No abstract

This report is a summary of U. S. Geological Survey investigations of the geological effects of the Rainier underground nuclear explosion which was detonated at the Atomic Energy Commission's Nevada Test Site on September 19, 1957. The 1.7 kiloton explosion took place 900 feet below the surface of the ground at the end of a tunnel driven into volcanic tuff of the Oak Spring formation. The rocks close to the explosion point were white to brown pumiceous rhyolitic tuffs that contain phenocrysts of quartz and feldspar biotite and xenoliths of older rocks embedded in a fine-grained matrix of heulandite, clay, ,^-cristobalite, and amorphous material. Unconnected open vesicles make up to 11.5 percent by volume of the rocks. In the natural state these rocks have an average porosity of 24 percent, a bulk density of 2.0, a water content of 14 percent by weight, an acoustic velocity of 8,300 feet per second, a coppressive strength of roughly 4,000 psi at atmospheric pressure, and a tensile strength of roughly 100 psi. Under confining pressures greater than 10,000 psi the tuff will deform at least 20 percent with a consequent increase in density of about 8 percent.Exploration of the rocks disturbed by the explosion has been carried out by one vertical hole and 3 near-horizontal holes and by tunneling toward the point of the explosion. This exploration has revealed a breccia zone extending 70 feet from the explosion chamber. The breccia contains radioactive glass, angular to subrounded blocks, 0.3 to 3 feet across in a

20 Analyses of samples from the Robinson property, San Miguel County, Colorado. • .. o • • • 0 0 0 0 0 0 o 0 o o • o o o o o 30 Detatled stratigz;aphic section of the Dolores formation a~ the Weatherly property , San Miguel County, Colorado • 0 0 0 40 Analyses of samples from the Weatherly property, San Miguel County, Colorado o • o o o o 0 •. • • o 0 0 • o o • o o o ., o • 50 Semi-quantitative spectrographic analyses of sele. cted pyrobitumen specimens, Weathedy property, San Miguel County, Colorado

The papers comprising the various parts of this report contain preliminary results of the U. S. Geological Survey investigations in the Ul2b.03 and Ul2b.04 tunnels at the Nevada Test Site, Nye County, Nevada (fig. 1). The geologic studies were undertaken to define the structural, chemical, mineralogic, and some of the physical properties of the tuffaceous rocks that enclose the explosion chambers at the end of each tunnel. The U12b.03 and .04 tunnels are part of the Ul2b (Rainier) tunnel complex that was driven northwestward from the steep east slope of Rainier Mesa (a prominent topographic feature in the northwest part of the Test Site (fig. 2)).The U12b.03 tunnel trends north from a point about 980 feet from the portal of the Ul2b tunnel (fig. 3).The Ul2b.03 tunnel consists of 620 feet of tunnel, two alcoves, and a shot chamber. The tunnel is irregular, ranging from 6 to 10 feet in width, and 6 to 9 feet in height.The shot chamber at the north end of the tunnel is 22 feet on each side. The vertical and minimum cover over the shot chamber are 610 and 510 feet, respectively.

Reviewen Otu. Date Trace Elements Investigations Report 158 This preliminary report is distributed without editorial and technical review for conformity with official standards and nomenclature. It is not for public inspection or quotation.

This report concerns work done on behalf of the U. 8. Atomic Energy Commission and is published with the permission of the Commission.

An area about 6 miles north of Sundance, in the Bear Lodge Mountains, in Crook County, Wyo., was examined during August 1950 for thorium, uranium, and rare-earth oxides an& samples were collected.

Introduction ______________________________________ _ Selection of deposits for study ___________________ _ Field and laboratory work ______________________ _ Acknowledgments ______________________________ _ Uses and production of beryllium ____________________ _ Exploration program _______________________________ _ Methods and costs _____________________________ _ ResuUs _______________________________________ _ Methods of estimating beryl content _________________ _ Tonnage of beryl-bearing units __________________ _ Grade ________________________________________ _ Sampling _________________________________ _ Spectrographic analyses ____________________ _ Grain measurements _______________________ _ Determinations of index of refraction _________ _ Comparison of methods used in determining grade ___________________________________ _ Helen Beryl pegmatite _____________________________ _ Mine workings ________________________________ _ Production ____________________________________ _ Geology ______________________________________ _ Metamorphic rocks ________________________ _ Quartz and quartz-feldspar veins ____________ _ Pegmatite ________________________________ _ Albite-quartz-muscovite pegmatite (wall zone) _______________________________ _ Granitic albite-quartz-muscovite pegmatite_ Gneissoid albite-biotite-quartz pegmatite __ _ Perthite-quartz-albite pegmatite (fracturefilling units in wall zone) ______________ _ Perthite-quartz-muscovite-biotite pegmatite (first intermediate zone) ______________ _ Perthite-quartz-muscovite pegmatite (second intermediate zone) _______________ _ Perthite-spodumene-quartz pegmatite (third intermediate zone) ___________________ _ Quartz-spodumene-perthite-albite pegmatite (core) ___________________________ _ Diamond-drilling ______________________________ _ Mineral deposits _______________________________ _