Reconnaissance geology and resources of Miocene diatomite, Trinity Pass area, Pershing County, Nevada

Abstract

Deposits of Miocene diatomite in the Trinity Range, west of Lovelock, have supported significant mining for more than 30 years. Gently dipping sequences of diatomite and tuff, comprising more than 100 m of high quality diatomite, are mass mined in four open-pit mines. The high quality diatomite is processed at Colado for filter aids and fillers. The diatomite formed at about 15 Ma in a freshwater lake created during the early stages of Basin-and-Range faulting and volcanism. The deposits were preserved by unusually gentle Tertiary tectonics. Technical properties of the diatomite were protected from destructive diagenesis by uplift shortly after deposition, and protected from erosion by cover afforded by rhyolite, basalt, and gravel. Geologic relations support a likely large inferred resource of diatomite, under less than 30 m of cover, that is favorable for future mining.

Resource assessment of the Bureau of Land Management's Winnemucca District and Surprise Resource Area, Northwest Nevada and Northeast California; geology and its relation to resource genesis

“…Several types of non-metallic mineral resources developed in association with rocks of the bimodal basalt-rhyolite assemblage. These include diatomite deposits in lacustrine sedimentary rock sequences (Nash, 1995), perlite in hydrated obsidian units, sulfur at hydrothermal hot-spring deposits (for example, Sulphur Mining District), precious opal in hydrothermally altered sedimentary and volcanic rocks (for example, Virgin Valley) and pumice associated with young volcanic units.…”

Resource assessment of the U.S. Bureau of Land Management's Winnemucca District and Surprise Resource Area, northwest Nevada and northeast California; resources of industrial rocks and minerals

“…Assessment: Permissive tracts are associated with Miocene normal fault zones and volcaniclastic-sedimentary rocks. Large proven and inferred resources remain for mining in the Trinity Range (Nash, 1995), and exposed diatomite north of Bradys Hot Spring is highly prospective. Many diatomite occurrences in the western part of the WSRA appear to be too thin to be viable.…”

“…References: Kady, 1983a;Shenk, 1991;Lenz and Morris, 1993;Nash, 1995 Geologic setting: This is a very rare deposit type and is no longer of high development interest; no other dumortierite deposits in the world have been developed. Dumortierite forms by contact metamorphism of strata having unusually high aluminum content.…”