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W.C. Overstreet

Publications and source records attributed to W.C. Overstreet.

18 recordsLinked to original sources
USGS1987

Minor elements in magnetic concentrates from the Syenite-Shonkinite Province, southern Asir, Kingdom of Saudi Arabia

Magnetic concentrates from 106 localities in three plutons of syenite and one pluton of shonkinite in the southern Asir were analyzed spectrographically for 31 elements to determine if anomaly-enhancement techniques would identify mineralization not disclosed by conventional geochemical sample media. Positive anomalies are lacking for all elements except vanadium. Vanadium contents as high as 0.7 percent were identified in magnetic concentrates from the syenite pluton to the southeast of Suq al Ithnayn, but magnetite is sparse. This observation indicates a need to reexamine magnetite-rich drill core for possible ore-grade tenors in vanadium from the zoned pluton at Lakathah. Experimental analyses for platinum-group metals in magnetic concentrates from layered mafic plutons at Jabal Sha'i', Jabal al Ashshar, and Hishshat al Hawi should be performed to determine whether micron-size particles of the platinum-group metals are present in mafic rocks of the Arabian Shield.

Open-File Report↗
USGS1985

Engineering-geology site appraisal of the Federal Capital Territory, Nigeria

The 7,700-km 2 -area Federal Capital Territory, Nigeria, is underlain by crystalline igneous and metamorphic rocks of Precambrian age. Sandstone and claystone of Cretaceous age overlie Precambrian rocks in the southwestern part of the Territory. Laterite caps many hills of Cretaceous rock, some hills of Precambrian rock, and crops out near stream banks in the east and northeast. The most conspicuous structural features are a broad “J”-shaped fold traversing the eastern and central part of the Territory and a north-trending shear zone along the eastern boundary. The soils of the Territory are lateritic and belong to the SW-SP-SM (Unified Soil Classification System) groups covering Precambrian migmatites gneisses and granites and the SC group covering Cretaceous sediments and Precambrian mica-rich schists. The average penetrometer shear strength of the soil is 3.11 bars. The engineering characteristics of the rocks are (1) medium- to high-strength massive and gneissic rock, (2) low-to medium-strength bedded rock, and (3) low-strength foliated and sheared rock. An area of at least 800 km 2 is free from apparent geological hazards and should be suitable for construction of a capital city, its environs and supporting facilities.

Bulletin of the International Association of Engin↗
USGS1985

Review of the use of magnetic concentrates in geochemical exploration

Magnetic concentrates recovered readily by hand magnet from alluvial sediments or panned concentrates have been used successfully in exploration as a geochemical sample medium for Cu, Zn, Co, Cr, Mo, Ni, V, Sn, and Be, particularly in arid environments where alluvial sediments may be contaminated by aeolian debris. Opportunity for this use arose recently as chemical and spectrographic techniques were developed to determine the abundances of a variety of trace elements in Fe-rich media. The use of analytical data from magnetic concentrates was introduced as one of several anomaly-enhancement techniques based on heavy minerals and intended to identify blind ore deposits. An extensive literature, reviewed here, on the relation of the chemical composition of the mineral magnetite, a main component of magnetic concentrates, to geologic conditions of origin, facilitates the interpretation of trace-element data in the context of association with ore deposits.

Open-File Report↗
USGS1982

Geochemical orientation for mineral exploration in the Hashemite Kingdom of Jordan

This report is a supplement to previous accounts of geochemical exploration conducted in the Hashemite Kingdom of Jordan by the Natural Resources Authority of the Royal Government of Jordan and the U.S. Geological Survey. The field work on which this report is based was sponsored by the U.S. Agency for International Development, U.S. Department of State. Procedures used in collecting various kinds of rocks, ores, slags, eluvial and alluvial sediments, heavy-mineral concentrates, and organic materials for use as geochemical sample media are summarized, as are the laboratory procedures followed for the analysis of these sample materials by semiquantitative spectrographic, atomic absorption, fluorometric, and X-ray diffraction methods. Geochemical evaluations of the possibilities for economic mineral deposits in certain areas are presented. The results of these preliminary investigations open concepts for further use in geochemical exploration in the search for metallic mineral deposits in Jordan. Perhaps the most desirable new activity would be hydrogeochemical exploration for uranium and base metals, accompanied by interpretation of such remote-sensing data as results of airborne radiometric surveys and computer-enhanced LANDSAT imagery. For more conventional approaches to geochemical exploration, however, several fundamental problems regarding proper choice of geochemical sample media for different geologic and geographic parts of the Country must be solved before effective surveys can be made. The present results also show that such common geochemical exploration techniques as the determination of the trace-element contents of soils, plant ash, and slags have direct application also toward the resolution of several archaeological problems in Jordan. These include the relation of trace-elements chemistry of local soils to the composition of botanic remains, the trace-elements composition of slags to the technological development of the extractive metallurgy of copper and iron in the region, and the use of charcoal from slags for the C-14 dating of periods of archaeometallurgical activity. Less directly, interpretations based on the distribution in time and space of the archaeometallurgical activities of the region might add to the knowledge of early climatic conditions and vegetative cover of the area.

Open-File Report↗
USGS1978

Tin and related elements in sediments and beach sands from Afghanistan, Iran, and Turkey

Sixty samples of sediments from stream beds, outwash plains, and beaches were collected in Afghanistan, Iran, and Turkey by Fred L. Klinger, U.S. Bureau of Mines, as part of the field work undertaken by the National Geographic-Smithsonian Pyrotechnological Expedition of 1968. Facilities for the analysis of the samples for tin and other metals were not immediately available, but in 1973 arrangements were made for analyses to be made on a time-permitting basis in the U.S. Geological Survey. The original purpose in collecting the samples was to determine whether tin was present in amounts indicative of sources for tin ores used in antiquity for the manufacture of bronze. The results of the analyses not only permitted an evaluation of the potential for tin in the localities sampled, but also afforded chemical and mineralogical data that were interpretable in the context of regional potential for other elements of current industrial use. These include gold, base metals, ferro-alloy metals, beryllium, rare earths, and barium. The original 60 samples of sand were sieved to make three size fraction (>0.707 mm, <O.707->O.177 mm, and <0.177 mm) for spectrographic and chemical analysis. Splits of these fractions were used for replicate analyses to permit evaluation of the precision of the analytical procedures. Further splitting of the <0.707->0.177 mm sand gave fractions from each sample that were separated in bromoform. Concentrates from the heavy-liquid separations were divided magnetically into six parts from most magnetic to least magnetic. These concentrates were analyzed spectrographically. The precision of the spectrographic analyses is well within the limits of precision expected from semiquantitative procedures. Such precision allows semiquantitative spectrographic procedures to be used with confidence as a valuable tool for reconnaissance investigations in which multi-element analyses are necessary. The analyses of the various fractions of sediments and sediment concentrates indicate the sample media in which an element was most likely to occur. Tin exhibited no preferential concentration into any particular medium. However, many elements with which tin is associated, and other elements of industrial use, do concentrate into one or more of the sample media. This indication of a preferred medium permits interpretation of the analyses as to the best sample medium for a particular element in the environment of western Asia. Cassiterite and/or tin were detected in many samples from Afghanistan, Iran, and Turkey, but in most of the samples the tin was present in normal crustal abundance. Sixteen samples, including seven from Afghanistan, eight from Iran, and one from Turkey contain unusually large amounts of tin. The most notable areas of anomalous tin are near Mirzaka, Qala-i-Asad, and Shah Agha in Afghanistan; near Meshed, Shir Kuh, Natanz, Nodus, and Talmesi in Iran; and on the shore of the Balck Sea just west of Trabzon in Turkey. Even in these localities the tin appears to be a minor element associated with other ores. The most common association of tin is with copper at known mineralized areas. This relation may have historical significance in the context of the development of bronze. The results of the analyses provided geochemical data on the distribution of other elements of industrial use and clearly identified nine of the ten known mineral deposits represented by the samples. The known metallization at the reported deposits may be only a part of more complex groups of metals. In Afghanistan an array of anomalous elements at the known gold placers around Mirzaka and along the Anguri River signals the presence of complex ore deposits. These elements are silver, arsenic, gold, bismuth, cadmium, copper, mercury, indium, molybdenum, lead, antimony, tin, thallium, tungsten, and zinc. They may indicate a Carlin-type gold deposit in which the wall-rocks are enriched in micron-sized particles of gold. Other localities in Afghanistan signalled by the results of the analyses to be anomalous and to merit further geochemical exploration are: (1) a reach of the Panjshir River for beryllium, lead, zinc, chromium and nickel; (2) the area near Bamian for beryllium; (3) the Siakhak village area for gold and copper; (4) around Qala-i-Asad and Shah Agha for lead, zinc, gold, and tungsten. Some attention to the distribution of monazite around Siakhak, Shahjui, Qala-i-Asad, and Shah Agha is justified to determine if this ore mineral for the rare earths and thorium is enriched over its normally expectable trace as an accessory mineral in granitic rocks, pelitic schists, and gneisses. In Iran, the pluton of granodiorite porphyry near Sar Cheshmeh, an area where a huge porphyry copper deposit was being investigated by the Geological Survey of Iran when the present samples were collected in 1968, shows as a strong geochemical anomaly for copper and molybdenum. The granitic area near Meshed is geochemically enriched persistently in beryllium, tin, and barium, and locally in gold, lanthanum, niobium, yttrium, and other elements. This area deserves a thorough regional geochemical survey for beryl and nonberyl sources of beryllium, for fluorite, and for the ores of niobium, tin, barium, the rare earths, and thorium. Other localities in Iran that merit geochemical exploration on the basis of these data are: ;1) the areas between Tabas and Deyhuk, east of Naiband, and south of Naiband for barium and zinc; (2) a locality about midway between Kerman and Sirdjan for barium, lanthanum, strontium, and zinc; (4) the Meskani copper mine area for mercury, lead, and nickel as well as copper; (5) the Talmesi copper mine area for such other elements as barium, cobalt, mercury, strontium, and zinc; (6) a small pluton of granodiorite north of Natanz for tungsten and base metals; (7) the vicinity of Zendjan for auriferous polymetallic sufide deposits; (8) gold in the gorge 15 km east of Miyaneh; and (9) the area near Nodus for gold, base metals, molybdenum, and niobium, and possibly uranium. The Harsit River basin in Turkey appears to be a suitable target for geochemical exploration for gold and low-temperature hydrothermal deposits of base metals, barium, and mercury.

Open-File Report↗
USGS1977

Data from geologic investigations in the Yemen Arab Republic during 1976

The results of semiquantitative spectrographic analyses for 31 elements in 126 specimens of rocks from the Yemen Arab Republic, collected mainly during February 1976 from the Precambrian area in the southeastern part of the country, provide background data for use in geochemical evaluation of areas potentially favorable for mineral deposits. Gold and thorium were undetected; the lower limits of determination are 10 parts per million (ppm) and 20 ppm, respectively. For the other elements, the abundances follow geochemical norms for crustal distribution: (1) Fe, Nb, and Zr in Holocene weathering products; (2) Ca and Sr in Pliocene limestone; (3) Mo in Pliocene(?) or Miocene(?) dikes; (4) Be, La, and Sn in Miocene(?) alkalic granite; (5) As, Be, and La in Tertiary and/or Cretaceous felsic tuff; (6) V in Tertiary and/or Cretaceous carbonaceous sedimentary rocks interbedded with volcanic rocks; (7) Be, La, Sn, and Zr in Tertiary and/or Cretaceous undivided volcanics; (8) Sn and W in Precambrian felsite and pegmatite; (9) Co, Cr, Ni, and Ti in Precambrian mafic rocks; (10) Mg and Sr in Precambrian marble and calcsilicate rocks; (11) Y in Precambrilan schist; (12) B and Sc dispersed in rocks of many ages; and (13) Ag, Ba, Bi, Cd, Cu, Mn, Pb, Sb, Sn, and Zn in a hydrothermal replacement deposit in Precambrian sediment. None of the rocks contained as much as 205 ppm equivalent uranium. The highest values for Ag, Cu, Pb, Zn, and Cd were obtained on a sample of hydrothermally altered siltstone not personally collected by the writers. It was said to have come from the Ma'rib area in the eastern part of the Yemen Arab Republic. The source must be studied, because this single sample is high-grade base-metal ore. Among the samples collected by the writers, the economically most significant are altered tuffs, ignimbrites, and felsites exposed between Jibal Hufash and Manakhah on the road from Hudaydah to San'a'. They are strongly anomalous for As and weakly anomalous, variously, for Hg, Mo, and Pb, which elements may constitute an epigenetic dispersion pattern from hidden sulfide deposits. Inasmuch as chalcopyrite and native copper have been reported in the vicinity of Jabal Haraz in the Manakhah area, the rocks of the Yemen Volcanics in this region should be explored for base-metal sulfide deposits. The first results of paleontologic examinations of fossils collected during 1975 and 1976 are presented, as are a list of Landsat images covering the Yemen Arab Republic, and a selected bibliography of reports on geology and the allied sciences relating to the Yemen Arab Republic.

Open-File Report↗
USGS1977

Black monazite from Taiwan

Two forms of detrital monazite are known in offshore bars in southwestern Taiwan: a yellow-green to colorless form and an unusual but abundant pelletlike form, generally black but also colored gray or brown. These black pellets, which are about 160 by 200 microns in size, are composed of fine-grained monazite crystals from 2 to 20 microns in size. The pellets are associated with highly variable amounts of discrete grains of detrital quartz, rutile, amphibole, tourmaline, and other minerals. Intergrown with the monazite are quartz, a cerium oxide mineral, chlorite, sulfides, and other minerals. Opaqueness of the pelletlike monazite is due principally to the cryptocrystalline nature of part of the monazite; only a small part of the opaqueness can be attributed to opaque inclusions. The black pelletlike monazite lacks thorium and has a high content of europium. In this respect, as in color, shape, size, and inclusions, the pelletlike monazite differs from the yellow-green detrital monazite. Despite the fact that they occur together in the littoral placers, they appear to have had different origins. The yellow-green monazite originated as an accessory mineral in plutonic rocks and has accumulated at the coast through erosion and transport. The origin of the pelletlike monazite is as yet unknown, but it is here inferred that it originated in unconsolidated coastal plain sediments through migration of cerium from the detrital monazite during weathering, and of the intermediate weight mobile rare earths from clay minerals during diagenesis. Possibly these pelletlike grains are detrital particles formed through erosion and transport from originally larger aggregates cemented by diagenetic monazite.

Proceedings of the Geological Society of China↗
USGS1972

Reconnaissance geology of the Jabal Bitran quadrangle, Kingdom of Saudi Arabia

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, and a western area of dominantly pelitic chlorite-sericite schist, separated by the narrow central complex of the Idsas Range. This complex is composed of pyroclastic rocks, lava, conglomerate, marble, and plutonic mafic rocks that have been intricately modified by episodes of metamorphism, igneous intrusion, and faulting. The Idsas Range contains ancient gold and copper mines, and deposits of magnetite, copper, asbestos, and chromite. The rocks in the Jabal Bitten quadrangle are here interpreted to consist of three major sedimentary and volcanic groups, the lowermost of which was deposited unconformably on hornblende-biotite granite gneiss, and all of which are intruded by granite dikes and plutons. From oldest to youngest the layered rocks are called Halaban Group, Bi'r Khountina Group, and Murdama Group, A biotite-hornblende granite is older than uppermost Bi'r Khountina, and peralkalic granite is younger than Murdama. The layered rocks of these groups are generally metamorphosed to the greenschist facies. The metamorphic grade rises abruptly at the Idsas Range to the albite-epidote-amphibolite facies and lower subfacies of the amphibolite facies in parts of the Halaban Group; some skarn east of the range may be in the upper part of the amphibolite facies. Characteristically, the Halaban Group has the highest grade and the greatest range in metamorphic grade, and the Murdama Group has the lowest but most uniformly developed metamorphic grade. The metamorphism of the rocks was caused by three successive pulses of regional dynamothermal metamorphism plus contact metamorphism around the younger bodies of plutonic igneous rocks. Four major structural elements of the quadrangle are reflected in the geography and geologic units. These are a mantled gneiss dome on the east separated from a north-plunging synclinorium in rocks of the Murdama and Bi?r Khountina Groups on the west by a narrow dejective zone of the Halaban and lower Bi?r Khountina. The dejective zone is much modified by impricate overthrusts and accompanying tear faults. These major faults have pushed elements of the Halaban and Bi?r Khountina westward over Bi?r Khountina and Murdama, with the result that very complex fault patterns have evolved. Open geochemical reconnaissance of the area disclosed one positive anomaly for nickel and 40 threshold indications of several elements, principally nickel, chromium, copper, and tungsten. Heavy-mineral and radiometric reconnaissance showed 18 areas containing scheelite and/or powellite and four areas of anomalous radioactivity. Most of these features are in the dejective zone, as are five of the nine ancient workings, the massive and disseminated magnetite, most of the secondary copper minerals, and the traces of asbestos, magnesite, and chromite known in the quadrangle. The mantled gneiss dome and a complex of gabbro and amphibolite on its southwestern flank are the next most mineralized areas. Scant evidence of mineralization is present in the Murdama Group west of the dejective zone. Magnetite deposits at Jabal Idsas have the greatest potential of the mineral deposits in the Jabal Bitran quadrangle. Further study of gold at Fawara and Selib mines is recommended, as is investigation of a positive nickel anomaly that shows threshold cobalt and above background radioactivity. The garnetiferous skarn in the east-central part of the quadrangle should be examined for composition and abrasive character of the garnet and for the remote possibility of tungsten in scheelite and beryllium in helvite.

Open-File Report↗
USGS1953

Progress report of southeastern monazite exploration, 1952

Reconnaissance of placer monazite during the field season of 1952 covered 6,600 square miles drained by streams in the western Piedmont of Virginia 5 North Carolina, South Carolina,, and Georgia. Emphasis during this investigation was placed on the area between the Savannah River at the border of South Carolina and Georgia and the Catawba River in North Carolina because it contains most of the placers formerly mined for monaziteo Four other areas along the strike of the monazite-bearing crystalline rocks were also studied, They center around Mt. Airy, N.C., Athens, Ga. Griffin, Ga. and LaGrange, Ga. In the Savannah River Catawba River district, studies indicate that even the highest grade stream deposits of more than 10 million cubic yards of alluvium contain less than 1 pound of monazite per cubic yard. The average grade of the better deposits is about 0 0 5 pound of monazite per cubic yard. Only trace amounts of niobium, tantalum, and tin have been detected in the placers. Tungsten is absent. Locally gold adds a few cents per cubic yard to the value of placer ground. The best deposits range in size from 1 to 5 million cubic yards and contain 1 to 2 pounds of monazite to the cubic yard. Hundreds of placers smaller than 1 million cubic yards exceed 2 pounds of monazite to the cubic yard and locally attain an average of 10 pounds Monazite deposits around Athens, Ga., are similar to the smaller deposits in the central part of the Savannah River - Catawba River district. A few small very low-grade monazite placers were found near Mt. Airy, N.C., Griffin, Ga., and LaGrange Ga., but they are of no economic value. The larger the flood plain and the farther it lies from the source of the stream, the lower is the monazite content of the sediment. Monazite cannot be profitably mined .from the crystalline rocks in the five areas. The alluvial placers are in stream sediments of post-Wisconsin age. Some pre-Wisconsin terrace gravel of small areal extent is exposed but it contains only a small amount of monazite Pre-Wisconsin to early post-Wisconsin colluvial sediments locally contain 2 pounds of monazite to the cubic yard. Mode of presentation of reports covering field work during the seasons of 1951 - 52 is given. No further reconnaissance will be undertaken, in the western monazite belt.

Georgia;North Carolina;South Carolina;Virginia↗