 | | Report (issue) | | All of these rocks are intruded by late-stage dikes that range from felsic to mafic in composition.... Paleozoic wall rocks are exposed along the north and southeast parts of the intrusive complex. A significant...significant series of Quaternary rhyolite and tuff, consisting of high-standing domes and drainage-filling...Miocene (~11 Ma) intrusive dikes that consist of granite, porphyritic rhyolite, diabase, and andesite, cross-cut...Paleozoic wall rocks that adjoin the batholith to the north and southeast. METHODS Previous bedrock mapping |  | | Journal (article/letter/editorial) | | Jurassic diorite-granodiorite laccolith and related dikes were emplaced at about 158 Ma in the northern Carlin...northcentral part of the trend at 112 Ma. Abundant Eocene dikes intruded along most of the trend and were accompanied...edge of the trend between ~40 and 36 Ma. Miocene rhyolite lavas erupted just west of and across the southern...consist predominantly of silicic to intermediate dikes, lavas, and epizonal intrusions, which we interpret...plutonic complex underlying the Carlin trend. Eocene dikes are present in most deposits, are generally altered |  | | Report (issue) | | .......8 RHYOLITE INTRUSIVE OF FIRE CENTER MINE ...........8 AGE AND ORIGIN OF THE RHYOLITE INTRUSIVE................ 21 SAMPLE 1-16 SLIGHTLY ALTERED RHYOLITE ..... 21 TABLE 16 ..............................located northwest of Marquette, Michigan in Marquette County and is within the Negaunee NW and Silver Lake Basin...study area is along County Road 510, a partially paved road off U.S. 41. Off County Road 510, access is...curve located on County Road 510 (Figure 1). Access by foot is hampered from the north by the 75 meter |  | | Journal (article/letter/editorial) | | ranging from phonotephrite (50 wt % SiO2) to rhyolite (75 wt % SiO2) in composition. Incompatible trace...associated with fluorine-rich, highly evolved rhyolite magmas (e.g. Climax, Henderson, Questa); (2) low-grade...on three porphyry Mo deposits in the southwestern USA that the sulfur in these deposits was derived from...largest of three breccia pipes situated 1· 0^1·5 km (north-)east of an alkalic, compositionally zoned intrusion...plagioclase. All these rock units are cut by rhyolite dikes containing 2^3 vol. % feldspar phenocrysts |  | | Report (issue) | | along the North Carolina – Virginia State Line Guidebook for the 1999 Meeting of the CAROLINA GEOLOGICAL...along the North Carolina – Virginia State Line Guidebook for the 1999 Meeting of the CAROLINA GEOLOGICAL...Eastern Appalachian Piedmont along Lake Gaston, North Carolina and Virginia by Paul E. Sacks 16 Porphyroblast...case study in southern Virginia and northern North Carolina by J. Wright Horton, Jr., and David L. Daniels...study along the Hollister fault zone, eastern North Carolina by David P. Lawrence 49 A field guide to |  | | Report (volume) | | ------.--. Grandview, Bounds, Fence Line, and Grant County. __________ Langford and Hines_-------____--_-...fluorspar deposit and vicinity, Burro Mountains, Grant County, N. Mex._______________________ In pocket 47. Underground...Burro Chief fluorspar mine, Burro Mountains, Grant County, N. Mex________________________ In pocket 48. Cross...Burro Chief fluorspar mine, Burro Mountains, Grant County, N. Mex._____________________________ In pocket...Burro Chief fluorspar mine, Burro Mountains, Grant County, N. Mex_____________ In pocket50. Geologic map |  | | Report (issue) | | beryl production from the Harding pegmatite, Taos County. Current drilling in the Apache Warm Springs deposit...Inc. has identified mineralized zones in altered rhyolite. The deposit is classified as volcanogenic beryllium...were discovered in the Victorio Mountains, Luna County in the early 1900s. Gulf Minerals Resources, Inc...Mountain, Otero County and in the molybdenum porphyry deposit at Questa, Taos County, although not in...granitic-rhyolite intrusions are shown in colored polygons and discussed in text. Not all rhyolite intrusions |  | | Report (issue) | | through much of the later Cenozoic, a bimodal basalt-rhyolite assemblage was erupted widely throughout the volcanic...Belknap caldera (19 m.y.) or are related to the rhyolite of Gillies Hill (9-8 m.y.). Episodic hydrothermal...bodies. Hydrothermal activity associated with the rhyolite of Gillies Hill altered and mineralized rocks...general review of the mineral deposits of Piute County, Utah. More recently, the U.S. Geological Survey...the 23-m.y.-old Osiris Tuff that crops out just north of the area of figure 2. Near Indian Creek, a monzonite |  | | Journal (article/letter/editorial) | | 927-940. 3 FIGS.. 1 PL. SEPTEMBER 1948 HIGH-POTASH DIKES IN THE HOMESTAKE MINE, LEAD, SOUTH DAKOTA BY JAMES...Black Hills Rhyolite dikes in the Homestake Mine Other occurrences of high potash dikes Origin of the...the high potash rhyolite dikes in the Homestake Mine References cited Page 927 927 928 930 934 935 938...normative mineral compositions of rhyolite dikes 2. Intersections of rhyolite dikes 3. Ternary diagram of the...Plate 1. Photomicrographs of typical sections of rhyolite from the Homestake mine Page 933 934 936 Facing |  | | Report (issue) | | UTAH U.S. GEOLOGICAL SURVEY Unexposed alkali-rhyolite stocks and possible associated ore deposits can...through much of the later Cenozoic, a bimodal basalt-rhyolite assemblage was erupted widely throughout the volcanic...Belknap caldera (19 m.y. old) or are part of the rhyolite of Gillies Hill (9-8 m.y. old). Episodic hydrothermal...bodies. Hydrothermal activity associated with the rhyolite of Gillies Hill altered and mineralized rocks...(shaded) in and adjacent to Tushar Mountains. County, Utah. More recently, the U.S. Geological Survey |  | | Report (issue) | | BULLETIN 53 Geology of Questa Quadrangle, Taos County, New Mexico BY PHILIP F. McKINLAY Geology and.............................................. 9 Rhyolite Tuffs and Flows (Tr) ..................................................................... 10 Rhyolite Intrusives (Tri) ....................................................... 11 Monzonite Porphyry Dikes (Tmp) ............................................"Geology of Costilla and Latir Peak quadrangles, Taos County, New Mexico," issued as Bulletin 42 of the State |  | | Report (issue) | | Geology of central Peloncillo Mountains, Hidalgo County, New Mexico by A. K. Armstrong, M. L. Silberman...Geology of central Peloncillo Mountains, Hidalgo County, New Mexico by A. K. Armstrong, M. L. Silberman...igneous rocks and sedimentary rocks overlain to the north and south by middle Tertiary and younger extrusive...yielding 30-33-m.y.-old K-Ar ages; 2) granite porphyry dikes and sills, which give 31-32 m.y. old K-Ar ages;...felsitic rhyolite dikes, probably related to the granite porphyry; and 4) quartz-latite porphyry dikes and |  | | Report (issue) | | Geological Survey editorial standards or with the North American stratigraphic code. Denver, Colorado ...redefinition of rocks formerly included in the Rhyolite Canyon Formation is presented in U.S. Geological...deposits and related dikes A sequence of rhyolite lava flows and tuffs, their feeder dikes, and subordinate...Gradational contacts between welded tuffs and overlying rhyolite lavas in several localities suggest that some...the lavas are rheomorphic tuffs Aphyric rhyolite lava and rhyolite tuff (Oligocene) Aphyric or sparsely |  | | Journal (article/letter/editorial) | | Madison, WI 53706, USA 2 Mail Stop 984, U.S. Geological Survey, Menlo Park, CA 94025, USA 3 Mail Stop 903...903, U.S. Geological Survey, Denver, CO 80225, USA Abstract. Plutonic rocks associated with the Latir volcanic...plutonic rocks contain abundant accessory sphene and apatite, rich in rare-earth elements (REE), as well as...are 27-28.5 Ma metaluminous basaltic andesite to rhyolite lavas, ash-flow tuffs, and hypabyssal intrusions...peralkaline Amalia Tuff and associated peralkaline rhyolite lavas (Fig. 2). The Questa caldera formed approximately |  | | Journal (article/letter/editorial) | | side of the Jurassic Goldstrike stock, along the north-northeast-striking GenPost fault system, in calc-silicate...Formation which are intruded by late Eocene rhyolite dikes. These authors synthesize district and deposit...Goldstrike stock and show that Deep Star and the rhyolite dikes are coeval and localized by dilatant faults...(Fig. 1) utilizing 40Ar/39Ar, apatite fission track (AFT), and apatite U-Th (He) dating methods. Their...(K micas) and mineralized Jurassic lamprophyre dikes provide evidence for Jurassic (>152 Ma) and Tertiary |  | | Report (issue) | | prospects of the Tyrone stock and vicinity, Grant County, New Mexico By D. C. Hedlund 1 Open-File Report...prospects of the Tyrone stock and vicinity, Grant County, New Mexico.......................... in pocket...of quartz monzodiorite crystallization, numerous dikes were intruded along east-northeast-striking fractures...faults. Some of the quartz monzodiorite porphyry dikes cut the Tyrone stock, and the dike in the vicinity...rhyolitic magmatism prevailed and the numerous rhyolite dikes and coeval plugs and sills that surround the |  | | Report (issue) | | DEPOSITS OF THE ORD MOUNTAIN DISTRICT, SAN BERNARDINO COUNTY, CALIFORNIA By F. HAROLD WEBER, JR., California...18 18 Spherulitic rhyolite Basalt 16 16 16 17 correlation and rhyolite dikes Porphyritic biotite...dacite Quartz veins Late Tertiary(?) rocks - Rhyolite-dacite flow breccia Quaternary rocks Older alluvium...area of veins ~ Northeast-central area of veins North-central area of veins _. Red Hill area of veins...Group in the north part of Ord Mountain Photomicrograph of thin section of spherulitic rhyolite Photograph |  | | Report (issue) | | Block of the Ishpeming Greenstone Belt, Marquette County, Michigan U.S. GEOLOGICAL SURVEY BULLETIN 1904-F...Block of the Ishpeming Greenstone Belt, Marquette County, Michigan By R.C JOHNSON and T.J. BORNHORST U...block of the Ishpeming Greenstone Belt, Marquette County, Michigan / by R.C. Johnson and T.J. Bornhorst... Igneous Michigan Marquette County. 3. Geology Michigan Marquette County. I. Bornhorst, Theodore J. II...III. Title: Ishpeming Greenstone Belt, Marquette County, Michigan. IV. Series. V. Series: U.S. Geological |  | | Report (issue) | | Geological Survey editorial standards nor with the North American stratigraphic code. Denver, Colorado ...fanglomerate with abundant very light gray, angular, rhyolite fragments up to 30 cm across. Upper part consists...about 300 ft (90 m) RHYOLITE OF MULE MOUNTAINS (MIOCENE) Trm Trvm Ttm Rhyolite flows Very light gray...flow-laminated, aphanitic to slightly porphyritic rhyolite; basal part of some flows consists of black vitrophyre...correlates with Mule Mountain Rhyolite of Rhodes and Smith (1973) and Rhyolite of Mule Creek (Ratt6 and Brooks |  | | Journal (article/letter/editorial) | | with mineralization are believed to be Tertiary. Dikes of granite porphyry, pegmatite, aplite, and lamprophyre...porphyry dikes Work by others 392 Pegmatite and aplite Acknowledgments 393 Lamprophyre dikes Terminology...basalt Mylonite 397 Volcanic dikes Conditions of metamorpmsm 398 Rhyolite Granite gneiss 399 Ande^^\\\^'\\\\'.... Aplite. . . . 402 Geologic structure Diabase dikes 402 General features Archean history of the Cerbat...114° 15' West, and parallels 35° 15' and 35° 30' North and lies within the mountain region of Arizona (Fig |  | | Report (volume) | | Part of the Alder Creek Mining District Custer County, Idaho GEOLOGICAL SURVEY BULLETIN 1252-A Geology...Part of the Alder Creek Mining District Custer County, Idaho By W. H. NELSON and C. P. ROSS CONTRIBUTIONS..._________________________________________________ Rhyolite. ________ __________________________________________...PART OF THE ALDER CREEK MINING DISTRICT, CUSTER COUNTY, IDAHO By W. H. NELSON and C. P. Koss ABSTRACT...monzonite, granite, leucogranite porphyry and related dikes, and volcanic rocks, all of early Tertiary age, |  | | Journal (article/letter/editorial) | | Climax-type systems; (3) the presence of porphyry rhyolite dikes, a breccia dike, and local quartz–molybdenite...of Mines, 1516 Illinois Street, Golden, CO 80401, USA e-mail: pbartos@mines.edu D. Misantoni Colorado Calumet...Calumet Company Inc., P.O. Box 1169, Golden, CO 80402, USA molybdenite; and (5) the presence of similar-appearing...rhodochrosites at Climax and other high-silica rhyolite systems. A significant difference is that unlike...A few specimens made their way to museums in the USA and Europe. A small pocket of rhodochrosite was encountered | | | Journal (article/letter/editorial) | | Climax-type systems; (3) the presence of porphyry rhyolite dikes, a breccia dike, and local quartz–molybdenite...of Mines, 1516 Illinois Street, Golden, CO 80401, USA e-mail: pbartos@mines.edu D. Misantoni Colorado Calumet...Calumet Company Inc., P.O. Box 1169, Golden, CO 80402, USA molybdenite; and (5) the presence of similar-appearing...rhodochrosites at Climax and other high-silica rhyolite systems. A significant difference is that unlike...A few specimens made their way to museums in the USA and Europe. A small pocket of rhodochrosite was encountered |  | | Report (issue) | | Fork-Jerry Peak area............. 18 Area west and north of Stanley and White Cloud Peak area.... 24 Granitic...INTRUSIVE MASSES For description see Yellowjacket area RHYOLITE INTRUSIVE MASSES For description see Yellowjacket...see description for Yellowjacket area SUNNYSIDE RHYOLITE TUFFS AND RELATED ROCKS Upper Sunnyside Tuff Red...red-brown weathering, densely welded, devitrified rhyolite tuff; multiple-flow compound cooling unit that...Reddish-gray, simple cooling unit of densely welded rhyolite tuff. Distinguished from Tsu by more abundant |  | | Journal (article/letter/editorial) | | from 16 economically mineralized occurrences in North America and China, plus 5 subeconomically Mo-mineralized...Mo-mineralized and 4 barren occurrences in North America, Norway and China. Because melt inclusions preserve...arc-related type (Cox and Singer, 1986); high-silica rhyolite–alkalic suite vs. differentiated monzogranite...associated with fluorine-rich, highly evolved rhyolite magmas, and (2) low-grade, arc-related deposits...Mesozoic and Cenozoic tectonic history of Western North America, where most porphyry Mo deposits that were |
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