Publications

A borehole sonde (~1.7 m long; 7.3 cm diameter) using a 200 mm2 planar intrinsic germanium detector, mounted in a cryostat cooled by removable canisters of frozen propane, has been constructed and tested. The sonde is especially useful in measuring X- and low-energy gamma-ray spectra (40–400 keV). Laboratory tests in an artificial borehole facility indicate its potential for in-situ...

No abstract available.

No abstract available.

A volcanic center covering an area of about 80 km2 near Eureka, Nev., and active in the early Oligocene, is characterized by rhyolitic, rhyodacitic. and andesitic pyroclastic rocks, lava flows, and shallow intrusive bodies. These rocks were emplaced as intertonguing and interpenetrative units during a 5-m.y. interval; most of the volcanism was in the last 3 million years of this period...

No abstract available.

The possibility of using lithium in batteries to power electric vehicles and as fuel for thermonuclear power has focused attention on the limited resources of lithium other than in pegmatite minerals. The Clayton Valley, Nev., subsurface lithium brine has been the major source of lithium carbonate since about 1967, but the life of this brine field is probably limited to several more...

No abstract available.

Sphene and rutile are characteristic accessory minerals of blueschist facies metamorphic rocks. However, only sphene is present in the lowerr grade blueschist assemblages. In many areas of the world these blueschists pass into, or are in fault contact with, higher grade glaucophane schists, rutile-bearing amphibolites, and eclogites. The origin of the rutile may be related to a prograde

The analyses presented in the preceding six papers show that the geologic setting of the San Francisco Bay region has a dominant influence on potential earthquake hazards. The strong correlation between geologic conditions and the amount of earthquake damage in 1906 emphasizes the importance of this influence and demonstrates the need for seismic zonation. Seismic zonation can provide...

The least exacting demand that can be made of any model is that it serves as a device whereby we can predict actual physical happenings. Another demand which could be made is that the physical happenings predicted be in some way relevant to man, either by allowing him to anticipate future uncontrollable events or by demonstrating the possible consequences of various decisions. To date...

Reconnaissance sampling of surface and subsurface sediment to a maximum depth of 80 m below the sea floor shows that typical values of 0.03 p.p.m. and anomalies of 0.2-1.3 p.p.m. mercury have been present in northeastern Bering Sea since Early Pliocene time. Values are highest in modern beach (maximum 1.3 and mean 0.22 p.p.m. Hg) and nearshore subsurface gravels (maximum 0.6 and mean 0...

The ore deposits in the northern part of the Coeur d'Alene district are located within rocks of the Belt Supergroup that have been intruded by Cretaceous quartz monzonites. Lead-zinc-silver replacement veins constitute most of the deposits. The geometry of the district has been modified by post-ore faulting along the Osburn, Dobson Pass, and other faults. The original position of the Gem...