as 114 ppM U3O8; those from the Santa Rita Flat pluton contain as much as 23 ppM U3O8. Most of the intrusive rocks are granite, quartz monzonite, or monzonite. Granodiorite and diorite are less common, and gabbro is rare. The average U3O8 content of the crystalline rock samples is 4 ppM. Samples from a quartz-monzonite pluton east of Lone Pine, California, and quartz monzonite in the Santa Rosa Hills had maximum contents of 28 and 13 ppM U3O8, respectively. Areas of contact metamorphism and metasomatism, such as those at the Claw prospect and Birch Creek pluton, are probably the most favorable sites for uranium deposits. There are many miles of granitic and contact-metamorphic zones in which undiscovered uranium deposits may exist. Although the overall uranium content of granitic rocks appears to be low, the pluton east of Lone Pine and the Hunter Mountain pluton in the area of the Santa Rosa Hills have sufficient uranium to have acted as uranium and detrital source rocks for uranium deposits that may now be buried in Tertiary sediments in the basins around the plutons. The Claw deposit is the only known uranium deposit of a size and grade to be of possible commercial interest.