Gold mineralisation near the Main Divide, upper Wilberforce valley, Southern Alps, New Zealand

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Becker, J.A.; Craw, D.; Horton, T.; Chamberlain, C.P.

2000-01-01

Veins up to 8 m wide fill extensional fractures in Torlesse Terrane metasediments near the Main Divide in the upper Wilberforce valley, Canterbury, New Zealand. The upper Wilberforce veins are part of a prominent 40 km long, NNE-trending swarm of gold-bearing veins formed across the Main Divide during the Late Cenozoic rise of the Southern Alps. The veins occur within, and near, a prominent set of faults which constitute the Main Divide Fault Zone. The veins are irregular in shape due to contrasting host rock properties, and have been only weakly sheared and deformed. Veins cut across greywacke beds and follow irregularly along argillite beds, on the 1-10 m scale. Quartz dominates vein mineralogy, but albite forms up to 45% of some veins, and minor chlorite, pyrite, arsenopyrite, chalcopyrite, and gold occur sporadically, especially in breccias near vein margins. Fluid inclusions in vein quartz homogenise at 180-253 degrees C, and arsenopyrite composition (28.3-30.8 at.% As) suggest formation temperatures of 250-350 degrees C. Elevated arsenic levels (up to 200 ppm above a background of 10 ppm) in some host greywackes and argellites suggest that hydrothermal activity pervaded host rocks as well as forming veins, but there is no textural evidence for this fluid flow. Late-stage carbonates in faults adjacent to the quartz veins, but which postdate the quartz veins, have δ 18 O ranging from 11.1 to 25.6 per thousand, and δ 13 C ranging from -12.5 to -1.1 per thousand. These carbonates were deposited by a mixture of meteoric and crustally isotopically exchanged fluid as a shallow-level manifestation of the same hydrothermal system which deposited the quartz veins. The upper Wilberforce veins structurally and mineralogically resemble some Late Cenozoic gold-bearing vein systems in the Mt Cook area, 100 km to the southwest along the Southern Alps. (author). 52 refs., 9 figs., 3 tabs

Origin of ore-forming fluids of the Haigou gold deposit in the eastern Central Asian Orogenic belt, NE China: Constraints from H-O-He-Ar isotopes

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Zeng, Qingdong; He, Huaiyu; Zhu, Rixiang; Zhang, Song; Wang, Yongbin; Su, Fei

2017-08-01

The Haigou lode deposit contains 40 t of gold at an average grade of 3.5 g/t, and is one of the largest deposits in the Jiapigou gold belt located along the eastern segment of the northern margin of the North China Craton. The deposit comprises 15 gold-bearing quartz veins hosted in a Carboniferous monzonite-monzogranite stock. Cretaceous dikes consisting of diorite, diabase, and granodiorite porphyries are well developed in the deposit. The diorite porphyry dikes (130.4 ± 6.3 Ma) occur together with gold-bearing quartz veins in NNE- and NE-striking faults. Gold-bearing quartz veins crosscut the diorite porphyry dikes, and the veins are in turn crosscut by E-W-striking 124.6 ± 2.2 Ma granodiorite porphyry dikes. The mineralization mainly occurs as auriferous quartz veins with minor amounts of sulfide minerals, including pyrite, galena, chalcopyrite, and molybdenite. Gold occurs as either native gold or calaverite. Common gangue minerals in the deposit include quartz, sericite, and calcite. The deposit is characterized by various types of hydrothermal alteration, including silicification, sericitization, chloritization, potassic alteration, and carbonatization. Three stages of hydrothermal activity have been recognized in the deposit: (1) a barren quartz stage; (2) a polymetallic sulfide (gold) stage; (3) a calcite stage. Fluid inclusions in hydrothermal pyrites have 3He/4He ratios of 0.3 to 3.3 Ra and 40Ar/36Ar ratios of 351 to 1353, indicating mixing of fluids of mantle and crustal origin. Hydrothermal quartz yielded δ18O values of -1.3‰ to +7.2‰ and δD values of fluid inclusions in the quartz vary between -80‰ and -104‰. These stable isotope data also suggest mixing of magmatic and meteoric fluids. Noble gas and stable isotopic data suggest that the ore fluids have a predominant mantle source with a significant crustal component. Based on the spatial association of gold-bearing quartz veins with early Cretaceous intrusions, and the H-O-He-Ar isotopic

Geology, geochemistry, and geochronology of the East Bay gold trend, Red Lake, Ontario, Canada

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Gallagher, Shaun; Camacho, Alfredo; Fayek, Mostafa; Epp, Mark; Spell, Terry L.; Armstrong, Richard

2018-01-01

The Red Lake greenstone belt is situated in northwestern Ontario within the Uchi Subprovince, Superior Province. Most gold deposits therein are associated with major deformation corridors; the east-west oriented "Mine trend" hosts most of the large deposits and the northeast-southwest "East Bay trend" hosts several small deposits and showings. Gold along the East Bay trend typically occurs in quartz replacement veins that were emplaced into pre-existing quartz-carbonate veins. Gold can occur as free gold or along vein margins associated with pyrite and pyrrhotite. Most primary fluid inclusions, preserved in relatively undeformed portions of veins, are carbonaceous with lesser quantities of aqueous inclusions. The average homogenization temperature of aqueous fluids is 250 °C; however, the abundance of three-phase inclusions, variation in liquid-vapor ratios, and a wide range in homogenization temperatures indicate that immiscibility, effervescence, and fluid mixing are mechanisms associated with gold deposition. The age ( 2550 Ma) of alteration minerals in the Abino area is considerably younger (by 100 Myr) than alteration minerals in other deposits in the Red Lake district, indicating that the mineralizing fluid history was more protracted than previously thought. Along the East Bay trend, barren veins generally have lower δ18OVSMOW values (0.0 to 8.5‰) relative to auriferous veins (9.6 and 13.1‰). Consequently, the oxygen isotopic composition of quartz could be used as a vector for gold mineralization. The genetic model for the East Bay trend involves several stages of vein formation. Auriferous veins formed near the upper boundary of the mesozonal regime (depth of 5-6 km).

Flash vaporization during earthquakes evidenced by gold deposits

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Weatherley, Dion K.; Henley, Richard W.

2013-04-01

Much of the world's known gold has been derived from arrays of quartz veins. The veins formed during periods of mountain building that occurred as long as 3 billion years ago, and were deposited by very large volumes of water that flowed along deep, seismically active faults. The veins formed under fluctuating pressures during earthquakes, but the magnitude of the pressure fluctuations and their influence on mineral deposition is not known. Here we use a simple thermo-mechanical piston model to calculate the drop in fluid pressure experienced by a fluid-filled fault cavity during an earthquake. The geometry of the model is constrained using measurements of typical fault jogs, such as those preserved in the Revenge gold deposit in Western Australia, and other gold deposits around the world. We find that cavity expansion generates extreme reductions in pressure that cause the fluid that is trapped in the jog to expand to a very low-density vapour. Such flash vaporization of the fluid results in the rapid co-deposition of silica with a range of trace elements to form gold-enriched quartz veins. Flash vaporization continues as more fluid flows towards the newly expanded cavity, until the pressure in the cavity eventually recovers to ambient conditions. Multiple earthquakes progressively build economic-grade gold deposits.

Genesis of the hydrothermal gold deposits in the Canan area, Lepaguare District, Honduras

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Mattioli, Michele; Menichetti, Marco; Renzulli, Alberto; Toscani, Lorenzo; Salvioli-Mariani, Emma; Suarez, Pedro; Murroni, Alessandro

2014-04-01

The Canan area (Honduras) is characterized by a gold-bearing ore deposit that is associated with quartz-veined shear zones. Gold mineralization occurs in low-to medium-grade metamorphic host-rocks (graphitic and sericitic schists). Hydrothermal fluids, which are associated with the emplacement of Cretaceous-Tertiary granodioritic intrusions, are responsible for the formation of quartz veins and the hydrothermal alteration of wall-rocks. Three main altered zones have been detected in the wall-rocks as far as 150 cm from the quartz veins. The distal zone (up to 50-cm thick) contains quartz, chlorite and illite. The intermediate zone is the thickest (up to 80 cm) and is marked by quartz, muscovite, sulphides, kaolinite and native elements such as Au and Ag. The proximal zone, which is close to the quartz veins, is rather thin (up to 25 cm) and contains clay minerals, Al-oxides-hydroxides and sulphides. The transition from the distal to the proximal zone is accompanied by the enrichment of SiO2 and the depletion of all other major elements, except for Fe2O3(tot). Precious metals occur in the highest concentrations in the intermediate zone (Au up to 7.6 ppm and Ag up to 11 ppm). We suggest that gold was transported as a reduced sulphur complex and was precipitated from the hydrothermal solution by the reaction of the sulphur complexes with Fe2+ from the alteration of the mafic minerals of the host-rock. Fluid-wall-rock interactions seem to be the main cause of gold mineralization. Genetic relationships with a strike-slip fault system, hydrothermal alteration zones within the metamorphic wall-rocks, and an entire set of geochemical anomalies are consistent with orogenic-type gold deposits of the epizonal class.

Some Key Features and Possible Origin of the Metamorphic Rock-Hosted Gold Mineralization in Buru Island, Indonesia

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Arifudin Idrus

2014-07-01

Full Text Available DOI: 10.17014/ijog.v1i1.172This paper discusses characteristics of some key features of the primary Buru gold deposit as a tool for a better understanding of the deposit genesis. Currently, about 105,000 artisanal and small-scale gold miners (ASGM are operating in two main localities, i.e. Gogorea and Gunung Botak by digging pits/shafts following gold-bearing quartz vein orientation. The gold extraction uses mercury (amalgamation and cyanide processing. The field study identifies two types/generations of quartz veins namely (1 Early quartz veins which are segmented, sigmoidal, dis­continous, and parallel to the foliation of host rock. The quartz vein is lack of sulfides, weak mineralized, crystalline, relatively clear, and maybe poor in gold, and (2 Quartz veins occurred within a ‘mineralized zone’ of about 100 m in width and ~1,000 m in length. The gold mineralization is strongly overprinted by an argillic alteration zone. The mineralization-alteration zone is probably parallel to the mica schist foliation and strongly controlled by N-S or NE-SW-trending structures. The gold-bearing quartz veins are characterized by banded texture particularly colloform following host rock foliation and sulphide banding, brecciated, and rare bladed-like texture. The alteration types consist of propylitic (chlorite, calcite, sericite, argillic, and carbonation represented by graphite banding and carbon flakes. The ore mineralization is characterized by pyrite, native gold, pyrrhotite, and arsenopyrite. Cinnabar, stibnite, chalcopyrite, galena, and sphalerite are rare or maybe absent. In general, sulphide minerals are rare (<3%. Fifteen rock samples were collected in Wamsaid area for geochemical assaying for Au, Ag, As, Sb, Hg, Cu, Pb, and Zn. Eleven of fifteen samples yielded more than 1.00 g/t Au, in which six of them are in excess of 3.00 g/t Au. It can be noted that all high-grade samples are originally or containing limonitic materials, that suggest

The Metamorphic Rocks-Hosted Gold Mineralization At Rumbia Mountains Prospect Area In The Southeastern Arm of Sulawesi Island, Indonesia

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Hasria Hasria

2017-09-01

Full Text Available Recently, in Indonesia gold exploration activities  are not only focused along volcanic-magmatic belts, but also starting to shift along metamorphic and sedimentary terrains. The study area is located in Rumbia mountains, Bombana Regency, Southeast Sulawesi Province. This paper is aimed to describe characteristics of alteration and ore mineralization associated  with metamorphic rock-related gold deposits.  The study area is found the placer and  primary gold hosted by metamorphic rocks. The gold is evidently derived from gold-bearing quartz veins hosted by Pompangeo Metamorphic Complex (PMC. These quartz veins are currently recognized in metamorphic rocks at Rumbia Mountains. The quartz veins are mostly sheared/deformed, brecciated, irregular vein, segmented and  relatively massive and crystalline texture with thickness from 1 cm to 15.7 cm. The wallrock are generally weakly altered. Hydrothermal alteration types include sericitization, argillic, inner propylitic, propylitic, carbonization and carbonatization. There some precious metal identified consist of native gold and ore mineralization including pyrite (FeS2, chalcopyrite (CuFeS2, hematite (Fe2O3, cinnabar (HgS, stibnite (Sb2S3 and goethite (FeHO2. The veins contain erratic gold in various grades from below detection limit <0.0002 ppm to 18.4 ppm. Based on those characteristics, it obviously indicates that the primary gold deposit present in the study area is of orogenic gold deposit type. The orogenic gold deposit is one of the new targets for exploration in Indonesia

Genesis of the Abu Marawat gold deposit, central Eastern Desert of Egypt

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Zoheir, Basem A.; Akawy, Ahmed

2010-06-01

Gold mineralisation at the Abu Marawat mine, central Eastern Desert of Egypt, is related to a system of massive and sheared, milky quartz veins cutting a sequence of Neoproterozoic island arc metavolcanic/volcaniclastic rocks and related banded iron formation (BIF). Sulphide-bearing quartz veins and related hydrothermal breccia bodies display a range of textures including sheared, boudinaged and recrystallised quartz, open space filling and microbreccia. These variable textures imply a complex history of crack-seal mechanism characterising the relation between mineral deposition and a major N-S-trending shear zone, during a late brittle-ductile deformation event which affected the area at about 550 Ma. Gold-base metal mineralisation is associated with brecciation and fracturing of the iron ore bands, close to silicified shears and related quartz veins. The auriferous quartz lodes are characterised by the occurrence of visible pyrite-chalcopyrite ± pyrrhotite ± sphalerite ± galena mineralisation. Gold is refractory in pyrite and chalcopyrite, but rare visible gold/electrum and telluride specks were observed in a few samples. Hydrothermal alteration includes pervasive silicification, pyritisation, sericitisation, carbonatisation confined to a delicate set of veins and altered shears, and a more widespread propylitic alteration assemblage (quartz + chlorite + pyrite + calcite ± epidote). Fluid inclusion petrography and microthermometric studies suggest heterogeneous trapping of a low-salinity (1.4-6.7 wt.% eq. NaCl) aqueous solution and a carbonic fluid. Evidence for fluid immiscibility during ore formation includes variable liquid/vapour ratios in inclusions along individual trails and bulk inclusion homogenisation into liquid and occasionally to vapour at comparable temperatures. The trapping conditions of intragranular aqueous-carbonic inclusions approximate 264-378 °C at 700-1300 bar. Similar temperature estimates have been obtained from Al

Late-Hercynian intrusion-related gold deposits: An integrated model on the Tighza polymetallic district, central Morocco

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Éric, Marcoux; Khadija, Nerci; Yannick, Branquet; Claire, Ramboz; Gilles, Ruffet; Jean-Jacques, Peucat; Ross, Stevenson; Michel, Jébrak

2015-07-01

Gold have been recently recognized in the Tighza (formerly Jebel Aouam) district, in the Hercynian belt of central Morocco. This district has long been known for its W mineralization, as well as major Pb-Ag-Zn, and minor Sb-Ba deposits, all geographically associated with late-Hercynian calc-alkaline magmatism. Gold mineralization in the district is mainly hosted by thick W-Au quartz veins located around the "Mine granite" small granitic plug. Within the veins, gold grade is highest (up to 70 g/t) close to the granite but rapidly decreases going outward from the granite, defining a perigranitic zoning. Anomalous gold grades have also been measured in hydrothermal skarn layers close to two other granitic plugs (Kaolin granite and Mispickel granite), associated with disseminated As-Fe sulfides. The paragenetic sequence for the W-Au quartz veins shows three stages: (1) an early oxidized stage with wolframite-scheelite associated with early quartz (Q1), (2) an intermediate Bi-As-Te-Mo-Au sulfide stage with loellingite, bismuth minerals and native gold with a later quartz (Q2), restricted to a narrow distance from the granite, and (3) a late lower temperature As-Cu-Zn-(Pb) stage with abundant massive pyrrhotite, arsenopyrite and sphalerite, locally forming independent veins ("pyrrhotite vein"). Both Q1 hyaline and Q2 saccharoidal gold-bearing quartz display aqua-carbonic fluids with minor H2S and Cu and an homogeneous composition (81 mole% H2O, 18 mole% CO2 and about 1 mole% NaCl). The trapping pressure is estimated to 1.5-2 kbar with temperature ranging from 300 to 350 °C. Q1 inclusions have exploded indicating an uplift of the Tighza block, that lead to saccharoidal Q2 quartz deposition with multiphase NaCl-saturated fluid inclusions. 40Ar/39Ar dating demonstrates that the "Mine granite", tungsten skarnoid, scheelite-molybdenite veins, and very likely gold-bearing veins are coeval, emplaced at 286 ± 1 Ma. Multiple and widespread metal sources are indicated by

Relantionships between gold mineralization and granite - Discussion with the support of a pluridisciplinary study of the Passa Tres gold deposit (South Brazil)

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Dressel, Bárbara; Chauvet, Alain; Trzaskos, Barbara; Biondi, Joao Carlos; Bruguier, Olivier; Monie, Patrick; Villanova, Sandro; Bazille, Jose

2016-04-01

The Passa Três Granite, located at East of the Paraná State is elongated following a NNE-SSW direction. This sienogranite is emplaced within metapelites of the meso to neoproterozoic Açungui Group, between the Morro Agudo and Lancinha transcurrent faults, comprising the N040°E trending Lancinha Transcurrent Fault System. Gold mineralization within the Passa Três Granite is constituted by huge quartz veins with sulfides, variable quantities of fluorite and carbonates, forming orebodies with different internal textures, including massive, banded, sheared and brecciated. Structural data indicate the existence of two major fault systems, one N-S and the other E-W, with dips of 15-45°W and 20-75°S, respectively. Both NS and EW systems are interpreted to be contemporaneous and conjugate. Normal motions are everywhere suspected and main mineralized veins are located at opening sites at these fault systems, such as pull-aparts. The structural model suggests that the normal motion can be initiated by shearing along a "guide" level, in which sulfides and clay minerals are concentrated. This configuration can be observed at several scales, such as field, hand samples and thin section. Mineralized veins mainly contain, in addition to the quartz of the gangue, sulphides (pyrite, chalcopyrite, galena, molybdenite), fluorite, chlorite, muscovite, sericite, and carbonate. The presence of sericite, kaolinite and chlorite indicate the occurrence of, at least, propylitic and phyllic-type alterations, both in core of the granite and best-expressed at the rim of quartz-rich orebodies. Gold occurs as native grains in core of the quartz veins, within fractures that affect pyrite and frequently exhibiting normal motions consistent with the one observed at larger scale and systematically associated with chalcopyrite and galena. Quartz veins are sometimes bordered by aplitic dike. Additionally, some of the veins can exhibit a very thin margin of adularia minerals that seems to

Mineralogy of Copper-Gold Deposit, Masjid Daghi Area, Jolfa, IRAN

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Zenoozi, Roya

2010-05-01

The Copper-Gold deposit of Masjid Daghi area is located in the Jolfa quadrangle (scale 1:100,000), East Azerbaijan Province, north-west Iran. The deposit, hosting by sub-volcanic bodies comprise of quartz monzonite composition whose intruded the Tertiary volcanic and volcanic-sedimentary rocks and turbidities. The Tertiary volcanic rocks consist of andesite, trachy andesite and quartz andesite. These mineral-bearing bodies related to Late Eocene sub-volcanic activities which intrudded the Eocene volcanic rocks. Mineralography, XRD and SEM studies showed that the variations in mineralization of the area. The main agent of mineralization is the intrusion of Late Eocene sub volcanic bodies inside the Tertiary volcanic units. The mineralography studies revealed two main groups of mineralization as oxides and sulfides. The sulfide minerals formed as veins, vein lets and stock work.The economic minerals comprise of native gold, copper sulfides. The native gold occurring in siliceous veins and almost as inclusions inside the sulfides minerals such as chalcopyrite. The copper sulfides, contain pyrite, chalcopyrite and chalco-pyrrhoyite. Pyrite is main sulfide in the area and formed as disseminations, cavity filling and colloform. The amount of pyrite, chalcopyrite and chalco-pyrrhoyite increases with depth. Supergene alteration produced digenite, covellite, bornite, and malachite. The alteration occurred as potassic, phyllic, argillic and propylitic minerals. Furthermore, selective sercitic, sericitic-chloritic and alunitic alterations are seen around the mineralized veins. The mineralography studies indicate that pyrite is main mineral phase and native gold occurred in silicious vein almost as inclusions inside the sulfide mineral. Most of economic mineral formed as veins, vein lets, disseminated, cavity filling and colloform which related to intrusions of Late Eocene quartz monzonite bodies into the Eocene volcanic rocks and turbiditse. Some types of alterations such as

Geology, geochemistry and fluid inclusion of Qarachilar Cu-Mo-Au quartz veins, northeast of Kharvana, East Azerbaijan

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Fariba Asiay Soufiani

2018-04-01

ICP-MS for trace elements and REE at the Zarazma Co., Tehran, Iran. Microthermometric data were performed on primary fluid inclusions using the Linkam THMS600 heating–freezing stage at the Iranian Mineral Processing Research Center (IMPRC, Tehran, Iran. Results The rock units exposed in the Qarachilar area are different sets of magmatic phases of QDB including granodiorite-quartz monzodiorite, porphyritic granite, quartz monzonite and acidic-intermediate dikes. Granodiorite-quartz monzodiorite is the dominant phase which hosts the Qarachilar quartz-sulfide veins. Mineralization at Qarachilar occurs as three quartz-sulfide veins. The veins reach up to 700-m in length and average 1-m in width, reaching a maximum of 2-m. They are generally steeply-dipping to the NE at 80°. The reported grades of Mo, Cu and Au range from 20 ppm to 3.6 wt%, 0.7 wt% to 5 wt%, and 0.23 to 37.2 g/t, respectively. Four stages of mineralization can be distinguished at Qarachilar. Stage-1 is represented by quartz veins (ranging from centimeters up to ≤1-m width that contain variable amounts of chalcopyrite and pyrite. Stage-2 is marked by Tm-h and type-2 (Tm-h>Th inclusions are homogenized in the range of 197-530°C and 203-375°C, respectively. They have a calculated bulk salinity of 29.5 to 55.1 and 32.4 to 45.6 wt% NaCl equiv., respectively. The variations in salinity and Th could be explained by a combination of mixing and boiling hydrothermal fluids. These processes led to the deposition of Cu, Mo and Au in the veins. Geology, ore mineralogy, textures, geochemistry and microthermometric data of Qarachilar occurrence are comparable with vein-type Cu-Mo-Au mineralization related to Cu-Mo porphyry and intrusion related gold deposits. References Jamali, H., Dilek, Y., Daliran, F., Yaghubpour, A.M. and Mehrabi, B., 2010. Metallogeny and tectonic evolution of the Cenozoic Ahar-Arasbaran volcanic belt, northern Iran. International Geology Review, 52(4–6: 608–630. Jamali, H. and Mehrabi, B

Oxygen isotope thermometry of quartz-Al2SiO5veins in high-grade metamorphic rocks on Naxos island (Greece)

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Putlitz, Benita; Valley, John; Matthews, Alan; Katzir, Yaron

2002-04-01

Diffusion models predict that peak metamorphic temperatures are best recorded by the oxygen isotope fractionation between minerals in a bi-mineralic rock in which a refractory accessory mineral with slow oxygen diffusion rate is modally minor to a mineral with a faster diffusion rate. This premise is demonstrated for high-grade metamorphism on the island of Naxos, Greece, where quartz-kyanite oxygen isotope thermometry from veins in high-grade metamorphic pelites gives temperatures of 635-690 °C. These temperatures are in excellent agreement with independent thermometry for the regional M2 peak metamorphic conditions and show that the vein minerals isotopically equilibrated at the peak of metamorphism. Quartz-sillimanite fractionations in the same veins give similar temperatures (680+/-35 °C) and suggest that the veins grew near to the kyanite-sillimanite boundary, corresponding to pressures of 6.5 to 7.5 kbar for temperatures of 635-685 °C. By contrast, quartz-kyanite and quartz-biotite pairs in the host rocks yield lower temperature estimates than the veins (590-600 and 350-550 °C, respectively). These lower apparent temperatures are also predicted from calculations of diffusional resetting in the polyphase host-rock system. The data demonstrate that bimineralic vein assemblages can be used as accurate thermometers in high-temperature rocks whereas retrograde exchange remains a major problem in many polymineralic rocks.

Geology of epithermal silver-gold bulk-mining targets, bodie district, Mono County, California

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Hollister, V.F.; Silberman, M.L.

1995-01-01

The Bodie mining district in Mono County, California, is zoned with a core polymetallic-quartz vein system and silver- and gold-bearing quartz-adularia veins north and south of the core. The veins formed as a result of repeated normal faulting during doming shortly after extrusion of felsic flows and tuffs, and the magmatic-hydrothermal event seems to span at least 2 Ma. Epithermal mineralization accompanied repeated movement of the normal faults, resulting in vein development in the planes of the faults. The veins occur in a very large area of argillic alteration. Individual mineralized structures commonly formed new fracture planes during separate fault movements, with resulting broad zones of veinlets growing in the walls of the major vein-faults. The veinlet swarms have been found to constitute a target estimated at 75,000,000 tons, averaging 0.037 ounce gold per ton. The target is amenable to bulkmining exploitation. The epithermal mineralogy is simple, with electrum being the most important precious metal mineral. The host veins are typical low-sulfide banded epithermal quartz and adularia structures that filled voids created by the faulting. Historical data show that beneficiation of the simple vein mineralogy is very efficient. ?? 1995 Oxford University Press.

Noble Gases in Alpine Gold: U/Th-He Dating and Excesses of Radiogenic He and AR

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Eugster, O.; Hofmann, B.; Krahenbuhl, U.; Neuenschwander, J.

1992-07-01

Gold precipitates in hydrothermal fluids along with other heavy elements, such as Ag and Pt. In order to explore the possibility of dating the formation of gold we determined the concentrations of U, Th, and their decay product ^4He, as well as the K and ^40Ar concentrations in vein-type gold and in placer gold samples. The gold-quartz veins at Brusson in the south-western alps were formed approximately 32 Ma ago during an episode of tectonic uplift (Diamond, 1990). Alpine material was deposited as sediment layers in the region of central Switzerland and placer gold is thus relatively abundant in the rivers of the Napf area. We washed placer gold from the river Grosse Fontanne in 1990 and 1991. Placer gold that had been collected from the river Kruempelgraben in 1933 and a sample of vein-type free gold grown on quartz rock from the Brusson area (Val d'Ayas) have been obtained from the Museum of Natural History in Bern. Table 1 gives the results. Most of the ^4He is released above 1050 degrees C, that is when gold melts, indicating that gold is extremely well retentive for He. From the ^4He concentration of (269 +- 20) x 10^-8 cm^3 STP/g, (0.4 +- 0.1) ppm U, and (0.9 +- 0.3) ppm Th for vein-type gold we calculate a U/Th-He age of (36 +- 8)Ma. This age agrees within errors with the proposed age of 32 Ma. The data given in Table 1 show that all placer gold samples contain excesses of radiogenic ^4He and ^40Ar relative to the concentrations expected from the U/Th and K decay, respectively, if we assume a formation age of 32 Ma. The quartz sample is depleted in ^4He but strongly enriched in radiogenic ^40Ar. The excess of ^40Ar(sub)rad is easier to explain than that of ^4He. Vein-type gold and placer gold contain quartz inclusions (Schmid, 1973). The high ^40Ar(sub)rad content of quartz (Table 1) indicates that the ^40Ar(sub)rad excess of gold originates from quartz inclusions. Excess ^4He in gold must be of radiogenic origin. Taking ^20Ne and ^36Ar as a measure for the

Genesis and gold (Copper) Potential in Darestan-Baghu mining area (South of Damghan)

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Tajeddin, H. A.; Rashid Nezhad Omran, N.; Babakhani, A. R.

2000-01-01

Darestan-Baghu gold mining area is exposed at about 100 km south of Damghan. The area is a part of Torud-Chahshirin volcano-plutonic belt that crops out as a ho rst with a N E-S W trend in the northern limit Dasht-e-Kavir. The outcrops in the area are Middle-Eocene volcano-pyroclastics with andesite to da cite in composition, which are intruded by a number of intrusive s including granite to granodiorite bodies. Mineralization in Darestan gold occurrence consists of a copper (gold)-bearing silicic vein with 400 meter length occurring within a N-S trending normal fault in andesitic to dacitic- andesitic massive breccia tuff associated with silicic, argillic and propylitic alterations. Mineralization in the vein includes quartz, chalcopyrite, pyrite, gold, specularite, malachite, and iron-hydroxides. Gold mineralization in Baghu vein (at about 3 km N E of Darestan gold occurrence) is as a silicic vein with 700 meter length occurring within a granodiorite-granite sub volcanic with argillic alteration. Mineralization in Baghu vein consists of quartz, pyrite, chalcopyrite, gold, iron oxides and iron-hydroxides, malachite, chalcocite, covellite and tourmaline. Field observations indicate that considerable contents of gold in Darestan area mainly related to sulfide-bearing silicic veins are intruded within N-S normal faults that are generally associated with hydrothermal alteration of argillic, silicic and chloritic (± epi dote) zones. investigation on other mineralized zones of Darestan and Baghu areas suggests a clear genetic relationship between Darestan copper (gold) occurrence and gold-bearing silicic vein of Baghu. Field observations and laboratory studies show a close relationship between the copper (gold) mineralization and late-stage silicic solutions induced from sub volcanic intrusive s with acidic to intermediate composition in Darestan and Baghu districts. Some of the most important lines of evidence are spatial relationship between ore-bearing silicic veins

Alteration zones: are they a good target for gold deposits in Egypt

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Botros, N.S.

2002-01-01

Extensive rock alterations are a clearly visible characteristic of most Egyptian gold deposits and occurrences. The alterations occur either surrounding the auriferous quartz veins and/or structurally controlled by specific structural features, such as fractures and shear surfaces. Some samples of these alteration zones have proved to be anomalously enriched in gold while others are completely barren. Accordingly there is a controversy on the merit of alteration zones as good lead to gold. Here, the various types of wall rocks wall-rock alteration are reviewed with a discussion on the possible reaction that could have generated them. It is concluded that two main styles of alterations could be recognized in the field. The first results during the liberation of gold from the source rocks, and is characterized by being widely distributed and spatial relation to major structures. The second style, however, is related to the deposition of gold and is recognizable only within a few meters of the auriferous quartz veins. The potentiality of each style is discussed and applications of concept are offered. In general, alterations accompanying the liberation of gold are not completely devoid of gold, but may still retain some gold depending on the mineralogical siting of gold in the source rocks. Moreover, this type of alteration is a good criterion for the presence of gold in the nearby sites. Alterations accompanying deposition of gold, on the other hand, constitute a good target for gold particularly the portions that are dissected by minor quartz veins, veinlets and stockworks (silicification) where gold is believed to migrate to such sites with silica liberated during the different types of alterations. The presence of some efficient precipitants, such as sulphides, carbonates, clay minerals, sericites, iron oxides, chlorite and graphite in the alteration zones is a good indicator of the alteration zone. (author)

Application of geophysical methods to gold prospecting in Minas de Corrales, Uruguay

International Nuclear Information System (INIS)

Costa, Antonio Flavio U.; Dias, Rogerio Aguirre; Barcelos, Andre B.B. de

1993-01-01

Geophysical methods were tested in San Gregorio gold mine, Minas de Corrales, north region of Uruguay. The ores are mainly stockworks, sheeted veinlet zones, ore shoot and disseminated sulfides types, situated in a silicated and carbonated shear zone structure, over granitic mylonites, quartz diorites, quartz-feldspathic breccia, basic rocks and quartz veins. Magnetic and radiometric methods were applied . VLF and EM34-3 detected the high resistivity silicated and carbonated zone and IP detected a weak PFE anomaly associated with pyrite/gold zone. (author)

Geology and geochemistry of epithermal precious metal vein systems in the intra-oceanic arcs of Palau and Yap, western Pacific

Science.gov (United States)

Rytuba, J.J.; Miller, W.R.

1990-01-01

The Palau and Yap arcs are part of an intra-oceanic island-arc-trench system which separates the Pacific and Philippine plates in the western Pacific Ocean. The 350-km-long Palau arc consists of over 200 islands while the 400-km-long Yap arc located to the north has only four major islands exposed. Four of the largest islands in Palau are composed primarily of early Eocene to mid-Miocene volcanic rocks and the four islands comprising Yap contain only Miocene volcanic rocks. Basalt and basaltic andesites of the Babelthuap Formation are the oldest volcanic rocks in Palau and are characterized by high MgO, Ni and Cr and low TiO2 and have a boninitic affinity. They form the central and southeastern parts of Babelthuap Island. Oligocene arc tholeiite flows having an age of 34-35.5 Ma comprise most of the three smaller volcanic islands in Palau and the western part of Babelthuap. The youngest volcanic rocks are dacitic intrusions having an age of 22.7-23.2 Ma. The Yap arc is unusual in that metamorphic rocks up to amphibolite grade form most of the islands. These are underlain by a melange composed of igneous and volcanic clasts as well as clasts from a dismembered copper-gold skarn deposit. Miocene volcanic rocks consisting of flows and volcaniclastic deposits overlie the melange and metamorphic complex. An epithermal precious-metal vein system hosted by flows and flow breccias of the Babelthuap Formation occurs in an area 1.5 km by 1 km on the southeast side of Babelthuap Island. Over 50 veins and mineralized breccias ranging up to 2 m in width and having a strike length up to 500 m contain from trace to 13.0 ppm gold. The veins consist of quartz with varying amounts of sulfides and iron oxides after sulfides and the mineralized breccias consist of brecciated country rock cemented by quartz and iron oxides after sulfides. The veins and mineralized breccias generally dip within 15?? of vertical and have two preferred orientations, north-northwest and north

First evidence of epithermal gold occurrences in the SE Afar Rift, Republic of Djibouti

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Moussa, N.; Fouquet, Y.; Le Gall, B.; Caminiti, A. M.; Rolet, J.; Bohn, M.; Etoubleau, J.; Delacourt, C.; Jalludin, M.

2012-06-01

The geology of the Republic of Djibouti, in the SE Afar Triangle, is characterized by intense tectonic and bimodal volcanic activity that began as early as 25-30 Ma. Each magmatic event was accompanied by hydrothermal activity. Mineralization generally occurs as gold-silver bearing chalcedony veins and is associated with felsic volcanism. Eighty samples from mineralized hydrothermal chalcedony, quartz ± carbonate veins and breccias were studied from ten sites representing four major volcanic events that range in age from early Miocene to the present. The most recent veins are controlled by fractures at the edges of grabens established during the last 4 Myr. Gold in excess of 200 ppb is present in 30% of the samples, with values up to 16 ppm. Mineralogical compositions allowed us to identify different types of mineralization corresponding to different depths in the hydrothermal system: (1) surface and subsurface mineralization characterized by carbonate chimneys, gypsum, silica cap and quartz ± carbonate veins that are depleted in metals and Au; (2) shallow banded chalcedony ± adularia veins related to boiling that contain up to 16 ppm Au, occurring as native gold and electrum with pyrite, and tetradymite; (3) quartz veins with sulfides, and (4) epidote alteration in the deepest hydrothermal zones. Samples in which pyrite is enriched in As tend to have a high Au content. The association with bimodal volcanism, the occurrence of adularia and the native Au and electrum in banded chalcedony veins are typical of epithermal systems and confirm that this type of mineralization can occur in a young intracontinental rift system.

Full paleostress tensor reconstruction using quartz veins of Panasqueira Mine, central Portugal; part I: Paleopressure determination

Science.gov (United States)

Jaques, Luís; Pascal, Christophe

2017-09-01

Paleostress tensor restoration methods are traditionally limited to reconstructing geometrical parameters and are unable to resolve stress magnitudes. Based on previous studies we further developed a methodology to restore full paleostress tensors. We concentrated on inversion of Mode I fractures and acquired data in Panasqueira Mine, Portugal, where optimal exposures of mineralized quartz veins can be found. To carry out full paleostress restoration we needed to determine (1) pore (paleo)pressure and (2) vein attitudes. The present contribution focuses specifically on the determination of pore pressure. To these aims we conducted an extensive fluid inclusion study to derive fluid isochores from the quartz of the studied veins. To constrain P-T conditions, we combined these isochores with crystallisation temperatures derived from geochemical analyses of coeval arsenopyrite. We also applied the sphalerite geobarometer and considered two other independent pressure indicators. Our results point to pore pressures of ∼300 MPa and formation depths of ∼10 km. Such formation depths are in good agreement with the regional geological evolution. The obtained pore pressure will be merged with vein inversion results, in order to achieve full paleostress tensor restoration, in a forthcoming companion paper.

Geochemistry of Gold Deposits in Anka Schist Belt, Northwestern ...

African Journals Online (AJOL)

HP USER

ABSTRACT. Gold quartz veins have been identified associated with the rock formations of the Anka Schist Belt forming eight gold deposits that include Kuba I, Kuba II, Doka, Dumi I, Dumi II, Zurzurfa I, Zurzurfa II, Jameson and Kwali. The present study involves the use of major and trace elements to characterize some of the.

THE ROLE OF DYNAMOMETAMORPHISM IN THE FORMATION OF THE MUKODEK GOLD FIELD (NORTH PRIBAIKALIE

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V. A. Vanin

2017-01-01

Full Text Available The Mukodek gold field is discussed as an example proving that dynamometamorphism is a major factor in the formation of gold deposits in the Abchad fault zone. This deposit belongs to the gold‐silver‐ore zones of mylonitization and schistosity. The ore source is related to the original host rocks with an increased geochemical background concentration of Au. Due to dynamometamorphism processes, gold particles are abundant and mostly enlarged. From the primary rocks, the dynamometamorphites inherit a positive correlation between the number of particles and the concentrations of gold. The dynamometamorphic complex of the ore field developed in two stages, as a minimum. At the early stage (321.0±1.9 Ma, the host rocks were mechanochemically deformed and transformed into the gold‐ bearing mineralized dynamometamorphites containing sericite, chlorite, ankerite, albite, and quartz. In the second stage (280±15 Ma, the albite‐dolomite‐quartz ore veins were formed. Such veins have industrial gold contents.

Geochemistry of Gold Deposits in Anka Schist Belt, Northwestern ...

African Journals Online (AJOL)

Gold quartz veins have been identified associated with the rock formations of the Anka Schist Belt forming eight gold deposits that include Kuba I, Kuba II, Doka, Dumi I, Dumi II, Zurzurfa I, Zurzurfa II, Jameson and Kwali. The present study involves the use of major and trace elements to characterize some of the features that ...

Gold placer and Quaternary stratigraphy of the Jabal Mokhyat area, southern Najd Province, Kingdom of Saudi Arabia

Science.gov (United States)

Schmidt, D.L.; Puffett, W.P.; Campbell, W.L.; Al-Koulak, Z. H.

1981-01-01

An ancient gold placer at Jabal Mokhyat (lat 20?12.2'N., long 43?28'E.), about 90 km east of Qalat Bishah in the southern Najd Province, Kingdom of Saudi Arabia, was studied in 1973. Seven hundred and twenty-eight samples in 25 measured sections were collected along trenches and pits 2.5 m in depth and 2,600 m in total length. Alluvium was thicker than the excavation depth along about 50 percent of the trench length. The average gold content was 4.4 mg per m3, and the highest grade trench contained 40 mg gold per m 3. Because fine particulate gold is rare in the alluvium, a few large particles, 1 to 5 mm in diameter, greatly affected the sampling results. The ancient placer diggings are in small headwater wadis distributed over a 30-km 2 area, and the total dug area is about 1.2 km2. The placer produced an estimated 50 kg of gold and was worked about 2,600 + 250 years ago. The potential for a present-day placer operation is small. The gold is sparsely distributed in locally derived, flood-deposited, immature gravels throughout a stratigraphic section that consists of 1) calichified, saprolitic bedrock of Precambrian age; 2) basal, intensely calichified, saprolitic gravel (0-3 m thick) of Pleistocene age; 3) disconformable, slightly consolidated gravel and sand (0-1 m thick) of late Pleistocene age containing sparse, disseminated caliche; 4) firm loessic silt (0-1 m thick) of early Holocene age; and 5) loose sand and gravel (0.3-1 m thick) of late Holocene age. The loessic silt accumulated during the Holocene pluvial. The top of the loessic silt unit is dated at about 6,000 years B.P. by using charcoal from hearths of ancient man. Following the Holocene pluvial, the climate became arid, and extreme desiccation resulted in abundant eolian sand that progressively diluted the late Holocene gravels. The remnants of the pre-Holocene stratigraphy suggest similar climatic cycles during the Pleistocene. Abundant, sparsely mineralized, gold-bearing quartz veins (0-1 m wide

Uranium in minerals of gold-bearing formations of the North-Eastern part of the USSR

International Nuclear Information System (INIS)

Zagruzina, I.A.; Pinsky, E.M.

1979-01-01

Uranium concentration in 2190 mineral grains from 23 gold-bearing veins of different age deposits in the North-Eastern part of the USSR have been determined using f-radiography. The deposits studied are referred to two formation types: gold-silver epithermal and gold-quartz mesothermal. Differences in physico-chemical conditions of deposite formation of the above formation types are emphasized by the differences in uranium concentration in the vein minerals: 1.0-1.4 g/tU in the first type and 0.4 g/tU in the second one. Uranium content in minerals of gold-bearing veins as compared to minerals of other deposits is characterized by the lowest concentrations. In all gold-bearing veins hydrooxides of iron and hydromica are the main concentrators of uranium. Hypergene stage plays dominating role in uranium accumulation

Characterization of gold mineralization in Garin Hawal area, Kebbi State, NW Nigeria, using remote sensing

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Talaat M. Ramadan

2010-12-01

Full Text Available Garin Hawal area, Kebbi State, NW Nigeria is part of the Neoproterozoic to Early Phanerozoic terrane separating the west African and Congo Cratons. Three main gold-bearing shear zones were detected in the study area from the processed Landsat ETM+ images and extensive ground investigation. Field and petrographical studies indicate that the Neoproterozoic rocks are represented by a highly folded and faulted belt constituted of hornblende, muscovite and graphite schist. They are intruded by granondiorites and late to post granitic dykes. Extensive alteration zones were identified using high resolution QuickBird image along Garin Hawal shear zone. The alteration zones and associated quartz veins are generally concordant with the main NE–SW regional structural trend and are dipping to the NW. Geochemical studies indicate that the gold content reaches 8 g/t in the alteration zones, while it reaches up to 35 g/t in the quartz veins. Mineralogical studies indicate that the alterations are strongly potassium-enriched. Pyrophyllite, kaolinite, illite, gypsum and quartz also occur. The main ore minerals are gold, chalcopyrite, arsenopyrite, pyrite, galena and iron oxides. This study indicates that the alteration zones and the associated quartz veins in the muscovite schist are promising and need more detailed exploration for Au and Ag mineralization to evaluate their potential.

Geostatistical Approach to Estimating the Gold Ore Characteristics and Gold Reserves: A Case Study Daksa Area, Quang Nam Province, Viet Nam

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Luan Truong, Xuan; Luong Le, Van; Quang Truong, Xuan

2015-04-01

Daksa gold deposit is the biggest gold deposits in Vietnam. The Daksa geological structure complicated, distributed mainly metamorphosed sedimentary NuiVu formation (PR3-?1nv2). The sulfide gold ore bodies distributed in quartz schist, quartz - biotite related to faut and distribution wing anticline. The gold ore bodies form circuits, network circuits, circuits lenses; fill the cup surface layer of the developing northeast - southwest; is the less than or west longitude north - SE. The results show that, Au and accompanying elements (Ag, Pb and Zn) have correlated pretty closely. All of its consistent with the logarithmic distribution standard, in accordance with the law of distribution of content mineral rare. The structure functions have nugget effect and spherical models with show that Au and accompanying elements special variation are changes. Au contents shown local anisotropy, no clearly anisotropy (K=1,17) and weakly anisotropy (K=1,4). Intensity mineralization of the ore bodies are quite high with demand spherical conversion coefficient ranging from 0.49 to 0.75 and from 0.66 to 0.97 (for other body). With nugget effects, ore bodies shown that it is consistent with mineralization in the ore bodies study, ore erasable, micro vein, infilling fractures in quartz vein. All of variogram presents local anisotropy, indicated gold mineralization at study area has least two-mineralization stages, consistent with the analysis of mineralography samples. By the results of the structure function study, the authors present the system optimization for exploration deposit and used to evaluate gold reserves by Ordinary Kriging. High accuracy of Kriging estimation results are expressed in the minimum Kriging variance, by compare the results calculated by some other methods (such as distance inverse weighting method, ..) and specially compare to the results of a some blocks have been exploited. Key words: Geostat and gold deposits VN. Daksa and gold mineralization. Geostat

Some Observations on Gold in the Weathering Profile at Garimpo Porquinho, an Artisanal Mine in the Tapajós Region, Brazilian Amazon

OpenAIRE

Sonia Maria Barros de Oliveira; João Henrique Larizzatti

2006-01-01

At Garimpo Porquinho (Tapajós Province, Brazilian Amazon) gold-bearing quartz veins containing sulfides occur in anarrow zone affected by hydrothermal alteration. The artisanally mined veins are exposed in a saprolite zone extending downat least 9 m to the fresh rock and are covered by a 1 m thick residual soil. Lateral gold dispersion in the saprolite is notnoticeable whereas in the soil gold dispersion has been observed as far as 2 m from the vein. Trace metals associated with goldinclude A...

U-Pb zircon and 40Ar/39Ar geochronology of sericite from hydrothermal alteration zones: new constraints for the timing of Ediacaran gold mineralization in the Sukhaybarat area, western Afif terrane, Saudi Arabia

Science.gov (United States)

Harbi, Hesham M.; Ali, Kamal A.; McNaughton, Neal J.; Andresen, Arild

2018-04-01

The Sukhaybarat East and Red Hill deposits, in the northeastern part of the Arabian Shield, are mesothermal vein-type gold deposits hosted by late Cryogenian-Ediacaran intrusive rocks of the Idah suites (diorite, tonalite, granodiorite) and, at Sukhaybarat East, also by Ediacaran metasedimentary rocks. Gold mineralization comprises quartz-arsenopyrite veins (Sukhaybarat East), quartz-carbonate-pyrite veins (Red Hill), and subordinate gold-base metal sulfide veins. In the Red Hill deposit, alteration is complicated due to multiple overprinting hydrothermal events and is characteristically affected by pervasive, pink quartz-K-feldspar-hematite alteration which is overprinted by potassic alteration characterized by a quartz-biotite-carbonate-muscovite/sericite-rutile-apatite assemblage. This assemblage is associated with molybdenite veins which appear to form late in the paragenetic sequence and may represent either evolution of the ore fluid composition, or a later, unrelated mineralized fluids. Hydrothermal alteration at the Sukhaybarat East deposit is dominated by quartz-carbonate-sericite-arsenopyrite assemblages. Zircon from ore-hosting tonalite at Sukhaybarat East yields a U-Pb age of 629 ± 6 Ma, and biotite from the same rock gives an 40Ar/39Ar age of 622 ± 23 Ma. The 40Ar/39Ar age is within the uncertainty range for the U-Pb age of the host intrusion and is interpreted as a minimally disturbed cooling age for the tonalite. In the Red Hill area, granodiorite was emplaced at 615 ± 5 Ma, whereas muscovite/sericite separated from a mineralized sample of a quartz-carbonate-pyrite vein, that was overprinted by molybdenite-bearing veinlets, yields an 40Ar/39Ar age of 597 ± 8 Ma. We interpreted this age to represent the maximum age of the molybdenite mineralization and the probable minimum age of gold mineralization in the Red Hill deposit.

Structural control on the emplacement of contemporaneous Sn-Ta-Nb mineralized LCT pegmatites and Sn bearing quartz veins: Insights from the Musha and Ntunga deposits of the Karagwe-Ankole Belt, Rwanda

Science.gov (United States)

Hulsbosch, Niels; Van Daele, Johanna; Reinders, Nathan; Dewaele, Stijn; Jacques, Dominique; Muchez, Philippe

2017-10-01

The Nb-Ta-Sn pegmatites and Sn quartz veins of the Rwamagana-Musha-Ntunga area in eastern Rwanda are part of the Mesoproterozoic Karagwe-Ankole Belt. These commodities are on a regional scale spatiotemporally associated to the early Neoproterozoic fertile G4-granite generation. Although a transition from the lithium-cesium-tantalum pegmatites to cassiterite-microcline-quartz veins has been observed in the Rwamagana-Musha-Ntunga area, the structural control and the paragenetic relationship between the mineralized pegmatites and the Sn bearing quartz veins is largely unknown. Consequently, this study investigates the occurrence of pegmatites and quartz veins and the structural and lithological controls on their emplacement. The metasediments in the area are affected by a regional compressional regime with a shortening direction oriented N70E, which resulted in a N20W-oriented fold sequence. The Lake Muhazi granite is present in center of the Karehe anticline. The structural orientations of pegmatites and quartz veins show that two important factors control their emplacement. The first control is the reactivation of pre-existing discontinuities such as the bedding, bedding-parallel joints or strike-slip fault planes. In view of the regional structural grain in the Rwamagana-Musha-Ntunga area, this corresponds with abundant N20W-oriented pegmatites and quartz veins. The reactivation is strongly related to the lithology of the host rocks. The Musha Formation, which mainly consists of decimeter- to meter-scale lithological alternations of metapelite, metasiltstone and metasandstone, represents the most suitable environment for bedding reactivation. This is reflected in the predominance of bedding-parallel pegmatites and quartz veins hosted by the Musha Formation. Strike-parallel joints were mainly observed in the competent lithologies. The second controlling factor is related to the regional post-compressional stress regime. New joints initiated upon emplacement of the

Mechanisms of fine extinction band development in vein quartz: new insights from correlative light and electron microscopy

Science.gov (United States)

Derez, Tine; Van Der Donck, Tom; Plümper, Oliver; Muchez, Philippe; Pennock, Gill; Drury, Martyn R.; Sintubin, Manuel

2017-07-01

Fine extinction bands (FEBs) (also known as deformation lamellae) visible with polarized light microscopy in quartz consist of a range of nanostructures, inferring different formation processes. Previous transmission electron microscopy studies have shown that most FEB nanostructures in naturally deformed quartz are elongated subgrains formed by recovery of dislocation slip bands. Here we show that three types of FEB nanostructure occur in naturally deformed vein quartz from the low-grade metamorphic High-Ardenne slate belt (Belgium). Prismatic oriented FEBs are defined by bands of dislocation walls. Dauphiné twin boundaries present along the FEB boundaries probably formed after FEB formation. In an example of two sub-rhombohedral oriented FEBs, developed as two sets in one grain, the finer FEB set consists of elongated subgrains, similar to FEBs described in previous transmission electron microscopy studies. The second wider FEB set consists of bands with different dislocation density and fluid-inclusion content. The wider FEB set is interpreted as bands with different plastic strain associated with the primary growth banding of the vein quartz grain. The nanometre-scale fluid inclusions are interpreted to have formed from structurally bounded hydroxyl groups that moreover facilitated formation of the elongate subgrains. Larger fluid inclusions aligned along FEBs are explained by fluid-inclusion redistribution along dislocation cores. The prismatic FEB nanostructure and the relation between FEBs and growth bands have not been recognized before, although related structures have been reported in experimentally deformed quartz.

Gold volatile species atomization and preconcentration in quartz devices for atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Arslan, Yasin [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Mehmet Akif Ersoy University, Faculty of Arts & Sciences, Chemistry Department, 15030 Burdur (Turkey); Musil, Stanislav; Matoušek, Tomáš; Kratzer, Jan [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Dědina, Jiří, E-mail: dedina@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

2015-01-01

The on-line atomization of gold volatile species was studied and the results were compared with thermodynamic calculations in several quartz atomizers, namely: diffusion flame, flame-in-gas-shield, flame-in-plain-tube, externally heated T-tube and externally heated flame-in-T-tube. Atomization mechanism in the explored devices is proposed, where volatile species are converted to thermodynamically stable AuH at elevated temperature over 500 °C and then atomized by an interaction with a cloud of hydrogen radicals. Because of its inherent simplicity and robustness, diffusion flame was employed as a reference atomizer. It yielded atomization efficiency of 70 to 100% and a very good long time reproducibility of peak area sensitivity: 1.6 to 1.8 s μg{sup −1}. Six and eleven times higher sensitivity, respectively, was provided by atomizers with longer light paths in the observation volume, i.e. externally heated T-tube and externally heated flame-in-T-tube. The latter one, offering limit of detection below 0.01 μg ml{sup −1}, appeared as the most prospective for on-line atomization. Insight into the mechanism of atomization of gold volatile species, into the fate of free atoms and into subsequent analyte transfer allowed to assess possibilities of in-atomizer preconcentration of gold volatile species: it is unfeasible with quartz atomizers but a sapphire tube atomizer could be useful in this respect. - Highlights: • On-line atomization of gold volatile species for AAS in quartz devices was studied. • Atomization mechanism was proposed and atomization efficiency was estimated. • Possibilities of in-atomizer preconcentration of gold volatile species were assessed.

Gold deposits in the western sector of the Central Spanish System

International Nuclear Information System (INIS)

Barrios, S.; Florido, P.; Reguilon, R.

2010-01-01

The gold deposits in the western sector of the Central Spanish System can be grouped in: (1) gold quartz veins type (El Chivote, La Pedrera), (2) paleoplacers: gold nuggets in tertiary alluvial deposits (Las Cavenes, Sierro de Coria), (3) quaternary placers (Rio Erjas), (4) gold nuggets in a regolith developed on the Schist and Graywacke Complex (CEG) (Casillas de Coria). The morphological study of gold nuggets will provide physical, chemical, bacteriological and climatic characteristics. Mining works are located on these deposits from roman time to the present day. (Author)

Application of titanium-in-quartz thermobarometry to greenschist facies veins and recrystallized quartzites in the Hsüehshan range, Taiwan

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S. Kidder

2013-01-01

Full Text Available The accuracy, reliability and best practises of Ti-in-quartz thermobarometry (TitaniQ in greenschist facies rocks have not been established. To address these issues, we measured Ti concentrations in rutile-bearing samples of moderately deformed, partially recrystallized quartzite and vein quartz from the Hsüehshan range, Taiwan. The spread of Ti concentrations of recrystallized grains in quartzite correlates with recrystallized grain size. Recrystallized quartz (grain size ~100–200 μm that formed during early deformation within the biotite stability field shows a marked increase in intermediate Ti-concentration grains (~1–10 ppm relative to detrital porphyroclasts (Ti ~0.1–200 ppm. Fine recrystallized quartz (~5% of the samples by area, grain size ~10–20 μm has a further restricted Ti concentration peaking at 0.8–2 ppm. This trend suggests equilibration of Ti in recrystallized quartz with a matrix phase during deformation and cooling. Unlike previously documented examples, Ti concentration in the quartzite is inversely correlated with blue cathodoluminescence. Deformation was associated with a minimum grain boundary diffusivity of Ti on the order of 10−22m2 s−1. Vein emplacement and quartzite recrystallization are independently shown to have occurred at 250–350 °C and 300–410 °C, respectively, with lithostatic pressure of 3–4 kbar (assuming a geothermal gradient of 25° km−1, and with hydrostatic fluid pressure. Estimates of the accuracy of TitaniQ at these conditions depend on whether lithostatic or fluid pressure is used in the TitaniQ calibration. Using lithostatic pressure and these temperatures, the Thomas et al. (2010 calibration yields Ti concentrations within error of concentrations measured by SIMS. If fluid pressure is instead used, predicted temperatures are ~30–40 °C too low. TitaniQ has potential to yield accurate PT information for vein emplacement and dynamic recrystallization of quartz at

A Palaeoproterozoic multi-stage hydrothermal alteration system at Nalunaq gold deposit, South Greenland

DEFF Research Database (Denmark)

Bell, Robin-Marie; Kolb, Jochen; Waight, Tod Earle

2017-01-01

Nalunaq is an orogenic, high gold grade deposit situated on the Nanortalik Peninsula, South Greenland. Mineralisation is hosted in shear zone-controlled quartz veins, located in fine- and medium-grained amphibolite. The deposit was the site of Greenland’s only operating metalliferous mine until i...

Source of boron in the Palokas gold deposit, northern Finland: evidence from boron isotopes and major element composition of tourmaline

Science.gov (United States)

Ranta, Jukka-Pekka; Hanski, Eero; Cook, Nick; Lahaye, Yann

2017-06-01

The recently discovered Palokas gold deposit is part of the larger Rompas-Rajapalot gold-mineralized system located in the Paleoproterozoic Peräpohja Belt, northern Finland. Tourmaline is an important gangue mineral in the Palokas gold mineralization. It occurs as tourmalinite veins and as tourmaline crystals in sulfide-rich metasomatized gold-bearing rocks. In order to understand the origin of tourmaline in the gold-mineralized rocks, we have investigated the major element chemistry and boron isotope composition of tourmaline from three areas: (1) the Palokas gold mineralization, (2) a pegmatitic tourmaline granite, and (3) the evaporitic Petäjäskoski Formation. Based on textural evidence, tourmaline in gold mineralization is divided into two different types. Type 1 is located within the host rock and is cut by rock-forming anthophyllite crystals. Type 2 occurs in late veins and/or breccia zones consisting of approximately 80% tourmaline and 20% sulfides, commonly adjacent to quartz veins. All the studied tourmaline samples belong to the alkali-group tourmaline and can be classified as dravite and schorl. The δ11B values of the three localities lie in the same range, from 0 to -4‰. Tourmaline from the Au mineralization and from the Petäjäskoski Formation has similar compositional trends. Mg is the major substituent for Al; inferred low Fe3+/Fe2+ ratios and Na values (molybdenite related to the tourmaline-sulfide-quartz veins, we propose that the tourmaline-forming process is a result of a single magmatic-hydrothermal event related to the extensive granite magmatism at around 1.79-1.77 Ga. Tourmaline was crystallized throughout the hydrothermal process, which resulted in the paragenetic variation between type 1 and type 2. The close association of tourmaline and gold suggests that the gold precipitated from the same boron-rich source as tourmaline.

Tectonic setting of synorogenic gold deposits of the Pacific Rim

Science.gov (United States)

Goldfarb, R.J.; Phillips, G.N.; Nokleberg, W.J.

1998-01-01

More than 420 million oz of gold were concentrated in circum-Pacific synorogenic quartz loades mainly during two periods of continental growth, one along the Gondwanan margin in the Palaeozoic and the other in the northern Pacific basin between 170 and 50 Ma. These ores have many features in common and can be grouped into a single type of lode gold deposit widespread throughout clastic sedimentary-rock dominant terranes. The auriferous veins contain only a few percent sulphide minerals, have gold:silver ratios typically greater than 1:1, show a distinct association with medium grade metamorphic rocks, and may be associated with large-scale fault zone. Ore fluids are consistently of low salinity and are CO2-rich. In the early and middle Palaeozoic in the southern Pacific basin, a single immense turbidite sequence was added to the eastern margin of Gondwanaland. Deformation of these rocks in southeastern Australia was accompanied by deposition of at least 80 million oz of gold in the Victorian sector of the Lachlan fold belt mainly during the Middle and Late Devonian. Lesser Devonian gold accumulations characterized the more northerly parts of the Gondwanan margin within the Hodgkinson-Broken River and Thomson fold belts. Additional lodes were emplaced in this flyschoid sequence in Devonian or earlier Palaeozoic times in what is now the Buller Terrane, Westland, New Zealand. Minor post-Devonian growth of Gondwanaland included terrane collision and formation of gold-bearing veins in the Permian in Australia's New England fold belt and in the Jurassic-Early Cretaceous in New Zealand's Otago schists. Collision and accretion of dozens of terranes for a 100-m.y.-long period against the western margin of North America and eastern margin of Eurasia led to widespread, lattest Jurassic to Eocene gold veining in the northern Pacific basin. In the former location, Late Jurassic and Early Cretaceous veins and related placer deposits along the western margin of the Sierra Nevada

Gold clusters sliding on graphite: a possible quartz crystal microbalance experiment?

International Nuclear Information System (INIS)

Pisov, S; Tosatti, E; Tartaglino, U; Vanossi, A

2007-01-01

A large measured two-dimensional (2D) diffusion coefficient of gold nanoclusters on graphite has been known experimentally and theoretically for about a decade. When subjected to a lateral force, these clusters should slide with an amount of friction that can be measured. We examine the hypothetical possibility of measuring by quartz crystal microbalance (QCM) the phononic sliding friction of gold clusters in the size range around 250 atoms on a graphite substrate between 300 and 600 K. Assuming the validity of Einstein's relations of ordinary Brownian motion and making use of the experimentally available activated behaviour of the diffusion coefficients, we can predict the sliding friction and slip times as a function of temperature. It is found that a prototypical deposited gold cluster could yield slip times at the standard measurable size of 10 -9 s for temperatures around 450-500 K, or 200 0 C. Since gold nanoclusters may also melt at around these temperatures, QCM could offer the additional chance of observing this phenomenon through a frictional change

Trace elements and isotope data of the Um Garayat gold deposit, Wadi Allaqi district, Egypt

Science.gov (United States)

Zoheir, Basem; Emam, Ashraf; Pitcairn, Iain K.; Boskabadi, Arman; Lehaye, Yann; Cooper, Matthew J.

2018-04-01

Trace element composition of sulfides and O, C, Sr and S isotopic data are assessed to constrain the evolution and potential fluid and metal sources of the Um Garayat gold deposit. Ore microscopy and BSE investigations of quartz veins show blocky arsenopyrite and pyrite replaced in part by pyrrhotite, chalcopyrite, sphalerite, galena, and gersdorffite. Free-milling gold occurs commonly in close association with the late sulfides, and along fractures in pyrite. On the other hand, recrystallized pyrite is disseminated in host metavolcaniclastic/metasedimentary rocks that commonly contain carbonaceous material. In situ LA-ICP-MS analysis of sulfides shows the recrystallized pyrite enriched in most trace elements, while blocky pyrite contains only some traces of arsenic. Detected concentrations of gold (up to 17 ppm) were only reported in arsenopyrite disseminated in quartz veins. The δ34S values of blocky pyrite and pyrrhotite in quartz veins define a narrow range (1.6 to 3.7‰), suggesting a homogenous sulfur source which is consistent with the dominantly mafic host rocks. The recrystallized pyrite has a distinctive sulfur isotope composition (δ34S - 9.3 to - 10.6‰), which is rather comparable to diagenetic sulfides. Hydrothermal carbonate in quartz veins and wallrock have nearly constant values of δ18O (10.5 to 11.9‰) and δ13C (- 4.2 to - 5.5‰). Based on constraints from mineral assemblages and chlorite thermometry, data of six samples indicate that carbonate precipitation occurred at 280 °C from a homogenous hydrothermal fluid with δ18OH2O 4.4 ± 0.7‰ and δ13C = 3.7 ± 0.8‰. Strontium isotope values of two samples (87Sr/86Sr = 0.7024 and 0.7025) are similar to the initial 87Sr/86Sr ratios of island arc metabasalts ( 710 Ma) in the South Eastern Desert. The generally homogenous sulfur, C, O, Sr isotope data are suggestive of metamorphogenic fluids, likely produced from dominantly mafic volcanic rocks at the greenschist-amphibolite facies transition.

Low rate of asymptomatic cerebral embolism and improved procedural efficiency with the novel pulmonary vein ablation catheter GOLD: results of the PRECISION GOLD trial.

Science.gov (United States)

De Greef, Yves; Dekker, Lukas; Boersma, Lucas; Murray, Stephen; Wieczorek, Marcus; Spitzer, Stefan G; Davidson, Neil; Furniss, Steve; Hocini, Mélèze; Geller, J Christoph; Csanádi, Zoltan

2016-05-01

This prospective, multicentre study (PRECISION GOLD) evaluated the incidence of asymptomatic cerebral embolism (ACE) after pulmonary vein isolation (PVI) using a new gold multi-electrode radiofrequency (RF) ablation catheter, pulmonary vein ablation catheter (PVAC) GOLD. Also, procedural efficiency of PVAC GOLD was compared with ERACE. The ERACE study demonstrated that a low incidence of ACE can be achieved with a platinum multi-electrode RF catheter (PVAC) combined with procedural manoeuvres to reduce emboli. A total of 51 patients with paroxysmal atrial fibrillation (AF) (age 57 ± 9 years, CHA2DS2-VASc score 1.4 ± 1.4) underwent AF ablation with PVAC GOLD. Continuous oral anticoagulation using vitamin K antagonists, submerged catheter introduction, and heparinization (ACT ≥ 350 s prior to ablation) were applied. Cerebral magnetic resonance imaging (MRI) scans were performed within 48 h before and 16-72 h post-ablation. Cognitive function assessed by the Mini-Mental State Exam at baseline and 30 days post-ablation. New post-procedural ACE occurred in only 1 of 48 patients (2.1%) and was not detectable on MRI after 30 days. The average number of RF applications per patient to achieve PVI was lower in PRECISION GOLD (20.3 ± 10.0) than in ERACE (28.8 ± 16.1; P = 0.001). Further, PVAC GOLD ablations resulted in significantly fewer low-power (GOLD in combination with established embolic lowering manoeuvres results in a low incidence of ACE. Pulmonary vein ablation catheter GOLD demonstrates improved biophysical efficiency compared with platinum PVAC. ClinicalTrials.gov NCT01767558. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

Exploration for gold mineralization in the Arabo Nubian Shield: Using remote sensing Approach

Science.gov (United States)

Ramadan, Talaat

2013-04-01

In the southern part of the Eastern Desert of Egypt, Landsat Thematic Mapper (ETM+) data and fieldwork was combined with mineralogical and geochemical investigations in order to detect and characterize alteration zones within Pan-African rocks. The processing of Landsat ETM+ data using ratioing (bands 5/7,5/1,4/3 in Red, Green, Blue) showed two different types of alteration zones (type l and 2). Type 1 is close to the ophiolitic ultramafic rocks and type 2 is located within island-arc related metavolcanic rocks at the study areas. Both of these alteration zones are concordant with the main NW-SE structural trend. Mineralogical studies indicate that the alteration zones of type 1 consist mainly of calcite, ankerite, magnesite, dolomite and quartz. Chromian spinel, pyrite, and Ni-bearing sulphides (gersdorffite, pentlandite and polydymite) are the main ore minerals within this zone. Alteration zones of type 2 are strongly potassium-enriched and pyrophyllite, kaolinite, illite, gypsum and quartz occur. The brecciated quartz-veins associated with theses alteration zones consist of quartz, Fe-hydroxides, hematite and native gold. The gold content reaches up to 5 g/t in the alteration zone, while it extends up to 50 g/t in the quartz veins. This study presents a mineralogical characterization of such zones and demonstrates the utility of orbital remote sensing for finding unknown alteration zones in the Eastern Desert and other arid areas with similar host rock lithologies.

Stable isotope and fluid inclusion signatures of hydrothermal fluids in transcrustal fault zones: significance for orogenic, Archean lode-gold mineralization

International Nuclear Information System (INIS)

Neumayr, P.; Hagemann, S.G.; Groves, D.I.

1999-01-01

Full text: Large to giant (>1t) gold deposits are typically hosted in second- and third-order structures adjacent to largely barren, transcrustal fault zones. Gold-bearing hydrothermal fluids have been channelled within the transcrustal fault zones from mantle and deep crustal sources into the second- and third-order structures, where gold has been deposited. Transcrustal fault zones are long-lived structures with specific deformation events relating to gold deposition in the second- and third-order structures. For example the Archaean Perseverance Fault in the Yilgarn Craton of Western Australia evolved from a wide (5km) ductile shear zone during D2 to a narrow ( 2 -CH 4 -dominated compositions with minor H 2 O and H 2 S components, whereas there are H 2 O-dominated H 2 O-CO 2 +CH 4 fluids with a significant H 2 S component in the second- and third-order shear zones at the Sigma gold deposit, a major gold deposit 5km to the north of the CTZ. These differences can be explained by continuous phase separation, with CO 2 -vapour escape into the upper portions of the ductile uncapped CTZ, contrasting with in-situ phase separation of the gold-bearing fluids in crack-seal veins in the second-order shear zones at Sigma, with trapping of both the episodic vapour and liquid components in individual sealed veins. Gold mineralization in the second- and third-order structures appears to be controlled by the high H 2 S activity of the aqueous hydrothermal fluids. because gold was likely carried in a bisulphide complex and was deposited during sulfidation reactions in the wallrock and phase separation in the quartz vein. In contrast, the carbonic fluids in the CTZ lacked the ability to carry significant metal ligands due to their low H 2 S activity. Oxygen isotopes from hydrothermal quartz within the CTZ (13.3 to 15.6 per mil, av. 14.0 per mil; VSMOW) are heavier than those from mineralized quartz veins in second- and third-order shear zones (11.8 to 19.6 per mil, av. 12.2 per

Gold volatile species atomization and preconcentration in quartz devices for atomic absorption spectrometry

Czech Academy of Sciences Publication Activity Database

Arslan, Y.; Musil, Stanislav; Matoušek, Tomáš; Kratzer, Jan; Dědina, Jiří

103-104, JAN-FEB (2015), s. 155-163 ISSN 0584-8547 R&D Projects: GA ČR GA14-23532S Grant - others:GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : gold * volatile species generation * quartz atomizers * atomic absorption spectrometry Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.289, year: 2015

Granitoid-associated gold mineralization in Egypt: a case study from the Atalla mine

Science.gov (United States)

Zoheir, Basem; Deshesh, Fatma; Broman, Curt; Pitcairn, Iain; El-Metwally, Ahmed; Mashaal, Shabaan

2018-06-01

Gold-bearing sulfide-quartz veins cutting mainly through the Atalla monzogranite intrusion in the Eastern Desert of Egypt are controlled by subparallel NE-trending brittle shear zones. These veins are associated with pervasive sericite-altered, silicified, and ferruginated rocks. The hosting shear zones are presumed as high-order structures of the Najd-style faults in the Central Eastern Desert ( 615-585 Ma). Ore minerals include an early pyrite-arsenopyrite (±pyrrhotite) mineralization, partly replaced by a late pyrite-galena-sphalerite-chalcopyrite (±gold/electrum ± tetrahedrite ± hessite) assemblage. Gold occurs as small inclusions in pyrite and arsenopyrite, or more commonly as intergrowths with galena and sphalerite/tetrahedrite in microfractures. Arsenopyrite geothermometry suggests formation of the early Fe-As-sulfide mineralization at 380-340 °C, while conditions of deposition of the late base metal-gold assemblage are assumed to be below 300 °C. Rare hessite, electrum, and Bi-galena are associated with sphalerite and gold in the late assemblage. The early and late sulfide minerals show consistently a narrow range of δ34S ‰ (3.4-6.5) that overlaps with sulfur isotopic values in ophiolitic rocks. The Au-quartz veins are characterized by abundant CO2 and H2O ± CO2 ± NaCl inclusions, where three-dimensional clusters of inclusions show variable aqueous/carbonic proportions and broad range of total (bimodal) homogenization temperatures. Heterogeneous entrapment of immiscible fluids is interpreted to be caused by unmixing of an originally homogenous, low salinity ( 2 eq. mass % NaCl) aqueous-carbonic fluid, during transition from lithostatic to hydrostatic conditions. Gold deposition occurred generally under mesothermal conditions, i.e., 1.3 kbar and 280 °C, and continued during system cooling to chemistry of the ore fluids.

Composition and genesis of the Konevinsky gold deposit, Eastern Sayan, Russia

Science.gov (United States)

Damdinov, B. B.; Zhmodik, S. M.; Roshchektaev, P. A.; Damdinova, L. B.

2016-03-01

The Konevinsky gold deposit in southeast Eastern Sayan is distinguished from most known deposits in this region (Zun-Kholba, etc.) by the geological setting and composition of mineralization. To elucidate the cause of the peculiar mineralization, we have studied the composition, formation conditions, and origin of this deposit, which is related to the Ordovician granitoid pluton 445-441 Ma in age cut by intermediate and basic dikes spatially associated with metavolcanic rocks of the Devonian-Carboniferous Ilei Sequence. Four mineral assemblages are recognized: (1) quartz-pyrite-molybdenite, (2) quartz-gold-pyrite, (3) gold-polysulfide, and (4) telluride. Certain indications show that the ore was formed as a result of the superposition of two distinct mineral assemblages differing in age. The first stage dated at ~440 Ma is related to intrusions generating Cu-Mo-Au porphyry mineralization and gold-polysulfide veins. The second stage is controlled by dikes pertaining to the Devonian-Carboniferous volcanic-plutonic association. The second stage is characterized by gain of Hg and Te and formation of gold-mercury-telluride paragenesis.

Fault geometry and fluid-rock reaction: Combined controls on mineralization in the Xinli gold deposit, Jiaodong Peninsula, China

Science.gov (United States)

Yang, Lin; Zhao, Rui; Wang, Qingfei; Liu, Xuefei; Carranza, Emmanuel John M.

2018-06-01

The structures and fluid-rock reaction in the Xinli gold deposit, Jiaodong Peninsula, were investigated to further understand their combined controls on the development of permeability associated with ore-forming fluid migration. Orebodies in this deposit are hosted by the moderately SE-to S-dipping Sanshandao-Cangshang fault (SCF). Variations in both dip direction and dip angle along the SCF plane produced fault bends, which controlled the fluid accumulation and ore-shoot formation. Gold mineralizations occurred in early gold-quartz-pyrite and late gold-quartz-polymetallic sulphide stages following pervasive sericitization and silicification alterations. Theoretical calculation indicates that sericitization caused 8-57% volume decrease resulting in the development/enlargement of voids, further increase of grain-scale permeability, and resultant precipitation of the early gold-quartz-pyrite pods, which destroyed permeability. The rock softening produced by alterations promoted activities of SCF secondary faults and formation of new fractures, which rebuilt the permeability and controlled the late gold-quartz-polymetallic sulfide veins. Quantitative studies on permeability distributions show that the southwestern and northeastern bend areas with similar alteration and mineralization have persistent and anti-persistent permeability networks, respectively. These were likely caused by different processes of rebuilding permeability due to different stress states resulting from changes in fault geometry.

Gold in primary high thermal transformations of the Au porphyry deposit Biely vrch

International Nuclear Information System (INIS)

Kozak, J.; Kodera, P.; Lexa, J.; Chovan, M.

2014-01-01

Porphyry gold deposit Biely vrch is situated in northern part of the Javorie stratovolcano in eastern part of Central Slovakia Volcanic Field. Intrusion of diorite to andesite porphyry with andesites is affected by hydrothermal alterations with dominant intermediate argillic alteration. Accumulations of gold are spatially associated with stockwork, formed by different types of quartz veinlets. Gold grains occur in altered rocks in the vicinity of quartz veinlets and rarely also as inclusions in vein. Analysed gold grains are chemically very homogenous and have fineness between 87 to 99.50 wt % Au while silver is the only significant element in addition to gold. In deeper parts of the deposit gold also occurs associated with K and Ca-Na silicate alteration which confirms precipitation of gold already in early stages of the hydrothermal system from high salinity Fe-K rich salt melt based on analyses of corresponding fluid inclusions. Difference in the fineness of gold is not significant between primary and secondary hydrothermal alterations. The highest fineness of gold (more than 99 wt %) in advanced argillic alteration is probably caused by remobilisation by acidic hydrothermal fluids. (authors)

Flotation of beryl from milky white quartz veins of Igla area, eastern desert of egypt

International Nuclear Information System (INIS)

Abdel Monem, H.M.; Aly, M.M.; Abdel Aty, M.A.

1988-01-01

Several milky white quartz veins and lenses occur at the Igla area of the central eastern desert. These veins are beryl-bearing and are introduced into breociated rhyolite and porphyritic dolerites as country rock. An effort has been made to up-grade such a low-grade ore material and therefore a head sample assaying about o.28% Be O was prepared. Flotation technique using sodium alkyl-aryl sulfonate as a collector has proven most satisfactory for separating beryl grains at ph value less than 3.5. indeed, a best recovery exceeding 90% Be O could be obtained by adding an activator of some metal chlorides; viz Fe Cl 3 , and Pb Cl 2 and Ca Cl 2 at various PH value. The study has made possible the elaboration of a proposed flow sheet whereby a beryl concentrate assaying 9.35% Be o was obtained with an overall recovery of about 93%

Mineralogy and fluid inclusion studies in kalchoye Copper- gold deposit, East of Esfahan

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Rezvan Mehvary

2009-09-01

Full Text Available Kalchoye Copper-gold deposit is located about 110 kilometers east of Esfahan province and within the Eocene volcano sedimentary rocks. Sandy tuff and andesite lava are important members of this complex.The form of mineralization in area is vein and veinlet and quartz as the main gangue phase. The main ore minerals are chalcopyrite, chalcocite, galena and weathered minerals such as goethite, iron oxides, malachite and azurite. Studies in area indicate that ore mineralization Kalchoye is low sulfide, quartz type of hydrothermal ore deposits and results of thermometry studies on quartz minerals low- medium fluid with low potential mineralization is responsible for mineralization in this area.

Quartz-pebble-conglomerate gold deposits: Chapter P in Mineral deposit models for resource assessment

Science.gov (United States)

Taylor, Ryan D.; Anderson, Eric D.

2018-05-17

Quartz-pebble-conglomerate gold deposits represent the largest repository of gold on Earth, largely due to the deposits of the Witwatersrand Basin, which account for nearly 40 percent of the total gold produced throughout Earth’s history. This deposit type has had a controversial history in regards to genetic models. However, most researchers conclude that they are paleoplacer deposits that have been modified by metamorphism and hydrothermal fluid flow subsequent to initial sedimentation.The deposits are found exclusively within fault-bounded depositional basins. The periphery of these basins commonly consists of granite-greenstone terranes, classic hosts for lode gold that source the detrital material infilling the basin. The gold reefs are typically located along unconformities or, less commonly, at the top of sedimentary beds. Large quartz pebbles and heavy-mineral concentrates are found associated with the gold. Deposits that formed prior to the Great Oxidation Event (circa 2.4 giga-annum [Ga]) contain pyrite, whereas younger deposits contain iron oxides. Uranium minerals and hydrocarbons are also notable features of some deposits.Much of the gold in these types of deposits forms crystalline features that are the product of local remobilization. However, some gold grains preserve textures that are undoubtedly of detrital origin. Other heavy minerals, such as pyrite, contain growth banding that is truncated along broken margins, which indicates that they were transported into place as opposed to forming by in situ growth in a hydrothermal setting.The ore tailings associated with these deposits commonly contain uranium-rich minerals and sulfides. Oxidation of the sulfides releases sulfuric acid and mobilizes various metals into the environment. The neutralizing potential of the tailings is minimal, since carbonate minerals are rare. The continuity of the tabular ore bodies, such as those of the Witwatersrand Basin, has allowed these mines to be the deepest in

Morphology and composition of gold in a lateritic profile, Fazenda Pison “Garimpo”, Amazon, Brazil

Science.gov (United States)

Larizzatti, J. H.; Oliveira, S. M. B.; Butt, C. R. M.

2008-05-01

This study describes the morphological evolution of gold grains in a lateritic weathering profile in an equatorial rainforest climate. Primary sources of gold are quartz veins associated with shallow granophyric intrusion. Gold grains were found in fresh ore, saprolite, transition zones, ferruginous duricrust, red latosol, and yellow latosol. Irregularly shaped grains predominate, with smaller proportions of dendritic and prismatic forms. Gold grains are weathered in the uppermost 10 m of the regolith. Mean gold grain size is maximum in the duricrust (>125 μm) and decreases progressively upward into the yellow latosol (duricrust formation may preserve some grains as large aggregates, but subsequent transformation into latosol further modifies them.

Photochemical Synthesis and Properties of Colloidal Copper, Silver and Gold Adsorbed on Quartz

International Nuclear Information System (INIS)

Loginov, Anatoliy V.; Gorbunova, Valentina V.; Boitsova, Tatiana B.

2002-01-01

Original methods for the photochemical production of stable copper, silver and gold colloids in the form of films on quartz, and dispersion in liquids were devised. It is shown that photochemical synthesis of colloidal metals is a difficult multiphase process, and includes the formation of low-valence forms of Cu(I), Au(I) and nonmetal clusters, colloidal particles and their agglomerates. Cluster stabilization and further growth to colloidal particles are achieved by adsorption onto the solid surface (quartz) or by increasing the viscosity of photolyte. In the absence of these methods of stabilization, the processes of intermediate reoxidation to Cu(II) and Au(III) and agglomeration of Ag and Au colloids proceed in a photolyte. Adsorption and the rate of cluster growth on a quartz surface are speeded up by the action of monochromatic UV light. Experimental models of the mechanism of colloidal formation are suggested. The dependence of the growth rate and the properties of the colloids on conditions of the photochemical procedure (energy and light intensity, concentration of initial complex) has been established

Colorado quartz: occurrence and discovery

Science.gov (United States)

Kile, D.E.; Modreski, P.J.; Kile, D.L.

1991-01-01

The many varieties and associations of quartz found throughout the state rank it as one of the premier worldwide localities for that species. This paper briefly outlines the historical importance of the mineral, the mining history and the geological setting before discussing the varieties of quartz present, its crystallography and the geological enviroments in which it is found. The latter include volcanic rocks and near surface igneous rocks; pegmatites; metamorphic and plutonic rocks; hydrothermal veins; skarns and sedimentary deposits. Details of the localities and mode of occurrence of smoky quartz, amethyst, milky quartz, rock crystal, rose quartz, citrine, agate and jasper are then given. -S.J.Stone

Mineralization and trace element distribution in pyrite using EMPA in exploration drill holes from Cheshmeh Zard gold district, Khorasan Razavi Province, Iran

Directory of Open Access Journals (Sweden)

Zahra Alaminia

2015-10-01

systems were recognized east of Arghash. The estimated resources are about 2 million metric tons of potential ore with an average of 1.9 g/t Au (Samadi, 2001;Ashrafpour et al., 2012. Multiple intrusive events are recognized in the region including Precambrian to post-Oligocene-Miocene igneous rocks (Alaminia et al., 2013a. This includes the Arghash diorite pluton, upper Cretaceous granitoids (minor diorite, mainly quartz monzodiorite and granodiorite, early Eocene granite and several lamprophyre and small intrusions of quartz monzodiorite porphyries. Volcanicsinclude andesite, dacite, pillow basalt and tuffs. Sedimentary rocks are conglomerate and minor limestone. Gold veins are hosted by intermediate to silicic volcanic rocks, tuffs, granite, granodiorite, and conglomerate. Veins consist of calcite and quartz. The main alteration zones mapped at the surface and underground are sericite-quartz-pyrite-calcite, withsilicified, propylitic, argillic, and carbonate zones. The mineralization associated with sericiticalteration and silicificationoccurs asveinlets and disseminated in the propylitic zone. Gangue minerals are quartz, chalcedony, calcite, adularia, illite, and kaolinite. Mineralization occurs as veinlets, breccia filling and disseminated. The veinlets are comprised of pyrite, arsenopyrite, minor chalcopyrite, sphalerite, galena, magnetite and hematite. Pyrite is the main sulfide mineral in the hypogene ore. Samples were collected with the objective of studying the pyrite in the Au (III vein systems. All samples were therefore pyrite rich. The paragenesiswas determined to show four stages of mineralization based on the following microscopic observations: 1. an initial pyrite veinlet stage with associated quartz, chlorite, epidote. Pyrite is fine to medium grained, anhedral and gold-poor. 2. a second pyritic stage (polymetallic sulfide stage contains pyrite, chalcopyrite, galena, sphalerite, quartz and chalcedony, minor adularia and arsenopyrite. 3. An As

From granulite fluids to quartz-carbonate megashear zones: The gold rush

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Bin Fu

2014-09-01

Full Text Available At peak granulite-facies metamorphic conditions, lower continental crust is arguably fluxed by large amounts of two key low water activity fluids: (i high-density CO2 and/or (ii concentrated saline solutions. These fluids are either internally-derived, generated by mineral reactions or dehydration melting or, notably for CO2, externally-derived, issued from the underlying mantle. Postmetamorphic evolution results in complete disappearance of these fluids, except for minute remnants preserved in minerals as fluid inclusions. Two major processes are involved: (i at peak conditions, granitoid magmas form, migrate upward, and crystallize as shallow intrusions in the upper crust (mineralized porphyry types or reduced intrusions; (ii during the rapid decompression which almost systematically follows a period of post-peak isobaric cooling, especially for ultrahigh-temperature granulites (anticlockwise P-T paths, quartz-carbonate megashear zones are formed by repeated periods of seismic activity. Seismic activity may continue until all free fluids have disappeared, resulting in the ultramylonites and pseudotachylites that are found in many granulite domes. A great majority of vein-type Au deposits worldwide occur in the above-mentioned settings or nearby. We suggest that the Au has been scavenged by the granulite fluids, then redistributed and concentrated during the formation of veins and related phenomena.

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Numerous younger thin quartz veins with somewhat similar orientation cut across the giant quartz veins. They show imprints of strong brittle to ductile–brittle deformation, and in places are associated with base metal and gold incidences, and pyrophyllite-diaspore mineralization. The geochemistry of giant quartz veins were ...

A natural example of fluid-mediated brittle-ductile cyclicity in quartz veins from Olkiluoto Island, SW Finland

Science.gov (United States)

Marchesini, Barbara; Garofalo, Paolo S.; Viola, Giulio; Mattila, Jussi; Menegon, Luca

2017-04-01

Brittle faults are well known as preferential conduits for localised fluid flow in crystalline rocks. Their study can thus reveal fundamental details of the physical-chemical properties of the flowing fluid phase and of the mutual feedbacks between mechanical properties of faults and fluids. Crustal deformation at the brittle-ductile transition may occur by a combination of competing brittle fracturing and viscous flow processes, with short-lived variations in fluid pressure as a viable mechanism to produce this cyclicity switch. Therefore, a detailed study of the fluid phases potentially present in faults can help to better constrain the dynamic evolution of crustal strength within the seismogenic zone, as a function of varying fluid phase characteristics. With the aim to 1) better understand the complexity of brittle-ductile cyclicity under upper to mid-crustal conditions and 2) define the physical and chemical features of the involved fluid phase, we present the preliminary results of a recently launched (micro)structural and geochemical project. We study deformed quartz veins associated with brittle-ductile deformation zones on Olkiluoto Island, chosen as the site for the Finnish deep repository for spent nuclear fuel excavated in the Paleoproterozoic crust of southwestern Finland. The presented results stem from the study of brittle fault zone BFZ300, which is a mixed brittle and ductile deformation zone characterized by complex kinematics and associated with multiple generations of quartz veins, and which serves as a pertinent example of the mechanisms of fluid flow-deformation feedbacks during brittle-ductile cyclicity in nature. A kinematic and dynamic mesostructural study is being integrated with the detailed analysis of petrographic thin sections from the fault core and its immediate surroundings with the aim to reconstruct the mechanical deformation history along the entire deformation zone. Based on the observed microstructures, it was possible to

Gas chromatography of indium in macroscopic and carrier-free amounts using quartz and gold as stationary phases

Energy Technology Data Exchange (ETDEWEB)

Serov, A.; Eichler, R.; Tuerler, A.; Wittwer, D.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. fuer Radiochemie und Umweltchemie; Bern Univ. (Switzerland). Dept. fuer Chemie und Biochemie; Dressler, R.; Piguet, D.; Voegele, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. fuer Radiochemie und Umweltchemie

2011-07-01

The chemical investigation of E113 is likely to become soon feasible. The determination of chemical properties of carrier-free amounts of the lighter homologues of element 113, especially indium and thallium, allows designing experimental set-ups and selecting experimental conditions suitable for performing these studies. Here, we present investigations of the interaction of indium species with quartz and gold surfaces. Deposition temperatures as well as enthalpies of adsorption were determined for indium T{sub dep} = 739 {+-} 20 C (-{delta}H{sub ads}(In) = 227 {+-} 10 kJ mol{sup -1}) and for indium hydroxide T{sub dep} = 250 {+-} 20 C (-{delta}H{sub ads}(InOH)= 124 {+-}10 kJ mol{sup -1}) respectively, on quartz. In case of adsorption of indium on a gold surface only a lower limit of the deposition temperature was established T{sub dep} > 980 C (-{delta}H{sub ads}(In) {>=} 315 {+-} 10 kJ mol{sup -1}). Investigations of macroscopic amounts of indium in thermosublimation experiments at similar experimental conditions were instrumental to establish a tentative speciation of the observed indium species. (orig.)

Mineralogy of the epithermal precious and base metal deposit Banská Hodruša at the Rozália Mine (Slovakia)

Science.gov (United States)

Kubač, Alexander; Chovan, Martin; Koděra, Peter; Kyle, J. Richard; Žitňan, Peter; Lexa, Jaroslav; Vojtko, Rastislav

2018-03-01

The Au-Ag-Pb-Zn-Cu epithermal deposit Banská Hodruša of intermediate-sulphidation type is located in the Middle Miocene Štiavnica stratovolcano on the inner side of the Carpathian arc in Slovakia. This deposit represents an unusual subhorizontal multi-stage vein system, related to processes of underground cauldron subsidence and exhumation of a subvolcanic granodiorite pluton. Veins are developed on a low-angle normal shear zone, possibly representing a detachment zone in andesitic wall rocks that formed during emplacement and exhumation of the granodiorite pluton. The deposit consists of two parts, separated by a thick sill of quartz-diorite porphyry. The eastern part is currently mined, and the western part has already been depleted. The Banská Hodruša mineralization was formed during four stages: (1) low-grade silicified breccia at subhorizontal structures at the base of the deposit; (2) stockwork of steep veins with rhodonite-rhodochrosite, quartz-sulphide-carbonate and quartz-gold assemblages; (3) thin quartz-gold veins with medium dip in tension cracks inside the shear zone and complementary detachment hosted quartz-base metals-gold veins; (4) Post-ore veins. Gold and electrum (920-730) occur as intergrowths with base metal sulphides or hosted in quartz and carbonates, accompanied by Au-Ag tellurides (hessite, petzite). Rare Te-polybasite and Cu-cervelleite result from re-equilibration of early Te-bearing minerals during cooling. Sulphide minerals include low Fe sphalerite ( 1.25 wt%), galena, chalcopyrite, and pyrite. The wall rock alteration is represented mostly by adularia, illite, chlorite, quartz, calcite and pyrite. Precipitation of gold, Au-Ag tellurides, Mn-bearing minerals and adularia resulted from boiling of fluids due to hydraulic fracturing, as well as opening of dilatational structures within the shear zone.

Orogenic-type copper-gold-arsenic-(bismuth) mineralization at Flatschach (Eastern Alps), Austria

Science.gov (United States)

Raith, Johann G.; Leitner, Thomas; Paar, Werner H.

2015-10-01

Structurally controlled Cu-Au mineralization in the historic Flatschach mining district (Styria, Austria) occurs in a NE-SW to NNE-WSW oriented vein system as multiple steep-dipping calcite-(dolomite)-quartz veins in amphibolite facies metamorphic rocks (banded gneisses/amphibolites, orthogneisses, metagranitoids) of the poly-metamorphosed Austroalpine Silvretta-Seckau nappe. Vein formation postdated ductile deformation events and Eoalpine (Late Cretaceous) peak metamorphism but predated Early to Middle Miocene sediment deposition in the Fohnsdorf pull-apart basin; coal-bearing sediments cover the metamorphic basement plus the mineralized veins at the northern edge of the basin. Three gold-bearing ore stages consist of a stage 1 primary hydrothermal (mesothermal?) ore assemblage dominated by chalcopyrite, pyrite and arsenopyrite. Associated minor minerals include alloclasite, enargite, bornite, sphalerite, galena, bismuth and matildite. Gold in this stage is spatially associated with chalcopyrite occurring as inclusions, along re-healed micro-fractures or along grain boundaries of chalcopyrite with pyrite or arsenopyrite. Sericite-carbonate alteration is developed around the veins. Stage 2 ore minerals formed by the replacement of stage 1 sulfides and include digenite, anilite, "blue-remaining covellite" (spionkopite, yarrowite), bismuth, and the rare copper arsenides domeykite and koutekite. Gold in stage 2 is angular to rounded in shape and occurs primarily in the carbonate (calcite, Fe-dolomite) gangue and less commonly together with digenite, domeykite/koutekite and bismuth. Stage 3 is a strongly oxidized assemblage that includes hematite, cuprite, and various secondary Cu- and Fe-hydroxides and -carbonates. It formed during supergene weathering. Stage 1 and 2 gold consists mostly of electrum (gold fineness 640-860; mean = 725; n = 46), and rare near pure gold (fineness 930-940; n = 6). Gold in stage 3 is Ag-rich electrum (fineness 350-490, n = 12), and has a

Evolution of supercritical fluid in deeply subducted continental crust: a case study of composite granite-quartz veins in the Sulu belt, China

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Wang, S.; Wang, L.; Brown, M.

2016-12-01

Although fluid plays a key role in element transport and rock strength during subduction to and exhumation from ultrahigh pressure (UHP) metamorphic conditions, the source of supercritical fluid at P above the second critical endpoints (SCE) and the subsequent evolution are not well constrained. To provide insight into the evolution of supercritical fluid in continental subduction zones, we undertook an integrated study of composite granite-quartz veins in retrogressed and migmatitic UHP eclogite at General's Hill, N of Qingdao, in the central Sulu belt. The composite veins are irregularly distributed in the eclogite, which occurs as blocks within gneiss. The granite component is enriched in large ion lithophile elements and light rare earth elements but depleted in high field strength elements and heavy rare earth elements, indicating crystallization from a melt phase of crustal origin. Additionally, the granite contains high modal phengite (22-30 vol%) and clinozoisite/epidote (3-10 vol%), implying precipitation from a H2O-rich silicate melt. By contrast, the quartz component is dominated by SiO2 (99.10 wt%), and contains low total rare earth elements (ΣREE = 0.46 ppm), indicating precipitation from an aqueous fluid. The crystallization age of the composite veins is 221 ± 2 Ma, which is younger than the UHP metamorphism in the Sulu belt at ca 230 Ma, consistent with formation during exhumation. Initial 176Hf/177Hf ratios and δ18O values of metamorphic zircons from the composite veins, and Sr-Nd isotope compositions of the granites all lie between values for eclogite and gneiss, indicating a mixed source. Accordingly, we propose that a supercritical fluid generated from the gneiss and the included blocks of eclogite at P-T conditions above the SCE for both compositions became trapped in the eclogite during exhumation. At P below the SCE for the hydrous granite system, the mixed supercritical fluid separated into immiscible aqueous melt and aqueous fluid and

The magmatic model for the origin of Archean Au-quartz vein ore systems: an assessment of the evidence

International Nuclear Information System (INIS)

Spooner, E.T.C.

1991-01-01

The magmatic model for the origin of Archean Au-quartz vein ore systems suggests that Au was derived by partition between silicate (± sulphide) melts of certain compositions and H 2 O-CO 2 -NaCl magmatic fluids. Supporting evidence includes partial/structural geological relationships, timing relationships, H and C isotope geochemistry, probable primary Au enrichment in the Lamaque stocks, and fluid inclusion volatile geochemistry. Evidence is currently negative with respect to various within- and sub-greenstone belt metamorphic/deep crustal fluid models for primary Au mineralization; however a U-Pb age for vein stage 3 sphene from the Camflo deposit, Quebec which is ∼ 55-60 Ma younger than the host stock at 2685-2680 Ma indicates dissolution/reprecipitation of Au by late, (?) upper crustal saline fluids. Evidence is accumulating that epithermal-meso thermal Au-Ag mineralization in island arc and cordilleran settings may also have been magmatically derived ± high level fluid mixing from calc-alkaline, shoshonitic and other igneous compositions. (author)

Elementary and isotopic geochemistry of vein goethite in laterite-gossanic crusts from the Igarape Bahia gold mine (Carajas, Brazil)

International Nuclear Information System (INIS)

Costa, Marcondes Lima da; Schumann, Thomas; Poellmann, Herbert

1996-01-01

The lateritic crusts of the gold mine from the Igarape Bahia, in Carajas, situated at Para state, Brazil, present themselves frequently sectioned by the goethite sub-vertical veins. The veins have the following measures: until 10 cm of thickness and more than 6 m of length. This work aims to characterize the textural, mineralogical and chemical aspects of these veins, in order to understand its evolution, mainly the relation with the laterites and its geological importance, including the aspects referents to the mineral prospecting. (author)

Simultaneous detection of surface coverage and structure of krypton films on gold by helium atom diffraction and quartz crystal microbalance techniques.

Science.gov (United States)

Danışman, M Fatih; Özkan, Berrin

2011-11-01

We describe a quartz crystal microbalance setup that can be operated at low temperatures in ultra high vacuum with gold electrode surfaces acting as substrate surface for helium diffraction measurements. By simultaneous measurement of helium specular reflection intensity from the electrode surface and resonance frequency shift of the crystal during film adsorption, helium diffraction data can be correlated to film thickness. In addition, effects of interfacial viscosity on the helium diffraction pattern could be observed. To this end, first, flat gold films on AT cut quartz crystals were prepared which yield high enough helium specular reflection intensity. Then the crystals were mounted in the helium diffractometer sample holder and driven by means of a frequency modulation driving setup. Different crystal geometries were tested to obtain the best quality factor and preliminary measurements were performed on Kr films on gold surfaces. While the crystal structure and coverage of krypton films as a function of substrate temperature could successfully be determined, no depinning effects could be observed. © 2011 American Institute of Physics

Geological and geochemical implications of the genesis of the Qolqoleh orogenic gold mineralisation, Kurdistan Province (Iran)

Science.gov (United States)

Taghipour, Batoul; Ahmadnejad, Farhad

2015-03-01

The Qolqoleh gold deposit is located in the northwestern part of the Sanandaj-Sirjan Zone (SSZ), within the NE-SW trending Qolqoleh shear zone. Oligocene granitoids, Cretaceous meta-limestones, schists and metavolcanics are the main lithological units. Chondrite-normalised REE patterns of the ore-hosting metavolcanics indicate REE enrichment relative to hanging wall (chlorite-sericite schist) and footwall (meta-limestone) rocks. The pattern also reflects an enrichment in LREE relative to HREE. It seems that the LREE enrichment is related to the circulation of SO42- and CO2-bearing fluids and regional metamorphism in the Qolqoleh shear zone. Both positive and negative Eu anomalies are observed in shear-zone metavolcanics. These anomalies are related to the degree of plagioclase alteration during gold mineralisation and hydrothermal alteration. In progressing from a metavolcanic protomylonite to an ultramylonite, significant changes occurred in the major/trace element and REE concentration. Utilising an Al-Fe-Ti isocon for the ore-hosting metavolcanics shows that Sc, Y, K, U, P, and M-HREE (except Eu) are relatively unchanged; S, As, Ag, Au, Ca, LOI, Rb and LREE are enriched, and Sr, Ba, Eu, Cr, Co and Ni decrease with an increasing degree of deformation. Based on geochemical features and comparison with other well-known shear zones in the world, the study area is best classified as an Isovolume-Gain (IVG) type shear zone and orogenic type gold mineralisation. Based on the number of phases observed at room temperature and their microthermometric behaviour, three fluid inclusion types have been recognised in quartz-sulphide and quartz-calcite veins: Type I monophase aqueous inclusions, Type II two-phase liquid-vapour (L-V) inclusions which are subdivided into two groups based on the homogenisation temperature (Th): a) L-V inclusions with Th from 205 to 255°C and melting temperature of last ice (Tm) from -3 to -9°C. b) L-V inclusions with higher Th from 335 to 385�

Magmatic-dominated fluid evolution in the Jurassic Nambija gold skarn deposits (southeastern Ecuador)

Science.gov (United States)

Vallance, Jean; Fontboté, Lluís; Chiaradia, Massimo; Markowski, Agnès; Schmidt, Susanne; Vennemann, Torsten

2009-05-01

The Jurassic (approximately 145 Ma) Nambija oxidized gold skarns are hosted by the Triassic volcanosedimentary Piuntza unit in the sub-Andean zone of southeastern Ecuador. The skarns consist dominantly of granditic garnet (Ad20-98) with subordinate pyroxene (Di46-92Hd17-42Jo0-19) and epidote and are spatially associated with porphyritic quartz-diorite to granodiorite intrusions. Endoskarn is developed at the intrusion margins and grades inwards into a potassic alteration zone. Exoskarn has an outer K- and Na-enriched zone in the volcanosedimentary unit. Gold mineralization is associated with the weakly developed retrograde alteration of the exoskarn and occurs mainly in sulfide-poor vugs and milky quartz veins and veinlets in association with hematite. Fluid inclusion data for the main part of the prograde stage indicate the coexistence of high-temperature (500°C to >600°C), high-salinity (up to 65 wt.% eq. NaCl), and moderate- to low-salinity aqueous-carbonic fluids interpreted to have been trapped at pressures around 100-120 MPa, corresponding to about 4-km depth. Lower-temperature (510-300°C) and moderate- to low-salinity (23-2 wt.% eq. NaCl) aqueous fluids are recorded in garnet and epidote of the end of the prograde stage. The microthermometric data (Th from 513°C to 318°C and salinity from 1.0 to 23 wt.% eq. NaCl) and δ18O values between 6.2‰ and 11.5‰ for gold-bearing milky quartz from the retrograde stage suggest that the ore-forming fluid was dominantly magmatic. Pressures during the early retrograde stage were in the range of 50-100 MPa, in line with the evidence for CO2 effervescence and probable local boiling. The dominance of magmatic low-saline to moderately saline oxidizing fluids during the retrograde stage is consistent with the depth of the skarn system, which could have delayed the ingression of external fluids until relatively low temperatures were reached. The resulting low water-to-rock ratios explain the weak retrograde alteration

Determination of gold by neutron activation analysis in some selected precambrian rocks from Eastern India

International Nuclear Information System (INIS)

Das, N.R.; Bhattacharyya, S.N.; Chakraborty, P.S.

1976-01-01

Gold was determined in epidiorite schist from Kunderkocha, in green phyllite from near Sausel in granodiorite from Kunderkocha and in galena quartz vein from Sausel by neutron activation analysis. The analysis was carried out both in destructive and non-destructive ways followed by γ-ray spectrometry. The process of preconcentration involves digestion of the rock samples with hydrofluoric acid and its dissolution in aqua regia solution, extraction of gold from the aqua regia solution by methylisobutyl ketone, back extraction of gold from the organic to the aqueous layer, and coprecipitation of gold by a known amount (0.7 g) of lead sulphide. The amounts of gold that were determined in the respective rock samples varied in the range 10 -4 -10 -6 %. Besides gold, some other trace constituents such as As, Ag, Sb, W, Se, La, Sn, etc. were also detected and their approximate order of occurence was determined. (T.G.)

Structural geology mapping using PALSAR data in the Bau gold mining district, Sarawak, Malaysia

Science.gov (United States)

Pour, Amin Beiranvand; Hashim, Mazlan

2014-08-01

The application of optical remote sensing data for geological mapping is difficult in the tropical environment. The persistent cloud coverage, dominated vegetation in the landscape and limited bedrock exposures are constraints imposed by the tropical climate. Structural geology investigations that are searching for epithermal or polymetallic vein-type ore deposits can be developed using Synthetic Aperture Radar (SAR) remote sensing data in tropical/sub-tropical regions. The Bau gold mining district in the State of Sarawak, East Malaysia, on the island of Borneo has been selected for this study. The Bau is a gold field similar to Carlin style gold deposits, but gold mineralization at Bau is much more structurally controlled. Geological analyses coupled with the Phased Array type L-band Synthetic Aperture Radar (PALSAR) remote sensing data were used to detect structural elements associated with gold mineralization. The PALSAR data were used to perform lithological-structural mapping of mineralized zones in the study area and surrounding terrain. Structural elements were detected along the SSW to NNE trend of the Tuban fault zone and Tai Parit fault that corresponds to the areas of occurrence of the gold mineralization in the Bau Limestone. Most of quartz-gold bearing veins occur in high-angle faults, fractures and joints within massive units of the Bau Limestone. The results show that four deformation events (D1-D4) in the structures of the Bau district and structurally controlled gold mineralization indicators, including faults, joints and fractures are detectable using PALSAR data at both regional and district scales. The approach used in this study can be more broadly applicable to provide preliminary information for exploration potentially interesting areas of epithermal or polymetallic vein-type mineralization using the PALSAR data in the tropical/sub-tropical regions.

Genetic Affiliation of Gold and Uranium Mineralization in El-Missikat Granite, Central Eastern Desert, Egypt

International Nuclear Information System (INIS)

Ammar, F.A.; Omar, S.A.M.; El Sawey, El.H.

2016-01-01

Gabal El-Missikat granitic pluton is affected by two fault systems trending NW-SE (the oldest) and ENE-WSW directions. It is one of the uranium occurrences in the Eastern Desert of Egypt. The northwestern margins of El-Missikat pluton, along its contact with the gneissose quartz diorite, are dissected by numerous reactivated fractured shear zones running generally ENE-WSW to NE-SW and dipping about 60°-70° to SE. Many white (oldest), smoky or black and jasperoid (youngest) silica veinlets fill the fractures of these shear zones. These veins are of irregular shape and variable thickness ranging from few centimeters to about three meters. They are chiefly affected by silicification, sericitization, hematitization , kaolinization and hydrothermal alterations processes. The smoky black veins are hosting secondary uranium and fluorite-, sulphide-gold mineralizations. Polished surface studies, ICP-ES and Atomic Absorption as well as Scanning Electron Microscope measurements recorded galena, pyrite chalcopyrite, sphalerite and molybdenite in the black and jasperoid mineralized veins. Gold associated with ore mineral assemblage as pyrite, chalcopyrite, sphalerite, galena, sheelite and iron oxides. The identified sulphide minerals not bearing gold are recorded. Gold are relatively coarse-grained, massive and metallic yellow or stretched bronze colored particles. The recorded secondary U minerals associates the sulphide gold-mineralization in the black and jasperoid silica veins. Regarding the mobility of both uranium and gold, U 4+ mobilized in oxidizing medium and migrate and transport as U 6+ , then deposited later as U 4+ when the medium changes to be reducing characterized by high /O 2 . On contrary, gold mobilized when the medium is complex AuCl 3- ion bearing. Consequently, El- Missikat granitic pluton affected by oxidizing Au and Cl 3- bearing high temperature hydrothermal solutions that leached U 4+ , W and Mo from the granitic mass as U 6 + , later decrease of

Improving the Outcome of Vein Grafts: Should Vascular Surgeons Turn Veins into Arteries?

OpenAIRE

Isaji, Toshihiko; Hashimoto, Takuya; Yamamoto, Kota; Santana, Jeans M.; Yatsula, Bogdan; Hu, Haidi; Bai, Hualong; Jianming, Guo; Kudze, Tambudzai; Nishibe, Toshiya; Dardik, Alan

2017-01-01

Autogenous vein grafts remain the gold standard conduit for arterial bypass, particularly for the treatment of critical limb ischemia. Vein graft adaptation to the arterial environment, i.e., adequate dilation and wall thickening, contributes to the superior performance of vein grafts. However, abnormal venous wall remodeling with excessive neointimal hyperplasia commonly causes vein graft failure. Since the PREVENT trials failed to improve vein graft outcomes, new strategies focus on the ada...

Isotopic studies of mariposite-bearing rocks from the south- central Mother Lode, California.

Science.gov (United States)

Kistler, R.W.; Dodge, F.C.W.; Silberman, M.L.

1983-01-01

Gold-bearing vein formation in the Mother Lode belt of the study area apparently occurred during the Early Cretaceous between 127 and 108 m.y. B.P. The hydrothermal fluids that carried the gold precipitated quartz and mariposite at approx 320oC, similar to the T of precipitation of gold-bearing quartz veins in the Allegheny district. The O- and H-isotopic composition calculated for the fluid indicate that it was similar to formation water or was metamorphic in origin. If the carbonate in the veins was in isotopic equilibrium with this same fluid, it apparently precipitated at a higher T of approx 400oC. The Sr in the carbonate is much less radiogenic than that in any known marine carbonate, but is similar in isotopic composition to that in metamorphosed mafic volcanic rocks of the general region. These mafic rocks could have been the source for the Sr in the hydrothermal veins. This observation supports the contention that the gold-mariposite-quartz-carbonate rocks were formed as an alteration product of serpentinite and other mafic igneous rocks.-A.P.

Genesis of the vein-type tungsten mineralization at Nyakabingo (Rwanda) in the Karagwe-Ankole belt, Central Africa

Science.gov (United States)

Dewaele, S.; De Clercq, F.; Hulsbosch, N.; Piessens, K.; Boyce, A.; Burgess, R.; Muchez, Ph.

2016-02-01

The vein-type tungsten deposit at Nyakabingo in the central Tungsten belt of Rwanda is located in the eastern flank of the complex Bumbogo anticlinal structure. The host rock is composed of alternating sequences of sandstones, quartzites, and black pyritiferous metapelitic rocks. Two types of W-mineralized quartz veins have been observed: bedding-parallel and quartz veins that are at high angle to the bedding, which are termed crosscutting veins. Both vein types have been interpreted to have been formed in a late stage of a compressional deformation event. Both vein types are associated with small alteration zones, comprising silicification, tourmalinization, and muscovitization. Dating of muscovite crystals at the border of the veins resulted in a maximum age of 992.4 ± 1.5 Ma. This age is within error similar to the ages obtained for the specialized G4 granites (i.e., 986 ± 10 Ma). The W-bearing minerals formed during two different phases. The first phase is characterized by scheelite and massive wolframite, while the second phase is formed by ferberite pseudomorphs after scheelite. These minerals occur late in the evolution of the massive quartz veins, sometimes even in fractures that crosscut the veins. The ore minerals precipitated from a H2O-CO2-CH4-N2-NaCl-(KCl) fluid with low to moderate salinity (0.6-13.8 eq. wt% NaCl), and minimal trapping temperatures between 247 and 344 °C. The quartz veins have been crosscut by sulfide-rich veins. Based on the similar setting, mineralogy, stable isotope, and fluid composition, it is considered that both types of W-mineralized quartz veins formed during the same mineralizing event. Given the overlap in age between the G4 granites and the mineralized quartz veins, and the typical association of the W deposits in Rwanda, but also worldwide, with granite intrusions, W originated from the geochemically specialized G4 granites. Intense water-rock interaction and mixing with metamorphic fluids largely overprinted the

Geological and Geochemical Criteria for the Estimation of the Area of The Lesser Hinggan for the Endogenous Gold Mineralization (The Far East, Russia)

Science.gov (United States)

Yurchenko, Yuriy

2015-04-01

intergrown with quartz, pyrite, arsenopyrite, galena in areas of intensive dislocation metamorphism and quartz-vein formation, accompanied by hydrothermal-metasomatic alteration of the bedrock in the mineral facies propylite, beresites and argillisites; 4. The transition some alluvial gold from lowland to the talus slope approaching the watershed areas; 5. The structural-geological similarity the area of the Lesser Hinggan with the gold mining areas of China and the northwestern part (Russia) of the Bureya array (Tandzhigou (Juanjiegou) (China), Noninskoe (Russia), Prognoznoe (Russia) and others). The Projected endogenous gold mineralization on the Lesser Hinggan include gold-quartz (including low-sulfide component) ore-formation type in the form of thin and not sustain the strike quartz veins in the surrounding strata (for example, gold deposit Lysoya Gora) and genetically related to the Early Cretaceous Hinggan-Olonoy complex of the subvolcanic felsic small intrusions . The ore-formation types associated with gold-bearing weathering crusts, carbon ("black") schist and ferruginous quartzite are the perspective in the area of the Lesser Hinggan also.

Citizen-Scientist Led Quartz Vein Investigation in the McDowell Sonoran Preserve, Scottsdale, Arizona, Resulting in Significant Geologic Discoveries and a Peer-Reviewed Report Coauthored and with Maps by Citizen-Scientists.

Science.gov (United States)

Gruber, D.; Gootee, B.

2016-12-01

Citizen-scientists of the McDowell Sonoran Conservancy Field Institute originated and led this project to study milky quartz deposits. Milky quartz veins of all sizes are visible throughout the McDowell Sonoran Preserve (Scottsdale, Arizona) and are commonly found in Arizona Proterozoic rocks. No research on milky quartz has been done locally and little is known about its formation and emplacement history. Working with Brian Gootee, research geologist with the Arizona Geological Survey (AZGS), a citizen science team identified candidate study sites with large quartz veins and then conducted aerial balloon photography followed by geologic mapping, basic data collection, photo-documentation, and sampling from two sites. Samples were analyzed with a UV lamp, Geiger counter, and x-ray fluorescence spectrometer. Petroscopic analysis and interpretation of the samples were done by Gootee. Daniel Gruber, the citizen-science project leader, and Gootee summarized methodology, sample analyses, and interpretation in a report including detailed geologic maps. Analysis of samples from one site provided evidence of several events of Proterozoic quartz formation. The other site hosted pegmatite, cumulates, graphic granite and orbicular granite in association with milky quartz, all discovered by citizen scientists. The milky quartz and surrounding pegmatites in granite at this site trace the progression of late-stage crystallization at the margin of a fractionated granite batholith, providing an exemplary opportunity for further research into batholith geochemistry and evolution. The project required 1000 hours of citizen-science time for training, field work, data organization and entry, mapping, and writing. The report by Gootee and Gruber was reviewed and published by AZGS as an Open File Report in its online document repository. The citizen scientist team leveraged the time of professional geologists to expand knowledge of an important geologic feature of the McDowell Mountains.

Field sampling scheme optimization using simulated annealing

CSIR Research Space (South Africa)

Debba, Pravesh

2010-10-01

Full Text Available : silica (quartz, chalcedony, and opal)→ alunite → kaolinite → illite → smectite → chlorite. Associated with this mineral alteration are high sulphidation gold deposits and low sulphidation base metal deposits. Gold min- eralization is located... of vuggy (porous) quartz, opal and gray and black chalcedony veins. Vuggy quartz (porous quartz) is formed from extreme leaching of the host rock. It hosts high sulphidation gold mineralization and is evidence for a hypogene event. Alteration...

Establishing linear solvation energy relationships between VOCs and monolayer-protected gold nanoclusters using quartz crystal microbalance.

Science.gov (United States)

Li, Chi-Lin; Lu, Chia-Jung

2009-08-15

Linear solvation energy relationships (LSERs) have been recognized as a useful model for investigating the chemical forces behind the partition coefficients between vapor molecules and absorbents. This study is the first to determine the solvation properties of monolayer-protected gold nanoclusters (MPCs) with different surface ligands. The ratio of partition coefficients/MPC density (K/rho) of 18 volatile organic compounds (VOCs) for four different MPCs obtained through quartz crystal microbalance (QCM) experiments were used for the LSER model calculations. LSER modeling results indicate that all MPC surfaces showed a statistically significant (pattraction, 4-methoxythiophenol-capped MPCs can also interact with polar organics (s=1.04). Showing a unique preference for the hydrogen bond basicity of vapors (b=1.11), 2-benzothiazolethiol-capped MPCs provide evidence of an intra-molecular, proton-shift mechanism on surface of nano-gold.

Oxygen isotope exchange with quartz during pyrolysis of silver sulfate and silver nitrate.

Science.gov (United States)

Schauer, Andrew J; Kunasek, Shelley A; Sofen, Eric D; Erbland, Joseph; Savarino, Joel; Johnson, Ben W; Amos, Helen M; Shaheen, Robina; Abaunza, Mariana; Jackson, Terri L; Thiemens, Mark H; Alexander, Becky

2012-09-30

Triple oxygen isotopes of sulfate and nitrate are useful metrics for the chemistry of their formation. Existing measurement methods, however, do not account for oxygen atom exchange with quartz during the thermal decomposition of sulfate. We present evidence for oxygen atom exchange, a simple modification to prevent exchange, and a correction for previous measurements. Silver sulfates and silver nitrates with excess (17)O were thermally decomposed in quartz and gold (for sulfate) and quartz and silver (for nitrate) sample containers to O(2) and byproducts in a modified Temperature Conversion/Elemental Analyzer (TC/EA). Helium carries O(2) through purification for isotope-ratio analysis of the three isotopes of oxygen in a Finnigan MAT253 isotope ratio mass spectrometer. The Δ(17)O results show clear oxygen atom exchange from non-zero (17)O-excess reference materials to zero (17)O-excess quartz cup sample containers. Quartz sample containers lower the Δ(17)O values of designer sulfate reference materials and USGS35 nitrate by 15% relative to gold or silver sample containers for quantities of 2-10 µmol O(2). Previous Δ(17)O measurements of sulfate that rely on pyrolysis in a quartz cup have been affected by oxygen exchange. These previous results can be corrected using a simple linear equation (Δ(17)O(gold) = Δ(17)O(quartz) * 1.14 + 0.06). Future pyrolysis of silver sulfate should be conducted in gold capsules or corrected to data obtained from gold capsules to avoid obtaining oxygen isotope exchange-affected data. Copyright © 2012 John Wiley & Sons, Ltd.

Mineralization and hydrothermal alteration of the Tajroud vein system, south of Neyshabour

Directory of Open Access Journals (Sweden)

Mohsen Alikhani Banghani

2013-10-01

Full Text Available The Tajroud vein system is located 190 km southwest of Mashhad, and in the southern part of the Sabzevar zone. The vein host rocks consist of Eocene intermediate to silicic volcanic rocks. The mineralization occurs as open space filling, taking place as veins, veinlets and hydrothermal breccias. Based on field geology and textural evidence, three main stages of mineralization were identified. Stage I mainly contains quartz, pyrite, chalcopyrite and magnetite. Stage II, which has the same mineral assemblage as stage I, is the most important stage in terms of volume. Finally, stage III is characterized by repetitive quartz and calcite banding with negligible amounts of sulfide minerals. Hydrothermal alteration is developed around the veins and tends to be more intense in the vicinity of the veins. The plot of the Ishikawa alteration index (AI versus chlorite-carbonate-pyrite index (CCPI, known as alteration box plot, displays three main alteration trends. The hydrothermal alteration assemblage of quartz, adularia, chlorite, illite, calcite, and epidote that envelops the Tajroud vein system formed from the upwelling of near-neutral to weakly alkaline hydrothermal solutions. The mineralogic, alteration and geochemical characteristics of the studied area and comparison with epithermal ore deposits indicate that the Tajroud vein system represents an epithermal system of low-sulfidation type.

Stable Isotopes (O, H, and S) in the Muteh Gold Deposit, Golpaygan Area, Iran

International Nuclear Information System (INIS)

Abdollahi, M. J.; Karimpour, M. H.; Kheradmand, A.; Zarasvandi, A. R.

2009-01-01

The Muteh gold district with nine gold deposits is located in the Sanandaj-Sirjan metamorphic zone. Gold mineralization occurs in a pre-Permian complex which mainly consists of green schists, meta-volcanics, and gneiss rocks. Shear zones are the host of gold mineralization. Gold paragenesis minerals include pyrite, chalcopyrite, pyrrhotite, and secondary minerals. Pyrites occur as pre-, syn-, and post-metamorphism minerals. To determine the source of the ore-bearing fluids, fifty samples were selected for petrographical and stable isotope studies. The mean values of 12.4 per mille , and -42 per mille for δ 18 O and δD isotopes, respectively, and a mean value of 7.75 per mille of calculated fractionation factors for δ 18 O H 2 O, from quartz veins indicate that metamorphic host rocks are the most important source for the fluids and gold mineralization. Three generations of pyrite can be distinguished showing a wide range of δ 34 S. Gold mineralization is closely associated with intense hydrothermal alteration along the ductile shear zones. The characteristics of the gold mineralization in the study area are similar to those of orogenic gold deposits elsewhere

Micrometer sized immobilization of protein molecules onto quartz, silicium and gold.

Science.gov (United States)

Petersen, Steffen B.; Neves-Petersen, Maria Teresa; Klitgaard, Søren; Duroux, Meg Crookshanks

2006-02-01

We demonstrate that ultraviolet light can be used to make sterically oriented covalent immobilization of a large variety of protein molecules onto either gold or thiolated quartz or silicium. The reaction mechanism behind the reported new technology involves light induced breakage of disulphide bridges in proteins upon UV illumination of nearby aromatic amino acids, resulting in the formation of free, reactive thiol groups that will form covalent bonds with thiol reactive surfaces. The protein molecules in general retain their function. The size of the immobilization spot is determined by the dimension of the UV beam. In principle, the spot size may be as small as 1 micrometer or less. We have developed the necessary technology for preparing large protein arrays of enzymes and fragments of monoclonal antibodies. Dedicated Image Processing Software has been developed for making quality assessment of the protein arrays. A multitude of important application areas such as drug carriers and drug delivery, bioelectronics, carbon nanotubes, nanoparticles as well as protein glue are discussed.

Fluid Inclusion Analysis of other Host Minerals besides Quartz: Application to Granite-Related Quartz-Topaz Veins and Garnet Skarns in Porphyry Copper-Gold Ore Systems

OpenAIRE

Schlöglova, Katerina

2018-01-01

Fluid inclusions are the only available samples of paleo-fluids responsible for crystallization of hydrothermal minerals including ore phases. Analysis of fluid inclusions implicitly assumes that the inclusions have preserved their chemical composition since the time of their entrapment. There is, however, an increasing evidence from experimental work and analytical studies of natural samples showing that inclusions hosted in quartz – a ubiquitous host in many ore-forming systems – can experi...

Telescoped porphyry-style and epithermal veins and alteration at the central Maratoto valley prospect, Hauraki Goldfield, New Zealand

International Nuclear Information System (INIS)

Simpson, M.P.; Mauk, J.L.; Kendrick, R.G.

2004-01-01

At the central Maratoto valley prospect, southern Coromandel Peninsula, New Zealand, andesite flows and dacite breccias host rare porphyry-style quartz veins that are telescoped by widespread epithermal veins and alteration. Early porphyry-style quartz veins, which lack selvages of porphyry-style alteration, host hypersaline fluid inclusions that contain several translucent daughter crystals, including halite and sylvite. Overprinting epithermal veins and alteration are divided into two stages. Main-stage epithermal alteration and veins are characterised by the successive deposition of pyrite, quartz, and ankerite-dolomite veinlets coupled with intense alteration of the wall rock to quartz, illite, interlayer illite-smectite (≤ 10% smectite), chlorite, pyrite, ankerite, and dolomite. Late-stage epithermal veins and alteration are characterised by the formation of calcite and siderite veinlets, coupled with overprinting of the wall rocks by both these minerals. Multiphase fluid inclusions in a porphyry-style quartz vein formed at temperatures >400 degrees C and trapped hypersaline magmatic fluid. Lower temperature secondary liquid-rich inclusions in the porphyry-style quartz vein homogenise between 283 and 329 degrees C and trapped a dilute fluid with 18 O (VSMOW) values of 13.5-18.1 permille, whereas late-stage epithermal calcite has δ 18 O (VSMOW) values of 3.1-5.1 permille. Calculated isotopic compositions for the fluid in equilibrium with ankerite-dolomite and calcite at 260 degrees C, averages 6 and -3 permille, respectively. The enriched value for main-stage ankerite-dolomite suggests formation from waters that underwent significant water-rock exchange, whereas isotopically lighter water that formed late-stage calcite underwent little water-rock interaction. We propose a three-stage model to explain telescoped veins and alteration styles at the central Maratoto valley prospect area. Porphyry-style quartz veins were the first to form from hot hypersaline

Paleostress and fluid-pressure regimes inferred from the orientations of Hishikari low sulfidation epithermal gold veins in southern Japan

Science.gov (United States)

Faye, Guillaume D.; Yamaji, Atsushi; Yonezu, Kotaro; Tindell, Thomas; Watanabe, Koichiro

2018-05-01

The orientation distribution of dilational fractures is affected by the state of stress around the fractures and by the pressure of the fluid that opened the fractures. Thus, the distribution can be inverted to determine not only the stress but also the pressure condition at the time of vein formation. However, epithermal ore veins that we observe today are the results of a great number of intermittent upwelling of overpressured fluids with different pressures. Here, we define driving pressure index (DPI) as the representative non-dimensionalized fluid pressure for the fluids. We collected the orientations of ∼1000 ore veins in the Hishikari gold mine, which were deposited at around 1 Ma, in southern Kyushu, Japan. It was found that the majority of the veins were deposited under an extensional stress with a NW-SE-trending σ3-axis and a northeasterly-inclined σ1-axis with relatively high stress ratio. The representative driving pressure ratio was ∼0.2. Data sets obtained at different depths in the mine indicated a positive correlation of representative driving pressure ratios with the depths. The correlation suggests repeated formation and break of pressure seals during the mineralization. Our compilation of the Pliocene-Quaternary stress regimes in southern Kyushu, including the result of the present study, suggests that epithermal gold mineralization was associated with distributed extensional deformations in southern Kyushu, and strain localization into an intra-arc rift seems to have terminated the mineralization.

Fluid inclusion study of the Witwatersrand gold-uranium ores

International Nuclear Information System (INIS)

Shepherd, T.J.

1977-01-01

Fluid inclusions, preserved in quartz pebbles of the uraniferous and auriferous Precambrian oligomictic conglomerates of the Witwatersrand Basin, provide a unique insight into the genesis of the ores. Using differences in inclusion characteristics in conjunction with intra- and inter-deformational textures for adjacent pebbles, a distinction is made between pre- and post-depositional inclusions. Excluding those related to subsequent brittle fracture, the former comprise five principal types; two of which are distinguished by the development of liquid carbon dioxide. Collectively they indicate a moderate to high pressure-temperature environment of vein quartz formation. Systematic variation in the relative abundance of these inclusion assemblages for different sections of the orefield demonstrates the importance of well-defined provenance areas or multiple entry points into the basins. A marked sympathetic relationship between uraniferous banket ores and the presence of vein quartz rich in liquid carbon dioxide inclusions, together with a corresponding antipathetic relationship for gold, strongly suggests separate sources for the metals. The temporal and spatial aspects of the association 'U-CO 2 ' also imply a uranium influx into the basin from discrete areas of the hinterland contemporaneous with the sediments. Post-depositional inclusions are subordinate and offer no support for the alternative epigenetic model and show only a later interaction of relatively cool circulating groundwaters. A discussion is given of the probable nature and origin of uranium in the source rocks and its mode of transportation. In conclusion, a proposal is made for the use of applied fluid inclusion research in the evaluation of and exploration for similar deposits. (author)

Transvaginal duplex ultrasonography appears to be the gold standard investigation for the haemodynamic evaluation of pelvic venous reflux in the ovarian and internal iliac veins in women.

Science.gov (United States)

Whiteley, M S; Dos Santos, S J; Harrison, C C; Holdstock, J M; Lopez, A J

2015-12-01

To assess the suitability of transvaginal duplex ultrasonography to identify pathological reflux in the ovarian and internal iliac veins in women. A retrospective study of patients treated in 2011 and 2012 was performed in a specialised vein clinic. Diagnostic transvaginal duplex ultrasonography in women presenting with symptoms or signs of pelvic vein reflux were compared with the outcomes of treatment from pelvic vein embolisation. A repeat transvaginal duplex ultrasonography was performed 6 weeks later by a blinded observer and any residual reflux was identified. Results from 100 sequential patients were analysed. Mean age 44.2 years (32-69) with mode average parity of 3 (0-5 deliveries). Pre-treatment, 289/400 veins were refluxing (ovarian - 29 right, 81 left; internal iliac - 93 right, 86 left). Coil embolisation was successful in 86/100 patients and failed partially in 14/100 - 5 due to failure to cannulate the target vein. One false-positive diagnosis was made. Currently there is no accepted gold standard for pelvic vein incompetence. Comparing transvaginal duplex ultrasonography with the outcome from selectively treating the veins identified as having pathological reflux with coil embolisation, there were no false-negative diagnoses and only one false-positive. This study suggests that transvaginal duplex ultrasonography could be the gold standard in assessing pelvic vein reflux. © The Author(s) 2014.

The Kharapeh orogenic gold deposit: Geological, structural, and geochemical controls on epizonal ore formation in West Azerbaijan Province, Northwestern Iran

Science.gov (United States)

Niroomand, Shojaeddin; Goldfarb, Richard J.; Moore, Farib; Mohajjel, Mohammad; Marsh, Erin E.

2011-01-01

The Kharapeh gold deposit is located along the northwestern margin of the Sanandaj–Sirjan Zone (SSZ) in the West Azerbaijan province, Iran. It is an epizonal orogenic gold deposit formed within the deformed zone between central Iran and the Arabian plate during the Cretaceous–Tertiary Zagros orogeny. The deposit area is underlain by Cretaceous schist and marble, as well as altered andesite and dacite dikes. Structural analysis indicates that the rocks underwent tight to isoclinal recumbent folding and were subsequently co-axially refolded to upright open folds during a second deformation. Late- to post-tectonic Cenozoic granites and granodiorites occur northeast of the deposit area. Mineralization mainly is recognized within NW-trending extensional structures as veins and breccia zones. Normal faults, intermediate dikes, and quartz veins, oriented subparallel to the axial surface of the Kharapeh antiform, indicate synchronous extension perpendicular to the fold axis during the second folding event. The gold-bearing quartz veins are >1 km in length and average about 6 m in width; breccia zones are 10–50 m in length and ≤1 m in width. Hydrothermal alteration mainly consists of silicification, sulfidation, chloritization, sericitization, and carbonatization. Paragenetic relationships indicate three distinct stages—replacement and silicification, brecciation and fracture filling, and cataclastic brecciation—with the latter two being gold-rich. Fluid inclusion data suggest mineral deposition at temperatures of at least 220–255°C and depths of at least 1.4–1.8 km, from a H2O–CO2±CH4 fluid of relatively high salinity (12–14 wt.% NaCl equiv.), which may reflect metamorphism of passive margin carbonate sequences. Ore fluid δ18O values between about 7‰ and 9‰ suggest no significant meteoric water input, despite gold deposition in a relatively shallow epizonal environment. Similarities to other deposits in the SSZ suggest that the deposit formed as

Geochemistry and statistical analyses of porphyry system and epithermal veins at Hizehjan in northwestern Iran

Directory of Open Access Journals (Sweden)

Radmard Kaikhosrov

2017-12-01

Full Text Available Situated about 130 km northeast of Tabriz (northwest Iran, the Mazra’eh Shadi deposit is in the Arasbaran metallogenic belt (AAB. Intrusion of subvolcanic rocks, such as quartz monzodiorite-diorite porphyry, into Eocene volcanic and volcano-sedimentary units led to mineralisation and alteration. Mineralisation can be subdivided into a porphyry system and Au-bearing quartz veins within andesite and trachyandesite which is controlled by fault distribution. Rock samples from quartz veins show maximum values of Au (17100 ppb, Pb (21100 ppm, Ag (9.43ppm, Cu (611ppm and Zn (333 ppm. Au is strongly correlated with Ag, Zn and Pb. In the Au-bearing quartz veins, factor group 1 indicates a strong correlation between Au, Pb, Ag, Zn and W. Factor group 2 indicates a correlation between Cu, Te, Sb and Zn, while factor group 3 comprises Mo and As. Based on Spearman correlation coefficients, Sb and Te can be very good indicator minerals for Au, Ag and Pb epithermal mineralisation in the study area. The zoning pattern shows clearly that base metals, such as Cu, Pb, Zn and Mo, occur at the deepest levels, whereas Au and Ag are found at higher elevations than base metals in boreholes in northern Mazra’eh Shadi. This observation contrasts with the typical zoning pattern caused by boiling in epithermal veins. At Mazra’eh Shadi, quartz veins containing co-existing liquid-rich and vapour-rich inclusions, as strong evidence of boiling during hydrothermal evolution, have relatively high Au grades (up to 813 ppb. In the quartz veins, Au is strongly correlated with Ag, and these elements are in the same group with Fe and S. Mineralisation of Au and Ag is a result of pyrite precipitation, boiling of hydrothermal fluids and a pH decrease.

Quartz-coesite-stishovite relations in shocked metaquartzites from the Vredefort impact structure, South Africa

Science.gov (United States)

Spray, John G.; Boonsue, Suporn

2018-01-01

Coesite and stishovite are developed in shock veins within metaquartzites beyond a radius of 30 km from the center of the 2.02 Ga Vredefort impact structure. This work focuses on deploying analytical field emission scanning electron microscopy, electron backscattered diffraction, and Raman spectrometry to better understand the temporal and spatial relations of these silica polymorphs. α-Quartz in the host metaquartzites, away from shock veins, exhibits planar features, Brazil twins, and decorated planar deformation features, indicating a primary (bulk) shock loading of >5 < 35 GPa. Within the shock veins, coesite forms anhedral grains, ranging in size from 0.5 to 4 μm, with an average of 1.25 μm. It occurs in clasts, where it displays a distinct jigsaw texture, indicative of partial reversion to a less dense SiO2 phase, now represented by microcrystalline quartz. It is also developed in the matrix of the shock veins, where it is typically of smaller size (<1 μm). Stishovite occurs as euhedral acicular crystals, typically <0.5 μm wide and up to 15 μm in length, associated with clast-matrix or shock vein margin-matrix interfaces. In this context, the needles occur as radiating or subparallel clusters, which grow into/over both coesite and what is now microcrystalline quartz. Stishovite also occurs as more blebby, subhedral to anhedral grains in the vein matrix (typically <1 μm). We propose a model for the evolution of the veins (1) precursory frictional melting in a microfault ( 1 mm wide) generates a molten matrix containing quartz clasts. This is followed by (2) arrival of the main shock front, which shocks to 35 GPa. This generates coesite in the clasts and in the matrix. (3) On initial shock release, the coesite partly reverts to a less dense SiO2 phase, which is now represented by microcrystalline quartz. (4) With continued release, stishovite forms euhedral needle clusters at solid-liquid interfaces and as anhedral crystals in the matrix. (5) With

Alteration and petrology of Intrusive Rocks associated with Gold Mineralization at Kuh-E-Zar Gold Deposit, Torbat-e-Heydaryeh

Directory of Open Access Journals (Sweden)

Alireza Mazloumi Bajestani

2009-09-01

Full Text Available Kuh- e -Zar gold deposit located 35 km west of Torbat-e-Heydaryeh, (Khorassan e- Razavi province, East of Iran. This deposit is a specularite-rich Iron oxide type (IOCG. This mine is situated within Khaf-Bardascan volcanic plutonic belt. Based on recent exploration along this belt, several IOCG type system plus Kuh-e-Zar deposit are discovered. In the study area, several type of tuff and lava having acid to intermediate composition are identified (upper Eocene. Oligo-Miocene granite, granodiorite, synogranite and monzonite intruded upper Eocene andesite-dacite-rhyolite. Intrusive rocks are meta-aluminous, medium to high-K series I-type. Based on spider diagram, intrusive rocks show enrichment in LILE = K, Th, Rb and depletion in HFSE = Nb, Sr, Ti. Based geochemistry of igneous rock, they formed in continental margin subduction zone. Propylitic (chlorite alteration is dominated and covers large area. Silicification is restricted only to mineralized zones. Argillic and albitization is found in certain location and cover small areas. The style of mineralization was controlled by the type and geometry of fault zones. Mineralization is found as vein, stockwork and breccias. Hypogene mineral Paragenesis include: specularite-quartz-gold-chlorite ± chalcopyrite ± pyrite ± galena ± barite. Secondary minerals formed due to oxidation are: goethite, limonite, lepidocrucite, Malachite, Azurite, Covelite, Cerucite, hydrocerucite, Pyrolusite and Smitsonite. In a few localities, chalcopyrite and minor pyrite and galena are found. Based on SEM analysis gold is present as electrum. Mineralization appeared in different type such as vein, stockwork and Hydrothermal breccia in strike sleep fault zone which are hidden inside volcano plutonic rocks. The average gold grade is between 3.02 ppm and ore reserve is estimated more than 3 million tons (cut off grade = 0.7 ppm.

Single-pulse and burst-mode ablation of gold films measured by quartz crystal microbalance

Science.gov (United States)

Andrusyak, Oleksiy G.; Bubelnik, Matthew; Mares, Jeremy; McGovern, Theresa; Siders, Craig W.

2005-02-01

Femtosecond ablation has several distinct advantages: the threshold energy fluence for the onset of damage and ablation is orders of magnitude less than for traditional nanosecond laser machining, and by virtue of the rapid material removal of approximately an optical penetration depth per pulse, femtosecond machined cuts can be cleaner and more precise than those made with traditional nanosecond or longer pulse lasers. However, in many materials of interest, especially metals, this limits ablation rates to 10-100 nm/pulse. We present the results of using multiple pulse bursts to significantly increase the per-burst ablation rate compared to a single pulse with the same integrated energy, while keeping the peak intensity of each individual pulse below the air ionization limit. Femtosecond ablation with pulses centered at 800-nm having integrated energy of up to 30 mJ per pulse incident upon thin gold films was measured via resonance frequency shifts in a gold-electrode-coated quartz-crystal oscillator. Measurements were performed using Michelson-interferometer-based burst generators, with up to 2 ns pulse separations, as well as pulse shaping by programmable acousto-optic dispersive filter (Dazzler from FastLite) with up to 2 ps pulse separations.

Fluid fractionation of tungsten during granite-pegmatite differentiation and the metal source of peribatholitic W quartz veins: Evidence from the Karagwe-Ankole Belt (Rwanda)

Science.gov (United States)

Hulsbosch, Niels; Boiron, Marie-Christine; Dewaele, Stijn; Muchez, Philippe

2016-02-01

The identification of a magmatic source for granite-associated rare metal (W, Nb, Ta and Sn) mineralisation in metasediment-hosted quartz veins is often obscured by intense fluid-rock interactions which metamorphically overprinted most source signatures in the vein system. In order to address this recurrent metal sourcing problem, we have studied the metasediment-hosted tungsten-bearing quartz veins of the Nyakabingo deposit of the Karagwe-Ankole belt in Central Rwanda. The vein system (992 ± 2 Ma) is spatiotemporal related to the well-characterised B-rich, F-poor G4 leucogranite-pegmatite suite (986 ± 10 Ma to 975 ± 8 Ma) of the Gatumba-Gitarama area which culminated in Nb-Ta-Sn mineralisation. Muscovite in the Nyakabingo veins is significantly enriched in granitophile elements (Rb, Cs, W and Sn) and show alkali metal signatures equivalent to muscovite of less-differentiated pegmatite zones of the Gatumba-Gitarama area. Pegmatitic muscovite records a decrease in W content with increasing differentiation proxies (Rb and Cs), in contrast to the continuous enrichment of other high field strength elements (Nb and Ta) and Sn. This is an indication of a selective redistribution for W by fluid exsolution and fluid fractionation. Primary fluid inclusions in tourmaline of these less-differentiated pegmatites demonstrate the presence of medium to low saline, H2O-NaCl-KCl-MgCl2-complex salt (e.g. Rb, Cs) fluids which started to exsolve at the G4 granite-pegmatite transition stage. Laser ablation inductively coupled plasma mass-spectrometry shows significant tungsten enrichment in these fluid phases (∼5-500 ppm). Fractional crystallisation has been identified previously as the driving mechanism for the transition from G4 granites, less-differentiated biotite, biotite-muscovite towards muscovite pegmatites and eventually columbite-tantalite mineralised pegmatites. The general absence of tungsten mineralisation in this magmatic suite, including the most differentiated

Evidence for de-sulfidation to form native electrum in the Fire Creek epithermal gold-silver deposit, north-central Nevada

Science.gov (United States)

Perez, J.; Day, J. M.; Cook, G. W.

2012-12-01

The Fire Creek property is a newly developed and previously unstudied epithermal Au-Ag deposit located in the Northern Shoshone range of north central Nevada. The mineralization occurs within and above en echelon N-NW trending basaltic dykes that are hosted within a co-genetic and bimodal suite of mid-Miocene basalts and andesites formed in association with the Yellowstone hotspot-track. Previous studies of Au-Ag mineralization in the Great Basin have focused primarily on extensively mined and/or low-grade deposits. Therefore, the ability for unrestricted sampling of a major Au-Ag deposit early in its exploration and development represents an opportunity for refined understanding of epithermal ore genesis processes. New petrology reveals at least two distinct pulses of mineralization that in relative order of timing are: 1) S-rich veins which are associated with initial host-rock alteration; 2) quartz- and/or calcite-rich veins which vary from fine-grained to lath-like quartz crystals with large calcite crystals in vein centers. Native electrum occurs only within the second phase of mineralization and typically occurs within quartz and adjacent to cross-cut first-phase S-rich veins. In places the electrum appears to replace or form overgrowths around existing sulfide phases. High levels of gold and silver are found in both the first (0.8 g Au/tonne) and second-phase pulses (37 g Au/tonne). Fire Creek shares many similarities with its northern neighbor, the Mule Canyon Au-Ag deposit, with high Fe sulfide contents for some of the ores, altered wall-rocks and the presence of narrow and discontinuous gold-bearing siliceous veins. Like Fire Creek, Mule Canyon possesses two distinct mineralizing phases, a sulfide rich and a late stage calcite/silica assemblage. The first pulse appears to be identical in both locations with a variation of disseminated to euhedral iron-sulfides and associated intense alteration of host rock. However, Fire Creek differs from Mule Canyon in

Gold grade of epithermal gold ore at Lamuntet, Brang Rea, West Sumbawa District, West Nusa Tenggara Province, Indonesia

Science.gov (United States)

Ernawati, Rika; Idrus, Arifudin; TBMP, Himawan

2017-06-01

Lamuntet is one of gold ore mining area carried out by the Artisanal Small scale Gold Mining (ASGM) located in West Sumbawa, Indonesia. Most of the miners at this area are not the local miners but also those from other regions. Mineralization of this area is strong identified as low sulfidation epithermal system. There are two blocks of this mining location, namely, Ngelampar block with an area of 0.164 km2 and Song block with an area of 0.067 km2. This study was focused on Ngelampar block. The characteristic of epithermal system is the existence of quartz vein with comb, vuggy, and sugary texture. The aim of this research was to analyze the gold grade and other metals, such as Cu, Ag, Pb, As, Zn, and Hg. The research methods included literature study from previous researches, field work, laboratory work, and interpretation. The literature study was performed on previous researches with similar study area. The field work comprised of direct observation and sampling. Fieldwork was done for a week to obtain gold ore/vein. Sixteen samples were analyzed to obtain the grade of ore/metal. The Hg laboratory analysis was then performed on the six samples with the highest gold grade. Laboratory works were conducted at Intertek Jakarta by using Fire Assay (FA) for gold grade and Atomic Absorption Spectrophotometry (AAS) for Cu, Ag, Pb, As, Zn, and Hg. Results of the analysis showed the range of Au was grade (0.1 ppm - 27.8 ppm), Cu was 26 ppm -1740 ppm, Pb was 101 ppm- >4000 ppm, Zn of 73 ppm- >10,000 ppm, Ag of 3 ppm -185 ppm, As was 150 ppm-6530 ppm, and Hg of 0.08 ppm - 1.89 ppm. L1 and L15 had high grade for all values (Au, Ag, Zn, Cu, As, and Hg). Gold mineralization was formed as electrum because of Ag content is higher than 20%. Associated minerals of the samples in the study area were galena, sphalerite, arsenopyrite, and chalcopyrite which showed the characteristic of rich base metal of Pb, Zn, and Cu at LS epithermal.

Stable isotope and fluid inclusion evidence for the origin of the Brandberg West area Sn-W vein deposits, NW Namibia

Science.gov (United States)

Macey, Paul; Harris, Chris

2006-10-01

The Brandberg West region of NW Namibia is dominated by poly-deformed turbidites and carbonate rocks of the Neoproterozoic Damara Supergoup, which have been regionally metamorphosed to greenschist facies and thermally metamorphosed up to mid-amphibolite facies by Neoproterozoic granite plutons. The meta-sedimentary rocks host Damaran-age hydrothermal quartz vein-hosted Sn-W mineralization at Brandberg West and numerous nearby smaller deposits. Fluid inclusion microthermometric studies of the vein quartz suggests that the ore-forming fluids at the Brandberg West mine were CO2-bearing aqueous fluids represented by the NaCl-CaCl2-H2O-CO2 system with moderate salinity (mean=8.6 wt% NaClequivalent).Temperatures determined using oxygen isotope thermometry are 415-521°C (quartz-muscovite), 392-447°C (quartz-cassiterite), and 444-490°C (quartz-hematite). At Brandberg West, the oxygen isotope ratios of quartz veins and siliciclastic host rocks in the mineralized area are lower than those in the rocks and veins of the surrounding areas suggesting that pervasive fluid-rock interaction occurred during mineralization. The O- and H-isotope data of quartz-muscovite veins and fluid inclusions indicate that the ore fluids were dominantly of magmatic origin, implying that mineralization occurred above a shallow granite pluton. Simple mass balance calculations suggest water/rock ratios of 1.88 (closed system) and 1.01 (open system). The CO2 component of the fluid inclusions had similar δ 13C to the carbonate rocks intercalated with the turbidites. It is most likely that mineralization at Brandberg West was caused by a combination of an impermeable marble barrier and interaction of the fluids with the marble. The minor deposits in the area have quartz veins with higher δ 18O values, which is consistent with these deposits being similar geological environments exposed at higher erosion levels.

Lattice location of gold in natural pyrite crystals

International Nuclear Information System (INIS)

Besten, Jacinta den; Jamieson, David N.; Ryan, Chris G.

1999-01-01

The lattice location of gold atoms in naturally occurring Au-doped pyrite crystals has been investigated with a nuclear microprobe using ion channeling. The specimens consisted of 300-μm diameter pyrite crystals in veins embedded in a quartz matrix from the Emperor mine in Fiji. The specimens were prepared by standard geological specimen preparation techniques and the pyrite crystals were analysed in situ in the quartz matrix. Significant trace elements in the crystals, determined by Proton Induced X-ray Emission with a 3 MeV H + microprobe, were Cu, As, Mo, Zn, Te, Au and Pb. The Au concentration was about 0.2 wt%. By the use of 2 MeV He + ion channeling, the Miller indices of the lowest order crystal axes nearest to the normal were determined from backscattering yield maps from two-dimensional angular scanning and comparison of the resulting patterns with published gnomonic projections. Channeling angular yield curves were obtained from Fe, S, As and Au signals. The results indicate that at least 35% of the Au is substituted onto lattice sites

Age of mineralization of the Nansatsu type gold deposits, Kagoshima, Japan

International Nuclear Information System (INIS)

Izawa, Eiji; Urashima, Yukitoshi; Okubo, Yoshikazu.

1984-01-01

Gold-bearing massive silicified rocks occur in the volcanic piles of the Neogene Tertiary age in the Makurazaki district, southern Kyushu and are termed as the Nansatsu type gold deposits. Currently three mines, Kasuga, Iwato and Akeshi, are operating. The argillized zones consisting mainly of quartz, kaolinite and minor goethite surround the silicified rocks. Alunite series minerals occur in and around the silicified rocks. Ages of mineralization have been discussed for many years but were unanswered. K-Ar dating of selected alunite and alunite-bearing rocks from three mines yields ages of 5.5 - 3.7 m.y. K-Ar ages at Mt. Sonomi of the Kasuga mine (5.5 +- 0.4 m.y.) and at the Arabira orebody of the Iwato mine (4.7 +- 1.0 m.y.) probably represent the ages of gold mineralization. Slightly younger ages at Mt. Iwato of the Iwato mine (4.4 +- 0.7 m.y.) and at the No. 1 orebody of the Akeshi mine (3.7 +- 1.1 m.y.) might reflect possible changes in chemical composition of alunite during weathering after mineralization. Gold-silver mineralization in southern Kyushu took place in the Pliocene to early Pleistocene, except minor silver-rich vein type deposits in the middle Miocene time. This study shows that four values are concordant with each other and indicate the latest Miocene to early Pliocene ages for mineralization of the Nansatsu type gold deposits in the Makurazaki district. The ages are comparable with the vein type gold deposits of the early Pliocene time such as Kushikino (4.0 +- 0.3 m.y.) and Hanakago (4.8 +- 2.9 m.y.). Another gold mineralization were known in the early Pleistocene time such as Hishikari (1.5 +- 0.3 m.y.) and Ora (1.8 +- 0.2 m.y.). At present there seems to be only minor gold mineralization between 4 and 2 m.y. (author)

Isotopic characteristics of two kinds of hydrothermal carbonation in the Maria Lazara gold deposit. Goias Estate of Central Brazil

International Nuclear Information System (INIS)

Pulz, G.; Fuck, R.

1998-01-01

In the hydrothermal halo of the Maria Lazara gold deposit, two kinds of carbonation were identified: pervasive carbonation, which corresponds to the disseminations of calcite in the hydrothermal halo represented by the biotite-sulfide and carbonate-chlorite zones and, venular carbonation expressed by quartz and calcite veins inserted in the inner biotite-sulfide zone show an organic carbon component depleted in C. In the carbonate-chlorite zone the calcite isotopic behavior reflects the Co2 derived from the metamorphism o the basic host-rocks. (author)

Polymetallic mineralised veins in ferroan/A-type Cretaceous leucogranite, Stewart Island, New Zealand

International Nuclear Information System (INIS)

Allibone, A.H.; MacKenzie, D.; Turnbull, R.E.; Tulloch, A.J.; Craw, D.; Palin, M.

2016-01-01

The 140±1 Ma hypersolvus, ferroan, weakly peralkaline to weakly peraluminous North Red Head leucogranite in northwest Stewart Island is cut by quartz-pyrite-rich veins that contain a wide variety of Mo, Ag, Te, Bi, Au, Co, Cu, Pb, Zn, REE, Nb, Y, Th, U, Zr, Ti, Be and F-bearing minerals. Patchy hematite-pyrite alteration locally overprints leucogranite in the vicinity of the mineralised veins. Individual veins are up to 5 m thick and 200+ m long. U-Pb dating and trace-element geochemistry indicate a direct link between leucogranite crystallisation and exsolution of the vein-forming hydrothermal fluid. Mineralised veins developed along transpressional faults within the leucogranite soon after emplacement. Incipiently mineralised quartz?±?pyrite veins at Waituna Bay and the northern end of West Ruggedy Beach several kilometres from North Red Head are probably part of the same hydrothermal system as the veins at North Red Head. Metal and alteration assemblages at North Red Head most closely resemble those in rare hydrothermal systems associated with oxidised fluorine-rich A-type granites. (author).

Are modern geothermal waters in northwest Nevada forming epithermal gold deposits?

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Breit, George N.; Hunt, Andrew G.; Wolf, Ruth E.; Koenig, Alan E.; Fifarek, Richard; Coolbaugh, Mark F.

2010-01-01

Hydrothermal systems currently are active near some gold deposits in northwestern Nevada. Possible links of these modern systems to gold mineralization were evaluated by chemically and isotopically analyzing water samples from the Brady, Dixie Valley, Humboldt House, San Emidio-Empire, Soda Lake, and Wabuska geothermal areas. In addition, quartz veins from Humboldt House and the adjacent Florida Canyon Mine were analyzed to compare ore and gangue phases with those predicted to form from proximal hydrothermal fluids.Nearly all water samples are alkali-chloride-type. Total dissolved solids range from 800 to 3900 mg/L, and pH varies from 5.6 to 7.8. Geochemical modeling with SOLVEQ, WATCH, and CHILLER predict the precipitation of silica in all systems during cooling. Anhydrite, calcite, barite, pyrite, base-metal sulfides, and alumino-silicates are variably saturated at calculated reservoir temperatures and also precipitate during boiling/cooling of some fluids. Measured dissolved gold concentrations are low (<0.2μg/L), but are generally consistent with contents predicted by equilibrium of sampled solutions with elemental gold at reservoir temperatures.  Although the modern geothermal waters can precipitate ore minerals, the low gold and other ore metal concentrations require very large fluid volumes to form a deposit of economic interest.

Interpretasi Mineralisasi Epitermal Berdasarkan Studi Ubahan Hidrotermal dan Tekstur Urat Kuarsa di Kawasan Hutan Lindung Taliwang, Nusa Tenggara Barat

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Danny Zulkifli Herman

2014-06-01

Full Text Available http://dx.doi.org/10.17014/ijog.vol2no3.20072Taliwang conservation forest, West Nusa Tenggara, is particularly covered by volcanic rocks consisting of alternated breccia and tuff. The breccia is composed of andesitic – dioritic clasts and matrix of fine-grained to lapilli tuff which had partially been hidrothermally altered and invaded by gold bearing quartz veins. Outcrops of quartz veins are commonly limonitized, trending nearly east-west and north-south with respectively dip of 70o and 85o. Identification of quartz veins originated from people mining’s waste leads to a prediction that there are quartz stockworks beneath the earth surface (50 – 100 m depth in the conservation forest area, from which quartz veins penetrated the illite-paragonite-calcite-siderite- nacrite altered country rock. Textures of quartz veins were identified such as comb with some coarse- grained euhedral crystals, sugary/saccharoidal/fine grained crystalline quartz and ghost-bladed. Veins and host rocks generally contain disseminated and spotted pyrites. Evaluation of quartz textures, altered rocks analysis (PIMA method, fluid inclusion studies and chemical analysis (AAS method of selective altered rocks/quartz vein samples exhibits that the alteration and mineralization processes might occur in an epithermal system, connecting with a change of hydrothermal fluids from near neutral into acid conditions at a temperature ranging from 231 to 185oC. Alteration of illite-paragonite-kalsit-siderite is suggested as a result of reaction between host rock and a near neutral fluid, whilst nacrite (kaolin group or argillic is a result of reaction between host rock and an acid fluid, within a mixing zone of meteoric fluid and condensed acid gas released during boiling process of hydrothermal fluid in the depth. On the basis of salinity ranging from 0.9 to 2.2 equivalent wt.% NaCl of fluid inclusion, it is predicted that the deposition of gold bearing quartz and associated

Structural controls and evolution of gold-, silver-, and REE-bearing copper-cobalt ore deposits, Blackbird district, east-central Idaho: Epigenetic origins

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Lund, K.; Tysdal, Russell G.; Evans, Karl V.; Kunk, Michael J.; Pillers, Renee M.

2011-01-01

The Cu-Co ± Au (± Ag ± Ni ± REE) ore deposits of the Blackbird district, east-central Idaho, have previously been classified as Besshi-type VMS, sedex, and IOCG deposits within an intact stratigraphic section. New studies indicate that, across the district, mineralization was introduced into the country rocks as a series of structurally controlled vein and alteration systems. Quartz-rich and biotite-rich veins (and alteration zones) and minor albite and siderite veinlets maintain consistent order and sulfide mineral associations across the district. Both early and late quartz veins contain chalcopyrite and pyrite, whereas intermediate-stage tourmaline-biotite veins host the cobaltite. Barren early and late albite and late carbonate (generally siderite) form veins or are included in the quartz veins. REE minerals, principally monazite, allanite, and xenotime, are associated with both tourmaline-biotite and late quartz veins. The veins are in mineralized intervals along axial planar cleavage, intrafolial foliation, and shears.

Two-stage structural development of a Paleozoic auriferous shear zone at the Globe-Progress deposit, Reefton, New Zealand

International Nuclear Information System (INIS)

Milham, L.; Craw, D.

2009-01-01

The Globe-Progress gold deposit at Reefton is hosted in a curvilinear mineralised zone that cuts Paleozoic Greenland Group basement metagreywackes. Two discrete phases of mineralisation have resulted in the formation of five different ore types along the shear. An initial phase of mineralisation formed hydrothermal quartz veins and associated Au, As, and S enrichment, with low-grade mineralised host rock. These quartz veins and mineralised host rocks form the outer regions of the mineralised zone. A second hydrothermal phase introduced Sb, Au, As, and S during brittle shear deformation focused on the pre-existing mineralised rocks. This deformation and mineralisation resulted in the formation of metre-scale cataclasite ore and quartz breccia from mineralised host rock and hydrothermal quartz veins, respectively. Cataclasite was derived from argillite layers in the host rock, from which Na, Fe, and Mg have been leached during mineralisation; Al, Ti, and Cr have been conserved; and there has been minor enrichment in Sr, Pb, Zn, and Cu. No quartz was added to the cataclasite or quartz breccia during mineralisation, but some quartz recrystallisation occurred locally, and quartz clasts were physically incorporated into the cataclasite during deformation. The presence of euhedral sulfides in the cataclasite (40% of total sulfides), late-stage undeformed stibnite veins infilling breccia (1-5 cm 3 scale), and undeformed free gold in quartz breccia, imply that the second phase of mineralisation persisted both during and after cataclasis and brecciation. Antimony deposition is greatest in the central cataclasite, up to 6 wt%, and locally in the quartz breccia where stibnite veins are present. Concentrations of Sb decrease with distance from the shear zone. The second, Sb-rich phase of mineralisation in the Globe-Progress deposit resembles similar Sb-rich overprints in the correlative Victorian goldfield of Australia. (author). 38 refs., 10 figs., 1 tab.

Transformation of Serpentinite to Listvenite as Recorded in the Vein History of Rocks From Oman Drilling Project Hole BT1B

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Manning, C. E.; Kelemen, P. B.; Michibayashi, K.; Harris, M.; Urai, J. L.; de Obeso, J. C.; Jesus, A. P. M.; Zeko, D.

2017-12-01

Oman Drilling Project Hole BT1B intersected 191 m of listvenite (magnesite + quartz rock) and serpentinite in the hanging wall of the basal thrust of the Oman ophiolite. Recovery was 100%. Listvenite is the dominant lithology in the upper plate rocks (166 m). Its shows wide color and textural variation, including pseudomorphic replacement of serpentinized peridotite. Serpentinite was encountered in two main contiguous intervals totaling 25 m. In light of the strongly metasomatic nature for the origin of listvenite, a substantial portion of the core description effort was dedicated to characterization of the complex veining history recorded in the hole. Dense veining is recorded in both lithologies. The density of 200/m. The density of veins >1 mm was 50-100/m, with somewhat higher densities recorded in serpentinite than in listvenite. In order of oldest to youngest, the main vein types in serpentinite are microscopic mesh-textured serpentine veins, macroscopic serpentine veins, carbonate-oxide veins, and carbonate veins. The vein paragenesis in listvenite is: early carbonate-oxide veins, followed by carbonate and carbonate-quartz veins, then late carbonate veins. The carbonate-oxide and carbonate veins are shared by the lithologies and hold clues to the transformation of ultramafic rocks to listvenite. Carbonate-oxide veins form a distinctive set that is interpreted to be the earliest record of carbonate formation in serpentinite. They contain Fe-oxide, usually hematite, on a medial line, with antitaxial magnesite crystals growing outward and showing terminations against wall rock minerals. Antitaxial textures may be evidence of positive reaction volumes. In serpentinite, secondary serpentine after earlier serpentine is common at vein margins. Carbonate-oxide veins are the earliest observed in listvenite, where they may form isolated veins to dense, aligned networks that impart a foliated texture. In some cases, they appear to predate replacement of serpentine by

Occurrences of dendritic gold at the McLaughlin Mine hot-spring gold deposit

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Sherlock, R. L.; Lehrman, N. J.

1995-06-01

Two styles of gold dendrites are variably developed at the McLaughlin Mine. The most abundant occurrence is hosted by amber-coloured hydrocarbon-rich opal. Silica likely precipitated from a boiling hydrothermal fluid and complexed with immiscible hydrocarbons forming an amorphous hydrocarbon-silica phase. This phase likely scavenged particulate gold by electrostatic attraction to the hydrocarbon-silica phase. The dendritic nature of the gold is secondary and is the result of dewatering of the amorphous hydrocarbon-silica phase and crystallization of gold into syneresis fractures. The second style of dendritic gold is hosted within vein swarms that focused large volumes of fluid flow. The dendrites occur along with hydrocarbon-rich silica at the upper contact of the vein margins which isolated the dendrites allowing sufficient time for them to grow. In a manner similar to the amber-coloured opal, the dendrites may have formed by scavenging particulate gold by electrostatic attraction to the hydrocarbon-silica phase.

Geochemical aspects of mineralization in the Sabie-Pilgrim's Rest goldfield, eastern Transvaal

International Nuclear Information System (INIS)

Boer, R.H.; Meyer, F.M.; Robb, L.J.

1990-01-01

The Sabie-Pilgim's Rest goldfield in the eastern Transvaal constitutes the third biggest gold source in South Africa. Mineralization is vein controlled and extends from the Archaean granite basement, through the pre-Transvaal Godwan and Wolkeberg sequences into the Transvaal Supergroup comprising the Chuniespoort and Pretoria Groups. Gold occurs predominantly in three styles, as stratiform quartz-gold lodes, as transgressive veins, and as structurally controlled quartz blows. The flat reefs which host the majority of gold and sulphide ores are dominated by quartz although calcite becomes an important constituent towards the edges of the deposits. δ 18 O values obtained on quartz associated with a variety of different styles of gold mineralization are typically enriched in δ 18 O relative to SMOW. A progressive increase in δ 18 O is apparent from the underlying Archaean granite basement through the vertical reefs to the horizontal reefs. The trend towards heavier δ 18 O is accompanied by an increase in fluid salinity. The trend towards heavier δ 18 O and the increased salinity upwards in the stratigraphy is explained by the mixing of low salinity magmatic water from the granitic basement, with formation waters of the Transvaal basin. 3 refs., 2 figs

Structural control on gold mineralization in the Satulinmäki and Riukka prospects, Häme Schist Belt, southern Finland

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Kerstin Saalmann

2007-01-01

Full Text Available The Satulinmäki and Riukka prospects located in the Häme Schist Belt in southern Finland are dominated by mafic and intermediate to felsic metavolcanic rocks of the Forssa Group formed in a continental arc setting. This magmatic belt formed some 1890–1880 Ma ago and has been deformed during the Svecofennian orogeny. The dominant penetrative foliation is represented by Sn+1, which is axial planar to cm- to dm-scale iscolinal Fn+1 folds and thus parallel to the layering Sn. Associated ductile shearing might reflect early thrusting. Dn+2 post-dating peak metamorphism is characterized by small-scale to regional-scale refolding of Fn+1 folds around ~SW-NE fold axes. This phase is transitional to development of SW-NE to WSW-ENE and NW-SE striking shear zones and faults formed due to dextral transpressionduring Dn+3 at retrograde conditions crossing the brittle-ductile transition. Many mineralized quartz veins have formed during this event. Later faults and quartz veins and reactivation of pre-existing structures during Dn+4 indicate rotation of the stress field to ~NESWoriented compression. A clear ~SW-NE trend of sulphide mineralization and elevated gold contents and the spatial association to Dn+3 quartz veins, shear zones and faults suggest a strong structural control, typical of orogenic gold deposits, and that mineralization took place during Dn+3. The controlling structures, (i WSW-ENE to SW-NE shear zones and faults and (ii NW-SE oriented fault, are second and third order structures to major regional-scale shear zones. The fault zones and their intersection points impart a directional permeability so that the mineralising fluids were channelled along dilatant zones. Approximately (WNW-(ESE trending faults being (reactivated as extensional faults or dilatant shear planes during Dn+3 transpression with WNW-ESE to NW-SE oriented compression direction could have acted as conduits for fluids during upward flow from deeper crustal level. Future

Adsorption effectiveness of β-lactoglobulin onto gold surface determined by quartz crystal microbalance.

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Jachimska, B; Świątek, S; Loch, J I; Lewiński, K; Luxbacher, T

2018-06-01

Bovine β-lactoglobulin (LGB) is a transport protein that can bind to its structure hydrophobic bioactive molecules. Due to the lack of toxicity, high stability and pH-dependent molecular binding mechanism, lactoglobulin can be used as a carrier of sparingly soluble drugs. Dynamic light scattering has confirmed LGB's tendency to create oligomeric forms. The hydrodynamic diameter of LGB molecules varies from 4 nm to 6 nm in the pH range of 2-10 and ionic strength I = 0.001-0.15 M, which corresponds to the presence of mono or dimeric LGB forms. The LGB zeta potential varies from 26.5 mV to -33.3 mV for I = 0.01 M and from 13.3 mV to -16 mV for I = 0.15 M in the pH range of 2-10. The isoelectric point is at pH 4.8. As a result of strong surface charge compensation, the maximum effective ionization degree of the LGB molecule is 35% for ionic strength I = 0.01 M and 22% for I = 0.15 M. The effectiveness of adsorption is linked with the properties of the protein, as well as those of the adsorption surface. The functionalization of gold surfaces with β-lactoglobulin (LGB) was studied using a quartz crystal microbalance with energy dissipation monitoring (QCM-D). The effectiveness of LGB adsorption correlates strongly with a charge of gold surface and the zeta potential of the molecule. The greatest value of the adsorbed mass was observed in the pH range in which LGB has a positive zeta potential values, below pH 4.8. This observation shows that electrostatic interactions play a dominant role in LGB adsorption on gold surfaces. Based on the adsorbed mass, protein orientation on gold surfaces was determined. The preferential side-on orientation of LGB molecules observed in the adsorption layer is consistent with the direction of the molecule dipole momentum determined by molecular dynamics simulations of the protein (MD). The use of the QCM-D method also allowed us to determine the effectiveness of adsorption of LGB on gold

[Characteristics of Raman spectra of minerals in the veins of Wenchuan earthquake fault zone].

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Xie, Chao; Zhou, Ben-gang; Liu, Lei; Zhou, Xiao-cheng; Yi, Li; Chen, Zhi; Cui, Yue-ju; Li, Jing; Chen, Zheng-wei; Du, Jian-guo

2015-01-01

Quartz in the veins at the Shenxigou section of Wenchuan earthquake fault zone was investigated by micro-Raman spectroscopic measurement, and the distribution of compressive stress in the fault zone was estimated by the frequency shifts of the 464 cm-1 vibrational mode of quartz grains in the veins. It was showed that the 464 cm-1 peak arising from the quartz grains in the veins near the fault plane shifts by 3. 29 cm-1 , and the corresponding compressive stress is 368. 63 MPa, which is significantly lower than the stress accumulation on both sides due to multi-stage events. Stress accumulation increased with moving away from the fault plane in the footwall with the offset of the 464 cm-1 peak arising from the quartz grains in the veins increasing, which can reach 494. 77 MPa at a distance of 21 m with a high offset of 4. 40 cm-1 of the 464 cm-1 peak. The compressive stress gets the maximum value of 519.87 MPa at a distance of 10 m from the fault plane in the hanging wall with the offset of the 464 cm-1 peak arising from the quartz grains in the veins being 4. 62 cm-1, followed by a sudden drop in stress accumulation, and it drops to 359. 59 MPa at a distance of 17 m. Because of moving away from the foult plane at the edge of the foult zone, the stress drops to 359. 59 MPa with a small value of 464 cm-1 peak offset 3. 21 cm-1 at a distance of 27 m from the fault plane in the hanging wall due to the little effect by the fault activity. Therefore, the stress of Wenchuan earthquake fault zone is partially released, but the rest of the stress distribution is uneven, and there is also a high stress accumulation in somewhere in the fault zone, which reflects that the mechanical properties of the rocks in the fault zone have a characteristic of unevenness in space.

Geology of the epithermal Ag-Au Huevos Verdes vein system and San José district, Deseado massif, Patagonia, Argentina

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Dietrich, Andreas; Gutierrez, Ronald; Nelson, Eric P.; Layer, Paul W.

2012-03-01

The San José district is located in the northwest part of the Deseado massif and hosts a number of epithermal Ag-Au quartz veins of intermediate sulfidation style, including the Huevos Verdes vein system. Veins are hosted by andesitic rocks of the Bajo Pobre Formation and locally by rhyodacitic pyroclastic rocks of the Chon Aike Formation. New 40Ar/39Ar constraints on the age of host rocks and mineralization define Late Jurassic ages of 151.3 ± 0.7 Ma to 144.7 ± 0.1 Ma for volcanic rocks of the Bajo Pobre Formation and of 147.6 ± 1.1 Ma for the Chon Aike Formation. Illite ages of the Huevos Verdes vein system of 140.8 ± 0.2 and 140.5 ± 0.3 Ma are 4 m.y. younger than the volcanic host rock unit. These age dates are among the youngest reported for Jurassic volcanism in the Deseado massif and correlate well with the regional context of magmatic and hydrothermal activity. The Huevos Verdes vein system has a strike length of 2,000 m, with several ore shoots along strike. The vein consists of a pre-ore stage and three main ore stages. Early barren quartz and chalcedony are followed by a mottled quartz stage of coarse saccharoidal quartz with irregular streaks and discontinuous bands of sulfide-rich material. The banded quartz-sulfide stage consists of sulfide-rich bands alternating with bands of quartz and bands of chlorite ± illite. Late-stage sulfide-rich veinlets are associated with kaolinite gangue. Ore minerals are argentite and electrum, together with pyrite, sphalerite, galena, chalcopyrite, minor bornite, covellite, and ruby silver. Wall rock alteration is characterized by narrow (propylitic alteration. Gangue minerals are dominantly massive quartz intergrown with minor to accessory adularia. Epidote, illite, illite/smectite, and, preferentially at deeper levels, Fe-chlorite gangue indicate near-neutral pH hydrothermal fluids at temperatures of >220°C. Kaolinite occurring with the late sulfide-rich veinlet stage indicates pH 315°, whereas strike

Oxygen isotope zonation at the Golden Cross low-sulfidation epithermal gold deposit, New Zealand

International Nuclear Information System (INIS)

Mauk, J.L.; Simpson, M.P.

2001-01-01

Forty-one whole rock samples from the Gold Cross low-sulfidation epithermal Au-Ag deposit have δ 18 O values that range from 4.4 to 9.3 per mil, with an average value of 7.0 per mil. Unaltered and weakly altered rocks have δ 18 O values greater than 8 per mil, and the orebody is surrounded by samples that are depleted in 18 O. A strongly silicified sample adjacent to the Empire Vein System has a δ 18 O value of 9.0 per mil, similar to previously reported analyses of vein quartz (7.0 to 11.7 per mil, average 9.4 per mil). This suggests that, in detail, Golden Cross may have a zone of 18 O-enriched wall rocks in the core of the deposit, adjacent to the main underground veins. Although some workers have suggested that stable isotope geochemistry may provide useful information for epithermal mineral deposit exploration, at Golden Cross this is not the case. Alteration minerals, major elements and trace elements all define larger, less ambiguous halos than the zone of 18 O-depleted wall rocks. (author). 21 refs., 3 figs., 1 tab

Gold deposits in the Xiaoqinling-Xiong'ershan region, Qinling mountains, central China

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Mao, J.; Goldfarb, R.J.; Zhang, Z.; Xu, W.; Qiu, Yumin; Deng, J.

2002-01-01

The gold-rich Xiaoqinling-Xiong'ershan region in eastern Shaanxi and western Henan provinces, central China, lies about 30-50 km inland of the southern margin of the North China craton. More than 100 gold deposits and occurrences are concentrated in the Xiaoqinling (west), Xiaoshan (middle), and Xiong'ershan (east) areas. Late Archean gneiss of the Taihua Group, and Middle Proterozoic metavolcanic rocks of the Xiong'er Group are the main host rocks for the deposits. Mesozoic granitoids (ca. 178-104 Ma) are present in most gold districts, but deposits are typically hosted in the Precambrian basement rocks hundreds of meters to as far as 10 km from the intrusions and related hornfels zones. Deposits in the Xiaoqinling and Xiaoshan areas are best classified as orogenic gold deposits, with ores occurring in a number of distinct belts both in quartz veins and disseminated in altered metamorphic rocks. Alteration assemblages are dominated by quartz, sericite, pyrite, and carbonate minerals. The ore-forming fluids were low salinity, CO2-rich, and characterized by isotopically heavy ??18O. Four deposits (Dongchuang, Wenyu, Yangzhaiyu, and Dahu) in the Xiaoqinling area each contain resources of about 1 Moz Au. Some of the gold deposits in the Xiong'ershan area represent more shallowly emplaced tellurium-enriched orogenic systems, which include resources of approximately 1-1.5 Moz Au at Shanggong and Beiling (or Tantou). Others are epithermal deposits (e.g., Qiyugou and Dianfang) that are hosted in volcanic breccia pipes. Isotopic dates for all gold deposits, although often contradictory, generally cluster between 172-99 Ma and are coeval with emplacement of the post-kinematic granitoids. The gold deposits formed during a period of relaxation of far-field compressional stresses, clearly subsequent to the extensive Paleozoic-early Mesozoic accretion of are terranes and the Yangtze craton onto the southern margin of the North China craton. Hydrothermal and magmatic events

Distribution and composition of gold in porphyry gold systems: example from the Biely Vrch deposit, Slovakia

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Koděra, Peter; Kozák, Jaroslav; Brčeková, Jana; Chovan, Martin; Lexa, Jaroslav; Jánošík, Michal; Biroň, Adrián; Uhlík, Peter; Bakos, František

2018-03-01

The Biely Vrch deposit in the Western Carpathians is assigned to the shallow, sulfide-poor porphyry gold deposit type and has an exceptionally low Cu/Au ratio. According to 3-D geochemical models, there is a limited spatial correlation between Au and Cu due to the primary introduction of gold by a salt melt and Cu by low-density vapor. Despite a rough spatial correlation of gold grades with quartz stockwork intensity, gold is hosted mostly by altered rock, exclusively in native form. Three main gold mineral assemblages were recognized here. In the deepest parts of the system, the K- and Ca-Na silicate gold assemblage is associated with minerals of high-temperature alteration (plagioclase, K-feldspar, actinolite), with gold grades and fineness depending on depth and potassium content of the host rock: K-silicate alteration hosts the lowest fineness gold ( 914), whereas Ca-Na silicate alteration has the highest ( 983). The intermediate argillic gold assemblage is the most widespread, with gold hosted mainly by chlorite, illite, smectite, and interstratified illite-chlorite-smectite minerals. The gold fineness is mostly variable (875-990) and inherited from the former gold mineral assemblages. The latest advanced argillic gold assemblage has its gold mostly in kaolinite. The extremely high fineness ( 994) results from gold remobilization by late-stage aqueous magmatic-hydrothermal fluids. Uncommon bonanza-grade appears where the earlier gold mineral assemblages were further enriched by this remobilized gold. Primary precipitation of gold occurred during ascent and cooling of salt melts at 450 to 309 °C, mostly during retrograde quartz solubility.

Dating quartz: Ar/Ar analyses of coexisting muscovite and fluid inclusion - rich quartz from paleocene amorphic aureole

International Nuclear Information System (INIS)

Matthews, S.J.; Perez de Arce, C.; Cornejo, P.; Cuitino, L; Klein, J

2001-01-01

We present Ar/Ar total fusion and step-heating data for coexisting muscovite and white quartz from the metamorphic aureole of the Lower Paleocene La Copiapina Pluton, 6 km south of Inca de Oro, III Region, Chile. The pluton intrudes the upper clastic sedimentary member of the Punta del Cobre Group (Upper Jurassic - Lower Cretaceous) and the calcareous sedimentary rocks of the Chanarcillo Group (Neocomian), and comprises fine to coarse grained pyroxene-hornblende-biotite quartz diorites and monzodiorites. Its emplacement was controlled on its north-western side by a subvertical NE-trending fault, along which were developed vertically banded skarns (skarn mylonite), suggesting syntectonic intrusion. Biotite K-Ar ages for the pluton fall in the range 61-63 Ma, relating it to a latest Cretaceous to Lowest Paleocene syn-compressional intrusive belt which is present in the area (Matthews and Cornejo, 2000). A metamorphic / metasomatic aureole is developed within the sandstones of the Punta del Cobre Group, on the extreme northern limit of the pluton. In this area, the sedimentary rocks have been replaced by quartz-sericite and quartz-muscovite assemblages, with minor hematite and tourmaline, and late supergene kaolinite and pyrophyllite. A coarse muscovite-quartz-tourmaline-hematite assemblage is developed in and around older (early Upper Cretaceous) andesitic dykes, in the form of replacement / fracture fill veins and replacement zones. Further from the contact with the pluton, fine-grained quartz-sericite rock with coarser muscovite-rich replacement veins represents the dominant lithology. Quartz in the coarse replacement rock is very rich in fluid inclusions. Primary inclusions are mainly of two coexisting types; bi-phase (liquid and gas bubble) and tri-phase (liquid, gas bubble and halite crystal), indicating that the quartz formed in the presence of a boiling fluid. Some inclusions also contain sylvite and occasional hematite daughter crystals. Secondary inclusions

Fluid Inclusion Study of The Tumpangpitu High Sulfidation Epithermal Gold Deposit in Banyuwangi District, East Java, Indonesia

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Yu Yu Myaing

2018-03-01

Full Text Available The Tumpangpitu high sulfidation (HS epithermal gold deposit is located in the south coast of East Java, Banyuwangi District, East Java Province, Indonesia. This area lies within the central portion of the Cenozoic Sunda‐Banda magmatic arc which trends southeast from northern Sumatra to west Java then eastward through east Java, Bali, Lombok, Sumbawa and terminating at Banda sea. The geology of the Tumpangpitu is predominantly occupied by Late Oligocene to Middle Miocene low-K calc-alkaline to alkaline andesitic volcanic rocks and interbedded with volcaniclastic rock sequences, which are associated with low-K intermediate intrusions. The mineralization style at the Tumpangpitu area is composed of a high‐sulfidation (HS epithermal gold-copper system which is typically associated with concealed gold-rich porphyry copper system. The HS epithermal mineralization is hosted by volcanic and volcaniclastic rocks in this research area. The mineralization domains are divided into Zone A, Zone B and Zone C which are situated along NW-SE-trending silica ledges zones. The HS epithermal mineralization is texturally occurs as vuggy replacements mineralization as well as stockworks, disseminated forms, fractures and veins. Fluid inclusion study was conducted for 6 quartz vein samples which petrographically entrapped fluid inclusions. Homogenization temperature (Th and melting temperature (Tm can microthermometrically be determined by fluid inclusion analysis. The average homogenization temperature (Th of the fluid inclusions gives 180˚C to 342˚C and melting temperature are from -0.1 ˚C to -1.4˚C. Tm corresponds to the salinities ranging from 0.1 to 4.5 wt% NaCl equivalent. The paleodepth of ore formation can be estimated from the salinity of fluid. Since the deposit was not formed at boiling condition, the minimum paleodepth of ore (quartz samples taken from both shallow level (53.35 m and deep level (135.15 m is determined at 650m and 1,220 m

Application of kinematic vorticity and gold mineralization for the wall rock alterations of shear zone at Dungash gold mining, Central Eastern Desert, Egypt

Science.gov (United States)

Kassem, Osama M. K.; Abd El Rahim, Said H.; El Nashar, EL Said R.; AL Kahtany, Kaled M.

2016-11-01

The use of porphyroclasts rotating in a flowing matrix to estimate mean kinematic vorticity number (Wm) is important for quantifying the relative contributions of pure and simple shear in wall rocks alterations of shear zone at Dungash gold mine. Furthermore, it shows the relationship between the gold mineralization and deformation and also detects the orientation of rigid objects during progressive deformation. The Dungash gold mine area is situated in an EW-trending quartz vein along a shear zone in metavolcanic and metasedimentary host rocks in the Eastern Desert of Egypt. These rocks are associated with the major geologic structures which are attributed to various deformational stages of the Neoproterozoic basement rocks. We conclude that finite strain in the deformed rocks is of the same order of magnitude for all units of metavolcano-sedimentary rocks. The kinematic vorticity number for the metavolcanic and metasedimentary samples in the Dungash area range from 0.80 to 0.92, and together with the strain data suggest deviations from simple shear. It is concluded that nappe stacking occurred early during the underthrusting event probably by brittle imbrication and that ductile strain was superimposed on the nappe structure during thrusting. Furthermore, we conclude that disseminated mineralization, chloritization, carbonatization and silicification of the wall rocks are associated with fluids migrating along shearing, fracturing and foliation of the metamorphosed wall rocks.

Characterization of color centers in quartz induced by gamma irradiation

International Nuclear Information System (INIS)

Guttler, Rainer A.S.

2009-01-01

The availability of gamma ray irradiators in Brazil increased the possibilities of treatments of gemstones for color enhancements. One of the minerals with a very high potential of these treatments is quartz, a very widespread mineral with much colored commercial varieties. Quartz occurs in Brazil mainly in two geological environments, called pegmatitic and hydrothermal. The detailed mechanism of color center formation of these two types of quartz will be investigated by spectroscopic and chemical analysis. Until yet, it can be shown that due to chemical differences of the nature of mineral forming fluids, the two types behave differently. All quartzes contain mainly traces of Iron, Aluminum, Lithium and some amounts of Water. The quartz of hydrothermal origin incorporated much structurally bound water, and despite some similarities with the chemical composition of pegmatitic quartz, this high water content is the reason for the formation of Silanol radicals, giving the green color to the quartz. The main difference in chemical composition of pegmatitic quartz is the presence of higher amounts of Al and Li , responsible for the brownish and yellowish colors formed by irradiation. Since each pegmatite is different, the quartz will behave differently. This explains the formation of the famous 'Green Gold' of quartz from Sao Jose da Safira , and the more yellowish, Citrine type, color of quartz from the Coluna deposit, near Itamarandiba, Minas Gerais. (author)

Characterization of color centers in quartz induced by gamma irradiation

Energy Technology Data Exchange (ETDEWEB)

Guttler, Rainer A.S., E-mail: rainersg@usp.b [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias; Enokihara, Cyro T.; Rela, Paulo R., E-mail: prela@ipen.b, E-mail: cteiti@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2009-07-01

The availability of gamma ray irradiators in Brazil increased the possibilities of treatments of gemstones for color enhancements. One of the minerals with a very high potential of these treatments is quartz, a very widespread mineral with much colored commercial varieties. Quartz occurs in Brazil mainly in two geological environments, called pegmatitic and hydrothermal. The detailed mechanism of color center formation of these two types of quartz will be investigated by spectroscopic and chemical analysis. Until yet, it can be shown that due to chemical differences of the nature of mineral forming fluids, the two types behave differently. All quartzes contain mainly traces of Iron, Aluminum, Lithium and some amounts of Water. The quartz of hydrothermal origin incorporated much structurally bound water, and despite some similarities with the chemical composition of pegmatitic quartz, this high water content is the reason for the formation of Silanol radicals, giving the green color to the quartz. The main difference in chemical composition of pegmatitic quartz is the presence of higher amounts of Al and Li , responsible for the brownish and yellowish colors formed by irradiation. Since each pegmatite is different, the quartz will behave differently. This explains the formation of the famous 'Green Gold' of quartz from Sao Jose da Safira , and the more yellowish, Citrine type, color of quartz from the Coluna deposit, near Itamarandiba, Minas Gerais. (author)

Uraniferous quartz-pebble conglomerates in South Africa

International Nuclear Information System (INIS)

von Backstroem, J.W.

1981-01-01

The purpose of this paper is to give a short background statement summarizing data on the Dominion Reef Group, the Witwatersrand Supergroup, and the Ventersdorp Contact Reef, with particular reference to the close relationship of gold and uranium with sedimentary features as well as the mineralization, conditions of deposition, and the nature of the quartz-pebble conglomerates

Update of endovenous treatment modalities for insufficient saphenous veins-A review of literature

NARCIS (Netherlands)

van Eekeren, Ramon R. J. P.; Boersma, Doeke; de Vries, Jean-Paul P. M.; Zeebregts, Clark J.; Reijnen, Michel M. P. J.

Lower-limb venous insufficiency resulting from saphenous vein incompetence is a common disorder, increasing with age. For decades, surgical stripping of the great saphenous vein has been the gold standard in varicose vein treatment. The desire to optimize outcomes of treatment and reduce surgical

Gold-bearing hydrothermal veins in Chukotka

Energy Technology Data Exchange (ETDEWEB)

Davidenko, N.M.

1980-01-01

Indicators such as the correlation of mineralization to plutonic and vulcanic formations and various facies of metamorphism, the character of the structural-tectonic control of mineralization, characteristics of silica redistribution as well that of calcium, water, and other components in altering ore zones, the specificity of sygenetic fluid inclusions in minerals, morphology, the internal structure and other typomorphic indicators of native gold and its accessories are utilized in the working out of a genetic classification for compiling a complex of diagnostic indicators of post-magmatic mineralization on Chukotka at various depths. Those indicators, in addition to earlier known hydrothermal gold ore formations, can be used to identify still other types of mineralization, particularly pyrite group minerals.

Evolution of the Bucium Rodu and Frasin magmatic-hydrothermal system, Metaliferi Mountains, Romania

Science.gov (United States)

Iatan, Elena Luisa; Berbeleac, Ion; Visan, Madalina; Minut, Adrian; Nadasan, Laurentiu

2013-04-01

The Miocene Bucium Rodu and Frasin maar-diatreme structures and related Au-Ag epithermal low sulfidation with passing to mesothermal mineralizations are located in the Bucium-Rosia Montana-Baia de Aries metallogenetic district, within so called the "Golden Quatrilaterum", in the northeastern part of the Metaliferi Mountains. These structures are situated at about 5 km southeast from Rosia Montana, the largest European Au-Ag deposit. The total reserves for Bucium Rodu-Frasin are estimated at 43.3 Mt with average contents of 1.3 g/t Au and 3 g/t Ag. The Miocene geological evolution of Bucium Rodu and Frasin magmatic-hydrothermal system took place in closely relationships with tectonic, magmatic and metallogenetic activity from Bucium-Rosia Montana-Baia de Aries district in general, and adjacent areas, in special. The hydrothermal alteration is pervasive; adularia followed by phyllic, carbonatization and silicification alterations, usually show a close relationship with the mineralizations. Propylitic alteration occurs dominantly towards the depth; argillic alteration shows a local character. The mineralization occurs in veins, breccias, stockworks and disseminations and is hosted within two volcanic structures emplaced into a sequence of Cretaceous sediments in closely genetically relations with the Miocene phreatomagmatic fracturing and brecciation events. Within Rodu maar-diatreme structure the mineralizations follow especially the contact between the diatreme and Cretaceous flysch. The vein sets with low, moderately and near vertical dippings, cover 400x400m with N-S trend. The most important mineralization style is represented by veins, accompanied by hydrothermal breccias and disseminations. The veins spatial distribution relives as "en echelon" tension veins. They carry gold, minor base metal sulphides (pyrite, chalcopyrite, sphalerite, galena, tetrahedrite, arsenopyrite). Gangue is represented by carbonates (calcite, dolomite, ankerite, siderite, rhodochrosite

Indikasi mineralisasi epitermal emas bersulfi da rendah, di Wilayah Kecamatan Bonjol, Kabupaten Pasaman, Sumatera Barat

Directory of Open Access Journals (Sweden)

Hamdan Z. Abidin

2014-06-01

Full Text Available http://dx.doi.org/10.17014/ijog.vol2no1.20075Bonjol gold prospect, known as Old Dutch Gold mine, consists of several ore bodies (Malintang, Balimbing, Lubang Sempit, Lubang Belanda and Lubang Perak. The deposit hosts within the altered volcanic rocks known as Gunung Amas Formation of Early Miocene age (9.3 ± 0.4 - 11.9 ±1.0 Ma. This formation consists of various rock types such as rhyolitic tuff, volcanic breccia, dacitic tuffs and rhyolites. These rocks are moderate to strongly alter. Mineralogy of the deposit consists of gold and silver with minor pyrite, sphalerite and galena. Besides this, hematite, jarosite and manganese are also present as supergene minerals. Ore minerals are found within quartz veins ranging from few centimetres to tens of metres thick. The veins are characterized by crustiform, comb, vuggy, botroyidal, layering and bladed. Quartz is a dominant mineral as hydrothermal alteration in addition to illite, dickite, monmorillonite, kaolinite, chlorite, smectite, natrolite, nontronite, calcite, halloysite, palygorskite, muscovite, sepiolite, analcime, heulandite, clino-chlor, zircon, zoisite, laumontite, alunite, biotite and erionite. The presence of these secondary minerals could be classifi ed into prophylitic, argillic and advanced argillic types. Analytical result of gold–bearing quartz vein indicates higher content of gold (0.3% and silver (400 ppm. In contrast, the content of sulphide minerals (Cu, Pb, and Zn is very low (< 100 ppm. Combined geology, mineralogy, textures and alteration minerals, it is concluded that gold deposit in the area shows an indication of a low sulphidation epithermal type within Gunung Amas Formation.  

Hydrothermal Gold Mineralization and Structural Controls near May ...

African Journals Online (AJOL)

Mickiale

controlled gold mineralized zones of gold near Workamba. .... consists of rounded to sub-rounded clasts of blue quartz eyes and varies in size from ... Based on the field observation, petrographic study and their cross cutting relationships; four.

40Ar/39Ar constraints on the timing and history of amphibolite facies gold mineralisation in the Southern Cross area, Western Australia

International Nuclear Information System (INIS)

Napier, R.W.; Guise, P.G.; Rex, D.C.

1998-01-01

The Southern Cross Greenstone Belt in Western Australia contains structurally controlled, hydrothermal gold deposits which are thought to have formed at or near the peak of amphibolite facies regional metamorphism during the Late Archaean. Although the geological features of deposits in the area are well documented. conflicting genetic models and ore-fluid sources have been used to explain the observed geological data. This paper presents new 40 Ar/ 39 Ar data which suggest that the thermal history of the Southern Cross area after the peak of regional metamorphism was more complex than has previously been suggested. After the main gold mineralisation event prior to ca 2620 Ma, the 40 Ar/ 39 Ar ages from amphiboles and biotites sampled from the alteration selvages of gold-bearing veins indicate that temperatures remained elevated in the region of 500 deg C for between 20 and 70 million years. These amphiboles and biotites from individual deposits yield ages that are in good agreement with one another to a high precision. implying increased cooling rates after the long period of elevated temperatures. Along the Southern Cross Greenstone Belt. however. amphibole-biotite pairs from the alteration selvages of gold-bearing quartz veins. while remaining in good agreement with one another, vary between deposits from ca 2560 Ma to ca 2440 Ma. Amphiboles from metabasalts that are associated with regional metamorphism and not hydrothermal alteration contain numerous exsolution lamellae that reduce the effective closure temperature of the amphiboles and yield geologically meaningless ages. These age relationships show that the thermal history of the area did not follow a simple cooling path and the area may have been tectonically active for a long period after the main gold mineralisation event before ca 2620 Ma. Such data may provide important constraints on subsequent genetic modelling of gold mineralisation and metamorphism. Copyright (1998) Blackwell Science Asia

Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Chemical controls on alteration and mineralization

Science.gov (United States)

Henley, R.W.; Berger, B.R.

2011-01-01

Large bulk-tonnage high-sulfidation gold deposits, such as Yanacocha, Peru, are the surface expression of structurally-controlled lode gold deposits, such as El Indio, Chile. Both formed in active andesite-dacite volcanic terranes. Fluid inclusion, stable isotope and geologic data show that lode deposits formed within 1500. m of the paleo-surface as a consequence of the expansion of low-salinity, low-density magmatic vapor with very limited, if any, groundwater mixing. They are characterized by an initial 'Sulfate' Stage of advanced argillic wallrock alteration ?? alunite commonly with intense silicification followed by a 'Sulfide' Stage - a succession of discrete sulfide-sulfosalt veins that may be ore grade in gold and silver. Fluid inclusions in quartz formed during wallrock alteration have homogenization temperatures between 100 and over 500 ??C and preserve a record of a vapor-rich environment. Recent data for El Indio and similar deposits show that at the commencement of the Sulfide Stage, 'condensation' of Cu-As-S sulfosalt melts with trace concentrations of Sb, Te, Bi, Ag and Au occurred at > 600 ??C following pyrite deposition. Euhedral quartz crystals were simultaneously deposited from the vapor phase during crystallization of the vapor-saturated melt occurs to Fe-tennantite with progressive non-equilibrium fractionation of heavy metals between melt-vapor and solid. Vugs containing a range of sulfides, sulfosalts and gold record the changing composition of the vapor. Published fluid inclusion and mineralogical data are reviewed in the context of geological relationships to establish boundary conditions through which to trace the expansion of magmatic vapor from source to surface and consequent alteration and mineralization. Initially heat loss from the vapor is high resulting in the formation of acid condensate permeating through the wallrock. This Sulfate Stage alteration effectively isolates the expansion of magmatic vapor in subsurface fracture arrays

Hydrothermal uranium vein deposits in Marysvale volcanic field, Utah

International Nuclear Information System (INIS)

Rasmussen, J.D.; Cunningham, C.G.; Steven, T.A.; Rye, R.O.; Romberger, S.B.

1984-01-01

Hydrothermal uranium veins are exposed over a 300 m (980 ft) vertical range in mines of the Central Mining area, near Marysvale, Utah. They cut 23 Ma quartz monzonite, 21 Ma granite, and 19 Ma rhyolite ash-flow tuff. The veins formed 18-19 Ma, in an area 1 km (0.6 mi) across, above the center of a composite magma chamber at least 12 x 6 km across that fed a sequence of 21-14 Ma hypabyssal granitic stocks, and rhyolitic lava flows, ash-flow tuffs, and volcanic domes. Intrusive pressure uplifted and fractured the roof; molybdenite-bearing, uranium-rich glassy dikes were intruded; and a breccia pipe and uranium-bearing veins were formed. The veins appear to have been deposited near the surface above a concealed rhyolite stock, where they filled high-angle fault zones and flat-lying to concave-downward pull-apart fractures. Low pH and fO 2 hydrothermal fluids at temperatures near 200 0 C (392 0 F) permeated the fractured rocks; these fluids were rich in fluorine and potassium, and contained uranium as uranous-fluoride complexes. Fluid-wall rock interaction increased fluid pH, causing precipitation of uranium minerals. At the deepest exposed levels, wall rocks were altered to kaolinite and sericite, and uraninite, coffinite, jordisite, fluorite, molybdenite, quartz, and pyrite (with delta 34 S near zero per mil) were deposited. The fluids were progressively oxidized higher in the system; iron in the wall rocks was oxidized to hematite, and sooty uraninite and umohoite were deposited

Transcutaneous laser treatment of leg veins

NARCIS (Netherlands)

Meesters, Arne A.; Pitassi, Luiza H. U.; Campos, Valeria; Wolkerstorfer, Albert; Dierickx, Christine C.

2014-01-01

Leg telangiectasias and reticular veins are a common complaint affecting more than 80% of the population to some extent. To date, the gold standard remains sclerotherapy for most patients. However, there may be some specific situations, where sclerotherapy is contraindicated such as needle phobia,

U-Th-Mo mineralisation in quartz syenite from Maturigiri-Dhurakantagiri, West Garo Hills District, Meghalaya, India

International Nuclear Information System (INIS)

Basu, A.N.; Sharma, G.S.; Varma, H.M.; Dhana Raju, R.; Dougall, N.K.; Raju, B.N.V.

1987-01-01

At Maturigiri and Dhurkantagiri, mineralised coarse-grained quartz syenite bodies (up to 10x2m) occur as intrusives along the NNW-SSE trending joints in the gneissic country rock. Mineralogically, the quartz syenite is characterised by over 50 per cent K-feldspar, lesser plagioclase, quartz, mica, garnet and chlorite, together with accessory uraninite, monazite, molybdenite and pyrite. Uraninite occurs as euhedral to subhedral inclusions and mineralisation is syngenetic. Two types of monazite, Th-poor and Th-rich, are present. Molybdenite occurs as veins along fractures and appears to be of late hydrothermal origin. The mineralogical and textural features suggest that quartz syenite was formed from a residual melt of granitic magma of crustal origin. (author). 7 refs., 9 figs

Gold in Accessory Zircon (the Kozhim Massif, Subpolar Urals)

Science.gov (United States)

Denisova, Yuliya; Pystin, Aleksandr

2017-12-01

The crystals of zircon due to their resistance to external impact of various processes can reveal information about the environment of their formation and the inclusions observed of them. Zircon contains different mineral inclusions: biotite, plagioclase, quartz, apatite, etc. However, there is no information about gold inclusions in the zircons from granites of the Sudpolar Urals. The study results of the inclusions of gold in accessory zircon of the Kozhim granitic massif are presented in this paper. The studied mineral is a dark-brown translucent short-prismatic crystal containing the inclusion of gold and the allocations of quartz. According to studies, the inclusion of gold formed during the growth of zircon and it is the gold covered with a thin film of oxide gold. It was confirmed that the crystallization of the studied zircon occurred at a temperature of 800°C and above on the stage of formation of granites of Kozhim massif. The assumption is made about the additional temperature in the course of which was caused by decreasing of temperature up to 700° C and below during postmagmatic stage.

Microscopy and Cathodoluminescence Spectroscopy Characterization of Quartz Exhibiting Different Alkali-Silica Reaction Potential.

Science.gov (United States)

Kuchařová, Aneta; Götze, Jens; Šachlová, Šárka; Pertold, Zdeněk; Přikryl, Richard

2016-02-01

Different quartz types from several localities in the Czech Republic and Sweden were examined by polarizing microscopy combined with cathodoluminescence (CL) microscopy, spectroscopy, and petrographic image analysis, and tested by use of an accelerated mortar bar test (following ASTM C1260). The highest alkali-silica reaction potential was indicated by very fine-grained chert, containing significant amounts of fine-grained to cryptocrystalline matrix. The chert exhibited a dark red CL emission band at ~640 nm with a low intensity. Fine-grained orthoquartzites, as well as fine-grained metamorphic vein quartz, separated from phyllite exhibited medium expansion values. The orthoquartzites showed various CL of quartz grains, from blue through violet, red, and brown. Two CL spectral bands at ~450 and ~630 nm, with various intensities, were detected. The quartz from phyllite displayed an inhomogeneous dark red CL with two CL spectral bands of low intensities at ~460 and ~640 nm. The massive coarse-grained pegmatite quartz from pegmatite was assessed to be nonreactive and displayed a typical short-lived blue CL (~480 nm). The higher reactivity of the fine-grained hydrothermal quartz may be connected with high concentrations of defect centers, and probably with amorphized micro-regions in the quartz, respectively; indicated by a yellow CL emission (~570 nm).

Au-bearing magnetite mineralizaion in Kashmar (alteration, mineralization, geochemistry, geochemistry and fluid inclusions;

Directory of Open Access Journals (Sweden)

Alireza Almasi

2017-02-01

fractures of rocks are filled with tourmaline (Dumortierite type and iron oxides. Kashmar surface mineralization is described in the ore-bearing quartz veins. Principal mineralization textures are layered, comb and Brecciation. The most important types of veins are those containing Chalcopyrite - Quartz veins, Specularite-rich veins – Quartz-Galena veins accompany with hydrothermal Breccias. Barren barite veins also exist in the region. The Chalcopyrite - Quartz veins occur on the main fracture zone and next to the Argillic alterations and silica cap in three regions (Bahariyeh, Uch Palang and Sarsefidal. Hydrothermal Breccias, Spicularite- rich veins, Quartz - Galena and barite veins occurred within Hematite- Carbonate-Chlorite-Silicification alterations in the Kamarmard area. Geochemistry of veins indicates anomalies of gold, copper, lead and zinc in them. Most enrichments of gold are accompanied with copper, lead and zinc and they occurs in hydrothermal Breccias and then specularite- rich veins. Gold values up to about 15 ppm and Cu, Pb and Zn each to > 1%. Temperature – salinity studies of fluid inclusions of ore-bearing Quartz veins in Kashmar show the fluid temperature and salinity values in all veins are close together. Temperatures are moderate to relatively high and between 245° C and 530 ° C and salinities are relatively low to moderate and between 14 to 18 (wt% NaCl. Maximum and minimum of temperatures and salinities are related to fluid inclusions of hydrothermal Breccias and Quartz-Galena vein. Co-existence between two-phase liquid-vapor rich fluids and single-phase gas fluids in the veins indicate that conditions were close to boiling, and maybe a little boiling occurred, which strengthened with brecciaing of rock and view rare CO2-bearing fluid inclusion in veins on the Kamarmard peak. Non-existence of vuggy Quartz in silica caps in the region shows this issue. The frequency of oxide minerals (Specularite, Barite, H2O-NaCl-CaCl2 system, and the low

Stratigraphy, tectonic and ore potential of pre-cambrian unities from Serro region-MG (Mato Grosso quadrangle)

International Nuclear Information System (INIS)

Assis, L.C. de.

1982-01-01

Geological and stratigraphic elements of the Proterozoic units of the Serro region, Mato Grosso Quadrangle, show the absence of the faciological transition between the Espinhaco Group and the Minas Supergroup. Occurs in this region is a lithostratigraphical sequence of four distinct units: the Crystalline Basement; the Volcano-Sedimentary Sequence of Serro; the Minas Supergroup. The ore potential of the region includes: quartz veins, within the Galho do Miguel Formation; diamond, within the Sopa conglomerates; gold, in alluvial deposits and remobilized in quartz veins of the Sopa-Brumadinho Formation; bauxite, in the metabasics; uranium in the metaconglomerates of Moeda Formation; iron, in Caue Formation; chromium, gold and base metals in the Volcano-Sedimentary Sequence of Serro. Emphasis is given to the characterization of the Volcano-Sedimentary Sequence of Serro and its mineralization that is characterized as a stratiform massif with important volcano-sedimentary contribution, possible, a greenstone belt, with high gold-bearing potential. (author)

Possible genetic link between I-type granite and orogenic gold deposits in Egypt (metamorphic-magmatic interaction?)

Science.gov (United States)

Abd El Monsef, Mohamed

2015-04-01

The orogenic gold deposits are a distinctive type of deposits that revealed unique temporal and spatial association with an orogeny. Where, the system of gold veins and related ore minerals was confined to hydrothermal solutions formed during compressional to transpressional deformation processes at convergent plate margins in accretionary and collisional orogens, with the respect to ongoing deep-crustal, subduction-related thermal processes. In Egypt, most of vein-type and dyke-type gold mineralization are restricted to granitic rocks or at least near of granitic intrusion that seems to have had an important influence on gold mineralization. Shear zone-related, mesothermal gold deposits of Fatira and Gidami mines in the northern Eastern Desert of Egypt are found within granitic bodies or at the contact between granites and metavolcanic rocks. The hosting-granitic rocks in Fatira and Gidami areas are mainly of granodioritic composition (I-Type granite) which is related to calc-alkaline magmatic series. However, Fatira granitoids were developed within island arc tectonic settings related to mature island arc system (Late-orogenic stage), at relatively low temperature (around 660° C) and medium pressure between (5 - 10 Kbar). On the other hand, Gidami granitoids were developed during the collision stage in continental arc regime related to active continental margin (Syn-orogeny), which were crystallized at relatively high temperature (700-720° C) and low pressure (around 0.1 Kbar). The ore mineralogy includes pyrite, chalcopyrite, sphalerite, covellite, ilmenite, goethite ± pyrrhotite ± pentlandite ± galena ± molybdenite. Native gold is detected only in Gidami mineralization as small inclusions within pyrite and goethite or as tiny grains scattered within quartz vein (in close proximity to the sulfides). In Fatira deposits, it is detected only by microprobe analysis within the crystal lattice of pyrite and jarosite. Fluid inclusions study for the mineralized

The La Unión Au ± Cu prospect, Camagüey District, Cuba: fluid inclusion and stable isotope evidence for ore-forming processes

Science.gov (United States)

Santana, Miriela María Ulloa; Moura, Márcia Abrahão; Olivo, Gema R.; Botelho, Nilson Francisquini; Kyser, T. Kurtis; Bühn, Bernhard

2011-01-01

The Camagüey district, Cuba, is known for its epithermal precious metal deposits in a Cretaceous volcanic arc setting. Recently, the La Unión prospect was discovered in the southern part of the district, containing gold and minor copper mineralization interpreted as porphyry type. Mineralization is hosted in a 73.0 ± 1.5 Ma calc-alkaline I-type oxidized porphyry quartz diorite intrusive within volcanic and volcaniclastic rocks of the early Cretaceous Guáimaro Formation. The porphyry is affected by propylitic alteration and crosscut by a network of quartz and carbonate veinlets and veins. Chlorite, epidote, sericite, quartz, and pyrite are the main minerals in the early veins which are cut by late carbonate and zeolite veins. Late barite pseudomorphously replaces pyrite. Gold is associated with pyrite as disseminations in the altered quartz diorite and in the veins, occurring as inclusions or filling fractures in pyrite with 4 g/t Au in bulk samples, and up to 900 ppm Au in in pyrite. Fluid inclusion and oxygen isotope data are consistent with a H2O-NaCl-(KCl) mineralizing fluid, derived from the quartz diorite magma, and trapped at least at 425°C and 1.2 kbar. This primary fluid unmixed into two fluid phases, a hypersaline aqueous fluid and a low-salinity vapor-rich fluid. Boiling during cooling may have played an important role in metal precipitation. Pyrite δ34S values for the La Unión prospect range between 0.71‰ and 1.31‰, consistent with a homogeneous magmatic sulfur source. The fluids in equilibrium with the mineralized rocks have estimated δ18O values from 8‰ to 11.8‰, calculated for a temperature range of 480-505°C. The tectonic environment of the La Unión prospect, its high gold and low copper contents, the physical-chemical characteristics of the mineralizing fluids and the isotopic signature of the alteration minerals and fluids indicate that the La Unión gold mineralization is similar to the porphyry gold type, even though the ore

Geology and hydrothermal alteration at the Madh adh Dhahab epithermal precious-metal deposit, Kingdom of Saudi Arabia

Science.gov (United States)

Doebrich, J.L.; LeAnderson, J.P.

1984-01-01

Mahd adh Dhahab is a late Precambrian epithermal gold-silver-base metal deposit located in the west-central part of the Arabian Shield. North-trending quartz veins containing base and precious metals cut an east-striking, north-dipping homoclinal sequence of volcanic, volcaniclastic, and epiclastic rocks of intermediate to felsic composition. Ore was localized where the veins cut competent, coarse-grained, fragmental units directly below incompetent and impermeable tuff units. The proximity of an epizonal rhyolite porphyry stock to these contacts also was important in localizing ore. Ore minerals include native gold and silver, gold-silver tellurides, chalcopyrite, sphalerite, and minor galena, and five stages of mineralization have been identified.

INTERFACE LAYER TO IMPROVE POLYSTYRENE ATTACHMENT ON A QUARTZ CRYSTAL RESONATOR

Directory of Open Access Journals (Sweden)

Doris Susana Llanes

Full Text Available Technologies for thin film deposition have been used to improve the functionalization of quartz crystal resonators (QCR; such technologies, for example, are spin coating and Langmuir-Blodgett (LB film preparation. These experiments are required because the film uniformity and homogeneity over the quartz crystal resonator are fundamental for its applications as chemical and biological sensors. Film deposition of polystyrene (PS particles, as well as polyvinyl chloride (PVC, was performed in solvents such as cyclohexanone, tetrahydrofuran (THF, dimethylformamide and chloroform at different concentrations using the spin coating procedure on wafer targets. The film quality was determined by optical microscopy, ellipsometry, and profilometry. Additionally, films on wafers or QCR with gold surface have been prepared by spreading the mentioned substances on an aqueous subphase and transferring it by dipping from the subphase surface onto the target. For LB film preparation arachidic acid and PS particles have been used. Prepared mono- or multilayered films of these substances on wafer or gold quartzes have been controlled additionally by IR-spectrometry. The resonant behavior of QCR before and after surface coating has been measured with a network analyzer. In combination with a graphical user interface the data could be easily recorded and visualized.

Probing Interfacial Friction and Dissipation in Granular Gold­ Nickel Alloys with a Quartz Crystal Oscillator in an External Magnetic Field

Science.gov (United States)

Stevens, K. M.; Krim, J.

2015-03-01

We present here a quartz crystal microbalance study of two-phase gold nickel alloys whose internal granular properties are probed by exposure to a fluctuating external magnetic field. The work is motivated by prior studies demonstrating that granular two-phase materials exhibited lower friction and wear than solid solution alloys with identical compositions. In particular, we report a ``flexing'' effect which appears when an external magnetic field is applied, and is manifested as a decrease in the magnitude of oscillation amplitude that is synchronized with the applied field; the effect is not seen on the complimentary solid solution samples. The effect is consistent with internal interfacial friction between nickel and gold grains, indicating a degree of freedom which may decrease friction even in the absence of an external magnetic field. This is supported through analysis of energy dissipation in the system, using the Butterworth­-Van Dyke equivalent circuit model. Data and interpretation are also presented that rule out alternate explanations such as giant magnetoresistance and/or other resistive phenomenon within the film. Funding provided by NSF DMR0805204. Thanks to L. Pan for sample preparation.

Sulphur isotopes in a metamorphogenic gold deposit, Macraes mine, Otago Schist, New Zealand

International Nuclear Information System (INIS)

Craw, D.; Hall, A.J.; Fallick, A.E.; Boyce, A.J.

1995-01-01

The Macraes gold quartz vein deposit, New Zealand, is located in a shear zone cutting greenschist facies metasediments of the Otago Schist. The deposit has been interpreted as being metamorphogenic in origin as there is no evidence for coeval magmatic activity in the Otago Schist orogen. The immediate host rock at the Macraes deposit is pyritic (δ 34 S = -2.7 to -1.3 per mil ) and locally weakly graphitic schist, a rare rock type in the Otago Schist. Sulphur isotope analyses of pyrite and arsenopyrite extracts from auriferous veins and wall-rock schist provide a similar narrow range in δ 34 S values, from -3.0 to -1.0 per mil (n=9). The lack of isotopically depleted sulphur, the narrow range in values, and the replacement sulphide textures help discount a primary bacteriogenic origin for host-rock sulphide. Sulphide in both veins and wall rock is of hydrothermal origin. Sulphides in metasediments and metavolcanics elsewhere in the Otago Schist have δ 34 S in the narrow range -6 to +6 per mil. The sulphur isotope data are consistent with origin of hydrothermal sulphur within the metamorphic pile but provide no constraint on specific rock types which contributed the sulphur to the hydrothermal fluid. The study demonstrates that sulphur isotopic signatures near zero per mil can arise without any direct magmatic input into the mineralisation process. (author). 34 refs., 2 figs., 1 tab

The late cretaceous Donlin Creek gold deposit, Southwestern Alaska: Controls on epizonal ore formation

Science.gov (United States)

Goldfarb, R.J.; Ayuso, R.; Miller, M.L.; Ebert, S.W.; Marsh, E.E.; Petsel, S.A.; Miller, L.D.; Bradley, D.; Johnson, Chad; McClelland, W.

2004-01-01

The Donlin Creek gold deposit, southwestern Alaska, has an indicated and inferred resource of approximately 25 million ounces (Moz) Au at a cutoff grade of 1.5 g/t. The ca. 70 Ma deposit is hosted in the Late Cretaceous Kuskokwim flysch basin, which developed in the back part of the are region of an active continental margin, on previously accreted oceanic terranes and continental fragments. A hypabyssal, mainly rhyolitic to rhyodacitic, and commonly porphyritic, 8- ?? 3-km dike complex, part of a regional ca. 77 to 58 Ma magmatic arc, formed a structurally competent host for the mineralization. This deposit is subdivided into about one dozen distinct prospects, most of which consist of dense quartz ?? carbonate veinlet networks that fill north-northeast-striking extensional fractures in the northeast-trending igneous rocks. The sulfide mineral assemblage is dominated by arsenopyrite, pyrite, and, typically younger, stibnite; gold is refractory within the arsenopyrite. Sericitization, carbonatization, and suffidation were the main alteration processes. Fluid inclusion studies of the quartz that hosts the resource indicate dominantly aqueous ore fluids with also about 3 to 7 mol percent CO2 ?? CH4 and a few tenths to a few mole percent NaCl + KCl. The gold-bearing fluids were mainly homogeneously trapped at approximately 275?? to 300??C and at depths of 1 to 2 km. Some of the younger stibnite may have been deposited by late-stage aqueous fluids at lower temperature. Measured ??18O values for the gold-bearing quartz range between 11 and 25 per mil; the estimated ??18O fluid values range from 7 to 12 per mil, suggesting a mainly crustally derived fluid. A broad range of measured ??D values for hydrothermal micas, between -150 and -80 per mil, is suggestive of a contribution from devolatilization of organic matter and/or minor amounts of mixing with meteoric fluids. Gold-associated hydrothermal sulfide minerals are characterized by ??34S values mainly between -16 and

Finite strain analysis of metavolcanics and metapyroclastics in gold-bearing shear zone of the Dungash area, Central Eastern Desert, Egypt

Science.gov (United States)

Kassem, Osama M. K.; Abd El Rahim, Said H.

2014-11-01

The Dungash gold mine area is situated in an EW-trending quartz vein along a shear zone in metavolcanic and metasedimentary host rocks in the Eastern Desert of Egypt. These rocks are associated with the major geologic structures, which are attributed to various deformational stages of the Neoproterozoic basement rocks. Field geology, finite strain and microstructural analyses were carried out and the relation-ships between the lithological contacts and major/minor structures have been studied. The R f/ϕ and Fry methods were applied on the metavolcano-sedimentary and metapyroclastic samples from 5 quartz veins samples, 7 metavolcanics samples, 3 metasedimentary samples and 4 metapyroclastic samples in Dungash area. Finite-strain data show that a low to moderate range of deformation of the metavolcano-sedimentary samples and axial ratios in the XZ section range from 1.70 to 4.80 for the R f/ϕ method and from 1.65 to 4.50 for the Fry method. We conclude that finite strain in the deformed rocks is of the same order of magnitude for all units of metavolcano-sedimentary rocks. Furthermore, the contact between principal rock units is sheared in the Dungash area under brittle to semi-ductile deformation conditions. In this case, the accumulated finite strain is associated with the deformation during thrusting to assemble nappe structure. It indicates that the sheared contacts have been formed during the accumulation of finite strain.

Three sets of crystallographic sub-planar structures in quartz formed by tectonic deformation

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Derez, Tine; Pennock, Gill; Drury, Martyn; Sintubin, Manuel

2016-05-01

In quartz, multiple sets of fine planar deformation microstructures that have specific crystallographic orientations parallel to planes with low Miller-Bravais indices are commonly considered as shock-induced planar deformation features (PDFs) diagnostic of shock metamorphism. Using polarized light microscopy, we demonstrate that up to three sets of tectonically induced sub-planar fine extinction bands (FEBs), sub-parallel to the basal, γ, ω, and π crystallographic planes, are common in vein quartz in low-grade tectonometamorphic settings. We conclude that the observation of multiple (2-3) sets of fine scale, closely spaced, crystallographically controlled, sub-planar microstructures is not sufficient to unambiguously distinguish PDFs from tectonic FEBs.

The gold nuggets of the lower Pliocene Alhambra Formation (Betic Cordillera, Southern Spain)

Science.gov (United States)

Somma, Roberta; Bonvegna, Piero; Sanchez-Navas, Antonio

2017-04-01

The present research was devoted to the geochemical and textural characterization of gold nuggets extracted from auriferous siliciclastic deposits of the lower Pliocene continental Alhambra Formation (Betic Cordillera, Southern Spain). This Formation is mainly composed of metamorphic lithoclasts deriving both by the erosion of the Mulhacen Unit of the Nevado-Filabride Complex and the reworking of the upper Tortonian marine Dudar-Pinos Genil Formation, on its turn previously formed by erosion of the Veleta Unit of the Nevado-Filabride Complex. Particularly, the studied gold nuggets were separated from 1m3 of auriferous conglomerates sampled along the right side of the Genil River, in the abandoned Lancha de Cenes Mine, exploited since Roman time for gold mining. The recovered gold nuggets were 24 for a total weight of 0.125 g/m3. Textural analysis of gold nuggets was made by means mechanical sieving and visual comparison of roundness and form. They are sand-sized rounded to sub-rounded grains with spheroidal and cubic form. Surface analyses of the nuggets by SEM-EDS indicated that external portions show textures more porous than in the nuggets nuclei. Chemical analyses by EMPA indicated that they are constituted by pure gold with Ag and Hg as trace elements. The gold mine capacity of the studied auriferous deposits is at least of 0.125 g/m3 (lower than 0.5 g/m3; minimum value to be gold mine economically exploitable). Notwithstanding this value, the auriferous conglomerates of the Alhambra Formation reveal to be interesting under a gold mine exploitation point of view because of the gold high pureness degree. Finally, under a geological point of view, considering that the Alhambra Formation is mainly composed of lower Pliocene alluvial fan conglomerates and sandstones formed during the uplift of the Sierra Nevada, the selected gold nuggets are secondary deposits originally derived from primary deposits related to hydrothermal gold-bearing quartz veins included in

Electroacoustic polymer microchip as an alternative to quartz crystal microbalance for biosensor development.

Science.gov (United States)

Gamby, Jean; Lazerges, Mathieu; Girault, Hubert H; Deslouis, Claude; Gabrielli, Claude; Perrot, Hubert; Tribollet, Bernard

2008-12-01

Laser photoablation of poly(ethylene terephthalate) (PET), a flexible dielectric organic polymer, was used to design an acoustic miniaturized DNA biosensor. The microchip device includes a 100-microm-thick PET layer, with two microband electrodes patterned in photoablated microchannels on one side and a depressed photoablated disk decorated by gold sputtered layer on the other side. Upon application of an electric signal between the two electrodes, an electroacoustic resonance phenomenon at approximately 30 MHz was established through the microelectrodes/PET/ gold layer interface. The electroacoustic resonance response was fitted with a series RLC motional arm in parallel with a static Co arm of a Buttlerworth-Van Dyke equivalent circuit: admittance spectra recorded after successive cycles of DNA hybridization on the gold surface showed reproducible changes on R, L, and C parameters. The same hybridizations runs were performed concomitantly on a 27-MHz (9 MHz, third overtone) quartz crystal microbalance in order to validate the PET device developed for bioanalysis applications. The electroacoustic PET device, approximately 100 times smaller than a microbalance quartz crystal, is interesting for the large-scale integration of acoustic sensors in biochips.

Tourmalines from the siderite-quartz-sulphide hydrothermal veins, Gemeric unit, western Carpathians, Slovakia: crystal chemistry and evolution

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Bačík, P.; Uher, P.; Dikej, J.; Puškelová, Ľ.

2018-02-01

Tourmaline is an important gangue mineral in a large number of Cretaceous siderite-quartz-sulphide hydrothermal veins in the Gemeric Unit, Slovak Ore Mountains, Slovakia, such as Dobšiná, Vlachovo, Rožňavské Bystré, Hnilčík, Rakovnica, Novoveská Huta, Gretla, Rudňany, and Bindt. In this study we combine by electron microprobe analysis, powder X-ray diffraction, Mössbauer and optical emission spectroscopy to determine the range of tourmaline compositions in the deposits and constrain the mechanisms of its precipitation. Selected samples from the mentioned deposits belong mostly to the alkali group, schorl to dravite series, rarely dominant X-site vacant foititic tourmaline (Vlachovo and Bindt) and oxy-dravite compositions (Hnilčík) were detected. Rim zones of some schorlitic tourmalines show high concentrations of Ti (up to 2.35 wt.% TiO2, 0.30 apfu; Rožňavské Bystré). The chemical composition is mostly controlled by alkali-deficient X □AlNa-1(Mg,Fe2+)-1 and proton-deficient AlO(Mg,Fe2+)-1(OH)-1 substitutions. Titanium is incorporated into the structure by Y Ti Y (Mg,Fe) Y Al-2, Y Ti Z Mg Y Al-1 Z Al-1, Y TiO( Y AlOH), and X Ca Y Ti Z MgO2 X □-1 Y,Z Al-2(OH)-2 substitutions. Along trace elements, Sr and V attain concentrations of 80-450 and 70-320 ppm, respectively. The unit-cell parameter a varies between 15.960 and 15.985 Å; variations in c are larger, between 7.177 and 7.236 Å indicating the presence of Fe3+ and Mg2+ at Z site. Mössbauer spectroscopy has shown variable Fe3+ proportions (0.17 -0.55 apfu) in all samples. The gathered dataset suggests some qualitative considerations on the mechanisms controlling tourmaline compositions at the regional scale. The highest Fe3+ concentrations occur in samples from Rudňany and Gretla in the external part of Gemeric unit, suggesting higher oxidation during longer transport of fluids. We propose that the determined XFe in the samples are correlated with the compositions of the host rocks, as

Application of U-Th-Pb phosphate geochronology to young orogenic gold deposits: New age constraints on the formation of the Grass Valley gold district, Sierra Foothills province, California

Science.gov (United States)

Taylor, Ryan D.; Goldfarb, Richard J.; Monecke, Thomas; Fletcher, Ian R.; Cosca, Michael A.; Kelly, Nigel M.

2015-01-01

The Grass Valley orogenic gold district in the Sierra Nevada foothills province, central California, the largest historic gold producer of the North American Cordillera, comprises both steeply dipping east-west (E-W) veins located along lithologic contacts in accreted ca. 300 and 200 Ma oceanic rocks and shallowly dipping north-south (N-S) veins hosted by the Grass Valley granodiorite; the latter have yielded about 70 percent of the 13 million ounces of historic lode gold production in the district. The oceanic host rocks were accreted to the western margin of North America between 200 and 170 Ma, metamorphosed to greenschist and amphibolite facies, and uplifted between 175 and 160 Ma. Large-scale magmatism in the Sierra Nevada occurred between 170-140 Ma and 120-80 Ma, with the Grass Valley granodiorite being emplaced during the older episode of magmatism. Uranium-lead isotopic dating of hydrothermal xenotime yielded the first absolute age of 162±5 Ma for the economically more significant N-S veins. The vein-hosted xenotime, as well as associated monazite, are unequivocally of hydrothermal origin as indicated by textural and chemical characteristics, including grain shape, lack of truncated growth banding, lack of a Eu anomaly, and low U and Th concentrations. Furthermore, the crack-seal texture of the veins, with abundant wallrock slivers, suggests their formation as a result of episodic fluid flow possibly related to reoccurring seismic events, rather than a period of fluid exsolution from an evolving magma. The N-S veins are temporally distinct from a younger 153-151 Ma gold event that was previously reported for the E-W veins. Overlapping U-Pb zircon (159.9±2.2 Ma) and 40Ar/39Ar biotite and hornblende (159.7±0.6 to 161.9±1.4 Ma) ages and geothermobarometric calculations indicate that the Grass Valley granodiorite was emplaced at ca. 160 Ma at elevated temperatures (~800°C) within approximately 3 km of the paleosurface and rapidly cooled to the ambient

Karakteristik mineralisasi epitermal di Daerah Taran, Hulu Kahayan, Kalimantan Tengah berdasarkan studi mikroskopis, X-Ray Diffraction (XRD, dan inklusi fluida

Directory of Open Access Journals (Sweden)

Danny Zulkifli Herman

2014-06-01

Full Text Available http://dx.doi.org/10.17014/ijog.vol1no3.20064Taran area is occupied predominantly by piroclastic rocks and locally intercalations of lenticular claystones and sandstones. The pyroclastic rocks are intruded by diorite, dacite and andesite, leading alteration and mineralization within the host rocks. Mineralization occurs as a vein type and is associated with a number of pervasive alteration types named respectively: quartz-illite- montmorillonite-kaolinite ± pyrite, quartz-illite ± pyrite, quartz-illite-chlorite ± pyrite and quartz- kaolinite-illite ± pyrite. On the other hand, a propylitic alteration also occurs within the andesite intrusion composed of calcite-epidote-chlorite-sericite-quartz ± pyrite. The mineralization is characterized by several zones of quartz stockwork containing gold and associated ore minerals of chalcopyrite, sphalerite, galena, pyrite and argentite. The quartz veins occurs as fi llings of structural openings in the form of milky quartz and amethyst with textures of sugary, comb, and dogteeth. Evaluation work on results of microscopic (petrography and mineragraphy, X-Ray Diffraction (XRD, and fl uid inclusion studies, and chemical analysis of entirely altered rock/quartz vein samples shows that the alteration and mineralization process were closely related to a change of hydrothermal fl uids, from near neutral into acid conditions at a temperature range of >290o – 100oC. The appearances of quartz variation indicate a relationship with repeated episodes of boiling in an epithermal system, as ground water mixed with hot vapor originated from a remained post-magmatic solution. Corresponding to a salinity of average 1,388 equiv.wt.% NaCl, it indicates that the ore minerals bearing quartz veins were deposited at a depth range of 640 – 1020 m beneath paleosurface.  

Petrology, chronology and sequence of vein systems: Systematic magmatic and hydrothermal history of a major intracontinental shear zone, Canadian Appalachians

Science.gov (United States)

Pe-Piper, Georgia; Piper, David J. W.; McFarlane, Chris R. M.; Sangster, Chris; Zhang, Yuanyuan; Boucher, Brandon

2018-04-01

Intra-continental shear zones developed during continental collision may experience prolonged magmatism and mineralization. The Cobequid Shear Zone formed part of a NE-SW-trending, orogen-parallel shear system in the late Devonian-early Carboniferous, where syn-tectonic granite-gabbro plutons and volcanic rocks 4 km thick were progressively deformed. In late Carboniferous to Permian, Alleghanian collision of Africa with Laurentia formed the E-W trending Minas Fault Zone, reactivating parts of the Cobequid Shear Zone. The 50 Ma history of hydrothermal mineralization following pluton emplacement is difficult to resolve from field relationships of veins, but SEM study of thin sections provides clear detail on the sequence of mineralization. The general paragenesis is: albite ± quartz ± chlorite ± monazite → biotite → calcite, allanite, pyrite → Fe-carbonates, Fe-oxides, minor sulfides, calcite and synchysite. Chronology was determined from literature reports and new U-Pb LA-ICPMS dating of monazite and allanite in veins. Vein mineralization was closely linked to magmatic events. Vein emplacement occurred preferentially during fault movement recognised from basin-margin inversion, as a result of fractures opening in the damage zone of master faults. The sequence of mineralization, from ca. 355 Ma riebeckite and albite veins to ca. 327 (-305?) Ma siderite-magnetite and sulfide mineralization, resembles Precambrian iron-oxide-copper-gold (IOCG) systems in the literature. The abundant magmatic Na, halogens and CO2 in veins and some magmatic bodies, characteristic of IOCG systems, were derived from the deeply subducted Rheic Ocean slab with little terrigenous sediment. Regional extension of the Magdalen Basin caused asthenospheric upwelling and melting of the previously metasomatized sub-continental lithospheric mantle. Crustal scale strike-slip faulting facilitated the rise of magmas, resulting in high heat flow driving an active hydrothermal system. Table S2

Geology and Isotope Systematics of the Jianchaling Au Deposit, Shaanxi Province, China: Implications for Mineral Genesis

Directory of Open Access Journals (Sweden)

Su-Wei Yue

2018-04-01

Full Text Available The giant Jianchaling Au (52 t Au deposit is located in the Mian-Lue-Yang Terrane in the southern part of the Qinling Orogen of central China and is hosted by metamorphosed carbonate rocks of the Late Neoproterozoic Duantouya Formation. The deposit consists of multiple generations of mineralised quartz(-carbonate veins in WNW-trending extensional ductile-brittle shear zones. Based on the mineral assemblages and cross-cutting relationships between the quartz(-carbonate veins, the paragenesis is characterised by an early coarse-grained pyrite-pyrrhotite-pentlandite-dolomite-quartz assemblage (I, followed by pyrite-sphalerite-galena-carbonate-arsenopyrite-fuchsite-carbonate-quartz containing gold (II, and fine-grained pyrite-dolomite-calcite-quartz-realgar (As2S2-orpiment (As2S3 (III. The H-O-C isotope systematics for the three vein sets indicate that the mineralising fluid is probably sourced from the metamorphic dehydration of carbonate rocks in the Duantouya Formation, and gradually mixed with meteoric water during the emplacement of the third vein set. The δ34S values for sulfides (6.3–16.6‰ from the second auriferous vein set are greater than zero, indicating sulfates reduction from the Neoproterozoic metamorphic rocks (Duantouya Fm. The (206Pb/204Pbi ratios from pyrite (17.521–18.477 from each of the vein sets overlap those of the ultramafic rocks (18.324–18.717 and the Bikou Group (17.399–18.417, indicating that the units are possible sources for the sulfides in the mineralisation. Both εNd(t and Isr(t of sulfide overlap with the meta-ultramafic field and Duantouya formation and dominated with mature Sr-Nd character, which indicated that the Duantouya may play an important role during the ore formation and there may exist a minor ultramafic source that is involved in the ore fluid. The S-Pb-Sr-Nd isotopic ratios are closely related to those of the Bikou Group and Duantouya Formation, which indicates that the mineralised fluid has

Banska Shtiavnica and Hodrusha gold, silver and polymetallic deposits (Slovak Republic)

International Nuclear Information System (INIS)

Jelen, Stanislav; Haber, Milan

1997-01-01

The Banska Stiavnica-Hodrusa ore district is located in the Central Slovakia, in the central upweled part of a polygenic stratovolcano. More than 120 veins are know in this ore district. They mainly occur in propylitized pyroxene andesites, diorites, quartz-diorite porphyries and granodiorites. The ores of Banska Stiavnica and Hodrusa deposits belong to the gold-silver-polymetallic hydrothermal mineralization with lead and zink prevailing over copper. Higher temperature (mezothermal?) and epithermal para genetic assemblages indicate successive mineralizing events immediately in relation to the poly phase tectonic events - deformation stages D 1 to D 4 . Later mineralizing events show evidences for heterogeneous fluids developed in a uplifted collapsing system combined with younger extension tectonics which created conditions for later influx of meteoric waters. The ore-forming processes were accompanied by concomitant decrease in temperature, salinity, oxygen and sulphur activities. Generally, the hydrothermal precious- and base metal mineralization originated in the three successive ore-cycles. Contrasting behaviour of base and precious metal complexes in the ore-forming solutions as well as diverse thermodynamic parameters cause partial temporal and spatial separation of the base- and precious metal ore mineralization. Essential portion of the carbonate-quartz vein filling with the earlier higher temperature (mezothermal?) precious metal mineralization (first mineralization ore cycle) was formed at relatively high (395-230 o C) temperatures in acid and sub neutral solutions in depth from 2.0 to 1.5 km. Temperature decrease was accompanied by gradual pH increasing from 3.6 to 4.5. The precious- and base metal mineralization of the second ore cycle consists of three mineralization stages: (1) hematite-quartz, (2) sphalerite, and (3) rhodonite-carbonate-quartz. It was formed at temperatures >300- 200 'C, pH 4.7-6.0 in depth from 0.75 to 1.60 km. The mineralization

The Krásná Hora, Milešov, and Příčovy Sb-Au ore deposits, Bohemian Massif: mineralogy, fluid inclusions, and stable isotope constraints on the deposit formation

Science.gov (United States)

Němec, Matěj; Zachariáš, Jiří

2018-02-01

The Krásná Hora-Milešov and Příčovy districts (Czech Republic) are the unique examples of Sb-Au subtype orogenic gold deposits in the Bohemian Massif. They are represented by quartz-stibnite veins and massive stibnite lenses grading into low-grade, disseminated ores in altered host rocks. Gold postdates the stibnite and is often replaced by aurostibite. The ore zones are hosted by hydrothermally altered dikes of lamprophyres (Krásná Hora-Milešov) or are associated with local strike-slip faults (Příčovy). Formation of Sb-Au deposits probably occurred shortly after the main gold-bearing event (348-338 Ma; Au-only deposits) in the central part of the Bohemian Massif. Fluid inclusion analyses suggest that stibnite precipitated at 250 to 130 °C and gold at 200 to 130 °C from low-salinity aqueous fluids. The main quartz gangue hosting the ore precipitated from the same type of fluid at about 300 °C. Early quartz-arsenopyrite veins are not associated with the Sb-Au deposition and formed from low-salinity, aqueous-carbonic fluid at higher pressure and temperature ( 250 MPa, 400 °C). The estimated oxygen isotope composition of the ore-bearing fluid (4 ± 1‰ SMOW; based on post-ore calcite) suggests its metamorphic or mixed magmatic-metamorphic origin and excludes the involvement of meteoric water. Rapid cooling of warm hydrothermal fluids reacting with "cold" host rock was probably the most important factor in the formation of both stibnite and gold.

Petrology, composition, and age of intrusive rocks associated with the Quartz Hill molybdenite deposit, southeastern Alaska.

Science.gov (United States)

Hudson, T.; Smith, James G.; Elliott, R.L.

1979-01-01

A large porphyry molybdenum deposit (Quartz Hill deposit) was recently discovered in the heart of the Coast Range batholithic complex about 70 km E of Ketchikan, SE Alaska. Intrusive rocks associated with the mineral deposit form two composite epizonal to hypabyssal stocks and many dikes in country rocks. All observed metallization and alteration is within the Quartz Hill stock. Molybdenite forms fracture coatings and occurs in veins with quartz. Alteration is widespread and includes development of secondary quartz, pyrite, K-feldspar, biotite, white mica, chlorite, and zeolite. Field relations indicate that the stocks were emplaced after regional uplift and erosion of the Coast Range batholithic complex, and K-Ar data show that intrusion and alteration took place in late Oligocene time, about 27 to 30 Ma ago. Data from the Ketchikan quadrangle indicate that porphyry molybdenum metallization in the Coast Range batholithic complex is associated with regionally extensive but spotty, middle Tertiary or younger, felsic magmatism. -from Authors

Quartz crystal fabrication facility

Science.gov (United States)

Ney, R. J.

1980-05-01

The report describes the design and operation of a five chamber, interconnected vacuum system, which is capable of cleaning, plating, and sealing precision quartz crystal units in ceramic flatpack enclosures continuously in a high vacuum environment. The production rate design goal was 200 units per eight hour day. A unique nozzle beam gold deposition source was developed to operate for extended periods of time without reloading. The source puts out a narrow beam of gold typically in the order of 2 1/2 deg included cone angle. Maximum deposition rates are in the order of 400 a/min at 5.5 in. 'throw' distance used. Entrance and exit air lock chambers expedite the material throughput, so that the processing chambers are at high vacuum for extended periods of time. A stainless steel conveyor belt, in conjunction with three vacuum manipulators, transport the resonator components to the various work stations. Individual chambers are normally separated from each other by gate valves. The crystal resonators, mounted in flatpack frames but unplated, are loaded into transport trays in a lid-frame-lid sequency for insertion into the system and exit as completed crystal units. The system utilizes molybdenum coated ball bearings at essentially all friction surfaces. The gold sources and plating mask heads are equipped with elevators and gate valves, so that they can be removed from the system for maintenance without exposing the chambers to atmosphere.

Determination of thorium in native gold by radiochemical neutron activation analysis

International Nuclear Information System (INIS)

Liu, Y.; Kraehenbuehl, U.

1995-01-01

Thorium concentrations in 11 native gold samples from different sources, e.g. placer gold, vein and lode gold were determined. Thorium was determined by radiochemical separation and measurement of protactinium from irradiated native gold samples. The chemical yield of the separation procedures is 90%. Other elements were measured by gamma-ray spectroscopy. The radiochemical separation procedures described in this work make accurate determination of Th concentrations in native gold at picogram concentrations possible. (orig.)

Underground geologic evaluation of the Grossschloppen vein-uranium deposit, West Germany

International Nuclear Information System (INIS)

Moore, S.C.; Erickson, A.J.; Kolb, S.G.; Maclean, C.J.

1983-01-01

The Grossschloppen vein-uranium deposit, Bavaria, West Germany, was examined utilizing underground workings during 1980-82 by Esso Er/ZETA/ GMbH, an affiliate of Exxon Minerals Company (EMC). Geologic evaluation entailed dense drilling of a portion of the deposit from workings constructed specifically for the program. Discovered in 1977, the deposit was initially explored by surface diamond drillholes which allowed definition of a 30-60 m wide vein system discontinuously mineralized along a 1000 m strike length and to at least a 450 m depth. The underground program was conceived as a cost effective procedure to answer questions on vein correlation, grade continuity and variability. A 1200 m decline allowed access for detailed sampling of approximately 10% of the known area of mineralization. Fanned drillholes, logged by gamma probe, were spaced to provide intersections of veins at 10 to 20 m intervals. Six cross cuts also penetrate the pitchblende and uranophane mineralization which occurs in 0.1 to 2.5 m thick quartz veins. Detailed cross-sections and level plans were constructed for resource estimates of the intensively studied portion of the vein system. The program resulted in the discovery of local, high grade areas and an average grade in the evaluated area nearly double that expected from surface drilling

Fracturing and Transformation Into Veins Beneath the Crustal Scale Brittle Ductile Transition - a Record of Co-seismic Loading and Post-seismic Relaxation

Science.gov (United States)

Nüchter, J. A.; Stöckhert, B.

2005-12-01

Metamorphic rocks approaching the crustal scale brittle-ductile transition (BDT) during exhumation are expected to become increasingly affected by short term stress fluctuations related to seismic activity in the overlying seismogenic layer (schizosphere), while still residing in a long-term viscous environment (plastosphere). The structural and microstructural record of quartz veins in low grade - high pressure metamorphic rocks from southern Evia, Greece, yields insight into the processes and conditions just beneath the long-term BDT at temperatures of about 300 to 350°C, which switches between brittle failure and viscous flow as a function of imposed stress or strain rate. The following features are characteristic: (1) The veins have formed from tensile fractures, with a typical length on the order of 10-1 to 101 m; (2) The veins are discordant with respect to foliation and all pre-existing structures, with a uniform orientation over more than 500 km2; (3) The veins show a low aspect ratio of about 10 to 100 and an irregular or characteristic flame shape, which requires distributed ductile deformation of the host rock; (4) Fabrics of the sealing vein quartz indicate that - at a time - the veins were wide open cavities; (5) The sealing quartz crystals reveal a broad spectrum of microstructural features indicative of crystal plastic deformation at high stress and temperatures of about 300 to 350°C. These features indicate that opening and sealing of the fractures commenced immediately after brittle failure, controlled by ductile deformation of the host rock. Vein-parallel shortening was generally less than about 2%. Crystals formed early during sealing were plastically deformed upon progressive deformation and opening of the vein. The structural and microstructural record is interpreted as follows: Brittle failure is proposed to be a consequence of short term co-seismic loading. Subsequent opening of the fracture and sealing to become a vein is interpreted to

A review of the anatomy and clinical significance of adrenal veins.

Science.gov (United States)

Cesmebasi, Alper; Du Plessis, Maira; Iannatuono, Mark; Shah, Sameer; Tubbs, R Shane; Loukas, Marios

2014-11-01

The adrenal veins may present with a multitude of anatomical variants, which surgeons must be aware of when performing adrenalectomies. The adrenal veins originate during the formation of the prerenal inferior vena cava (IVC) and are remnants of the caudal portion of the subcardinal veins, cranial to the subcardinal sinus in the embryo. The many communications between the posterior cardinal, supracardinal, and subcardinal veins of the primordial venous system provide an explanation for the variable anatomy. Most commonly, one central vein drains each adrenal gland. The long left adrenal vein joins the inferior phrenic vein and drains into the left renal vein, while the short right adrenal vein drains immediately into the IVC. Multiple variations exist bilaterally and may pose the risk of surgical complications. Due to the potential for collaterals and accessory adrenal vessels, great caution must be taken during an adrenalectomy. Adrenal venous sampling, the gold standard in diagnosing primary hyperaldosteronism, also requires the clinician to have a thorough knowledge of the adrenal vein anatomy to avoid iatrogenic injury. The adrenal vein acts as an important conduit in portosystemic shunts, thus the nature of the anatomy and hypercoagulable states pose the risk of thrombosis. © 2014 Wiley Periodicals, Inc.

Radioactive occurrences in veins and igneous and metamorphic rocks of New Mexico with annotated bibliography

International Nuclear Information System (INIS)

McLemore, V.T.

1982-02-01

The primary objectives of this report are to list known radioactive occurrences in veins and igneous and metamorphic rocks in New Mexico, and to provide an annotated bibliography of geologic reports concerning these regions. Only plutonic, metamorphic, vein, and Precambrian quartz-pebble conglomerate uranium deposits are considered in this report; other nonsandstone uranium deposits (such as shale, limestone, phosphorite, coal, evaporative precipitates, and fossil placer deposits) will be considered at a later time. These objectives were achieved through a literature search. Some field examinations of some of the radioactive occurrences have been completed. A table of known radioactive occurrences in veins and igneous and metamorphic rocks was compiled from the literature (Appendix I)

Geological characteristics and genesis of Niangnianggong gold-silver deposit in Liaoning Province, China

International Nuclear Information System (INIS)

Hou Zhenyuan

2013-01-01

Based on the analysis of geological characteristics and genesis of Niangnianggong deposit, this paper suggested that the deposit is controlled by the EW direction faults and belongs to quartz vein type. Average value of δ 34 S of the ore is 2.19‰, and the variation ranges from 1.6‰ to 4.9‰, which shows the feature of hydrothermal sulfur. The result of lead isotope is fall into original lead zone, which shows the feature of primeval lead system. The result of H-O isotope is close to meteoric line, which means the participation of precipitations. Rb-Sr age of ore is 186.6 Ma, which is similar to the age of diorite dike. Multi-disciplinary analysis concludes that the deposit is a quartz vein type deposit with composite hydrothermal origin. (author)

Characterization and treatment of artisanal gold mine tailings

International Nuclear Information System (INIS)

Andrade Lima, L.R.P. de; Bernardez, L.A.; Barbosa, L.A.D.

2008-01-01

The solid waste generated by artisanal gold mining, with high mercury and gold contents, can be found in several areas in the South America. The present study focused on the tailings of an artisanal gold mine area located in the Brazilian northeastern. Samples of the mine tailings were taken and used to perform a physical and chemical characterization study using X-ray diffraction, scanning electron microscopy, neutron activation, X-ray fluorescence, induced coupled plasma-mass spectrometry, among others analytical methods. The results indicate that the material is composed mainly by quartz and goethite, the characteristic size of the particles (d 50 ) is about 150 μm, and the density is close of that of quartz. The main constituents are silicon, iron, and aluminum. The tailings gold content is of about 1.8 mg/kg and the mercury content is of about 10 mg/kg. A remarkable feature of this solid waste is that the gold and mercury are both concentrated in both the fine and the coarse particles, but not in particles of intermediary size. Leaching studies indicated that the tailings are stable in weak organic acids, but soluble in alkaline and aired cyanide solutions, in which 89% of gold and 100% of mercury are extracted in 24 h. Electroleaching experiments, performed using sodium chloride as electrolyte, indicated that mercury and gold are extracted simultaneously and the recovery of both metals can be as high as 70% in 4 h. In addition, chromium, nickel, and lead are found in relatively large amounts in the solution, which indicate an effectively action of the electroleaching method to clean up solid wastes contaminated with metals

Alteration and geochemical zoning in Bodie Bluff, Bodie mining district, eastern California

Science.gov (United States)

Herrera, P.A.; Closs, L.G.; Silberman, M.L.

1993-01-01

Banded, epithermal quartz-adularia veins have produced about 1.5 million ounces of gold and 7 million ounces of silver from the Bodie mining district, eastern California. The veins cut dacitic lava flows, pyroclastic rocks and intrusions. Sinter boulders occur in a graben structure at the top of Bodie Bluff and fragments of sinter and mineralized quartz veins occur in hydrothermal breccias nearby. Explosive venting evidently was part of the evolution of the ore-forming geothermal systems which, at one time, must had reached the paleosurface. Previous reconnaissance studies at Bodie Bluff suggested that the geometry of alteration mineral assemblages and distribution of some of the major and trace elements throughout the system correspond to those predicted by models of hot-spring, volcanic rock hosted precious metal deposits (Silberman, 1982; Silberman and Berger, 1985). The current study was undertaken to evaluate these sugestions further. About 500 samples of quartz veins and altered rocks, including sinter, collected over a vertical extent of 200 meters within Bodie Bluff were petrographically examined and chemically analyzed for trace elements by emission spectrographic and atomic absorption methods. Sixty-five samples were analyzed for major elements by X-ray fluorescence methods. The results of these analyses showed that, in general, alteration mineral assemblage and vertical geochemical zoning patterns follow those predicted for hot-spring deposits, but that geochemical zoning patterns for sinter and quartz veins (siliceous deposits), and altered wall rocks are not always similar. The predicted depth-concentration patterns for some elements, notably Au, Ag, Hg, and Tl in quartz veins, and Hg, As and Ag in wall rocks were not as expected, or were perturbed by the main ore producing zone. For both quartz veins and altered wall rocks, the main ore zone had elevated metal contents. Increased concentration of many of these elements could indicate proximity to this

An insight into the adsorption and electrochemical processes occurring during the analysis of copper and lead in wines, using an electrochemical quartz crystal nanobalance.

Science.gov (United States)

Yamasaki, Alzira; Oliveira, João A B P; Duarte, Armando C; Gomes, M Teresa S R

2012-08-30

Copper and lead in wine were quantified by anodic stripping voltammetry (ASV), performed onto the gold electrode of a piezoelectric quartz crystal. Both current or mass changes could be used as analytical signals, without a statistical difference in the results (α=0.05). However, the plot of mass vs. potential provided an in depth understanding of the electrochemical processes and allowed studying adsorption phenomena. Copper interaction with fructose is an example of a process which was not possible to ignore by observing the mass change on the gold electrode of the piezoelectric quartz crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Plasma-assisted quartz-to-quartz direct bonding for the fabrication of a multilayered quartz template for nanoimprint lithography

International Nuclear Information System (INIS)

Lee, Jihye; Ali, Altun; Kim, Ki-don; Choi, Dae-guen; Choi, Jun-Hyuk; Jeong, Jun-ho; Kim, Jae-Hyun

2010-01-01

In this paper, a low-temperature plasma-assisted process is developed to realize a uniform, ultraviolet (UV) transparent and chemically inert quartz-to-quartz direct bonding. Two sets of pretests are performed in order to understand how the bond surface energy changes with the plasma exposure time and the wet etching of quartz, respectively. The developed technique is used to fabricate a multilayered quartz template for UV nanoimprint lithography (UV-NIL). The multilayered quartz template is fabricated by bonding a square piece of a standard quartz wafer, which is about 625 µm in thickness, to a wet-etched 6.35 mm thick quartz photomask plate. A fabricated multilayered template is loaded to the commercial UV-NIL tool Imprio(TM) 100, and NIL was performed successfully. The developed direct bonding technique makes it possible for standard quartz wafers, which are compatible with high-resolution semiconductor fabrication processes, to be utilized as the templates in commercial UV-NIL machines with enhanced mechanical stability.

Metalliferous deposits of the greater Helena mining region, Montana

Science.gov (United States)

Pardee, Joseph Thomas; Schrader, F.C.

1933-01-01

out to the neighboring wide intermontane valleys. The area is underlain mostly by shale, sandstone, and limestone of the upper part of the Belt series. Beds of Paleozoic and Mesozoic age occur south of the Belt area and extend from Helena west and northwest. The igneous rocks of the area include diorite and gabbro sills and dikes of probable Cretaceous age, extrusive andesite that is probably Oligocene or Miocene, and stocks of quartz monzonite, granodiorite, and quartz diorite, probably of Oligocene or Miocene age. The ore deposits of the northern districts are chiefly lodes that are valuable for gold and silver but contain some lead and copper. In the Ophir district bodies of gold and silver ore occur mainly in limestone near a body of quartz monzonite. In the Scratchgravel Hills and Grass Valley districts veins of gold quartz and veins containing lead-silver ore occur in quartz monzonite and in the adjoining metamorphic rocks. In the Austin district lodes containing gold; silver, lead, and copper are found in limestone near intrusive quartz monzonite. An unusual mineral in one of these lodes is corkite, a hydrous sulphate of lead containing arsenic. A small stock of quartz diorite in the Marysville district has invaded and domed Belt rocks. Marginal and radial fractures formed during the cooling and contraction of the igneous body became the receptacles of gold and silver veins, one of which, the Drumlummon, has produced $16,000,000. The veins filled open fractures and are characterized by a gangue of platy calcite and quartz. Lodes in Towsley Gulch in the western part of the district contain lead in addition to gold. In the Gould district a small stock of the granodiorite has invaded the Belt rocks and caused the deposition of veins similar to those near Marysville. In the Heddleston district lodes valuable for gold, silver, lead, and copper occur in Belt sedimentary rocks and diorite, some of them associated with porphyry dikes. In the Wolf Creek district veins

Efficacy of Argentum-Quartz Solution in the Treatment of Perianal Fistulas: A Preliminary Study

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Tomasello Giovanni

2015-12-01

Full Text Available Abstract Background: Nowadays, an optimal and effective medical surgery remains the gold standard for perianal fistulas. Hereby we reported preliminary results in favor of using Argentum-quartz solution for both primary and recurrent perianal fistulas. Methods: Three patients with intersphincteric and extrasphincteric fistulas were enrolled. Argentum-quartz solution was administrated twice a week for a period of 4 weeks, followed by a pause of 8 days and then another 4 weeks of treatment, totally 16 administrations. After treatment, all patients were monitored for a 4-month follow-up. Results: Complete closures of 2 extrasphincteric fistulas and a partial closure with absence of inflammation and superative phenomena in the intrasphincteric fistula were both manifested. Conclusion: Selective treatment of perianal fistulas with an argentum-quartz solution is safe and effective, and may represent a reliable alternative.

BENTON RANGE ROADLESS AREA, CALIFORNIA.

Science.gov (United States)

McKee, Edwin H.; Rains, Richard L.

1984-01-01

On the basis of a mineral survey, two parts of the Benton Range Roadless Area, California are considered to have mineral-resource potential. The central and southern part of the roadless area, near several nonoperating mines, has a probable potential for tungsten and gold-silver mineralization in tactite zones. The central part of the area has a substantiated resource potential for gold and silver in quartz veins. Detailed mapping and geochemical sampling for tungsten, gold, and silver in the central and southern part of the roadless area might indicate targets for shallow drilling exploration.

Metallogenic epoch of the Jiapigou gold belt, Jilin Province, China ...

Indian Academy of Sciences (India)

29, Xueyuan Road, Beijing 100083, People's Republic of China. 2Beijing Research .... terrane, which is separated from the central Asian orogenic belt .... Stage I formed the main body of quartz veins ...... size (20–25 μm) fluid inclusions can be observed, although most ..... Canada and Western Australia (Goldfarb et al. 2001 ...

Alteration and mineralization in the eastern part of the Soldier Mountains, Camas County, Idaho

Science.gov (United States)

Lewis, Reed S.

2001-01-01

The eastern part of the Soldier Mountains in Camas County, south-central Idaho, is underlain principally by plutonic rocks of Cretaceous and Eocene age that locally have undergone propylitic, potassic, and muscovite-quartz alteration. Muscovite- quartz alteration is Cretaceous in age and is localized along joints and fractures, some of which are filled with quartz. Associated veins have yielded minor amounts of gold. Potassic alteration is probably both Cretaceous and Eocene in age but is weakly developed and limited in extent. Propylitic alteration is Eocene in age and is pronounced around biotite granite plutons. Despite a clear association between plutons of biotite granite and widespread propylitic alteration, mineralization associated with these rocks was minimal. Mineralized areas within more mafic Eocene plutons are characterized by veins and (or) stockworks(?) enriched in copper, molybdenum, and silver, but these areas are restricted in size and have not been productive.

Ore Characteristics and Fluid Inclusion of the Base Metal Vein Deposit in Moncong Bincanai Area, Gowa, South Sulawesi, Indonesia

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Asmariyadi Asmariyadi

2014-07-01

Full Text Available DOI: 10.17014/ijog.v7i4.146This paper is dealing with ore characteristics and fluid inclusion of the Moncong Bincanai, Biringbulu Subregency of Gowa Regency, South Sulawesi Province, Indonesia. The mineralization is a vein type, with the orientation of N170oE /65oSW, hosted in open-space filling within basalt. The mineralization consists of galena, sphalerite, chalcopyrite, and pyrite. Vein thickness ranges from 5 - 17 cm, showing a crustiform banding texture, with a sequence from outer to centre: quartz, carbonate (siderite, sulphide. The quartz displays primary growth textures such as comb, crystalline, saccharoidal, and colloform. Analytical methods applied include AAS and fluid inclusion microthermometry. Chemical composition of the vein indicates an average of Pb = 47.92%, Cu = 1.27%, Zn = 1.02%, and Fe = 9.46%, which shows a significant concentration of Pb. Fluid inclusion microthermometry results indicate a range of formation temperature of 240 - 250C and salinity of the responsible hydrothermal fluid of 2.1 - 2.5 wt.% NaCl eq. The deposit is categorized into low-sulfidation epithermal deposits, which was formed within a range of 410 - 440 m below paleosurface.

Geologic map of the Dusar area, Herat Province, Afghanistan; Modified from the 1973 original map compilations of V.I. Tarasenko and others

Science.gov (United States)

Tucker, Robert D.; Stettner, Will R.; Masonic, Linda M.; Bogdanow, Anya K.

2017-10-24

The geologic maps and cross sections presented in this report are redrafted and modified versions of the Geologic map and map of useful minerals of the Dusar area (scale 1:50,000) and Geologic sketch map of the Dusar and Namak-sory ore occurrences (scale 1:10,000), located in the Herat Province, Afghanistan. The original maps and cross sections are contained in unpublished Soviet report no. 0290 (Tarasenko and others, 1973) prepared in cooperation with the Ministry of Mines and Industries of the Royal Government of Afghanistan, in Kabul during 1973 under contract no. 50728. The redrafted maps and cross sections (modified from Tarasenko and others, 1973) illustrate the geological structure and mineral occurrences of the Dusar copper-gold-silver-lead-zinc prospect area of western Afghanistan, located within the Dusar-Shaida copper and tin area of interest (AOI), Herat Province, Afghanistan.Mineralization in the Dusar area is hosted within Early Jurassic to Early Cretaceous stratified volcanic and sedimentary rocks associated with numerous diabase and gabbro-diabase intrusive bodies and is generally near a major northeast-trending system of faults and quartz veins. Host rocks consist of quartz keratophyre and quartz-feldspar porphyry, with layers of schist, phyllite, and quartz-chlorite and chlorite-sericite slate; and limestone and shale, with schist and carbonate-chlorite and chlorite slate. Known mineralization includes an extensive quartz vein system, shown on the map as the “northern occurrence,” as well as the Dusar and Namak-sory gossan zones, interpreted to have formed from remnant pyrite mineralization. The veins of the northern occurrence and their altered host rocks are known to contain anomalous to economic concentrations of precious and base metals, with concentrations locally in excess of 2 parts per million gold, 100 parts per million silver, 5 percent copper, and 1 percent lead. These veins occur in swarms, and are hosted along structures that are

Mineral resource potential map of the Benton Range Roadless Area, Mono County, California

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Donahoe, James L.; McKee, Edwin D.; Rains, Richard L.; Barnes, Donald J.; Campbell, Harry W.; Denton, David K.; Iverson, Stephen R.; Jeske, Rodney E.; Stebbins, Scott A.

1983-01-01

Tungsten-bearing rocks in the Benton Range Roadless Area occur in tactite lenses within the Paleozoic metasedimentary units that surround and are intruded by Triassic granodiorite of the Benton Range. High anomalous tungsten values were found in the southern part of the study area. Quartz-vein deposits with copper, lead, zinc, and silver may occur within the Jurassic granitic rock in the northwestern part of the area. Stream-sediment and panned-concentrate samples from the northwestern part of the roadless area, reveal anomalous values in a number of elements. Some of these elements are indicative of mineral suites that form by hydrothermal alteration and are potential metallic-ore producers. Metals having anomalous values are antimony, copper, lead, molybdenum, tin, and zinc; their presence suggests the potential for deposits of the lead-zinc-silver or copper-molybdenum type. Molybdenum and lead were identified by geochemical sampling as having low to moderate potential in the roadless area. An estimated 190,000 tons (172,000 t) of subeconomic gold and silver resources are inside the roadless area at the Gold Crown, Gold Webb, and Gold Wedge mines; another 60,000 tons (54,000 t) of subeconomic gold and silver resources are just outside the area at the Tower, Gold Webb, and Gold Wedge mines (table 1). Most of the lode gold and silver deposits are in quartz veins and shear zones. Minor amounts of copper, lead, and zinc occur in some gold deposits. About 2,240 oz (70 kg) of gold, 8,450 oz (260 kg) of silver, and 4,600 lb of lead (2,090 kg) have been produced from the roadless area. In addition, 7,257 oz (226 kg) of gold and 350 oz (11 kg) silver were produced at the Tower mine, near the area.

A structural analysis of the Minas da Panasqueira vein network and related fracture generations

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Jacques, Dominique; Vieira, Romeu; Muchez, Philippe; Sintubin, Manuel

2014-05-01

The Minas da Panasqueira is a world-class W-Cu-Sn vein-type deposit, situated within the Central Iberian Zone of the Palaeozoic Iberian Massif (Portugal). The deposit consists of a network of subhorizontal, sill-like massive quartz veins situated above the southwestern extremity of a greisen cupola, within regionally metamorphosed, isoclinally folded, lower-greenschist slates and greywackes. The greisen cupola is part of a larger intrusive complex, emplaced during the late- to post-tectonic stage of the Variscan orogeny. The late-Variscan granitoid(s) underlying the Panasqueira deposit is considered to have served as a major metal source. The structure of the network of subhorizontal extension veins, consists of numerous planar vein lobes that are separated by host-rock bridges and merge at branch-points. A structural analysis demonstrates that not only within the Panasqueira mine, but also on a more regional scale, one or more generations of flat-lying fractures are present. The veins clearly exploited these pre-existing discontinuities, as confirmed by (1) the vein geometry being directly influenced by variations in the orientation of the initial fracture sets and (2) the geometry of the rock bridges and overlapping vein morphologies, consistently showing straight-line propagating crack tips. If veining is governed by a preferential, strongly developed anisotropy in the host rock, the hypothesis of vein lobes and rock bridges forming during propagation of the parent crack by tip-line bifurcation and confinement processes (Foxford et al., 2000) does not seem plausible. Instead, we propose that the rock bridges formed from several, initially separate and small veinlets that eventually overlapped in an en echelon arrangement during progressive propagation and inflation. Bending of the rock bridges and incipient vein rotation indicate that veining occurred near the brittle-ductile transition. Using a quantitative analysis of bridge orientations, vein aspect ratios

Metallogenesis of the lode gold deposit in Ilesha area of southwestern Nigeria: inferences from lead isotope systematics

International Nuclear Information System (INIS)

Oyinloye, A.O.

2006-01-01

Studies were carried out on the geochemistry of 18 representative samples of the granite gneiss host rock, common Pb dates on six granite gneiss whole rock samples, six feldspar sample separates, and six samples from the lode gold deposit in the Ilesha schist belt. The AFM plot for the biotite granite gneiss indicated that its potlatch was derived from a subduction related tectonic setting. The granite gneiss had low U/Pb and Th/Pb ratios (0.10 to 0.31 and 0.33 to 1.31, respectively), and upper crystal Pb content of 30-47 ppm. The /sup 207/Pb/sup 204/Pb, /sup 206/Pb /sup 204/Pb, /sup 208/Pb/sup 204/Pb, were extremely homogeneous in the host rock, the feldspar, and the pyrite indicating derivation from a subduction related environment like a back arc or island arc. The two-stage Stacy and Kramers (1975) Pb-Pb model dating method of interpretation adopted in this study indicated that the granite gneiss was emplaced at 2750 +- 25 Ma in an orogen. On analysis, common Pb in pyrite yielded an average model age of 550 Ma. This Pb systematic indicated that Au was derived from the volcanics in the lIesha schist belt by hydrothermal leaching, transported through the same medium and deposited in the massive quartz veins as thio-complexes from which native gold was liberated through interaction of the ore fluid and spinals in the host rock. Studies were carried out on the geochemistry of 18 representative samples of the granite gneiss host rock, common Pb dates on six granite gneiss whole rock samples, six feldspar sample separates, and six samples from the lode gold deposit in the Ilesha schist belt. The AFM plot for the biotite granite gneiss indicated that its potlatch was derived from a subduction related tectonic setting. The granite gneiss had low U/Pb and Th/Pb ratios (0.10 to 0.31 and 0.33 to 1.31, respectively), and upper crustal Pb content of 30-47 ppm. The /sup 207/Pb /sup 204/Pb, /sup 206/Pb /sup 204/Pb, /sup 208/Pb /sup 204/Pb, were extremely homogeneous in the

Characteristics of hydrothermal alteration mineralogy and geochemistry of igneous rocks from the epithermal Co-O mine and district, Eastern Mindanao (Philippines)

Science.gov (United States)

Sonntag, Iris; Hagemann, Steffen

2010-05-01

Detailed petrographic as well as hyperspectral analyses using PIMA (Portable Infrared Mineral Analyser) and geochemical (major, trace and rare earth elements) studies were conducted on samples of the epithermal, low sulfidation Co-O mine (47,869 ounces gold produced in 2009 with an average grade of 13.3 g/t gold) and district in Eastern Mindanao (Philippines). The aims of the study were to unravel the petrogenetic origin of the various volcanic (host rocks) and intrusive rocks (potential fluid driver) as well as their relationship and influence on the hydrothermal alteration zoning and fluid chemistry. The auriferous veins at the Co-O mine were formed during two hydrothermal stages associated with the district wide D1 and D2 deformation events. Gold in stage 1 quartz veins is in equilibrium with galena and sphalerite, whereas in stage 2 it is associated with pyrite. Auriferous quartz veins of stage 1 reflect temperatures below 250° C or strong variations in pH and fO2 at higher temperatures, due to potential involvement of acidic gas or meteoric water. Cathodoluminescense studies revealed strong zonation of quartz associated with Au, presumably related to changes in the Al content, which is influenced by the pH. Plumose textures indicate times of rapid deposition, whereas saccharoidal quartz grains are related to potential calcite replacement. The geology of the Co-O mine and district is dominated by Miocene volcanic rocks (basic to intermediate flows and pyroclastics units), which are partly covered by Pliocene volcanic rocks and late Oligocene to Miocene limestones. The Miocene units are intruded by diorite (presumably Miocene in age). The epithermal mineralization event may be related to diorite intrusions. The geochemistry of all igneous rocks in the district is defined by a sub-alkaline affinity and is low to medium K in composition. Most units are related to a Miocene subduction zone with westward subduction, whereas the younger Pliocene rocks are related to

Pitchblende deposits at the Wood and Calhoun mines, Central City mining district, Gilpin County, Colorado

Science.gov (United States)

Moore, Frank R.; Butler, C.R.

1952-01-01

Pitchblende has been mined in commercial quantities from four gold- and silver-bearing pyrite-sphalerite-galena veins that occur in an area about one-half mile square on the south side of Quartz Hill, Central City district, Gilpin County, Colo. These veins are the Kirk, the German-Belcher, the Wood, and the Calhoun. Two of these veins, the Wood and the Calhoun, were studied in an attempt to determine the geologic factors favorable for pitchblende deposition. All accessible workings at the Wood and East Calhoun mines were mapped by tape and compass, and the distribution of radioactivity was studied in the field. Channel and chip samples were taken for chemical assay to compare radioactivity with uranium content. The pitchblende-bearing veins cat both pre-Cambrian granite gneiss and quartz-biotite schist; however, the gneiss was the more favorable host rock. Two bostonite porphyry dikes of Tertiary(?) age were crosscut by the Wood and Calhoun veins. The pitchblende occurs in lenses erratically distributed along the veins and in stringers extending outward from the veins. In the lenses it forms hard'. masses, but elsewhere it is Soft and powdery. The pitchblende is contemporaneous with the pyrite bat earlier than the sphalerite and galena in the same vein. All the observed pitchblende was at depths of less than 400 ft. The veins probably cannot be mined profitably for the pitchblende alone under present conditions.

Using the concentration-volume (C-V) fractal model in the delineation of gold mineralized zones within the Tepeoba porphyry Cu-Mo-Au, Balikesir, NW Turkey

Science.gov (United States)

Kumral, Mustafa; Abdelnasser, Amr; Karaman, Muhittin; Budakoglu, Murat

2016-04-01

The Tepeoba porphyry Cu-Mo-Au mineralization that located at the Biga peninsula (W Turkey) developed around the Eybek pluton concentrated at its southern contact. This mineralization that hosted in the hornfels rocks of Karakaya Complex is associated with three main alteration zones; potassic, phyllic and propylitic alterations along the fault controlled margins of the Eybek pluton and quartz stockwork veining as well as brecciation zones. As well as two mineralized zones were occurred in the mine area; hypogene and oxidation/supergene zone. The hypogene zone has differentiated alteration types; high potassic and low phyllic alteration, while the oxidation/supergene zone has high phyllic and propylitic alterations. This work deals with the delineation of gold mineralized zone within this porphyry deposit using the concentration-volume (C-V) fractal model. Five zones of gold were calculated using its power-law C-V relationship that revealed that the main phase of gold mineralization stated at 5.3083 ppm Au concentration. In addition, the C-V log-log plot shows that the highly and moderately Au mineralization zone developed in western part of deposit correlated with oxidation zone related to propylitic alteration. On the other hand, its weakly mineralization zone has a widespread in the hypogene zone related to potassic alteration. This refers to the enrichment of gold and depletion of copper at the oxidation/supergene zone is due to the oxidation/supergene alteration processes that enrich the deposits by the meteoric water. Keywords: Concentration-volume (C-V) fractal model; gold mineralized zone; Tepeoba porphyry Cu-Mo-Au; Balikesir; NW Turkey.

Role of Substrate on Quartz Cementation in Quartz Aggregates

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Farver, J. R.; Winslow, D.; Onasch, C.

2010-12-01

Quartz cementation in quartz aggregates has been experimentally investigated. The starting material was disaggregated detrital quartz grains from the well-sorted, mature St. Peter Sandstone. The ‘as-is’ grains have patches of iron oxide coatings and some have euhedral overgrowths that contain iron oxide dust rims. In addition a set of experiments was run using grains that were cleaned by soaking in sodium hydrosulfite and sodium bisulfate solutions to remove exposed iron oxide coatings. Experimental charges consisted of amorphous silica powder (≈30 mg) to provide a source of silica for the quartz cement, AlCl3 powder (≈3 mg) to provide a tracer for Cathodoluminescence (CL) identification of cement formed during the experiment, 25 wt% NaCl brine solution (≈25 mg) to increase the silica solubility and to better mimic oil field brines, and the natural quartz grains (100-130 mg). The charges were weld-sealed in Au capsules and run in cold-seal pressure vessels at 250°C to 450°C at 150 MPa confining pressure for up to 8 weeks. After the experiments, the samples were vacuum impregnated with a low viscosity epoxy containing a blue dye. After curing, the sample charge was sawn in half along its long axis and one half was polished (to 1 micron diamond paste) for analysis. The nature and amount of quartz cement in the samples were determined by a combination of CL, light microscopy, and scanning electron microscopy. Photomosaics of the samples were created and the amount of cement, porosity, and average grain sizes were determined by point-counting. The cement formed during the experiment was easily recognized from the quartz grains (and previous overgrowths) by the difference in luminescence. The results indicate the amorphous silica powder provides a ready source for silica for quartz cementation due to its greater solubility than the quartz. The cementation rates are rapid (>14% cement formed in 2 weeks at 450°C and >7% in 8 weeks at 250°C). Compared to

Uranium deposits in Proterozoic quartz-pebble conglomerates

International Nuclear Information System (INIS)

1987-09-01

This report is the result of an effort to gather together the most important information on uranium deposits in Proterozoic quartz-pebble conglomerates in the United States of America, Canada, Finland, Ghana, South Africa and Australia. The paper discusses the uranium potential (and in some cases also the gold potential in South Africa, Western Australia and Ghana) in terms of ores, sedimentation, mineralization, metamorphism, placers, geologic formations, stratigraphy, petrology, exploration, tectonics and distribution. Geologic history and application of geologic models are also discussed. Glacial outwash and water influx is also mentioned. The uranium deposits in a number of States in the USA are covered. The Witwatersrand placers are discussed in several papers. Refs, figs, tabs

Remote sensing detection of gold related alteration zones in Um Rus area, Central Eastern Desert of Egypt

Science.gov (United States)

Amer, Reda; Kusky, Timothy; El Mezayen, Ahmed

2012-01-01

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Phased Array L-band Synthetic Aperture Radar (PALSAR) images covering the Um Rus area in the Central Eastern Desert of Egypt were evaluated for mapping geologic structure, lithology, and gold-related alteration zones. The study area is covered by Pan-African basement rocks including gabbro and granodiorite intruded into a variable mixture of metavolcanics and metasediments. The first three principal component analyses (PCA1, PCA2, PCA3) in a Red-Green-Blue (RGB) of the visible through shortwave-infrared (VNIR + SWIR) ASTER bands enabled the discrimination between lithological units. The results show that ASTER band ratios ((2 + 4)/3, (5 + 7)/6, (7 + 9)/8) in RGB identifies the lithological units and discriminates the granodiorite very well from the adjacent rock units.The granodiorites are dissected by gold-bearing quartz veins surrounded by alteration zones. The microscopic examination of samples collected from the alteration zones shows sericitic and argillic alteration zones. The Spectral Angle Mapper (SAM) and Spectral Information Divergence (SID) supervised classification methods were applied using the reference spectra of the USGS spectral library. The results show that these classification methods are capable of mapping the alteration zones as indicated by field verification work. The PALSAR image was enhanced for fracture mapping using the second moment co-occurrence filter. Overlying extracted faults and alteration zone classification images show that the N30E and N-S fractures represent potential zones for gold exploration. It is concluded that the proposed methods can be used as a powerful tool for ore deposit exploration.

Combined atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and quartz crystal microbalance (QCM) studies of glucose oxidase (GOx) immobilised onto self-assembled monolayer on the gold film

International Nuclear Information System (INIS)

Losic, D.; Shapter, J.; Gooding, J.; Erokin, P.; Short, K.

1999-01-01

In fabrication of biosensors, self-assembled monolayers (SAM) are an attractive method of immobilising enzymes at electrode surface since it allows precise control over the amount and spatial distribution of the immobilized enzyme. The covalent attachment of glucose oxidase (GOx) to a carboxylic terminated SAM chemisorbed onto gold films was achieved via carbodiimide activation of the carboxylic acids to a reactive intermediate susceptible to nucleophilic attack by amines on free lysine chains of the enzyme. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and quartz crystal microbalance (QCM) measurements were used for characterisation of GOx modified gold surfaces. Tapping mode AFM studies have revealed that GOx molecules form slightly disordered arrays of pentagonal or hexagonal clusters. Observed features of immobilised GOx are distributed as a submonolayer on the SAM surface which has allowed visualisation of native and unfolded enzyme structure. The presence of the SAM and enzyme on the gold surface was detected by XPS spectroscopy. Spectra show typical peaks for the C 1s, O 1s and N 1s regions. A kinetic study of the adsorption of GOx onto activated SAM using in-situ QCM allowed determination the amount of immobilised GOx on the layer and consequently the optimal immobilisation conditions. Performance parameters of the biosensor such as sensitivity to glucose concentration as a function of enzyme loading were evaluated amperometrically using the redox mediator p-benzoquinone

Geology of the Vienna Mineralized Area, Blaine and Camas Counties, Idaho

Science.gov (United States)

Mahoney, J. Brian; Horn, Michael C.

2005-01-01

The Vienna mineralized area of south-central Idaho was an important silver-lead-producing district in the late 1800s and has intermittently produced lead, silver, zinc, copper, and gold since that time. The district is underlain by biotite granodiorite of the Cretaceous Idaho batholith, and all mineral deposits are hosted by the biotite granodiorite. The granodiorite intrudes Paleozoic sedimentary rocks of the Sun Valley Group, is overlain by rocks of the Eocene Challis Volcanic Group, and is cut by numerous northeast-trending Eocene faults and dikes. Two mineralogically and texturally distinct vein types are present in a northwest- and east-trending conjugate shear-zone system. The shear zones postdate granodiorite emplacement and joint formation, but predate Eocene fault and dike formation. Ribbon veins consist of alternating bands of massive vein quartz and silver-sulfide (proustite and pyrargyrite) mineral stringers. The ribbon veins were sheared and brecciated during multiple phases of injection of mineralizing fluids. A quartz-sericite-pyrite-galena vein system was subsequently emplaced in the brecciated shear zones. Both vein systems are believed to be the product of mesothermal, multiphase mineralization. K-Ar dating of shear-zone sericite indicates that sericitization occurred at 80.7?2.8 Ma; thus mineralization in the Vienna mineralized area probably is Late Cretaceous in age.

Geometric Analysis of Vein Fracture Networks From the Awibengkok Core, Indonesia

Science.gov (United States)

Khatwa, A.; Bruhn, R. L.; Brown, S. R.

2003-12-01

Fracture network systems within rocks are important features for the transportation and remediation of hazardous waste, oil and gas production, geothermal energy extraction and the formation of vein fillings and ore deposits. A variety of methods, including computational and laboratory modeling have been employed to further understand the dynamic nature of fractures and fracture systems (e.g. Ebel and Brown, this session). To substantiate these studies, it is also necessary to analyze the characteristics and morphology of naturally occurring vein systems. The Awibengkok core from a geothermal system in West Java, Indonesia provided an excellent opportunity to study geometric and petrologic characteristics of vein systems in volcanic rock. Vein minerals included chlorite, calcite, quartz, zeolites and sulphides. To obtain geometric data on the veins, we employed a neural net image processing technique to analyze high-resolution digital photography of the veins. We trained a neural net processor to map the extent of the vein using RGB pixel training classes. The resulting classification image was then converted to a binary image file and processed through a MatLab program that we designed to calculate vein geometric statistics, including aperture and roughness. We also performed detailed petrographic and microscopic geometric analysis on the veins to determine the history of mineralization and fracturing. We found that multi-phase mineralization due to chemical dissolution and re-precipitation as well as mechanical fracturing was a common feature in many of the veins and that it had a significant role for interpreting vein tortuosity and history of permeability. We used our micro- and macro-scale observations to construct four hypothetical permeability models that compliment the numerical and laboratory modeled data reported by Ebel and Brown. In each model, permeability changes, and in most cases fluctuates, differently over time as the tortuosity and aperture of

The Tintina Gold Belt - A global perspective

Science.gov (United States)

Goldfarb, Richard J.; Hart, Craig J.R.; Miller, Marti L.; Miller, Lance D.; Farmer, G. Lang; Groves, David I.; Tucker, Terry L.; Smith, Moira T.

2000-01-01

The so-called Tintina Gold Belt extends for more than 1000 km along the length of the northern North American Cordillera. Middle to Late Cretaceous Au deposits within the belt have various similar characteristics, among which are a spatial and temporal association with magmatism; Bi-W-Te signatures in deposits hosted by granitod stocks and As-Sb signatures where hosted by sedimentary rocks and dyke systems; and δ180 values consistently > 12 per mil for Au-bearing quartz. Nevertheless significant differences in structural styles, levels of deposit emplacement, ore-fluid chemistry, and Au grades suggest that the characteristics represent a broad range of deposit types. Many of these are best classified as orogenic Au deposits in the Yukon-Tanana terrane, as epithermal and porphyry-style Au deposits in the Kuskokwim region, and as Au-bearing, granite-related veins and stockworks, replacements, and skarns, as well as associated polymetallic lodes, in central Yukon. The diverse types of Au deposits and associated plutons of the Tintina Gold Belt collectively define a 45-m.y.-long period of arc magmatism that migrated northwesterly, for about 1000 km, across the active collisional margin of Cretaceous northwestern North America. The initiation of fluid flow and plutonism in Albian time seems to correlate with the onset of oblique subduction and dextral strike-slip on the Denali-Farewell, Tintina-Kaltag, and related fault systems. Initial Au-vein formation and subduction-related magmatism at about 115-110 Ma (e.g., including the Goodpaster and Fortymile districts), within the seaward side of the Yukon-Tanana terrane, correlate with the arrival of the Wrangellia superterrane off the continental margin. Dextral translation of the allochthonous Wrangellia block was associated with the migration of the thermal pulse to the northwest at about 95-90 Ma. Orogenic (or so­ called mesotherrnal) and granitoid-related Au deposits formed across the width of the Yukon

Geochemical Characteristics of Metamorphic Rock-Hosted Gold Deposit At Onzon-Kanbani Area, Central Myanmar

Directory of Open Access Journals (Sweden)

Aung Tay Zar

2017-09-01

Full Text Available Gold and associated base metal mineralization of Onzon-Kabani area located in the western border of generally N-S trending Mogoke Metamorphic Belt where well-known Sagaing fault is served as a western boundary of this area. In this research area, many artisanal and small-scale gold mines were noted in last three decades. Gold mineralization is hosted in marble and gneiss unit of research area but most common in marble unit. Variety of igneous intrusions are also observed in research area. Mineralizations are observed as fissure filling veins as well as lesser amount of disseminated nature in marble unit. Mineralogically, gold are associated with other base metal such as pyrite, galena, sphalerite, chalcopyrite, marcasite and arsenopyrite. Hydrothermal alteration halos are developed in peripheral of hydrothermal conduits or mineralization veins from proximal to distal such as 1 silicic, 2 sericite-illite, and 3 propylitic alteration.  Most of hydrothermal minerals from each altered zones showed that near neutral condition of pH (e.g. adularia, calcite, illite, sericite and chlorite. Alternatively, hydrothermal alteration zones that show with ore minerals such as native gold, electrum, sphalerite, galena, chalcopyrite, arsenopyrite and marcasite which mostly observed in silicic alteration zone. Typical boiling characters of vein textures and fluid inclusion petrography are observed in hydrothermal system of research area. Boiling, cooling and mixing are possiblily responsible for gold deposition in hydrothermal system. In this paper, authors are documented to clarify the type of mineralization based on hydrothermal alterations, ore and gangue mineral assemblages and fluid inclusion study. All of these data can describe and play an important role for both with respect to understanding deposit genesis and in mineral exploration.

Granite-related Yangjiashan tungsten deposit, southern China

Science.gov (United States)

Xie, Guiqing; Mao, Jingwen; Li, Wei; Fu, Bin; Zhang, Zhiyuan

2018-04-01

The Yangjiashan scheelite-bearing deposit (38,663 metric tons of WO3 with an average ore grade of 0.70% WO3) is hosted in quartz veins in a biotite monzogranite intrusion and surrounding slate in the Xiangzhong Metallogenic Province of southern China. The monzogranite has a zircon SHRIMP U-Pb age of 406.6 ± 2.8 Ma (2σ, n = 20, MSWD = 1.4). Cassiterite coexisting with scheelite yields a weighted mean 206Pb/238U age of 409.8 ± 5.9 Ma (2σ, n = 30, MSWD = 0.20), and molybdenite intergrown with scheelite yields a weighted mean Re-Os age of 404.2 ± 3.2 Ma (2σ, n = 3, MSWD = 0.10). These results suggest that the Yangjiashan tungsten deposit is temporally related to the Devonian intrusion. The δD and calculated δ18OH2O values of quartz intergrown with scheelite range from - 87 to - 68‰, and - 1.2 to 3.4‰, respectively. Sulfides have a narrow range of δ34S values of - 2.9 to - 0.7‰ with an average value of - 1.6‰ (n = 16). The integration of geological, stable isotope, and geochronological data, combined with the quartz-muscovite greisen style of ore, supports a magmatic-hydrothermal origin for the tungsten mineralization. Compared to the more common tungsten skarn, quartz-wolframite vein, and porphyry tungsten deposits, as well as orogenic gold deposits worldwide, the Yangjiashan tungsten deposit is an unusual example of a granite-related, gold-poor, scheelite-bearing quartz vein type of deposit. The calcium needed for the formation of scheelite is derived from the sericitization of calcic plagioclase in the monzogranite and Ca-bearing psammitic country rocks, and the relatively high pH, reduced and Ca-rich mineralizing fluid may be the main reasons for the formation of scheelite rather than wolframite at Yangjiashan.

Study of green quartz of hydrothermal origin treated by gamma radiation

International Nuclear Information System (INIS)

Enokihara, Cyro Teiti

2013-01-01

heating techniques (3200 ppm), probably due to remaining silanol complexes.To trace the influence of water on color formation, samples from 3 different geological settings (high temperature pegmatitic quartz with Al and Li, from Santana de Araguaia; intermediate temperature vein quartz with Al but without water from Curvelo; amethyst with more Fe, less Al and small silanol content from Brejinho, and low temperature regimes from geodes, high silanol and high molecular water, cations similar to the above mentioned) have been analyzed by NIR spectroscopy.The former will not show green color, only the latter one. It may be mentioned that even in geodes one has crystals with high and intermediate water content coexisting. The crystals with high silanol and molecular water are the ones to treat by radiation. The radiation induced color is heat and UV sensible with bleaching by longer exposure to these factors. (author)

Gold and uranium metallogenesis in the framework of Neo-proterozoic crust growth and differentiation: example of the Mayo-Kebbi Massif (Chad) in the Central Africa Orogenic belt

International Nuclear Information System (INIS)

Mbaguedje, Diondoh

2015-01-01

The Mayo Kebbi massif located in southwestern Chad between the Congo craton in the South, the West African craton in the west and the Sahara meta-craton to the east exposes a segment of Neo-proterozoic juvenile crust accreted in the Central African orogenic belt during the Pan African orogeny. It consists of two greenstone belts (Zalbi and Goueygoudoum) separated by the May Kebbi calc-alkaline batholith complexes and intruded by calc-alkaline high-K granitic plutons. The whole is covered by Phanerozoic sedimentary formations. The greenstone belts contain sulphide zones hosted mainly by meta-plutonic rocks (granodiorites) and meta-basalts and meta-volcaniclastics. The mineralization comprises pyrite, pyrrhotite, arsenopyrite, chalcopyrite, pentlandite, pentlandite silver, pentlandite cobaltiferous, sphalerite, cobaltite. These sulphides are disseminated, aggregated in form of layers or are filling veins and cracks. The greenstones also contain quartz veins with calcite and chlorite comprising a mineralization made of pyrite, chalcopyrite, galena and gold. Gold is present both as native crystals and as electrum. The high-K calc-alkaline Zabili granitic pluton hosts uranium mineralization related to a superposition of: (1) ductile deformation and metasomatic alteration implying the interaction between magmatic minerals with a Na-rich fluid, of potential magmatic origin, coeval to the main deposition of uranium oxides, followed by (2) brittle deformation and deposition of secondary hydrated uranium silicates involving a Na-Ca-rich fluid. We propose that these uranium mineralizations represent the extreme expression of crustal differentiation as a result of Pan-African reworking of a Neo-proterozoic juvenile crustal segment. (author) [fr

Sclerotherapy of Varicose Veins and Spider Veins

Science.gov (United States)

... Index A-Z Sclerotherapy of Varicose Veins and Spider Veins Sclerotherapy uses injections from a very fine, ... Sclerotherapy? What is Sclerotherapy of Varicose Veins and Spider Veins? Sclerotherapy is a minimally invasive treatment used ...

Electrochemistry, surface plasmon resonance, and quartz crystal microbalance: an associative study on cytochrome c adsorption on pyridine tail-group monolayers on gold.

Science.gov (United States)

Paulo, Tércio de F; de Sousa, Ticyano P; de Abreu, Dieric S; Felício, Nathalie H; Bernhardt, Paul V; Lopes, Luiz G de F; Sousa, Eduardo H S; Diógenes, Izaura C N

2013-07-25

Quartz crystal microbalance (QCM), surface plasmon resonance (SPR), and electrochemistry techniques were used to study the electron-transfer (ET) reaction of cytochrome c (Cyt c) on gold surfaces modified with thionicotinamide, thioisonicotinamide, 4-mercaptopyridine, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, 5-phenyl-1,3,4-oxadiazole-2-thiol, 4,4'-bipyridine, and 4,4'-dithiopyridine. The electrochemical results showed that the ET process is complex, being chiefly diffusional with steps depending on the orientation of the pyridine or phenyl tail group of the modifiers. The correlation between the electrochemical results and those acquired by SPR and QCM indicated the presence of an adlayer of Cyt c adsorbed on the thiolate SAMs. This adlayer, although being not electroactive, is essential to assess the ET reaction of Cyt c in solution. The results presented in this work are consistent with the statement (Feng, Z. Q.; Imabayashi, S.; Kakiuchi, T.; Niki, K. J. Electroanal. Chem. 1995, 394, 149-154) that the ET reaction of Cyt c can be explained in terms of the through-bond tunneling mechanism.

Genetic Aspects of Gold Mineralization at Some Occurrences in the Eastern Desert of Egypt

Science.gov (United States)

Abd El Monsef, M.; Slobodník, M.; Salem, I. A.

2012-04-01

The Eastern Desert of Egypt is well known as a gold-mining area since ancient times, there're more than 95 gold deposits and occurrences spread the whole area covered by the basement rocks of Precambrian age. The basement rocks of the Eastern Desert of Egypt constitute the Nubian Shield that has formed a continuous part of the Arabian-Nubian Shield before the opening of Red Sea (Oligocene-Early Miocene). Commonly, the system of gold-bearing quartz veins in the Eastern Desert is clearly structural controlled related to brittle-ductile shear zones that mostly developed during late deformational stages of the evolution history for basement rocks in the Eastern Desert. This running study principally aims to contribute the mineral resource potential of the gold deposits in Egypt, so particularly Fatira, Gidami and Atalla occurrences have been involved into a comprehensive study based on field, structural, mineralogical, geochemical and genetic investigations. It is intended to better understanding for the characteristics, distribution controls, conditions and age of mineralization in relation to the age of the hosting rocks intrusion to find if there're genetic links between the gold mineralization and the evolution of the host intrusive complex. Several authors suggested that the gold mineralization was related to the intrusion of the (postorogenic) Younger granites. Other authors interpret these deposits as products of hydrothermal activity induced either by metamorphism or cooling effects of early Paleozoic magmatism or as combined metamorphic/magmatic episodes. The prime focus will be directed to the ore itself and the associated hydrothermal alteration zones based on detailed maps and well-distributed samples network and geochemical anomalies distribution. The laboratory studies included microscopic examination (reflecting and transmitting microscopy) to allow for determination of the hosting rocks types and mineralogical changes related to the gold mineralization

Study on Sumbawa gold recovery using centrifuge

Science.gov (United States)

Ferdana, A. D.; Petrus, H. T. B. M.; Bendiyasa, I. M.; Prijambada, I. D.; Hamada, F.; Sachiko, T.

2018-01-01

The Artisanal Small Gold Mining in Sumbawa has been processing gold with mercury (Hg), which poses a serious threat to the mining and global environment. One method of gold processing that does not use mercury is by gravity method. Before processing the ore first performed an analysis of Mineragraphy and analysis of compound with XRD. Mineragraphy results show that gold is associated with chalcopyrite and covelite and is a single particle (native) on size 58.8 μm, 117 μm up to 294 μm. characterization with XRD shows that the Sumbawa Gold Ore is composed of quartz, pyrite, pyroxene, and sericite compounds. Sentrifugation is one of separation equipment of gravity method to increase concentrate based on difference of specific gravity. The optimum concentration result is influenced by several variables, such as water flow rate and particle size. In this present research, the range of flow rate is 5 lpm and 10 lpm, the particle size - 100 + 200 mesh and -200 +300 mesh. Gold concentration in concentrate is measured by EDX. The result shows that the optimum condition is obtained at a separation with flow rate 5 lpm and a particle size of -100 + 200 mesh.

Examples of possible movement of gold in solution in the Witwatersrand, Ventersdorp, and Transvaal systems

International Nuclear Information System (INIS)

Whiteside, H.C.M.

1981-01-01

Many South African geologists consider that gold especially, and probably uraninite, as well as other heavy minerals such as zircon, chromite, and diamond, are detrital in the Precambrian quartz-pebble conglomerates of South Africa. It is suggested here that solution of gold and its redeposition elsewhere may have played a part in its enrichment or impoverishment. Two examples of possible solution of gold are cited, and the lack of modern placers associated with auriferous Witwatersrand is briefly discussed

Study of tibial nerve regeneration in Wistar rats in primary neurorrhaphy with and without gap, wrapped in vein segments.

Science.gov (United States)

Bastos Dos Santos, Ewerton; Fernandes, Marcela; Gomes Dos Santos, João Baptista; Mattioli Leite, Vilnei; Valente, Sandra Gomes; Faloppa, Flávio

2012-01-01

This study compared nerve regeneration in Wistar rats, using epineural neurorrhaphy with a gap of 1.0 mm and without a gap, both wrapped with jugular vein tubes. Motor neurons in the spinal cord between L3 and S1 were used for the count, marked by exposure of the tibial nerve to Fluoro-Gold (FG). The tibial nerves on both sides were cut and sutured, with a gap on one side and no gap in the other. The sutures were wrapped with a jugular vein. Four months after surgery the tibial nerves were exposed to Fluoro-Gold and the motor neuron count performed in the spinal cord. The results were statistically analyzed by the paired Wilcoxon test. There was a statistical difference between the groups with and without gap in relation to the motor neuron count (p=0.013). The epineural neurorraphy without gap wrapped with jugular vein showed better results for nerve regeneration than the same procedure with gap. Experimental Study .

Sources of metals in the Porgera gold deposit, Papua New Guinea: Evidence from alteration, isotope, and noble metal geochemistry

Science.gov (United States)

Richards, Jeremy P.; McCulloch, Malcolm T.; Chappell, Bruce W.; Kerrich, Robert

1991-02-01

The Porgera gold deposit is spatially and temporally associated with the Late Miocene, mafic, alkalic, epizonal Porgera Intrusive Complex (PIC), located in the highlands of Papua New Guinea (PNG). The highlands region marks the site of a Tertiary age continent-island-arc collision zone, located on the northeastern edge of the Australasian craton. The PIC was emplaced within continental crust near the Lagaip Fault Zone, which represents an Oligocene suture between the craton and volcano-sedimentary rocks of the Sepik terrane. Magmatism at Porgera probably occurred in response to the Late Miocene elimination of an oceanic microplate, and subsequent Early Pliocene collision between the craton margin and an arc system located on the Bismarck Sea plate. Gold mineralization occurred within 1 Ma of the time of magmatism. Metasomatism accompanying early disseminated Au mineralization in igneous host rocks resulted in additions of K, Rb, Mn, S, and CO 2, and depletions of Fe, Mg, Ca, Na, Ba, and Sr; rare-earth and high-field-strength elements remained largely immobile. Pervasive development of illite-K-feldspar-quartz-carbonate alteration assemblages suggests alteration by mildly acidic, 200 to 350°C fluids, at high water/ rock ratios. Strontium and lead isotopic compositions of minerals from early base-metal sulphide veins associated with K-metasomatism, and later quartz-roscoelite veins carrying abundant free gold and tellurides, are remarkably uniform (e.g., 87Sr /86Sr = 0.70745 ± 0.00044 [n = 10] , 207Pb /204Pb = 15.603 ± 0.004 [n = 15] ). These compositions fall between those of unaltered igneous and sedimentary host rocks, and specifically sedimentary rocks from the Jurassic Om Formation which underlies the deposit (igneous rocks: 87Sr /86Sr ≈ 0.7035 , 207Pb /204Pb ≈ 15.560 ; Om Formation: 87Sr /86Sr |t~ 0.7153 , 207Pb /204Pb ≈ 15.636 ). It is therefore suggested that the hydrothermal fluids acquired their Sr and Pb isotopic signatures by interaction with, or

Geochemical evidence for subduction in the early Archaean from quartz-carbonate-fuchsite mineralization, Isua Supracrustal Belt, West Greenland

DEFF Research Database (Denmark)

Pope, Emily Catherine; Rosing, Minik Thorleif; Bird, Dennis K.

Quartz, carbonate and fuchsite (chromian muscovite) is a common metasomatic assemblage observed in orogenic gold systems, both in Phanerozoic convergent margin settings, and within supracrustal and greenstone belts of Precambrian rocks. Geologic and geochemical observations in younger orogenic...... systems suggest that ore-forming metasomatic fluids are derived from subduction-related devolitilization reactions, implying that orogenic Au-deposits in Archaean and Proterozoic supracrustal rock suites are related to subduction-style plate tectonics beginning early in Earth history. Justification...... with Phanerozoic orogenic deposits and that this type of metasomatism is a unique result of subduction-related processes. Fuchsite from the ISB has a δ18O and δD of 7.7 to 17.9‰ and -115 to -61‰, respectively. δ18O of quartz from the same rocks is between 10.3 and 18.6‰. Muscovite-quartz oxygen isotope thermometry...

Detection of Volatile Organic Compound Gas Using Localized Surface Plasmon Resonance of Gold Nanoparticles

International Nuclear Information System (INIS)

Sri Nengsih; Akrajas Ali Umar; Muhamad Mat Salleh; Muhammad Yahaya

2011-01-01

This paper reports on the detection of several organic vapors using the unique characteristic of localized surface plasmon resonance (LSPR) gold nanoparticles. Gold nanoparticles on quartz substrate were prepared using seed mediated growth method. In a typical process, gold nanoparticles with average size ca. 36 nm were obtained to densely grown on the substrate. Detection of gas was based on the change in the LSPR of the gold nanoparticles film upon the exposure to the gas sample. It was found that gold nanoparticles were sensitive to the presence of volatile organic compound (VOC) gas from the change in the surface plasmon resonance (SPR) intensity. The mechanism for the detection of VOCs gas will be discussed. (author)

Carbon-oxygen isotopes and rare earth elements as an exploration vector for Carlin-type gold deposits: A case study of the Shuiyindong gold deposit, Guizhou Province, SW China

Science.gov (United States)

Tan, Qin-Ping; Xia, Yong; Wang, Xueqiu; Xie, Zhuo-Jun; Wei, Dong-Tian

2017-10-01

The Shuiyindong gold deposit is a deeply concealed strata-bound Carlin-type deposit in southwestern Guizhou Province, China. The deposit lies on the eastern limb of the Huijiabao anticline with ores mainly along the anticline axis and hosted in bioclastic limestone, containing calcite veins, of the Permian Longtan Formation units. In this study, we measured carbon and oxygen isotopic ratios and rare earth element (REE) concentrations of the host rocks and calcite veins along a profile across the Shuiyindong deposit. Orebodies in the upper unit of the Longtan Formation have higher δ18O values (20.6-22.4‰) and lower δ13C values (-3.7 to -0.5‰) than the country rocks (δ18O: 18.8-21.4‰; δ13C: -0.7 to 0.8‰). However, there are no obvious trends of δ18O and δ13C values from the country rocks to the orebodies in the middle unit of the Longtan Formation. The spatial distribution of the calcite veins displays distinct halos of δ13C and δ18O values and REE concentrations. Calcite veins along the anticlinal axis and major reverse fault are enriched in Middle REE (Sm, Eu, Gd, and Tb) and 18O and depleted in 13C. Surficial veining calcite-filled fractures/faults that connect to deep concealed strata-bound gold mineralization systems can be vectors toward deep ores in southwestern Guizhou Province, China.

Blue and red thermoluminescence of natural quartz in the temperature region from -196 to 400deg. C

International Nuclear Information System (INIS)

Hashimoto, Tetsuo; Yanagawa, Yuji; Yawata, Takashi

2007-01-01

Quartz samples of three different origins were γ-irradiated with 20kGy at room temperature or at the temperature of liquid nitrogen (-196 deg. C), and analyzed by on-line TL-emission spectrometry over two temperature ranges: above 200deg. C (high-temperature region) and -196 to 200deg. C (low-temperature region). The emission spectra in the high-temperature region could be separated into intense blue TL (BTL) or red TL (RTL) properties. All quartz samples displayed more or less both properties of BTL and RTL in the low temperature region, shifting the BTL-emission spectra towards violet. Particularly, volcanically originated quartz (RTL, Medeshima) showed highly complex BTL and RTL peaks in the low-temperature region, and a stronger simple RTL peak in the high temperature. These complex glow-curve peaks are considered to reflect the presence of many crystal defects and much content of impurities in the volcanically formed quartz. In the glow-curve measurements, Brazilian quartz (quartz-vein origin) gave weak RTL and intense BTL in the low-temperature range, followed by faint emission of BTL in the high-temperature side. On the other hand, the radiation-induced colored (CC) part of a Madagascan crystal rock slice (hydrothermal origin) showed intense BTL together with slight RTL in the low temperatures, followed by strong BTL and appreciable strength of RTL in the high temperatures. The BTL-emission pattern (TL-color image) of a Madagascan slice showed a complementary relationship between irradiations at liquid-nitrogen temperature and at room temperature. To explain these radiation-induced phenomena from quartz, hydrogen radicals and Li + ions, derived from radiolysis products of OH-related impurities, could operate to eliminate the BTL centers by recombination below the room temperature

Gold nanoparticles administration induced prominent inflammatory, central vein intima disruption, fatty change and Kupffer cells hyperplasia

Directory of Open Access Journals (Sweden)

Abdelhalim Mohamed

2011-08-01

Full Text Available Abstract Background Advances in nanotechnology have identified promising candidates for many biological, biomedical and biomedicine applications. They are being increasingly exploited for medical uses and other industrial applications. The aim of the present study was to investigate the effects of administration of gold nanoparticles (GNPs on inflammatory cells infiltration, central vein intima disruption, fatty change, and Kupffer cells hyperplasia in the hepatic tissue in an attempt to cover and understand the toxicity and the potential threat of their therapeutic and diagnostic use. Methods A total of 70 healthy male Wistar-Kyoto rats were exposed to GNPs received 50 or 100 μl of GNPs infusion of 10, 20 and 50 nm GNPs for 3 or 7 days. Animals were randomly divided into groups, 12 GNPs-treated rats groups and one control group (NG. Groups 1, 2 and 3 received infusion of 50 μl GNPs of size 10 nm (3 or 7 days, size 20 nm (3 or 7 days and 50 nm (3 or 7 days, respectively; while groups 4, 5 and 6 received infusion of 100 μl GNPs of size 10 nm, size 20 nm and 50 nm, respectively. Results In comparison with respective control rats, exposure to GNPs doses has produced alterations in the hepatocytes, portal triads and sinusoids. The alterations in the hepatocytes were mainly vacuolar to hydropic degeneration, cytopasmic hyaline vacuolation, polymorphism, binucleation, karyopyknosis, karyolysis, karyorrhexis and necrosis. In addition, inflammatory cell infiltration, Kupffer cells hyperplasia, central veins intima disruption, hepatic strands dilatation and occasional fatty change together with a loss of normal architechiture of hepatic strands were also seen. Conclusions The alterations induced by the administration of GNPs were size-dependent with smaller ones induced more affects and related with time exposure of GNPs. These alterations might be an indication of injured hepatocytes due to GNPs toxicity that became unable to deal with the

The usefulness and the limitation of MR angiography for the evaluation of colateral veins in portal hypertension

International Nuclear Information System (INIS)

Komazaki, Toshio

1994-01-01

The usefulness and the limitation of magnetic resonance angiography (MRA) for the assessment of the portal vein and its branches, i.e., the collateral veins of portal hypertensive patients, were studied. In a total of 22 patients with portal hypertension, both MRA and percutaneous transhepatic portography (PTP) were done at the same time. MRA and PTP images were read at random by three observers. The discriminative scores, decided from the grades of clearness of images, were calculated for six portal venous vessels. The discrimination of the portal vein, splenic vein, paraumbilical vein and gastrorenal shunt was easy on condition that they were clearly visualized by PTP. Thus the accuracy of MRA, which was calculated by comparing it with PTP, the gold standard, was high and above 95%. Regarding the left gastric vein and short gastric vein, the accuracy of MRA were lower than the former four vessels but were still above 80%. MRA, the noninvasive method, seems useful for the first choice to see the total image of portal venous system. (author)

Genesis of the Assif El Mal Zn-Pb (Cu, Ag) vein deposit. An extension-related Mesozoic vein system in the High Atlas of Morocco. Structural, mineralogical, and geochemical evidence

Science.gov (United States)

Bouabdellah, M.; Beaudoin, G.; Leach, D.L.; Grandia, F.; Cardellach, E.

2009-01-01

The Assif El Mal Zn-Pb (Cu-Ag) vein system, located in the northern flank of the High Atlas of Marrakech (Morocco), is hosted in a Cambro-Ordovician volcaniclastic and metasedimentary sequence composed of graywacke, siltstone, pelite, and shale interlayered with minor tuff and mudstone. Intrusion of synorogenic to postorogenic Late Hercynian peraluminous granitoids has contact metamorphosed the host rocks giving rise to a metamorphic assemblage of quartz, plagioclase, biotite, muscovite, chlorite, amphibole, chloritoid, and garnet. The Assif El Mal Zn-Pb (Cu-Ag) mineralization forms subvertical veins with ribbon, fault breccia, cockade, comb, and crack and seal textures. Two-phase liquid-vapor fluid inclusions that were trapped during several stages occur in quartz and sphalerite. Primary inclusion fluids exhibit Th mean values ranging from 104??C to 198??C. Final ice-melting temperatures range from -8.1??C to -12.8??C, corresponding to salinities of ???15 wt.% NaCl equiv. Halogen data suggest that the salinity of the ore fluids was largely due to evaporation of seawater. Late secondary fluid inclusions have either Ca-rich, saline (26 wt.% NaCl equiv.), or very dilute (3.5 wt.% NaCl equiv.) compositions and homogenization temperatures ranging from 75??C to 150??C. The ??18O and ??D fluid values suggest an isotopically heterogeneous fluid source involving mixing between connate seawater and black-shale-derived organic waters. Low ??13CVPDB values ranging from -7.5??? to -7.7??? indicate a homogeneous carbon source, possibly organic matter disseminated in black shale hosting the Zn-Pb (Cu-Ag) veins. The calculated ??34SH2S values for reduced sulfur (22.5??? to 24.3???) are most likely from reduction of SO42- in trapped seawater sulfate or evaporite in the host rocks. Reduction of sulfate probably occurred through thermochemical sulfate reduction in which organic matter was oxidized to produce CO2 which ultimately led to precipitation of saddle dolomite with

Duplex scanning in the diagnosis of acute deep vein thrombosis of the lower extremity

NARCIS (Netherlands)

van Ramshorst, B.; Legemate, D. A.; Verzijlbergen, J. F.; Hoeneveld, H.; Eikelboom, B. C.; de Valois, J. C.; Meuwissen, O. J.

1991-01-01

In a prospective study the value of duplex scanning in the diagnosis of acute femoro-popliteal thrombosis was compared to conventional contrast venography (CV) as a gold standard. A total of 126 legs in 117 patients suspected of having deep vein thrombosis (DVT) or pulmonary embolism (PE) were

Effective antibodies immobilization and functionalized nanoparticles in a quartz-crystal microbalance-based immunosensor for the detection of parathion.

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Bartolomeo Della Ventura

Full Text Available Biosensor-based detection provides a rapid and low-cost alternative to conventional analytical methods for revealing the presence of the contaminants in water as well as solid matrices. Although important to be detected, small analytes (few hundreds of Daltons are an issue in biosensing since the signal they induce in the transducer, and specifically in a Quartz-Crystal Microbalance, is undetectable. A pesticide like parathion (M = 292 Da is a typical example of contaminant for which a signal amplification procedure is desirable.The ballasting of the analyte by gold nanoparticles has been already applied to heavy target as proteins or bacteria to improve the limit of detection. In this paper, we extend the application of such a method to small analytes by showing that once the working surface of a Quartz-Crystal Microbalance (QCM has been properly functionalized, a limit of detection lower than 1 ppb is reached for parathion. The effective surface functionalization is achieved by immobilizing antibodies upright oriented on the QCM gold surface by a simple photochemical technique (Photonic Immobilization Technique, PIT based on the UV irradiation of the antibodies, whereas a simple protocol provided by the manufacturer is applied to functionalize the gold nanoparticles. Thus, in a non-competitive approach, the small analyte is made detectable by weighing it down through a "sandwich protocol" with a second antibody tethered to heavy gold nanoparticles. The immunosensor has been proved to be effective against the parathion while showing no cross reaction when a mixture of compounds very similar to parathion is analyzed.The immunosensor described in this paper can be easily applied to any small molecule for which polyclonal antibodies are available since both the functionalization procedure of the QCM probe surface and gold nanoparticle can be applied to any IgG, thereby making our device of general application in terms of target analyte.

Visualization of red-ox proteins on the gold surface using enzymatic polypyrrole formation

International Nuclear Information System (INIS)

Ramanaviciene, A.; Kausaite-Minkstimiene, A.; Voronovic, J.; Ramanavicius, A.; Oztekin, Y.; Carac, G.; German, N.

2011-01-01

We describe a new method for the visualization of the activity of red-ox proteins on a gold interface. Glucose oxidase was selected as a model system. Surfaces were modified by adhesion of glucose oxidase on (a) electrochemically cleaned gold; (b) gold films modified with gold nanoparticles, (c) a gold surface modified with self-assembled monolayer, and (d) covalent immobilization of protein on the gold surface modified with a self-assembled monolayer. The simple optical method for the visualization of enzyme on the surfaces is based on the enzymatic formation of polypyrrole. The activity of the enzyme was quantified via enzymatic formation of polypyrrole, which was detected and investigated by quartz microbalance and amperometric techniques. The experimental data suggest that the enzymatic formation of the polymer may serve as a method to indicate the adhesion of active redox enzyme on such surfaces. (author)

Impact of Laser Fiber Design on Outcome of Endovenous Ablation of Lower-Extremity Varicose Veins: Results from a Single Practice

International Nuclear Information System (INIS)

Prince, Ethan A.; Soares, Gregory M.; Silva, MaryLou; Taner, Anil; Ahn, SunHo; Dubel, Gregory J.; Jay, Bryan S.

2011-01-01

The design of laser fibers used for endovenous laser ablation (EVLA) in the management of lower-extremity varicose vein disease may affect treatment success. The purpose of this investigation is to report our experience using the gold-tip NeverTouch VenaCure laser fiber (AngioDynamics, Queensbury, NY) and to compare that to our experience with standard bare-tip fibers. A retrospective chart review of 363 consecutive EVLA treatments using the gold-tip laser fiber was performed. Demographic data including patient age, sex, history of previous varicose vein stripping, vein identity, laterality, treatment length, total applied energy in joules (J), use of adjuvant sclerotherapy and ambulatory phlebectomy, treatment-related complications, and treatment failure, which was defined as recanalization of any portion of the treated vein during follow-up as assessed by duplex ultrasound examination―were entered into a spreadsheet. These data were compared with a control group of 471 EVLA treatments performed with a standard bare-tip laser fiber. Data were analyzed using independent-samples Student’s t test, chi-square test, and multivariate analysis. Demographic data were similar between the two groups. Treatments with the gold-tip fiber had a failure rate of 11.1%, whereas treatment with a bare-tip fiber had a failure rate of 2.3% during a similar follow-up period. This difference was highly statistically significant (p < 0.0001). Multivariate analysis showed fiber type as the most significant factor associated with treatment failure. We conclude that laser fiber design has a significant effect on treatment success in the performance of EVLA.

Quartz Crystal Microbalance Coated with Sol-gel-derived Thin Films as Gas Sensor for NO Detection

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S. J. O’Shea

2003-10-01

Full Text Available This paper presents the possibilities and properties of Indium tin oxide (ITO-covered quartz crystal as a NOx toxic gas-sensor. The starting sol-gel solution was prepared by mixing indium chloride dissolved in acetylacetone and tin chloride dissolved in ethanol (0-20% by weight. The ITO thin films were deposited on the gold electrodes of quartz crystal by spin-coating technique and subsequently followed a standard photolithography to pattern the derived films to ensure all sensors with the same sensing areas. All heat treatment processes were controlled below 500°C in order to avoid the piezoelectric characteristics degradation of quartz crystal (Quartz will lose its piezoelectricity at ~573°C due to the phase change from α to β. The electrical and structural properties of ITO thin films were characterized with Hall analysis system, TG/DTA, XRD, XPS, SEM and etc. The gas sensor had featured with ITO thin films of ~100nm as the receptor to sense the toxic gas NO and quartz crystal with frequency of 10MHz as the transducer to transfer the surface reactions (mass loading, etc into the frequency shift. A homemade setup had been employed to measure the sensor response under the static mode. The experimental results had indicated that the ITO-coated QCM had a good sensitivity for NO gas, ~12Hz/100ppm within 5mins. These results prove that the ITO-covered quartz crystals are usable as a gas sensor and as an analytical device.

Gold grade variation and particle microchemistry in exploration pits of the Batouri gold district, SE Cameroon

Science.gov (United States)

Vishiti, A.; Suh, C. E.; Lehmann, B.; Egbe, J. A.; Shemang, E. M.

2015-11-01

The Batouri area hosts lode-gold mineralization under several-m-thick lateritic cover. Pitting to bed rock on a geochemical Au anomaly defined from previous reconnaissance soil sampling identified five horizons ranging from saprock at the base to laterite at the top. Analysis of bulk samples from each horizon by fire assay shows that most of the horizons are barren although 119 ppb and 48 ppb Au values were obtained from one laterite horizon and one saprolite horizon, respectively, from two separate pits. All the horizons were panned and particulate gold was also recovered only from these two horizons. The gold grains from both horizons are morphologically and compositionally indistinguishable with rare quartz, pyrite and galena inclusions. The grains have irregular, sub-rounded, bean to elongated shapes and they show a remarkable core-rim zonation. Electron microprobe analysis of the grains recorded high gold content in the rims (86.3-100 wt%) and along fissures within the grains (95.1-100 wt%). The cores are relatively Ag rich (11.8-14 wt% Ag) while the rims (0.63-13.7 wt% Ag, most of the values fall within the lower limit of this range) and fissures (0.03-5.02 wt% Ag) are poor in Ag. The low Ag concentration in the rims and along fissures is attributed to preferential leaching of Ag; a process recognized in gold grains and platiniferous alloys from alluvia. The core composition of the grains is similar to that of primary gold composition in the bedrock. These results show that gold in the soil is relic particulate gold derived from the primary source with no evidence of secondary gold precipitation in the weathering cycle. In all the pits no horizon was systematically enriched in gold suggesting there has been no chemical remobilization of gold in this environment. Rather the dispersion of gold here is in the particulate form. Therefore combining particulate gold features with assay data is relevant to exploration in such tropical environments.

Pelvic Vein Embolisation in the Management of Varicose Veins

International Nuclear Information System (INIS)

Ratnam, Lakshmi A.; Marsh, Petra; Holdstock, Judy M.; Harrison, Charmaine S.; Hussain, Fuad F.; Whiteley, Mark S.; Lopez, Anthony

2008-01-01

Pelvic vein incompetence is common in patients with atypical varicose veins, contributing to their recurrence after surgery. Therefore, refluxing pelvic veins should be identified and treated. We present our experience with pelvic vein embolisation in patients presenting with varicose veins. Patients presenting with varicose veins with a duplex-proven contribution from perivulval veins undergo transvaginal duplex sonography (TVUS) to identify refluxing pelvic veins. Those with positive scans undergo embolisation before surgical treatment of their lower limb varicose veins. A total of 218 women (mean age of 46.3 years) were treated. Parity was documented in the first 60 patients, of whom 47 (78.3%) were multiparous, 11 (18.3%) had had one previous pregnancy, and 2 (3.3%) were nulliparous. The left ovarian vein was embolised in 78%, the right internal iliac in 64.7%, the left internal iliac in 56.4%, and the right ovarian vein in 42.2% of patients. At follow-up TVUS, mild reflux only was seen in 16, marked persistent reflux in 6, and new reflux in 3 patients. These 9 women underwent successful repeat embolisation. Two patients experienced pulmonary embolisation of the coils, of whom 1 was asymptomatic and 1 was successfully retrieved; 1 patient had a misplaced coil protruding into the common femoral vein; and 1 patient had perineal thrombophlebitis. The results of our study showed that pelvic venous embolisation by way of a transjugular approach is a safe and effective technique in the treatment of pelvic vein reflux.

Geometallurgical Study of a Gravity Recoverable Gold Orebody

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Simon C. Dominy

2018-04-01

Full Text Available Sheeted vein gold deposits are often characterised by multiple sub-parallel veins and free-milling coarse gold. Inherent mineralisation heterogeneity results in grade and process parameter variability, which increases project risk if not quantified. Measured grade variability is often exacerbated by poorly designed sampling and testwork protocols. Protocols that are optimised within the framework of the Theory of Sampling (TOS to suit the ore type, together with quality assurance/quality control systems, will reduce variability and provide fit-for-purpose results. Geometallurgy can be broadly split into two key approaches: strategic and tactical (or operational. The strategic approach focuses on the whole orebody and long-term life-of-mine view, whereas tactical geometallurgy relates to a more short- to medium-term view during mining. The geometallurgical approach requires spatially distributed samples within a deposit to support variability modelling. Diverse attributes from core logging, mineralogical/textural determination and small-scale tests are used to measure variability. This contribution presents a case study that emphasises an early-stage strategic geometallurgical programme applied to a gravity recoverable gold (GRG dominated deposit. It exemplifies how data can be acquired from a well-designed and planned programme to support resource estimation, a pre-feasibility study, trial mining and fast-track to production. A tactical geometallurgical programme is embedded into the mine operation.

Electrochemical and surface characterisation of carbon-film-coated piezoelectric quartz crystals

International Nuclear Information System (INIS)

Pinto, Edilson M.; Gouveia-Caridade, Carla; Soares, David M.; Brett, Christopher M.A.

2009-01-01

The electrochemical properties of carbon films, of thickness between 200 and 500 nm, sputter-coated on gold- and platinum-coated 6 MHz piezoelectric quartz crystal oscillators, as new electrode materials have been investigated. Comparative studies under the same experimental conditions were performed on bulk electrodes. Cyclic voltammetry was carried out in 0.1 M KCl electrolyte solution, and kinetic parameters of the model redox systems Fe(CN) 6 3-/4- and [Ru(NH 3 ) 6 ] 3+/2+ as well as the electroactive area of the electrodes were obtained. Atomic force microscopy was used in order to examine the surface morphology of the films, and the properties of the carbon films and the electrode-solution interface were studied by electrochemical impedance spectroscopy. The results obtained demonstrate the feasibility of the preparation and development of nanometer thick carbon film modified quartz crystals. Such modified crystals should open up new opportunities for the investigation of electrode processes at carbon electrodes and for the application of electrochemical sensing associated with the EQCM.

Two-photon imaging of field enhancement by groups of gold nanostrip antennas

DEFF Research Database (Denmark)

Novikov, Sergey M.; Beermann, Jonas; Sondergaard, Thomas

2009-01-01

Resonant field enhancement by groups of 16 nm thin gold nanostrip antennas consisting of four strips (widths of 70, 100, and 130 nm) and fixed gap (50, 100, 150, or 200 nm) between them and positioned on a quartz substrate is investigated by reflection spectroscopy and two-photon photoluminescenc...

Multistage crack seal vein and hydrothermal Ni enrichment in serpentinized ultramafic rocks (Koniambo massif, New Caledonia)

Science.gov (United States)

Cathelineau, Michel; Myagkiy, Andrey; Quesnel, Benoit; Boiron, Marie-Christine; Gautier, Pierre; Boulvais, Philippe; Ulrich, Marc; Truche, Laurent; Golfier, Fabrice; Drouillet, Maxime

2017-10-01

Sets of fractures and breccia sealed by Ni-rich silicates and quartz occur within saprock of the New Caledonian regolith developed over ultramafic rocks. The crystallization sequence in fractures is as follows: (1) serpentine stage: lizardite > polygonal serpentine > white lizardite; (2) Ni stage: Ni-Mg kerolite followed by red-brown microcrystalline quartz; and (3) supergene stages. The red-brown microcrystalline quartz corresponds to the very last stage of the Ni sequence and is inferred to have precipitated within the 50-95 °C temperature range. It constitutes also the main cement of breccia that has all the typical features of hydraulic fracturing. The whole sequence is therefore interpreted as the result of hydrothermal fluid circulation under medium to low temperature and fluctuating fluid pressure. Although frequently described as the result of a single downward redistribution of Ni and Mg leached in the upper part of the regolith under ambient temperature, the Ni silicate veins thus appear as the result of recurrent crack and seal process, corresponding to upward medium temperature fluid convection, hydraulic fracturing and subsequent fluid mixing, and mineral deposition.

The Porgera gold deposit, Papua, New Guinea, 2: sources of metals

International Nuclear Information System (INIS)

Richards, J.P.; McCulloch, M.T.; Kerrich, R.

1991-01-01

Sr and Pb isotopic studies of mineralized rocks and veins from the Porgera gold deposit indicates that these components were derived from a mixture of sedimentary and igneous sources, probably located within the Om Formation which underlies (< 3 km depth) the presently exposed Porgera Intrusive Complex (PIC) and associated ore deposit. Gold abundances in least-altered samples correlate with PGE, and indicate that the parental magma was mil enriched in Au and Pt-group elements relative to the Ir-group. (author)

Hydrogen speciation in synthetic quartz

Science.gov (United States)

Aines, R.D.; Kirby, S.H.; Rossman, G.R.

1984-01-01

The dominant hydrogen impurity in synthetic quartz is molecular H2O. H-OH groups also occur, but there is no direct evidence for the hydrolysis of Si-O-Si bonds to yield Si-OH HO-Si groups. Molecular H2O concentrations in the synthetic quartz crystals studied range from less than 10 to 3,300 ppm (H/Si), and decrease smoothly by up to an order of magnitude with distance away from the seed. OH- concentrations range from 96 to 715 ppm, and rise smoothly with distance away from the seed by up to a factor of three. The observed OH- is probably all associated with cationic impurities, as in natural quartz. Molecular H2O is the dominant initial hydrogen impurity in weak quartz. The hydrolytic weakening of quartz may be caused by the transformation H2O + Si-O-Si ??? 2SiOH, but this may be a transitory change with the SiOH groups recombining to form H2O, and the average SiOH concentration remaining very low. Synthetic quartz is strengthened when the H2O is accumulated into fluid inclusions and cannot react with the quartz framework. ?? 1984 Springer-Verlag.

Detrital zircon without detritus: a result of 496-Ma-old fluid-rock interaction during the gold-lode formation of Passagem, Minas Gerais, Brazil

Science.gov (United States)

Cabral, Alexandre Raphael; Zeh, Armin

2015-01-01

Zircon and xenotime occur in tourmaline-rich hydrothermal pockets in the auriferous lode of Passagem de Mariana, a world-class gold deposit. Zircon grains show pristine oscillatory zoning, but many of them are altered, exhibiting porous domains filled with graphite. Uranium-Pb dating of zircon, using in-situ laser ablation-inductively coupled plasma-mass spectrometry, yields ages between 3.2 and 2.65 Ga, which match those for detrital zircon of the footwall quartzite of the > 2.65-Ga-old Moeda Formation. Discordant analyses point to zircon-age resetting during the Brasiliano orogeny at ca. 500 Ma. This interpretation is supported by U-Pb dating of euhedral xenotime immediately adjacent to altered zircon within the same tourmaline pocket. The xenotime grains give a Concordia age of 496.3 ± 2.0 Ma, which is identical to that determined for monazite of a quartz-hematite vein-type deposit (i.e., jacutinga lode) in the region (Itabira), another important mineralisation style of gold. The occurrence of relatively abundant inherited detrital zircon, but absence of rock fragments in the tourmaline pocket investigated here, implies that detrital material was completely replaced by tourmaline. The graphite overprint on the altered detrital zircon attests to a reducing fluid, which was likely formed by fluid-rock interaction with carbonaceous phyllite of the Batatal Formation, the host rock of the Passagem lode.

Portuguese granites associated with Sn-W and Au mineralizations

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Ana M.R. Neiva

2002-01-01

Full Text Available In northern and central Portugal, there are different tin-bearing granites. Most of them are of S-type, others have mixed characteristics of I-type and S-type granites and a few are of I-type. Tin-tungsten deposits are commonly associated with Hercynian tin-bearing S-type granites. Some quartz veins with wolframite are associated with an I-type granite, which has a low Sn content. In suites of tin-bearing S-type granitic rocks, Sn content increases as a function of the degree of fractional crystallization. Greisenizations of two-mica S-type granites associated with tin-tungsten mineralizations are accompanied by an increase in SiO2, H2O+, Sn, W, Nb, Ta, Rb, Zn, and Pb and decrease in MgO, Na2O, V, Sc,Zr, and Sr. The granite associated with the Jales gold deposit is of S-type and strongly differentiated like the tin-bearing S-type granites, but it has a very low Sn content. During fractional crystallization, Si, Rb, Sn, Pb, Au, As, Sb, and S increase. During increasing degree of hydrothermal alteration of this granite at the gold-quartz vein walls, there are progressive increases in K2O, H2O+, Sn, Cs, Cu, Pb, Au, Sb, As, and S.

Quartz fiber calorimeter

International Nuclear Information System (INIS)

Akchurin, N.; Doulas, S.; Ganel, O.; Gershtein, Y.; Gavrilov, V.; Kolosov, V.; Kuleshov, S.; Litvinsev, D.; Merlo, J.-P.; Onel, Y.; Osborne, D.; Rosowsky, A.; Stolin, V.; Sulak, L.; Sullivan, J.; Ulyanov, A.; Wigmans, R.; Winn, D.

1996-01-01

A calorimeter with optical quartz fibers embedded into an absorber matrix was proposed for the small angle region of the CMS detector at LHC (CERN). This type of calorimeter is expected to be radiation hard and to produce extremely fast signal. Some results from beam tests of the quartz fiber calorimeter prototype are presented. (orig.)

Controlled adsorption of cytochrome c to nanostructured gold surfaces

International Nuclear Information System (INIS)

Gomes, Inês; Feio, Maria J.; Santos, Nuno C.; Eaton, Peter; Serro, Ana Paula; Saramago, Benilde; Pereira, Eulália; Franco, Ricardo

2012-01-01

Controlled electrostatic physisorption of horse heart cytochrome c (Cyt c) onto nanostructured gold surfaces was investigated using Quartz-Crystal Microbalance measurements in planar gold surfaces with or without functionalization using a self-assembled monolayer (SAM) of the alkanethiol mercaptoundecanoic acid (MUA). MUA is a useful functionalization ligand for gold surfaces, shedding adsorbed biomolecules from the excessive electron density of the metal. A parallel analysis was conducted in the corresponding curved surfaces of 15 nm gold nanoparticles (AuNPs), using zeta-potential and UV– visible spectroscopy. Atomic Force Microscopy of both types of functionalized gold surfaces with a MUA SAM, allowed for visualization of Cyt c deposits on the nanostructured gold surface. The amount of Cyt c adsorbed onto the gold surface could be controlled by the solution pH. For the assays conducted at pH 4.5, when MUA SAM- functionalized planar gold surfaces are positive or neutral, and Cyt c has a positive net charge, only 13 % of the planar gold surface area was coated with protein. In contrast, at pH 7.4, when MUA SAM-functionalized planar gold surfaces and Cyt c have opposite charges, a protein coverage of 28 % could be observed implying an adsorption process strongly governed by electrostatic forces. Cyt c adsorption on planar and curved gold surfaces are found to be greatly favored by the presence of a MUA-capping layer. In particular, on the AuNPs, the binding constant is three times larger than the binding constant obtained for the original citrate-capped AuNPs.

Controlled adsorption of cytochrome c to nanostructured gold surfaces

Energy Technology Data Exchange (ETDEWEB)

Gomes, Ines [Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, REQUIMTE, Departamento de Quimica (Portugal); Feio, Maria J. [Faculdade de Ciencias da Universidade do Porto, REQUIMTE, Departamento de Quimica e Bioquimica (Portugal); Santos, Nuno C. [Faculdade de Medicina da Universidade de Lisboa, Instituto de Medicina Molecular (Portugal); Eaton, Peter [Faculdade de Ciencias da Universidade do Porto, REQUIMTE, Departamento de Quimica e Bioquimica (Portugal); Serro, Ana Paula; Saramago, Benilde [Centro de Quimica Estrutural, Instituto Superior Tecnico (Portugal); Pereira, Eulalia [Faculdade de Ciencias da Universidade do Porto, REQUIMTE, Departamento de Quimica e Bioquimica (Portugal); Franco, Ricardo, E-mail: ricardo.franco@fct.unl.pt [Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, REQUIMTE, Departamento de Quimica (Portugal)

2012-12-15

Controlled electrostatic physisorption of horse heart cytochrome c (Cyt c) onto nanostructured gold surfaces was investigated using Quartz-Crystal Microbalance measurements in planar gold surfaces with or without functionalization using a self-assembled monolayer (SAM) of the alkanethiol mercaptoundecanoic acid (MUA). MUA is a useful functionalization ligand for gold surfaces, shedding adsorbed biomolecules from the excessive electron density of the metal. A parallel analysis was conducted in the corresponding curved surfaces of 15 nm gold nanoparticles (AuNPs), using zeta-potential and UV- visible spectroscopy. Atomic Force Microscopy of both types of functionalized gold surfaces with a MUA SAM, allowed for visualization of Cyt c deposits on the nanostructured gold surface. The amount of Cyt c adsorbed onto the gold surface could be controlled by the solution pH. For the assays conducted at pH 4.5, when MUA SAM- functionalized planar gold surfaces are positive or neutral, and Cyt c has a positive net charge, only 13 % of the planar gold surface area was coated with protein. In contrast, at pH 7.4, when MUA SAM-functionalized planar gold surfaces and Cyt c have opposite charges, a protein coverage of 28 % could be observed implying an adsorption process strongly governed by electrostatic forces. Cyt c adsorption on planar and curved gold surfaces are found to be greatly favored by the presence of a MUA-capping layer. In particular, on the AuNPs, the binding constant is three times larger than the binding constant obtained for the original citrate-capped AuNPs.

Lectin typing of Campylobacter jejuni using a novel quartz crystal microbalance technique

Energy Technology Data Exchange (ETDEWEB)

Yakovleva, Maria E., E-mail: maria.yakovleva@gmail.com [Department of Infectious Diseases and Medical Microbiology, Lund University, 223 62 Lund (Sweden); Moran, Anthony P. [Department of Microbiology, School of Natural Sciences, National University of Ireland, Galway (Ireland); Safina, Gulnara R. [Department of Analytical and Marine Chemistry, University of Gothenburg, 412 96 Gothenburg (Sweden); Wadstroem, Torkel [Department of Infectious Diseases and Medical Microbiology, Lund University, 223 62 Lund (Sweden); Danielsson, Bengt [Acromed Invest AB, Magistratsvaegen 10, 226 43 Lund (Sweden)

2011-05-23

Seven Campylobacter jejuni strains were characterised by a lectin typing assay. The typing system was based on a quartz crystal microbalance technique (QCM) with four commercially available lectins (wheat germ agglutinin, Maackia amurensis lectin, Lens culinaris agglutinin, and Concanavalin A), which were chosen for their differing carbohydrate specificities. Initially, the gold surfaces of the quartz crystals were modified with 11-mercaptoundecanoic acid followed by lectin immobilisation using a conventional amine-coupling technique. Bacterial cells were applied for lectin typing without preliminary treatment, and resonant frequency and dissipation responses were recorded. The adhesion of microorganisms on lectin surfaces was confirmed by atomic force microscopy. Scanning was performed in the tapping mode and the presence of bacteria on lectin-coated surfaces was successfully demonstrated. A significant difference in the dissipation response was observed for different C. jejuni strains which made it possible to use this parameter for discriminating between bacterial strains. In summary, the QCM technique proved a powerful tool for the recognition and discrimination of C. jejuni strains. The approach may also prove applicable to strain discrimination of other bacterial species, particularly pathogens.

Lectin typing of Campylobacter jejuni using a novel quartz crystal microbalance technique

International Nuclear Information System (INIS)

Yakovleva, Maria E.; Moran, Anthony P.; Safina, Gulnara R.; Wadstroem, Torkel; Danielsson, Bengt

2011-01-01

Seven Campylobacter jejuni strains were characterised by a lectin typing assay. The typing system was based on a quartz crystal microbalance technique (QCM) with four commercially available lectins (wheat germ agglutinin, Maackia amurensis lectin, Lens culinaris agglutinin, and Concanavalin A), which were chosen for their differing carbohydrate specificities. Initially, the gold surfaces of the quartz crystals were modified with 11-mercaptoundecanoic acid followed by lectin immobilisation using a conventional amine-coupling technique. Bacterial cells were applied for lectin typing without preliminary treatment, and resonant frequency and dissipation responses were recorded. The adhesion of microorganisms on lectin surfaces was confirmed by atomic force microscopy. Scanning was performed in the tapping mode and the presence of bacteria on lectin-coated surfaces was successfully demonstrated. A significant difference in the dissipation response was observed for different C. jejuni strains which made it possible to use this parameter for discriminating between bacterial strains. In summary, the QCM technique proved a powerful tool for the recognition and discrimination of C. jejuni strains. The approach may also prove applicable to strain discrimination of other bacterial species, particularly pathogens.

Prospects of gold mineralization in the Gilgit-Baltistan Province of Pakistan

Science.gov (United States)

Shah, M. T.; Khan, S. D.; Tahirkheli, T.; Ahmad, L.; Miandad, S.; Rehman, A. U.; Ali, L.

2012-12-01

mainly pyrite and chalcopyrite with subordinate amount of bornite and tetrahedrite. Surface leaching of these phases to malachite, azurite and limonite is common. Quartz veining, silicification, carbonization and at places brecciation are the common features of these alteration zones. The concentrations of gold were found in the range of 3ppb to 112ppb, of Golo Das, Bagrot valley, Shigri Bala, Machulu and Ranthak areas respectively. The barren rock samples have generally of the multi-times enrichment of gold in the alteration zones. The sulfide mineralization along with gold in the alteration zones could be attributed to the hydrothermal/epithermal activity involving meteoric, igneous and or metamorphic fluid individually or mixture of these. The occurrence of dioritic intrusions (igneous fluid source) and the transitional dilated zones (metamorphic fluid source) on the major reactivated thrust fault (i.e., NSZ) in the vicinity of these alteration zones strengthen these observations. However, isotopic studies are underway to solve this problem. This study suggests that the alteration zones in the studied areas have the potential to be explored in detail for possible economical gold mineralization.

The Berezitovoe gold-polymetallic deposit (Upper Amur region, Russia: Structure, mineralogy and genetic aspects

Directory of Open Access Journals (Sweden)

Alexandr S. Vakh

2016-05-01

Full Text Available The Berezitovoe deposit in the Sergachi volcano-plutonic and metallogenic belt preserves evidence for polymetallic mineralization of multiple stages. The steeply dipping garnet-tourmaline-muscovite-quartz metasomatites (with K-Ar ages of 132 ± 2.9 and 127 ± 4.4 Ma carry two distinct stages of mineralization developed at different times: (1 polymetallic mineralization and (2 gold-quartz. The deposit is located within Paleozoic gneissose granitoids of the Pikansky complex (dated as 379 ± 1.1 Ma by zircon U-Pb method intruded by early Cretaceous porphyry-like granites of the Haikta pluton (dated as 137 ± 0.67 Ma by zircon U-Pb method and late Cretaceous dikes of porphyrites, porphyries, and lamprophyres. Evidence suggests the action of late gold-bearing hydrothermal fluids on the early polymetallic ores and the selective mobilization of some elements from these lead to redeposition together with complex sulphosalts.

Influence of the graphene substrate on morphology of the gold thin film. Spectroscopic ellipsometry study

International Nuclear Information System (INIS)

Kostruba, A.M.

2013-01-01

In metal optics gold assumes a special status because of its practical importance in optoelectronic and nanooptical devices, and its role huge increases when occurs combination of gold with two-dimension materials. We performed spectroscopic ellipsometry measurements on evaporated gold, and gold–graphene nanostructures to determine the optical dielectric function across a broad spectral range from 250 to 1000 nm. It was found that the deposition of gold film on the quartz substrate covered by graphene flake leads to significant changes in structural and dielectric properties of thin gold layer. Such changes can be explained by increasing of the gold cluster size. The model fit of the ellipsometric data demonstrates that the bilayer “graphene-gold” nanostructure can be described as a uniform optically homogeneous layer with modified optical properties. We can suggest that graphene flake creates a matrix for epitaxial alignment of the crystalline structure of the gold film during its growing. Effective doping of the graphene by free electrons of the gold clusters tends to decrease the optical contrast at the graphene-gold interface.

Varicose vein stripping

Science.gov (United States)

... stripping; Venous reflux - vein stripping; Venous ulcer - veins Patient Instructions Surgical wound care - open Varicose veins - what to ask your doctor Images Circulatory system References American Family Physician. Management of varicose veins. www.aafp.org/afp/2008/ ...

The problem of dating quartz 2: Synchrotron generated X-ray excited optical luminescence (XEOL) from quartz

International Nuclear Information System (INIS)

King, G.E.; Finch, A.A.; Robinson, R.A.J.; Taylor, R.P.; Mosselmans, J.F.W.

2011-01-01

The luminescence emission of quartz is used in optically stimulated luminescence dating (OSL), however the precise origins of the emission are unclear. A suite of quartz samples were analysed using X-ray excited optical luminescence (XEOL). Radiation dose effects were observed whereby the UV emissions (3.8 and 3.4 eV) were depleted to the benefit of the red emission (1.9-2.0 eV). Samples were excited at ∼7 keV. Understanding why some quartz emit light more brightly than others will increase the efficiency and precision of OSL analyses. - Highlights: → The X-ray excited optical luminescence (XEOL) emission of quartz is explored. → The XEOL of quartz of different provenances varies. → Radiation dosing causes UV emissions to deplete to the benefit of red emissions. → The 3.8 and 3.4 eV emissions deplete at the same rate. → The quartz luminescence emission exhibits anisotropic effects.

Quartz analysis in gravimetric sampling

International Nuclear Information System (INIS)

Rex, D.A.

1990-01-01

An overview of the methods employed in the assessment of quartz exposure is provided. The principles and some of the problems associated with each method is discussed. The methods reviewed include wet chemical methods, X-ray diffraction and infrared absorption of which the latter two methods are deemed appropriate for analysing quartz on personal gravimetric collected samples. The implications of combining area samples collected over a six month period, and performing only a single quartz analysis rather than separate analyses, are considered. Finally, various options open to mines with regard to their involvement with quartz analysis are also briefly discussed. 35 refs., 6 figs., 1 tab

Radiation-Hard Quartz Cerenkov Calorimeters

International Nuclear Information System (INIS)

Akgun, U.; Onel, Y.

2006-01-01

New generation hadron colliders are going to reach unprecedented energies and radiation levels. Quartz has been identified as a radiation-hard material that can be used for Cerenkov calorimeters of the future experiments. We report from the radiation hardness tests performed on quartz fibers, as well as the characteristics of the quartz fiber and plate Cerenkov calorimeters that have been built, designed, and proposed for the CMS experiment

Theoretical analysis of gold nano-strip gap plasmon resonators

Energy Technology Data Exchange (ETDEWEB)

Soendergaard, T; Jung, J; Bozhevolnyi, S I; Della Valle, G [Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg Oest (Denmark)], E-mail: ts@nano.aau.dk

2008-10-15

Gold gap plasmon resonators consisting of two nm-thin and sub-micron-wide gold strips separated by a nm-thin air or quartz gap are considered. Scattering resonances and resonant fields are related to a model of resonances being due to counter-propagating gap plasmon polaritons forming standing waves. A small gap ({approx}10 nm) is found to result in small resonance peaks in scattering spectra but large electric field magnitude enhancement ({approx}20), whereas a large gap ({approx}100 nm) is found to result in more pronounced scattering peaks but smaller field enhancement. Design curves are presented that allow construction of gap plasmon resonators with any desired resonance wavelength in the range from the visible to the infrared, including telecom wavelengths. The relation between resonance wavelength and resonator width is close to being linear. The field magnitude enhancement mid between the gold strips is systematically investigated versus gap size and wavelength.

Portal Vein Thrombosis

Directory of Open Access Journals (Sweden)

Hakan Demirci

2016-01-01

Full Text Available Portal vein thrombosis is an important cause of presinusoidal portal hypertension. Portal vein thrombosis commonly occurs in patient with cirrhosis, malignancy and prothrombotic states. Patients with acute portal vein thrombosis have immediate onset. Patients with chronic portal vein thrombosis have developed portal hypertension and cavernous portal transformation. Portal vein thrombosis is diagnosed with doppler ultrasound, computed tomography and magnetic resonance imaging. Therapy with low molecular weight heparin achieves recanalization in more than half of acute cases.

Collateral veins in left renal vein stenosis demonstrated via CT

Energy Technology Data Exchange (ETDEWEB)

Lien, H.H.; Lund, G.; Talle, K.

1983-02-01

Twelve patients with left renal vein stenosis from tumor compression were studied with CT. All had distended collateral veins in the perirenal space which either formed a radiating or a cobweb pattern or appeared as marked longitudinal veins. Inferior phrenic vein branches were seen in seven patients and were considerably enlarged in two. Other major veins possibly taking part in collateral circulation could not be recognized due to obliteration of fat planes. The renal fascia was thickened in eleven patients, probably due to edema. A close study of the perirenal space with CT may give valuable information about collateral development.

Collateral veins in left renal vein stenosis demonstrated via CT

International Nuclear Information System (INIS)

Lien, H.H.; Lund, G.; Talle, K.

1983-01-01

Twelve patients with left renal vein stenosis from tumor compression were studied with CT. All had distended collateral veins in the perirenal space which either formed a radiating or a cobweb pattern or appeared as marked longitudinal veins. Inferior phrenic vein branches were seen in seven patients and were considerably enlarged in two. Other major veins possibly taking part in collateral circulation could not be recognized due to obliteration of fat planes. The renal fascia was thickened in eleven patients, probably due to edema. A close study of the perirenal space with CT may give valuable information about collateral development. (orig.)

Characterisation of airborne dust in a gold mine

International Nuclear Information System (INIS)

Annegarn, H.J.; Symons, G.; Zucchiatti, A.; Booth-Jones, P.; Storms, H.

1984-01-01

Samples of airborne dust were collected from a gold mine using a single orifice cascade impactor. The size fractionated dust samples were analysed by Particle Induced X-ray Emission (PIXE) and Electron Probe X-ray Micro-Analysis (EPXMA). Results on chemical composition of the sub-micron, inhalable dust were obtained. In addition ot quartz dust, a large fraction consisted of chlorine containing particles. The filter grade efficiency of a spray cooling chamber was calculated as a function of particle size

Adrenal Vein Sampling for Conn's Syndrome: Diagnosis and Clinical Outcomes.

Science.gov (United States)

Deipolyi, Amy R; Bailin, Alexander; Wicky, Stephan; Alansari, Shehab; Oklu, Rahmi

2015-06-19

Adrenal vein sampling (AVS) is the gold standard test to determine unilateral causes of primary aldosteronism (PA). We have retrospectively characterized our experience with AVS including concordance of AVS results and imaging, and describe the approach for the PA patient in whom bilateral AVS is unsuccessful. We reviewed the medical records of 85 patients with PA and compared patients who were treated medically and surgically on pre-procedure presentation and post-treatment outcomes, and evaluated how technically unsuccessful AVS results were used in further patient management. Out of the 92 AVS performed in 85 patients, AVS was technically successful bilaterally in 58 (63%) of cases. Either unsuccessful AVS prompted a repeat AVS, or results from the contralateral side and from CT imaging were used to guide further therapy. Patients who were managed surgically with adrenalectomy had higher initial blood pressure and lower potassium levels compared with patients who were managed medically. Adrenalectomy results in significantly decreased blood pressure and normalization of potassium levels. AVS can identify surgically curable causes of PA, but can be technically challenging. When one adrenal vein fails to be cannulated, results from the contralateral vein can be useful in conjunction with imaging and clinical findings to suggest further management.

The geology, structure and mineralisation of the Oyu Tolgoi porphyry copper-gold-molybdenum deposits, Mongolia: A review

Directory of Open Access Journals (Sweden)

T.M. (Mike Porter

2016-05-01

Mineralisation is characterised by varying, telescoped stages of intrusion and alteration. Early A-type quartz veined dykes were followed by Cu-Au mineralisation associated with potassic alteration, mainly K-feldspar in quartz-monzodiorite and biotite-magnetite in basaltic hosts. Downward reflux of cooled, late-magmatic hydrothermal fluid resulted in intense quartz-sericite retrograde alteration in the upper parts of the main syn-mineral intrusions, and an equivalent chlorite-muscovite/illite-hematite assemblage in basaltic host rocks. Uplift, facilitated by syn-mineral longitudinal faulting, brought sections of the porphyry deposit to shallower depths, to be overprinted and upgraded by late stage, shallower, advanced argillic alteration and high sulphidation mineralisation. Key controls on the location, size and grade of the deposit cluster include (i a long-lived, narrow faulted corridor; (ii multiple pulses of overlapping intrusion within the same structure; and (iii enclosing reactive, mafic dominated wall rocks, focussing ore.

Gold and uranium occurrences in quartz - pebble conglomerate of Iron Ore Group, Bagiyabahal - Baratangra area, Sundargarh district, Odisha , India

International Nuclear Information System (INIS)

Jana, Ashim; Sarkar, B.C.; Kumar, Suresh; Kumar, Ajay; Yadav, G.S.; Kumar, Pramod

2016-01-01

India is deficient in both gold and uranium resources. Almost one-third of the annual global mine production of ∼2500 tonnes of gold is imported into India to fulfil the high gold consumption. Uranium is important for production of nuclear energy, more specifically to execute the country's ambitious programme to generate 20 GW of electricity by 2020

Predicting Cyanide Consumption in Gold Leaching: A Kinetic and Thermodynamic Modeling Approach

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Yaser Kianinia

2018-03-01

Full Text Available The consumption of cyanide during processing operations is a major economic cost in the extraction of gold from its ores, while the discharge of cyanide wastes may result in significant environmental pollution. Many factors influence the levels of consumption and discharge of cyanide, including ore mineralogy and lixiviant solution chemistry. This paper proposes a robust methodology to estimate leaching cyanide consumption due to oxidation and reactions with gold, chalcopyrite and pyrite minerals forming various cyanide complexes, cyanate, thiocyanate and hydroxide precipitates of copper and iron. The method involves concurrent modelling of both the oxidation and leaching kinetics of minerals and the chemical speciation of the lixiviant solutions. The model was calibrated by conducting cyanide leaching experiments on pyrite, chalcopyrite, pyrite + chalcopyrite, pyrite + chalcopyrite + gold and pyrite + chalcopyrite + gold + quartz systems and determining the total Cu, Fe, Au and CN− concentrations in solution. We show that this model can successfully estimate the formation of cyanide complexes and, hence, the consumption of cyanide.

Russian institute receives CMS Gold Award

CERN Multimedia

Patrice Loïez

2003-01-01

The Snezhinsk All-Russian Institute of Scientific Research for Technical Physics (VNIITF) of the Russian Federal Nuclear Centre (RFNC) is one of twelve CMS suppliers to receive awards for outstanding performance this year. The CMS Collaboration took the opportunity of the visit to CERN of the Director of VNIITF and his deputy to present the CMS Gold Award, which the institute has received for its exceptional performance in the assembly of steel plates for the CMS forward hadronic calorimeter. This calorimeter consists of two sets of 18 wedge-shaped modules arranged concentrically around the beam-pipe at each end of the CMS detector. Each module consists of steel absorber plates with quartz fibres inserted into them. The institute developed a special welding technique to assemble the absorber plates, enabling a high-quality detector to be produced at relatively low cost.RFNC-VNIITF Director Professor Georgy Rykovanov (right), is seen here receiving the Gold Award from Felicitas Pauss, Vice-Chairman of the CMS ...

Focus on Varicose Veins

Science.gov (United States)

... because the valves of the veins no longer work. Under the pressure of gravity these veins can continue to expand and, in ... and to determine whether the vein valves are work- ing properly or have ... painless. How are varicose veins treated? Varicose veins are always ...

Ultrasonographic analysis in vitro of parietal thickness of lower limb varicose veins.

Science.gov (United States)

Bruschi, E; Como, G; Zuiani, C; Segatto, E; Rocco, M; Biasi, G; Bazzocchi, M

2006-09-01

The aim of this study was to evaluate the ability of ultrasound (US) to measure the parietal thickness of varicose veins. In a blind in vitro analysis, 28 great saphenous veins, obtained after stripping surgery from 28 patients with chronic venous insufficiency, were examined with a digital US scanner ATL-HDI5000, linear 5-1 to 2-MHz broadband probe, compound imaging technique and analogic-digital zooming. We obtained one to three progressive measurements for each vein wall (total 67 parietal thicknesses). The samples, fixed in formalin, were sent to the pathology laboratory: sections were obtained at the same level of the sonographic planes, and images were obtained by digital camera mounted on an optical microscope. Measurements obtained at histology were considered as the gold standard. K-statistic was applied to compare sonographic and histologic measurements. Considering only the hypoechoic wall portion, 29/29 (100%) diagnoses of hypotrophy (K=0.91), 19/22 (86%) diagnoses of normotrophy (K=0,47) and 12/16 (75%) diagnoses of hypertrophy (K=0.7) were obtained by sonography. In our preliminary experience, the in vitro study of varicose veins allows precise, at least morphological, detection of hypotrophic walls. If these preliminary data are confirmed in vivo, sonography could be used to discriminate patients eligible for conservative treatment instead of surgery.

Quartz glass behavior at ultraviolet spectrum region

International Nuclear Information System (INIS)

Braga, A.F.B.; Barbosa, L.C.; Evora, C.A.P.D.

1990-01-01

Melted quartz ingots were produced from raw materials of different sources. Behavior studies of these three different quartz glass were made at the eletromagnetic spectrum ultraviolet region. The atomic absorption spectroscopy was used as an analysis technique of the alkaline, transition and aluminum metal traces. It was found that the alkaline, transition and aluminum metals impurities present a great influence on the melted quartz spectral behavior at the ultraviolet region. It was stated that measurments at this spectrum region constitute an important characterization technique to natural quartz as well as melted quartz. (author) [pt

Influences of Hydraulic Fracturing on Fluid Flow and Mineralization at the Vein-Type Tungsten Deposits in Southern China

Directory of Open Access Journals (Sweden)

Xiangchong Liu

2017-01-01

Full Text Available Wolframite is the main ore mineral at the vein-type tungsten deposits in the Nanling Range, which is a world-class tungsten province. It is disputed how wolframite is precipitated at these deposits and no one has yet studied the links of the mechanical processes to fluid flow and mineralization. Finite element-based numerical experiments are used to investigate the influences of a hydraulic fracturing process on fluid flow and solubility of CO2 and quartz. The fluids are aqueous NaCl solutions and fluid pressure is the only variable controlling solubility of CO2 and quartz in the numerical experiments. Significant fluctuations of fluid pressure and high-velocity hydrothermal pulse are found once rock is fractured by high-pressure fluids. The fluid pressure drop induced by hydraulic fracturing could cause a 9% decrease of quartz solubility. This amount of quartz deposition may not cause a significant decrease in rock permeability. The fluid pressure decrease after hydraulic fracturing also reduces solubility of CO2 by 36% and increases pH. Because an increase in pH would cause a major decrease in solubility of tungsten, the fluid pressure drop accompanying a hydraulic fracturing process facilitates wolframite precipitation. Our numerical experiments provide insight into the mechanisms precipitating wolframite at the tungsten deposits in the Nanling Range as well as other metals whose solubility is strongly dependent on pH.

Electrografting of N’,N’-dimethylphenothiazin-5-ium-3,7-diamine (Azure A) diazonium salt forming electrocatalytic organic films on gold or graphene oxide gold hybrid electrodes

International Nuclear Information System (INIS)

Gómez-Anquela, C.; Revenga-Parra, M.; Abad, J.M.; Marín, A. García; Pau, J.L.; Pariente, F.; Piqueras, J.; Lorenzo, E.

2014-01-01

Electroactive films containing redox active phenothiazine moieties are covalently bound onto gold and graphene oxide gold hybrid electrodes, using reductive redox grafting of N’,N’-dimethylphenothiazin-5-ium-3,7-diamine (Azure A) diazonium salt. The grafting procedure is based on continuous voltammetric potential sweep of solutions containing the phenothiazine diazonium salt previously generated in situ. Control of the film thickness, electroactivity and stability can easily be exerted through appropriate choice of the concentration and number of potential scans performed. Cyclic Voltammetry, Electrochemical Quartz Crystal Microbalance (EQCM) and Spectroscopic Ellipsometry are used to characterize the growth process as well as the viscoelastic properties of the resulting stable electrografted films. The electron transfer reactions through the films are mediated by the presence of the Azure A redox moieties, which show a quasi-reversible electrochemical response and exhibit a potent electrocatalytic effect toward the oxidation of NADH. This electrocatalytic model has been used to compare the properties of Azure A electrografted films generated on gold electrodes with those obtained on hybrid electrodes composed by graphene oxide modified gold electrodes

A single-centre experience of the implementation of adrenal vein sampling procedure: the impact on the diagnostic work-up in primary aldosteronism

NARCIS (Netherlands)

Kadziela, J.; Prejbisz, A.; Michalowska, I.; Kolodziejczyk-Kruk, S.; Schultze Kool, L.J.; Kabat, M.; Janaszek-Sitkowska, H.; Toutounchi, S.; Galazka, Z.; Ambroziak, U.; Bednarczuk, T.; Ptasinska-Wnuk, D.; Hoffmann, M.; Januszewicz, M.; Januszewicz, A.; Witkowski, A.

2017-01-01

BACKGROUND: Primary aldosteronism is one of the most common causes of secondary hypertension. Adrenal vein sampling (AVS) remains a "gold standard" procedure in differentiation between unilateral (adenoma) and bilateral (hyperplasia) disease. AIM: The aim of this study was to present our

Some Applications of X-Ray Based Elemental Analysis Methods for Romanian Gold Minerals Studies

International Nuclear Information System (INIS)

Stan, D.; Constantinescu, B.; Pauna, C.; Neacsu, A.; Popescu, G.

2009-01-01

The elemental composition of gold, gold minerals and gold associated minerals releases important information's both from scientific (geologic) and economic point of view. In the present work, we focused on samples from Rosia Montana and Musariu ore deposits, from so called T ransylvanian gold of the golden q uadrilateral , Metaliferi Mountains. Our investigation started using optical microscopy. On the sample from Rosia Montana native gold band could be macroscopically seen. Gold occurs also like native gold in carbonate minerals, or associated with galena, sphalerite, chalcopyrite and quartz. The sample from Musariu shows native gold distributed at the border of sphalerite, native gold enclosed and along the margins of sphalerite and native gold between quartz grains. Three X-ray (the emission of characteristic lines spectra for each element present in the sample) based elemental analysis methods were also used: X-Ray Fluorescence (XRF), micro Synchrotron Radiation induced X-Ray Fluorescence (micro-SR-XRF) and micro Proton Induced X-Ray Emission (micro-PIXE). Our XRF methods are based on Xray tube spectrometers: a portable one - X-MET 3000TX and a stationary one - Spectro MIDEX. The two Rosia Montana and Musariu gold samples were studied using the micro-PIXE technique at the AN2000 accelerator of Laboratory Nazionale di Legnaro (LNL), INFN, Italy - maps and point spectra. The experiment was carried out with a 2 MeV proton microbeam (9 μm 2 beam area), maximum beam current 400 pA. The characteristic X-rays were measured with a Canberra HPGe detector (with 180 eV FWHM at 5.9 keV). Complementary experiments on the samples due the improved condition offered by the high energy X-rays, namely -Sb, Sn, Te detection, were performed at BESSY Synchrotron Radiation Facility, Berlin - point spectra. During the experiment, point spectra were acquired at 35 keV, excitation energy, using a spatially resolved synchrotron-radiation XRF setup detected to analyses. The XRF

Transpressional folding and associated cross-fold jointing controlling the geometry of post-orogenic vein-type W-Sn mineralization: examples from Minas da Panasqueira, Portugal

Science.gov (United States)

Jacques, Dominique; Vieira, Romeu; Muchez, Philippe; Sintubin, Manuel

2018-02-01

The world-class W-Sn Panasqueira deposit consists of an extensive, subhorizontal vein swarm, peripheral to a late-orogenic greisen cupola. The vein swarm consists of hundreds of co-planar quartz veins that are overlapping and connected laterally over large distances. Various segmentation structures, a local zigzag geometry, and the occurrence of straight propagation paths indicate that they exploited a regional joint system. A detailed orientation analysis of the systematic joints reveals a geometrical relationship with the subvertical F2 fold generation, reflecting late-Variscan transpression. The joints are consistently orthogonal to the steeply plunging S0-S2 intersection lineation, both on the regional and the outcrop scale, and are thus defined as cross-fold or ac-joints. The joint system developed during the waning stages of the Variscan orogeny, when already uplifted to an upper-crustal level. Veining reactivated these cross-fold joints under the conditions of hydraulic overpressures and low differential stress. The consistent subperpendicular orientation of the veins relative to the non-cylindrical F2 hinge lines, also when having an inclined attitude, demonstrates that veining did not occur during far-field horizontal compression. Vein orientation is determined by local stress states variable on a meter-scale but with the minimum principal stress consistently subparallel to fold hinge lines. The conspicuous subhorizontal attitude of the Panasqueira vein swarm is thus dictated by the geometry of late-orogenic folds, which developed synchronous with oroclinal buckling of the Ibero-Armorican arc.

Adrenal vein sampling: substantial need for technical improvement at regional referral centres.

Science.gov (United States)

Elliott, Panda; Holmes, Daniel T

2013-10-01

Adrenal vein sampling (AVS) is the gold standard for localization of aldosterone producing adenoma. The anatomy of the right adrenal vein makes this procedure technically demanding and it may yield no clinical information if the adrenal veins are not adequately cannulated. Having frequently observed the technical failure of AVS, we undertook a review of 220 procedures in British Columbia, Canada. Subjects were retrospectively identified through the laboratory information system. The following were collected: demographics, screening aldosterone concentration and renin activity/mass, results of dynamic function tests, AVS aldosterone and cortisol results. Standard calculations were performed on AVS data and site-specific success rates were compared. The effect of adrenocorticotropin hormone (ACTH) stimulation on the selectivity index (SI) and lateralization index (LI) were explored. The overall technical success-rate of AVS procedures was only 44% in procedures where no ACTH-stimulation was used (n=200) but this rose significantly (psuccess of AVS is lower than reported elsewhere. Provided that effects on the LI are considered, the use of ACTH-stimulation during AVS assists in the identification of unilateral forms of PA. Copyright © 2013 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Spider Vein Removal

Science.gov (United States)

Spider veins: How are they removed? I have spider veins on my legs. What options are available ... M.D. Several options are available to remove spider veins — thin red lines or weblike networks of ...

Experimental diagenesis of quartz with petroleum; Diagenese experimentale du quartz en presence d'hydrocarbures

Energy Technology Data Exchange (ETDEWEB)

Teinturier, St.

2002-11-01

Quartz cementation has a great impact on petroleum reservoir quality by controlling the porosity and thus the gas or oil storage. However, the possible cementation of quartz during petroleum emplacement is still debated. In most cases, the reconstitution and the understanding of diagenetic processes is based on fluid inclusions studies. However, many questions concerning the representativeness and the reading of the fluid inclusions still remains misunderstood. The experiments were carried out in a silica{+-}water{+-}salts{+-}oil{+-}gas system with the objective to simulate the siliceous diagenesis of natural petroleum reservoirs and to better understand the mechanisms of fluid inclusions formation and quartz cementation in a water and/or petroleum system. Calibration curves have been established using Raman micro-spectroscopy and synthetic reference inclusions to calculate the methane content of aqueous inclusions in the H{sub 2}O-CH{sub 4}-NaCl system. A quantitative procedure for FT-IR micro-spectrometry has been developed to obtain, from individual petroleum fluid inclusions, mole % concentrations of methane, alkanes and carbon dioxide as constraints to thermodynamic modelling. Synthetic aqueous inclusions were created within quartz micro-fractures, with methane (from 150 deg C-200 bar), with petroleum (from 184 deg C-163 bar) and inside quartz overgrowth with the presence of hydrocarbons (from 277 deg C-300 bar). Synthetic petroleum inclusions were created with different water/oil ratios (W/O) within quartz micro-fractures (0quartz overgrowth (10

Conjugation of gold nanoparticles and recombinant human endostatin modulates vascular normalization via interruption of anterior gradient 2-mediated angiogenesis.

Science.gov (United States)

Pan, Fan; Yang, Wende; Li, Wei; Yang, Xiao-Yan; Liu, Shuhao; Li, Xin; Zhao, Xiaoxu; Ding, Hui; Qin, Li; Pan, Yunlong

2017-07-01

Several studies have revealed the potential of normalizing tumor vessels in anti-angiogenic treatment. Recombinant human endostatin is an anti-angiogenic agent which has been applied in clinical tumor treatment. Our previous research indicated that gold nanoparticles could be a nanoparticle carrier for recombinant human endostatin delivery. The recombinant human endostatin-gold nanoparticle conjugates normalized vessels, which improved chemotherapy. However, the mechanism of recombinant human endostatin-gold nanoparticle-induced vascular normalization has not been explored. Anterior gradient 2 has been reported to be over-expressed in many malignant tumors and involved in tumor angiogenesis. To date, the precise efficacy of recombinant human endostatin-gold nanoparticles on anterior gradient 2-mediated angiogenesis or anterior gradient 2-related signaling cohort remained unknown. In this study, we aimed to explore whether recombinant human endostatin-gold nanoparticles could normalize vessels in metastatic colorectal cancer xenografts, and we further elucidated whether recombinant human endostatin-gold nanoparticles could interrupt anterior gradient 2-induced angiogenesis. In vivo, it was indicated that recombinant human endostatin-gold nanoparticles increased pericyte expression while inhibit vascular endothelial growth factor receptor 2 and anterior gradient 2 expression in metastatic colorectal cancer xenografts. In vitro, we uncovered that recombinant human endostatin-gold nanoparticles reduced cell migration and tube formation induced by anterior gradient 2 in human umbilical vein endothelial cells. Treatment with recombinant human endostatin-gold nanoparticles attenuated anterior gradient 2-mediated activation of MMP2, cMyc, VE-cadherin, phosphorylation of p38, and extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) in human umbilical vein endothelial cells. Our findings demonstrated recombinant human endostatin-gold nanoparticles might normalize

Mineralogical anomalies and their influences on elemental geochemistry of the main workable coal beds from the Dafang Coalfield, Guizhou, China

Science.gov (United States)

Dai, S.; Ren, D.; Li, D.; Chou, C.-L.; Luo, K.

2006-01-01

Mineralogy and geochemistry of the No. 11 Coal bed were investigated by using inductively-coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF), scanning electron microscopy equipped with energy-dispersive X-ray (SEM-EDX), sequential chemical extraction procedure (SCEP), and optical microscopy. The results show that the No. 11 Coal bed has very high contents of veined quartz (Vol. 11.4%) and veined ankerite (Vol. 10.2 %). The veined ankerite was generally coated by goethite and the veined quartz embraced chalcopyrite, sphalerite, and selenio-galena. In addition, a trace amount of kaolinite was filled in the veins. These seven minerals often occur in the same veins. The formation temperatures of the veined ankerite and quartz are 85??C and 180??C respectively, indicating their origins of iron-rich calcic and siliceous low-temperature hydrothermal fluids in different epigenetic periods. Studies have also found that the veined quartz probably formed earlier than the veined ankerite, and at least three distinct ankerite formation stages were observed by the ration of Ca/Sr and Fe/Mn of ankerite. The mineral formation from the early to late stage is in order of sulfide, quartz, kaolinite, ankerite, and goethite. The veined ankerite is the dominant source of Mn, Cu, Ni, Pb, and Zn, which are as high as 0.09%, 74.0 ??g/g, 33.6 ??g/g, 185 ??g/g, and 289 ??g/g in this coal seam, respectively. However, the veined quartz is the main carrier of Pd, Pt, and Ir, which are 1.57 ??g/g, 0.15 ??g/g, and 0.007 ??g/g in this coal seam, respectively. In addition, chalcopyrite, sphalerite, and selenio-galena of hydrothermal origin were determined in the veined quartz, and these three sulfide minerals are also important carriers of Cu, Zn and Pb in the No. 11 Coal bed.

Gold and other metals in big sagebrush (Artemisia tridentata Nutt.) as an exploration tool, Gold Run District, Humboldt County, Nevada

Science.gov (United States)

Erdman, J.A.; Cookro, T.M.; O'Leary, R. M.; Harms, T.F.

1988-01-01

Big sagebrush - a cold-desert species that dominates the terrain over large parts of western United States - was sampled along several traverses that crossed thermally metamorphosed limestone, phyllitic shale, and schist of the Middle and Upper Cambrian Preble Formation that host skarn-, disseminated gold and silver-, and hot springs gold-type mineral occurrences. Patterns of detectable levels of gold (8 to 28 ppb or ng g-1) in ash of new growth were consistent with areas affected by known or suspected gold mineralization. Soils collected along one of the traverses where a selenium-indicator plant was common contained no gold above background levels of 2ppb, but were consistently high in As, Sb, and Zn, and several samples were unusually high in Se (maximum 11 ppm or ??g g-1). Sagebrush along this traverse contained Li at levels above norms for this species. We also found a puzzling geochemical anomaly at a site basinward from active hot springs along a range-front fault scarp. Sagebrush at this site contained a trace of gold and an unusually high concentration of Cd (13 ppm) and the soil had anomalous concentrations of Cd and Bi (3.2 and 6 ppm, respectively). The source of this anomaly could be either metal-rich waters from an irrigation ditch or leakage along a buried fault. Despite the limited nature of the study, we conclude that gold in sagebrush could be a cost-effective guide to drilling locations in areas where the geology seems favorable for disseminated and vein precious metals. ?? 1988.

Study of seed for synthetical quartz

International Nuclear Information System (INIS)

Suzuki, C.K.; Torikai, D.

1988-01-01

Natural quartz blocks for seed (synthetic quartz technology) were studied by using various characterization techniques, such as X-ray topography, optical micrography, inspectoscopy, polariscopy and conoscopy, and etching. One of the most commonly found defect is the electrical or Dauphine twin. In The present research, we have developed a methodology to obtain a highly perfect seed for the synthetic quartz industries. (author) [pt

Study of the electrodeposition of rhenium thin films by electrochemical quartz microbalance and X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Schrebler, R.; Cury, P.; Suarez, C.; Munoz, E.; Vera, F.; Cordova, R.; Gomez, H.; Ramos-Barrado, J.R.; Leinen, D.; Dalchiele, E.A.

2005-01-01

Rhenium thin films were prepared by electrodeposition from an aqueous solution containing 0.1 M Na 2 SO 4 +H 2 SO 4 , pH 2 in presence of y mM HReO 4 . As substrates polycrystalline gold (y=0.75 mM HReO 4 ) and monocrystalline n-Si(100) (y=40 mM HReO 4 ) were used. The electrochemical growth of rhenium was studied by cyclic voltammetry and electrochemical quartz microbalance on gold electrodes. The results found in the potential region before the hydrogen evolution reaction (her) showed that ReO 3 , ReO 2 and Re 2 O 3 with different hydration grades can be formed. In the potential region where the her is occurring, either on gold or n-Si(100) the electrodeposition of metallic rhenium takes place. On both substrates, rhenium films were formed by electrolysis at constant potential and X-ray photoelectron spectroscopy technique was used to characterise these deposits. It was concluded that the electrodeposited films were of metallic rhenium and only the uppermost atomic layer contained rhenium oxide species

THE NEOPROTEROZOIC ISLAND-ARC ASSOCIATION OF THE MUKODEK GOLD-ORE FIELD, NORTHERN BAIKAL AREA

Directory of Open Access Journals (Sweden)

V. A. Vanin

2014-01-01

Full Text Available Metamorphosed volcanic rocks of the Ushmukan suite were studied in the Mukodek gold-ore field located in the Baikal-Muya belt in the Northern Baikal area, Russia. The Ushmukan suite shows interleaving of ortoschists which compositions are widely variable. Basalt-andesite-dacite series of normal alkalinity are the substrate of the studied metavolcanic rocks. Based on the set of geochemical characteristics, it is concluded that the rocks were formed in suprasubduction geodynamic conditions corresponding to a mature island arc. The proximity of the geological locations and the similarity of the geochemical characteristics of the volcanic rocks of the Ushmukan suite and rocks of the Kelyan suite (Neoproterozoic, 823 Ma, which have similar compositions, give grounds to consider these two rock suites as age peers. Specific features of gold distribution through the Mukodek gold-ore field are analyzed. Industrial gold contents are recorded only in berezite-listvenite metasomatic rocks of the gold-quartz-sulfide formation which were formed on metavolcanic rocks of the Ushmukan suite. It is concluded that the volcanic rocks, which are specific of the island-arc setting, could be a source of gold for deposits in the Mukodek gold-ore field. 

Geochemistry and mineralogy of the radioactive minerals associated with some pegmatite veins of the Ukma-Nawahatu-Hursi sector, Purulia Dist., W.B., in the precambrian Chhotanagpur gneissic complex

International Nuclear Information System (INIS)

Baidya, Tapan Kumar

2013-01-01

Some barite-bearing pegmatites in the Ukma-Nawahatu-Hursi sector (23° 25'-26'N, 86° 02'-04'E) of the Purulia dist., West Bengal, have association of radioactive minerals in the form of coarse grained pitchblack lumps and irregular patches. This radioactive belt of about 15 km length running through Ukma, Nawahatu and Hursi areas follows ENE-WSW trending shear zone. The barite-bearing pegmatites occur as lenses or lenticular veins hosted by garnetiferous sillimanite-biotite-quartz-schist or occasionally by migmatite. Near Nawahatu the radioactive barite-pegmatite vein occurs at or near the junction between footwall amphibolite and hangingwall garnetiferous schist. The pegmatite veins have mainly followed the schistosity of the host rock and dip 70°-80° towards south

What Are Varicose Veins?

Science.gov (United States)

... Leer en español What Is Varicose (VAR-i-kos) veins are swollen, twisted veins that you can ... TA-ze-uhs), spider veins, varicoceles (VAR-i-ko-seals), and other vein problems. Telangiectasias Telangiectasias are ...

Adrenal Vein Sampling for Conn’s Syndrome: Diagnosis and Clinical Outcomes

Directory of Open Access Journals (Sweden)

Amy R. Deipolyi

2015-06-01

Full Text Available Adrenal vein sampling (AVS is the gold standard test to determine unilateral causes of primary aldosteronism (PA. We have retrospectively characterized our experience with AVS including concordance of AVS results and imaging, and describe the approach for the PA patient in whom bilateral AVS is unsuccessful. We reviewed the medical records of 85 patients with PA and compared patients who were treated medically and surgically on pre-procedure presentation and post-treatment outcomes, and evaluated how technically unsuccessful AVS results were used in further patient management. Out of the 92 AVS performed in 85 patients, AVS was technically successful bilaterally in 58 (63% of cases. Either unsuccessful AVS prompted a repeat AVS, or results from the contralateral side and from CT imaging were used to guide further therapy. Patients who were managed surgically with adrenalectomy had higher initial blood pressure and lower potassium levels compared with patients who were managed medically. Adrenalectomy results in significantly decreased blood pressure and normalization of potassium levels. AVS can identify surgically curable causes of PA, but can be technically challenging. When one adrenal vein fails to be cannulated, results from the contralateral vein can be useful in conjunction with imaging and clinical findings to suggest further management.

Evaluation on corrosively dissolved gold induced by alkanethiol monolayer with atomic absorption spectroscopy

International Nuclear Information System (INIS)

Cao Zhong; Zhang Ling; Guo Chaoyan; Gong Fuchun; Long Shu; Tan Shuzhen; Xia Changbin; Xu Fen; Sun Lixian

2009-01-01

We have monitored a gold corrosive dissolution behavior accompanied in n-alkanethiol like n-dodecanethiol assembled process with in situ quartz crystal microbalance (QCM), and then observed it with atomic force microscopy (AFM) which showed an evident image of corrosive defects or holes produced on gold substrate, corresponding to gold dissolution induced by the alkanethiol molecules in the presence of oxygen. For detection of the dissolved gold defects during alkanethiol assembled process, an atomic absorption spectroscopy (AAS) has been carried out in this paper, and the detection limit for the dissolved gold could be evaluated to be 15.4 ng/mL. The amount of dissolved gold from the substrates of gold plates as functions of immersion time, acid media, solvents and thiol concentration has been examined in the oxygen saturated solutions. In comparison with in situ QCM method, the kinetics behavior of the long-term gold corrosion on the gold plates in 1.0 mmol/L of n-dodecanethiol solution determined with AAS method was a slow process, and its corrosion rate on gold dissolution could be evaluated to be about 4.4 x 10 -5 ng.cm -2 .s -1 , corresponding to 1.3 x 10 8 Au atoms.cm -2 .s -1 , that was much smaller than that of initial rate monitored with in situ QCM. Both kinetics equations obtained with QCM and AAS showed a consistent corrosion behavior on gold surfaces.

Varicose vein - noninvasive treatment

Science.gov (United States)

... spider veins. These are small varicose veins. Salt water (saline) or a chemical solution is injected into the varicose vein. The vein will harden and then disappear. Laser treatment can be used on the surface of the skin. Small bursts ...

Trace element mapping of pyrite from Archean gold deposits – A comparison between PIXE and EPMA

Energy Technology Data Exchange (ETDEWEB)

Agangi, A., E-mail: aagangi@uj.ac.za [University of Johannesburg, Department of Geology, Auckland Park 2006 (South Africa); Przybyłowicz, W., E-mail: przybylowicz@tlabs.ac.za [Materials Research Department, iThemba LABS, National Research Foundation, Somerset West 7129 (South Africa); AGH University of Science and Technology, Faculty of Physics & Applied Computer Science, Al. A. Mickiewicza 30, 30-059 Krakow (Poland); Hofmann, A., E-mail: ahofmann@uj.ac.za [University of Johannesburg, Department of Geology, Auckland Park 2006 (South Africa)

2015-04-01

Chemical zoning of pyrites can record the evolution of mineralising fluids at widely varying P–T conditions ranging from diagenesis to medium-grade metamorphism. If preserved, zoning can reveal growth textures, brecciation and veining, resorption and recrystallisation events, thus shedding light on the processes that contributed to ore formation. Chemical zoning of sulfides is invisible in optical microscopy, but can be studied by chemical etching, high-contrast back-scattering electron images, and elemental imaging. In this study we compared micro-PIXE and WDS-EPMA elemental maps on the chemically zoned pyrites in mineralised vein-bearing samples from the Sheba and Fairview gold mines in the Barberton Greenstone Belt, South Africa. Elemental images show complex distribution of trace elements, suggesting multiple events of pyrite crystallisation and gold deposition. EPMA maps show fine-scale variations reflecting growth and recrystallisation textures marked, in particular, by variations of As, Ni, and Co. In PIXE maps, gold occurs both as finely-distributed and discrete inclusions, suggesting incorporation in the pyrite structure as solid solution, and deposition as electrum inclusions, respectively. Micro-PIXE and EPMA provide complementary information, forming together a powerful tool to obtain information on chemical zoning of pyrites in ore deposits.

Quartz gauge response in ion radiation

International Nuclear Information System (INIS)

Taylor, P.E.; Gilbert, P.H.; Kernthaler, C.; Anderson, M.U.

1995-01-01

This paper describes recent work to make high quality quartz gauge (temporal and spatial) shock wave measurements in a pulsed ion beam environment. Intense ion beam radiation, nominally 1 MeV protons, was deposited into material samples instrumented with shunted quartz gauges adjacent to the ion deposition zone. Fluence levels were chosen to excite three fundamentally different material response modes (1) strong vapor, (2) combined vapor and melt phase and (3) thermoelastic material response. A unique quartz gauge design was utilized that employed printed circuit board (PCB) technology to facilitate electrical shielding, ruggedness, and fabrication at sign e meeting the essential one dimensional requirements of the characterized Sandia shunted quartz gauge. Shock loading and unloading experiments were conducted to evaluate the piezoelectric response of the coupled quartz gauge/PCB transducer. High fidelity shock wave profiles were recorded at the three ion fluence levels providing dynamic material response data for vapor, melt and solid material phases

Ligation of superior mesenteric vein and portal to splenic vein anastomosis after superior mesenteric-portal vein confluence resection during pancreaticoduodenectomy - Case report.

Science.gov (United States)

Tang, Jianlin; Abbas, Jihad; Hoetzl, Katherine; Allison, David; Osman, Mahamed; Williams, Mallory; Zelenock, Gerald B

2014-12-01

62 year old Caucasian female with pancreatic head mass abutting the superior mesenteric vein (SMV) presented with fine needle aspiration biopsy confirmed diagnosis of ductal adenocarcinoma. CT scan showed near complete obstruction of portal vein and large SMV collateral development. After 3 months of neoadjuvant therapy, her portal vein flow improved significantly, SMV collateral circulation was diminished. Pancreaticoduodenectomy (PD) and superior mesenteric portal vein (SMPV) confluence resection were performed; A saphenous vein interposition graft thrombosed immediately. The splenic vein remnant was distended and adjacent to the stump of the portal vein. Harvesting an internal jugular vein graft required extra time and using a synthetic graft posed a risk of graft thrombosis or infection. As a result, we chose to perform a direct anastomosis of the portal and splenic vein in a desperate situation. The anastomosis decompressed the mesenteric venous system, so we then ligated the SMV. The patient had an uneventful postoperative course, except transient ascites. She redeveloped ascites more than one year later. At that time a PET scan showed bilateral lung and right femur metastatic disease. She expired 15 months after PD. The lessons we learned are (1) Before SMPV confluence resection, internal jugular vein graft should be ready for reconstruction. (2) Synthetic graft is an alternative for internal jugular vein graft. (3) Direct portal vein to SMV anastomosis can be achieved by mobilizing liver. (4) It is possible that venous collaterals secondary to SMV tumor obstruction may have allowed this patient's post-operative survival.

Bald Mountain gold mining district, Nevada: A Jurassic reduced intrusion-related gold system

Science.gov (United States)

Nutt, C.J.; Hofstra, A.H.

2007-01-01

The Bald Mountain mining district has produced about 2 million ounces (Moz) of An. Geologic mapping, field relationships, geochemical data, petrographic observations, fluid inclusion characteristics, and Pb, S, O, and H isotope data indicate that An mineralization was associated with a reduced Jurassic intrusion. Gold deposits are localized within and surrounding a Jurassic (159 Ma) quartz monzonite porphyry pluton and dike complex that intrudes Cambrian to Mississippian carbonate and clastic rocks. The pluton, associated dikes, and An mineralization were controlled by a crustal-scale northwest-trending structure named the Bida trend. Gold deposits are localized by fracture networks in the pluton and the contact metamorphic aureole, dike margins, high-angle faults, and certain strata or shale-limestone contacts in sedimentary rocks. Gold mineralization was accompanied by silicification and phyllic alteration, ??argillic alteration at shallow levels. Although An is typically present throughout, the system exhibits a classic concentric geochemical zonation pattern with Mo, W, Bi, and Cu near the center, Ag, Pb, and Zn at intermediate distances, and As and Sb peripheral to the intrusion. Near the center of the system, micron-sized native An occurs with base metal sulfides and sulfosalts. In peripheral deposits and in later stages of mineralization, Au is typically submicron in size and resides in pyrite or arsenopyrite. Electron microprobe and laser ablation ICP-MS analyses show that arsenopyrite, pyrite, and Bi sulfide minerals contain 10s to 1,000s of ppm Au. Ore-forming fluids were aqueous and carbonic at deep levels and episodically hypersaline at shallow levels due to boiling. The isotopic compositions of H and O in quartz and sericite and S and Pb in sulfides are indicative of magmatic ore fluids with sedimentary sulfur. Together, the evidence suggests that Au was introduced by reduced S-bearing magmatic fluids derived from a reduced intrusion. The reduced

Carbonate hosted gold deposit in Tasmania, Australia

International Nuclear Information System (INIS)

Abadi, M.H.

1999-01-01

Full text: This study uses elemental and isotopic composition of carbonates associated with gold from Henty and Beaconsfield in Tasmania, Australia, to illustrate source of gold-bearing fluids, salinity, temperature and dissolution and reprecipitation of carbonate. The Beaconsfield and Henty gold mines are located in northern and western Tasmania respectively. Gold mineralisation in Beaconsfield occurs within the quartz-carbonate Tasmania Reef (Lower to Middle Palaeozoic sequence, Hills, 1998). The Henty gold mine is located at the base of the Cambrian Tyndall Group (volcano-sedimentary succession, White and McPhie, 1996) close to Henty Fault. Gold in carbonate samples from Henty ranges from 7.7 to 9360 ppm and in Beaconsfield ranges from 0.01 to 434 ppm. The amount of carbonate in samples from Henty and Beaconsfield gold mines varies from approximately 24 to 99.8%. Bivariate plot of Ca relative to total amounts of Mg, Fe and Mn illustrates that the major carbonate minerals at Beaconsfield and Henty gold mines are magnesian ankerite and calcite. The difference in carbonate mineralogy, at Henty and Beaconsfield gold mines, is attributed to the composition of fluids responsible for carbonate alteration. Gold and magnesium in Beaconsfield ankerite are derived from the leaching of Cambrian ultramafic rocks during the Devonian by the passage of meteoric fluids through tectonically affected Ordovician carbonates (Rao and Adabi, 1999). The total concentration of Fe and Mn are low (0.5 to 2%) in Henty and high (1 to 17.5%) in Beaconsfield ankerite, possibly due to oxidising conditions at Henty and reducing conditions at Beaconsfield gold mines during gold mineralisation. Variation of Sr values between Beaconsfield ankerite and Henty calcite is related to dissolution of limestone that increase Sr concentrations in gold mineralising fluids. Na values in both Beaconsfield (20 to 1100 ppm) and Henty carbonates (25 to 1650 ppm) suggest low salinity fluids responsible for gold

Fault rocks and veins formation in the crystalline Palaeozoic basement of the N margin of the Littoral Chain (Catalan Coastal Ranges, NE Spain)

Science.gov (United States)

Alías, Gemma; Belmonte, Alba; Cantarero, Irene; Inglés, Montserrat; Travé, Anna

2013-04-01

The Littoral Chain corresponds to a horst of NE-SW direction formed during the Neogene extension which in the studied area (Collserola-Montnegre massif) is mainly composed by Paleozoic materials. At the northern margin the horst limits with the Vallès basin which is infilled by Miocene detrital materials. In the Forques Hill, two km to the est of Martorell, an excellent outcrop of Ordovician phyllites summarise an spread tectonic evolution from Hercynian to Neogene deformation. This work evaluates the behaviour of phyllites during the Hercynian ductile deformation and later during the fragile Mesozoic and Neogene tectonics. The weakness of these rocks together with the situation very close to the Vallès Fault favour that this area concentrates many deformation structures related to extensional tectonics, such as veins, cataclasites and gouges. Phyllites present a pervasive regional hercynian foliation oriented WNW-ESE and dipping moderately to the NNE; a huge amount of quartz veins, up to 20% of the rock volume, were injected during and immediately after the main foliation development. Two groups of fractures cutting the phyllites can be distinguished in the field according to the fault rock products, the vein infilling, the orientation and the geometry. The first one corresponds to Mesozoic fractures that have a NE-SW trend and dip indistinctly to the NW or SE, in a conjugate system. They are characterized by the formation of a broad zone of 0,2 m up to 1,5 m formed either by cataclasites or en echelon veins that indicate a normal movement. The cataclasites are cohesive greenish rocks, with 50% of clasts of wall rock from mm to dm in size. Neoformed minerals in the matrix are chlorite - albite - barite ± titanite and rutile. Veins are white to pinkish in colour and two types of infill have been identified: albite - chlorite - iron oxides± rutile and dolomite - chlorite. The second group belongs to Neogene fractures which although similar orientation than those

Accessory hepatic vein: MR imaging

International Nuclear Information System (INIS)

Lee, Chang Hee; Rho, Tack Soo; Cha, Sang Hoon; Park, Cheol Min; Cha, In Ho

1995-01-01

To evaluate the MR appearance of the accessory hepatic veins. The study included 87 consecutive patients for whom abdominal MR images were obtained. The subjects who had liver lesion or hepatic vascular abnormalities were excluded. Couinaud classified accessory hepatic veins into inferior and middle right hepatic veins. Our major interests were evaluation of the incidence, morphology, and location of the accessory hepatic vein. Inferior right hepatic vein was demonstrated in 43 out of 87 patients (49%). The morphology was linear in 35 patients (80.5%), and V-shaped in 8 patients (19.5%). In 40 patients (93%), the inferior right hepatic vein was located in the posteroinferior aspect of the right lobe. Middle right hepatic vein was demonstrated in 7 out of 87 patients (8%). All were single linear in morphology, combined with the inferior right hepatic vein, and located between the right hepatic vein and inferior right hepatic vein. The accessory hepatic vein was demonstrated in 49% among the Korean adult population, and was located in posteroinferior portion of the liver, in 93%

Specific interactions of functionalised gold surfaces with ammonium perchlorate or starch; towards a chemical cartography of their mixture

Energy Technology Data Exchange (ETDEWEB)

Mercier, D. [CNRS, UMR CNRS 7609, Laboratoire de Reactivite de Surface, Paris (France); Universite Pierre et Marie Curie - UPMC Paris VI, Laboratoire de Reactivite de Surface, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratoire de recherche conventionne CEA/UPMC n Degree-Sign 1, Paris (France); Mercader, C.; Quere, S.; Hairault, L. [CEA, DAM, Le Ripault, F-37260 Monts (France); Laboratoire de recherche conventionne CEA/UPMC n Degree-Sign 1, Paris (France); Methivier, C. [CNRS, UMR CNRS 7609, Laboratoire de Reactivite de Surface, Paris (France); Universite Pierre et Marie Curie - UPMC Paris VI, Laboratoire de Reactivite de Surface, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratoire de recherche conventionne CEA/UPMC n Degree-Sign 1, Paris (France); Pradier, C.M., E-mail: claire-Marie.pradier@upmc.fr [CNRS, UMR CNRS 7609, Laboratoire de Reactivite de Surface, Paris (France); Universite Pierre et Marie Curie - UPMC Paris VI, Laboratoire de Reactivite de Surface, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratoire de recherche conventionne CEA/UPMC n Degree-Sign 1, Paris (France)

2012-10-01

Highlights: Black-Right-Pointing-Pointer Measurements of interactions by Quartz Crystal Microbalance. Black-Right-Pointing-Pointer AFM and CFM measurements, tip functionalisation. Black-Right-Pointing-Pointer Surface nano-imaging. - Abstract: By functionalising gold samples, planar wafers or AFM tips, with an acid- or an amino acid-terminated thiols, mercaptoundecanoic acid (MUA) and homocystein (H-Cyst) respectively, we were able to differentiate the interactions with ammonium perchlorate (AP) and starch (S), two components of a nanocomposition mixture. To do so, the interaction between gold functionalized surfaces and the two targeted compounds have been characterized and quantified by several complementary techniques. Polarisation modulation-infrared spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS), providing chemical analyses of gold surfaces after contacting S or AP, proved that both compounds were retained on MUA or H-Cyst-modified surfaces, but to various extents. Quartz crystal microbalance on-line measurements enabled to monitor the kinetics of interaction and showed distinct differences in the behaviour of MUA and H-Cyst-surfaces towards the two compounds. Having observed that only H-Cyst-modified surfaces enables to get a contrast on the chemical force microscopy (CFM) images, this new result could be well explained by examining the data obtained by combining the above-mentioned surface characterisation techniques.

Positron states and nanoobjects in proton-irradiated quartz single crystals: Positronium atom in quartz

International Nuclear Information System (INIS)

Grafutin, V. I.; Zaluzhnyi, A. G.; Timoshenkov, S. P.; Britkov, O. M.; Ilyukhina, O. V.; Myasishcheva, G. G.; Prokop'ev, E. P.; Funtikov, Yu. V.

2008-01-01

The influence of proton bombardment and metal atom impurities on the structure of quartz single crystals has been studied. The related defects have been studied using positron annihilation spectroscopy (angular correlation of positron-annihilation photons), acoustic absorption, and optical absorption measurements. It is shown that the presence of a narrow component f in the angular distribution of annihilation photons (ADAP), which is related to the formation of parapositronium, determines a high sensitivity of this method with respect to features of the crystal structure of quartz. It is established that the defectness of the structure of irradiated quartz crystals can be characterized by the ratio f/f 0 of the relative intensities of narrow components in the ADAP curves measured before (f 0 ) and after (f) irradiation. Any process leading to a decrease in the probability of positronium formation (e.g., positron loss as a result of the trapping on defects and the interaction with impurity atoms and lattice distortions) decreases the intensity of the narrow component. Based on the ADAP data, estimates of the radii and concentrations of nanodefects in quartz have been obtained and their variation upon annealing at temperatures up to T = 873 K has been studied

Ligation of superior mesenteric vein and portal to splenic vein anastomosis after superior mesenteric-portal vein confluence resection during pancreaticoduodenectomy – Case report

Science.gov (United States)

Tang, Jianlin; Abbas, Jihad; Hoetzl, Katherine; Allison, David; Osman, Mahamed; Williams, Mallory; Zelenock, Gerald B.

2014-01-01

62 year old Caucasian female with pancreatic head mass abutting the superior mesenteric vein (SMV) presented with fine needle aspiration biopsy confirmed diagnosis of ductal adenocarcinoma. CT scan showed near complete obstruction of portal vein and large SMV collateral development. After 3 months of neoadjuvant therapy, her portal vein flow improved significantly, SMV collateral circulation was diminished. Pancreaticoduodenectomy (PD) and superior mesenteric portal vein (SMPV) confluence resection were performed; A saphenous vein interposition graft thrombosed immediately. The splenic vein remnant was distended and adjacent to the stump of the portal vein. Harvesting an internal jugular vein graft required extra time and using a synthetic graft posed a risk of graft thrombosis or infection. As a result, we chose to perform a direct anastomosis of the portal and splenic vein in a desperate situation. The anastomosis decompressed the mesenteric venous system, so we then ligated the SMV. The patient had an uneventful postoperative course, except transient ascites. She redeveloped ascites more than one year later. At that time a PET scan showed bilateral lung and right femur metastatic disease. She expired 15 months after PD. Conclusion The lessons we learned are (1) Before SMPV confluence resection, internal jugular vein graft should be ready for reconstruction. (2) Synthetic graft is an alternative for internal jugular vein graft. (3) Direct portal vein to SMV anastomosis can be achieved by mobilizing liver. (4) It is possible that venous collaterals secondary to SMV tumor obstruction may have allowed this patient's post-operative survival. PMID:25568802

Fluid inclusion and noble gas studies of the Dongping gold deposit, Hebei Province, China: A mantle connection for mineralization?

Science.gov (United States)

Mao, J.; Li, Y.; Goldfarb, R.; He, Y.; Zaw, K.

2003-01-01

The Dongping gold deposit (>100 t Au) occurs about 200 km inboard of the northern margin of the North China craton. The deposit is mainly hosted by syenite of a middle Paleozoic alkalic intrusive complex that was emplaced into Late Archean basement rocks. Both groups of rocks are intruded by Late Jurassic to Early Cretaceous crustal-melt granite dikes and stocks, some within a few kilometers of the deposit. The gold ores were deposited during this latter magmatic period at about 150 Ma, a time that was characterized by widespread regional north-south compression that formed the east-west-trending Yanshan deformational belt. The ores include both the telluride mineral-bearing, low sulfide quartz veins and the highly K-feldspar-altered syenite, with most of the resource concentrated in two orebodies (1 and 70). Fluid inclusion microthermometry indicates heterogeneous trapping of low-salinity (e.g., 5-7 wt % NaCl equiv) fluids that varied from a few to 60 mole percent nonaqueous volatile species. Laser Raman spectroscopy confirms that the vapor phase in these inclusions is dominated by CO2, but may be comprised of as much as 9 mole percent H2S and 20 mole percent N2; methane concentrations in the vapor phase are consistently interaction of ore fluids with surrounding crustal rocks, which may have contributed additional He to the fluids. A mantle source for at least some of the components of the gold-forming fluid is consistent with upwelling of hot asthenosphere and erosion of as much as 100 to 150 km of cool Archean lithosphere beneath the craton during this time. The Dongping deposit is located along the 100-km-wide north-south gravity lineament, which marks the western border of the thinned crust. As both regional metamorphism of Mesoproterozoic and younger cover rocks, and widespread granite magmatism, also occurred at ca. 150 Ma, it is unclear as to whether one or both of these also contributed fluid and/or metals to the hydrothermal system. Importantly, these

Quartz crystal reinforced quartz glass by spark plasma sintering

International Nuclear Information System (INIS)

Torikai, D.; Barazani, B.; Ono, E.; Santos, M.F.M.; Suzuki, C.K.

2011-01-01

The Spark Plasma Sintering presents fast processing time when compared to conventional sintering techniques. This allows to control the grain growth during sintering as well as the diffusion rate of a multi-material compounds, and make possible obtainment of functionally graded materials and nanostructured compounds. Powders of high purity silica glass and crystalline silica were sintered in a SPS equipment at temperatures around 1350° C, i.e., above the softening temperature of silica glass and below the melting temperature of quartz crystal. As a result, glass ceramics with pure silica glass matrix reinforced with crystalline alpha-quartz grains were fabricated at almost any desired range of composition, as well as controlled size of the crystalline reinforcement. X-ray diffraction and density measurements showed the possibility to manufacture a well controlled density and crystallinity glass-ceramic materials. (author)

The stibian mustard gold from the Kriván¿ Au deposit,Tatry Mts., Slovak Republic

DEFF Research Database (Denmark)

Makovicky, Emil; Martin, Chovan; František, Bakos

2007-01-01

The Kriván Au-Sb mineralization is hosted in several subhorizontal variscan mylonite zones located in granitoid rocks. Ore minerals occur in thin lens-shaped quartz veinlets. Albite, chlorite, calcite, muscovite and tourmaline are minor gangue minerals. Four mineral assemblages have been recognized...... - (1) pyrite-arsenopyrite-gold, (2) stibnite-sulfosalts-sphalerite, (3) tetrahedrite- chalcopyrite-electrum, (4) supergene minerals. Isometric and irregular grains of mustard gold are 0.X mm in size. In refl ected light it is isotropic with low refl ectivity and orange-red or brown-yellow color...... with pores more or less fi lled by oxidation products of Sb and Fe. Compositionally it does not conform with stibian mustard gold from Yakutia and Bolivia, approximately AuSb1.4O2.1, derived from decomposition of aurostibite, but it conforms with mustard gold from Krásná Hora, Czech Republic. For this type...

Additive manufacturing of transparent fused quartz

Science.gov (United States)

Luo, Junjie; Hostetler, John M.; Gilbert, Luke; Goldstein, Jonathan T.; Urbas, Augustine M.; Bristow, Douglas A.; Landers, Robert G.; Kinzel, Edward C.

2018-04-01

This paper investigates a filament-fed process for additive manufacturing (AM) of fused quartz. Glasses such as fused quartz have significant scientific and engineering applications, which include optics, communications, electronics, and hermetic seals. AM has several attractive benefits such as increased design freedom, faster prototyping, and lower processing costs for small production volumes. However, current research into glass AM has focused primarily on nonoptical applications. Fused quartz is studied here because of its desirability for use in high-quality optics due to its high transmissivity and thermal stability. Fused quartz filaments are fed into a CO2 laser-generated molten region, smoothly depositing material onto the workpiece. Spectroscopy and pyrometry are used to measure the thermal radiation incandescently emitted from the molten region. The effects of the laser power and scan speed are determined by measuring the morphology of single tracks. Thin walls are printed to study the effects of layer-to-layer height. This information is used to deposit solid pieces including a cylindrical-convex shape capable of focusing visible light. The transmittance and index homogeneity of the printed fused quartz are measured. These results show that the filament-fed process has the potential to print transmissive optics.

Varicose Veins - Multiple Languages

Science.gov (United States)

... Concerns and Discomforts of Pregnancy: Varicose Veins - English MP3 Concerns and Discomforts of Pregnancy: Varicose Veins - 简体中文 (Chinese, Simplified (Mandarin dialect)) MP3 Concerns and Discomforts of Pregnancy: Varicose Veins - English ...

Metallogeny of the Gold Quadrilateral: style and characteristics of epithermal - subvolcanic mineralized structures, South Apuseni Mts., Romania

Directory of Open Access Journals (Sweden)

S̡erban-Nicolae Vlad

2004-04-01

Full Text Available The Romanian territory contains numerous ore deposits mined since pre-Roman times. An assessment of historical gold production of the Gold Quadri-lateral (GQ yielded a total estimate of 55.7 Moz of gold throughout an area of 2400 km2. Interpreted in terms of mineralization density this is 23,208 oz of gold/ km2. The geological setting of the GQ is represented mainly by Tertiary (14.7 My to 7.4 My calc-alkaline volcano-plutonic complexes of intermediate character in sedimentary basins of molasse type. These basins are tectonically controlled by NW-SE lineation across early Alpine magmatic products, i.e. subduction related Jurassic-Lower Cretaceous igneous association (island arc ophiolites and granitoids and Upper Cretaceous igneous association (banatites. The Tertiary magmatism is associated with extensional tectonics caused by NE escape of the Pannonian region during Upper Oligocene-Lower Miocene times. As a result of tectono-magmatic and mineralization-alteration characteristics, two metallogenetical types were separated in the GQ, i.e. calc-alkaline andesitic (CAM and sub-alkaline rhyodacitic (SRM. Both develop almost entirely low-sulfidation type of Au epithermal mineralization. However, two subtypes, -rich in sulfide (2-7% and -poor in sulfide (7-20% were delineated and correlated with CAM type and SRM type respectively. Furthermore, CAM is connected at deeper levels with Cu-Au+/-Mo porphyry systems in contrast with SRM, which is a non-porphyry environment. The Brad-Săcărâmb district contains mainly CAM type andesitic structures. It is a porphyry environment with epithermal low-sulfidation-rich sulfide vein halo (Barza, Troiţa-Bolcana deposits. However, a few SRM type patterns, such as Măgura Ţebii, Băiţa-Crăciuneşti and Săcărâmb, deposits exhibit Au-Ag-Te low-sulfidation-poor sulfide epithermal vein halo. The Zlatna-Stănija district exhibits similar characteristics, with Au-Ag+/-Pb, Zn veins in Cu-Au subvolcanic

Valsalva and gravitational variability of the internal jugular vein and common femoral vein: Ultrasound assessment

Energy Technology Data Exchange (ETDEWEB)

Beddy, P. [Department of Radiology, The Adelaide and Meath Hospital, Tallaght, Dublin 24 (Ireland)]. E-mail: pbeddy@eircom.net; Geoghegan, T. [Department of Radiology, The Adelaide and Meath Hospital, Tallaght, Dublin 24 (Ireland); Ramesh, N. [Department of Radiology, The Adelaide and Meath Hospital, Tallaght, Dublin 24 (Ireland); Buckley, O. [Department of Radiology, The Adelaide and Meath Hospital, Tallaght, Dublin 24 (Ireland); O' Brien, J. [Department of Radiology, The Adelaide and Meath Hospital, Tallaght, Dublin 24 (Ireland); Colville, J. [Department of Radiology, The Adelaide and Meath Hospital, Tallaght, Dublin 24 (Ireland); Torreggiani, W.C. [Department of Radiology, The Adelaide and Meath Hospital, Tallaght, Dublin 24 (Ireland)

2006-05-15

Purpose: Central venous cannulation via the common femoral vein is an important starting point for many interventions. The purpose of this study was to determine the optimum conditions for cannulation of the femoral vein and to compare these with the relative changes in the internal jugular vein. Methods: High-resolution 2D ultrasound was utilised to determine variability of the calibre of the femoral and internal jugular veins in 10 healthy subjects. Venous diameter was assessed during the Valsalva manoeuvre and in different degrees of the Trendelenburg position. Results: The Valsalva manoeuvre significantly increased the size of the femoral and internal jugular veins. There was a relatively greater increase in femoral vein diameter when compared with the internal jugular vein of 40 and 29%, respectively. Changes in body inclination (Trendelenburg position) did not significantly alter the luminal diameter of the femoral vein. However, it significantly increased internal jugular vein diameter. Conclusions: Femoral vein cannulation is augmented by the Valsalva manoeuvre but not significantly altered by the gravitational position of the subject.

Textural and Isotopic Evidence for Silica Cementation in 1.88 GA Granular Iron Formation

Science.gov (United States)

Brengman, L. A.; Fedo, C.; Martin, W.

2016-12-01

Controls on quartz precipitation mechanisms and silicon isotope fractionation during diagenesis of Precambrian iron formation (IF) are not well constrained. The goal of this study is to identify textural evidence for the relative timing of silica cementation of granular units from the near un-metamorphosed 1.88 Ga Biwabik IF and determine the silicon isotope composition for such a silicification event. The lowermost IF (lower cherty, LC) consists of granular units associated with high-energy sedimentary structures interpreted to represent shallow-marine shelf deposition. Up-section is marked by an abrupt shift to banded units interpreted as a transition to quiescent (deeper) water, followed by a return to granular textures and shallower conditions (upper cherty, UC). We first surveyed granular samples of the lower stromatolitic (LC) and upper oncolitic facies (UC) to identify sedimentary textures and cement. LC units consist of microquartz (chert), megaquartz, hematite, carbonate, and detrital quartz, chert, and quartz/Fe-oxide intraclastic material. In UC samples, space between granular material (hematite, magnetite, quartz ooids/intraclasts) is filled by mega-quartz cement, and cross-cutting mega-quartz veins. We targeted mega-quartz cement, and veins for δ30Si analysis via secondary ion mass spectrometry. The average measured δ30Si value of cement (δ30Siavg. cement UC6b = -3.11 ± 0.21 ‰) is significantly different than associated veins (δ30Siavg. vein UC6b = 0.21 ± 0.21 ‰; δ30Siavg. vein LC4 = 0.39 ± 0.21 ‰), both within and between samples. We interpret the relative difference between cement and veins to represent quartz precipitation under different geochemical conditions, and therefore at different times. Combining isotopic and textural evidence, we interpret silica cementation to pre-date veins, and represent quartz precipitation that either varied in rate, or occurred under closed-system conditions affected by Rayleigh distillation. Both

Quartz-Enhanced Photoacoustic Spectroscopy: A Review

Science.gov (United States)

Patimisco, Pietro; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

2014-01-01

A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis. PMID:24686729

Quartz-Enhanced Photoacoustic Spectroscopy: A Review

Directory of Open Access Journals (Sweden)

Pietro Patimisco

2014-03-01

Full Text Available A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis.

High Momentum Particle Identification Detector The Study of Cesium Iodide Quantum Efficiency Dependency on Substrate Material, Temperature and Quartz Window

CERN Document Server

Wisna, Gde Bimananda M

2014-01-01

The Cesium Iodide (CsI) is used as a material for detecting Cherenkov radiation produced by high momentum particle in High Momentum Particle Identification Detector (HMPID) at ALICE Experiment at CERN. This work provides investigation and analysis of The Quantum Efficiency (QE) result of CsI which is deposited on five samples substrates such as copper passivated red, copper passivated yellow, aluminium, copper coated with nickel and copper coated with nickel then coated with gold. The measurement of five samples is held under temperature $60^{0}$ C and $25^{0}$ C (room temperature) and also with optical quartz window which can be adjusted to limit the wavelength range which reach the CsI. The result shows there are dependency of substrate, temperature due to enhancement effect and also quartz windows usage on QE of CsI. The results of five samples is then compared and analyzed.

Aberrant thermoluminescence dates obtained from primary volcanic quartz

International Nuclear Information System (INIS)

Guerin, Gilles; Samper, Agnes

2007-01-01

This study deals with the dating by thermoluminescence (TL) of quartz from six volcanic formations of the Saint Lucia Island (Lesser Antilles Arc). Quartz microcrystals up to one millimetre in size were extracted from dacites and pumice flows and prepared in a way similar to the well-known inclusion technique. The TL properties of these quartz were used to estimate apparent palaeodoses using the multi-aliquot protocol. The quartz TL was studied in three different spectral domains: red, green and ultraviolet/blue. The calculated annual dose-rates yielded a set of 18 age-estimates. For some samples complementary dates were obtained using high temperature TL (HTTL) of plagioclase feldspars. These latter dates combined with previously determined radiocarbon and unspiked K-Ar dates were used to explore the validity of ages computed from the TL of quartz. Individual values for quartz appear to be scattered and do not match ages deduced from 14 C, unspiked K-Ar or HTTL on plagioclase dates. These results indicate that when conventional TL methodologies derived from the inclusion method are applied to volcanic quartz major dating problems are to be expected

Aberrant thermoluminescence dates obtained from primary volcanic quartz

Energy Technology Data Exchange (ETDEWEB)

Guerin, Gilles [Laboratoire des Sciences du Climat et de l' Environnement, CEA-CNRS, avenue de la Terrasse, 91191 Gif-sur-Yvette (France)], E-mail: gilles.guerin@u-psud.fr; Samper, Agnes [Laboratoire de geochronologie multitechnique (UPS-IPGP), Universite de Paris-Sud Orsay, 91405 Orsay Cedex (France)

2007-10-15

This study deals with the dating by thermoluminescence (TL) of quartz from six volcanic formations of the Saint Lucia Island (Lesser Antilles Arc). Quartz microcrystals up to one millimetre in size were extracted from dacites and pumice flows and prepared in a way similar to the well-known inclusion technique. The TL properties of these quartz were used to estimate apparent palaeodoses using the multi-aliquot protocol. The quartz TL was studied in three different spectral domains: red, green and ultraviolet/blue. The calculated annual dose-rates yielded a set of 18 age-estimates. For some samples complementary dates were obtained using high temperature TL (HTTL) of plagioclase feldspars. These latter dates combined with previously determined radiocarbon and unspiked K-Ar dates were used to explore the validity of ages computed from the TL of quartz. Individual values for quartz appear to be scattered and do not match ages deduced from {sup 14}C, unspiked K-Ar or HTTL on plagioclase dates. These results indicate that when conventional TL methodologies derived from the inclusion method are applied to volcanic quartz major dating problems are to be expected.

CT findings of portal vein aneurysm

International Nuclear Information System (INIS)

Yang, Dal Mo; Chang, Mi Son; Yoon, Myung Hwan; Kim, Hak Soo; Kim, Hyung Sik; Chung, Hyo Sun; Chung, Jin Woo

1999-01-01

To describe the CT findings of portal vein aneurysm in eight patients. All patients included in this study (two men and six women) underwent CT examinations between October 1996 and June1998. Of these eight, three were suffering from hepatic disease and portal hypertension. We determined the location, shape, size, and characteristics of the lesions, and the presence or absence of portal vein anomaly. Seven patients had intrahepatic portal vein aneurysm (at the umbilical portion of the left portal vein in five patients, between the transverse and umbilical portion of the left portal vein in one, and at the bifurcation of the anterior and posterior branch of the right portal vein in one), while extrahepatic portal vein aneurysm, at the confluence of the superior mesenteric and splenic vein was found in only one. Lesions were cyst-shaped in seven cases and saccular in one, and showed well-circumscribed, markedly enhanced mass, which communicated with the portal vein and/or gives off major branches. Portal vein anomaly, in which the right anterior segmental portal vein originated from the umbilical portion of the left portal vein, was seen in three patients. In all three, intrahepatic portal vein aneurysm was present at the umbilical portion of the left portal vein, and in one, the umbilical protion of the left portal vein was located to the right of the Cantlic line. CT examination can help reveal portal vein aneurysm by detecting a well-circumscribed, markedly enhanced mass which communicates with the portal vein and/or gives off major branches

Production of quartz plates for CMS-CASTOR Experiment

CERN Document Server

Adiguzel, Aytul; Ayhan, Aydin; Bakirci, Mustafa Numan; Basegmez, Suzan; Beaumont, Willem; Borras, Kerstin; Campbell, Alan; De Paula Carvalho, W; Çerçi, Salim; De Jesus Damiao, Dilson; Dogangün, O; Dumanoglu, Isa; d'Enterria, David; Erchov, Y; Eskut, Eda; Figueiredo, D; Girgis, Semiray; Göttlicher, P; Gouskos, Loukas; Gurpinar, Emine; Hos, Ilknur; Katkov, Igor; Katsas, Panagiotis; Khein, Lev; Knutsson, Albert; Kuznetsov, Andrey; Lebeau, Michel; Van Mechelen, Pierre; Muhl, Carsten; Musienko, Yuri; Ochesanu, Silvia; Onengüt, G; Onengut, G Jr; Ozdemir, Kadri; Panagiotou, Apostolos; Polatoz, A; Ripert, Marion; Shileev, K; Sogut, Kenan; Tiflov, B TaliV; Kayis-Topaksu, A; Uzun, Dilber

2008-01-01

Light transmission rate performance of $102$ irradiated quartz samples was measured to select the best quartz plates for CMS-CASTOR calorimeter. All the produced quartz plates were originally used in a previous CERN experiment, DELPHI. Three different doses of $^{60}$Co source were used with the collaboration of PSI (Paul Scherrer Institute, Villigen PSI, Switzerland.) to study the transmission rate performance of the quartz samples after irradiation for different incident light, ranging from $250$ to $700$ nm in $5$ nm increasing steps. All samples show different decrease in the rate with wavelength for different doses. Three different steps were followed before irradiation to find out the best way of cleaning the original DELPHI Cu/Cr tracks on the samples. Results of these measurements presented here correspond to the quartz plates that will be used in one hadronic sector of CASTOR calorimeter until end of 2008. For the full calorimeter new quartz plates will be installed. We also present the light transmi...

Mechanical and optical nanodevices in single-crystal quartz

Science.gov (United States)

Sohn, Young-Ik; Miller, Rachel; Venkataraman, Vivek; Lončar, Marko

2017-12-01

Single-crystal α-quartz, one of the most widely used piezoelectric materials, has enabled a wide range of timing applications. Owing to the fact that an integrated thin-film based quartz platform is not available, most of these applications rely on macroscopic, bulk crystal-based devices. Here, we show that the Faraday cage angled-etching technique can be used to realize nanoscale electromechanical and photonic devices in quartz. Using this approach, we demonstrate quartz nanomechanical cantilevers and ring resonators featuring Qs of 4900 and 8900, respectively.

Major Brazilian gold deposits - 1982 to 1999

Science.gov (United States)

Thorman, Charles H.; DeWitt, Ed; Maron, Marcos A.; Ladeira, Eduardo A.

2001-07-01

Brazil has been a major but intermittent producer of gold since its discovery in 1500. Brazil led the world in gold production during the 18th and early 19th centuries. From the late 19th century to the late 20th century, total mining company and garimpeiro production was small and relatively constant at about 5 to 8 t/year. The discovery of alluvial deposits in the Amazon by garimpeiros in the 1970s and the opening of eight mines by mining companies from 1983 to 1990 fueled a major boom in Brazil's gold production, exceeding 100 t/year in 1988 and 1989. However, garimpeiro alluvial production decreased rapidly in the 1990s, to about 10 t/year by 1999. Company production increased about tenfold from about 4 t/year in 1982 to 40 t in 1992. Production from 1992 to the present remained relatively stable, even though several mines were closed or were in the process of closing and no new major mines were put into production during that period. Based on their production history from 1982-1999, 17 gold mines are ranked as major (>20 t) and minor (3-8 t) mines. From 1982-1999, deposits hosted in Archean rocks produced 66% of the gold in Brazil, whereas deposits in Paleoproterozoic and Neoproterozoic rocks accounted for 19% and 15%, respectively. Deposits in metamorphosed sedimentary rocks, especially carbonate-rich rocks and carbonate iron-formation, yielded the great bulk of the gold. Deposits in igneous rocks were of much less importance. The Archean and Paleoproterozoic terranes of Brazil largely lack base-metal-rich volcanogenic massive sulfide deposits, porphyry deposits, and polymetallic veins and sedimentary exhalative deposits. An exception to this is in the Carajás Mineral Province.

Major brazilian gold deposits - 1982 to 1999

Science.gov (United States)

Thorman, C.H.; Dewitt, E.; Maron, M.A.; Ladeira, E.A.

2001-01-01

Brazil has been a major but intermittent producer of gold since its discovery in 1500. Brazil led the world in gold production during the 18th and early 19th centuries. From the late 19th century to the late 20th century, total mining company and garimpeiro production was small and relatively constant at about 5 to 8 t/year. The discovery of alluvial deposits in the Amazon by garimpeiros in the 1970s and the opening of eight mines by mining companies from 1983 to 1990 fueled a major boom in Brazil's gold production, exceeding 100 t/year in 1988 and 1989. However, garimpeiro alluvial production decreased 'rapidly in the 1990s, to about 10 t/year by 1999. Company production increased about tenfold from about 4 t/year in 1982 to 40 t in 1992. Production from 1992 to the present remained relatively stable, even though several mines were closed or were in the process of closing and no new major mines were put into production during that period. Based on their production history from 1982-1999, 17 gold mines are ranked as major (> 20 t) and minor (3-8 t) mines. From 1982-1999, deposits hosted in Archean rocks produced 66% of the gold in Brazil, whereas deposits in Paleoproterozoic and Neoproterozoic rocks accounted for 19% and 15%, respectively. Deposits in metamorphosed sedimentary rocks, especially carbonate-rich rocks and carbonate iron-formation, yielded the great bulk of the gold. Deposits in igneous rocks were of much less importance. The Archean and Paleoproterozoic terranes of Brazil largely lack base-metal-rich volcanogenic massive sulfide deposits, porphyry deposits, and polymetallic veins and sedimentary exhalative deposits. An exception to this is in the Caraja??s Mineral Province.

Gold surface supported spherical liposome-gold nano-particle nano-composite for label free DNA sensing.

Science.gov (United States)

Bhuvana, M; Narayanan, J Shankara; Dharuman, V; Teng, W; Hahn, J H; Jayakumar, K

2013-03-15

Immobilization of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) liposome-gold nano-particle (DOPE-AuNP) nano-composite covalently on 3-mercaptopropionic acid (MPA) on gold surface is demonstrated for the first time for electrochemical label free DNA sensing. Spherical nature of the DOPE on the MPA monolayer is confirmed by the appearance of sigmoidal voltammetric profile, characteristic behavior of linear diffusion, for the MPA-DOPE in presence of [Fe(CN)(6)](3-/4-) and [Ru(NH(3))(6)](3+) redox probes. The DOPE liposome vesicle fusion is prevented by electroless deposition of AuNP on the hydrophilic amine head groups of the DOPE. Immobilization of single stranded DNA (ssDNA) is made via simple gold-thiol linkage for DNA hybridization sensing in the presence of [Fe(CN)(6)](3-/4-). The sensor discriminates the hybridized (complementary target hybridized), un-hybridized (non-complementary target hybridized) and single base mismatch target hybridized surfaces sensitively and selectively without signal amplification. The lowest target DNA concentration detected is 0.1×10(-12)M. Cyclic voltammetry (CV), electrochemical impedance (EIS), differential pulse voltammetry (DPV) and quartz crystal microbalance (QCM) techniques are used for DNA sensing on DOPE-AuNP nano-composite. Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Ultraviolet-Visible (UV) spectroscopic techniques are used to understand the interactions between the DOPE, AuNP and ssDNA. The results indicate the presence of an intact and well defined spherical DOPE-AuNP nano-composite on the gold surface. The method could be applied for fabrication of the surface based liposome-AuNP-DNA composite for cell transfection studies at reduced reagents and costs. Copyright © 2012 Elsevier B.V. All rights reserved.

A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy Applications

Directory of Open Access Journals (Sweden)

Tomasz Starecki

2017-11-01

Full Text Available All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations. Taking into consideration that QEPAS sensors are based on quartz tuning forks, and that quartz has a relatively high voltage constant and relatively low charge constant, it seems that a transimpedance amplifier is not an optimal solution. This paper describes the design of a quartz QEPAS sensor preamplifier, implemented with voltage amplifier configuration. Discussion of an electrical model of the circuit and preliminary measurements are presented. Both theoretical analysis and experiments show that use of the voltage configuration allows for a substantial increase of the output signal in comparison to the transimpedance circuit with the same tuning fork working in identical conditions. Assuming that the sensitivity of the QEPAS technique depends directly on the properties of the preamplifier, use of the voltage amplifier configuration should result in an increase of QEPAS sensitivity by one to two orders of magnitude.

A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy) Applications.

Science.gov (United States)

Starecki, Tomasz; Wieczorek, Piotr Z

2017-11-03

All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS) applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations. Taking into consideration that QEPAS sensors are based on quartz tuning forks, and that quartz has a relatively high voltage constant and relatively low charge constant, it seems that a transimpedance amplifier is not an optimal solution. This paper describes the design of a quartz QEPAS sensor preamplifier, implemented with voltage amplifier configuration. Discussion of an electrical model of the circuit and preliminary measurements are presented. Both theoretical analysis and experiments show that use of the voltage configuration allows for a substantial increase of the output signal in comparison to the transimpedance circuit with the same tuning fork working in identical conditions. Assuming that the sensitivity of the QEPAS technique depends directly on the properties of the preamplifier, use of the voltage amplifier configuration should result in an increase of QEPAS sensitivity by one to two orders of magnitude.

The influence of the dimensions of electrodes on the frequency-temperature characteristics of at and BT-cut quartz resonators

International Nuclear Information System (INIS)

Zelenka, J.

1996-01-01

The comparison of the measured resonant frequency-temperature characteristics of the AT-and BT-cut square and circular quartz resonators with the computed ones is given in the paper. The curves which express the frequency-temperature behavior of the resonators are compared. The influence of the thickness of the silver and gold electrodes on the first order frequency temperature coefficient is presented. The influence of the dimension ratio of the wafer on the orientation for which the zero first order temperature coefficient occurs at the temperature T O = 25 O C are given. (authors)

Measurement of natural radioactivity in granites and its quartz-bearing gold at El-Fawakhir area (Central Eastern Desert, Egypt

Directory of Open Access Journals (Sweden)

M.A.M. Uosif

2015-07-01

Full Text Available The distribution of natural radionuclides (226Ra, 232Th and 40K in Granites and its quartz-bearing gold at El-Fawakhir area (Central Eastern Desert, Egypt were measured by using γ-ray spectroscopy [NaI (Tl 3″ × 3″]. X-Ray Fluorescence technique was used for chemical analyses of the studied samples. The specific activity of 226Ra, 232Th and 40K values are in range (3 ± 0.5 to 43 ± 2 Bqkg−1, (5 ± 0.7 to 41 ± 2 Bqkg−1 and (128 ± 6 to 682 ± 35 Bqkg−1 respectively. The absorbed dose rates ranged from 13.8 to 58.4 nGy h−1, where the total effective dose rates were determined to be between 16.7 and 70.9 μSvy−1. The maximum external hazard index (Hex is 0.3 nGyh−1. The calculated values of the excess lifetime cancer risks (ELCR and annual effective dose rate values are in between (8.48 × 10−5 and 2.63 × 10−4 and (24.2 and 72.9 μSvy−1 respectively. Geochemically, the studied granites consist of major oxides, they are characterized by SiO2, K2O, Na2O, Al2O3, and depleted in CaO, MgO, TiO2, and P2O5. The average absorbed dose rate (Do in air is 37.8 nGyh−1 for the whole studied samples, this value is about 3.78% of the 1.0 mSvy−1 recommended by (ICRP-60,1991 to the public, so there is no radiological risk for the workers in that area.

Quartz exposure and increased respiratory symptoms among coal ...

African Journals Online (AJOL)

Quartz has been an inevitable composition of different type of coal mined. The quartz exposures among coalmine workers has been attributed to activities such as cutting the adjacent rock, the roof, the floor and the intrusions. Objective: The aim of the study is to determine the associations between quartz exposures and ...

Comparison between mechanical properties of human saphenous vein and umbilical vein

Directory of Open Access Journals (Sweden)

Hamedani Borhan

2012-08-01

Full Text Available Abstract Background As a main cause of mortality in developed countries, Coronary Artery Disease (CAD is known as silent killer with a considerable cost to be dedicated for its treatment. Coronary Artery Bypass Graft (CABG is a common remedy for CAD for which different blood vessels are used as a detour. There is a lack of knowledge about mechanical properties of human blood vessels used for CABG, and while these properties have a great impact on long-term patency of a CABG. Thus, studying these properties, especially those of human umbilical veins which have not been considered yet, looks utterly necessary. Methods Umbilical vein, as well as human Saphenous vein, are respectively obtained after cesarean and CABG. First, histological tests were performed to investigate different fiber contents of the samples. Having prepared samples carefully, force-displacement results of samples were rendered to real stress–strain measurements and then a fourth-order polynomial was used to prove the non-linear behavior of these two vessels. Results Results were analyzed in two directions, i.e. circumferentially and longitudinally, which then were compared with each other. The comparison between stiffness and elasticity of these veins showed that Saphenous vein’s stiffness is much higher than that of umbilical vein and also, it is less stretchable. Furthermore, for both vessels, longitudinal stiffness was higher than that of circumferential and in stark contrast, stretch ratio in circumferential direction came much higher than longitudinal orientation. Conclusion Blood pressure is very high in the region of aorta, so there should be a stiff blood vessel in this area and previous investigations showed that stiffer vessels would have a better influence on the flow of bypass. To this end, the current study has made an attempt to compare these two blood vessels’ stiffness, finding that Saphenous vein is stiffer than umbilical vein which is somehow as stiff as

Vein grafting in fingertip replantations.

Science.gov (United States)

Yan, Hede; Jackson, William D; Songcharoen, Somjade; Akdemir, Ovunc; Li, Zhijie; Chen, Xinglong; Jiang, Liangfu; Gao, Weiyang

2009-01-01

In this retrospective study, the survival rates of fingertip replantation with and without vein grafting were evaluated along with their postoperative functional and cosmetic results. One hundred twenty-one-fingertip amputations were performed in 103 patients between September 2002 and July 2007. Thirty-four amputated fingertips were replanted without vein grafting, while 87 amputated fingertips were replanted with vein grafting for arterial and/or venous repairs. The overall survival rates of the replantations with and without vein grafting were 90% (78/87) and 85% (29/34), respectively. The survival rates were 88% (36/41) with venous repair, 93% (25/27) with arterial repair, and 89% (17/19) with both. Nineteen patients without vein grafting and 48 patients with vein grafting had a follow-up period of more than one year. Good cosmetic and functional outcomes were observed in both groups of patients. The results show that vein grafting is a reliable technique in fingertip replantations, showing no significant difference (P > 0.05) in survival between those with and without vein grafting. Furthermore, no significant difference (P > 0.05) in survival was found between cases with vein grafts for arterial and/or venous repairs. In fingertip replantations with vein grafting, favorable functional and esthetic results can be achieved without sacrificing replantation survival. (c) 2009 Wiley-Liss, Inc.

Microwave GaAs Integrated Circuits On Quartz Substrates

Science.gov (United States)

Siegel, Peter H.; Mehdi, Imran; Wilson, Barbara

1994-01-01

Integrated circuits for use in detecting electromagnetic radiation at millimeter and submillimeter wavelengths constructed by bonding GaAs-based integrated circuits onto quartz-substrate-based stripline circuits. Approach offers combined advantages of high-speed semiconductor active devices made only on epitaxially deposited GaAs substrates with low-dielectric-loss, mechanically rugged quartz substrates. Other potential applications include integration of antenna elements with active devices, using carrier substrates other than quartz to meet particular requirements using lifted-off GaAs layer in membrane configuration with quartz substrate supporting edges only, and using lift-off technique to fabricate ultrathin discrete devices diced separately and inserted into predefined larger circuits. In different device concept, quartz substrate utilized as transparent support for GaAs devices excited from back side by optical radiation.

Experimental study of quartz inclusions in garnet at pressures up to 3.0 GPa: evaluating validity of the quartz-in-garnet inclusion elastic thermobarometer

Science.gov (United States)

Thomas, Jay B.; Spear, Frank S.

2018-05-01

Garnet crystals with quartz inclusions were hydrothermally crystallized from oxide starting materials in piston-cylinder apparatuses at pressures from 0.5 to 3 GPa and temperatures ranging from 700 to 800 °C to study how entrapment conditions affect remnant pressures of quartz inclusions used for quartz-in-garnet (QuiG) elastic thermobarometry. Systematic changes of the 128, 206 and 464 cm-1 Raman band frequencies of quartz were used to determine pressures of quartz inclusions in garnet using Raman spectroscopy calibrations that describe the P-T dependencies of Raman band shifts for quartz under hydrostatic pressure. Within analytical uncertainties, inclusion pressures calculated for each of the three Raman band frequencies are equivalent, which suggests that non-hydrostatic stress effects caused by elastic anisotropy in quartz are smaller than measurement errors. The experimental quartz inclusions have pressures ranging from - 0.351 to 1.247 GPa that span the range of values observed for quartz inclusions in garnets from natural rocks. Quartz inclusion pressures were used to model P-T conditions at which the inclusions could have been trapped. The accuracy of QuiG thermobarometry was evaluated by considering the differences between pressures measured during experiments and pressures calculated using published equation of state parameters for quartz and garnet. Our experimental results demonstrate that Raman measurements performed at room temperature can be used without corrections to estimate garnet crystallization pressures. Calculated entrapment pressures for quartz inclusions in garnet are less than 10% different from pressures measured during the experiments. Because the method is simple to apply with reasonable accuracy, we expect widespread usage of QuiG thermobarometry to estimate crystallization conditions for garnet-bearing silicic rocks.

Surface complexation modelling: Experiments on sorption of nickel on quartz, goethite and kaolinite and preliminary tests on sorption of thorium on quartz

Energy Technology Data Exchange (ETDEWEB)

Puukko, E.; Hakanen, M. [Univ. of Helsinki (Finland). Dept. of Chemistry. Lab. of Radiochemistry

1997-09-01

The aim of the work was to study the sorption behaviour of Ni on quartz, goethite and kaolinite at different pH levels and in different electrolyte solutions of different strength. In addition preliminary experiments were made to study the sorption of thorium on quartz. The MUS quartz and Nilsiae quartz were analysed for MnO{sub 2} by neutron activation analysis (NAA) and the experimental results were modelled with the HYDRAQL computer model. 9 refs.

Mineralized breccia clasts: a window into hidden porphyry-type mineralization underlying the epithermal polymetallic deposit of Cerro de Pasco (Peru)

Science.gov (United States)

Rottier, Bertrand; Kouzmanov, Kalin; Casanova, Vincent; Bouvier, Anne-Sophie; Baumgartner, Lukas P.; Wälle, Markus; Fontboté, Lluís

2018-01-01

Cerro de Pasco (Peru) is known for its large epithermal polymetallic (Zn-Pb-Ag-Cu-Bi) mineralization emplaced at shallow level, a few hundred meters below the paleo-surface, at the border of a large diatreme-dome complex. Porphyry-style veins crosscutting hornfels and magmatic rock clasts are found in the diatreme breccia and in quartz-monzonite porphyry dikes. Such mineralized veins in clasts allow investigation of high-temperature porphyry-style mineralization developed in the deep portions of magmatic-hydrothermal systems. Quartz in porphyry-style veins contains silicate melt inclusions as well as fluid and solid mineral inclusions. Two types of high-temperature (> 600 °C) quartz-molybdenite-(chalcopyrite)-(pyrite) veins are found in the clasts. Early, thin (1-2 mm), and sinuous HT1 veins are crosscut by slightly thicker (up to 2 cm) and more regular HT2 veins. The HT1 vein quartz hosts CO2- and sulfur-rich high-density vapor inclusions. Two subtypes of the HT1 veins have been defined, based on the nature of mineral inclusions hosted in quartz: (i) HT1bt veins with inclusions of K-feldspar, biotite, rutile, and minor titanite and (ii) HT1px veins with inclusions of actinolite, augite, titanite, apatite, and minor rutile. Using an emplacement depth of the veins of between 2 and 3 km (500 to 800 bar), derived from the diatreme breccia architecture and the supposed erosion preceding the diatreme formation, multiple mineral thermobarometers are applied. The data indicate that HT1 veins were formed at temperatures > 700 °C. HT2 veins host assemblages of polyphase brine inclusions, generally coexisting with low-density vapor-rich inclusions, trapped at temperatures around 600 °C. Rhyolitic silicate melt inclusions found in both HT1 and HT2 veins represent melt droplets transported by the ascending hydrothermal fluids. LA-ICP-MS analyses reveal a chemical evolution coherent with the crystallization of an evolved rhyolitic melt. Quartz from both HT1 and HT2 veins

Identifying well-bleached quartz using the different bleaching rates of quartz and feldspar luminescence signals

DEFF Research Database (Denmark)

Murray, A.S.; Thomsen, Kristina Jørkov; Masuda, N.

2012-01-01

When dating older sedimentary deposits using quartz, there are no unambiguous methods for identifying the presence of incomplete bleaching. Current statistical analysis of dose distributions depends entirely on the assumption that incomplete bleaching and mixing are the main causes of any excess...... dispersion in the distribution; the only existing way to test this assumption is using independent age control. Here we suggest a new approach to this question, based on the differential bleaching rates of quartz and feldspar luminescence signals. We first present data that confirm the differences...... in relative bleaching rates of quartz optically stimulated luminescence (OSL) and feldspar luminescence stimulated at 50 °C by infrared light (IR50) and feldspar luminescence stimulated at 290 °C by infrared light after a stimulation at 50 °C (pIRIR290), and use recently deposited samples to determine...

Vein matching using artificial neural network in vein authentication systems

Science.gov (United States)

Noori Hoshyar, Azadeh; Sulaiman, Riza

2011-10-01

Personal identification technology as security systems is developing rapidly. Traditional authentication modes like key; password; card are not safe enough because they could be stolen or easily forgotten. Biometric as developed technology has been applied to a wide range of systems. According to different researchers, vein biometric is a good candidate among other biometric traits such as fingerprint, hand geometry, voice, DNA and etc for authentication systems. Vein authentication systems can be designed by different methodologies. All the methodologies consist of matching stage which is too important for final verification of the system. Neural Network is an effective methodology for matching and recognizing individuals in authentication systems. Therefore, this paper explains and implements the Neural Network methodology for finger vein authentication system. Neural Network is trained in Matlab to match the vein features of authentication system. The Network simulation shows the quality of matching as 95% which is a good performance for authentication system matching.

Absence of Middle Hepatic Vein Combined with Retro-Aortic Left Renal Vein: a Very Rare Case Report

Directory of Open Access Journals (Sweden)

Sezer Akçer

2012-06-01

Full Text Available The hepatic and renal veins drain into the inferior vena cava. The upper group of hepatic veins consists of three veins which extend to the posterior face of the liver to join the inferior cava. The left renal vein passes anterior to the aorta just below the origin of the superior mesenteric artery. We detected a variation in the hepatic and renal veins in a multislice CT angiogram of a nine-year-old male patient in the Radiology Department of Afyon Kocatepe University Medical School. The upper group hepatic veins normally drains into the inferior vena cava as three separate trunks, namely the right, left and middle. In our case, we found that only the right and left hepatic veins existed and the middle hepatic vein was absent. Furthermore, the left renal vein, which normally passes anterior to the abdominal aorta, was retro-aortic. Left renal vein variations are of great importance in planning retroperitoneal surgery and vascular interventions. Knowledge of a patient’s hepatic vein and renovascular anatomy and determining their variations and anomalies are of critical importance to abdominal operations, transplantations and preoperative evaluation of endovascular interventions.

Surgical Access to Jejunal Veins for Local Thrombolysis and Stent Placement in Portal Vein Thrombosis

International Nuclear Information System (INIS)

Schellhammer, Frank; Esch, Jan Schulte am; Hammerschlag, Sascha; Knoefel, Wolfram Trudo; Fuerst, Guenter

2008-01-01

Portal vein thrombosis is an infrequent entity, which may cause high morbidity and mortality. We report a case of portal vein thrombosis due to benign stenosis following partial pancreatoduodenectomy with segmental replacement of the portal vein by a Gore-tex graft. Using a surgical access to jenunal veins, local thrombolysis, mechanical fragmentation of thrombus, and stent placement were successfully performed.

Mercury pollution from the artisanal mining in Yani gold district, Northern Bolivia

Science.gov (United States)

Alfonso, Pura; Freixas, Anna; Bascompta, Marc; María Aranibar, Ana; Villegas, Karla; María García-Noguero, Eva; Higueras, Pablo; Cielito Saraiva, Angela

2016-04-01

Artisanal gold mining is the main economic activity in the Yani district, Northern Bolivia. In this area abundant orogenic gold deposits constituted by quartz veins hosted in paleozoic turbiditic series that contain either free gold or associated with pyrite. Gold is recovered in processing plants by gravimetric methods using shaking tables in several communities of this district. Previously, miners ground the mineral in ball mills together with mercury. The present study aims to evaluate the effect of mercury used in the gold recovering process to the environment and human health in the Yani district. The assessment was based on the analysis of human hair, sediments and water from the river nearby the processing plant and drinking water from the fountain that supplies these communities. 47 samples of hair from miners and other people from the Yani and Señor de Mayo communities were obtained in 2014 and 52 samples in 2015. All were analysed to evaluate the mercury exposure in these places. The results from the 2014 sampling show a wide range of Hg concentration in hair, especially in Señor de Mayo, with values up to 136 μg/g THg. However, in 2015 among the 43 residents in Señor de Mayo, 29 (67%) exhibit concentrations higher than 2 μg/g THg, with an average value of 5.36 μg/g THg. On the other hand, in Yani only 40% have concentrations above 2 μg/g THg, with an average value of 2.34 μg/g THg. The content in Hg in most of the hair samples exhibit values above the tolerable limits established by the US Environmental Protection Agency (1 μg/g Hg) and the World Health Organisation (WHO, 2 μg/g Hg). These high Hg concentrations are found not only in miners but also in the other members of the community, in spite of low fish consumption in this area. Part of the hair was analysed before and after cleaning. Usually in the second case the content of Hg is reduced, but still show high Hg levels, then probably the atmosphere is polluted with Hg and population is

Uptake of gold nanoparticles in primary human endothelial cells

DEFF Research Database (Denmark)

Klingberg, Henrik; Oddershede, Lene B.; Löschner, Katrin

2015-01-01

Gold nanoparticles (AuNPs) are relevant in nanomedicine for drug delivery in the vascular system, where endothelial cells are the first point of contact. We investigated the uptake of 80 nm AuNPs in primary human umbilical vein endothelial cells (HUVECs) by flow cytometry, 3D confocal microscopy......–3 or more particles. Pre-treatment with chlorpromazine inhibited the AuNP-uptake in HUVECs, indicating that internalisation occurred mainly by clathrin-mediated endocytosis. Cell activation by exposure to tumour necrosis factor or lipopolysaccharide had a slight or no effect on the uptake of Au...

Red and blue colouration of thermoluminescence from natural quartz sands

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, T; Hayashi, Y; Koyanagi, A; Yokosaka, K; Kimura, K

1986-01-01

Quartz extracts, from a pegmatite rock, volcanic ashes and beach sands, were exposed to X-rays or gamma-rays upto 8.8kGy. The irradiated sands were observed through a thermoluminescence colour image technique (abbreviated to TLCI by the authors) using highly sensitive colour photographic system. The quartz sands from volcanic ash layers, containing ..beta..-quartz (mineralized at high temperature), always indicate a red TLCI, whereas the quartz rocks from pegmatite origin and granite strata, containing ..cap alpha..-quartz (mineralized at low temperature), gave a typical blue TLCI, being consistent with the well known quartz TL colour. Quartz fractions from the beach sands showed a mixture of both red and blue TLCI, probably reflecting the respective mixtures of ..beta..-(in their origin) and ..cap alpha..-quartz fractions along the riverside area. The search using X-ray diffractometry and instrumental neutron activation analysis proved that the cause of distinctly different colourations was attributable to the impurity atoms: light rare earth elements (Eu and/or Sm) bringing on red TLCI, while structural defects yielding the blue TLCI).

Gamma irradiation of quartz from Pannier basin, South America

Energy Technology Data Exchange (ETDEWEB)

Enokihara, Cyro T.; Rela, Paulo R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], E-mail: cteiti@ipen.br, E-mail: prela@ipen.br; Guttler, Rainer A.S. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias

2007-07-01

The use of gamma radiation to induce or enhance color centers in gemstones is a widespread technique and applied worldwide on a industrial scale since at least 1970. The presence of defects and defect structures in quartz from a border region of southern Brazil and Uruguay are the reason for the creation of a new color variety of quartz called 'Prasiolite' in the gem trade. This quartz has a pleasant green color produced by gamma irradiation. The procedures of irradiation at IPEN show that the activation of these color producing defects can be monitored by detailed chemical and spectroscopic analysis. For the first time UV-VIS-NIR spectra of this new color variety of quartz are shown. They revealed special features of these quartz crystals coming from basaltic terranes of the Parana Basin. Contrary to most specimen of quartz from other parts of Brazil, they have such a high water and OH content that they resemble more chalcedony or opal, but not highly crystalline quartz specimens. The cause of the color are broken bonds of Si-OH defining the so-called dangling bonds. (author)

A statistical analysis of mineral relationships in a Witwatersrand gold placer at Randfontein Estates

International Nuclear Information System (INIS)

Tucker, R.F.

1983-01-01

The Proterozoic 'Composite Reef' on the Randfontein Estates Gold Mine, is a proximal Witwatersrand braided-stream placer, in which pyrite, chromite, zircon, uraninite, and gold are the more common detrital minerals. They range in concentration from a few ppm to over 3 per cent. Optimum concentration of these minerals occurs on scour- and pebble-armoured surfaces, in conglomerate gravel bars, and in trough cross-bedded quartz-arenites. The distribution of gold is, however, complex and the relative proportions of the detrital minerals change from one depositional situation to another. The abundance of detrital and other related minerals was monitored geochemically and quantitatively indicates the prevalence of optimal placer concentration situations in preserved depositional subenvironments of the 'Composite Reef'. The relationships between 20 elements were determined by using an R-mode factor-analysis of the geochemical data. The elements load on to chalcophile, detrital oxide, hydrothermal and clay factors, suggesting the consanguinity of four subsets of elements. A multiple linear regression of gold against the other elements provides the framework for an improved prediction of gold where only very small or single samples are available. The method uses many elements in a single sample to achieve statistical reliability, as opposed to the geostatistical method where many samples of a single element are analysed. The regression equation demonstrates the geochemical validity of the geological-response model for optimum gold mineralization

Post-magmatic structural evolution of the Troodos Ophiolite Pillow Lavas revealed by microthermometry within vein precipitates, with application to Alpine-Mediterranean supra-subduction zone settings

Science.gov (United States)

Kurz, W.; Quandt, D.; Micheuz, P.; Krenn, K.

2017-12-01

The Troodos ophiolite, Cyprus, is one of the best preserved ophiolites. Based on geochemical data a supra-subduction zone (SSZ) setting was proposed. Microtextures and fluid inclusions of veins and vesicles within the Pillow Lavas record the post-magmatic structural and geochemical evolution of this SSZ beginning at 75 Ma. Three different vein types from the Upper and Lower Pillow Lavas are distinguished and imply vein precipitation under a dominant extensional regime: (1) syntaxial calcite-, quartz- and zeolite-bearing veins are interpreted as mineralized extension fractures that were pervaded by seawater. This advective fluid flow in an open system changed later into a closed system characterized by geochemical self-organization. (2) Blocky and (3) antitaxial fibrous calcite veins are associated with brecciation due to hydrofracturing and diffusion-crystallization processes, respectively. Based on aqueous fluid inclusion chemistry with seawater salinities in all studied vein types, representative fluid inclusion isochores crossed with calculated litho- and hydrostatic pressure conditions yield mineral precipitation temperatures between 180 and 210 °C, for veins and vesicles hosted in the Upper and Lower Pillow Lavas. This points to a heat source for the circulating seawater and implies that vein and vesicle minerals precipitated shortly after pillow lava crystallization under dominant isobaric cooling conditions. Compared to previous suggestions derived from secondary mineralization a less steep geothermal gradient of 200 °C from the Sheeted Dyke Complex to the Pillow Lavas of the Troodos SSZ is proposed. Further fossil and recent SSZ like the Mirdita ophiolite, Albania, the South-Anatolian ophiolites, Turkey, and the Izu-Bonin fore arc, respectively, reveal similar volcanic sequences. Vein samples recovered during International Ocean Discovery Program expedition 351 and 352 in the Izu-Bonin back and fore arc, respectively, indicate also seawater infiltration

TL response to quartz and aluminum oxide grain for α-irradiation

International Nuclear Information System (INIS)

Pan Baolin; Wei Mingjian; Li Dongxu; Liu Zhaowen; Liu Chao; Zhao Shiyuan

2009-01-01

Thermoluminescence (TL) response for an α-ray irradiation system ( 241 Am) was examined with quartz grains of 11-40 μm. Quartz grains of different sizes, i.e. 137 Cs), before they were irradiated to different doses by the α-ray irradiation system. TL response to the quartz grain samples was measured. TL response of the quartz grains smaller than 4 μm and 11-40 μm to α-ray irradiation is the best, as the α-rays cannot penetrate quartz larger than 40 μm. The TL response characteristic is related with quartz grain surface area. TL responses to α-irradiation of 11-40 μm quartz and aluminum oxide grains were compared. The α-irradiation TL response of aluminum oxide (330 degree C) is better than the quartz (375 degree C). (authors)

The economics of vein disease.

Science.gov (United States)

Sales, Clifford M; Podnos, Joan; Levison, Jonathan

2007-09-01

The management of cosmetic vein problems requires a very different approach than that for the majority of most other vascular disorders that occur in a vascular surgery practice. This article focuses on the business aspects of a cosmetic vein practice, with particular attention to the uniqueness of these issues. Managing patient expectations is critical to the success of a cosmetic vein practice. Maneuvering within the insurance can be difficult and frustrating for both the patient and the practice. Practices should use cost accounting principles to evaluate the success of their vein work. Vein surgery--especially if performed within the office--can undergo an accurate break-even analysis to determine its profitability.

Scaly fabrics and veins of the Mugi and Makimine mélanges in the Shimanto belt, SW Japan

Science.gov (United States)

Ramirez, G. E.; Fisher, D. M.; Yamaguchi, A.; Kimura, G.

2016-12-01

Two regionally extensive ancient subduction fault zones provide a microstructural record of the plate boundary deformation associated with underthrusting. These rocks exhibit many of the characteristics associated with exposed ancient subduction fault zones worldwide, including: (1) σ1 is near orthogonal to the deformation fabric (2) there are microstructurally pervasive quartz and calcite filled veins concentrated in coarser blocks and along extensional jogs on slip surfaces, (3) evidence for local diffusion of silica sourced from web-like arrays of slip surfaces (i.e., scaly fabrics), and (4) evidence for cycles of cracking and sealing that record cyclic variations in stress. We present new backscatter SEM observations of scaly fabrics from two ancient subduction-related shear zones from the Shimanto Belt in Japan that exemplify these characteristics and represent the full temperature range of the seismogenic zone: 1) the Mugi mélange (lower ( 130-150 °C) and upper ( 170-200 °C) sections) and 2) Makimine mélange (peak temperatures of 340 °C). The Mugi mélange is an underplated duplex consisting of two horses separated by an OOST. The upper section is bounded at the top by a pseudotachylite-bearing paleodécollement. The Makimine mélange was underplated at the downdip limit of the seismogenic zone. The scaly fabrics associated with these shear zones display significantly different microstructural characteristics. A slip surface from along the upper Mugi is characterized by broader ( 20-30 μm), zones of quartz-poor, anastomosing shear zones composed of fine-grained (0.5-2 μm in length) phyllosilicates. The Makimine mélange exhibits thinner (10-20 μm), anastomosing shear zones with coarser (1-4 μm in length) phyllosilicate grains that are more strongly oriented into parallelism with slip surfaces. Quartz veins are pervasively developed in more competent blocks and are oriented at near perpendicular angles to the slip surfaces. Microstructural analyses

Radiation resistivity of quartz core fiber, 3

International Nuclear Information System (INIS)

Gozen, Toshikazu; Suzuki, Toshiya; Hayashi, Tokuji; Tanaka, Hiroyuki; Okamoto, Shinichi.

1985-01-01

Radiation resistance characteristics were evaluated for a multi-mode quartz core fiber in low temperature region together with photobleaching effect depending on the incident light power and dependency on the wavelength of measuring rays. This report describes the results of the abovementioned items and the next step study of trial manufacturing of a pure-quartz single-mode fiber for the employment of longer wavelength rays and greater capacity in light transmission communication system. Quartz core fiber specimens were irradiated by 60 Co γ-ray source at -55 deg C to 80 deg C in a constant temperature bath and light transmission loss was determined under irradiation conditions. Low temperature characteristics were superior in an MRT (modified rod-in tube) pure quartz fiber prepared by the plasma method as compared to VAD quartz and Ge-GI fibers. The MRT fiber showed better quality than the Ge-GI fiber also in the photobleaching effect examination. As for the wavelength dependency, light transmission loss of the MRT fiber was less than that of the Ge-GI fiber. The MRT fiber also showed a superior quality in the wide range of irradiation temperatures. Based on the above-mentioned understandings, a pure-quartz single-mode fiber of both BF 3 -doped and F-doped cladding types were developed for longer wavelengths uses. The fibers could attain low light transmission loss of less than 1.0 dB/km at 1.30 μm of wavelength. At the standpoint of radiation resistivity, the BF 3 -doped fiber was found superior. (Takagi, S.)

Deep Vein Thrombosis

African Journals Online (AJOL)

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Deep Vein Thrombosis: Risk Factors and Prevention in Surgical Patients. Deep Vein ... preventable morbidity and mortality in hospitalized surgical patients. ... the elderly.3,4 It is very rare before the age ... depends on the risk level; therefore an .... but also in the post-operative period. ... is continuing uncertainty regarding.

Noble Gas Isotope Evidence for Mantle Volatiles in the Cu-Mo Porphyry and Main Stage Polymetallic Veins at Butte, Montana

Science.gov (United States)

Hofstra, A. H.; Rusk, B. G.; Manning, A. H.; Hunt, A. G.; Landis, G. P.

2017-12-01

Recent studies suggest that volatiles released from mafic intrusions may be important sources of heat, sulfur, and metals in porphyry Cu-Mo-Au and epithermal Au-Ag deposits associated with intermediate to silicic stocks. The huge Cu-Mo porphyry and Main Stage polymetallic vein deposits at Butte are well suited to test this hypothesis because there is no geologic or isotopic evidence of basaltic intrusions in the mine or drill holes. The Butte porphyry-vein system is associated with quartz monzonite stocks and dikes within the southwest part of the Late Cretaceous Boulder batholith. The Boulder batholith was emplaced into Mesoproterozoic to Mesozoic sedimentary rocks and Late Cretaceous volcanic rocks. The Boulder batholith and Butte intrusions have Sri and eNd values indicative of crustal contamination. Eu and Ce anomalies in zircon from Butte intrusions provide evidence of oxidation due to magma degassing. To ascertain the source of volatiles in this system, 11 samples from the Cu-Mo porphyry and 16 from Main Stage veins were selected. The isotopic composition of Ar, Ne, and He extracted from fluid inclusions in quartz, magnetite, pyrite, chalcopyrite, sphalerite, galena, enargite, and covellite were determined. Helium isotopes exceed blank levels in all samples and Ne and Ar in some samples. On a 38Ar/36Ar vs. 40Ar/36Ar diagram, data plot near air. On a 20Ne/22Ne vs. 21Ne/22Ne diagram, data extend from air along the trajectories of OIB and MORB. On a 36Ar/4He vs. 3He/4He RA diagram, data extend from crust toward the air-mantle mixing line. The maximum 3He/4He RA values in the Cu-Mo porphyry (2.86) and Main Stage veins (3.46) are from pyrite and these values correspond to 36 and 43 % mantle helium. The Ne and He results show that fluid inclusions contain volatiles discharged from mantle magmas and that these volatiles were diluted by groundwater containing He derived from country rocks. Despite the lack of mafic intrusions in the Butte magmatic center, noble gas

Automated detection and classification of major retinal vessels for determination of diameter ratio of arteries and veins

Science.gov (United States)

Muramatsu, Chisako; Hatanaka, Yuji; Iwase, Tatsuhiko; Hara, Takeshi; Fujita, Hiroshi

2010-03-01

Abnormalities of retinal vasculatures can indicate health conditions in the body, such as the high blood pressure and diabetes. Providing automatically determined width ratio of arteries and veins (A/V ratio) on retinal fundus images may help physicians in the diagnosis of hypertensive retinopathy, which may cause blindness. The purpose of this study was to detect major retinal vessels and classify them into arteries and veins for the determination of A/V ratio. Images used in this study were obtained from DRIVE database, which consists of 20 cases each for training and testing vessel detection algorithms. Starting with the reference standard of vasculature segmentation provided in the database, major arteries and veins each in the upper and lower temporal regions were manually selected for establishing the gold standard. We applied the black top-hat transformation and double-ring filter to detect retinal blood vessels. From the extracted vessels, large vessels extending from the optic disc to temporal regions were selected as target vessels for calculation of A/V ratio. Image features were extracted from the vessel segments from quarter-disc to one disc diameter from the edge of optic discs. The target segments in the training cases were classified into arteries and veins by using the linear discriminant analysis, and the selected parameters were applied to those in the test cases. Out of 40 pairs, 30 pairs (75%) of arteries and veins in the 20 test cases were correctly classified. The result can be used for the automated calculation of A/V ratio.

Mineralogy, structural control and age of the Incachule Sb epithermal veins, the Cerro Aguas Calientes collapse caldera, Central Puna

Science.gov (United States)

Salado Paz, Natalia; Petrinovic, Iván; Do Campo, Margarita; Brod, José Affonso; Nieto, Fernando; da Silva Souza, Valmir; Wemmer, Klauss; Payrola, Patricio; Ventura, Roberto

2018-03-01

The Incachule Sb epithermal veins is located near to the N-E rim of the Cerro Aguas Calientes collapse caldera (17.5-10.8 Ma), in the geologic province of Puna, Salta- Argentina. It is hosted in Miocene felsic volcanic rocks with continental arc signature. The district includes twelve vein systems with mineralization of Sb occurring in hydrothermal breccias and stockwork. The veins are composed of quartz-sulfide with pyrite, stibnite and arsenopyrite. All around the veins, wall rocks are variably altered to clay minerals and sulfates in an area of around 2.5 km wide by more than 7 km long. The hydrothermal alterations recognized are: silicic, phyllic and argillic. The veins are characterized by high contents of Sb, As, and Tl and intermediate contents of Pb-Zn-Cu, and traces of Ag and Au. Homogenization and ice-melting temperatures of fluid inclusions vary from 125 °C to 189 °C and -2.4 °C to -0.8 °C. The isotopic data indicated a range of δ34S -3.04‰ to +0.72‰ consistent with a magmatic source for sulfur. We present the firsts K-Ar ages for hydrothermal illite/smectite mixed layers (I/SR1, 60% illite layers) and illite that constrain the age of the ore deposit (8.5-6.7 ± 0.2 Ma). The data shown here, let characterized the Incachule district as a shallow low sulfidation epithermal system hosted in a collapse caldera. Our data also indicate that mineralization is structurally controlled by a fault system related to the 10.3 Ma collapse of Aguas Calientes caldera. The interpreted local stress field is consistent with the regional one.

Fabrication of a novel quartz micromachined gyroscope

Science.gov (United States)

Xie, Liqiang; Xing, Jianchun; Wang, Haoxu; Wu, Xuezhong

2015-04-01

A novel quartz micromachined gyroscope is proposed in this paper. The novel gyroscope is realized by quartz anisotropic wet etching and 3-dimensional electrodes deposition. In the quartz wet etching process, the quality of Cr/Au mask films affecting the process are studied by experiment. An excellent mask film with 100 Å Cr and 2000 Å Au is achieved by optimization of experimental parameters. Crystal facets after etching seriously affect the following sidewall electrodes deposition process and the structure's mechanical behaviours. Removal of crystal facets is successfully implemented by increasing etching time based on etching rate ratios between facets and crystal planes. In the electrodes deposition process, an aperture mask evaporation method is employed to prepare electrodes on 3-dimensional surfaces of the gyroscope structure. The alignments among the aperture masks are realized by the ABM™ Mask Aligner System. Based on the processes described above, a z-axis quartz gyroscope is fabricated successfully.

Asymmetric adsorption of alanine by quartz powder from ethanol solution

Energy Technology Data Exchange (ETDEWEB)

Furuyama, Shozo; Sawada, Michio; Hachiya, Kinji; Morimoto, Tetsuo (Okayama Univ. (Japan). Faculty of Science)

1982-11-01

The asymmetric adsorption of the racemic alanine by the optically active quartz from ethanol solution at 8/sup 0/C was studied by the /sup 14/C-tracer method and the newly developed /sup 14/C-tracer ninhydrin-colorimetry combination method. The preferential adsorption of L-alanine by levorotatory quartz (l-quartz) and D-alanine by dextrorotatory quartz (d-quartz) was confirmed. The asymmetric adsorptivity (Asub(s)) falls in the range of 1.1 - 1.3, which is comparable with the value determined at - 80/sup 0/C in the previous paper. The effects of water content in the ethanol solution and of the adsorption temperature upon the adsorption affinity of alanine to quartz were also measured. The cause for the asymmetric adsorption is discussed from the crystallographic point of view.

C-Arm Computed Tomography-Assisted Adrenal Venous Sampling Improved Right Adrenal Vein Cannulation and Sampling Quality in Primary Aldosteronism.

Science.gov (United States)

Park, Chung Hyun; Hong, Namki; Han, Kichang; Kang, Sang Wook; Lee, Cho Rok; Park, Sungha; Rhee, Yumie

2018-05-04

Adrenal venous sampling (AVS) is a gold standard for subtype classification of primary aldosteronism (PA). However, this procedure has a high failure rate because of the anatomical difficulties in accessing the right adrenal vein. We investigated whether C-arm computed tomography-assisted AVS (C-AVS) could improve the success rate of adrenal sampling. A total of 156 patients, diagnosed with PA who underwent AVS from May 2004 through April 2017, were included. Based on the medical records, we retrospectively compared the overall, left, and right catheterization success rates of adrenal veins during the periods without C-AVS (2004 to 2010, n=32) and with C-AVS (2011 to 2016, n=134). The primary outcome was adequate bilateral sampling defined as a selectivity index (SI) >5. With C-AVS, the rates of adequate bilateral AVS increased from 40.6% to 88.7% (PAVS was an independent predictor of adequate bilateral sampling in the multivariate model (odds ratio, 9.01; PAVS improved the overall success rate of AVS, possibly as a result of better catheterization of right adrenal vein. Copyright © 2018 Korean Endocrine Society.

Arabidopsis thaliana Ei-5: Minor Vein Architecture Adjustment Compensates for Low Vein Density in Support of Photosynthesis.

Science.gov (United States)

Stewart, Jared J; Polutchko, Stephanie K; Demmig-Adams, Barbara; Adams, William W

2018-01-01

An Arabidopsis thaliana accession with naturally low vein density, Eifel-5 (Ei-5), was compared to Columbia-0 (Col-0) with respect to rosette growth, foliar vein architecture, photosynthesis, and transpiration. In addition to having to a lower vein density, Ei-5 grew more slowly, with significantly lower rates of rosette expansion, but had similar capacities for photosynthetic oxygen evolution on a leaf area basis compared to Col-0. The individual foliar minor veins were larger in Ei-5, with a greater number of vascular cells per vein, compared to Col-0. This compensation for low vein density resulted in similar values for the product of vein density × phloem cell number per minor vein in Ei-5 and Col-0, which suggests a similar capacity for foliar sugar export to support similar photosynthetic capacities per unit leaf area. In contrast, the product of vein density × xylem cell number per minor vein was significantly greater in Ei-5 compared to Col-0, and was associated not only with a higher ratio of water-transporting tracheary elements versus sugar-transporting sieve elements but also significantly higher foliar transpiration rates per leaf area in Ei-5. In contrast, previous studies in other systems had reported higher ratios of tracheary to sieve elements and higher transpiration rate to be associated with higher - rather than lower - vein densities. The Ei-5 accession thus further underscores the plasticity of the foliar vasculature by illustrating an example where a higher ratio of tracheary to sieve elements is associated with a lower vein density. Establishment of the Ei-5 accession, with a low vein density but an apparent overcapacity for water flux through the foliar xylem network, may have been facilitated by a higher level of precipitation in its habitat of origin compared to that of the Col-0 accession.

A method of layer-by-layer gold nanoparticle hybridization in a quartz crystal microbalance DNA sensing system used to detect dengue virus

International Nuclear Information System (INIS)

Chen, S-H; Chuang, Y-C; Lu, Y-C; Lin, H-C; Yang, Y-L; Lin, C-S

2009-01-01

Dengue virus (DENV) is nowadays the most important arthropod-spread virus affecting humans existing in more than 100 countries worldwide. A rapid and sensitive detection method for the early diagnosis of infectious dengue virus urgently needs to be developed. In the present study, a circulating-flow quartz crystal microbalance (QCM) biosensing method combining oligonucleotide-functionalized gold nanoparticles (i.e. AuNP probes) used to detect DENV has been established. In the DNA-QCM method, two kinds of specific AuNP probes were linked by the target sequences onto the QCM chip to amplify the detection signal, i.e. oscillatory frequency change (ΔF) of the QCM sensor. The target sequences amplified from the DENV genome act as a bridge for the layer-by-layer AuNP probes' hybridization in the method. Besides being amplifiers of the detection signal, the specific AuNP probes used in the DNA-QCM method also play the role of verifiers to specifically recognize their target sequences in the detection. The effect of four AuNP sizes on the layer-by-layer hybridization has been evaluated and it is found that 13 nm AuNPs collocated with 13 nm AuNPs showed the best hybridization efficiency. According to the nanoparticle application, the DNA-QCM biosensing method was able to detect dengue viral RNA in virus-contaminated serum as plaque titers being 2 PFU ml -1 and a linear correlation (R 2 = 0.987) of ΔF versus virus titration from 2 x 10 0 to 2 x 10 6 PFU ml -1 was found. The sensitivity and specificity of the present DNA-QCM method with nanoparticle technology showed it to be comparable to the fluorescent real-time PCR methods. Moreover, the method described herein was shown to not require expensive equipment, was label-free and highly sensitive.

A method of layer-by-layer gold nanoparticle hybridization in a quartz crystal microbalance DNA sensing system used to detect dengue virus

Energy Technology Data Exchange (ETDEWEB)

Chen, S-H; Chuang, Y-C; Lu, Y-C; Lin, H-C; Yang, Y-L; Lin, C-S [Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30068, Taiwan (China)], E-mail: lincs@mail.nctu.edu.tw

2009-05-27

Dengue virus (DENV) is nowadays the most important arthropod-spread virus affecting humans existing in more than 100 countries worldwide. A rapid and sensitive detection method for the early diagnosis of infectious dengue virus urgently needs to be developed. In the present study, a circulating-flow quartz crystal microbalance (QCM) biosensing method combining oligonucleotide-functionalized gold nanoparticles (i.e. AuNP probes) used to detect DENV has been established. In the DNA-QCM method, two kinds of specific AuNP probes were linked by the target sequences onto the QCM chip to amplify the detection signal, i.e. oscillatory frequency change ({delta}F) of the QCM sensor. The target sequences amplified from the DENV genome act as a bridge for the layer-by-layer AuNP probes' hybridization in the method. Besides being amplifiers of the detection signal, the specific AuNP probes used in the DNA-QCM method also play the role of verifiers to specifically recognize their target sequences in the detection. The effect of four AuNP sizes on the layer-by-layer hybridization has been evaluated and it is found that 13 nm AuNPs collocated with 13 nm AuNPs showed the best hybridization efficiency. According to the nanoparticle application, the DNA-QCM biosensing method was able to detect dengue viral RNA in virus-contaminated serum as plaque titers being 2 PFU ml{sup -1} and a linear correlation (R{sup 2} = 0.987) of {delta}F versus virus titration from 2 x 10{sup 0} to 2 x 10{sup 6} PFU ml{sup -1} was found. The sensitivity and specificity of the present DNA-QCM method with nanoparticle technology showed it to be comparable to the fluorescent real-time PCR methods. Moreover, the method described herein was shown to not require expensive equipment, was label-free and highly sensitive.

MOUNT HOOD WILDERNESS AND ADJACENT AREAS, OREGON.

Science.gov (United States)

Keith, T.E.C.; Causey, J.D.

1984-01-01

A mineral survey of the Mount Hood Wilderness, Oregon, was conducted. Geochemical data indicate two areas of substantiated mineral-resource potential containing weak epithermal mineralization: an area of the north side of Zigzag Mountain where vein-type lead-zinc-silver deposits occur and an area of the south side of Zigzag Mountain, where the upper part of a quartz diorite pluton has propylitic alteration associated with mineralization of copper, gold, silver, lead, and zinc in discontinuous veins. Geothermal-resource potential for low- to intermediate-temperature (less than 248 degree F) hot-water systems in the wilderness is probable in these areas. Part of the wilderness is classified as a Known Geothermal Resource Area (KGRA), which is considered to have probable geothermal-resource potential, and two parts of the wilderness have been included in geothermal lease areas.

Role of Sulfur in the Formation of Magmatic-Hydrothermal Copper-Gold Deposits

Science.gov (United States)

Seo, J.; Guillong, M.; Heinrich, C.

2009-05-01

Sulfur plays essential roles in hydrothermal ore-forming processes [1], which calls for precise and accurate quantitative sulfur determination in fluid inclusions. Feasibility tests for sulfur quantification by comparing data from both LA-Quadrupole (Q) - ICP-MS and LA-High Resolution (HR) - ICP-MS show that reliable sulfur quantification in fluid inclusions is possible [2], provided that a very careful baseline correction is applied. We investigate the metal transporting capabilities of sulfur by measuring sulfur together with copper and other elements in cogenetic brine and vapor inclusions ('boiling assemblages') in single healed crack hosted by quartz veins. Samples are from high-temperature magmatic-hydrothermal ore deposits and miarolitic cavities of barren granitoid. Clear compositional correlations of sulfur with copper and gold were found. A molar S/Cu ratio commonly close to 2 but never above 2, indicates sulfur-complexed metal transportation in the high-temperature hydrothermal vapor, and probably also in the Na-Fe-K-Cl-enriched brines. Vapor/brine partitioning trends of the S and Cu are shown to be related with the chemistry of the fluids (possibly by various sulfur speciations in varying pH, fO2) and causative magma source. In the boiling hydrothermal environments, higher vapor partitioning of Cu and S is observed at reduced and peraluminous Sn-W granite, whereas oxidized and perakaline porphyry-style deposits have a lower partitioning to the vapor although the total concentration of S, Cu, Au in both fluid phase is higher than in the Sn-W granite [3]. Vapor inclusion in the boiling assemblages from magmatic-hydrothermal ore deposits and granitic intrusions generally contain an excess of sulfur over ore metals such as Cu, Fe, and Mo. This allows efficient sulfide ore precipitation in high-temperature porphyry-type deposits, and complexation of gold by the remaining sulfide down to lower temperatures. The results confirm earlier interpretations [1] and

Strata-bound Fe-Co-Cu-Au-Bi-Y-REE deposits of the Idaho Cobalt Belt: Multistage hydrothermal mineralization in a magmatic-related iron oxide copper-gold system

Science.gov (United States)

Slack, John F.

2012-01-01

Mineralogical and geochemical studies of strata-bound Fe-Co-Cu-Au-Bi-Y-rare-earth element (REE) deposits of the Idaho cobalt belt in east-central Idaho provide evidence of multistage epigenetic mineralization by magmatic-hydrothermal processes in an iron oxide copper-gold (IOCG) system. Deposits of the Idaho cobalt belt comprise three types: (1) strata-bound sulfide lenses in the Blackbird district, which are cobaltite and, less commonly, chalcopyrite rich with locally abundant gold, native bismuth, bismuthinite, xenotime, allanite, monazite, and the Be-rich silicate gadolinite-(Y), with sparse uraninite, stannite, and Bi tellurides, in a gangue of quartz, chlorite, biotite, muscovite, garnet, tourmaline, chloritoid, and/or siderite, with locally abundant fluorapatite or magnetite; (2) discordant tourmalinized breccias in the Blackbird district that in places have concentrations of cobaltite, chalcopyrite, gold, and xenotime; and (3) strata-bound magnetite-rich lenses in the Iron Creek area, which contain cobaltiferous pyrite and locally sparse chalcopyrite or xenotime. Most sulfide-rich deposits in the Blackbird district are enclosed by strata-bound lenses composed mainly of Cl-rich Fe biotite; some deposits have quartz-rich envelopes.Whole-rock analyses of 48 Co- and/or Cu-rich samples show high concentrations of Au (up to 26.8 ppm), Bi (up to 9.16 wt %), Y (up to 0.83 wt %), ∑REEs (up to 2.56 wt %), Ni (up to 6,780 ppm), and Be (up to 1,180 ppm), with locally elevated U (up to 124 ppm) and Sn (up to 133 ppm); Zn and Pb contents are uniformly low (≤821 and ≤61 ppm, respectively). Varimax factor analysis of bulk compositions of these samples reveals geochemically distinct element groupings that reflect statistical associations of monazite, allanite, and xenotime; biotite and gold; detrital minerals; chalcopyrite and sparse stannite; quartz; and cobaltite with sparse selenides and tellurides. Significantly, Cu is statistically separate from Co and As

Luminescence sensitivity changes in quartz

CERN Document Server

Wintle, A G

1999-01-01

In the luminescence dating of sedimentary or heated quartz, some heat treatment is usually applied to the sample immediately prior to the measurement of the optically stimulated luminescence. In this paper we report experiments on a 30,000-year-old sedimentary quartz, in which we use the luminescence response to a test dose to monitor the changes in sensitivity that are caused by holding the quartz at temperatures from 160 to 280 deg. C for times from 10 s to 22 h. For an optically bleached sample, the monitoring is by both optically stimulated luminescence and the 110 deg. C TL peak; both luminescence signals are shown to have the same sensitisation (i.e. activation energy) characteristics. For natural or laboratory irradiated samples only the 110 deg. C TL peak can be used; sensitivity increases of up to a factor of 1.3 and 3 are observed for the natural and laboratory irradiated aliquots, respectively. Up to four exponential components are used to deconvolve the sensitivity change data; the dominant compon...

Ligation of superior mesenteric vein and portal to splenic vein anastomosis after superior mesenteric-portal vein confluence resection during pancreaticoduodenectomy – Case report

Directory of Open Access Journals (Sweden)

Jianlin Tang

2014-12-01

Conclusion: The lessons we learned are (1 Before SMPV confluence resection, internal jugular vein graft should be ready for reconstruction. (2 Synthetic graft is an alternative for internal jugular vein graft. (3 Direct portal vein to SMV anastomosis can be achieved by mobilizing liver. (4 It is possible that venous collaterals secondary to SMV tumor obstruction may have allowed this patient's post-operative survival.

Vein visualization: patient characteristic factors and efficacy of a new infrared vein finder technology.

Science.gov (United States)

Chiao, F B; Resta-Flarer, F; Lesser, J; Ng, J; Ganz, A; Pino-Luey, D; Bennett, H; Perkins, C; Witek, B

2013-06-01

We investigated the patient characteristic factors that correlate with identification of i.v. cannulation sites with normal eyesight. We evaluated a new infrared vein finding (VF) technology device in identifying i.v. cannulation sites. Each subject underwent two observations: one using the conventional method (CM) of normal, unassisted eyesight and the other with the infrared VF device, VueTek's Veinsite™ (VF). A power analysis for moderate effect size (β=0.95) required 54 samples for within-subject differences. Patient characteristic profiles were obtained from 384 subjects (768 observations). Our sample population exhibited an overall average of 5.8 [95% confidence interval (CI) 5.4-6.2] veins using CM. As a whole, CM vein visualization were less effective among obese [4.5 (95% CI 3.8-5.3)], African-American [4.6 (95% CI 3.6-5.5 veins)], and Asian [5.1 (95% CI 4.1-6.0)] subjects. Next, the VF technology identified an average of 9.1 (95% CI 8.6-9.5) possible cannulation sites compared with CM [average of 5.8 (95% CI 5.4-6.2)]. Seventy-six obese subjects had an average of 4.5 (95% CI 3.8-5.3) and 8.2 (95% CI 7.4-9.1) veins viewable by CM and VF, respectively. In dark skin subjects, 9.1 (95% CI 8.3-9.9) veins were visible by VF compared with 5.4 (95% CI 4.8-6.0) with CM. African-American or Asian ethnicity, and obesity were associated with decreased vein visibility. The visibility of veins eligible for cannulation increased for all subgroups using a new infrared device.

Palliative treatment of TIPS to portal vein tumor thrombosis complicated with portal vein hypertension

International Nuclear Information System (INIS)

Jiang Zaibo; Shan Hong; Guan Shouhai; Zhu Kangshun; Huang Mingsheng; Li Zhengran; Guo Tiansheng; Liu Lang

2002-01-01

Objective: To evaluate the palliative therapeutic effects of transjugular intrahepatic portosystemic shunt (TIPS) in portal vein tumor thrombosis (PVTT) complicated with portal vein hypertension, and to discuss the technical skills. Methods: There were 14 cases of end-stage hepatocellular carcinoma complicated with PVTT and portal vein hypertension, the average age was 53.6 yr. There were 8 cases with complete occlusion of main portal vein, 6 eases with incomplete thrombosis, and 5 cases combined with portal vein cavernous transformation. One case had simple hemorrhage, 3 eases had intractable ascites, and 10 cases had hemorrhage accompanied by intractable ascites. Results: The procedure of TIPS was successful in 10 cases, the successful rate was about 71%. The mean portal vein pressure was reduced from 37.2 mm Hg to 18.2 mm Hg, with an average reduction of 19.0 mm Hg. After the procedure of TIPS, the ascites decreased, hemorrhage stopped and the clinical symptoms disappeared. The average survival period was 132.3 days. The procedure were failing in 4 cases. Conclusion: TIPS was an effective palliative therapeutic methods to control the hemorrhage and ascites aroused by hepatic carcinoma complicated with PVTT

External micro-PIXE analysis of fluid inclusions: Test of the LABEC facility on samples of quartz veins from Apuan Alps (Italy)

International Nuclear Information System (INIS)

Massi, M.; Calusi, S.; Giuntini, L.; Ruggieri, G.; Dini, A.

2008-01-01

Fluid inclusions are small portions, usually smaller than 100 μm, of fluid trapped within minerals during or after growth. Their characteristics provide therefore fundamental information on nature and evolution of fluids present in the past in different geological environments. At the LABEC laboratory in Firenze, high-salinity fluid inclusions in quartz crystals, coming from the Apuan Alps metamorphic complex, were analysed at the external scanning microbeam. Results, although still preliminary, have already provided us with hints on fluid-rock interaction processes during the metamorphism of the Apuan Alps

External micro-PIXE analysis of fluid inclusions: Test of the LABEC facility on samples of quartz veins from Apuan Alps (Italy)

Energy Technology Data Exchange (ETDEWEB)

Massi, M. [Dipartimento di Fisica dell' Universita and INFN sezione di Firenze, via G. Sansone 1, Sesto Fiorentino 50019, Firenze (Italy)], E-mail: massi@fi.infn.it; Calusi, S. [Dipartimento di Fisica dell' Universita and INFN sezione di Torino, via P. Giuria 1, 10125 Torino (Italy); Giuntini, L. [Dipartimento di Fisica dell' Universita and INFN sezione di Firenze, via G. Sansone 1, Sesto Fiorentino 50019, Firenze (Italy); Ruggieri, G. [CNR - Istituto di Geoscienze e Georisorse sezione di Firenze, via G. La Pira 4, Firenze 50121 (Italy); Dini, A. [CNR - Istituto di Geoscienze e Georisorse sezione di Pisa, via G. Moruzzi 1, Pisa 56124 (Italy)

2008-05-15

Fluid inclusions are small portions, usually smaller than 100 {mu}m, of fluid trapped within minerals during or after growth. Their characteristics provide therefore fundamental information on nature and evolution of fluids present in the past in different geological environments. At the LABEC laboratory in Firenze, high-salinity fluid inclusions in quartz crystals, coming from the Apuan Alps metamorphic complex, were analysed at the external scanning microbeam. Results, although still preliminary, have already provided us with hints on fluid-rock interaction processes during the metamorphism of the Apuan Alps.

Microbially induced separation of quartz from hematite using sulfate reducing bacteria.

Science.gov (United States)

Prakasan, M R Sabari; Natarajan, K A

2010-07-01

Cells and metabolic products of Desulfovibrio desulfuricans were successfully used to separate quartz from hematite through environmentally benign microbially induced flotation. Bacterial metabolic products such as extracellular proteins and polysaccharides were isolated from both unadapted and mineral-adapted bacterial metabolite and their basic characteristics were studied in order to get insight into the changes brought about on bioreagents during adaptation. Interaction between bacterial cells and metabolites with minerals like hematite and quartz brought about significant surface-chemical changes on both the minerals. Quartz was rendered more hydrophobic, while hematite became more hydrophilic after biotreatment. The predominance of bacterial polysaccharides on interacted hematite and of proteins on quartz was responsible for the above surface-chemical changes, as attested through adsorption studies. Surface-chemical changes were also observed on bacterial cells after adaptation to the above minerals. Selective separation of quartz from hematite was achieved through interaction with quartz-adapted bacterial cells and metabolite. Mineral-specific proteins secreted by quartz-adapted cells were responsible for conferment of hydrophobicity on quartz resulting in enhanced separation from hematite through flotation. 2010 Elsevier B.V. All rights reserved.

Thermal quenching of thermoluminescence in quartz samples of various origin

International Nuclear Information System (INIS)

Subedi, B.; Oniya, E.; Polymeris, G.S.; Afouxenidis, D.; Tsirliganis, N.C.; Kitis, G.

2011-01-01

The effect of thermal quenching stands among the most important properties in the thermoluminescence (TL) of quartz on which many applications of TL are based. Since the quartz samples used in various applications are all of different origin it is useful to investigate whether the values of the thermal quenching parameters, i.e. the activation energy for thermal quenching W and a parameter C which describes the ratio of non-radiative to radiative luminescence transitions, evaluated mainly in specific quartz samples can be extrapolated to quartz samples of unknown origin as well as to quartz samples which are annealed at high temperatures. In the present work the TL glow curve of a series of un-annealed and annealed natural and synthetic quartz samples were studied as a function of the heating rate between 0.25 K/s and 16 K/s. Using an indirect fitting method it was found that the thermal quenching parameters W and C in most of the quartz samples are very similar to the values accepted in the literature. Furthermore, in some cases the thermal quenching parameters W and C are not the same for all TL glow-peaks in the same glow-curve. Finally, the strong external treatment of annealing the quartz samples at very high temperature can also influence at least one of the thermal quenching parameters.

Concerns and Discomforts of Pregnancy - Varicose Veins

Science.gov (United States)

Concerns and Discomforts of Pregnancy - Varicose Veins Varicose veins are enlarged veins you may see on your ... Healthy Roads Media project www. healthyroadsmedia. org English - Concerns and Discomforts of Pregnancy (Varicose Veins) Last reviewed ...

Quartz exsolution topotaxy in clinopyroxene from the UHP eclogite of Weihai, China

Science.gov (United States)

Xu, Haijun; Zhang, Junfeng; Zong, Keqing; Liu, Liang

2015-06-01

Abundant oriented silica precipitates of α-quartz (4.0 ± 1.0 vol.%), in part coexisting with calcic amphiboles (topotactic relationships with their host clinopyroxenes. Three types of crystallographic topotactic relationship have been identified between quartz and host clinopyroxene: (1) 52% quartz precipitates share the same orientation for the c-axes with [0001]qz//[001]cpx; (2) 34% quartz precipitates share the same orientation for the a-axes with [11 2 bar0]qz//[001]cpx; and (3) 11% quartz precipitates share the same orientation for the s-planes with (11 2 bar1)qz//(100)cpx. Other quartz axes and planes disperse in large or small girdles around the shared axes or planes. Many quartz rods/needles are elongated parallel to the [001]cpx with the long axes of quartz being either [0001]qz or [11 2 bar0]qz. Amphibole precipitates have also a strong crystallographic relationship with host clinopyroxene, i.e., (100)amp//(100)cpx, [010]amp//[010]cpx, and [001]amp//[001]cpx. These results provide quantitative microstructural evidence supporting an exsolution origin for oriented quartz needles/rods in clinopyroxene and demonstrate that the exsolution of quartz from clinopyroxene occurred within the stability field of α-quartz rather than coesite. The oriented precipitates of α-quartz, in part coexisting with calcic amphiboles, in host clinopyroxene are probably promoted by supercritical fluid or partial melting during the early exhumation of eclogites. Our results suggest that oriented quartz precipitates in clinopyroxene cannot be used as an indisputable UHP-indicator.

Corrosion cast study of the canine hepatic veins.

Science.gov (United States)

Uršič, M; Vrecl, M; Fazarinc, G

2014-11-01

This study presents a detailed description of the distribution, diameters and drainage patterns of hepatic veins on the basis of the corrosion cast analysis in 18 dogs. We classified the hepatic veins in three main groups: the right hepatic veins of the caudate process and right lateral liver lobe, the middle hepatic veins of the right medial and quadrate lobes and the left hepatic veins of both left liver lobes and the papillary process. The corrosion cast study showed that the number of the veins in the Nomina Anatomica Veterinaria and most anatomical textbooks is underestimated. The number of various-sized hepatic veins of the right liver division ranged from 3 to 5 and included 1 to 4 veins from the caudate process and 2 to 4 veins from the right lateral liver lobe. Generally, in all corrosion casts, one middle-sized vein from the right part of the right medial lobe, which emptied separately in the caudal vena cava, was established. The other vein was a large-sized vein from the remainder of the central division, which frequently joined the common left hepatic vein from the left liver lobes. The common left hepatic vein was the largest of all the aforementioned hepatic veins.

Image Quality Enhancement Using the Direction and Thickness of Vein Lines for Finger-Vein Recognition

Directory of Open Access Journals (Sweden)

Young Ho Park

2012-10-01

Full Text Available On the basis of the increased emphasis placed on the protection of privacy, biometric recognition systems using physical or behavioural characteristics such as fingerprints, facial characteristics, iris and finger-vein patterns or the voice have been introduced in applications including door access control, personal certification, Internet banking and ATM machines. Among these, finger-vein recognition is advantageous in that it involves the use of inexpensive and small devices that are difficult to counterfeit. In general, finger-vein recognition systems capture images by using near infrared (NIR illumination in conjunction with a camera. However, such systems can face operational difficulties, since the scattering of light from the skin can make capturing a clear image difficult. To solve this problem, we proposed new image quality enhancement method that measures the direction and thickness of vein lines. This effort represents novel research in four respects. First, since vein lines are detected in input images based on eight directional profiles of a grey image instead of binarized images, the detection error owing to the non-uniform illumination of the finger area can be reduced. Second, our method adaptively determines a Gabor filter for the optimal direction and width on the basis of the estimated direction and thickness of a detected vein line. Third, by applying this optimized Gabor filter, a clear vein image can be obtained. Finally, the further processing of the morphological operation is applied in the Gabor filtered image and the resulting image is combined with the original one, through which finger-vein image of a higher quality is obtained. Experimental results from application of our proposed image enhancement method show that the equal error rate (EER of finger-vein recognition decreases to approximately 0.4% in the case of a local binary pattern-based recognition and to approximately 0.3% in the case of a wavelet transform

Study of green quartz of hydrothermal origin treated by gamma radiation; Estudo do quartzo verde de origem hidrotermal tratado com radiacao gama

Energy Technology Data Exchange (ETDEWEB)

Enokihara, Cyro Teiti

2013-07-01

) compared with heating techniques (3200 ppm), probably due to remaining silanol complexes.To trace the influence of water on color formation, samples from 3 different geological settings (high temperature pegmatitic quartz with Al and Li, from Santana de Araguaia; intermediate temperature vein quartz with Al but without water from Curvelo; amethyst with more Fe, less Al and small silanol content from Brejinho, and low temperature regimes from geodes, high silanol and high molecular water, cations similar to the above mentioned) have been analyzed by NIR spectroscopy.The former will not show green color, only the latter one. It may be mentioned that even in geodes one has crystals with high and intermediate water content coexisting. The crystals with high silanol and molecular water are the ones to treat by radiation. The radiation induced color is heat and UV sensible with bleaching by longer exposure to these factors. (author)

Normal hepatic vein patterns on ultrasound

International Nuclear Information System (INIS)

Kim, Hae Jin; Chae, Yoo Soon; Park, Hea Yeoung; Park, Bok Hwan; Kim, Yang Sook

1987-01-01

Understanding of the anatomy of the hepatic vein is important in manipulation for transplantation of the liver, hepatectomy and the treatment of hepatic trauma with avulsion of the hepatic vein. Demonstrated of the inferior right hepatic vein (IRHV) is also important; in some cases of hepatocellular carcinoma, thrombus can be seen in the IRHV; in primary Budd-Chiari syndrome, the IRHV is main draining vein; during hepatectomy, the postero-inferior segment of the right lobe and draining IRHV can be preserved. For some 10 months ultrasound examination was done in a total of 124 patients with normal liver function with special emphasis on the hepatic vein, their branches, and the IRHV, and analysed in terms of branching pattern and relative size of the hepatic vein and the detection rate of the IRHV.

Passivation of quartz for halogen-containing light sources

Science.gov (United States)

Falkenstein, Zoran

1999-01-01

Lifetime of halogen containing VUV, UV, visible or IR light sources can be extended by passivating the quartz or glass gas containers with halogens prior to filling the quartz with the halogen and rare gas mixtures used to produce the light.

Sectional localization of a small hepatocellular carcinoma in the right hepatic lobe by computed tomography: Comparison between the conventional and portal vein tracing methods

Energy Technology Data Exchange (ETDEWEB)

Zhou, Chun-Gao [Seoul National University Hospital, Department of Radiology, Jongro-gu, Seoul (Korea, Republic of); The First Affiliated Hospital of Nanjing Medical University, Department of Interventional Radiology, Nanjing (China); Chung, Jin Wook; Hur, Saebeom; Lee, Myungsu; Kim, Hyo-Cheol; Jae, Hwan Jun; Yin, Yong-Hu; Kim, Young Il [Seoul National University Hospital, Department of Radiology, Jongro-gu, Seoul (Korea, Republic of); Ahn, Sang-bu [Dongnam Institution of Radiological and Medical Sciences, Department of Radiology, Busan (Korea, Republic of); Cho, Baik Hwan [Chonbuk National University Hospital, Department of Radiology, Jeonju (Korea, Republic of)

2016-12-15

To compare the accuracy of the conventional and portal vein tracing methods in the right hepatic lobe in multidetector computed tomography (MDCT). This retrospective study included patients with hepatocellular carcinoma (HCC) lesions in the right hepatic lobe who underwent multiphasic MDCT and C-arm CT hepatic arteriography (C-arm CTHA) for chemoembolization. The accuracies of the conventional and portal vein tracing methods were evaluated using C-arm CTHA as the gold standard. A total of 147 patients with 205 HCC nodules were included. The C-arm CTHA could identify all the tumour-feeding arteries and consequently demonstrated that 120 lesions were located in the anterior section, 78 in the posterior section, and 7 in the border zone. The accuracy rates of conventional vs. portal vein tracing methods were 71.7 % vs. 98.3 % for the anterior section lesions, 67.9 % vs. 96.2 % for the posterior section, and 28.6 % vs. 57.1 % for the border zone. The portal vein tracing method was more accurate than the conventional method (P<0.001). The portal vein tracing method should be used for sectional localization of HCCs in the right lobe, because it predicts the location more accurately than the conventional method. (orig.)

The umbilical and paraumbilical veins of man.

Science.gov (United States)

Martin, B F; Tudor, R G

1980-03-01

During its transit through the umbilicus structural changes occur in the thick wall of the extra-abdominal segment of the umbilical vein whereby the components of the intra-abdominal segment acquire an essentially longitudinal direction and become arranged in fibro-elastic and fibro-muscular zones. The vein lumen becomes largely obliterated by asymmetrical proliferation of loose subendothelial conective tissue. The latter forms a new inner zone within which a small segment of the lumen persists in an eccentric position. This residual lumen transmits blood to the portal system from paraumbilical and systemic sources, and is retained in the upper part of the vein, even in old age. A similar process of lumen closure is observed in the ductus venosus. In early childhood the lower third of the vein undergoes breakdown, with fatty infiltration, resulting in its complete division into vascular fibro-elastic strands, and in old age some breakdown occurs in the outermost part of the wall of the upper two thirds. The paraumbilical veins are thick-walled and of similar structure to the umbilical vein. Together they constitute an accessory portal system which is confined between the layers of the falciform ligament and is in communication with the veins of the ventral abdominal wall. The constituents form an ascending series, namely, Burow's veins, the umbilical vein, and Sappey's inferior and superior veins. The main channel of Sappey's inferior veins may be the remnant of the right umbilical vein since it communicates with the right rectus sheath and often communicates directly with the portal system within the right lobe of the liver. The results are of significance in relation to clinical usage of the umbilical vein.

Idiopathic Bilateral External Jugular Vein Thrombosis.

Science.gov (United States)

Hindi, Zakaria; Fadhel, Ehab

2015-08-20

Vein thrombosis is mainly determined by 3 factors, which constitute a triad called Virchow's triad: hypercoagulability, stasis, and endothelial injury. Venous thrombosis commonly occurs in the lower extremities since most of the blood resides there and flows against gravity. The veins of the lower extremities are dependent on intact valves and fully functional leg muscles. However, in case of valvular incompetency or muscular weakness, thrombosis and blood stasis will occur as a result. In contrast, the veins of the neck, specially the jugulars, have distensible walls which allow flexibility during respiration. In addition, the blood directly flows downward towards the heart. Nevertheless, many case reports mentioned the thrombosis of internal jugular veins and external jugular veins with identified risk factors. Jugular vein thrombosis has previously been associated in the literature with a variety of medical conditions, including malignancy. This report is of a case of idiopathic bilateral external jugular vein thrombosis in a 21 year-old male construction worker of Southeast Asian origin with no previous medical history who presented with bilateral facial puffiness of gradual onset over 1 month. Doppler ultrasound and computed tomography were used in the diagnosis. Further work-up showed no evidence of infection or neoplasia. The patient was eventually discharged on warfarin. The patient was assessed after 6 months and his symptoms had resolved completely. Bilateral idiopathic external jugular veins thrombosis is extremely rare and can be an indicator of early malignancy or hidden infection. While previous reports in the literature have associated jugular vein thrombosis with malignancy, the present case shows that external jugular vein thrombosis can also be found in persons without malignancy.

Mineralogical, stable isotope, and fluid inclusion studies of spatially related porphyry Cu and epithermal Au-Te mineralization, Fakos Peninsula, Limnos Island, Greece

Science.gov (United States)

Fornadel, Andrew P.; Voudouris, Panagiotis Ch.; Spry, Paul G.; Melfos, Vasilios

2012-05-01

of magmatic fluids with meteoric water in the epithermal environment is responsible for the dilution of the ore fluids that formed Stage 3 veins. Eutectic melting temperatures of -35.4 to -24.3 °C for Type I inclusions hosted in both porphyry- and epithermal-style veins suggest the presence of CaCl2, MgCl2, and/or FeCl2 in the magmatic-hydrothermal fluids. Sulfur isotope values of pyrite, galena, sphalerite, and molybdenite range from δ34S = -6.82 to -0.82 per mil and overlap for porphyry and epithermal sulfides, which suggests a common sulfur source for the two styles of mineralization. The source of sulfur in the system was likely the Fakos quartz monzonite for which the isotopically light sulfur isotope values are the result of changes in oxidation state during sulfide deposition (i.e., boiling) and/or disproportionation of sulfur-rich magmatic volatiles upon cooling. It is less likely that sulfur in the sulfides was derived from the reduction of seawater sulfate or leaching of sulfides from sedimentary rocks given the absence of primary sulfides in sedimentary rocks in the vicinity of the deposit. Late-stage barite (δ34S = 10.5 per mil) is inferred to have formed during mixing of seawater with magmatic ore fluids. Petrological, mineralogical, fluid inclusion, and sulfur isotope data indicate that the metallic mineralization at Fakos Peninsula represents an early porphyry system that is transitional to a later high- to intermediate-sulfidation epithermal gold system. This style of mineralization is similar to porphyry-epithermal metallic mineralization found elsewhere in northeastern Greece (e.g., Pagoni Rachi, St. Demetrios, St. Barbara, Perama Hill, Mavrokoryfi, and Pefka).

Blood sampling from adrenal gland vein

International Nuclear Information System (INIS)

Sun Yong; Ni Caifang

2009-01-01

Adrenal gland vein sampling is an interventional method to get the blood samples from the adrenal gland vein. The blood is obtained via a catheter which is selectively inserted in the adrenal gland vein. This technique is mainly used to be diagnostic for primary hyperaldosteronism. A full knowledge of the anatomy and variations of the adrenal gland vein, serious preoperative preparation and skilled catheterization manipulation are necessary for obtaining sufficient blood sample and for reducing the occurrence of complications. Providing the physicians with definite diagnostic evidence and being technically feasible, adrenal gland vein sampling should become one of the routine examinations for clarifying the cause of primary hyperaldosteronism. (authors)

Fluid inclusion characteristics and geological significance of the Dajinshan W-Sn polymetallic deposit in Yunfu, Guangdong Province

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Yu, Zhangfa; Chen, Maohong; Zhao, Haijie

2015-05-01

The Dajinshan tungsten-tin polymetallic deposit is a quartz-vein-type ore deposit located in Western Guangdong Province. The ore bodies show a fairly simple shape and mainly occur as tungsten-tin polymetallic-bearing sulfide quartz veins, including quartz vein, quartz-greisens, and sulfide quartz veins, and their distribution is spatially related to Dajinshan granitoids. The formation of the deposit experienced three stages: a wolframite-molybdenite-quartz stage, a wolframite-cassiterite-sulfide-quartz stage, and a fluorite-calcite-carbonate stage. Based on detailed petrographic observations, we conducted microthermometric and Raman microspectroscopic studies of fluid inclusions formed at different ore-forming stages in the Dajinshan tungsten-tin polymetallic deposit, identifying four dominant types of fluid inclusions: aqueous two-phase inclusions, CO2-bearing inclusions, solid or daughter mineral-bearing inclusions, and gas-rich inclusions. The gas compositions of ore-forming fluids in the Dajinshan tungsten-tin polymetallic deposit are mostly CO2, CH4, and H2O. The hydrogen, oxygen, and sulfur isotopic data imply that the ore-forming fluids in the Dajinshan tungsten-tin polymetallic deposit were mainly derived from magmatic fluids, mixed with meteoric water in the ore-formation process. These results indicate that the fluid mixing and boiling led to the decomposition of the metal complex in ore-forming fluids and ore deposition.

Isolated inferior mesenteric portal hypertension with giant inferior mesenteric vein and anomalous inferior mesenteric vein insertion

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G Raghavendra Prasad

2013-01-01

Full Text Available Extrahepatic portal hypertension is not an uncommon disease in childhood, but isolated inferior mesenteric portal varices and lower gastrointestinal (GI bleed have not been reported till date. A 4-year-old girl presented with lower GI bleed. Surgical exploration revealed extrahepatic portal vein obstruction with giant inferior mesenteric vein and colonic varices. Inferior mesenteric vein was joining the superior mesenteric vein. The child was treated successfully with inferior mesenteric - inferior vena caval anastomosis. The child was relieved of GI bleed during the follow-up.

Multimodal ultrasonographic assessment of leiomyosarcoma of the femoral vein in a patient misdiagnosed as having deep vein thrombosis

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Zhang, Mei; Yan, Feng; Huang, Bin; Wu, Zhoupeng; Wen, Xiaorong

2017-01-01

Abstract Rationale: Primary leiomyosarcoma (LMS) of the vein is a rare tumor that arises from the smooth muscle cells of the vessel wall and has an extremely poor prognosis. This tumor can occur in vessels such as the inferior vena cava, great saphenous vein, femoral vein, iliac vein, popliteal vein, and renal vein; the inferior vena cava is the most common site. LMS of the femoral vein can result in edema and pain in the lower extremity; therefore, it is not easy to be differentiated from deep vein thrombosis (DVT). Moreover, virtually no studies have described the ultrasonographic features of LMS of the vein in detail. Patient concerns: We present a case of a 55-year-old woman with LMS of the left femoral vein that was misdiagnosed as having deep vein thrombosis (DVT) on initial ultrasonographic examination. The patient began to experience edema and pain in her left leg seven months previously. She was diagnosed as having DVT on initial ultrasonographic examination, but the DVT treatment that she had received for 7 months failed to improve the status of her left lower limb. Diagnoses: She subsequently underwent re-examination by means of a multimodal ultrasonographic imaging approach (regular B-mode imaging, color Doppler imaging, pulsed-wave Doppler imaging, contrast-enhanced ultrasonography), which confirmed a diagnosis of LMS. Interventions: This patient was treated successfully with surgery. Outcomes: This case demonstrates that use of multiple ultrasonographic imaging techniques can be helpful to diagnose LMS accurately. Detection of vasculature in a dilated vein filled with a heterogeneous hypoechoic substance on ultrasonography is a sign of a tumor. Lessons: The pitfall of misdiagnosing this tumor as DVT is a useful reminder. PMID:29145269

Duplex sonography of the near-surface leg veins

International Nuclear Information System (INIS)

Mendoza, E.

2007-01-01

The book contains the following contributions: The ultrasonograph, selection of the ultrasonic transducer, anatomy of the near-surface vein system, physiology of the near-surface vein system, varicose status classification, systematics of the duplex sonography of near-surface leg veins, provocational maneuver for the duplex sonographic varicose diagnostics, exploration of vena saphena parva, perforans veins, side branches, phlebitis, sonography for varicose therapy, postsurgical sonography, deep leg veins, examination of near-surface leg veins for the pathology of the deep vein system, differential diagnostic clarification of leg oedema from the phlebologic-lymphological view, diagnostic side features along the near-surface leg veins

Self-taught axillary vein access without venography for pacemaker implantation: prospective randomized comparison with the cephalic vein access.

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Squara, Fabien; Tomi, Julien; Scarlatti, Didier; Theodore, Guillaume; Moceri, Pamela; Ferrari, Emile

2017-12-01

Axillary vein access for pacemaker implantation is uncommon in many centres because of the lack of training in this technique. We assessed whether the introduction of the axillary vein technique was safe and efficient as compared with cephalic vein access, in a centre where no operators had any previous experience in axillary vein puncture. Patients undergoing pacemaker implantation were randomized to axillary or cephalic vein access. All three operators had no experience nor training in axillary vein puncture, and self-learned the technique by reading a published review. Axillary vein puncture was fluoroscopy-guided without contrast venography. Cephalic access was performed by dissection of delto-pectoral groove. Venous access success, venous access duration (from skin incision to guidewire or lead in superior vena cava), procedure duration, X-ray exposure, and peri-procedural (1 month) complications were recorded. results We randomized 74 consecutive patients to axillary (n = 37) or cephalic vein access (n = 37). Axillary vein was successfully accessed in 30/37 (81.1%) patients vs. 28/37 (75.7%) of cephalic veins (P = 0.57). Venous access time was shorter in axillary group than in cephalic group [5.7 (4.4-8.3) vs. 12.2 (10.5-14.8) min, P < 0.001], as well as procedure duration [34.8 (30.6-38.4) vs. 42.0 (39.1-46.6) min, P = 0.043]. X-ray exposure and peri-procedural overall complications were comparable in both groups. Axillary puncture was safe and faster than cephalic access even for the five first procedures performed by each operator. Self-taught axillary vein puncture for pacemaker implantation seems immediately safe and faster than cephalic vein access, when performed by electrophysiologists trained to pacemaker implantation but not to axillary vein puncture. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For Permissions, please email: journals.permissions@oup.com.

An Early Permian epithermal gold system in the Tulasu Basin in North Xinjiang, NW China: Constraints from in situ oxygen-sulfur isotopes and geochronology

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Dong, Leilei; Wan, Bo; Deng, Chen; Cai, Keda; Xiao, Wenjiao

2018-03-01

The Axi and Jingxi-Yelmand gold deposits, being the largest gold deposits in the Chinese North Tianshan, NW China, are located ca. l0 km apart in the Tulasu Basin, and are hosted by the Late Devonian - Early Carboniferous Dahalajunshan Formation. In situ LA-ICP-MS titanium analyses on quartz from the Axi and Jingxi-Yelmand deposits are broadly identical. Accordingly, the calculated ore-forming temperatures by Ti-in-quartz thermometer give average temperatures of 279 °C and 294 °C, respectively. Results of in situ SIMS analyses of oxygen and sulfur isotopes on quartz and pyrite from these two deposits are similar. Temperature-corrected fluids of the Axi deposit have δ18O values of 2.6-8.1‰ and δ34S values of 0.8-2.4‰, whereas the fluids of the Jingxi-Yelmand deposit have δ18O of 6.4-8.9‰ and δ34S of -0.4 to 4.0‰. The oxygen and sulfur isotopes from the two deposits indicate a magmatic origin. LA-ICP-MS zircon U-Pb ages of Aqialehe Formation sandstone provided a lower limit for the mineralization timing of the Axi deposit (288 Ma). In situ SIMS U-Pb analyses on entrapped zircon (297 Ma) and newly recognized 284.5 Ma columnar rhyolite implies that the Jingxi-Yelmand deposit formed in the Early Permian. Based on the magmatic affinity of the ore fluids, similar age and ore-formation temperatures, we propose that the Axi and Jingxi-Yelmand deposits comprise an epithermal gold system, which was driven by the same Permian magma in the Tulasu Basin. The ore geological features together with our new results indicate that the Axi and Jingxi-Yelmand deposits are intermediate and high sulfidation type epithermal deposits, respectively.

Portal vein thrombosis.

Science.gov (United States)

Chawla, Yogesh K; Bodh, Vijay

2015-03-01

Portal vein thrombosis is an important cause of portal hypertension. PVT occurs in association with cirrhosis or as a result of malignant invasion by hepatocellular carcinoma or even in the absence of associated liver disease. With the current research into its genesis, majority now have an underlying prothrombotic state detectable. Endothelial activation and stagnant portal blood flow also contribute to formation of the thrombus. Acute non-cirrhotic PVT, chronic PVT (EHPVO), and portal vein thrombosis in cirrhosis are the three main variants of portal vein thrombosis with varying etiological factors and variability in presentation and management. Procoagulant state should be actively investigated. Anticoagulation is the mainstay of therapy for acute non-cirrhotic PVT, with supporting evidence for its use in cirrhotic population as well. Chronic PVT (EHPVO) on the other hand requires the management of portal hypertension as such and with role for anticoagulation in the setting of underlying prothrombotic state, however data is awaited in those with no underlying prothrombotic states. TIPS and liver transplant may be feasible even in the setting of PVT however proper selection of candidates and type of surgery is warranted. Thrombolysis and thrombectomy have some role. TARE is a new modality for management of HCC with portal vein invasion.

Quartz enhanced photoacoustic spectroscopy based trace gas sensors using different quartz tuning forks.

Science.gov (United States)

Ma, Yufei; Yu, Guang; Zhang, Jingbo; Yu, Xin; Sun, Rui; Tittel, Frank K

2015-03-27

A sensitive trace gas sensor platform based on quartz-enhanced photoacoustic spectroscopy (QEPAS) is reported. A 1.395 μm continuous wave (CW), distributed feedback pigtailed diode laser was used as the excitation source and H2O was selected as the target analyte. Two kinds of quartz tuning forks (QTFs) with a resonant frequency (f0) of 30.72 kHz and 38 kHz were employed for the first time as an acoustic wave transducer, respectively for QEPAS instead of a standard QTF with a f0 of 32.768 kHz. The QEPAS sensor performance using the three different QTFs was experimentally investigated and theoretically analyzed. A minimum detection limit of 5.9 ppmv and 4.3 ppmv was achieved for f0 of 32.768 kHz and 30.72 kHz, respectively.

Quartz Enhanced Photoacoustic Spectroscopy Based Trace Gas Sensors Using Different Quartz Tuning Forks

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Yufei Ma

2015-03-01

Full Text Available A sensitive trace gas sensor platform based on quartz-enhanced photoacoustic spectroscopy (QEPAS is reported. A 1.395 μm continuous wave (CW, distributed feedback pigtailed diode laser was used as the excitation source and H2O was selected as the target analyte. Two kinds of quartz tuning forks (QTFs with a resonant frequency (f0 of 30.72 kHz and 38 kHz were employed for the first time as an acoustic wave transducer, respectively for QEPAS instead of a standard QTF with a f0 of 32.768 kHz. The QEPAS sensor performance using the three different QTFs was experimentally investigated and theoretically analyzed. A minimum detection limit of 5.9 ppmv and 4.3 ppmv was achieved for f0 of 32.768 kHz and 30.72 kHz, respectively.

Synthesis of gold and silver nanoparticles by electron irradiation at 5-15 keV energy

Energy Technology Data Exchange (ETDEWEB)

Mahapatra, S K; Bogle, K A; Dhole, S D; Bhoraskar, V N [Microtron Accelerator Laboratory, Department of Physics, University of Pune, Pune-411007 (India)

2007-04-04

Thin coatings ({approx}10 {mu}m) made from a mixture of polyvinyl alcohol (PVA) and HAuCl{sub 4} or PVA and AgNO{sub 3} on quartz plates were irradiated with 5-15 keV electrons, at room temperature. The electron energy was varied from coating to coating in the range of 5-15 keV, but electron fluence was kept constant at {approx}10{sup 15} e cm{sup -2}. Samples were characterized by the UV-vis, XRD, SEM and TEM techniques. The plasmon absorption peaks at {approx}511 and {approx}442 nm confirmed the formation of gold and silver nanoparticles in the respective electron-irradiated coatings. The XRD, SEM and TEM measurements reveal that the average size of the particles could be tailored in the range of 130-50 nm for gold and from 150-40 nm for silver by varying the electron energy in the range of 5-15 keV. These particles of gold and silver embedded in the polymer could also be separated by dissolving the coatings in distilled water.

Mineralogy of the Chaparra IOCG deposit, southern Peru

Science.gov (United States)

Yáñez, Juan; Alfonso, Pura

2014-05-01

The Chaparra IOCG, located in southern Peru, near Chala, is mined and exploited by small-scale miners for gold, however, it has not been studied until now. Here we present a preliminary geological and mineralogic study of this deposit. Powder X ray diffraction, electron microscopy and electron microprobe were used to characterize the mineralization. This deposit is hosted in magmatic rocks from the Coastal Batholith. Host rocks belong to the Linga Super-unit, of Upper Cretaceous age and are mainly constituted by monzonites, monzogabbros and diorites. Major alterations are the propylitic (chlorite - albite - quartz), advanced argillic (jarosite - natrojarosite) and sericitic (muscovite-sericite-quartz). Gypsum and other alteration minerals such as potassium feldspar and phlogopite, vermiculite and natrolite are widespread. Mineralization occurs mainly in quartz veins up to 1 m thick, emplaced filling fractures. Ore mineralogy is mainly composed of hematite, goethite, and sulphides (mainly pyrite, chalcopyrite and covellite). Gold and REE-rich minerals also occur. Native gold can reach up to 1 mm in size, but usually is few μm in size. Its composition is 82-92 wt% Au, up to 12 wt% of Ag and Fe can reach up to 4 wt%. The paragenetic sequence in the Chaparra deposit was divided into three stages: (I) primary mineralization, (II) Fracture filling, and (III) supergene alteration. The sequence begins with the crystallization of magnetite, quartz, pyrrhotite and pyrite. Subsequently, native gold, native Bismuth and uraninite crystallices together with the former minerals, in which are enclosed. Later, monacite is formed, being enclosed in quartz. Pyrite also presents small grains of chalcopyrite inside. Galena, sphalerite and arsenopyrite also are formed, whether included in pyrite or outside. Scarce grains of sakuraiite also occur in this stage. Structural formula of sakuraiie from this deposit is Cu 01.78-1.90 Zn 0.07-12Fe 1.16-124In 0.22-0.26Sn 0.79-082S4). Indium

Case report: Varicosity of the communicating vein between the left renal vein and the left ascending lumbar vein mimicking a renal artery aneurysm: Report of an unusual site of varicose veins and a novel hypothesis to explain its association with abdominal pain

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Sandeep G Jakhere

2011-01-01

Full Text Available A communicating vein between the left renal vein and the left ascending lumbar vein has only rarely been reported in the imaging literature. There are very few reports of varicosity of this communicating vein. Nonetheless, awareness about this communicating vein is of utmost importance for surgeons performing aortoiliac surgeries and nephrectomies as it may pose technical difficulties during surgery or cause life-threatening retroperitoneal hemorrhage. Varicosity of this venous channel may be mistaken for paraaortic lymphadenopathy, adrenal pseudo-mass, or renal artery aneurysm. We report a case of a patient with varicosity of this communicating vein, which mimicked a left renal artery aneurysm. A novel hypothesis is also proposed to explain the relationship with abdominal pain.

Estimating Quartz Reserves Using Compositional Kriging

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J. Taboada

2013-01-01

Full Text Available The aim of this study was to determine spatial distribution and volume of four commercial quartz grades, namely, silicon metal, ferrosilicon, aggregate, and kaolin (depending on content in impurities in a quartz seam. The chemical and mineralogical composition of the reserves in the seam were determined from samples collected from outcrops, blasting operations, and exploratory drilling, and compositional kriging was used to calculate the volume and distribution of the reserves. A more accurate knowledge of the deposit ensures better mine planning, leading to higher profitability and an improved relationship with the environment.

Interventional treatment of iliac vein compression syndrome

International Nuclear Information System (INIS)

Li Xiaoqiang; Zhou Weiming; Nie Zhonglin; Yu Chaowen

2002-01-01

Objective: To explore the clinical significance of interventional treatment of iliac vein compression syndrome (IVCS). Methods: Percutaneous transluminal angioplasty (PTA) was performed in 40 cases. Thirty-three cases underwent endovascular stent implantation and 27 cases underwent second-stage left saphenous vein ligation and stripping and the valves of left femoral veins narrowing. Thirty-one cases were followed-up postoperatively and the duration was 6-66 months (mean 28 months). Results: The dilation of iliac veins was successful in 36 cases and there were god efficacy in all patients when they discharged from hospital. Followed-up during post-operation, all the limbs ulcers were cured and varicose veins disappeared. The skin pigmentation disappeared in 17 of 19 cases and markedly relieved in 2 cases. Left lower limb swelling disappeared in 15 of 17 cases and relieved in 2 cases. Conclusion: There is good efficacy in the interventional treatment of left iliac vein lesions, but second-stage procedures should be performed in secondary lesions of saphenous veins and valves of femoral veins

Refractometry characteristics of α-quartz after neutron irradiation

International Nuclear Information System (INIS)

Abdkadyrova, I.Kh.

1997-01-01

Lattice structure distortions in irradiated crystalline quartz were studied by refractometry methods. The refractometry constants of α-quartz for the flux of fast neutrons 10 18 - 10 21 neutron/cm 2 were calculated. The critical kinetics of this constants at the phase transformation is observed.(author). 5 refs., 1 fig

Invisible gold in Colombian auriferous soils

International Nuclear Information System (INIS)

Bustos Rodriguez, H.; Oyola Lozano, D.; Rojas Martinez, Y. A.; Perez Alcazar, G. A.; Balogh, A. G.

2005-01-01

Optic microscopy, X-ray diffraction (XRD), Moessbauer spectroscopy (MS), Electron microprobe analysis (EPMA) and secondary ions mass spectroscopy (SIMS) were used to study Colombian auriferous soils. The auriferous samples, collected from El Diamante mine, located in Guachavez-Narino (Colombia), were prepared by means of polished thin sections and polished sections for EPMA and SIMS. Petrography analysis was made using an optical microscope with a vision camera, registering the presence, in different percentages, of the following phases: pyrite, quartz, arsenopyrite, sphalerite, chalcopyrite and galena. By XRD analysis, the same phases were detected and their respective cell parameters calculated. By MS, the presence of two types of pyrite was detected and the hyperfine parameters are: δ 1 = 0.280 ± 0.01 mm/s and ΔQ 1 = 0.642 ± 0.01 mm/s, δ 2 = 0.379 ± 0.01 mm/s and ΔQ 2 = 0.613 ± 0.01 mm/s. For two of the samples MS detected also the arsenopyrite and chalcopyrite presence. The mean composition of the detected gold regions, established by EPMA, indicated 73% Au and 27% Ag (electrum type). Multiple regions of approximately 200 x 200 μm of area in each mineral sample were analyzed by SIMS registering the presence of 'invisible gold' associated mainly with the pyrite and occasionally with the arsenopyrite.

Invisible gold in Colombian auriferous soils

Energy Technology Data Exchange (ETDEWEB)

Bustos Rodriguez, H., E-mail: hbustos@ut.edu.co; Oyola Lozano, D.; Rojas Martinez, Y. A. [Universidad del Tolima, Departamento de Fisica (Colombia); Perez Alcazar, G. A. [Universidad del Valle, Departamento de Fisica (Colombia); Balogh, A. G. [Darmstadt University of Technology, Institute of Materials Science (Germany)

2005-11-15

Optic microscopy, X-ray diffraction (XRD), Moessbauer spectroscopy (MS), Electron microprobe analysis (EPMA) and secondary ions mass spectroscopy (SIMS) were used to study Colombian auriferous soils. The auriferous samples, collected from El Diamante mine, located in Guachavez-Narino (Colombia), were prepared by means of polished thin sections and polished sections for EPMA and SIMS. Petrography analysis was made using an optical microscope with a vision camera, registering the presence, in different percentages, of the following phases: pyrite, quartz, arsenopyrite, sphalerite, chalcopyrite and galena. By XRD analysis, the same phases were detected and their respective cell parameters calculated. By MS, the presence of two types of pyrite was detected and the hyperfine parameters are: {delta}{sub 1} = 0.280 {+-} 0.01 mm/s and {Delta}Q{sub 1} = 0.642 {+-} 0.01 mm/s, {delta}{sub 2} = 0.379 {+-} 0.01 mm/s and {Delta}Q{sub 2} = 0.613 {+-} 0.01 mm/s. For two of the samples MS detected also the arsenopyrite and chalcopyrite presence. The mean composition of the detected gold regions, established by EPMA, indicated 73% Au and 27% Ag (electrum type). Multiple regions of approximately 200 x 200 {mu}m of area in each mineral sample were analyzed by SIMS registering the presence of 'invisible gold' associated mainly with the pyrite and occasionally with the arsenopyrite.

Dependence of red thermoluminescence on Eu-anomaly in natural quartzes

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, T; Yokosaka, K; Notoya, S; Ojima, T; Sakaue, S [Niigata Univ. (Japan). Faculty of Science

1993-04-01

The causes of red colour thermoluminescence (RTL) from natural quartz have been sought in the presence of impurity elements. Some impurities in 31 varieties of natural quartz extracts, determined by a neutron activation analysis, have been examined with respect to a meaningful correlation of the RTL to the total detectable TL strength. Generally, the higher impurity contents were found in quartz of volcanic origin, which always emits purely RTL colour, whereas the lower impurities were usually detected in hydrothermal quartz, which emits purely blue TL (BTL) in all absorbed doses. Among the impurities, the middle REE (rare earth elements), involving Eu and Sm, particularly offered considerable correlation with RTL emission with the exception of pegmatite quartz. It was found from the chondrite-normalized REE patterns that a positive Eu anomaly or flattened Eu distribution gave rise to relatively high RTL proportions, while a negative Eu anomaly always showed extremely weak RTL intensity. Thus, it was concluded that the Eu[sup 3+], formed from the oxidizable surrounding or high oxygen fugacity relative to a Cl chondrite formation, is strongly related to the RTL intensity in natural quartz. (author).

Superparamagnetic core/shell GoldMag nanoparticles: size-, concentration- and time-dependent cellular nanotoxicity on human umbilical vein endothelial cells and the suitable conditions for magnetic resonance imaging.

Science.gov (United States)

Gong, Mingfu; Yang, Hua; Zhang, Song; Yang, Yan; Zhang, Dong; Qi, Yueyong; Zou, Liguang

2015-03-25

GoldMag nanoparticles (GMNPs) possess the properties of colloid gold and superparamagnetic iron oxide nanoparticles, which make them useful for delivery, separation and molecular imaging. However, because of the nanometer effect, GMNPs are highly toxic. Thus, the biosafety of GMNPs should be fully studied prior to their use in biomedicine. The main purpose of this study was to evaluate the nanotoxicity of GMNPs on human umbilical vein endothelial cells (HUVECs) and determine a suitable size, concentration and time for magnetic resonance imaging (MRI). Transmission electron microscopy showed that GMNPs had a typical shell/core structure, and the shell was confirmed to be gold using energy dispersive spectrometer analysis. The average sizes of the 30 and 50 nm GMNPs were 30.65 ± 3.15 and 49.23 ± 5.01 nm, respectively, and the shell thickness were 6.8 ± 0.65 and 8.5 ± 1.36 nm, respectively. Dynamic light scattering showed that the hydrodynamic diameter of the 30 and 50 nm GMNPs were 33.2 ± 2.68 and 53.12 ± 4.56 nm, respectively. The r 2 relaxivity of the 50 nm GMNPs was 98.65 mM(-1) s(-1), whereas it was 80.18 mM(-1) s(-1) for the 30 nm GMNPs. The proliferation, cytoskeleton, migration, tube formation, apoptosis and ROS generation of labeled HUVECs depended on the size and concentration of GMNPs and the time of exposure. Because of the higher labeling rate, the 50 nm GMNPs exhibited a significant increase in nanotoxicity compared with the 30 nm GMNPs at the same concentration and time. At no more than 25 μg/mL and 12 hours, the 50 nm GMNPs exhibited no significant nanotoxicity in HUVECs, whereas no toxicity was observed at 50 μg/mL and 24 hours for the 30 nm GMNPs. These results demonstrated that the nanotoxicity of GMNPs in HUVECs depended on size, concentration and time. Exposure to larger GMNPs with a higher concentration for a longer period of time resulted in a higher labeling rate and ROS level for HUVECs. Coupled with r 2 relaxivity, it was suggested

Chemical changes during alteration of volcanic rocks and gold ore formation, La Libertad, Nicaragua

Science.gov (United States)

Darce, M.; Levi, B.; Nyström, J. O.

A chemical comparison between altered and unaltered basic lavas from a Tertiary epithermal gold deposit at La Libertad and its surroundings in central Nicaragua shows that chemical changes associated with the geothermal field type of alteration centered at the mining district reach more than 5 km away from it. Titanium seems to have been immobile, H 2O, CO 2, K, and S have been added, and Ni, Mg, and Cl partly lost from the fossil geothermal system. Gold, originally concentrated in the glass of basic lavas, was leached during zeolite facies conditions and precipitated with silica in fractures, forming veins in the center of the geothermal field. An estimate shows that the amount of Au released during the alteration was sufficient to form the La Libertad deposit.

Respirable dust and respirable silica exposure in Ontario gold mines.

Science.gov (United States)

Verma, Dave K; Rajhans, Gyan S; Malik, Om P; des Tombe, Karen

2014-01-01

A comprehensive survey of respirable dust and respirable silica in Ontario gold mines was conducted by the Ontario Ministry of Labor during 1978-1979. The aim was to assess the feasibility of introducing gravimetric sampling to replace the assessment method which used konimeters, a device which gave results in terms of number of particles per cubic centimeter (ppcc) of air. The study involved both laboratory and field assessments. The field assessment involved measurement of airborne respirable dust and respirable silica at all eight operating gold mines of the time. This article describes the details of the field assessment. A total of 288 long-term (7-8 hr) personal respirable dust air samples were collected from seven occupational categories in eight gold mines. The respirable silica (α-quartz) was determined by x-ray diffraction method. The results show that during 1978-1979, the industry wide mean respirable dust was about 1 mg/m(3), and the mean respirable silica was 0.08 mg/m(3.)The mean% silica in respirable dust was 7.5%. The data set would be useful in future epidemiological and health studies, as well as in assessment of workers' compensation claims for occupational diseases such as silicosis, chronic obstructive pulmonary disease (COPD), and autoimmune diseases such as renal disease and rheumatoid arthritis.

Formation of cogenetic quartz and nepheline syenites

Science.gov (United States)

Foland, K. A.; Landoll, J. D.; Henderson, C. M. B.; Chen, Jiangfeng

1993-02-01

Understanding the processes involved in the formation of cogenetic silica-undersaturated and silica-saturated felsic rocks in alkaline igneous complexes has been a long-standing enigma because of constraints imposed by phase equilibria relationships. This problem is discussed in general drawing upon relationships at two magmatic centers: Marangudzi in Zimbabwe and Mt. Brome in Quebec, Canada. At each locality, cogenetic quartz and nepheline syenites appear to be derived from common critically undersaturated magmas. Strontium and neodymium isotope results indicate that quartz syenites bear the signatures of substantial amounts of crustal assimilation whereas nepheline syenites lack or display lesser effects. In the model outlined, quartz syenite melts develop from felsic silica undersaturated magmas by assimilation of granitic crust coupled with fractional crystallization whereas nepheline syenites form without large amounts of contamination. This model is compatible with the constraints imposed by phase equilibria.

Identification of color development potential of quartz by Raman spectroscopy

International Nuclear Information System (INIS)

Alkmim, Danielle G.; Lameiras, Fernando S.; Almeida, Frederico O.T.

2013-01-01

Colorless quartz is usually exposed to ionizing radiation (gamma rays or high energy electron beams) to acquire different colors for jewelry. Color development is due to the presence of traces of some elements such as aluminum, iron, hydrogen, lithium, or sodium. Most quartz crystals are extracted colorless from nature and it is necessary to separate those that can develop colors from those that cannot. Irradiation tests can be used to accomplish this separation, but they take a long time. Infrared signature of colorless quartz can also be used. However, infrared spectroscopy is quite expensive, especially when using portable devices. Raman spectroscopy is now available as an inexpensive and portable technique that could provide identification of the samples of colorless quartz still in the field, facilitating the prediction for their economic exploitation. In addition, Raman spectroscopy usually requires a minimum or no sample preparation. This paper presents an investigation of the feasibility of using Raman spectroscopy as a substitute for infrared spectroscopy to predict the potential for color development of quartz. A band at 3595 cm -1 in the Raman shift spectrum was observed only along the c axis of a prasiolite excited by a high power 514 nm laser. This band was not observed in quartz samples that do not develop color after irradiation. Further studies are required to identify the potential for color development by Raman spectroscopy of other types of colorless quartz. (author)

Radioluminescence of synthetic quartz related to alkali ions

Energy Technology Data Exchange (ETDEWEB)

Martini, M., E-mail: m.martini@unimib.it [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); INFN-Sezione di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Fasoli, M. [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Galli, A. [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Istituto di Fotonica e Nanostrutture, IFN-CNR (Italy); Villa, I. [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Guibert, P. [IRAMAT-CRP2A (Institut de recherche sur les Archeomateriaux), UMR no. 5060, CNRS-Universite Bordeaux III, F-33607 Pessac (France)

2012-04-15

The radioluminescence (RL) of synthetic quartzes (GEMMA Quartz and Crystal Company) has been measured at room temperature. Some samples were treated by electrodiffusion ('sweeping') in order to change the concentrations of alkali ions, mainly Li{sup +} and Na{sup +}, which in quartz are known to be linked to Al ions, substitutional for Si ions. The RL emission spectra show evidence of a role of alkali ions in affecting some specific emissions. All the spectra could be analysed as composed of four bands in the blue and UV region. Specifically, the well known blue emission at around 470 nm was seen to be composed by two bands at 430 nm (2.86 eV) and at 485 nm (2.53 eV). Effects of irradiation, during the RL measurements, were clearly seen only in the 'Li swept in' sample, namely an increase in the 485 nm band intensity and a decrease in the 430 nm band one. The previously reported UV emission was detected at 355 nm (3.44 eV) in all the samples, being the most intense band in the 'swept out' sample. A further UV emission was detected at 315 nm (3.94 eV), more intense in untreated samples. Possible assignments of the detected emission bands are discussed in relation to the defects of quartz, specifically focusing on the Al centres that are most affected by sweeping procedures. - Highlights: Black-Right-Pointing-Pointer Contribution to the understanding of relationships between defects in quartz and luminescence emissions. Black-Right-Pointing-Pointer Role of charge compensators at substitutional Al sites in the optical properties of quartz. Black-Right-Pointing-Pointer Evidence of the double nature of the 'blue emission' (around 470 nm).

The angiographic demonstration of hepatic vein obstruction

International Nuclear Information System (INIS)

Zu Maoheng; Xu Hao; Li Guojun; Gu Yuming; Wei Ning; Wang Cheng; Xu Wei

2004-01-01

Objective: To evaluate the angiographic feature of hepatic vein obstruction. Methods Forty-five patients (male 23, female 22, age 9-54 years) suffered from hepatic vein obstruction. The inferior vena cavography and the hepatic venography were performed in all cases. Results: IVC was free in 37 patients with hepatic vein obstruction, both IVC and HV were obstructed in 8 patients. The local or long stenosis of IVC was found in 31 inferior vena cavography. The diameter of IVC was normal in 12 patients. The sign of membranous dome was found in hepatic vein orifice in 5 cases and in accessory hepatic vein orifice in 4 cases. Intrahepatic venous collaterals were found in 45 cases. Conclusion: Hepatic vein obstruction can be reproached primarily in inferior vena cavography, the membranous dome is a direct sign of membranous obstruction of HV and AHV in inferior vena cavography. The selected hepatic venography can provide reliable evidence to diagnose hepatic vein obstruction

Food irradiation dosimetry using thermoluminescence of quartz sand

International Nuclear Information System (INIS)

Khan, H.M.; Ehlermann, D.A.E.

1993-01-01

Thermoluminescence of quartz sand, which is inert and concomitant to several food materials, has been investigated for applications in food irradiation dosimetry and detection of irradiated foods. The glow curves consist of at least three overlapping peaks from 100 to 420 C. The peak at lower temperature is not stable and decays quickly at room temperature. However, the peaks at higher temperature are stable and more useful for dosimetry work. The intensity of the peak at 360 C, measured using different optical filters, shows a linear response in the range of 0.05 to 23 kGy. Stability of these signals at different annealing temperatures has been investigated. Thermoluminescence from adhering minerals and contaminating dust in different food materials has been found useful for the detection of irradiation treatment. Since quartz is frequently one of these minerals, further computerized deconvolution of individual glow peaks from the complex glow curves of quartz sand was carried out which improves the dosimetric results. Possible applications of thermoluminescence of quartz sand in food irradiation dosimetry and detection of irradiated foods have been discussed. (orig.)

Alpha efficiency determination for OSL of quartz extracted from Chinese loess

International Nuclear Information System (INIS)

Lai Zhongping; Zoeller, Ludwig; Fuchs, Markus; Brueckner, Helmut

2008-01-01

We report here the estimates of alpha efficiency for fine grain quartz extracted from Chinese loess using the SAR protocol. For the seven samples, the α-values range from 0.028 to 0.038 with an average of 0.035±0.001. The annealed quartz (450 deg. C, 45 min) has an α-value of 0.030±0.001 which is similar to the α-value of 0.029±0.001 for the non-annealed quartz extracts, suggesting that the α-value is independent of the quartz's thermal history for this sample. We suggest that an α-value of 0.035±0.003 can be adopted for quartz extracted from Chinese loess when calculating the environmental dose rate

A Vein Map Biometric System

Directory of Open Access Journals (Sweden)

Felix Fuentes

2013-08-01

Full Text Available There is increasing demand world-wide, from government agencies and the private sector for cutting-edge biometric security technology that is difficult to breach but userfriendly at the same time. Some of the older tools, such as fingerprint, retina and iris scanning, and facial recognition software have all been found to have flaws and often viewed negatively because of many cultural and hygienic issues associated with them. Comparatively, mapping veins as a human barcode, a new technology, has many advantages over older technologies. Specifically, reproducing a three-dimensional model of a human vein system is impossible to replicate. Vein map technology is distinctive because of its state-of-the-art sensors are only able to recognize vein patterns if hemoglobin is actively flowing through the person

Activation analysis of high pure quartz used as packing materials

International Nuclear Information System (INIS)

Luknitskij, V.A.; Morozov, B.A.

1979-01-01

A γ-spectrometric technique of neutron activation determination of microelements in quartz tubes used as a packing material for irradiation in reactors is reported. The analysis of 29 micro-admixtures in quartz tubes of USSR brands ''spectrtosil'' and ''KV'' was carried out. The γ-spectra of ''KV'' quartz irradiated by thermal and epithermal neutrons are presented. The activation by epithermal neutrons provides an activity gain for the nuclei whose resonance integral is high enough as compared to the activation cross-section with regard to thermal neutrons. The activation by epithermal neutrons permits additional determination of W, Cd, V, Th, Mn and Ni and provides for a substantial decrease in the activity of 24 Na, 42 K, 140 La, 46 Sc, 141 Ce, 51 Cr, and 59 Fe, which hinder the determination of the above-mentioned elements. The microelement composition of Soviet-made quartz varieties is compared to that of foreign-made quartz brands

Deep vein thrombosis of the leg

Energy Technology Data Exchange (ETDEWEB)

Lee, Eun Hee; Rhee, Kwang Woo; Jeon, Suk Chul; Joo, Kyung Bin; Lee, Seung Ro; Seo, Heung Suk; Hahm, Chang Kok [College of Medicine, Hanyang University, Seoul (Korea, Republic of)

1987-04-15

Ascending contrast venography is the definitive standard method for the diagnosis of deep vein thrombosis (DVT) of the lower extremities. Authors analysed 22 cases of DVT clinically and radiographically. 1.The patients ranged in age from 15 to 70 yrs and the most prevalent age group was 7th decade (31%). There was an equal distribution of males and females. 2.In 11 cases of 22 cases, variable etiologic factors were recognized, such as abdominal surgery, chronic bedridden state, local trauma on the leg, pregnancy, postpartum, Behcet's syndrome, iliac artery aneurysm, and chronic medication of estrogen. 3.Nineteen cases out of 22 cases showed primary venographic signs of DVT, such as well-defined filling defect in opacified veins and narrowed, irregularly filled venous lumen. In only 3 cases, the diagnosis of DVT was base upon the segmental nonvisualization of deep veins with good opacification of proximal and distal veins and presence of collaterals. 4.Extent of thrombosis: 3 cases were confined to calf vein, 4 cases extended to femoral vein, and 15 cases had involvement above iliac vein. 5.In 17 cases involving relatively long segment of deep veins, propagation pattern of thrombus was evaluated by its radiologic morphology according to the age of thrombus: 9 cases suggested central or antegrade propagation pattern and 8 cases, peripheral or retrograde pattern. 6.None of 22 cases showed clinical evidence of pulmonary embolism. The cause of the rarity of pulmonary embolism in Korean in presumed to be related to the difference in major involving site and propagation pattern of DVT in the leg.

Deep vein thrombosis of the leg

International Nuclear Information System (INIS)

Lee, Eun Hee; Rhee, Kwang Woo; Jeon, Suk Chul; Joo, Kyung Bin; Lee, Seung Ro; Seo, Heung Suk; Hahm, Chang Kok

1987-01-01

Ascending contrast venography is the definitive standard method for the diagnosis of deep vein thrombosis (DVT) of the lower extremities. Authors analysed 22 cases of DVT clinically and radiographically. 1.The patients ranged in age from 15 to 70 yrs and the most prevalent age group was 7th decade (31%). There was an equal distribution of males and females. 2.In 11 cases of 22 cases, variable etiologic factors were recognized, such as abdominal surgery, chronic bedridden state, local trauma on the leg, pregnancy, postpartum, Behcet's syndrome, iliac artery aneurysm, and chronic medication of estrogen. 3.Nineteen cases out of 22 cases showed primary venographic signs of DVT, such as well-defined filling defect in opacified veins and narrowed, irregularly filled venous lumen. In only 3 cases, the diagnosis of DVT was base upon the segmental nonvisualization of deep veins with good opacification of proximal and distal veins and presence of collaterals. 4.Extent of thrombosis: 3 cases were confined to calf vein, 4 cases extended to femoral vein, and 15 cases had involvement above iliac vein. 5.In 17 cases involving relatively long segment of deep veins, propagation pattern of thrombus was evaluated by its radiologic morphology according to the age of thrombus: 9 cases suggested central or antegrade propagation pattern and 8 cases, peripheral or retrograde pattern. 6.None of 22 cases showed clinical evidence of pulmonary embolism. The cause of the rarity of pulmonary embolism in Korean in presumed to be related to the difference in major involving site and propagation pattern of DVT in the leg

Gold film with gold nitride - A conductor but harder than gold

International Nuclear Information System (INIS)

Siller, L.; Peltekis, N.; Krishnamurthy, S.; Chao, Y.; Bull, S.J.; Hunt, M.R.C.

2005-01-01

The formation of surface nitrides on gold films is a particularly attractive proposition, addressing the need to produce harder, but still conductive, gold coatings which reduce wear but avoid the pollution associated with conventional additives. Here we report production of large area gold nitride films on silicon substrates, using reactive ion sputtering and plasma etching, without the need for ultrahigh vacuum. Nanoindentation data show that gold nitride films have a hardness ∼50% greater than that of pure gold. These results are important for large-scale applications of gold nitride in coatings and electronics

Bilateral meandering pulmonary veins

Energy Technology Data Exchange (ETDEWEB)

Thupili, Chakradhar R.; Udayasankar, Unni [Pediatric Imaging, Imaging Institute Cleveland Clinic, Cleveland, OH (United States); Renapurkar, Rahul [Imaging Institute Cleveland Clinic, Thoracic Imaging, L10, Cleveland, OH (United States)

2015-06-15

Meandering pulmonary veins is a rare clinical entity that can be mistaken for more complex congenital syndromes such as hypogenetic lung syndrome. We report imaging findings in a rare incidentally detected case of bilateral meandering pulmonary veins. We briefly discuss the role of imaging in diagnosing this condition, with particular emphasis on contrast-enhanced CT. (orig.)

Construction of simple quartz crystal microbalance

Energy Technology Data Exchange (ETDEWEB)

Ristov, Milcho [Center of Energy, Informatics and Materials of the Macedonian Academy fo Science and Arts, Skopje (Macedonia, The Former Yugoslav Republic of); Mitrevski, Mitre [Institute of Physics, Faculty of natural Science and Mathematics, Ss Cyril and Methodius University, Skopje (Macedonia, The Former Yugoslav Republic of)

2003-07-01

A very simple Quartz Crystal Microbalance (QCM) was constructed for the measurement of thickness of chemically deposited thin films. QCM consisted of two active elements: one dual-gate MOSFET and one bipolar transistor, and as usually two AT-cut quartz crystal. The beat frequency oscillation generated as a result of loading of the sensor crystal by the deposited thin film, was measured by HP-multimeter, set as a low frequency meter. The sensitivity was found to be high and satisfactory for the study of growth rate of thin films, mainly deposited by methods of chemical deposition.

Construction of simple quartz crystal microbalance