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Robert C. Greene

Publications and source records attributed to Robert C. Greene.

At least 19 recordsLinked to original sources
USGS1995

Talc resources of the conterminous United States

Talc has been extracted from deposits in the United States for more than two centuries, some for dimension stone but most for ground talc products. This report is designed to summarize the current knowledge of the talc deposits and includes locations and descriptions of occurrences in 27 states, with emphasis on important producing districts. Permissive areas for additional deposits are shown and suggestions for exploration are given.

Alabama, Arkansas, California, Connecticut, Georgi↗
USGS1993

Stratigraphy of the late Proterozoic Murdama Group, Saudi Arabia

The Murdama group is in the upper part of the sequence of Proterozoic layered rocks in the Precambrian shield of Saudi Arabia. It consists of clastic sedimentary rocks and small amounts of limestone and volcanic rocks. The Murdama crops out in the eastern part of the exposed part of the shield, within 200 km of its margin. The principal outcrop area, herein designated the Afif belt, is 600 km long and has a maximum width of 80 km. Two other significant outcrop areas lying to the south are designated the Jabal Hadhah and the Mistahjed belts. The Murdama group unconformably overlies older plutonic rocks that range in composition from diorite to granite and volcanic rocks ranging from basalt to rhyolite. It is unconformably overlain in the north part of the Afif belt by sedimentary and volcanic rocks of the Jurdhawiyah group, and in many areas is intruded by younger granite. In the south part of the Afif belt the Murdama group lies in the Maslum synclinorium, a structure characterized by tight folding near its northwest margin and open folding elsewhere. To the north, the synclinorium is much broken up by faulting, particularly by left-lateral faults of the Najd system. Sections on the west flank of the Mast urn synclinorium in the south part of the Afif belt have apparent thicknesses of about 5,300 m at Jabal Murdama, 5,700 m at Jabal Raqabah, and 1 ,400 and 4,000 m at As Sawadah. The strata in these sections consist mostly of greenish-gray, very fine to coarse-grained volcanic arenite that is poorly sorted and consists of angular grains. Basal conglomerates are thin and inconspicuous, but coarse arenite, locally pebbly, predominates in the jabal Raqabah section. A prominent air-fall ash tuff caps Jabal Murdama, and an ash-flow tuff caps Jabal Raqabah. Sections on the east flank of the synclinorium have apparent thicknesses of about 2,500 m at Jabal Farida, 3,600 m at Jabal Damkh, 12,400 m at Jabal Zaydi, and 16,800 m, adjusted for folding, at Wadi Sirrah. Jabal Farida and Jabal Damkh are underlain principally by limestone of distinctive tan- and gray-weathering types, which has been named the Farida marble. Limestones of these and other colors occur in all the belts composing the Murdama and form a unifying element. The other sections consist mostly of sandstone similar to that at Jabal Murdama. Sections in the north part of the Afif belt have apparent thickness of about 3,300 and 7,600 m at Wadi Jarir, 840 m at Jabal Ajam, 534 and 1,833 m at Jabal Muwasham, about 3,800 m adjusted for folding east of jabal Silsillah, 4,900 m at Jabal Khidar, and 8,400 m at jabal umm Sammah. The Wadi Jarir section consists of sandstone very similar to that at Jabal Murdama, with thin basal conglomerate and local ash tuff. The other sections consist of conglomerate, sandstone, and siltstone. The predominance of silicic volcanic lithic grains in Murdama sandstones of the Afif belt indicates a source in a silicic volcanic belt, and discontinuous belts of such rocks lie to the southwest. Paleocurrent indicators also suggest a source from the southwest. In the north part of the belt, the lower part of the Murdama is probably a subaerial mass-movement or fluvial deposit. The strata in the rest of the belt were probably deposited at a prograding lacustrine or marine strandline. Near the northwest edge of the basin, particularly from Jabal Farida north, locally derived conglomerate was deposited and carbonate bank deposition prevailed for a time. In the jabal Hadhah belt, limestone is identical to that at Jabal Farida. It is apparently overlain by conglomerate that fines upward to sandstone and may be part of the Murdama. Structure in the Mistahjed belt is more complex and the stratigraphic sequence is less certain than in the Afif belt. Murdama rocks have been assigned to a number of formations, and traverses were made across most units. The rocks include sandstone, siltstone, limestone, conglomerate, and volcanic rock; much of the volcanic rock may not be part of the Murdama group. The source of sedimentary materials in the Mistahjed belt, as in the Afif belt, appears to be a belt of volcanic rocks lying to the southwest. The Junaynah belt of sedimentary rocks lies to the west of the Mistahjed belt. The rocks consist of basal cobble conglomerate grading up to coarse- and finegrained sandstone. These rocks have been assigned to the Murdama group in the past, but I conclude that they should be restricted from it, because their tectonic setting and age appear to be different. Radiometric ages suggest an age range of 650 to 615 Ma for the Murdama group, the laterally equivalent Hibshi formation, and the overlying Jurdhawiyah group in the Afif belt. Ages from the Mistahjed belt suggest that the Murdama rocks there are younger than 650 Ma and ages Abstract from the junaynah area suggest that the sedimentary section is younger than 61 0 Ma. The Murdama group probably was deposited in a back-arc basin on a continental platform bounded on the west by an active volcanic arc above an east-dipping subduction zone. The position of the subduction zone, which was active during most of the deposition in the Afif belt, is marked by a belt of gabbro and ultramafic rocks herein named the jabal Burqah belt. The subduction zone later stepped out to the southwest to the Nabitah belt, and Murdama strata were deposited in the Jabal Hadhah, Mistahjed, and smaller basins.

Bulletin↗
USGS1989

Mineral resources of the Mount Tipton Wilderness Study Area, Mohave County, Arizona

The Mount Tipton Wilderness Study Area (AZ-020-012/ 042) comprises 33,950 acres in Mohave County, Ariz. At the request of the U.S. Bureau of Land Management, this area was evaluated for identified mineral resources (known) and mineral resource potential (undiscovered). This work was carried out by the U.S. Bureau of Mines and the U.S. Geological Survey in 1984-87. In this report, the area studied is referred to as the "wilderness study area" or simply "the study area." There are no identified mineral resources in the study area. The southernmost part of the study area is adjacent to the Wallapai (Chloride) mining district and has low mineral resource potential for gold, silver, copper, lead, zinc, and molybdenum in hydrothermal veins. This area also has a low mineral resource potential for tungsten in vein deposits and for uranium in vein deposits or pegmatites. In the central part of the wilderness study area, one small area has low mineral resource potential for uranium in vein deposits or pegmatites and another small area has low resource potential for thorium in vein deposits. The entire study area has low resource potential for geothermal energy but no potential for oil or gas resources.

Arizona↗
USGS1985

Geochemistry of metavolcanic rocks from the Ranyah area, Kingdom of Saudi Arabia

Major-element analyses of 26 samples from seven map units of metavolcanic rocks from the Ranyah area are compared with analyses in the literature of rocks from known tectonic settings. The evidence suggests that most of the layered rocks of the Ranyah area originated in immature island arcs. The Khaniq formation originated in a continental margin setting during cratonization. The Arfan and Juqjuq formations are related to a later subduction event.

Open-File Report↗
USGS1983

Reconnaissance geology of the Al Ufayriyah quadrangle, sheet 20/42 A, Kingdom of Saudi Arabia

The Al Ufayriyah quadrangle is located in the Najd Plateau of southwestern Saudi Arabia between lat 20?30' and 21?00' N.,. long 42?00' and 42?30' E. Two-thirds of the quadrangle is underlain by Precambrian metasedimentary, metavolcanic, plutonic, and hypabyssal intrusive rocks; this area is in part mountainous and in part uneven plains. One-third is underlain by Cenozoic basalt and is part of Harrat Buqum. Flows, which surround volcanic cones, form an east-dipping surface of low relief. Precambrian metavolcanic and metasedimentary rocks are mostly metamorphosed andesite and basalt flow rocks and turfs and are divided into two principal belts in the eastern and central to western parts of the quadrangle. Plutonic rocks, which are part of the An Nimas batholith, consist of tonalite, diorite, and some quartz diorite. These rocks are postdated by younger plutonic and hypabyssal rocks that include extensive graphic granite and rhyolite, several small bodies of granite, and meta-andesite dikes. Volcanoes on Harrat Buqum are cinder cones, composite cones, shield volcanoes, and lava cones; basalt flows originating in some of the volcanoes can be traced down the slope of the harrat, and some have blocked Wadi Ranyah causing deposition of silt, sand, and gravel. Radiometric age dating of Precambrian rocks from adjacent quadrangles suggests that the layered rocks of the Al Ufayriyah quadrangle may have formed about 900 Ma ago, plutonic rocks of the An Nimas batholith 835 to 800 Ma ago, and younger plutonic rocks from 640 to 570 Ma ago. Basalts of Harrat Buqum range in age from 3.5 to 1.72 A zone in the eastern part of the quadrangle contains small gold-quartz veins, a quartz breccia reef, and a contact metasomatic iron deposit.

Open-File Report↗
USGS1983

Reconnaissance geology of the Jabal Dalfa Quadrangle, sheet 21/43 C, Kingdom of Saudi Arabia

The Jabal Dalfa quadrangle (sheet 21/43 C) is part of the Najd province in west-central Saudi Arabia. The quadrangle is mostly a plain, tilted gently northeastward, but local inselbergs and two areas of dissected uplands rise as much as 200 m above the plain. Wadi Bishah and Wadi Ranyah terminate in the quadrangle. The quadrangle is underlain by Precambrian metavolcanic, metasedimentary, and plutonic rocks. The gneiss outcrops in the northeast and east-central parts of the quadrangle are apparently the oldest rocks. After they were emplaced, a wide variety of metavolcanic and metasedimentary rocks were deposited at Jabal Dalfa and Umm Shat, and in the northeast part of the quadrangle as the Arfan formation. Subsequently, granite gneiss was emplaced in the west part of the quadrangle and intruded by gabbro. Metabasalt and meta-andesite were extruded in a wide north-trending belt through the middle of the quadrangle and at Jabal Silli. Intrusion of small bodies of granitic rocks and Najd faulting conclude the Precambrian history of the area. Surficial deposits include sand and gravel covering the plains, alluvial fans, and voluminous dune sands. In the southeast part of the quadrangle, the layered rocks strike north and dip steeply. They are oriented parallel to the Nabitah fault zone. In the northeast and east-central parts of the quadrangle, layered rocks and gneiss are sheared into slices by the southernmost faults of the major Najd fault zone. Bedding and foliation in these slices strike northwest, parallel to the faults. Gneiss in the west part of the quadrangle also strikes northwest, and dips steeply to vertically; layered rocks underlying Jabal Silli strike northeast. Layered metamorphic rocks in the Jabal Dalfa quadrangle are mostly in the greenschist facies. Projection of data from other quadrangles suggests that the oldest gneiss is about 780 Ma old and the Arfan formation, Umm Shat, and Jabal Dalfa layered rocks are about 775 to 745 Ma old. The gneiss of Shaib Hadhaq is probably about 720 Ma old, the gabbro is 640 to 625 Ma old, and the granite is about 600 Ma old. The airborne magnetometer survey suggests that considerable additional gabbro underlies the west part of the quadrangle. Concealed serpentinite bodies, particularly in the Nabitah fault zone, are also suggested. Elongate anomalies and linear gradients indicate that the northeast part of the quadrangle is probably part of the Najd fault zone. A number of gold-bearing quartz veins in the quadrangle were mined in ancient times, and on, at Jabal Umm Matirah has been drilled and found to be uneconomic. A nickel-copper prospect has proved uneconomic. geochemical survey for additional deposits of metals was completed in 1982.

Open-File Report↗
USGS1983

Reconnaissance geology of the Thaniyah Quadrangle, sheet 20/42 C, Kingdom of Saudi Arabia

The Thaniyah quadrangle, sheet 20/42 C, is located in the transition zone between the Hijaz Mountains and the Najd Plateau of southwestern Saudi Arabia between lat 20?00' and 20?30' N., long 42?00' to 42?30' E. The quadrangle is underlain by Precambrian metavolcanic, metasedimentary, plutonic, and dike rocks. Metavolcanic rocks consist of metamorphosed basalt and andesite with minor dacite and rhyolite and underlie three discontinuous northwest-trending belts. Metasedimentary rocks are confined to small areas underlain by quartzite, metasandstone, marble, and calc-silicate rock. Plutonic rocks include an extensive unit of tonalite and quartz diorite and a smaller unit of diorite and quartz diorite, which occupy much of the central part of the quadrangle. A small body of diorite and gabbro and a two-part zone of tonalite gneiss are also present. All of these plutonic rocks are assigned to the An Nimas batholith. Younger plutonic rocks include extensive graphic granite and rhyolite in the northeastern part of the quadrangle and several smaller bodies of granitic rocks and of gabbro. The metavolcanic rocks commonly have strong foliation with northwest strike and steep to vertical dip. Diorite and quartz diorite are sheared and brecciated and apparently syntectonic. Tonalite and quartz diorite are both foliate and nonfoliate and were intruded in episodes both preceding and following shearing. The granitic rocks and gabbro are post-tectonic. Trends of faults and dikes are mostly related to the Najd faulting episode. Radiometric ages, mostly from adjacent quadrangles, suggest that the An Nimas batholith is 835 to 800 Ma, gabbro and granite, except the graphic granite and rhyolite unit, are about 640 to 615 Ma, and the graphic granite and rhyolite 575 to 565 Ma old. Metavolcanic rocks similar to those hosting copper and gold mineralization in the Wadi Shuwas mining district adjacent to the southwestern part of the quadrangle are abundant. An ancient copper mine was discovered at the edge of the tonalite gneiss belt east of Wadi Ranyah. Granite and gabbro have economic potential as building stone.

Open-File Report↗
USGS1979

Reconnaissance geology of the Wadi Shuqub Quadrangle, sheet 20/41 A, Kingdom of Saudi Arabia

The Wadi Shuqub quadrangle (sheet 20/41 A) lies in the high mountainous part of the Hijaz plateau in west-central Saudi Arabia. The quadrangle is underlain chiefly by Precambrian layered metasedimentary and metavolcanic rocks that are intruded by plutons ranging in composition from gabbroic to granitic. The metasedimentary rocks include quartzite, phyllitic quartzite, phyllite, slate, argillite, granulite, schist, and marble. The metavolcanic rocks are mostly greenstone and greenstone tuff but include meta-andesite and metadacite. The rocks are in the greenschist and greenschist-amphibolite transition facies. The major plutonic rocks are tonalite and quartz diorite, which form a large batholith in the western part of the quadrangle. Smaller bodies of diorite and gabbro, granite, and complexes of mixed rocks are also present. The layered rocks are divided into sixunits that have been described in outcrop order, from east to west: 1) nearly all greenstone, 2) mixed metasedimentary and metavolcanic rocks, 3) nearly all metasedimentary rocks, 4) greenstone in eastern part, metasedimentary and metavolcanic rocks in western part, 5) nearly all metasedimentary rocks, and 6) metavolcanic rocks containing subordinate amounts of metasedimentary rocks. The layered rocks have a northerly strike throughout the quadrangle except near the southwest corner where they strike northwest. The rocks are steeply dipping to vertical. Major deformation has produced isoclinal folds and shears, strike faults, and subordinate cross faults. A second stage of deformation resulted in local open folds. Basalt of Quaternary age covers the Precambrian rocks near the eastern margin of the quadrangle, and alluvium underlies major wadis and flats. The main part of the Wadi Bidah mining district, including at least four ancient mining sites, is in the southeast part of the quadrangle. The district has produced gold from gold-quartz veins, and has some potential for producing, gold, silver, copper, zinc, and lead from massive sulfide deposits.

Open-File Report↗
USGS1976

Volcanic rocks of the McDermitt Caldera, Nevada-Oregon

The McDermitt caldera, a major Miocene eruptive center is locatedin the northernmost Great Basin directly west of McDermitt, Nev. The alkali rhyolite of Jordan Meadow was erupted from the caldera and covered an area of about 60,000 sq km; the volume of rhyolite is about 960 cubic km. Paleozoic and Mesozoic sedimentary rocks and Mesozoic granodiorite form the pre-Tertiary Basement in this area. Overlying these is a series of volcanic rocks, probably all of Miocene age. The lowest is a dacite welded tuff, a reddish-brown rock featuring abundant phenocrysts of plagioclase, hornblende, and biotite; next is a heterogeneous unit consisting of mocks ranging from basalt to dacite. Overlying these is the basalt and andesite of Orevada View, over 700 m thick and consisting of a basal unit of cinder agglutinate overlain by basalt and andesite, much of which contains conspicuous large plagioclase phenocrysts. Near Disaster Peak and Orevada View, the basalt and andesite are overlain by additional units of silicic volcanic rocks. The lower alkali rhyolite welded tuff contains abundant phenocrysts of alkali feldspar and has a vitric phase with obvious pumice and shard texture. The rhyolite of Little Peak consists of a wide variety of banded flows or welded ruffs and breccias, mostly containing abundant alkali feldspar phenocrysts. It extends south from Disaster Peak and apparently underlies the alkali rhyolite of Jordan Meadow. The quartz latite of Sage Creek lies north of Disaster Peak and consists mostly of finely mottled quartz latite with sparse minute plagioclase phenocrysts. Volcanic rock units in the east part of the area near the Cordero mine include trachyandesite, quartz labile of McConnell Canyon, and rhyolite of McCormick Ranch. The trachyandesite is dark gray and contains less than 1 percent microphenocrysts plagioclase. It is the lowest unit exposed and may correlate with part of the basalt and andesite of Orevada View. The quartz latite of McConnell Canyon is olive gray and contains about 8 percent plagioclase phenocrysts. It has an upper phase of black vitrophyre which directly underlies The alkali rhyolite of Jordan Meadow. The rhyolite of McCormick Ranch is present farther north and consists of pinkish rhyolite with small amounts of phenocrysts of alkali feldspar, quartz, and plagioclase. The alkali rhyolite of Jordan Meadow consists of interlayered aphyric, sparsely porphyritic, and abundantly porphyritic alkali rhyolites whose colors are predominantly light gray, greenish gray, and brown, respectively. Phenocrysts are alkali feldspar (to 15 percent) locally with quartz. Sections inside the caldera are as much as 360 m thick and consist of intimately interlayered gray, green, and brown alkali rhyolites commonly flow folded. Outside the caldera sections are equally thick in the south and southwest, but thinner to the north; in these places units of similar lithology are persistent for many kilometers, and flow folding is rare. A basal green porphyritic unit north of the caldera contains definite shard texture, but elsewhere this feature is rare. Nevertheless, the great lateral extent and relative thinness of the alkali rhyolite of Jordan Meadow suggests that it is welded ash-flow tuff. Overlying the alkali rhyolite of Jordan Meadow within the McDermitt caldera are four units of lavas. The rhyolite of Hoppin Peaks contains light-brownish-gray rhyolite and black vitophyre, all with sparse phenocrysts of alkali feldspar, quartz, and plagioclase. The rhyolite of McDermitt Creek is greenish or brownish gray and contains abundant phenocrysts of plagioclase. It .is in part structureless and in part flow banded. Alkali rhyolite of Washburn Creek is light gray and contains 0-5 percent phenocrysts alkali feldspar. Quartz labile of Black Mountain forms four isolated remnants of volcanoes in the south part of the caldera. It is brown where well crystallized and black where vitric and contains 5-15 percent plagioclase phenocrysts. A unit of tuffaceous sedimentary rocks in part fills the caldera. A single occurrence of andesite is interbedded.

Nevada, Oregon↗
USGS1974

Mineral resources of proposed additions to the Salmon-Trinity Alps Primitive Area, California

A mineral survey of four areas totalling 80 square miles, not included during the 1968-70 examination of the proposed Salmon-Trinity Alps Wilderness, was made by the U.S. Geological Survey and U.S. Bureau of Mines in 1973. Geological Survey personnel mapped the geology and collected stream-sediment and rock samples for spectrographic and chemical analysis; Bureau of Mines personnel examined the known placer and lode claims. The areas examined include: (1) the upper drainage of Red Cap Creek in Humboldt County, adjoining the northwest part of the Salmon-Trinity Alps Primitive Area; (2) an area in Trinity County south of the Primitive Area including the drainage of Big French Creek and the canyon of North Fork Trinity River from Hobo Gulch Forest Camp to the junction with East Fork of North Fork; (3) an area, also south of the Primitive Area and in Trinity County, including East Fork of North Fork from Manzanita Flat to Squaw Gulch, and the drainages of Indian Creek, Squaw Gulch, lower East Branch, and lower Yellow Jacket Creek; (4) the drainage of St. Clair Creek in Siskiyou County north of the Primitive Area; and (5) a small area on New River from the junction of Slide and Virgin Creeks downstream to the mouth of Barron Creek that was previously mapped by the Geological Survey (Hotz and others, 1972) but had not been studied by the Bureau of Mines.

California↗