David A Lindsey (Former Employee)

The U-Pb isotope systematics of uraniferous opals from Spor Mountain, Utah, were investigated to determine the suitability of such material for geochronologic purposes, and to estimate the timing of uranium and associated beryllium and fluorine mineralization. The results indicate that uraniferous opals can approximate a closed system for uranium and uranium daughters, so that dating...

No abstract available.

The Thomas Range and northern Drum Mountains have a history of volcanism, faulting, and mineralization that began about 42 m.y. ago. Volcanic activity and mineralization in the area can be divided into three stages according to the time-related occurrence of rock types, trace element associations, and chemical nature of mineralization. Volcanic activity switched abruptly from rhyodacite...

The Blue Ribbon lineament is an east-west structural zone that is about 25 kilometers wide and passes through the Pioche mineral belt at about 38°10' N. It is best known in Utah, where it is at least 190 km long, and extends from the southern Sevier Plateau in the High Plateaus westward and across southern Mountain Home (Needle) Range in the Great Basin. It probably continues westward an

This report describes the differential array, of seismometers recently installed at the Hollister, California, Municipal Airport. Such an array of relatively closely spaced seismometers has already been installed in El Centro and provided useful information for both engineering and seismological applications from the 1979 Imperial Valley earthquake. Differential ground motions...

A mineralized area near Blawn Mountain in the southern Wah Wah Range has potential for deposits of lithophile metals, including uranium, tin, molybdenum, and beryllium. An area of iron oxide, alunite, and kaolinite alteration in rhyolite on Blawn Mountain overlaps southward with an area of fluorite, montmorillonite, and illite alteration in rhyolite and breccia near the Staats mine. The...

Epithermal beryllium deposits in western Utah have distinctive geological and geochemical associations that provide guides to exploration for new resources of beryllium and associated metals. Beryllium deposits at Spor Mountain and the Honeycomb Hills are uniquely associated with topaz-bearing rhyolite of Late Tertiary age and are restricted to porous water-laid tuff and breccia that...

Twenty-six new age determinations by the fission-track method establish a chronology for volcanism, intrusion, and mineralization in the Thomas Range, Keg Mountain, and Desert Mountain, in western Utah. The fission-track ages confirm D. R. Shawe's three-fold classification of igneous rocks. The oldest group of rocks consists of flows, agglomerates, and some ash-flow tuffs that were...

The middle Precambrian Moeda Formation of Minas Gerais, Brazil, contains uranium and other minerals believed to be of detrital origin. Two areas of anomalously high concentrations of uranium have been discovered in conglomeratic zones that are interpreted as paleochannels. Because the distribution of uranium is believed to be controlled at least in part by sedimentation, a reconnaissance...

No abstract available.

No abstract available.

No abstract available.