Search Results

No abstract available....

This report summarizes the geology of an area of some 6000 square kilometers in the northern part of the Central Cordillera of the Colombian Andes. The area, in north-central Department of Antioquia, was mapped between 1964 and 1968 as part of the Inventario Minero Nacional (IMN) project. Mineral resources are...

The Stillwater Complex contains the largest potential chromite and platinum metal resources and second largest nickel resources in the United States. The Ultramafic zone has produced about 900,000 long tons of chromite concentrate and contains unmined reserves equivalent to 2,520,000 long tons of Cr2O3. Nickel and copper sulfide minerals that...

The work on this volume began in January 1972, but in a broader sense its production began many years ago. The chapters were written by geologists most of whom have had many years of experience studying the geology of mineral deposits, and more particularly the commodities about which they have...

Quantitative study of intrinsic inhomogeneities in native gold grains from three deposits in the western United States has revealed concentration profiles that represent the integrated sum of natural diffusion plus original chemical heterogeneity. By assuming that measured natural concentration gradients result solely from diffusion, upper limits may be placed on...

No abstract available....

No abstract available....

A pyrite-bearing latite porphyry that contains fragments of syenite and a quartz porphyry intruded into the Cretaceous Cox Sandstone are well exposed in a roadcut at Texan Mountain, Hudspeth County, Tex. The pyrite, which occurs along tiny fractures as well as disseminated, and the multiple episodes of intrusion, coupled with copper minerals in veins in...

The data of Rau (1967) on the H 2 S/H 2 ratios of gas in equilibrium with high digenite solid solutions permit the calculation of the activity of Cu 2 S as a function of temperature and composition. The activity of Cu 2 S falls to 0.5 when the mole fraction (in the system Cu 2 S-S) drops only to...

No abstract available....

A geochemical exploration program aimed at determining regional patterns of metal distribution as well as pinpointing areas likely to contain undiscovered ore deposits was carried out in north-central Okanogan County, Washington. About 1,000 gully and stream sediment samples were collected from a rectangular area of about 800 square miles. The...

The Bi'r al Badriyah quadrangle covers an area of 2843 sq km in the extreme eastern part of the Precambrian Shield in central Saudi Arabia. The Precambrian rocks in the southeastern part of the area are unconformably overlain by limestone of Permian age, which occupies only a small part of...

The junction of several major structures and stratigraphic sequences is in the Konakpinar-Sarica area of central Turkey. Most of the area is underlain by Upper Jurassic to Cretaceous limeston and siltstone, early Tertiary sedimentary rock, and remnants of younger volcanic rocks and lacustrine deposits. The northeastern part of the area,...

As a result of geologic studies and geochemical reconnaissance by Griffitts, Albers, and brier in 1969 in the Ergani-Maden district of eastern Turkey, seven areas were recommended for more detailed investigation. Two of these, here termed Areas 1 and 2, were mapped geologically and sampled geochemically in June and July...

Maps showing the distribution of anomalous amounts of selected elements found in more than 1,600 stream-sediment and more than 1,500 rock samples have been prepared form results of semiquantitative spectrographic analyses. The samples were collected in the Eagle quadrangle, east-central Alaska, in the summers of 1968, 1969, 1970, and 1971. Figure...

Detailed geologic and geochemical studies of the four 7½-minute quadrangles that make up the Edna Mountain 15-minute quadrangle in Humboldt County, Nevada, were begun during the 1969 summer field season. The objectives of the project are to map the geology of this structurally complex area at 1:24,000 scale and to...

No abstract available....

The Jabal Bitten quadrangle covers an area of 2833 sq km in the eastern part of the Precambrian Shield in Saudi Arabia. The rocks in the quadrangle are divided geographically alone arcuate north-trending lines into an eastern area of granite intruded by a swarm of dikes of rhyolite and andesite,...

Geologic and radiometric studies and chemical analyses of soils, rocks, and water were made north of an area between Edgemont and Hot Springs, South Dakota.The soil is shallow, poorly developed, and not present in some areas. The median pH of the soil from three areas ranges from 6.7 to 7.0....

A reconnaissance of portions of the Northwestern Hijaz quadrangle in the Kingdom of Saudi Arabia was made during 1964 and 1965 as part of a mineral survey of the Precambrian crystalline rocks of the country. The survey is being made under the terms of an agreement between the Saudi Arabia...