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Jerry Chipman Olson

Publications and source records attributed to Jerry Chipman Olson.

16 recordsLinked to original sources
USGS1976

Uranium in the Cochetopa District, Colorado, in relation to the Oligocene erosion surface

In the Cochetopa district, Colorado, the sequence of Mesozoic and Cenozoic events is as follows: development of a relatively smooth, planar erosion surface in Jurassic time; deposition, on this surface, of the Junction Creek Sandstone and Morrison Formation of Jurassic age, followed by deposition of the Dakota Sandstone and Mancos Shale of Cretaceous age; Laramide tilting and faulting; erosion to form a terrane of moderate relief in Oligocene time; deposition of lava flows and volcanic breccia of intermediate composition and of ash-flow tuff, all of Oligocene age; and subsequent erosion and canyon-cutting by Cochetopa Creek, a superimposed stream, and its tributaries.

Open-File Report↗
USGS1957

Reconnaissance of beryl-bearing pegmatites in the Ruby Mountains, other areas in Nevada, and northwestern Mohave County, Arizona

Pegmatite occurs widely in Nevada and northwestern Arizona, but little mining has been done for such pegmatite minerals as mica, feldspar, beryl, and lepidolite. Reconnaissance for beryl-bearing pegmatite in Nevada and in part of Mohave County, Ariz., and detailed studies in the Dawley Canyon area, Elko County, Nev., have shown that beryl occurs in at least 11 districts in the region. Muscovite has been prospected or mined in the Ruby Mountains and the Virgin Mountains, Nevada, and in Mohave County, Ariz. Feldspar has been mined in the southern part of the region near Kingman, Ariz., and in Clark County, Nev. The pegmatites in the region range in age from Precambrian to late Mesozoic or Tertiary. Among the pegmatite minerals found or reported in the districts studied are beryl, chrysoberyl, scheelite, wolframite, garnet, tourmaline, fluorite, apatite, sphene, allanite, samarskite, euxenite, gadolinite, monazite, autunite, columbite-tantalite, lepidolite, molybdenite, and pyrite and other sulfide minerals. The principal beryl-bearing pegmatites examined are in the Oreana and Lakeview (Humboldt Canyon) areas, Pershing County; the Dawley Canyon area in the Ruby Mountains, Elko County, Nev.; and on the Hummingbird claims in the Virgin Mountains, Mohave County, Ariz. Beryl has also been reported in the Marietta district, Mineral County; the Sylvania district, Esmeralda County; near Crescent Peak and near Searchlight, Clark County, Nev.; and in the Painted Desert area near Hoover Dam, Mohave County, Ariz. Pegmatites are abundant in the Ruby Mountains, chiefly in the area north of the granite stock at Harrison Pass. In the Dawley Canyon area of 2.6 square miles at least 350 pegmatite dikes more than a foot thick were mapped and beryl was found in small quantities in at least 100 of these dikes. Four of these dikes exceed 20 feet in thickness, and one is 55 feet thick. A few pegmatites were also examined in the Corral Creek, Gilbert Canyon, and Hankins Canyon areas in the Ruby Mountains. The pegmatite dikes in the Dawley Canyon area intrude granite and metamorphic rocks which consist chiefly of quartzite and schist of probable Early Cambrian age. The granite is of two types: a biotite-muscovite granite that forms the main mass of the stock and muscovite granite that occurs in the metamorphic rocks near the borders of the stock. The pegmatites were emplaced chiefly along fractures in the granite and along schistosity or bedding planes in the metamorphic rocks. Many of the Dawley Canyon pegmatite dikes are zoned, having several rock units of contrasting mineralogy or grain size successively from the walls inward. Aplitic units occur either as zones or in irregular positions in the pegmatite dikes and are a distinctive feature of the Dawley Canyon pegmatites. Some of the aplitic and fine-grained pegmatite units are characterized by thin layers of garnet crystals, forming many parallel bands on outcrop surfaces. The occurrence of aplitic and pegmatitic textural varieties in the same dike presumably indicates abrupt changes in physical-chemical conditions during crystallization, such as changes in viscosity and in content of volatile constituents. Concentrations of 0.1 percent or more beryl, locally more than 1 percent, occur in certain zones or parts of zones in the Dawley Canyon pegmatites. Spectrographic analyses of 23 samples indicate that the BeO content ranges from 0.0017 to 0.003 percent in the muscovite granite, from 0.0013 to 0.039 percent in aplitic zones in pegmatite, from 0.0005 to 0.10 percent in coarse-grained pegmatite, and from less than 0.0001 to 0.0004 percent in massive quartz veins. The scheelite-beryl deposits at Oreana and in Humboldt Canyon, Pershing County., are rich in beryllium. Twelve samples from the Humboldt Canyon (Lakeview) deposit range from 0.018 to 0.11 percent BeO, but underground crosscuts have failed to intersect similar rock at depth. Beryl locally constitutes as much as 10 percent of the pegmati tic ore at Oreana. The beryl was not recovered during tungsten mining at Oreana and is now in the tailings of the mill at Toulon, Nevada, in lower percentages than the Oreana ore because of dilution by tailings from other ores milled at Toulon. Beryl has been found in numerous pegmatite dikes in the Virgin Mountains. Both beryl and chrysoberyl occur in dikes in the Hummingbird claims, north of Virgin Peak, in Mohave County, Ariz. Spectra graphic analyses of five representative samples of the principal dike on the Hummingbird claims range from 0.055 to 0.11 percent BeO.

Arizona, Nevada↗
USGS1951

Geologic map of the baritic carbonate body near Mountain Pass, San Bernardino County, California

A geologic map of an important deposit of rare earth metals studied recently by Geological Survey geologists near Mountain Pass, California has been completed Secretary of the Interior Oscar L. Chapman announced today. The discovery of this deposit was announced on January 16, and because of the great interest that has been shown in the deposit, the map is being made available for public inspection immediately, Secretary Chapman explained. The deposit covered by this map is in San Bernardino County, California near where prospectors made the original discovery on the Birthday claims in 1949. Subsequent studies by the Geological Survey have shown that an area roughly 6 miles long and 2 miles wide, extending southeast from the original discovery, contains a number of other rare carth-bearing deposits, including the large ore body covered by this map. This ore body is made up largely of a carbonate mineral and barite, but contains significant quantities of the rare earth mineral, bastnasite as well. It is exposed over an area 2,400 feet long and 400 feet wide.

California↗