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Sample records for hydrothermal quartz veins

  1. Hydrothermal fluids and argon isotopes in quartz veins and cherts

    NASA Astrophysics Data System (ADS)

    Turner, Grenville

    1988-06-01

    Argon isotopes from a number of sources are present in quartz veins and chert; in situ decay of potassium, parentless 40Ar leached or outgassed from surrounding rocks, atmospheric argon dissolved in ancient hydrothermal fluids, and, modern atmospheric argon. The manner in which the 40Ar- 39Ar techniques can be used to unscramble these components, by way of correlations with Cl and K, is described in relation to two parallel studies of vein quartz and the Gunflint chert. Information concerning several processes can be inferred, including: contributions of surface waters to trapped fluids (from the concentration of atmospheric argon in the fluids), degree of water-rock interaction (from the concentration of parentless 40Ar and/or the ratio of parentless to atmospheric argon), effects of dilution of primary hydrothermal brines by meteoric water (which results in a decrease in the ratio of both Cl and parentless 40Ar to atmospheric argon), effects of boiling (from low concentrations of atmospheric argon and an increase in Cl/40Ar ). The K-Ar chronology of deposition can also be inferred in suitable circumstances. In principle, the ( 40Ar /36Ar ) ratio of the ancient atmosphere can be determined from fluids free of parentless 40Ar. However, a ( 40Ar /36Ar ) ratio determined for a low salinity end member in Gunflint chert probably reflects the presence of modern meteoric water.

  2. Trace elements in hydrothermal quartz: Relationships to cathodoluminescent textures and insights into vein formation

    USGS Publications Warehouse

    Rusk, B.G.; Lowers, H.A.; Reed, M.H.

    2008-01-01

    High-resolution electron microprobe maps show the distribution of Ti, Al, Ca, K, and Fe among quartz growth zones revealed by scanning electron microscope-cathodoluminescence (SEM-CL) from 12 hydrothermal ore deposits formed between ???100 and e1750 ??C. The maps clearly show the relationships between trace elements and CL intensity in quartz. Among all samples, no single trace element consistently correlates with variations in CL intensity. However in vein quartz from five porphyry-Cu (Mo-Au) deposits, CL intensity always correlates positively with Ti concentrations, suggesting that Ti is a CL activator in quartz formed at >400 ??C. Ti concentrations in most rutile-bearing vein quartz from porphyry copper deposits indicate reasonable formation temperatures of 2000 ppm, but in high-temperature quartz, Al concentrations are consistently in the range of several hundred ppm. Aluminum concentrations in quartz refl ect the Al solubility in hydrothermal fluids, which is strongly dependent on pH. Aluminum concentrations in quartz therefore reflect fluctuations in pH that may drive metal-sulfide precipitation in hydrothermal systems. ?? 2008 The Geological Society of America.

  3. Pre-biotic organic molecules in hydrothermal quartz veins from the Archaean Yilgarn province, Australia

    NASA Astrophysics Data System (ADS)

    Mayer, Christian; Schreiber, Ulrich; Dyker, Gerald; Kirnbauer, Thomas; Mulder, Ines; Sattler, Tobias; Schöler, Heinfried; Tubbesing, Christoph

    2013-04-01

    According to a model recently published by Schreiber et al. (OLEB 2012), pre-biotic organic molecules as earliest markers for a chemical evolution have been formed in tectonic faults of the first Archaean cratons. These faults are often documented by quartz- and other hydrothermal vein mineralization. During the growth of these quartzes, small portions of hydrothermal fluids are enclosed which conserve the chemical composition of the given fluid medium. According to our model, the preconditions for the geochemical formation of organic molecules are a suitable carbon source (e.g. carbon dioxide), varying P/T conditions, and catalysts. This given, rising hydrothermal fluids such as mineral-rich water and supercritical carbon dioxide in deep faults with contacts to the upper earth mantle offer conditions which allow for reactions similar to the Fischer-Tropsch synthesis. So far, the inclusions which possibly have conserved the products of these reactions have not been analyzed for possible organic constituents. First analytical results of a Mesozoic hydrothermal quartz vein from central Germany (Taunus) reveal that several organic compounds are found in fluid inclusions. However, the true origin of these compounds is unclear due to possible contamination by adjacent Corg-rich metasediments. Therefore, we have extended the study to hydrothermal quartz veins from the Archaean Yilgarn craton, to impact-generated quartz veins of the Shoemaker-Crater as well as to hydrothermal quartz boulders from a 2.7 to 3 billion years old conglomerate near Murchison (Western Australia). In one of the samples from the conglomerate, a wide spectrum of organic compounds such as bromomethane, butane, isoprene, benzene, and toluene have been detected. The time interval between the quartz formation, its erosion and its sedimentation is unknown. Possibly, the analyzed quartz sample was formed in a hydrothermal vein long before any living cells have existed on earth. In this case, the given

  4. Quantitative modeling of quartz vein sealing

    NASA Astrophysics Data System (ADS)

    Wendler, Frank; Okamoto, Atsushi; Schwarz, Jens-Oliver; Enzmann, Frieder; Blum, Philipp

    2014-05-01

    Mineral precipitation significantly effects many aspects of fluid-rock interaction across all length scales, as the dynamical change of permeability, of mechanical interaction and redistribution of dissolved material. The hydrothermal growth of quartz establishes one of the most important mineralization processes in fractures. Tectonically caused fracturing, deformation and fluid transport leaves clear detectable traces in the microstructure of the mineralized veins. As these patterns give hints on the deformation history and the fluid pathways through former fracture networks, accurate spatio-temporal modeling of vein mineralization is of special interest, and the objective of this study. Due to the intricate polycrystalline geometries involved, the underlying physical processes like diffusion, advection and crystal growth have to be captured at the grain scale. To this end, we adapt a thermodynamically consistent phase-field model (PFM), which combines a kinetic growth law and mass transport equations with irreversible thermodynamics of interfaces and bulk phases. Each grain in the simulation domain is captured by a phase field with individual orientation given by three Euler angles. The model evolves in discrete time steps using a finite difference algorithm on a regular grid, optimized for large grain assemblies. The underlying processes are highly nonlinear, and for geological samples, boundary conditions as well as many of the physical parameters are not precisely known. One motivation in this study is to validate the adequately parameterized model vs. hydrothermal experiments under defined (p,T,c) conditions. Different from former approaches in vein growth simulation, the PFM is configured using thermodynamic data from established geochemical models. Previously conducted batch flow experiments of hydrothermal quartz growth were analyzed with electron backscatter diffraction (EBSD) and used to calibrate the unknown kinetic anisotropy parameters. In the

  5. VOC and VOX in fluid inclusions of quartz: New chemical insights into hydrothermal vein mineralization by GC-MS and GC-IRMS measurements

    NASA Astrophysics Data System (ADS)

    Sattler, Tobias; Kirnbauer, Thomas; Keppler, Frank; Greule, Markus; Fischer, Jan; Spiekermann, Patrik; Schreiber, Ulrich; Mulder, Ines; Schöler, Heinz Friedrich

    2015-04-01

    Fluid inclusions (FIs) in minerals are known to contain a variety of different liquids, gases, and solids. The fluids get trapped during mineral growth and can preserve the original mineral-forming fluid or fluids of later events. A new analytical technique developed by Mulder et al. (2013) [1] allows to measure trace gases in FIs. For the measurements, grains of 3-5 mm diameter are ground in an airtight grinding device, releasing the volatiles from FIs into the gas phase, where they can be measured by GC-MS, GC-FID and GC-IRMS. The Taunus covers the southeastern part of the thrust-and-fold-belt of the Rhenish Massif (Germany). The Variscan rock sequences comprise sedimentary and volcanic units ranging from Ordovician to Lower Carboniferous. Several types of hydrothermal mineralization can be distinguished, which are - in regard to the Variscan orogeny - pre-orogenic, orogenic, late-orogenic, post-orogenic and recent in age [2]. They include SEDEX, vein, Alpine fissure, disseminated and stockwerk mineralizations. Thus, the Taunus mineralizations enable investigations of different hydrothermal systems at different age in one region. For most of them extensive studies of stable and radiogenic isotopes exist. Quartz crystals of post-orogenic quartz veins and Pb-Zn-Cu bearing veins [3] were selected for our FI investigation. Sulphur containing compounds like COS and CS2 dominate the FIs but there are also volatile hydrocarbons (VOC) like different butenes, benzene, toluene and cyclopentene that were found very often. In some samples volatile halogenated organic carbons (VOX) like chloro- and bromomethane were found. Some FIs even contain iodomethane, chlorobenzene, vinyl chloride and -bromide. The non-fossil-fuel subsurface chemistry of VOC and VOX is not fully understood. There are a lot of unknown geogenic sources [4][5]. For a better understanding δ13C- and δ2H-values of CH4 were measured by GC-IRMS to examine if the detected organic compounds are formed biotic

  6. Biogenic Iron-Rich Filaments in the Quartz Veins in the Uppermost Ediacaran Qigebulake Formation, Aksu Area, Northwestern Tarim Basin, China: Implications for Iron Oxidizers in Subseafloor Hydrothermal Systems.

    PubMed

    Zhou, Xiqiang; Chen, Daizhao; Tang, Dongjie; Dong, Shaofeng; Guo, Chuan; Guo, Zenghui; Zhang, Yanqiu

    2015-07-01

    Fe-(oxyhydr)oxide-encrusted filamentous microstructures produced by microorganisms have been widely reported in various modern and ancient extreme environments; however, the iron-dependent microorganisms preserved in hydrothermal quartz veins have not been explored in detail because of limited materials available. In this study, abundant well-preserved filamentous microstructures were observed in the hydrothermal quartz veins of the uppermost dolostones of the terminal-Ediacaran Qigebulake Formation in the Aksu area, northwestern Tarim Basin, China. These filamentous microstructures were permineralized by goethite and hematite as revealed by Raman spectroscopy and completely entombed in chalcedony and quartz cements. Microscopically, they are characterized by biogenic filamentous morphologies (commonly 20-200 μm in length and 1-5 μm in diameter) and structures (curved, tubular sheath-like, segmented, and mat-like filaments), similar to the Fe-oxidizing bacteria (FeOB) living in modern and ancient hydrothermal vent fields. A previous study revealed that quartz-barite vein swarms were subseafloor channels of low-temperature, silica-rich, diffusive hydrothermal vents in the earliest Cambrian, which contributed silica to the deposition of the overlying bedded chert of the Yurtus Formation. In this context, this study suggests that the putative filamentous FeOB preserved in the quartz veins might have thrived in the low-temperature, silica- and Fe(II)-rich hydrothermal vent channels in subseafloor mixing zones and were rapidly fossilized by subsequent higher-temperature, silica-rich hydrothermal fluids in response to waning and waxing fluctuations of diffuse hydrothermal venting. In view of the occurrence in a relatively stable passive continental margin shelf environment in Tarim Block, the silica-rich submarine hydrothermal vent system may represent a new and important geological niche favorable for FeOB colonization, which is different from their traditional

  7. Relationship between amorphous silica and precious metal in quartz veins

    NASA Astrophysics Data System (ADS)

    Harrichhausen, N.; Rowe, C. D.; Board, W. S.; Greig, C. J.

    2015-12-01

    Super-saturation of silica is common in fault fluids, due to pressure changes associated with fracture, fault slip, or temperature gradients in hydrothermal systems. These mechanisms lead to precipitation of amorphous silica, which will recrystallize to quartz under typical geologic conditions. These conditions may also promote the saturation of precious metals, such as gold, and the precipitation of nanoparticles. Previous experiments show that charged nanoparticles of gold can attach to the surface of amorphous silica nanoparticles. Thus, gold and silica may be transported as a colloid influencing mineralization textures during amorphous silica recrystallization to quartz. This may enrich quartz vein hosted gold deposits, but the instability of hydrous silica during subsequent deformation means that the microstructural record of precipitation of gold is lost. We investigate a recent, shallow auriferous hydrothermal system at Dixie Valley, Nevada to reveal the nano- to micro-scale relationships between gold and silica in fresh veins. Fault slip surfaces at Dixie Valley exhibit layers of amorphous silica with partial recrystallization to quartz. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) show amorphous silica can contain a few wt. % gold while areas recrystallized to quartz are barren. At the Jurassic Brucejack deposit in British Columbia, Canada we observe the cryptocrystalline quartz textures that may indicate recrystallization from amorphous silica within quartz-carbonate veins containing high grade gold. Comb quartz within syntaxial veins, vugs, and coating breccia clasts indicate structural dilation. Vein geometry is investigated to determine relative importance of fault slip in creating dilational sites. By comparing quartz-carbonate veins from the Dixie Valley to Brucejack, we can determine whether amorphous silica formed in different environments show similar potential to affect precious metal mineralization.

  8. Quartz-molybdenite veins in the Priestly Lake granodiorite, north-central Maine

    USGS Publications Warehouse

    Ayuso, Robert A.; Shank, Stephen G.

    1983-01-01

    Quartz-molybdenite veins up to 15 cm in width occur in fine to medium-grained porphyritic biotite-hornblende granodiorite at Priestly Lake north-central Maine. An area of about 150 m x 150 m contains quartz-molybdenite veins; a larger area is characterized by barren quartz veins. Quartz-molybdenite veins are concentrated within the most felsic variants of the intrusion as suggested by lower mafic mineral contents. The pluton has a narrow range in SiO2 (67-70 wt.%), major oxides, and in trace-element compositions. Molybdenite occurs as coarse grained clusters in pockets within the quartz veins, and fills fractures in the quartz veins and host rocks. Disseminated molybdenite in the granodiorite is relatively rare and occurs only in the area characterized by a high density of quartz veins (up to 50 veins per square meter). Alteration envelopes along the quartz veins are very thin or absent, although in some areas the granodiorite appears to be selectively and pervasively altered. Sericite, chlorite, epidote, calcite, pyrite, and quartz are concentrated near the quartz-molybdenite veins. Many of the field and geochemical characteristics of the Priestly Lake pluton are unlike those of major molybdenum-producing areas (Climax, Henderson, Urad). For example, the area of alteration seems to be of limited extent, the host rock is not intensely altered hydrothermally at the surface, the density of fractures is rather low in the mineralized area, and the amount of disseminated molybdenite appears to be small. However, the Priestly Lake pluton may be a small fraction of a concealed batholith as suggested by geophysical data. It is conceivable that the type of mineralization at the surface might be the expression of more extensive molybdenite mineralization at depth. The quartz-molybdenite veins in the Priestly Lake pluton are significant because they indicate that potential molybdenum sources for producing mineralized granites were available at depth. Future studies should be

  9. Ion-microprobe dating of zircon from quartz-graphite veins at the Bristol, New Hampshire, metamorphic hot spot

    SciTech Connect

    Zeitler, P.K. ); Barreiro, B.; Chamberlain, C.P. ); Rumble, D. III )

    1990-07-01

    Detrital zircons entrained in hydrothermal quartz-graphite-rutile veins found near the Bristol, New Hampshire, metamorphic hot spot are overgrown by thin rims. Ion-microprobe analyses of these rims date their growth at 408 {plus minus} 6 Ma. These measurements quantitatively confirm textural evidence that the graphite veins were emplaced during peak metamorphism associated with the Acadian orogeny, and they provide a direct positive test of the hypothesis, based on petrological and stable-isotope evidence, that the hydrothermal systems responsible for the quartz-graphite veins were also responsible for the hot-spot metamorphism.

  10. A discussion of 'Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?'

    NASA Technical Reports Server (NTRS)

    Roedder, Edwin

    1990-01-01

    This paper presents arguments against the statement made by Koeberl et al. (1989) to the effect that various differences between the quartz of the three quartz pebbles from the Roter Kamm impact crater (Namibia) and the quartz of the pegmatites present in the basement rocks of this crater can be best interpreted as evidence that the pebbles were formed (or 'recrystallized') by a post-impact hydrothermal system. Arguments are presented that suggest that the three quartz pebbles are, most likely, fragments of a preimpact vein quartz of hydrothermal origin.

  11. A discussion of 'Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?'

    NASA Astrophysics Data System (ADS)

    Roedder, Edwin

    1990-11-01

    This paper presents arguments against the statement made by Koeberl et al. (1989) to the effect that various differences between the quartz of the three quartz pebbles from the Roter Kamm impact crater (Namibia) and the quartz of the pegmatites present in the basement rocks of this crater can be best interpreted as evidence that the pebbles were formed (or 'recrystallized') by a post-impact hydrothermal system. Arguments are presented that suggest that the three quartz pebbles are, most likely, fragments of a preimpact vein quartz of hydrothermal origin.

  12. Cathodoluminescence investigation and fluid inclusion analyses of hydrothermal quartz in the Erdenetiin Ovoo porphyry Cu-Mo deposit in Northern Mongolia

    NASA Astrophysics Data System (ADS)

    Cha, B.; Lee, I.; Seo, J.; Moon, I.

    2012-12-01

    Scanning electron microscope-cathodoluminescence (SEM-CL) reveals textures in quartz that are not apparent with other methods such as optical microscopy or backscattered electron images. Hydrothermal quartz from quartz-sulfide veins in the Erdenetiin Ovoo porphyry Cu-Mo deposit, Mongolia was analyzed by SEM-CL. They reveal euhedral growth zones with CL-bright and gray, wide CL-dull bands that cut across multiple quartz grains, CL-dark splatters of quartz connected by networks of cobweb-shaped CL-dark quartz with decreasing in luminescence along splatters and grain boundaries, and recrystallization of CL-bright quartz to CL-gray quartz. These cryptic textures indicate that a single vein of molybdenite-quartz vein has undergone at least 4 events: (1) precipitation of CL-bright and CL-gray quartz with euhedral quartz, (2) fracturing and following growth of CL-dull quartz, (3) dissolution along microfractures and following CL-dark precipitation with decreasing in luminescence intensity along microfractures and grain boundaries, and (4) precipitation of pyrite-quartz vein cutting the molybdenite-quartz vein. Fluid inclusions in molybdenite-quartz veins are presented by liquid type, liquid-vapor type (vapor occupies 20 volume %), and liquid-vapor type bearing a solid phase. The liquid-vapor type inclusions within CL-gray quartz of the first event show their homogenization temperatures ranging from 204 to 312°C. Typical homogenization temperatures of porphyry deposits range from 250 to 800°C. Molybdenite-quartz vein in the Erdenetiin Ovoo porphyry system formed through the low temperature hydrothermal processes. Keywords: Erdenetiin Ovoo, hydrothermal, quartz, veins, cathodoluminescence, fluid inclusions

  13. A fluid inclusion and light element stable isotope study of the gold-bearing quartz vein system, Falun, Sweden

    NASA Astrophysics Data System (ADS)

    Åberg, A.; Fallick, A. E.

    1993-11-01

    The Falun gold quartz vein mineralization is located ca 230 km NW of Stockholm, Sweden, within the Early Proterozoic volcano-sedimentary sequence of Bergslagen. The mineralization consists of a system with subparallel quartz veins that crosscut the alteration zone to the Falun massive sulphide deposit. Early barren and late gold-bearing quartz veins follow tectonic structures postdating the formation of the massive sulphide ore. Both generations of veins are epigenetic to the massive sulphide ore and were formed by hydrothermal processes. Fluid inclusion study of the gold-bearing quartz veins indicates a low-moderately saline fluid (0.3 to 17.4 equiv wt% NaCl). Heterogeneous trapping is indicated by coexisting inclusions showing a variable CO2 content from 100% CO2 ± CH4 to 100% aqueous fluid. Temperatures of total homogenization also show a wide spread from 116-350°C with a slightly bimodal distribution with peaks at ca 180°C and 280°C. Measured δD values — 69 to — 63%0 (SMOW), of inclusion fluid and calculated δ 18O values of hydrothermal fluids — 7.5 to — 1.4%0 (SMOW), strongly suggest a meteoric origin for the fluids. The quite consistent δD values and the range in δ 18O values indicate that major water-rock interaction led to the evolution in δ18O of the hydrothermal fluids.

  14. Genetic significance of the trace element content in metamorphic and hydrothermal quartz: a reconnaissance study

    NASA Astrophysics Data System (ADS)

    Monecke, T.; Kempe, U.; Götze, J.

    2002-09-01

    A reconnaissance study on trace elements in metamorphic and hydrothermal quartz was carried out using quartz samples from the tin district Erzgebirge, Germany, the gold mineralization at Ka\\vsperské Hory, Czech Republic, and the gold-quartz vein deposits Muruntau and Myutenbai, Uzbekistan. A new method of sample preparation has been developed to prepare pure quartz samples by combining conventional hand-picking with microscopic and spectroscopic studies as well as acid wash/etch procedures. Preparation of monomineralic samples was followed by sample dissolution and measurement by ICP-MS. The metamorphic quartz has very low concentrations of Li (≤0.4 ppm), Al (≤30 ppm), K (≤35 ppm), Rb (≤50 ppb), Sr (≤0.3 ppm), and Y (≤15 ppb). Moreover, it is characterized by light rare earth element enriched lanthanide distribution patterns lacking Eu anomalies. The low element concentrations in metamorphic quartz are interpreted to result from recrystallization. Metamorphic quartz from alteration halos enveloping tin and gold deposits has distinctly different trace element signatures. These differences are related to the hydrothermal overprint of the pre-existing metamorphic quartz by the mineralizing fluids. Hydrothermally altered metamorphic quartz from tin deposits has elevated concentrations of Li (≥0.9 ppm), Al (≥50 ppm), K (≥45 ppm), Rb (≥250 ppb), and Y (≥40 ppb) whereas altered metamorphic quartz from gold deposits is characterized by elevated concentrations of Sr (≥0.5 ppm). The rare earth element distribution patterns of altered metamorphic quartz show variable enrichments of the heavy rare earth elements and frequently display positive Eu anomalies. Hydrothermal vein quartz from the gold deposits usually has elevated Al (≥50 ppm) and Sr (≥0.6 ppm) contents. The lanthanide distribution patterns exhibit variable enrichments of the heavy rare earth elements and commonly show positive Eu anomalies. The elevated Sr concentrations in the quartz

  15. Porosity structures in synthetic quartz veins examined by micro X-ray CT

    NASA Astrophysics Data System (ADS)

    Yamada, R.; Okamoto, A.; Saishu, H.; Nakamura, M.; Okumura, S.; Sasaki, O.; Tsuchiya, N.

    2013-12-01

    Ubiquitous occurrences of quartz veins suggest that dissolution/precipitation of silica provides significant effects on the hydrological and mechanical properties within the crust. For example, a model has been proposed that fracture sealing processes control the change of pore fluid pressure and thus earthquake cycle. Previous studies on natural quartz veins have focused on estimates of P-T conditions, stress and strain fields and fluid compositions; however, details of dynamics of fluid flow and how fractures are sealed during vein formation are still unclear. In this study, we synthesized quartz veins by the hydrothermal experiments, and observed the aperture structures by using X-ray CT. The purpose of this study is to clarify how aperture structures evolve during vein formation especially focusing on effect of the state of water (vapor and supercritical region). We conducted the hydrothermal flow-through experiments for quartz precipitation from Si-supersaturated solutions under supercritical (430C, 30MPa) and vapor condition (370C, 20MPa). The experimental apparatus consists of two vessels for preparation of the Si-supersaturated solution and for precipitation, respectively. The precipitation vessel has double-structure: the main flow path was the inner alumina tube (diameter=4mm), and the outer SUS tube was filled with static solutions. Two situations were examined as the inner tubes; one is porous media composed of closed packed alumina balls(1mm in size), and the other one is fracture. The advantage of this system is that we can take out the non-destructive sample for the analyses by X-ray CT. Significant porosity reduction by silica precipitation at porous media. Under supercritical condition, amorphous silica was predominantly formed with covering the surfaces of the alumina balls and alumina tube, and discrete quartz crystal (50μm) within the amorphous silica layers. The porosity (Φ) gradually decreases with minimal porosity (Φ = 0.4) at ˜ 38mm from

  16. Formation of Quartz-Carbonate Veins: Evidence From Experimental Supercritical Carbon Dioxide-Brine-Rock System

    NASA Astrophysics Data System (ADS)

    Janecky, D. R.; Kaszuba, J. P.

    2003-12-01

    Quartz-carbonate veins are common in a variety of moderate temperature hydrothermal systems and ore deposits. Associated fluid inclusions have a wide range of compositions, including liquid carbon dioxide fillings. Examination of chemical and physical conditions which result precipitation of quartz and carbonate in veins raises several key questions about multiphase fluid processes and reaction rates. We have been experimentally investigating physical-chemical reaction processes of mixed brine-carbon dioxide fluids for the shallow crust. Synthetic arkose (microcline + oligoclase + quartz + biotite) plus argillaceous shale were reacted with 5.5 molal NaCl brine. The system was held at 200 C and 200 bars for 32 days to approach steady state, then injected with carbon dioxide and allowed to react for an additional 45 days. In a parallel experiment, the system was allowed to react for 77 days without injection of carbon dioxide. Trace ions initially absent from NaCl brine appeared in solution at mM (K, Ca, and silica) to uM (Mg, Al, Fe and Mn) quantities, reflecting reaction of brine with rock. Without carbon dioxide injection, the silica concentration (2.4 mM) was stable below calculated quartz solubility (3.9 mM). Injection of carbon dioxide resulted in decreased pH and increased silica concentration to a level near calculated chalcedony solubility (5.4 mM). Dissolution of silicate minerals is apparently coupled to the acidity, and concomitant inhibition of the precipitation of quartz (and other silicates). A significant increase in concentration of trace metals is consistent with in-situ pH decrease and increased carbon dioxide dissolved in brine. Multi-phase fluid reaction relationships between supercritical carbon dioxide and brine-rock systems allow formation of carbonate vein precipitates in substantial quantities. Brine and continued rock reactions provide a substantial reservoir for Ca, Mg and Fe components. A separate carbon dioxide liquid allows

  17. Emerald mineralization and metasomatism of amphibolite, khaltaro granitic pegmatite - Hydrothermal vein system, Haramosh Mountains, Northern Pakistan

    USGS Publications Warehouse

    Laurs, B.M.; Dilles, J.H.; Snee, L.W.

    1996-01-01

    Emerald mineralization is found within 0.1- to 1-m-thick hydrothermal veins and granitic pegmatites cutting amphibolite within the Nanga Parbat - Haramosh massif, in northern Pakistan. The amphibolite forms a sill-like body within garnet-mica schist, and both are part of a regional layered gneiss unit of Proterozoic (?) age. The 40Ar/39Ar data for muscovite from a pegmatite yield a plateau age of 9.13 ?? 0.04 Ma. Muscovite from mica schist and hornblende from amphibolite yield disturbed spectra with interpreted ages of 9 to 10 Ma and more than 225 Ma, respectively, which indicate that peak Tertiary metamorphism reached 325 to 550??C prior to 10 Ma. Pegmatites were emplaced after peak metamorphism during this interval and are older than pegmatites farther south in the massif. At Khaltaro, simply zoned albite-rich miarolitic pegmatites and hydrothermal veins containing various proportions of quartz, albite, tourmaline, muscovite, and beryl are associated with a 1- to 3-m-thick heterogeneous leucogranite sill, that is locally albitized. The pegmatites likely crystallized at 650 to 600??C at pressures of less than 2 kbar. Crystals of emerald form within thin (0.20, 0.54-0.89 wt%), to pale blue beryl (<0.07, 0.10-0.63%), to colorless beryl (<0.07, 0.07-0.28%). The amphibolite is metasomatized in less than 20-cm-wide selvages that are symmetrically zoned around veins or pegmatites. A sporadic inner zone containing F-rich biotite, tourmaline, and fluorite, with local albite, muscovite, quartz, and rare beryl, gives way to an intermediate zone containing biotite and fluorite with local plagioclase and quartz, and to an outer zone of amphibolite containing sparse biotite and local quartz. The inner and intermediate zones experienced gains of K, H, F, B, Li, Rb, Cs, Be, Ta, Nb, As, Y and Sr, and losses of Si, Mg, Ca, Fe, Cr, V and Sc. The outer alteration zone has gained F, Li, Rb, Cs, and As. Oxygen isotope analyses of igneous and hydrothermal minerals indicate that a

  18. SIMS Investigations on Growth and Sector Zoning in Natural Hydrothermal Quartz: Isotopic and Trace Element Analyses

    NASA Astrophysics Data System (ADS)

    May, E.; Vennemann, T. W.; Baumgartner, L. P.; Meisser, N.

    2014-12-01

    Quartz is the most abundant mineral in the Earth's crust and is found in virtually every geological context. Despite its ubiquity and the detailed studies on the conditions of quartz crystallization, some questions concerning its growth and sector zoning with regard to trace element incorporation and oxygen isotope fractionations and the implications thereof for interpretations on the conditions of formation remain (e.g., Jourdan et al., 2009). This study presents new in-situ measurements of trace element and oxygen isotope ratios on natural hydrothermal quartz from an extensional gold-bearing quartz vein in the western Swiss Alps. The temperature of formation of the veins is estimated by quartz-hematite oxygen isotope thermometry to be about 360°C. A detailed SEM-CL study of this sample shows cyclic lamellar growth, alternating with phases of dissolution that are directly followed by macro-mosaic growth of the quartz, before returning to a cyclic lamellar growth again. Trace element concentrations (measured for Na, K, Li, Al, and Ti) notably showed Al/Si variations of three orders of magnitude and coupled Al and Li variations, likely substituting for Si in different growth zones with lower values in macro-mosaic zones precipitating after the period of dissolution. The oxygen isotope composition of the crystal, in contrast, is homogeneous through all growth zones (δ18O values between 15.6‰ and 16.2‰) indicating that the fluid must have been buffered by the host-rock and/or the source of the fluid remained the same despite the period of quartz dissolution. Furthermore, the temperature during crystallization of the quartz crystal has likely also remained similar. The fact that no variations are measured in oxygen isotope compositions but some variations in trace element contents may suggest that changes in pressure were important during the formation of this quartz crystal. Give the pressure effects on the solubility of quartz (Fournier and Potter, 1982), both

  19. Oxygen isotopic composition of quartz veins and host rocks at the Sukhoi Log deposit, Russia

    NASA Astrophysics Data System (ADS)

    Ikonnikova, T. A.; Dubinina, E. O.; Saroyan, M. R.; Chugaev, A. V.

    2009-12-01

    The relationships between the δ18O of quartz veins and veinlets pertaining to the main stage of gold mineralization at the Sukhoi Log deposit and metasomatically altered host slates are estimated. The oxygen isotopic composition of veined quartz and host slates is not uniform. The δ18O of quartz veins from the Western, Central, and Sukhoi Log areas of the deposit vary from +16 to + 18 ‰. The δ18O range of metasomatically altered slates in the Western and Sukhoi Log areas attains 6 ‰. The δ18O of quartz veins are always higher than those of host slates by 3-7‰. The regular difference in the δ18O between quartz veins and host slates indicates that the oxygen isotopic composition of the ore-bearing fluid forming the system of quartz veins and veinlets at the Sukhoi Log deposit could have formed as a result of interaction with silicate rocks, for instance, terrigenous slates enriched in δ18O. Such interaction, however, took place at deeper levels of the Sukhoi Log deposit. It is suggested that the fluid phase participating in the formation of the vein and veinlet system had initially high δ18O(>+10‰) due to interaction with the rocks enriched in δ18O at a low fluid/rock ratio. The oxygen isotope data indicate that the fluid participating in the formation of gold mineralization at the Sukhoi Log deposit was not in equilibrium with igneous rocks at high temperatures.

  20. Investigating Alpine fissure rutilated quartz to constrain timing and conditions of post-metamorphic hydrothermal fluid flow

    NASA Astrophysics Data System (ADS)

    Shulaker, D. Z.; Schmitt, A. K.; Zack, T.; Bindeman, I. N.

    2013-12-01

    Rutilated quartz, aka Venus' hair, is finely-acicular rutile intergrown with host quartz generated by fluid-mediated co-crystallization. It is commonly found in hydrothermal veins, including the renown cleft mineral locations of the Swiss Alps. Previous studies of Alpine cleft mineralizations used rare hydrothermal monazite [1] and titanite [2] to constrain vein formation to ~13.5-15.2 Ma, postdating peak metamorphism by ~2-4 Ma. Temperature (T) estimates of 150-450°C are based on fluid inclusions and bulk quartz-mineral oxygen isotope exchange equilibria, and formation pressures (P) are 0.5-2.5 kbar (for a geothermal gradient of 30°C/km) [2]. The potential of rutilated quartz as a thermochronometer, however, has not been harnessed previously. Here, we present the first results of age and P-T determinations for rutilated quartz from six locations in the Swiss Alps (San Gottardo; Feldbach, Binntal; Pi Aul, Vals; Faido, Leventina; Elm, Steinbach; Binntal). Samples were cut and mounted in epoxy discs to expose rutile (0.03 to 1 mm in diameter) and its host quartz which was also imaged in cathodoluminescence (CL). CL images for half of the samples' host quartz exhibited strong sector zoning, while others reveal only weak CL zonation. Isotopic and trace element analyses were carried out by SIMS using a CAMECA ims1270 for U-Pb, O-isotopes, and Ti-in-quartz, and a LA-ICP-MS system (213 nm New Wave laser coupled to an Agilent 7500a) for Zr-in-rutile. U-Pb rutile ages average 15.5×2.0 Ma (2σ). T estimates are 352-575°C (rutile-quartz oxygen isotopes in touching domains), 470-530°C (Zr-in-rutile assuming P = 0.5 and equilibrium with host-rock zircon), and 251-391°C (Ti-in-quartz at assumed P = 0.5 kbar and aTiO2 = 1). CL zones are isotopically unzoned. Rutile-quartz oxygen isotopes are pressure insensitive, whereas Zr-in-rutile and Ti-in-quartz are minimum temperatures. These results demonstrate that rutilated quartz can constrain timing and conditions of post

  1. Brittle-viscous deformation of vein quartz under fluid-rich lower greenschist facies conditions

    NASA Astrophysics Data System (ADS)

    Kjøll, H. J.; Viola, G.; Menegon, L.; Sørensen, B. E.

    2015-06-01

    We studied by Electron BackScatter Diffraction (EBSD) and optical microscopy a coarse-grained (ca. 0.5-6 mm) quartz vein embedded in a phyllonitic matrix to gain insights into the recrystallization mechanisms and the processes of strain localization in quartz deformed under lower greenschist facies conditions, broadly coincident with the brittle-viscous transition. The vein deformed during faulting along a phyllonitic thrust of Caledonian age within the Porsa Imbricate Stack in the Paleoproterozoic Repparfjord Tectonic Window in northern Norway. The phyllonite hosting the vein formed at the expense of a metabasaltic protolith through feldspar breakdown to form interconnected layers of fine, synkinematic phyllosilicates. In the mechanically weak framework of the phyllonite, the quartz vein acted as a relatively rigid body. Viscous deformation in the vein was initially accommodated by quartz basal slip. Under the prevailing deformation conditions, however, dislocation glide- and possibly creep-accommodated deformation of quartz was inefficient, and this resulted in localized strain hardening. In response to the (1) hardening, (2) progressive and cyclic increase of the fluid pressure, and (3) increasing competence contrast between the vein and the weakly foliated host phyllonite, vein quartz crystals began to deform by brittle processes along specific, suitably oriented lattice planes, creating microgouges along microfractures. Nucleated new grains rapidly sealed these fractures as fluids penetrated the actively deforming system. The grains grew initially by solution precipitation and later by grain boundary migration. We suggest that the different initial orientation of the vein crystals led to strain accommodation by different mechanisms in the individual crystals, generating remarkably different microstructures. Crystals suitably oriented for basal slip, for example, accommodated strain mainly viscously and experienced only minor fracturing. Instead, crystals

  2. Quartz veining in slates and Variscan deformation: Insights from the Luarca sector (NW Spain)

    NASA Astrophysics Data System (ADS)

    Pérez-Alonso, J.; Fuertes-Fuente, M.; Bastida, F.

    2016-03-01

    A structural and geochemical analysis of quartz veins is made in order to determine their evolution and the physical-chemical conditions that enabled their development. In this sector of the Variscan belt (Westasturian-Leonese Zone), three phases of deformation have been described. However, only the first and third phases are represented in the study sections. The first phase (D1) resulted in tight or closed folds (F1) verging towards the foreland and associated slaty cleavage (S1). The third phase (D3) resulted in approximately upright asymmetric folds (F3) with associated crenulation cleavage (S3). The veins are hosted in slates and approximately follow the slaty cleavage (S1). The veins started their development at the beginning of the deformation phase D3 as a result of S1 near parallel shortening. Through a process of progressive deformation, this compression gave rise to the folding of the cleavage and, eventually, of the veins. The F3 folds have associated crenulation cleavage parallel to the axial planes. In some cases, the location of the veins was controlled by irregularities in the bedding due to sedimentary structures. The quartz of the veins underwent notable intracrystalline plastic deformation, and the contact zone between the veins and the host rock was affected by pressure solution. The microstructures produced by the latter mechanism indicate the greatest compressive stress forming a high angle with the vein walls at a time post-dating vein generation. Quartz precipitated from an aqueous-carbonic fluid at temperatures between 350 °C and 375 °C under fluid pressure fluctuations of up to 140 MPa at constant depth. Maximum values of fluid pressure of 220 MPa and minimum values of 75 MPa were recorded by fluid inclusion assemblages in quartz of the veins under study. Pressure fluctuation from lithostatic to infralithostatic at constant depth was caused by the opening and sealing of the dilatant fractures.

  3. Giant quartz vein systems in accretionary orogenic belts: the evidence for a metamorphic fluid origin from δ 15N and δ 13C studies

    NASA Astrophysics Data System (ADS)

    Jia, Yiefei; Kerrich, Robert

    2000-12-01

    Nitrogen isotope compositions of hydrothermal micas in giant structurally hosted quartz vein systems place constraints on the origin of the hydrothermal fluids. The vein systems are from Neoarchean terranes in the Superior Province of Canada, and the Norseman terrane, Western Australia. The four quartz vein systems studied in different terranes formed at metamorphic grades ranging from lower greenschist to lower amphibolite facies, coevally with metamorphism of the host terrane. Nitrogen resides predominantly as NH 4+ in hydrothermal mica. For lower to upper greenschist facies quartz veins, N contents and δ 15N values of micas are between 40 and 200 ppm and 15‰ and 21‰, respectively, whereas in quartz veins formed at the greenschist to amphibolite transition and lower amphibolite facies, micas have N contents of 20-70 ppm and δ 15N of 11-24‰. In contrast, micas and K-feldspars from granitoids in the Neoarchean Abitibi and Red Lake greenstone belts are characterized by systematically lower δ 15N of -5‰ to 5‰, and generally lower N contents of 20-50 ppm, comparable to other granitoids. Carbon and oxygen isotope compositions of hydrothermal ferroan dolomite and calcite show systematic depletions with increasing metamorphic grade. The mean values range from -2.2‰ to -3.7‰ for δ 13C and 13.8‰ to 12.3‰ for δ 18O in veins formed at lower to upper greenschist facies, but from -5.8‰ to -7.1‰ for δ 13C and 11.4‰ to 9.8‰ for δ 18O at higher metamorphic grades. Nitrogen isotope compositions rule out mantle (δ 15N mean=-5‰), magmatic (δ 15N=-5‰ to <10‰), or meteoric fluids (δ 15N mean=4.4±2.0‰) for the quartz veins. Accordingly, the results are consistent with fluids derived from metamorphic dehydration of oceanic crust and sediments within accretionary orogenic belts.

  4. Hydrothermal geochemistry of silver-gold vein formation in the Tayoltita mine and San Dimas mining district, Durango and Sinaloa, Mexico

    SciTech Connect

    Clarke, M.

    1986-01-01

    The San Dimas mining district, including the Tayoltita mine, is a Tertiary silver-gold epithermal vein system deposited in a calcalkaline volcanic pile. Hydrothermal alteration and vein formation is temporally related to a granite batholith intruded into the volcanics. Alteration mineralogy in andesites is compatible with a hydrothermal flow model in which heated water rises through the batholith, cools to 260 C, and flows out into the volcanics. Lateral elongation of Ag:Au ratio zoning plotted on vertical projections of veins is interpreted to reflect hydrothermal fluid flow principally in a horizontal direction during ore deposition. Quartz vein-filling, accompanied by chlorite, calcite, rhodonite, and adularia, is widest in a vertical interval approximately 500 to 1000 meters below the original surface. Pyrite is widely distributed, but silver minerals, electrum, and base-metal sulfides are restricted to the upper portion of the vertical interval of veining in a zone termed the ore horizon. Fluid inclusion studies of quartz from the Cinco Senores vein indicate that ore deposited at an average temperature of 260 C from boiling fluids of apparent salinities ranging from 0.15 to 0.3 m/sub NaCl/ equivalent. The greater apparent salinities probably reflect dissolved gases as well as chloride salts. Correlation of Ag:Au ratios in deposited vein with ice-melting temperatures in fluid inclusions suggests that evolution of ore fluids in space was accompanied by both increase in deposited Ag:Au ratios and decline in fluid solute concentration. Correlation of ice-melting temperatures with paragenetic age of associated quartz suggests that vein-depositing hydrothermal fluids evolved in both space and time from relatively concentrated to dilute conditions.

  5. Structural evolution of a quartz sillimanite vein and nodule complex in a late-to post-tectonic leucogranite, Western Adirondack Highlands, New York

    NASA Astrophysics Data System (ADS)

    McLelland, James; Goldstein, Arthur; Cunningham, Betsy; Olson, Christopher; Orrell, Suzanne

    2002-07-01

    Quartz-sillimanite veins and nodules within the carapace of a late- to post- tectonic leucogranite crosscut one another as well as calcsilicate schlieren. These relationships document a fracture-related and hydrothermal origin of the vein and nodule complex. Two dominant orientations (N50E, N20E) are observed with the former being the oldest and most deformed. Both of these sets have undergone deformation, including boudinage of veins to produce nodules. Zircon geochronology fixes the emplacement age of the leucogranite at 1035.1±3.8 Ma and late crosscutting pegmatites at 1034±10 Ma, hence the vein-nodule complex must fall within this interval. Late dikes of leucogranite truncate the complex and document the continued presence of magma during vein-nodule formation. Anisotropy of magnetic susceptibility (AMS) in the leucogranite carapace reveals an approximately horizontal flow direction, within a plane striking N49E and dipping moderately to the northwest. In this regime, quartz-sillimanite veins formed initially as tension fractures in subvertical NNE orientations either as a result of high fluid pressures or rapid sinistral shear along the N50E contact. Progressive sinistral shear rotated the veins counterclockwise causing buckling followed by boudinage and rotation of fragments into near parallelism with the N50E contact. Strain was accommodated by slip between crystals and melt migration with an estimated melt fraction of at least 30%. Multiple episodes of fracturing and vein formation appear to have occurred. Final deformation of the carapace and the vein-nodule complex is envisioned as a flattening against the contact, perhaps as a result of pluton inflation. Melt was still present after this event as evidenced by post-vein granite and pegmatite dikes, commonly with sinistral shear along the dike margin.

  6. Brittle-viscous deformation of vein quartz under fluid-rich low greenschist facies conditions

    NASA Astrophysics Data System (ADS)

    Kjøll, H. J.; Viola, G.; Menegon, L.; Sørensen, B. E.

    2015-01-01

    A coarse grained, statically crystallized quartz vein, embedded in a phyllonitic matrix, was studied by EBSD and optical microscopy to gain insights into the processes of strain localization in quartz deformed under low-grade conditions, broadly coincident with the frictional-viscous transition. The vein is from a high strain zone at the front of the Porsa Imbricate Stack in the Paleoproterozoic Repparfjord Tectonic Window in northern Norway. The vein was deformed under lower greenschist facies conditions during deformation along a large out-of-sequence phyllonitic thrust of Caledonian age. The host phyllonite formed at the expense of metabasalt wherein feldspar broke down to form interconnected layers of fine, synkinematic phyllosilicates. In the mechanically weak framework of the phyllonite, the studied quartz vein acted as a relatively rigid body deforming mainly by coaxial strain. Viscous deformation was initially accommodated by basal ⟨a⟩ slip of quartz during the development of a mesoscopic pervasive extensional crenulation cleavage. Under the prevailing boundary conditions, however, dislocation glide-accommodated deformation of quartz resulted inefficient and led to dislocation tangling and strain hardening of the vein. In response to hardening, to the progressive increase of fluid pressure and the increasing competence contrast between the vein and the weak foliated host phyllonite, quartz crystals began to deform frictionally along specific, optimally oriented lattice planes, creating microgouges along microfractures. These were, however, rapidly sealed by nucleation of new grains as transiently over pressured fluids penetrated the deforming system. The new nucleated grains grew initially by solution-precipitation and later by grain boundary migration. Due to the random initial orientation of the vein crystals, strain was accommodated differently in the individual crystals, leading to the development of remarkably different microstructures. Crystals

  7. Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian; Fredriksson, Kurt; Goetzinger, Michael; Reimold, Wolf Uwe

    1989-01-01

    Quartz pebbles from the Roter Kamm impact crater (the Namib Desert, SWA/Namibia) were examined for evidence of impact-induced hydrothermal activity, using results from microprobe analyses, neutron activation analyses, transmission IR spectroscopy, and X-ray diffractometry. It was found that the pebbles consisted of pure quartz, which contains three different types of fluid inclusions. These were identified as primary inclusions (5-10 microns) that record the formation conditions of the quartz, very small (less than 1 micron) secondary inclusions associated with the grain boundaries, and late inclusions of irregular size. It is concluded that the quartz and the primary inclusions may provide evidence for a postimpact phase of extensive hydrothermal activity, generated by the residual heat from the kinetic energy of the impact.

  8. The nature of faults and hydrothermal veins in corehole SB-15-D, The Geysers Steam Field, California

    SciTech Connect

    Hulen, J.B.; Nielson, D.L.

    1995-12-31

    Porosity in The Geysers Coring Project corehole SB-15-D is concentrated along vuggy, steeply-dipping, hydrothermal calcite-quartz {plus_minus} adularia veins. There is little difference in the texture and abundance of these veins between the upper two thirds of the core, interpreted as caprock, and the lower two-thirds, in which two, vein-controlled, fluid-loss zones (probable steam entries) were encountered. However, vugs in the caprock veins are locally choked with mixed-layer clay, whereas those in the deeper steam-reservoir veins generally lack this clay but contain calc-silicate minerals. Steeply-dipping, concordant faults concentrated in argillite throughout the core show predominantly strike-slip displacement. Although movement was predominantly along argillites, the lithology appears to have deformed in a ductile manner, and porosity development was minimal. High-angle dilational fractures were developed contemporaneously in the graywackes. These fractures in the graywacke were only partially filled by secondary minerals, and are potential steam conduits in the vapor-dominated geothermal system.

  9. Brittle-viscous deformation of vein quartz under fluid-rich low greenschist facies conditions

    NASA Astrophysics Data System (ADS)

    Jørgen Kjøll, Hans; Viola, Giulio; Menegon, Luca; Sørensen, Bjørn

    2015-04-01

    A coarse grained, statically crystallized quartz vein with a random CPO, embedded in a phyllonitic matrix, was studied by optical microscopy, SEM imaging and EBSD to gain insights into the processes of strain localization in quartz deformed under low greenschist facies conditions at the frictional-viscous transition. The vein is located in a high strain zone at the front of an imbricate stack of Caledonian age along the northwesternmost edge of the Repparfjord Tectonic Window in northern Norway. The vein was deformed within the Nussirjavrri Fault Zone (NFZ), an out-of-sequence thrust with a phyllonitic core characterized by a ramp-flat-ramp geometry, NNW plunging stretching lineations and top-to-the SSE thrusting kinematics. Deformation conditions are typical of the frictional-viscous transition. The phyllonitic core formed at the expense of metabasalt wherein feldspar broke down to form interconnected layers of fine, synkinematic phyllosilicates. In the mechanically weak framework of the phyllonite, the studied quartz vein acted as a relatively rigid body deforming mainly by coaxial strain. Viscous deformation, related to the development of a mesoscopic pervasive extensional crenulation cleavage, was accommodated within the vein initially by basal slip of suitably oriented quartz crystals, which produced e.g. undulose extinction, extinction bands and bulging grain boundaries. In the case of misoriented quartz crystals, however, glide-accommodated dislocation creep resulted soon inefficient and led to localized dislocation tangling and strain hardening. In response to 1) hardening, 2) progressive increase of fluid pressure within the actively deforming vein and 3) increasing competence contrast between the vein and the surrounding weak, foliated phyllonitic fault core, quartz crystals began to deform frictionally along specific lattice planes oriented optimally with respect to the imposed stress field. Microfaulting generated small volumes of gouge along

  10. Genesis of Syntectonic Hydrothermal Veins in the Igneous Rock of Teschenite Association (Outer Western Carpathians, Czech Republic): Growth Mechanism and Origin of Fluids

    NASA Astrophysics Data System (ADS)

    Urubek, Tomáš; Dolníček, Zdeněk; Kropáč, Kamil

    2015-01-01

    Hydrothermal mineralization hosted by the Lower Cretaceous igneous rock of the teschenite association at Jasenice (Silesian Unit, Flysch Belt, Outer Western Carpathians) occurs in two morphological types - irregular vein filled by granular calcite and regular composite vein formed by both fibrous and granular calcite and minor chlorite, quartz, and pyrite. Crosscutting evidence indicates that the granular veins are younger than the composite vein. The composite vein was formed by two mechanisms at different times. The arrangement of solid inclusions in the marginal fibrous zone suggests an episodic growth by the crack-seal mechanism during syntectonic deformation which was at least partially driven by tectonic suction pump during some stages of the Alpine Orogeny. Both the central part of the composite vein and monomineral veins developed in a brittle regime. In these cases, the textures of vein suggest the flow of fluids along an open fracture. The parent fluids of both types of vein are characterized by low temperatures (Th=66-163 °C), low salinities (0.4 to 3.4 wt. % NaCl eq.), low content of strong REE-complexing ligands, and δ18O and δ13C ranges of + 0.2/+12.5 %. SMOW and -11.8/-14.1 %. PDB, respectively. The parent fluids are interpreted as the results of mixing of residual seawater and diagenetic waters produced by dewatering of clay minerals in the associ-ated flysch sediments. The flow of fluids was controlled by tectonic deformation of the host rock.

  11. Permeability evolution in quartz fault gouges under hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Giger, Silvio B.; Tenthorey, Eric; Cox, Stephen F.; Fitz Gerald, John D.

    2007-07-01

    The permeability (k) of fine-grained quartz aggregates were measured in situ during hot pressing (HPing) experiments to explore the evolution of fluid transport properties of fault zones during the interseismic period. Experiments were conducted at temperatures of 150°C and between 700 and 850°C, with confining and pore water pressures of 250 and 150 MPa, respectively. Significant permeability reduction was observed between 700 and 850°C, with permeability reduction rates (r = (1/t) ln (kto/kt)), ranging from approximately 6 × 10-5 s-1 at 700°C to a maximum of approximately 7.4 × 10-4 s-1 at 850°C. Permeability decreased exponentially with time, and the permeability reduction rate increased with increasing temperature, increasing differential stress, and decreasing grain size. Analysis of the permeability-porosity relationships indicates that permeability in the simulated gouge at high temperature shuts off at a critical porosity of 0.045 ± 0.004. The presence of microstructures, such as grain interpenetration, grain shape truncation, arrays of fluid inclusions, and development of quartz overgrowths on grains, indicate that k reduction was controlled by dissolution-precipitation creep processes. Extrapolation of the permeability reduction rates, measured in this study, to temperatures typical of the continental seismogenic regime highlights the strongly time-dependent nature of permeability in natural fault wear products at depths of nucleation of major earthquakes. Within the recurrence time of large earthquakes, quartz-rich fault zones in the fluid-active midcrustal to lower continental crustal regimes can evolve from high-permeability conduits to low-permeability seals. Episodic changes in the fluid transport properties of faults during the interseismic period are likely to impact on the pore pressure evolution of fault wear products.

  12. Cyclical Stress Field Switching and (Total?) Relief of Fault Shear Stress Recorded in Quartz Vein Systems Hosted by Proterozoic Strike-Slip Faults, Mt Isa, Australia

    NASA Astrophysics Data System (ADS)

    Sibson, R. H.; Begbie, M. J.; Ghisetti, F. C.; Blenkinsop, T. G.

    2003-12-01

    slip increments. A preliminary interpretation is that the differently oriented systematic vein-sets reflect changing orientations of the local stress field at different stages of the earthquake stress cycle. Minimum compressional stress oblique to the fault through the interseismic interval alternates with minimum compression oriented subperpendicular to the fault immediately postfailure, suggesting that each slip episode was accompanied by near-total relief of shear stress along the fault. The presence of amethystine quartz, open-space filling textures, and calcite-quartz intergrowths in the vein sets are consistent with hydrothermal precipitation occurring within 1-2 km of the former ground surface. Consequently, it is not yet clear whether these extensive vein systems developed under hydrostatic or overpresssured fluid conditions.

  13. Tectonic conditions of hydrothermal polymetallic vein-type mineralization, Sainte Marie-aux-Mines, France

    NASA Astrophysics Data System (ADS)

    Hafeznia, Y.; Bourlange, S.; Ohnenstetter, M.

    2012-04-01

    The Sainte-Marie-aux-Mines (SMM) mines host one of the most famous and oldest silver deposits in Europe. The SMM district is located in the central part of the Vosges mountains, France, within gneiss and granites of the Moldanubian zone. The SMM district includes the Neuenberg E-W vein-type Cu-Ag-As/Pb-Zn deposit and the Altenberg N-S vein-type Pb-Zn-Ag deposit. Deposition of the SMM hydrothermal mineralization occurred under a brittle tectonic regime that might be connected to neo-Variscan and/or post-Variscan tectonics, in a similar way as the polymetallic vein deposits of the Black Forest, Germany. A structural study was done in the Neuenberg area, in the vicinity of the Saint-Jacques vein, and within the Gabe Gottes mine, considering the orientation, extent, chronology and density of faults as well as the nature of the infilling minerals. In the Gabe-Gottes mine, the Saint-Jacques vein comprises multiple successive, sub-parallel subvertical veinlets with gangue minerals, mostly carbonates and quartz, and metal-bearing phases, sulfides and sulfosalts. The veinlets are 2 to 50 cm thick and strike N80° to N110°, the earlier veins slightly dipping towards the north, and the latest one, to the south. Seven systems of faults were identified, which may be classified into three major groups formed respectively before, during and after the main stage of ore deposition: a) Pre-mineralization faults - These consist of sinistral NE-SW strike-slip faults, and NW-SE and NE-SW steeply dipping normal faults. These could be related to Carboniferous events considering their relationships with the granitoid intrusives present in the mine area (Brézouard leucogranite ~329 Ma), and the extensional tectonics developed during exhumation processes. b) Faults associated with the main ore-deposition - These faults could be related to late-Hercynian processes from compressional to extensional tectonic regimes. Mineralization controlling faults consist of dextral and sinistral E

  14. Anomalous quartz from the Roter Kamm impact crater, Namibia: Evidence for post-impact hydrothermal activity

    SciTech Connect

    Koeberl, C. Univ. of Vienna ); Fredriksson, K. ); Goetzinger, M. ); Reimold, W.U. )

    1989-08-01

    Centimeter-sized quartz pebbles have been found on the rim of the Roter Kamm impact crater. The Roter Kamm crater has a diameter of about 2.5 km and is situated in the Namib Desert, SWA/Namibia. Because of the sand coverage, impact products are exposed exclusively in the form of ejecta on the crater rim. The quartz pebbles were found close to the main deposits of the impact breccias and show signs of wind abrasion. Thin sections revealed that the pebbles consist of individual quartz domains that are up to 1 mm in size. Under crossed nicols (polarized light), all individual domains show extinction almost simultaneously within {plus minus}2{degree}, which is a rare phenomenon. Microprobe studies, neutron activation analyses, and X-ray diffractometry confirmed that the material consists of pure quartz. The quartz contains three different types of fluid inclusions: primary inclusions that record the formation conditions of the quartz, very small (<1 {mu}m) secondary inclusions associated with the grain boundaries, and late inclusions of irregular size. Freezing point depression measurements of the primary inclusions indicate fluid salinities between 18.3 and 19.6 wt% NaCl. Homogenization temperatures (T{sub h}) for the primary inclusions range from 165 to 250{degree}C. The quartz and the primary inclusions may provide evidence for a post-impact phase of extensive hydrothermal activity, generated by the residual heat from the kinetic energy of the impact.

  15. Tectonic Evolution of Chingshui Geothermal Field Inferred from Evidence of Quartz and Calcite Veins

    NASA Astrophysics Data System (ADS)

    Lu, Y. C.; Song, S. R.; Wang, P. L.; Liu, C. M.; Yeh, E. C.

    2014-12-01

    The Chingshui geothermal field is located in the valley of Chingshui stream, where is about 27 km SW of Ilan, northeastern Taiwan. It is a tectonically complex area occurred by the Philippine Plate subducting beneath the Eurasian plate in the south with Okinawa Trough opening in the Ilan Plain. Owing to complicated geological structure, the heat source of Chingshui geothermal field is still controversial. For understanding hot fluid sources and tectonic evolution, this study focuses on field survey of veins and scaling in the Chingshui geothermal field, and the results inferred from the data of SEM, XRD, carbon and oxygen isotope, and Uranium-thorium dating. The Chingshui hot fluid contains both high concentrations of SiO­2 and HCO3-, therefore, temperature and pressure both drop when the hot fluids inject into shallower fractures, and calcite and quartz both could be precipitated with competition or simultaneously. In Chilukeng River, many euhedral quartz crystals occurred in large damage zone of Xioananao fault that indicated the temperature drop played the dominated role when the hot fluids injected into the shallow. It inferred that the quartz crystal precipitated under compression stress, evidenced by the Xioananao thrust fault with no surface rupture. Whiles, there are gouges in normal fault with abundant calcite or calcite with quartz veins cropped out in the confluence of Chingshui River and Chilukeng River. The results indicate that those veins occurred in more recent period by U-Th dating data, because of degassing CO2 occurred in open fractures by normal faulting or the stress changing from compression to extension. The standard oxygen isotopes range from 1.29 to 20.73 permil of SMOW and the clumped isotope of Δ47 outcrop is 0.385 in calcite veins, suggest that the highest temperature of thermal fulids with calcite precipitations is 222℃±9℃ by calibrated equation of Passey and Henkes 2012. Meanwhile, it also indicates that the oxygen isotope of

  16. Mass transfer during wall-rock alteration: An example from a quartz-graphite vein, Black Hills, South Dakota

    NASA Astrophysics Data System (ADS)

    Galbreath, K. C.; Duke, E. F.; Papike, J. J.; Laul, J. C.

    1988-07-01

    Mass transfer and fluid-rock interaction have been evaluated along two sample traverses in low-sillimanite grade quartz-mica schist adjacent to a synmetamorphic quartz-graphite vein in the southern Black Hills, South Dakota. In an ~ 17 cm halo between apparently unaltered schist and the vein contact is an outer zone of cryptic alteration and three inner zones of visible alteration. The cryptic zone consists of the original prograde metamorphic mineral assemblage (quartz + biotite ± muscovite + plagioclase + microcline) plus anomalously high amounts of tourmaline. The outermost visible zone contains abundant graphite. The second visible zone is defined by intensive bleaching of the schist. The innermost visible zone, immediately adjacent to the vein, is tourmaline + quartz + plagioclase + limonite + graphite. The vein is composed almost entirely of quartz, but also contains trace amounts of graphite. Mass balance calculations indicate that Al was essentially inert. The predominant chemical changes during wall-rock alteration were addition of B and C from the vein-forming fluid along with loss of K from the wall rocks, corresponding to precipitation of tourmaline and graphite, and the progressive destruction of microcline, biotite, and muscovite toward the vein. In addition, the elements V, Cr, Cu, Zn, Pb, As, Sb, W, and Au were introduced into the country rock, whereas Si, Rb, Ba, and Cs were removed. On the basis of a constant Al reference frame, calculations indicate a net volume loss of 21-34% within one centimeter of the vein with little or no volume loss further from the vein. Fluid-rock interaction modeling suggests that between one and four equivalent masses of fluid interacted chemically with the most altered mineral assemblages. In addition, greater than one equivalent mass of reactive fluid penetrated to distances of at least 5 cm from the vein contact.

  17. Hydrothermal alteration in the Bosumtwi impact structure: Evidence from 2M1-muscovite, alteration veins, and fracture fillings

    NASA Astrophysics Data System (ADS)

    Petersen, Michael T.; Newsom, Horton E.; Nelson, Melissa J.; Moore, Duane M.

    Drill-core samples from the Bosumtwi impact structure (1.07 Myr old and 10.5 km in diameter) in Ghana exhibit mineralogical evidence for post-impact hydrothermal alteration. Nine samples of drill core obtained through the 2004 International Continental Scientific Drilling Project (ICDP) were studied, including an uppermost fallback layer overlying impactite breccias, and partly deformed massive meta-graywacke bedrock. The petrographic study revealed alteration veins containing secondary sericitic muscovite (comparable to 2M1-muscovite) crosscutting original bedding in meta-graywacke and forming a matrix between clasts in impactite breccias. X-ray diffraction (XRD) shows that these impactite samples are rich in 2M1-muscovite, consistent with post-impact fluid deposition and alteration. Optical analysis indicates the presence of a pre-impact stratiform chlorite in meta-graywacke samples and a secondary alteration chlorite occurring in all samples. Secondary illite was detected in upper impactites of drill core LB-08A and samples containing accretionary lapilli. The lower temperature constraint for the hydrothermal event is given by 2M1-muscovite, secondary chlorite, and illite, all of which form at temperatures greater than 280 °C. An absence of recrystallization of quartz and feldspar indicates an upper temperature constraint below 900 °C. The presence of alteration materials associated with fractures and veins in the uppermost impactites of drill cores LB-07A and LB-08A indicates that a post-impact hydrothermal system was present in and adjacent to the central uplift portion of the Bosumtwi impact structure. A sample containing accretionary lapilli obtained from drill core LB-05A exhibits limited evidence that hydrothermal processes were more widespread within the impactites on the crater floor.

  18. Palaeoseismic events recorded in Archaean gold-quartz vein networks, Val d'Or, Abitibi, Quebec, Canada

    NASA Astrophysics Data System (ADS)

    Boullier, Anne-Marie; Robert, François

    1992-02-01

    Archaean gold-quartz vein deposits are commonly hosted in high-angle reverse shear zones and are interpreted to have formed in a regime of horizontal compression and high fluid pressure environment. This paper presents the results of a combined structural and fluid inclusion study on three gold-quartz vein deposits of the Val d'Or area (Abitibi, Quebec) consisting of subhorizontal extensional veins and E-W steeply dipping shear veins. Crack-seal structures, tourmaline fibres, stretched quartz crystals and open-space filling textures indicate that the subhorizontal veins formed by hydraulic fracturing under supralithostatic fluid pressure. CO 2-rich and H 2O + NaCl fluid inclusions, interpreted as two coexisting immiscible fluids, occur typically in microcracks of different orientations interpreted to have formed in the σ1- σ2 plane. Horizontal CO 2-rich fluid inclusion planes are contemporaneous with the opening of these veins (σ 3 vertical). Vertical H 2O + NaCl fluid inclusion planes, as well as some microstructures, such as deformed minerals, indicate that the same extensional veins have experienced episodic vertical shortening (σ 3 horizontal) alternating with the opening events. Deformation and slip/opening also occurred in shear veins in which preferred orientation of fluid inclusion planes is not clear, except that the H 2O + NaCl fluid inclusion planes tend to be oriented at high angles to the slip direction. The successive opening and collapse events in subhorizontal extensional veins are correlated with deformation and slip/opening events in shear veins, respectively, and are attributed to cyclic fluid pressure fluctuations in the system. They are thus consistent with the fault-valve model: sudden drop in fluid pressure from supralithostatic to lower values induces fluid unmixing and occurs immediately post-failure following seismic rupturing along the shear zone. Sealing of the shear veins allows the fluid pressure to build up again and the

  19. Intensity of quartz cathodoluminescence and trace-element content in quartz from the porphyry copper deposit at Butte, Montana

    USGS Publications Warehouse

    Rusk, B.G.; Reed, M.H.; Dilles, J.H.; Kent, A.J.R.

    2006-01-01

    Textures of hydrothermal quartz revealed by cathodoluminescence using a scanning electron microscope (SEM-CL) reflect the physical and chemical environment of quartz formation. Variations in intensity of SEM-CL can be used to distinguish among quartz from superimposed mineralization events in a single vein. In this study, we present a technique to quantify the cathodoluminescent intensity of quartz within individual and among multiple samples to relate luminescence intensity to specific mineralizing events. This technique has been applied to plutonic quartz and three generations of hydrothermal veins at the porphyry copper deposit in Butte, Montana. Analyzed veins include early quartz-molybdenite veins with potassic alteration, pyrite-quartz veins with sericitic alteration, and Main Stage veins with intense sericitic alteration. CL intensity of quartz is diagnostic of each mineralizing event and can be used to fingerprint quartz and its fluid inclusions, isotopes, trace elements, etc., from specific mineralizing episodes. Furthermore, CL intensity increases proportional to temperature of quartz formation, such that plutonic quartz from the Butte quartz monzonite (BQM) that crystallized at temperatures near 750 ??C luminesces with the highest intensity, whereas quartz that precipitated at ???250 ??C in Main Stage veins luminesces with the least intensity. Trace-element analyses via electron microprobe and laser ablation-ICP-MS indicate that plutonic quartz and each generation of hydrothermal quartz from Butte is dominated by characteristic trace amounts of Al, P, Ti, and Fe. Thus, in addition to CL intensity, each generation of quartz can be distinguished based on its unique trace-element content. Aluminum is generally the most abundant element in all generations of quartz, typically between 50 and 200 ppm, but low-temperature, Main Stage quartz containing 400 to 3600 ppm Al is enriched by an order of magnitude relative to all other quartz generations. Phosphorous

  20. Alteration and fluid flow around a sulfide-carbonate-quartz vein, Lucky Friday mine, Northern Idaho

    SciTech Connect

    Gitlin, E.C.

    1985-01-01

    Wall rocks at the Lucky Friday mine, Coeur d'Alene district, Idaho, contain a >500m wide zone about a steeply dipping Pb-Zn-Ag vein. This zone has experienced local conditions distinct from the regional metamorphism of the quartzite + argillite host rock. Within the district, the host rock (Precambrian Revett Formation) has undergone low grade metamorphism and contains varying proportions of quartz, phengitic muscovite, detrital alkali feldspar, magnetite, hematite, ilmenite, rutile, zircon, tourmaline, +/- calcite, +/- ankeritic dolomite. In contrast, the Lucky Friday wall rocks lack feldspar and Fe-bearing oxides, and contain Fe-poor muscovite and up to 40% carbonate: siderite, ankerite, and/or calcite. A comparison of district-wide Revett rocks with Lucky Friday wall rocks suggests that the wall rocks have undergone localized dephengitization with concomitant Fe-enrichment in the carbonates and Fe-depletion of the oxides. Pertinent metamorphic reactions consume CO/sub 2/ and liberate H/sub 2/O. Fluid inclusions from the vein and wall rock stringers have homogenization temperatures from approx. =200/sup 0/ to <375/sup 0/C, but they define no temperature gradient. With few exceptions, compositions of the carbonates are identical throughout the altered wall rock. These observations suggest that the carbonate subzone contacts are not isograds but isofluxes: the loci of equivalent fluid/reactant mineral ratio. The disposition of isofluxes around a dominant fluid channelway, i.e. the vein, affords an opportunity to interpret fluid flow pathways during low temperatures metamorphism.

  1. Three sets of fine extinction bands in a tectonically deformed vein-quartz single crystal

    NASA Astrophysics Data System (ADS)

    Derez, Tine; Van der Donck, Tom; Pennock, Gill; Drury, Martyn; Sintubin, Manuel

    2014-05-01

    Intracrystalline fine extinction bands (FEBs) in quartz, are narrow (less than 5µm thick), planar microstructures with a misorientation up to 5° with respect to the host crystal, occurring in closely spaced sets (spacing of 4-5μm). FEBs have been commonly attributed to a large range of brittle and/or crystal-plastic mechanisms, revealing considerable disagreement on the responsible crystal-plastic slip systems and the ambient conditions. Another question that arises, is whether or not the FEBs rotate from a basal plane orientation to orientations ranging between the basal and prism planes. Usually only one set of FEBs occurs in a single crystal, though two sets are observed, in particular with increasing strain. Tentatively, a maximum of two sets of sub-basal FEBs has been postulated to develop in a single quartz crystal in a tectonic context. However, we identified several crystals in naturally deformed vein-quartz containing three sets of FEBs. The vein-quartz has been deformed under sub-greenschist metamorphic conditions, during the late Palaeozoic Variscan orogeny, in the High-Ardenne slate belt (Belgium). The vein-quartz has been subjected to bulging dynamic recrystallisation and shows a high degree of undulatory extinction, abundant subgrains and wide extinction bands sub-parallel to the c-axis. We attempted to characterise these three sets of FEBs by means of light microscopy, EBSD-OIM and universal stage microscopy. In both cases studied the c-axis is inclined less than 8° with respect to the thin-section plane. The different sets of FEBs show a consistent orientation with respect to the c-axis. One set of FEBs deviates maximum 10° from the basal plane. The other two sets deviate between 15 and 35° from a basal plane orientation. Corresponding FEBs, at the same angle with respect to the c-axis, have similar morphologies. In relative EBSD orientation maps FEBs show a maximum misorientation of 3°, and have a lower pattern quality than the host crystal

  2. Colorado quartz: occurrence and discovery

    USGS Publications Warehouse

    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

  3. In situ 14C depth profile of subsurface vein quartz samples from Macraes Flat New Zealand

    NASA Astrophysics Data System (ADS)

    Kim, K. J.; Lal, D.; Englert, P. A. J.; Southon, J.

    2007-06-01

    We present results of measurements of cosmogenic in situ 14C produced in a quartz vein from Macraes Flat, East Otago, New Zealand, where concentrations of in situ produced 10Be and 26Al were previously studied by Kim and Englert [Earth Planet. Sci. Lett. 223 (2004) 113]. 14C was extracted from the quartz samples up to depths of 400 g cm-2 using a low temperature wet extraction method [D. Lal, A.J.T. Jull, Nucl. Instr. and Meth. B 92 (1994) 291]. Based on the results for 10Be and 26Al, we expected that the 14C activity in the samples would be at saturation levels, in equilibrium with erosion. The surface exposure age of this site was found to be about 25 000 years using 10Be and 26Al at the surface, with a surface erosion rate of at least 10-3 cm/y [K.J. Kim, P.A.J. Englert, Earth Planet. Sci. Lett. 223 (2004) 113]. The measured 14C activities were compared with those expected from spallation of Si and O in quartz by energetic neutrons and fast muons, and from capture of negative muons in O in quartz [B. Heisinger, A.J.T. Jull, D. Lal, P. Kubik, S. Ivy-Ochs, K. Knie, E. Nolte, Earth Planet. Sci. Lett. 200 (2002) 357; B. Heisinger, D. Lal, A.J.T. Jull, P. Kubik, S. Ivy-Ochs, S. Neumaier, K. Knie, V. Lazarev, E. Nolte, Earth Planet. Sci. Lett. 200 (2002) 345]. Surprisingly, we found that the 14C activities were significantly greater than those expected, by factors of 2 3, especially in samples of depths <200 g cm-2. We suspect that the excess 14C probably resulted from capture of thermal neutrons in nitrogen present in the fluid inclusions in quartz. This study shows that great care has to be taken in measurements of in situ 14C in quartz, especially in samples exposed near sea level and greater depths, where rates of spallation produced 14C are low.

  4. Mass transfer during wall-rock alteration: An example from a quartz-graphite vein, Black Hills, South Dakota

    SciTech Connect

    Galbreath, K.C.; Duke, E.F.; Papike, J.J. ); Laul, J.C. )

    1988-07-01

    Mass transfer and fluid-rock interaction have been evaluated along two sample traverses in low-sillimanite grade quartz-mica schist adjacent to a synmetamorphic quartz-graphite vein in the southern Black Hills, South Dakota. In an {approximately}17 cm halo between apparently unaltered schist and the vein contact is an outer zone of cryptic alteration and three inner zones of visible alteration. The cryptic zone consists of the original prograde metamorphic mineral assemblage plus anomalously high amounts of tourmaline. The outermost visible zone contains abundant graphite. The second visible zone is defined by intensive bleaching of the schist. The innermost visible zone, immediately adjacent to the vein, is tourmaline + quartz + plagioclase + limonite + graphite. The vein is composed almost entirely of quartz, but also contains trace amounts of graphite. Mass balance calculations indicate that Al was essentially inert. The predominant chemical changes during wall-rock alteration were addition of B and C from the vein-forming fluid along with loss of K from the wall rocks, corresponding to precipitation of tourmaline and graphite, and the progressive destruction of microcline, biotite, and muscovite toward the vein. In addition, the elements V, Cr, Cu, Zn, Pb, As, Sb, W, and Au were introduced into the country rock, whereas Si, Rb, Ba, and Cs were removed. Fluid-rock interaction modeling suggests that between one and four equivalent masses of fluid interacted chemically with the most altered mineral assemblages. In addition, greater than one equivalent mass of reactive fluid penetrated to distances of at least 5 cm from the vein contact.

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

    NASA Astrophysics Data System (ADS)

    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

  6. Development of discrete aggregates of recrystallization along micro-shear zones in quartz ribbons during multistage ductile evolution of a quartz vein

    NASA Astrophysics Data System (ADS)

    Ceccato, Alberto; Pennacchioni, Giorgio; Bestmann, Michel

    2016-04-01

    The post-magmatic ductile deformation of the Rieserferner pluton (Eastern Alps) includes localized ductile shear zones exploiting a set of joint-filling quartz veins. These deformed veins show different stages of evolution, from coarse grained vein quartz to the fine grained recrystallized aggregates of ultramylonites, locally recorded in different domains of heterogeneously sheared veins. The microstructural evolution includes, with increasing strain: (i) Development of ribbon mylonites consisting of elongated grains, oblique to the shear zone boundary, derived from different quartz veins crystals. The individual ribbons have different crystallographic orientations and aspect ratios. (ii) Dismantling of ribbons along a fracture-like network of fine grained recrystallized quartz aggregates, that commonly represent micro-shear zones (μSZ). These discrete recrystallization zones are preferentially developed in ribbons whose crystallographic axis is oriented either parallel or normal to ribbon elongation. (iii) Extensive dynamic recrystallization to fine-grained (10-20 μm) aggregates leading to quartz ultramylonites. Typically ultramylonites show a layered texture with bands having different crystallographic preferred orientation (CPO) that probably reflect the original heterogeneity in crystallographic orientations of the vein. Electron backscattered diffraction analysis indicates that the μSZ within quartz ribbons are mainly parallel to {r} or {z} planes of the host grain, and the new grain inside μSZ show a weak CPO with their basal plane parallel to the μSZ boundary. There is no systematic relationships between the Dauphiné twinning and the μSZ. Misorientation analysis suggests that in the host grain dislocation creep is dominant on {m} slip system, whereas it is probably a minor mechanism within μSZ. Subgrains and low-angle boundaries (LAB) are heterogeneously developed at the border of the μSZ, and more commonly occur around the tips of

  7. Geology, Ore-microscopy and Fluid inclusion study on Auriferous Quartz Veins at the Gidami Gold Mine, Eastern Desert of Egypt

    NASA Astrophysics Data System (ADS)

    Abd El Monsef, Mohamed; Salem, Ibrahim; Slobodnik, Marek

    2013-04-01

    The gold deposits are represented by auriferous quartz veins and aplitic dykes that are cutting through granitic rocks. The main lode of gold is confined to two principal veins occupying fracture zones and fissures. The main auriferous vein is striking mainly NNW-SSE with dipping 85° NE, it extends up to 450 m with an average thickness 120 cm. The second vein is striking NW-SE and dipping 60° E, it extends for 150 m with an average thickness 35 cm. The gold bearing veins are made up of fine grained quartz that is always massive, milky-white with reddish or greenish tint. They commonly include vugs, some of them are occasionally filled with iron oxides, carbonate and clay minerals. Sometimes the quartz veins enclose remnants of altered wall rock materials as an indication for the metamorphic or syntectonic nature of the veins. Brecciation, comb layering, swelling and nodules manganese dendrites are usually detected. The microscopic examination for thin and polished sections of auriferous quartz veins revealed that quartz and calcite are the predominant minerals commonly associated with accessory minerals (fluorite, apatite, zircon, muscovite and sericite). Ore mineral assemblage is found as disseminated sulfide minerals (pyrite, sphalerite, chalcopyrite, molybdenite, pyrrhotite covellite, galena and pentlandite). Ilmenite and goethite are the main iron oxide mineral phases. Gold most commonly occurs as small inclusions within pyrite or goethite. Gold also occurs as tiny grains scattered within quartz vein (in close proximity to the sulfides) or as disseminated grains in the altered wall rocks. Hydrothermal alteration includes silicification, kaolinitization, sericitisation, carbonatisation confined to a delicate set of veins. Petrography and microthermometry of fluid inclusions revealed that the majority of inclusions are of primary/pseudosecondary nature that occur in clusters and along growth zones or along intra-granular planar trails (pseudosecondary

  8. Metamorphic origin of ore-forming fluids for orogenic gold-bearing quartz vein systems in the North American Cordillera: constraints from a reconnaissance study of δ15N, δD, and δ18O

    USGS Publications Warehouse

    Jia, Y.; Kerrich, R.; Goldfarb, R.

    2003-01-01

    The western North American Cordillera hosts a large number of gold-bearing quartz vein systems from the Mother Lode of southern California, through counterparts in British Columbia and southeastern Alaska, to the Klondike district in central Yukon. These vein systems are structurally controlled by major fault zones, which are often reactivated terrane-bounding sutures that formed in orogens built during accretion and subduction of terranes along the continental margin of North America. Mineralization ages span mid-Jurassic to early Tertiary and encompass much of the evolution ofthe Cordilleran orogen. Nitrogen contents and ??15N values of hydrothermal micas from veins are between 130 and 3,500 ppm and 1.7 to 5.5 per mil, respectively. These values are consistent with fluids derived from metamorphic dehydration reactions within the Phanerozoic accretion-subduction complexes, which have ??15N values of 1 to 6 per mil. The ??18O values of gold-bearing vein quartz from different locations in the Cordillera are between 14.6 and 22.2 per mil but are uniform for individual vein systems. The ??D values of hydrothermal micas are between -110 and -60 per mil. Ore fluids have calculated ??18O values of 8 to 16 per mil and ??D values of -65 to -10 per mil at an estimated temperature of 300??C; ??D values of ore fluids do not show any latitudinal control. These results indicate a deep crustal source for the ore-forming fluids, most likely of metamorphic origin. Low ??DH2O values of -120 to -130 per mil for a hydrous muscovite from the Sheba vein in the Klondike district reflect secondary exchange between recrystallizing mica and meteoric waters. Collectively, the N, H, and O isotope compositions of ore-related hydrothermal minerals indicate that the formation of these gold-bearing veins involved dilute, aqueous carbonic, and nitrogen-bearing fluids that were generated from metamorphic dehydration reactions at deep crustal levels. These data are not consistent with either mantle

  9. Recrystallization fabrics of sheared quartz veins with a strong pre-existing crystallographic preferred orientation from a seismogenic shear zone

    NASA Astrophysics Data System (ADS)

    Price, Nancy A.; Song, Won Joon; Johnson, Scott E.; Gerbi, Christopher C.; Beane, Rachel J.; West, David P.

    2016-07-01

    Microstructural investigations were carried out on quartz veins in schist, protomylonite, and mylonite samples from an ancient seismogenic strike-slip shear zone (Sandhill Corner shear zone, Norumbega fault system, Maine, USA). We interpret complexities in the microstructural record to show that: (1) pre-existing crystallographic preferred orientations (CPO) in the host rock may persist in the new CPO patterns of the shear zone and (2) the inner and outer parts of the shear zone followed diverging paths of fabric development. The host rocks bounding the shear zone contain asymmetrically-folded quartz veins with a strong CPO. These veins are increasingly deformed and recrystallized with proximity to the shear zone core. Matrix-accommodated rotation and recrystallization may position an inherited c-axis maximum in an orientation coincident with rhomb < a > or basal < a > slip. This inherited CPO likely persists in the shear zone fabric as a higher concentration of poles in one hemisphere of the c-axis pole figure, leading to asymmetric crossed girdle or paired maxima c-axis patterns about the foliation plane. Three observed quartz grain types indicate a general trend of localization with decreasing temperature: (1) large (> 100 μm), low aspect ratio (<~5) and (2) high aspect ratio (~ 5-20) grains overprinted by (3) smaller (<~80 μm), low aspect ratio (<~4) grains through subgrain rotation-dominated recrystallization. In the outer shear zone, subgrain rotation recrystallization led to a well-developed c-axis crossed girdle pattern. In the inner shear zone, the larger grains are completely overprinted by smaller grains, but the CPO patterns are relatively poorly developed and are associated with distinctively different misorientation angle histogram profiles ("flat" neighbor-pair profile with similar number fraction for angles from 10 to 90°). This may reflect the preferential activation of grain size sensitive deformation processes in the inner-most part of the

  10. Crystallochemical and structural evolution of tourmaline in auriferous quartz veins of the Iskel terrane prospect (western Hoggar, Tamanrasset, South Algeria)

    NASA Astrophysics Data System (ADS)

    Talbi, Mohamed; Chaouche, Ismahane; Fuchs, Yves

    2016-04-01

    A mylonite zone limits the Iskane Terrane tectonic unit (Western Hoggar). This zone is intruded by granitic units belonging to the Taourirt cycle. North -South and North East-South West trending auriferous quartz veins are hosted in the cataclased areas. Visible gold can be observed but gold is also present in sulfides (pyrite, chalcopyrite). Tourmaline is abundant in these veins. Mossbauer spectrometry as well as FTIR spectrometry shows that in some sectors tourmaline underwent an oxidation process posterior to its formation. The general structure of tourmaline studied, shows the coexistence of ferric iron Fe3+ with ferrous iron Fe2+ in the Y site. This represents a tourmaline "deprotonated". This oxidation induced a partial transformation of Fe2+ in Fe3+ that is charge compensated by a deshydroxylation of the central OH group. The relationship of the gold deposition with the oxidation of tourmaline is discussed. Key words: Tourmaline, oxidation, "deprotonation-deshydroxylation", sulfides, gold.

  11. Age and genesis of precious metals deposits, Buffalo Hump district, central Idaho: implications for depth of emplacement of quartz veins.

    USGS Publications Warehouse

    Lund, K.; Snee, L.W.; Evans, K.V.

    1986-01-01

    Three samples (metamorphic country rock, Idaho batholith granite, and auriferous quartz vein) were dated by the 40Ar/39Ar age spectrum technique. The lode deposits are Cretaceous (71 m.y.); their cooling histories and depths of emplacement, inferred from the age spectra, are evidence for the granite plutons and the lode deposits having been emplaced at the same 40-9 km depth and being genetically related. Thus, the Idaho batholith is not barren, and at least two precious-metal mineralizing events, Cretaceous and Eocene in age, occur in central Idaho. Class differences between the two ages of deposits, of style, alteration and mineralogy, are suggested. -G.J.N.

  12. Using vein fabric and fluid inclusion characteristics as an integrated proxy to constrain the relative timing of non cross-cutting, syn- to late-orogenic quartz vein generations

    NASA Astrophysics Data System (ADS)

    Jacques, Dominique; Muchez, Philippe; Sintubin, Manuel

    2014-05-01

    Research on ancient fluid systems mainly focuses on veins, because they offer the opportunity to combine macro- and microstructural data with geochemical data to gain insight into the P-T-X conditions present during veining. By applying such an integrated petrographic and microthermometric methodology to syn- to late-orogenic quartz veins in the Palaeozoic High-Ardenne slate belt (Belgium), we were able to define the relative timing and related P-T-X conditions of different quartz vein generations, despite of the absence of any mutual cross-cutting relationships in the field (Jacques et al., 2014). The different quartz vein generations represent the meso-scale brittle accommodation during fold initiation, amplification and locking. The presence of free polycrystal growth in cavities at a midcrustal depth, and fluid-assisted brecciation indicate that veining occurred under overpressured fluid conditions during the orogeny. Significant differences in crystal-plastic deformation microstructures and P-T trapping conditions indicate that the different processes accommodating folding occurred in a progressive manner along a retrograde deformation path. While vein quartz in an extrados vein and in the peripheral part of a lenticular, fault-accommodating vein shows moderate crystal-plastic deformation (e.g. bulging recrystallisation, deformation lamellae, shear bands), crystal-plastic deformation is relatively absent in the vein quartz of a saddle reef and the core of the lenticular vein (i.e. no to minor undulose extinction). Successive veining occurred from peak metamorphic conditions (ca. 300 ° C and 190 MPa), measured in the extrados vein, to lower P-T conditions in the periphery of the lenticular vein (ca. 275 ° C and 180 MPa), the late-orogenic saddle reef (ca. 245 ° C and 160 MPa) and the core of the lenticular vein (ca. 220 ° C and 150 MPa). The relative timing and accompanying decrease in P-T conditions of the different quartz vein generations reflect the

  13. Blue, complexly zoned, (Na,Mg,Fe,Li)-rich beryl from quartz-calcite veins in low-grade metamorphosed Fe-deposit Skály near Rýmařov, Czech Republic

    NASA Astrophysics Data System (ADS)

    Novák, Milan; Gadas, Petr; Filip, Jan; Vaculovič, Tomáš; Přikryl, Jan; Fojt, Bohuslav

    2011-10-01

    Syn-tectonic quartz-calcite veins containing blue beryl are enclosed in hematite > magnetite-rich portions of the low-grade metamorphosed Fe-deposit Skály near Rýmařov, Czech Republic. Aggregates of pale to deep blue beryl, up to 2 cm in diameter, are associated with euclase, clinochlore, hematite, albite and dravite. Complexly zoned beryl crystals consist of skeletal aggregates of beryl I randomly distributed within volumetrically dominant beryl II with narrow rims of beryl III. All types of beryl have similar contents of Na (0.32-0.49 apfu) and Mg (0.31-0.41 apfu) but variable contents of Fetot (0.05-0.34 apfu) and Al (1.20-1.62 apfu). The LA-ICP-MS study yielded elevated contents of Li, up 1,314 ppm (0.28 wt.% Li2O) in beryl I. The quartz-calcite veins represent an unusual type of low-T metamorphic-hydrothermal vein related to Fe-ore deposit characterized by single-stage fracturing and mobilization in a closed system at T~200-300°C and CO{3/2-} as a major complexing agent for the mobility of Be.

  14. Epidote-Bearing Veins in the State 2-14 Drill Hole: Implications for Hydrothermal Fluid Composition

    NASA Astrophysics Data System (ADS)

    Caruso, L. J.; Bird, D. K.; Cho, M.; Liou, J. G.

    1988-11-01

    Epidote-bearing veins in State 2-14 drill core from 900 to 2960 m depth were examined using backscattered electron microscopy and electron probe microanalysis to characterize the mineralogy, parageneses, texture, and composition of vein minerals. In order of decreasing abundance, minerals in epidote-bearing veins are pyrite, calcite, K-feldspar, quartz, anhydrite, hematite, chlorite, Fe-Cu-Zn sulfides, actinolite, titanite, and allanite. The downhole distribution of minerals in epidote-bearing veins (+ pyrite and quartz) varies as a function of depth and includes: (1) calcite above ˜2000 m, (2) K-feldspar between 1700 and 2745 m, (3) anhydrite between 2195 and 2745 m, (4) hematite ± sulfides above 2773 m, and (5) actinolite below ˜2890 m. Where present, K-feldspar was the first mineral to precipitate in veins followed by epidote. In all other veins, epidote was the earliest vein mineral to form. Calcite, quartz, anhydrite, hematite, and sulfides were paragenetically later. Compositional zoning, common in most vein epidotes, is typically symmetric with Al-rich cores and Fe3+ -rich rims. The minimum mole fraction of Ca2Fe3Si3O12(OH) (XPs) in vein epidotes decreases systematically with increasing depth from ˜0.33 at 906 m to ˜0.21 at 2900 m, and the maximum XPs at any given depth is greater than 0.33. Thermodynamic analyses of phase relations among vein-filling minerals and aqueous solutions at depths near 1867 m and 300°C indicate that the modern reservoir fluid in the Salton Sea geothermal system is in equilibrium with calcite + hematite + quartz + epidote (XPs = 0.33) ± anhydrite. The predicted fugacity of CO2 (˜14 bars) for the modern Salton Sea brine is in close agreement with the calculated value of fCO2 for the 1867 m production fluid. Theoretical phase diagrams in the system CaO-K2O-Fe2O3-Al2O3-SiO2-H2O-O2-S2-CO2 demonstrate that the mineralogies and mineral parageneses recorded hi epidote-bearing veins and the observed variations in Al-Fe3+ content of

  15. The gold content of some Archaean rocks and their possible relationship to epigenetic gold-quartz vein deposits

    NASA Astrophysics Data System (ADS)

    Meyer, M.; Saager, R.

    1985-10-01

    Gold mineralization in Archaean granite-greenstone environments, especially gold-quartz veins, contributes considerably to the world's gold production. The formation of epigenetic gold mineralization in greenstone belts is generally explained by the metamorphic secretion theory. This theory is based on the assumption that the source of the gold may be komatiitic or tholeiitic lavas, pyritic chemical or clastic sediments and even granitic rocks from which, as a result of regional metamorphic overprinting, gold was extracted and concentrated in suitable structures. It has been shown that in proposed potential source rocks, gold is predominantly associated with sulfide minerals and thus relatively easily accessible to secretion and reconstitution processes. A large number of various rock types originating from granite-greenstone terranes of the Kaapvaal and the Rhodesian cratons were geochemically investigated, and the following ranges for gold determined: volcanic rocks (komatiitic and tholeiitic): 0.1 372 ppb granitic rocks of the basement: 0.3 7.8 ppb iron-rich chemical sediments: 1.0 667 ppb Statistical treatment of the data reveals that volcanic rocks as well as iron-rich chemical sediments are favorable sources for epigenetic gold mineralization formed by metamorphic secretion, while the granitic rocks make less suitable primary gold sources. This finding explains the close spatial relationship which is common between gold-quartz veins and greenstone belts. The conspicuous abundance of epigenetic gold mineralization in the Archaean, however, is attributed to the unique geologic and metamorphic history of the granite-greenstone terranes.

  16. Structure, alteration, and geochemistry of the Charlotte quartz vein stockwork, Mt Charlotte gold mine, Kalgoorlie, Australia: time constraints, down-plunge zonation, and fluid source

    NASA Astrophysics Data System (ADS)

    Mueller, Andreas G.

    2015-02-01

    The Kalgoorlie district in the Archean Yilgarn Craton, Western Australia, comprises two world-class gold deposits: Mt Charlotte (144 t Au produced to 2013) in the northwest and the Golden Mile (1,670 t Au) in the southeast. Both occur in a folded greenschist-facies gabbro sill adjacent to the Golden Mile Fault (D2) in propylitic alteration associated with porphyry dikes. At Mt Charlotte, a shear array of fault-fill veins within the Golden Mile Fault indicates sinistral strike-slip during Golden Mile-type pyrite-telluride mineralization. The pipe-shaped Charlotte quartz vein stockwork, mined in bulk more than 1 km down plunge, is separated in time by barren D3 thrusts from Golden Mile mineralization and alteration, and occurs between two dextral strike-slip faults (D4). Movement on these faults generated an organized network of extension and shear fractures opened during the subsequent infiltration of high-pressure H2S-rich fluid at 2,655 ± 13 Ma (U-Pb xenotime). Gold was deposited during wall rock sulphidation in overlapping vein selvages zoned from deep albite-pyrrhotite (3 g/t Au) to upper muscovite-pyrite assemblages (5 g/t Au bulk grade). Chlorite and fluid inclusion thermometry indicate that this kilometre-scale zonation is due to fluid cooling from 410-440 °C at the base to 350-360 °C at the top of the orebody, while the greenstone terrane remained at 250 °C ambient temperature and at 300 MPa lithostatic pressure. The opened fractures filled with barren quartz and scheelite during the retrograde stage (300 °C) of the hydrothermal event. During fracture sealing, fluid flux was periodically restricted at the lower D3 thrust. Cycles of high and low up-flow, represented by juvenile H2O-CO2 and evolved H2O-CO2-CH4 fluid, respectively, are recorded by the REE and Sr isotope compositions of scheelite oscillatory zones. The temperature gradient measured in the vein stockwork points to a hot (>600 °C) fluid source 2-4 km below the mine workings, and several

  17. Direct measurement of asperity contact growth in quartz at hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Beeler, N. M.; Hickman, Stephen H.

    2015-05-01

    Earthquake recurrence requires interseismic fault restrengthening which results from solid-state deformation in room temperature friction and indentation experiments. In contrast, exhumed fault zones show solution-transport processes such as pressure solution, and contact overgrowths influence fault zone properties. In the absence of fluid flow, overgrowths are driven by gradients in surface curvature where material is dissolved, diffuses, and precipitates at the contact without convergence normal to the contact. To determine the rate of overgrowth for quartz, we conducted single-contact experiments in an externally heated pressure vessel. Convergence was continuously monitored using reflected light interferometry through a long-working-distance microscope. Contact normal force was constant with an initial effective normal stress of 1.7 MPa, temperature was between 350 and 530°C, and water pressure was constant at 150 MPa. Two control experiments were conducted: one dry at 425°C and one bimaterial (sapphire) at 425°C and 150 MPa water pressure. No contact growth or convergence was observed in the controls. For wet single-phase contacts, growth was initially rapid and then decreased with time. No convergence was observed. Fluid inclusions indicate that the contact is not uniformly wetted. The contact is bounded by small regions of high aperture, reflecting local free-face dissolution as the source for the overgrowth. The apparent activation energy is ~125 kJ/mol. Extrapolation predicts rates of contact area increase orders of magnitude faster than in dry, room temperature and hydrothermal friction experiments, suggesting that natural strength recovery near the base of the seismogenic zone could be dominated by contact overgrowth.

  18. Direct measurement of asperity contact growth in quartz at hydrothermal conditions

    USGS Publications Warehouse

    Beeler, Nicholas M.; Hickman, Stephen H.

    2015-01-01

    Earthquake recurrence requires interseismic fault restrengthening which results from solid state deformation in room-temperature friction and indentation experiments. In contrast exhumed fault zones show solution-transport processes such as pressure solution and contact overgrowths influence fault zone properties . In the absence of fluid flow, overgrowths are driven by gradients in surface curvature where material is dissolved, diffuses, and precipitates at the contact without convergence normal to the contact. To determine the rate of overgrowth for quartz, we conducted single contact experiments in an externally heated pressure vessel. Convergence was continuously monitored using reflected-light interferometry through a long-working-distance microscope. Contact normal force was constant with an initial effective normal stress of 1.7 MPa, temperature was between 350 and 530{degree sign}C, and water pressure was constant at 150 MPa. Two control experiments were conducted: one dry at 425{degree sign}C and one bi-material (sapphire) at 425{degree sign}C and 150 MPa water pressure. No contact growth or convergence was observed in the controls. For wet single-phase contacts, growth was initially rapid and then decreased with time. No convergence was observed. Fluid inclusions indicate that the contact is not uniformly wetted. The contact is bounded by small regions of high aperture, reflecting local free-face dissolution as the source for the overgrowth. The apparent activation energy is ~125 kJ/mol. Extrapolation predicts rates of contact area increase orders of magnitude faster than in dry, room-temperature and hydrothermal friction experiments, suggesting that natural strength recovery near the base of the seismogenic zone could be dominated by contact overgrowth.

  19. U-Pb-Th geochronology of monazite and zircon in albitite metasomatites of the Rožňava-Nadabula ore field (Western Carpathians, Slovakia): implications for the origin of hydrothermal polymetallic siderite veins

    NASA Astrophysics Data System (ADS)

    Hurai, V.; Paquette, J.-L.; Lexa, O.; Konečný, P.; Dianiška, I.

    2015-10-01

    Sodic metasomatites (albitites) occur around and within siderite veins in the southern part of the Gemeric tectonic unit of the Western Carpathians. Accessory minerals of the metasomatites represented by monazite, zircon, apatite, rutile, tourmaline and siderite are basically identical with the quartz-tourmaline stage of other siderite and stibnite veins of the tectonic unit. Statistical analysis of chemical Th-U(total)-Pb isochron method (CHIME) of monazite dating yielded Jurassic-Cretaceous ages subdivided into 3-4 modes, spreading over time interval between 78 and 185 Ma. In contrast, LA-ICPMS 206Pb/238U dating carried out on the same monazite grains revealed a narrow crystallization interval, showing ages of Th-poor cores with phengite inclusions identical within the error limit with Th-rich rims with cauliflower-like structure. The determined lower intercept at 139 ± 1 Ma overlapped the Vallanginian-Berriasian boundary, thus corroborating the model of formation of hydrothermal vein structures within an arcuate deformation front built up in the Variscan basement as a response to Early Cretaceous compression, folding and thrusting. In contrast, associated zircons are considerably older than the surrounding Early-Palaeozoic volcano-sedimentary rocks, showing Neoproterozoic ages. The zircon grains in albitite metasomatites are thus interpreted as fragments of Pan-African magmatic detritus incorporated in the vein structures by buoyant hydrothermal fluids.

  20. Towards the question of the movement of hydrothermal solutions: The case of the Schlema-Alberoda vein deposit

    NASA Astrophysics Data System (ADS)

    Naumov, G. B.; Vlasov, B. P.; Mironova, O. F.

    2014-09-01

    The paths of the movements of hydrothermal solutions are considered in the case of one of the world's largest uranium vein deposits, the Schlema-Alberoda, which was mined by the Soviet-German corporation Wismut JSC in the second half of the 20th century. Detailed geological exploration to a depth of 2 km was accompanied by specialized research, the results of which have remained practically unpublished due to confidentiality. The data obtained show that the region adjoining the largest fault was draining rather than ore-conducting. This circumstance specifies and supplements the current concept concerning the movement of hydrothermal fluids.

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

    NASA Astrophysics Data System (ADS)

    Kidder, S.; Avouac, J.-P.; Chan, Y.-C.

    2012-06-01

    The accuracy, reliability and best practices 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 Taiwan's Hsüehshan range. The spread of Ti concentrations of recrystallized grains in quartzite correlates with recrystallized grain size. Recrystallized quartz (grain size ~300 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. Vein emplacement and quartzite recrystallization are independently shown to have occurred at 250-350 °C and 300-410 °C respectively, lithostatic pressure ~5 kbar, and 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, Ti concentrations predicted by the Thomas et al. (2010) TitaniQ calibration are within error of Ti concentrations measured by SIMS. If fluid pressure is 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 temperatures as low as ~250 °C, however clarification of the relevant pressure term and further tests in rutile-present rocks are warranted.

  2. Hydrothermal Quartz Oxygen Isotope Ratios in Altered Post-Collapse Rhyolite at Sevenmile Hole, Grand Canyon of the Yellowstone River, Yellowstone National Park, WY

    NASA Astrophysics Data System (ADS)

    Phillips, A. R.; Larson, P. B.; John, D. A.; Pauley, B. M.

    2008-12-01

    The Grand Canyon of the Yellowstone River, Yellowstone National Park, Wyoming, displays regions of pervasively hydrothermally altered rock formed in the shallow, epithermal portions of a hydrothermal system. Hydrothermal fluid circulation causing the alteration is driven by magmatism related to the Yellowstone Caldera thermal anomaly. The protolith, the Tuff of Sulfur Creek, is a 480 ka high silica, low δ18O rhyolitic tuff that erupted after the Yellowstone caldera collapse at 640 ka. Incision of the canyon has exposed 350 vertical meters in the Sevenmile Hole vicinity. Hydrothermal mineralogy determined by standard XRD powder techniques and PIMA on over 90 samples shows both vertical and lateral variation. A vertical transition occurs from kaolinite at depths less than about 100 meters below the present day canyon rim, to illite in deeper exposures. This transition may correspond to a temperature of 150°C, based on a similar transition in the active Yellowstone hydrothermal system. A lateral variation of mineral assemblages in the altered tuff suggests temperatures that may range up to 330°C. Alteration was most likely caused by a liquid due to the presence of pyrite throughout. Local zones of suspected hydrothermal fluid upwelling correspond to the most intense silicification and highest temperature mineral assemblages. This alteration includes quartz + illite ± hyalophane, slawsonite, and buddingtonite. At similar depths outside inferred fluid upwelling zones, lower temperature assemblages are quartz + illite/smectite ± alunite and buddingtonite. At shallow depths, the lowest temperatures are suggested by the presence of quartz + kaolinite ± alunite and opal. Dickite, a kaolinite polymorph, may indicate locally higher temperatures in the shallow kaolinite zones. Oxygen isotope ratios of silica phases were measured for approximately 50 samples using laser fluorination techniques with an error of ±0.2‰. Hydrothermal quartz displays δ18O signatures more

  3. Scaling the 3-D Mohr circle and quantification of paleostress during fluid pressure fluctuation - Application to understand gold mineralization in quartz veins of Gadag (southern India)

    NASA Astrophysics Data System (ADS)

    Lahiri, Sivaji; Mamtani, Manish A.

    2016-07-01

    In this study, orientations of 157 quartz veins occurring in metabasalts of the Gadag region (Dharwar craton, southern India) are used to plot the 3-D Mohr stress circle, which provides information about relative stress/fluid pressure (Pf) conditions, as well as stress state during Pf fluctuation. To scale the 3-D Mohr circle, vein orientation data are integrated with (a) available estimates from fluid inclusions of highest recorded Pf (390 MPa) and lowest recorded Pf (50 MPa) and (b) intrinsic rupture criterion that empirically quantify rock properties. Based on the scaled 3-D Mohr circle, the absolute magnitudes of the three principal stresses are quantified for high and low Pf. Of 157 veins investigated here, 14 veins are identified as having favourable orientation for dilation at high as well as low Pf. These 14 veins have a mean strike of 150°, which is similar to the orientation of the gold-bearing quartz lodes reported in the region. The effective normal stress (σ‧n = σn-Pf) prevalent during dilation of fracture/fabric anisotropy with 150° strike is calculated to be -11.5 MPa at high Pf, and -1.0 MPa at low Pf. Thus, it is interpreted that in the Gadag region, a change in σ‧n of 10.5 MPa prevailed during Pf fluctuation and associated separation of gold from the fluid.

  4. A new LA-ICP-MS method for Ti-in-Quartz: Implications and application to HP rutile-quartz veins from the Czech Erzgebirge

    NASA Astrophysics Data System (ADS)

    Cruz-Uribe, A. M.; Mertz-Kraus, R.; Zack, T.; Feineman, M. D.; Woods, G.

    2014-12-01

    Experimental determination of the pressure and temperature controls on Ti solubility in quartz provide a calibration of the Ti-in-quartz (TitaniQ) geothermometer applicable to geologic conditions up to ~20 kbar (Thomas et al. (2010) Contrib Mineral Petrol 160, 743-759). One of the greatest limitations to analyzing Ti in metamorphic quartz by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is the lack of a suitable matrix-matched reference material. Typically LA-ICP-MS analyses of Ti in minerals use 49Ti as a normalizing mass because of an isobaric interference from 48Ca, which is present in most well characterized reference glasses, on 48Ti. The benefit of using a matrix-matched reference material to analyze Ti in quartz is the opportunity to use 48Ti (73.8 % abundance) as a normalizing mass, which results in an order of magnitude increase in signal strength compared to the less abundant isotope 49Ti (5.5 % abundance), thereby increasing the analytical precision. Here we characterize Ti-bearing SiO2 glasses from Heraeus Quarzglas and natural quartz grains from the Bishop Tuff by cathodoluminescence (CL) imaging, electron probe microanalysis (EPMA), and LA-ICP-MS, in order to determine their viability as reference materials for Ti in quartz. Titanium contents in low-CL rims in the Bishop Tuff quartz grains were determined to be homogenous by EPMA (41 ± 2 µg/g Ti, 2σ), and are a potential natural reference material. We present a new method for determining 48Ti concentrations in quartz by LA-ICP-MS at the 1 µg/g level, relevant to quartz in HP-LT terranes. We suggest that natural quartz such as the homogeneous low-CL rims of the Bishop Tuff quartz are more suitable than NIST reference glasses as an in-house reference material for low Ti concentrations because matrix effects are limited and Ca isobaric interferences are avoided, thus allowing for the use of 48Ti as a normalizing mass. Titanium concentration from 33 analyses of low

  5. Orientation of tectonic stresses in central Kentucky during U. Devonian/L. Mississippian times: Evidence from quartz veins (after gypsum) in NE-trending, systematic joints in shales

    SciTech Connect

    Grover, J.; Dupuis-Nouille, E.M. . Dept. of Geology)

    1992-01-01

    Quartz replacing fibrous gypsum and anhydrite pseudomorphically (QAS; quartz after sulfate''), and preserving characteristic crack-seal'' and chickenwire'' textures, occurs in extensional veins at four locations in central KY. The veins occupy a systematic set of NE-SW-trending, vertical joints within the essentially flat-lying shales of the Renfro Member of the Mississippian Borden Formation and the Late Devonian New Albany Shale. The four QAS occurrences discovered to date are located northeast of the Borden Front. At one site in the New Albany Shale, QAS veins show clear evidence of penecontemporaneous deformation. It is proposed that at all QAS locations, gypsum precipitated in incipient joints before complete lithification of the sediment, and grew perpendicular to the fractures to form extensional veins in the soft but firm muds. The orientations of the joints now marked by QAS veins are broadly consistent with regional patterns of NE-SW-trending systematic joints and lineaments in southern IN and in central and eastern KY. These systematic fracture patterns do not correspond directly to known basement faults or rift systems, although they are consistent with modern stress directions in eastern and western KY, measured in situ in wells and by earthquake fault-plane solutions. It is proposed that this systematic trend marks the regional tectonic stress pattern characteristic of southern IN and central and eastern KY at, and since the Late Devonian. The evidence of penecontemporaneous sedimentary deformation in joints of U. Devonian age, marked and preserved by quartz replacement of early gypsum, is sufficient to show that while the systematic NE-trending joint set in KY may also be modern it is not uniquely so.

  6. Tracing the evolution of crustal-scale, transient permeability in a tectonically active, mid-crustal, low-permeability environment by means of quartz veins

    NASA Astrophysics Data System (ADS)

    Sintubin, M.

    2013-12-01

    In mid-crustal, low-permeability environments pervasive fluid flow is primarily driven by the production of internally-derived metamorphic fluids, causing a near permanent state of near-lithostatic fluid-pressure conditions. In a tectonically active crust, these overpressured fluids will generate intermittently an enhanced permeability that will facilitate fluid flow through the crust. The High-Ardenne slate belt (Belgium, France, Germany) can be considered as a fossil (late Palaeozoic) analogue of such mid-crustal, low-permeability environment at the brittle-plastic transition (depth range from 7 to 15 km). Low-grade metamorphic (250°C-350°C), predominantly fine-grained, siliciclastic metasediments were affected by a contraction-dominated deformation, materialized by a pervasive slaty cleavage. Quartz veins, abundantly present in the slate belt, are used as a proxy for the enhanced permeability. Detailed structural, petrographical, mineralogical and geochemical studies of different quartz-vein occurrences has enabled to reconstruct the evolution of the crustal-scale permeability , as well as to constrain the coupled fluid-pressure and stress-state evolution throughout the orogenic history. Extensive veining on a regional scale seems confined to periods of tectonic stress inversion, both at the onset (compressional stress inversion) and in the final stages (extensional stress inversion) of orogeny. Firstly, compressional stress inversion is expressed by pre-orogenic bedding-normal extension veins, consistently arranged in parallel arrays, followed by early orogenic bedding-parallel hybrid veins. Fluid-inclusion studies demonstrate near-lithostatic to supralithostatic fluid pressures, respectively. Secondly, discordant veins, transecting the pre-existing cleavage fabric, are interpreted to be initiated shortly after the extensional stress inversion, reflecting the late-orogenic extensional destabilisation of the slate belt. Veining again occurred at high fluid

  7. Multistage deformation of Au-quartz veins (Laurieras, French Massif Central): evidence for late gold introduction from microstructural, isotopic and fluid inclusion studies

    NASA Astrophysics Data System (ADS)

    Essarraj, S.; Boiron, M.-C.; Cathelineau, M.; Fourcade, S.

    2001-07-01

    The relative chronology of fluid migration, quartz and Au-deposition in a silicified fault from the main Au-district (Laurieras, St Yrieix district) from northern French Massif Central has been determined from microstructural, fluid inclusion, isotopic and ore mineral evidences. Three main stages of fluid circulation, microfracturing and quartz crystallization, and ore deposition were distinguished on the basis of textural relationships and the pressure, temperature and composition of the palaeo-fluids: (1) a series of early fluid events was responsible for the localized drainage of retrograde metamorphic fluids along the main fault and the subsequent sealing by milky and microcrystalline quartz preceeded the main Au-ore stages. Early fluids were aqueous-carbonic, trapped under lithostatic to sublithostatic pressures at temperatures in the range 350-500°C. Subsequently, several types of microstructures were developed in the early quartz matrix. (2) NS microfractures filled by clear quartz, arsenopyrite and boulangerite (I) contain significant refractory gold concentrations. Clear quartz formed from aqueous-carbonic fluids of lower densities than those of the earlier fluids. Significant pressure drops, down to pressures around 55 MPa were responsible for a local immiscibility of the aqueous-carbonic fluids at temperatures of 340±20°C. (3) The main ore stage is characterized by the formation of dense sets of sub-vertical (EW) microfractures, healed fluid inclusion planes in quartz, and filled by ore minerals (native gold, galena and boulangerite II) when they crosscut earlier sulfides. The fluids are aqueous with low and decreasing salinity, and probable trapping temperatures around 230°C. Isotopic data, obtained on microfissured quartz, indicate these dilute aqueous fluids may be considered as meteoric waters that deeply infiltrated the crust. Late microfissuring of a mesothermal quartz vein, originally barren (only with pyrite and arsenopyrite), appears to be

  8. Oxygen isotope record of fluid-rock-SiO 2 interaction during Variscan progressive deformation and quartz veining in the meta-volcanosediments of Belle-Ile (Southern Brittany)

    NASA Astrophysics Data System (ADS)

    Schulz, Bernhard; Audren, Claude; Triboulet, Claude

    2002-08-01

    Belle-Ile in the South Armorican Domain is composed of Palaeozoic volcano-detrital sequences with sericite phyllites and porphyroids. Fine-banded and folded meta-tuffites, microquartzites and graphitic quartzites occur in the basal part at Plage de Bordardoué. Phengite compositions constrain that Variscan metamorphism did not exceed 430 °C/4.5 kbar. Four generations (1-4) of centimeter-thick quartz veins were precipitated during Variscan progressive deformation and recorded changing fluid compositions. Values of 26‰ δ18O SMOW in vein 1 quartz exceed high δ18O SMOW in the host rocks. Decrease of quartz δ18O SMOW from margins to centers can be observed from the syntaxial veins. Younger veins 4 have lower δ18O. Their inclusions indicate lower salinities and traces of CH 4 in the fluid when compared with veins 1. Veins 1 were overprinted by shearing and fissuring. Subgrain rotation recrystallization occurred along briquette structures and subgrain boundaries. The initial isotope values have been preserved. Larger domains with small-grained quartz can be identified by lower values of δ18O. Homogeneous isotopic compositions are found in hinges of folded veins 2 with grain boundary migration recrystallization. The small-scale oxygen isotope variations and the changing fluid compositions point to a locally hosted fluid system with a limited contribution of meteoric water during multiphase deformation and vein formation.

  9. Quartz veins deformed by diffusion creep-accommodated grain boundary sliding during a transient, high strain-rate event in the Southern Alps, New Zealand

    NASA Astrophysics Data System (ADS)

    Wightman, Ruth H.; Prior, David J.; Little, Timothy A.

    2006-05-01

    The crystallographic preferred orientations (CPOs) and microstructures of deformed quartz veins were measured for four samples in the hanging-wall of the Alpine Fault in the Southern Alps, New Zealand. Their deformation and exhumation has occurred since 4 Ma. The quartz veins have been ductilely sheared to finite shear-strains of 5-15 in late Cenozoic shear zones at 450±50 °C, 310±90 MPa and strain-rates between 2×10 -11 and 2×10 -9 s -1. The sheared veins have a polygonal microstructure with few subgrains and an average grain-size of ˜100 μm. The CPO of the veins is random to very weak within the shear zones. We suggest that dislocation creep accommodated initial shear deformation, at high stresses and strain-rates. The deformation must have created a strong CPO and concomitant dynamic recrystallization reduced the grain-size significantly. Dissipation of stresses during initial deformation lead to a stress and strain-rate drop required for a switch to diffusion creep-accommodated grain boundary sliding (GBS). Continued shearing accommodated by GBS destroyed the CPO. Post-deformational grain growth gave rise to a final polygonal microstructure with a similar grain size in veins and in the wall rocks. Analysis of existing experimental data suggest that this sequence of events is possible in the time available. Rates of all processes may have been enhanced by the presence of a water-rich fluid within the shear zones. These observations of naturally deformed rocks provide a model for the processes that may occur during short-lived deformation at transiently-high stresses at mid-crustal depths or deeper.

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

    NASA Astrophysics Data System (ADS)

    Kidder, S.; Avouac, J.-P.; Chan, Y.-C.

    2013-01-01

    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 temperatures as low as ~250 °C, however

  11. Huebnerite veins near Round Mountain, Nye County, Nevada

    SciTech Connect

    Shawe, D.R.; Foord, E.E.; Conklin, N.M.

    1984-01-01

    Small huebnerite-bearing quartz veins occur in and near Cretaceous (about 95 m.y. old) granite east and south of Round Mountain. The veins are short, lenticular, and strike mostly northeast and northwest in several narrow east-trending belts. The quartz veins were formed about 80 m.y. ago near the end of an episode of doming and metamorphism of the granite and emplacement of aplite and pegmatite dikes in and near the granite. An initial hydrothermal stage involved deposition of muscovite, quartz, huebnerite, fluorite, and barite in the veins. Veins were then sheared, broken, and recrystallized. A second hydrothermal stage, possibly associated with emplacement of a rhyolite dike swarm and granodiorite stock about 35 m.y. ago, saw deposition of more muscovite, quartz, fluorite, and barite, and addition of scheelite, tetrahedrite-tennantite, several sulfide minerals, and chalcedony. Finally, as a result of near-surface weathering, secondary sulfide and numerous oxide, tungstate, carbonate, sulfate, phosphate, and silicate minerals formed in the veins. Depth of burial at the time of formation of the veins, based on geologic reconstruction, was about 3-3.5 km. The initial hydrothermal stage ended with deposition of quartz at a temperature of about 210/sup 0/C and pressures of about 240 to 280 bars from fluids with salinity of about 5 wt % sodium chloride. Fluorite then was deposited at about 250/sup 0/ to 280/sup 0/C from solutions of similar salinity and containing a small amount of carbon dioxide. During shearing that followed initial mineralization, quartz was recrystallized at a temperature of 270/sup 0/ to 290/sup 0/C and in association with fluids of about 5 wt % sodium chloride equivalent and containing carbon dioxide. Late-stage fluorite was deposited from fluids with similar salinity but devoid of carbon dioxide at a temperature of about 210/sup 0/C. 76 refs., 38 figs., 8 tabs.

  12. An X-ray excited optical luminescence study of a zoned quartz crystal from an emerald-bearing quartz vein, Hiddenite, North Carolina, USA

    NASA Astrophysics Data System (ADS)

    Jürgensen, Astrid; Anderson, Alan J.; Sham, Tsun-Kong

    2009-04-01

    The optical luminescence excited with synchrotron radiation along a preferential orientation of a quartz crystal has been investigated. It is found that the crystal is composed of two distinct regions, only one of which luminesces upon X-ray excitation. This luminescence is generally uniform and exhibits emission bands in the blue (470 nm with a shoulder at 522 nm) and in the UV (340 nm) regions of the spectrum. The branching ratio for the intensity of these bands is sensitive to the excitation energy across the Si K-edge. XANES spectra collected by partial luminescence yield (PLY) suggest that both emission bands originate from the de-excitation of Si atoms in the quartz. The possible defect sites within the crystal structure that could account for the observed luminescence are investigated and discussed. Additional experiments are proposed to verify this assignment of the optical emission bands.

  13. Formation of parting in quartz

    NASA Astrophysics Data System (ADS)

    Jørgen Kjøll, Hans; Eske Sørensen, Bjørn

    2014-05-01

    This paper presents hydrothermal quartz with macroscopic planar parting from the Mesoproterozoic Modum complex in southern Norway. Similar macroscopic parting in hydrothermal quartz with macroscopic planar structures has only been described from two localities in the world; Madagascar (Flörke et al., 1981) and Southern California (Murdoch et al., 1938). The study area consists of well foliated and banded sillimanite- garnet- amphibolite- mica gneiss that is cut at high angle by hydrothermal veins containing albite, chlinoclore, hornblende, hydroxyl apatite and quartz. The rim of the veins is generally made up of almost pure end-member euhedral albite. Then there is vugs with euhedral hornblende (10-25cm long) and euhedral hydroxyl apatite with size ranging from mm scale to several cm. Some places the quartz encloses apatite and hornblende. The quartz is anhedral, inequigranular with undulose extinction bordering sub grain rotation. It has large planar penetrative parting faces with pearly luster; however this is not consistent throughout the outcrop and some places the penetrative faces disappears and the quartz has a conchoidal fracture. The planar faces continue throughout the specimens with a few mm spacing. Thin sections oriented perpendicular to the most pronounced planar structure show lamellas that extinguishes at small angles (2 degrees) to each other. EBSD mapping of the planar faces shows two orientations {0-111} and {1-101}, corresponding to the r- and z-faces respectively, separated by irregular boundaries. The misorientation between these two crystallographic orientations on the parting is a 60 degree rotation on [0 0 1] in correspondence to the dauphiné twin law. Investigations conducted on thin sections cut orthogonal to the parting shows that the parting cuts and offsets the dauphiné twins, indicating a late genesis of the parting. However some internal stress induced movement of the twins are visible. SEM-CL documents three generations of quartz

  14. Partitioning and Leaching Behavior of Actinides and Rare Earth Elements in a Zirconolite- Bearing Hydrothermal Vein System

    SciTech Connect

    Payne, Timothy E.; Hart, Kaye P.; Lumpkin, Gregory R.; McGlinn, Peter J.; Giere, Reto

    2007-07-01

    Chemical extraction techniques and scanning electron microscopy were used to study the distribution and behavior of actinides and rare earth elements (REE) in hydrothermal veins at Adamello (Italy). The six samples discussed in this paper were from the phlogopite zone, which is one of the major vein zones. The samples were similar in their bulk chemical composition, mineralogy, and leaching behavior of major elements (determined by extraction with 9 M HCl). However, there were major differences in the extractability of REE and actinides. The most significant influence on the leaching characteristics appears to be the amounts of U, Th and REE incorporated in resistant host phases (zirconolite and titanite) rather than readily leached phases (such as apatite). Uranium and Th are very highly enriched in zirconolite grains. Actinides were more readily leached from samples with a higher content of U and Th, relative to the amount of zirconium. The results show that REE and actinides present in chemically resistant host minerals can be retained under aggressive leaching conditions. (authors)

  15. Effects of quartz particle size and water-to-solid ratio on hydrothermal synthesis of tobermorite studied by in-situ time-resolved X-ray diffraction

    SciTech Connect

    Kikuma, J.; Tsunashima, M.; Ishikawa, T.; Matsuno, S.; Ogawa, A.; Matsui, K.; Sato, M.

    2011-08-15

    Hydrothermal synthesis process of tobermorite (5CaO.6SiO{sub 2}.5H{sub 2}O) has been investigated by in-situ X-ray diffraction using high-energy X-rays from a synchrotron radiation source in combination with a purpose-build autoclave cell. Dissolution rates of quartz were largely affected by its particle size distribution in the starting mixtures. However, the composition (Ca/Si) of non-crystalline C-S-H at the start of tobermorite formation was identical regardless of the quartz dissolution rate. An effect of water-to-solid ratio (w/s) was investigated for samples using fine particle quartz. Tobermorite did not occur with w/s of 1.7 but occurred with w/s higher than 3.0. Surprisingly, however, the dissolution curves of quartz were nearly identical for all samples with w/s from 1.7 to 9, indicating that the dissolution rate is predominated by surface area. Possible reaction mechanism for tobermorite formation will be discussed in terms of Ca and/or silicate ion concentration in the liquid phase and distribution of Ca/Si in non-crystalline C-S-H. - Graphical abstract: Time-resolved XRD data set was obtained at up to 190 deg. C under a saturated steam pressure. Tobermorite (5CaO.6SiO{sub 2}.5H{sub 2}O) formation reaction was investigated in detail for several different starting materials. Highlights: > Hydrothermal formation of tobermorite was monitored by in-situ XRD. > Ca/Si of C-S-H at the start time of tobermorite formation was determined. > The Ca/Si value was identical regardless of the quartz particle size in the starting mixture.

  16. Precipitation of uraninite in chlorite-bearing veins of the hydrothermal alteration zone (argile de pile) of the natural nuclear reactor at Bangombe, Republic of Gabon

    SciTech Connect

    Eberly, P.; Ewing, R.; Janeczek, J.

    1995-12-31

    This paper describes the mineralogy of a phyllosilicate/uraninite/galena-bearing vein located within the hydrothermal alteration halo associated with the Bangombe reactor. Phyllosilicates within the vein include a trioctahedral Al-Mg-Fe chlorite (ripidolite), Al-rich clay (kaolinite and/or donbassite) and illite. Textural relations obtained by backscattered-electron imaging suggest that ripidolite crystallized first among the sheet silicates. Uraninite is spatially associated with ripidolite and probably precipitated at a later time. While energy-dispersive X-ray analyses suggest that the uranium phase is predominantly uraninite, coffinite or other phases may also be present.

  17. Zonation of primary haloes of Atud auriferous quartz vein deposit, Central Eastern Desert of Egypt: A potential exploration model targeting for hidden mesothermal gold deposits

    NASA Astrophysics Data System (ADS)

    Harraz, Hassan Z.; Hamdy, Mohamed M.

    2015-01-01

    The Atud gold mine located in the Neoproterozoic diorite and metagabbro of the Central Eastern Desert of Egypt has been initially excavated during Pharaonic times. Between 1953 and 1969, the Egyptian Geological Survey and Mining Authority performed underground prospection in the auriferous quartz vein and metasomatic alteration zones in the main Atud area, estimating a principal gold lode of 19,000 tones (16.28 g/ton), and 1600 tons of damp (1.24 g/ton). Yet the potentiality of the deposit has not been exhausted. However, for exploration of hidden ore, quantitative characterization using trace elements zoning of mineralization haloes with 280 samples from surface and three underground mining levels is applied. This was through multivariate statistical analysis (Factor analysis) of 11 selected trace elements. Axial (vertical) extents of primary haloes above and beneath gently dipping orebody are also visualized to interpret the level of erosion, determine the direction of mineralizing solutions as well as to examine whether the hidden orebody is promising at the Atud mine. Axial zones of primary dispersion aureoles of trace elements are: Ag, As, S and U around the auriferous quartz veins; Cu, and Pb in the surface horizons; and Zn, Ni, Co, and U along the lower margin of mineralization zone. Gold contents in bedrock and quartz vein samples from level-42M are the highest (5.7 and 40.3 ppm, respectively). In the transverse (lateral) direction, the maximum relative accumulation of Au and Zn occurs at the Northern Shaft; Pb, Cu, As, and U at the Main Shaft; and Ag, S, Co, and Ni at the Southern Shaft. The estimated axial zonation sequence of indicator elements using the variability index is Pb → Cu → Ag → Au → As → S → Ni → Co → U → Zn. According to this zonation, an index such as (Pb × Cu)D/(U × Zn)D can be a significant for predicting the Au potentiality at a particular depth. In addition, the Pb/U zonality index is an appropriate indicator for the

  18. Quartz diorite veins in a peridotite xenolith from Tallante, Spain: implications for reaction and survival of slab-derived SiO2-oversaturated melt in the upper mantle

    NASA Astrophysics Data System (ADS)

    Arai, S.; Shimizu, Y.; Gervilla, F.

    We found quartz diorite veins (up to 5 mm thick), composed mainly of plagioclase and quartz, in a plagioclase-bearing spinel lherzolite xenolith in alkali basalt from Tallante, Southern Spain. The quartz diorite veins are coarse-grained, the average grain size being 0.5 mm, and have thin orthopyroxenite rim along olivine wall. Thinner veins free of quartz and composed solely of plagioclase with orthopyroxene selvage are much more common in other xenoliths from Tallante. The involved melt was strongly reactive with olivine to form orthopyroxene, which can protect against further reaction. This suggests how the silica-oversaturated melts, after supplied from downgoing slabs, can move through peridotite and reach the shallow mantle with preserving the silica-oversaturated character. The armor of orthopyroxenite is of vital importance for the melt to keep its silica-oversaturated character within peridotite. Precipitation of orthopyroxene combined with olivine consumption somewhat controls the general chemical trend of adakite. Orthopyroxenite vein network at the expense of olivine is expected to be common as fossil conduits within the mantle wedge. This kind of orthopyroxenite has contributed to Si-enrichment of the mantle wedge.

  19. The Laramide Caborca orogenic gold belt of northwestern Sonora, Mexico; white mica 40Ar/39Ar geochronology from gold-rich quartz veins

    USGS Publications Warehouse

    Izaguirre, Aldo; Kunk, Michael J.; Iriondo, Alexander; McAleer, Ryan; Caballero-Martinez, Juan Antonio; Espinosa-Arámburu, Enrique

    2016-01-01

    The COGB is approximately 600 kilometers long and 60 to 80 km wide, trends northwest, and extends from west-central Sonora to southern Arizona and California. The COGB contains mineralized gold-rich quartz veins that contain free gold associated with white mica (sericite), carbonate minerals (calcite and ankerite), and sulfides such as pyrite and galena. Limited geochronologic studies exist for parts of the COGB, and previous work was concentrated in mining districts. These previous studies recorded mineralization ages of approximately 70 to 40 Ma. Therefore, some workers proposed that the orogenic gold mineralization in the region occurred during a single pulse that was associated with the Laramide Orogeny that took place during the Cretaceous to early Eocene in the western margin of North America. However, the geochronologic dataset was quite limited, making any regional interpretations tenuous. Accordingly, one of the objectives of this geochronology study was to get a better representative sampling of the COGB in order to obtain a more complete record of the mineralization history. The 63 samples presented in this work are broadly distributed throughout the area of the COGB and allow us to better test the hypothesis that mineralization occurred in a single pulse.

  20. Distribution of fluid inclusions in igneous quartz of the Capitan pluton, New Mexico, USA

    NASA Astrophysics Data System (ADS)

    Ratajeski, Kent; Campbell, Andrew R.

    1994-02-01

    Fluid inclusions in granites have been used extensively in studies of magmatic-hydrothermal processes, but few studies have documented the distribution of secondary fluid inclusions within the nonmineralized main body of an intrusion. Previous work on fluid inclusions in Th-U-REE quartz/ fluorite vein deposits in the Capitan pluton suggests that these veins resulted from high-temperature, high-salinity, magmatic fluids in fractured and brecciated zones in the cooled outer carapace of the pluton. Petrographic examination of phenocryst quartz in forty-four thin sections of granite from the Capitan pluton reveals that these same fluids are found in secondary fluid inclusions. Fluid inclusions with daughter minerals commonly occur in the outer granophyre and aplite zones, but are usually absent in the porphyritic core. Microthermometric data and calculated salinities from fifty-eight fluid inclusions in phenocryst quartz and thirty-one fluid inclusions in miarolitic quartz (both samples taken from the granophyre zone) also correlate fairly well with the data from the Th-U-REE quartz/fluorite vein deposits, and similar types of fluid inclusions are found in all three occurrences of quartz. A major difference, however, is that vapor-rich inclusions, abundant as secondary inclusions in igneous phenocryst quartz, are extremely scarce in the vein quartz. Liquid-vapor homogenization temperatures of high-salinity inclusions in phenocryst quartz range from 204-509°C with an average of 384°C. Halite dissolution temperatures of high salinity inclusions range from 442-583°C with an average of 525°C. Total homogenization temperatures are not as well documented due to decrepitation of many of the high salinity inclusions before total homogenization. Samples of miarolitic quartz appear to contain more low-salinity fluid inclusions than the phenocryst quartz, but high-salinity inclusions are present as well. These observations suggest that the magmatic-hydrothermal fluids

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Bell, Robin-Marie; Kolb, Jochen; Waight, Tod Earle; Bagas, Leon; Thomsen, Tonny B.

    2016-07-01

    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 its closure in 2014, having produced 10.67 t of gold. This study uses a combination of field investigation, petrography and U/Pb zircon and titanite geochronology to define a multi-stage hydrothermal alteration system at Nalunaq. A clinopyroxene-plagioclase-garnet(-sulphide) alteration zone (CPGZ) developed in the Nanortalik Peninsula, close to regional peak metamorphism and prior to gold-quartz vein formation. The ca. 1783-1762-Ma gold-quartz veins are hosted in reactivated shear zones with a hydrothermal alteration halo of biotite-arsenopyrite-sericite-actinolite-pyrrhotite(-chlorite-plagioclase-löllingite-tourmaline-titanite), which is best developed in areas of exceptionally high gold grades. Aplite dykes dated to ca. 1762 Ma cross-cut the gold-quartz veins, providing a minimum age for mineralisation. A hydrothermal calcite-titanite alteration assemblage is dated to ca. 1766 Ma; however, this alteration is highly isolated, and as a result, its field relationships are poorly constrained. The hydrothermal alteration and mineralisation is cut by several generations of ca. 1745-Ma biotite granodiorite accompanied by brittle deformation. A ca. 1745-Ma lower greenschist facies hydrothermal epidote-calcite-zoisite alteration assemblage with numerous accessory minerals forms halos surrounding the late-stage fractures. The contrasting hydrothermal alteration styles at Nalunaq indicate a complex history of exhumation from amphibolite facies conditions to lower greenschist facies conditions in an orogenic belt which resembles modern Phanerozoic orogens.

  3. Involvement of Overpressured Fluids in the Nucleation of High-Angle Reverse Ruptures: Evidence from Fault-Hosted Hydrothermal Vein Systems

    NASA Astrophysics Data System (ADS)

    Sibson, R. H.

    2007-12-01

    Dips of near-pure reverse-slip M>5.5 ruptures are bimodally distributed with a dominant peak at δ = 30±5°, a subordinate peak at δ = 50±5°, and no ruptures with δ > 60°. Assuming horizontal trajectories for maximum compressive stress (σ1), the dominant peak corresponds to optimally oriented faults with Byerlee friction coefficients (μs = 0.6) for which frictional lock-up is expected at δ = 60°. In recent years, several compressional inversion earthquakes in the upper crust of Honshu, Japan (e.g. the 2003 Mw6.5 Northern Miyagi, the 2004 Mw6.6 Mid-Niigata Prefecture, and the 2007 Mw6.7 Noto-Hanto sequences) have involved high-angle reverse-slip with dips of 50-60° on inherited normal faults along the margins of Miocene extensional basins. Rupturing during these earthquakes thus took place on faults that were poorly oriented for frictional reactivation and close to lock-up. Frictional mechanics suggests that reshear of the steep reverse faults (in preference to the formation of new favorably oriented thrusts within intact crust) is allowable only under near- lithostatic fluid pressures with Pf approaching σ3, and that reshear of severely misoriented faults (δ > c.60°) requires Pf > σ3 (the hydrofracture condition). Notably, the 2004 Mid-Niigata sequence involved a criss-crossing network of high-angle and low-angle reverse ruptures, suggesting competition between reshear of steep inherited faults and the formation of more favorably oriented thrusts. A range of geophysical evidence, including local bright S-wave reflectors, indicates strong fluid overpressuring in the focal regions of these earthquakes. Mesozonal Au-quartz vein systems hosted in reverse faults exhumed from depths corresponding to the lower half of the seismogenic zone (P ~ 2-4 kbar; T ~ 250-400°C) occur throughout the geological record and provide additional evidence for the involvement of strongly overpressured fluids in reverse fault rupturing. Incrementally deposited fault

  4. Time scales of porphyry Cu deposit formation: insights from titanium diffusion in quartz

    USGS Publications Warehouse

    Mercer, Celestine N.; Reed, Mark H.; Mercer, Cameron M.

    2015-01-01

    Porphyry dikes and hydrothermal veins from the porphyry Cu-Mo deposit at Butte, Montana, contain multiple generations of quartz that are distinct in scanning electron microscope-cathodoluminescence (SEM-CL) images and in Ti concentrations. A comparison of microprobe trace element profiles and maps to SEM-CL images shows that the concentration of Ti in quartz correlates positively with CL brightness but Al, K, and Fe do not. After calibrating CL brightness in relation to Ti concentration, we use the brightness gradient between different quartz generations as a proxy for Ti gradients that we model to determine time scales of quartz formation and cooling. Model results indicate that time scales of porphyry magma residence are ~1,000s of years and time scales from porphyry quartz phenocryst rim formation to porphyry dike injection and cooling are ~10s of years. Time scales for the formation and cooling of various generations of hydrothermal vein quartz range from 10s to 10,000s of years. These time scales are considerably shorter than the ~0.6 m.y. overall time frame for each porphyry-style mineralization pulse determined from isotopic studies at Butte, Montana. Simple heat conduction models provide a temporal reference point to compare chemical diffusion time scales, and we find that they support short dike and vein formation time scales. We interpret these relatively short time scales to indicate that the Butte porphyry deposit formed by short-lived episodes of hydrofracturing, dike injection, and vein formation, each with discrete thermal pulses, which repeated over the ~3 m.y. generation of the deposit.

  5. Tourmaline nodules: indicators of hydrothermal alteration and SnZn(W) mineralization in the Cape Granite Suite, South Africa

    NASA Astrophysics Data System (ADS)

    Rozendaal, A.; Bruwer, L.

    1995-07-01

    Tourmaline and quartz-tourmaline nodular aggregates are common in S-type granitoids of the Cape Granite Suite in the Tygerberg terrane of the Neoproterozoic Saldania belt, South Africa. Most of the aggregates occur within the 200 km long Yzerfontein-Helderberg linear zone, which hosts a diversity of exo- and endomagmatic base and precious metal deposits. The conspicuous dark spherical nodules, with diameters of up to 40 cm, are surrounded by a leucocratic halo and consist mainly of tourmaline (schorl) and quartz. Spatial and temporal relationships indicate that the nodules are features of post-magmatic replacement related to the hydrothermal alteration of crystallized granite. Their distribution is possibly controlled by fluid movement along micro-fractures and diffusion along grain boundaries. Nodule composition suggests that the hydrothermal fluids that formed them were oxidizing and chemically simple, mainly B-(F)-rich and consequently acidic with anomalously high concentrations of Zn, Sn and Ga. Where proximal to Sn-Zn-(W) quartz-vein deposits, spatial relations show that nodule formation is more widespread than and preceded the vein mineralization. This relationship, coupled with the similar metal association of the nodules and veins, suggests a common hydrothermal fluid source. It also allows the use of tourmaline nodules as regional indicators of hydrothermal alteration and of late-stage vein deposits of similar metal association.

  6. Competitive hydration and dehydration at olivine-quartz boundary revealed by hydrothermal experiments: Implications for silica metasomatism at the crust-mantle boundary

    NASA Astrophysics Data System (ADS)

    Oyanagi, Ryosuke; Okamoto, Atsushi; Hirano, Nobuo; Tsuchiya, Noriyoshi

    2015-09-01

    Serpentinization occurs via interactions between mantle peridotite and water that commonly passes through the crust. Given that such a fluid has a high silica activity compared with mantle peridotite, it is thought that serpentinization and silica metasomatism occur simultaneously at the crust-mantle boundary. In this study, we conducted hydrothermal experiments in the olivine (Ol)-quartz (Qtz)-H2O system at 250 °C and vapor-saturated pressure under highly alkaline conditions (NaOHaq, pH = 13.8 at 25 °C) to clarify the mechanism of silica metasomatism at the crust-mantle boundary. Composite powders consisting of a Qtz layer and an Ol layer were set in tube-in-tube vessels. After the experiments, the extents of serpentinization and metasomatic reactions were evaluated as a function of distance from the Ol-Qtz boundary. The mineralogy of the reaction products in the Ol-hosted region changed with increasing distance from the Ol-Qtz boundary, from smectite + serpentine (Smc zone) to serpentine + brucite + magnetite (Brc zone). Olivine hydration proceeded in both zones, but the total H2O content in the products was greater in the Brc zone than in the Smc zone. Mass balance calculations revealed that olivine hydration occurred without any supply of silica in the brucite zone. In contrast, the Smc zone was formed by silica metasomatism via competitive hydration and dehydration reactions. In the Smc zone, smectite formed via the simultaneous progress of olivine hydration and serpentine dehydration, and around the boundary of the Smc and Brc zones, serpentine formation occurred by olivine hydration and brucite dehydration. The relative extent of hydration and dehydration reactions controlled the along-tube variation in the rate of H2O production/consumption and the rate of volume increase. Our findings suggest that the competitive progress of serpentinization and silica metasomatic reactions would cause fluctuations in pore fluid pressure, possibly affecting the

  7. Porphyry-Cu-Mo Stockwork Formation by Dynamic, Transient Hydrothermal Pulses: Mineralogic Insights From the Deposit at Butte, Montana

    NASA Astrophysics Data System (ADS)

    Mercer, C. N.; Reed, M. H.

    2011-12-01

    The temperature profile in magmatic-hydrothermal systems directly affects the chemical behavior and pressure regime of hydrothermal fluids and the resulting diversity of mineralization. We combine textural observations of igneous and hydrothermal minerals using SEM-CL and -BSE images with three independent mineral thermobarometers to better understand the thermal profile at the porphyry-Cu-Mo deposit in Butte, Montana. We apply the two most recent (and controversial) forms of the Ti-in-quartz thermobarometer from Thomas et al. (2010) and Huang and Audétat (2011), the Zr-in-rutile thermobarometer of Tomkins et al. (2007), and the XMg-Ti-in-biotite thermometer of Henry et al. (2005) to estimate the formation temperatures of these magmatic and hydrothermal minerals. In a comparison of isobaric temperature distributions from Ti-in-quartz (Thomas et al., 2010) and Zr-in-rutile we find that the Thomas et al. calibration consistently yields temperatures that are 50 to 200°C lower than those from Zr-in-rutile. These quartz temperatures are unreasonably low for quartz phenocrysts and are considerably lower than previous estimates for vein quartz. Temperature estimates from the Zr-in-rutile and XMg-Ti-in-biotite thermobarometers agree well with each other and with previous temperature estimates. We conclude that application of the Ti-in-quartz thermobarometer of Thomas et al. is not appropriate for this natural system. Quartz temperatures calculated using the calibration of Huang and Audétat (2011) are closer to those from rutile and biotite. Application of the Ti-in-quartz thermobarometer of Huang and Audétat to hydrothermal samples yields maximum temperature estimates, however, and requires evaluation of trace element abundances (e.g., Ti, Al) and other crystal lattice impurities (e.g., fluid inclusions) in growth zones as a means to determine whether growth zones represent slow or fast-growing quartz. Using thermobarometry from rutile, biotite, and quartz (Huang and

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

    NASA Astrophysics Data System (ADS)

    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

  9. Melt inclusions in veins: linking magmas and porphyry Cu deposits.

    PubMed

    Harris, Anthony C; Kamenetsky, Vadim S; White, Noel C; van Achterbergh, Esmé; Ryan, Chris G

    2003-12-19

    At a porphyry copper-gold deposit in Bajo de la Alumbrera, Argentina, silicate-melt inclusions coexist with hypersaline liquid- and vapor-rich inclusions in the earliest magmatic-hydrothermal quartz veins. Copper concentrations of the hypersaline liquid and vapor inclusions reached maxima of 10.0 weight % (wt %) and 4.5 wt %, respectively. These unusually copper-rich inclusions are considered to be the most primitive ore fluid found thus far. Their preservation with coexisting melt allows for the direct quantification of important oreforming processes, including determination of bulk partition coefficients of metals from magma into ore-forming magmatic volatile phases. PMID:14684818

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

    PubMed

    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). PMID:26790877

  11. Organic inclusions within hydrothermal minerals from S.W. Africa and elsewhere.

    NASA Technical Reports Server (NTRS)

    Mueller, G.

    1972-01-01

    It was observed that quartz crystals from veins within a diabase dike of precambrian age from S.W. Africa contain organic particles which closely resemble, in detailed morphology, coacervates, proteinoid microspheres or fossil and recent microorganisms. The microphotospectrographs in visible and near-ultraviolet light of these minute particles revealed a strong absorption peak at the vicinity of 4000 A, which is indicative of lipids. Hydrothermal mineral from veins from a number of other localities proved to contain the biomorphic organic particles. The theoretical significance of these organic particles is discussed with reference to problems of origin of life.

  12. Unravelling the deep fluid composition in the Taupo Volcanic Zone: insight into the magmatic-hydrothermal transition

    NASA Astrophysics Data System (ADS)

    Chambefort, I. S.; Lewis, B.; Boseley, C.; Begue, F.; Rae, A.

    2012-12-01

    The Ngatamariki Geothermal Field represents the only location in the Taupo Volcanic Zone where geothermal well drilling has intercepted intrusive rocks with a high temperature alteration halo. Thus it presents the perfect opportunity to study the magmatic-hydrothermal transition in the TVZ by characterising the nature of the deep magmatic fluids inferred to be linked to the geothermal heat source. In addition to the calc-alkaline Ngatamariki diorite (encountered in a 1985 drillhole; Wood, 1986), recent (2012) geothermal drilling encountered a quartz-phyric tonalite. After emplacement, these intrusions cooled, degassed, and produced a high temperature alteration halo, associated with intense quartz-illite/muscovite-pyrite alteration and pervasive quartz replacement of the overlying tuff-breccia. This alteration zone contains abundant high temperature quartz veins, similar to quartz veining stockwork characteristic of Porphyry Cu (±Au-Mo) systems. The recently encountered quartz-phyric tonalite contains common phenocrysts of quartz and pseudomorphs of plagioclase and minor ferromagnesian minerals (predominantly amphiboles) in a medium-grained, magnetite-bearing felsic groundmass. Quartz phenocrysts are generally rounded and embayed quartz eyes (≤1 cm diam.), or skeletal crystals. SEM-CL imaging was used to map the crystallisation history of the phenocrystic quartz in the tonalite and the quartz veins cross-cutting the diorite and overlying pyroclastic rocks. The quartz eyes show a complex growth history with zones of dissolution and recrystallisation. Skeletal quartz crystals also have complex zoning and are outlined by myrmekitic textures and/or dendritic overgrowths with the groundmass (granophyric textures). These features form in granites due to undercooling during shallow magmatic emplacement and are often associated with the exsolution of a volatile phase. Cathodoluminescence indicates that the edges of the quartz veins are lined by euhedral crystals

  13. High-angle reverse faults, fluid-pressure cycling, and mesothermal gold-quartz deposits

    NASA Astrophysics Data System (ADS)

    Sibson, Richard H.; Robert, Francois; Poulsen, K. Howard

    1988-06-01

    Many mesothermal gold-quartz deposits are localized along high-angle reverse or reverse-oblique shear zones within greenstone belt terrains. Characteristically, these fault-hosted vein deposits exhibit a mixed "brittle-ductile" style of deformation (discrete shears and vein fractures as well as a schistose shear-zone fabric) developed under greenschist facies metamorphic conditions. Many of the vein systems are of considerable vertical extent (>2 km); they include steeply dipping fault veins (lenticular veins subparallel to the shear-zone schistosity) and, in some cases, associated flats (subhorizontal extensional veins). Textures of both vein sets record histories of incremental deposition. We infer that the vein sets developed near the roofs of active metamorphic/magmatic systems and represent the roots of brittle, high-angle reverse fault systems extending upward through the seismogenic regime. Friction theory and field relations suggest that the high-angle reverse faults acted as valves, promoting cyclic fluctuations in fluid pressure from supralithostatic to hydrostatic values. Because of their unfavorable orientation in the prevailing stress field, reactivation of the faults could only occur when fluid pressure exceeded the lithostatic load. Seismogenic fault failure then created fracture permeability within the rupture zone, allowing sudden draining of the geopressured reservoir at depth. Incremental opening of flats is attributed to the prefailure stage of supralithostatic fluid pressures; deposition within fault veins is attributed to the immediate postfailure discharge phase. Hydrothermal self-sealing leads to reaccumulation of fluid pressure and a repetition of the cycle. Mutual crosscutting relations between the two vein sets are a natural consequence of the cyclicity of the process. Abrupt fluid-pressure fluctuations from this fault-valve behavior of reverse faults seem likely to be integral to the mineralizing process at this

  14. Fluid chemistry and evolution of hydrothermal fluids in an Archaean transcrustal fault zone network: The case of the Cadillac Tectonic Zone, Abitibi greenstone belt, Canada

    USGS Publications Warehouse

    Neumayr, P.; Hagemann, S.G.; Banks, D.A.; Yardley, B.W.D.; Couture, J.-F.; Landis, G.P.; Rye, R.

    2007-01-01

    Detailed fluid geochemistry studies on hydrothermal quartz veins from the Rouyn-Noranda and Val-d'Or areas along the transcrustal Cadillac Tectonic Zone (CTZ) indicate that unmineralized (with respect to gold) sections of the CTZ contained a distinct CO2-dominated, H2S-poor hydrothermal fluid. In contrast, both gold mineralized sections of the CTZ (e.g., at Orenada #2) and associated higher order shear zones have a H2O-CO2 ?? CH4-NaCl hydrothermal fluid. Their CO2/H2S ratios indicate H2S-rich compositions. The Br/Cl compositions in fluid inclusions trapped in these veins indicate that hydrothermal fluids have been equilibrated with the crust. Oxygen isotope ratios from hydrothermal quartz veins in the CTZ are consistently 2??? more enriched than those of associated higher order shear zones, which are interpreted to be a function of greater fluid/rock ratios in the CTZ and lower fluid/rock ratios, and more efficient equilibration of the hydrothermal fluid with the wall rock, in higher order shear zones. An implication from this study is that the lower metal endowment of the transcrustal CTZ, when compared with the higher metal endowment in higher order shear zones (ratio of about 1 : 1000), may be the result of the lack of significant amounts of H2O-H2S rich fluids in most of the CTZ. In contrast, gold mineralization in the higher order shear zones appear to be controlled by the high H2S activity of the aqueous fluids, because gold was likely transported in a bisulfide complex and was deposited during sulfidation reactions in the wall rock and phase separation in the quartz veins. ?? 2007 NRC Canada.

  15. Varicose Veins

    MedlinePlus

    Varicose veins are swollen, twisted veins that you can see just under the skin. They usually occur in ... of the body. Hemorrhoids are a type of varicose vein. Your veins have one-way valves that help ...

  16. Permeability enhancement during gold mineralization: Evidences from Kestanelik epithermal vein system, NW Turkey

    NASA Astrophysics Data System (ADS)

    Gulyuz, Nilay; Shipton, Zoe; Kuscu, Ilkay; Lord, Richard A.; Gladwell, David R.; Kaymakci, Nuretdin

    2016-04-01

    The most favourable and principal mineral deposition mechanism in low sulphidation epithermal systems is boiling. Mineralization in these systems occurs dominantly as veins and stockworks; therefore, structures play major role in the localization of epithermal fluid flow. Epithermal fluids rise from depth along structural conduits at high temperatures under enough pressure to prevent boiling. When the pressure drops suddenly (for instance, through faulting or any fracturing), boiling occurs, and CO2 and H2S are released to the vapour phase. Change in fluid chemistry due to the boiling causes first the base metals, and then the ore and gangue minerals to deposit in a well-recognized temporal and vertical sequence until all open spaces are filled. Vein infill in epithermal deposits indicate that mineralization is multiphase and associated with repeated and episodic fluid flow rather than a steady-state process. How can permeability enhancement be achieved after deposition of minerals in fractures and faults chokes permeable pathways and restrict fluid flow? Although geochemical aspects of LS epithermal systems are well known, limited studies exist on the permeability enhancement mechanisms in LS epithermal veins. The main aim of the study is to understand the permeability enhancement mechanisms in epithermal gold deposits by focussing on the structures and quartz textures of a well-preserved low sulphidation epithermal quartz vein/breccia system in Lapseki, NW Turkey. We revealed the kinematics of the structure-vein network by mapping the geometries of epithermal quartz veins and associated structures and collecting detailed structural data from them. In addition, we determined the different phases of fluid flow and mineralization with the cross-cutting and structural relationships among them by examining the quartz textures and breccias and mapping their spatial distribution on vein outcrops and in drill cores with the help of thin section analyses. On-going work

  17. Deposition conditions and distribution features of native gold individuals in the veins of the Tokur mesothermal deposit, Russia

    NASA Astrophysics Data System (ADS)

    Ostapenko, N. S.; Neroda, O. N.

    2016-05-01

    The paper discusses factors in the deposition and concentration of native gold and the spatial distribution of its individuals within the sufide-poor gold-quartz veins at the mesoabyssal Tokur deposit. The major factors in deposition of gold were sealing of the hydrothermal system, a sudden drop in fluid pressure, and repeated immiscibility in the fluid. Native gold was deposited in relation to initial acts of prolonged and discrete opening and preopening of cavities in three mineral assemblages of the productive association II. Most native gold individuals with a visible size of 0.1-1.5 mm were together with the early generation of quartz 2 on cavity walls adjacent to altered rocks. This is caused by the high content of Au complexes in initial hydrothermal solutions favoring rapid oversaturation during cavity formation. Gold fills interstices between grains of quartz 2 throughout the deposit and mineral assemblages. The vertical-flow distribution of gold has been established in economic veins; the upper and middle levels are enriched in gold, and samples with the greatest gold grade of 100-500 g/t or higher are concentrated there. This is caused both by the predominance of mineral association II at these levels and probable natural flotation of gold grains contained in the gold-gas associate for immiscibility of the hydrothermal fluid at the second stage of the ore-forming process.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    and tip lines, we try to sort out if a dominant σ2 propagation direction, typical for hydrofractures, exists within the vein network. By doing so, we can evaluate whether the subhorizontal vein network formed under a compressive stress regime, or was mainly dictated by the strength anisotropy of the rocks under near-isotropic stress conditions of σhmax ≡ σhmin. The regional dominance of subhorizontal aplites, pegmatites and hydrothermal veins, exploiting subhorizontal fracture networks, occurs over a wide area of more than 100 km2 along the Serra de Estrela granitic massif (Derré et al., 1986). This orientation contrasts with the more common vertical attitude of granite-related hydrothermal veins, observed throughout the Iberian massif. A detailed orientation analysis of the fracture sets should allow to explore the possible causes of this particular late orogenic, flat-lying fracture network related to the granitic intrusion. References Derré, C., Lecolle, M., Roger, G., Tavares de Freitas Carvalho, J., 1986. Tectonics, magmatism, hydrothermalism and sets of flat joints locally filled by Sn-W, aplite-pegmatite and quartz veins, southeastern border of the Serra de Estrela granitic massif (Beira Baixa, Portugal). Ore Geology Reviews 1, 43-56. Foxford, K. A., Nicholson, R., Polya, D. A., and Hebblethwaite, R. P. B., 2000. Extensional failure and hydraulic valving at Minas da Panasqueira, Portugal; evidence from vein spatial distributions, displacements and geometries. Journal of Structural Geology 22, 1065-1086.

  19. Portovelo: a volcanic-hosted epithermal vein-system in Ecuador, South America

    NASA Astrophysics Data System (ADS)

    van Thournout, F.; Salemink, J.; Valenzuela, G.; Merlyn, M.; Boven, A.; Muchez, P.

    1996-05-01

    The Portovelo epithermal vein-system in southwestern Ecuador has produced more than 120 tons of gold and about 250 tons of silver. The veins result from hydrothermal processes close to a Miocene volcano which produced an andesitic to dacitic sequence followed by collapse and post-collapse rhyolitec activity which generated most of the alteration and mineralization. Three main structural segments are defined by NW-trending strike-slip faults, which show later stages of vertical movement. These faults are responsible for development of an extensive N-S dilatational jog within andesitic rocks, which acted as the main host to ore-deposition. A large-scale propylitic aureole surrounds a quartz-chloritesericite-adularia core, centered on the rhyolites, within a system of collapse-related ring-structures. A quartz-chlorite-sericite-adularia-calcite assemblage is the most common wall-rock alteration close to the veins. The size (4 × 15 km) and vertical range (1400 m) of the vein-system is exceptional. Alteration, textures and mineral assemblage, including a quartz-calcite gangue, sulfides, abundant sulfosalts and free gold (electrum), are quite typical of an adularia-sericite epithermal deposit. Spatially, the mineralization is arranged in three zones. In addition, three successive stages can be distinguished. The bulk of economic mineralization was deposited during the second stage, in association with a clear quartz and calcite gangue. Tm-ice and Tm-clath data of fluid inclusions in the clear quartz indicate a high salinity (˜ 10.5 eq. wt% NaCI). The homogenization temperatures of fluid inclusions in the gangue minerals and in the altered host-rocks vary between 180° and 310°C. Quartz δ 18O-values from hydrothermally altered wall-rocks reflect the original isotopic values of the latter. These values show a narrower range in vein quartz ( δO18 between +7.7‰ and +11.57‰ SMOW). In addition, the δO18 values of the vein quartz increase systematically with

  20. Varicose Veins

    MedlinePlus

    ... page from the NHLBI on Twitter. What Are Varicose Veins? Español Varicose (VAR-i-kos) veins are swollen, ... can form in other parts of the body. Varicose veins are a common condition. They usually cause few ...

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

    NASA Astrophysics Data System (ADS)

    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

  2. Impact-generated Hydrothermal Activity at the Chicxulub Crater

    NASA Astrophysics Data System (ADS)

    Kring, D. A.; Zurcher, L.; Abramov, O.

    2007-05-01

    Borehole samples recovered from PEMEX exploration boreholes and an ICDP scientific borehole indicate the Chicxulub impact event generated hydrothermal alteration throughout a large volume of the Maya Block beneath the crater floor and extending across the bulk of the ~180 km diameter crater. The first indications of hydrothermal alteration were observed in the crater discovery samples from the Yucatan-6 borehole and manifest itself in the form of anhydrite and quartz veins. Continuous core from the Yaxcopoil-1 borehole reveal a more complex and temporally extensive alteration sequence: following a brief period at high temperatures, impact- melt-bearing polymict breccias and a thin, underlying unit of impact melt were subjected to metasomatism, producing alkali feldspar, sphene, apatite, and magnetite. As the system continued to cool, smectite-series phyllosilicates appeared. A saline solution was involved. Stable isotopes suggest the fluid was dominated by a basinal brine created mostly from existing groundwater of the Yucatan Peninsula, although contributions from down-welling water also occurred in some parts of the system. Numerical modeling of the hydrothermal system suggests circulation occurred for 1.5 to 2.3 Myr, depending on the permeability of the system. Our understanding of the hydrothermal system, however, is still crude. Additional core recovery projects, particularly into the central melt sheet, are needed to better evaluate the extent and duration of hydrothermal alteration.

  3. The Benedikt hydrothermal system (north-eastern Slovenia)

    NASA Astrophysics Data System (ADS)

    Kralj, Peter; Eichinger, Lorenz; Kralj, Polona

    2009-10-01

    Deep welling in the Benedikt area has proven the existence of recently active hydrothermal system in pre-Tertiary basement composed of banded gneiss, marble and schist originating from a regionally metamorphosed sequence of clastic sediments. Two aquifers with very high fracture porosity were tapped—at depths between 1,485-1,530 and 1,848-1,857 m, where the welling stopped owing to a technical failure. The water temperature exceeds 90°C, while the yield of 100 l/s is limited only by the well performances. The Na-HCO3 dominated water is classified as a CO2-rich healing mineral water suitable for drinking, bottling and balneology. The free degassing gas is almost pure CO2 (99.9 %) and its δ13C composition indicates volcanic origin. The tapped water is relatively old, probably of Pleistocene age at least, and the planned exploitation must consider reinjection in order to protect this valuable natural resource from overexploitation. This recent hydrothermal system is characterised by dominating vertical circulation of waters and is superimposed on older, already inactive hydrothermal system(s), recognised by veins of either metal sulphides and quartz, or calcite. These vein minerals precipitated from hydrothermal fluids migrating from a deeper source towards the ancient surface through a fracture system, which is now self-sealed already. The distribution of metal sulphides indicates that the source might have been a deep-seated Neogene pluton genetically related to the tonalites and quartz diorites that outcrop in the Pohorje Mountains, or a subvolcanic-level volcanic body related to the Neogene volcanic activity in the Graz Basin.

  4. Hydrothermal uranium deposits containing molybdenum and fluorite in the Marysvale volcanic field, west-central Utah

    USGS Publications Warehouse

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

    1998-01-01

    Uranium deposits containing molybdenum and fluorite occur in the Central Mining Area, near Marysvale, Utah, and formed in an epithermal vein system that is part of a volcanic/hypabyssal complex. They represent a known, but uncommon, type of deposit; relative to other commonly described volcanic-related uranium deposits, they are young, well-exposed and well-documented. Hydrothermal uranium-bearing quartz and fluorite veins are exposed over a 300 m vertical range in the mines. Molybdenum, as jordisite (amorphous MoS2, together with fluorite and pyrite, increase with depth, and uranium decreases with depth. The veins cut 23-Ma quartz monzonite, 20-Ma granite, and 19-Ma rhyolite ash-flow tuff. The veins formed at 19-18 Ma in a 1 km2 area, above a cupola of a composite, recurrent, magma chamber at least 24 ?? 5 km across that fed a sequence of 21- to 14-Ma hypabyssal granitic stocks, rhyolite lava flows, ash-flow tuffs, and volcanic domes. Formation of the Central Mining Area began when the intrusion of a rhyolite stock, and related molybdenite-bearing, uranium-rich, glassy rhyolite dikes, lifted the fractured roof above the stock. A breccia pipe formed and relieved magmatic pressures, and as blocks of the fractured roof began to settle back in place, flat-lying, concave-downward, 'pull-apart' fractures were formed. Uranium-bearing, quartz and fluorite veins were deposited by a shallow hydrothermal system in the disarticulated carapace. The veins, which filled open spaces along the high-angle fault zones and flat-lying fractures, were deposited within 115 m of the ground surface above the concealed rhyolite stock. Hydrothermal fluids with temperatures near 200??C, ??18OH2O ~ -1.5, ?? -1.5, ??DH2O ~ -130, log fO2 about -47 to -50, and pH about 6 to 7, permeated the fractured rocks; these fluids were rich in fluorine, molybdenum, potassium, and hydrogen sulfide, and contained uranium as fluoride complexes. The hydrothermal fluids reacted with the wallrock resulting in

  5. Hydrothermal factors in porosity evolution and caprock formation at the Geysers steam field, California--insight from the Geysers Coring Project

    SciTech Connect

    Hulen, Jeffrey B.; Nielson, Dennis L.

    1995-01-26

    The Department of Energy (DOE)/geothermal industry-sponsored Geysers Coring Project (GCP) has yielded 236.8 m of continuous core apparently spanning the transition between the uppermost Geysers steam reservoir and its caprock. Both zones in the corehole are developed in superficially similar, fractured, complexly veined and locally sericitized, Franciscan (late Mesozoic) graywacke-argillite sequences. However, whereas the reservoir rocks host two major fluid conduits (potential steam entries), the caprock is only sparingly permeable. This discrepancy appears to reflect principally vein texture and mineralogy. Two types of veins are common in the core--randomly-oriented, Franciscan metamorphic quartz-calcite veins; and high-angle, late Cenozoic veins deposited by The Geysers hydrothermal system. The older veins locally contain hydrothermal carbonate-dissolution vugs, which, although concentrated at the larger fluid conduit, are scattered throughout the core. The younger veins, commonly with intercrystalline vugs, consist dominantly of euhedral quartz, calcite, K-feldspar, wairakite, and pyrite--those in the reservoir rock also contain minor epidote and illite. The corresponding caprock veins are devoid of epidote but contain abundant, late-stage, mixed-layer illite/smecite (5-18% smectite interlayers) with minor chlorite/smectite (40-45% smectite interlayers). We suggest that clots of these two expandable clays in the caprock clog otherwise permeable veins and carbonate-dissolution networks at strategic sites to produce or enhance the seal on the underlying steam reservoir. Illite/smectite geothermometry indicates that the SB-15-D caprock clays were precipitated in the approximate temperature range 180-218 C, and those in the reservoir at about 218-238 C. These temperatures, along with occurrence of the clays on commonly etched calcite, K-feldspar, or wairakite, suggest that the clays were precipitated from mildly acidic steam condensate under conditions similar to

  6. Hydrothermal alteration, ore fluid characteristics, and gold depositional processes along a trondhjemite-komatiite contact at Tarmoola, Western Australia

    USGS Publications Warehouse

    Duuring, P.; Hagemann, S.G.; Cassidy, K.F.; Johnson, C.A.

    2004-01-01

    Tarmoola is a structurally controlled Archean orogenic gold deposit hosted in greenschist facies metamorphosed komatiite and trondhjemite in the Leonora district of the Eastern Goldfields province, Yilgarn craton. High-grade (>1 g/t Au) orebodies are located in komatiite wall rock adjacent to the eastern and northeastern margins of the asymmetrical, north-south-striking, Tarmoola trondhjemite intrusion. Gold-bearing veins post-date trondhjemite emplacement (ca. 2700 Ma), quartz diorite dikes (ca. 2667 Ma), and regional greenschist facies metamorphism. Textures and crosscutting relationships in gold-bearing veins indicate two stages of hydrothermal fluid infiltration associated with a single gold-related hydrothermal event: a volumetrically dominant, but gold-poor, stage I fluid and a gold-rich stage II fluid. Gold-bearing veins contain stage I milky quartz and pyrite that are overprinted by stage II quartz-ankerite-muscovite-chalcopyrite-sphalerite-galena-gold-tellurides ?? albite ?? chlorite ?? fuchsite ?? epidote ?? scheelite. Stage I hydrothermal alteration assemblages are different in trondhjemite and komatiite due to contrasting reactions between a common ore fluid and disparate wall-rock chemistry. Stage II fluid-wall rock interaction was minor compared to stage I and is indicated by the overprinting of stage I mineral assemblages by stage II microveins. Wall-rock alteration proximal to veins in trondhjemite is characterized by replacement of igneous plagioclase, amphibole, biotite, and metamorphic chlorite by hydrothermal quartz, muscovite, ankerite, calcite, pyrite, chalcopyrite, sphalerite, galena, tellurides, and gold, whereas in proximal alteration in komatiite, metamorphic chlorite and talc are replaced by ankerite, quartz, muscovite, albite, chlorite, fuchsite, pyrite, chalcopyrite, sphalerite, galena, tellurides, and gold. The stage II fluid was enriched in H2O, CO2, Si, Ca, K, Na, S, Au, Ag, Cu, Pb, W, Bi, As, Mo, Zn, and Te. Based on fluid inclusion

  7. Geology, alteration, age, and origin of iron oxide-apatite deposits in Upper Eocene quartz monzonite, Zanjan district, NW Iran

    NASA Astrophysics Data System (ADS)

    Nabatian, Ghasem; Ghaderi, Majid; Corfu, Fernando; Neubauer, Franz; Bernroider, Manfred; Prokofiev, Vsevolod; Honarmand, Maryam

    2014-02-01

    Iron oxide-apatite deposits are present in Upper Eocene pyroxene-quartz monzonitic rocks of the Zanjan district, northwestern Iran. Mineralization occurred in five stages: (1) deposition of disseminated magnetite and apatite in the host rock; (2) mineralization of massive and banded magnetite ores in veins and stockwork associated with minor brecciation and calcic alteration of host rocks; (3) deposition of sulfide ores together with potassic alteration; (4) formation of quartz and carbonate veins and sericite, chlorite, epidote, silica, carbonate, and tourmaline alteration; and (5) supergene alteration and weathering. U-Pb dating of monazite inclusions in the apatite indicates an age of 39.99 ± 0.24 Ma, which is nearly coeval with the time of emplacement of the host quartz monzonite, supporting the genetic connection. Fluid inclusions in the apatite have homogenization temperatures of about 300 °C and oxygen isotopic compositions of the magnetite support precipitation from magmatic fluids. Late-stage quartz resulted from the introduction of a cooler, less saline, and isotopically depleted fluid. The iron oxide-apatite deposits in the Tarom area of the Zanjan district are typical of a magmatic-hydrothermal origin and are similar to the Kiruna-type deposits with respect to mineral assemblages, fabric and structure of the iron ores, occurrence of the ore bodies, and wall rock alteration.

  8. Hydrothermal alteration in metasedimentary rock-hosted orogenic gold deposits, Reefton goldfield, South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Christie, Anthony B.; Brathwaite, Robert L.

    2003-01-01

    Orogenic or mesothermal quartz lodes in lower Palaeozoic Greenland Group metasedimentary rocks of the Reefton area have produced 67 tonnes (t) of gold prior to 1951, and recent exploration has identified new gold resources in several deposits, including the largest past producers, Blackwater and Globe-Progress. The metasedimentary rocks consist of alternating sandstone and mudstone beds that were metamorphosed to lower greenschist facies prior to being hydrothermally altered adjacent to the quartz lodes. The sandstones are feldspathic litharenites averaging Q65-F10-R25, with detrital grains of quartz, rock fragments, muscovite, and plagioclase and biotite that were altered to albite and chlorite, respectively, during metamorphism. Accessory minerals are graphite, apatite, zircon, tourmaline and titanite. Hydrothermal alteration of the sandstones has developed a mineral assemblage of K-mica, carbonate (dolomite, ankerite, ferroan magnesite and magnesian siderite), chlorite, pyrite and arsenopyrite. The abundance of hydrothermal chlorite is greater at Blackwater than at the other prospects studied. Hydrothermal alteration associated with the quartz lodes is marked by bleaching, magnesian siderite spots, disseminated arsenopyrite and pyrite and thin carbonate, quartz and sulphide veins. These trends are accompanied by increasing concentrations of S, As and Sb and decreasing Na, and a decrease of Fe and Mg in K-mica. The alkali alteration indices 3K/Al (representing K-mica) and Na/Al (representing albite) generally show antipathetic trends, with 3K/Al increasing near the lodes and Na/Al decreasing. These trends reflect the replacement of albite by K-mica. Carbonate alteration indices CO2/(Ca + Mg +Fe) and CO2/[Ca + Mg + Fe -0.5(S + As)] quantify the abundance of hydrothermal carbonates, but they show variable correlation with the lodes. They increase the width of the alteration halo in the hanging wall of the lodes at the Globe-Progress and General Gordon prospects

  9. Shallow Hydrothermal Flow in a Strike-Slip Fault System, Mt Isa, Australia: A Proterozoic Analog for Modern Geothermal Systems Along Strike-Slip Faults

    NASA Astrophysics Data System (ADS)

    Sibson, R. H.; Ghisetti, F.; Begbie, M.

    2014-12-01

    Strong E-W shortening during the Isan Orogeny (1590-1500 Ma) led to crustal thickening and compressional inversion of former intracontinental rift basins. The resulting metamorphic/plutonic basement complex is disrupted by conjugate, mutually cross-cutting sets of brittle, late-orogenic strike-slip faults. Dextral strike-slip faults (separations < 25 km) strike NE-NNE, while conjugate sinistral faults strike SE-SSE, defining a wrench regime (σv = σ2) with horizontal maximum compression, σ1, trending c. 100°. The strike-slip faults are recessive except in dilational sites where upwelling hydrothermal fluids have silicified the cataclastic shear zones (CSZ) which protrude as blade-like ridges extending for kilometres across the semi-arid terrain. The mineralized fault segments include sinuous releasing bends where the fault trace is deflected <10° as well as more abrupt dilational stepovers with distributed extension fracturing linking en echelon fault segments. Other components of structural permeability include: (1) innumerable fault-parallel quartz-veins (cm to m thickness) within the CSZ; (2) irregular stringer veins; and (3) a regional set of predominantly extensional, subvertical planar quartz veins oriented 080-120° at moderate angles to the main faults. Broad contemporaneity is indicated by mutual cross-cutting relationships between all structural components. Measured strike separations along shear fractures are consistent with seismic slip increments which refreshed fracture permeability and promoted hydrothermal flow. Textures suggest the faults were exhumed from epithermal boiling environments (<1-2 km depth). Restoration of fault cohesive strength by hydrothermal cementation was critical in allowing continued vein formation by hydraulic extension fracturing. The distribution of hydrothermal quartz within the fault system provides a guide to structural localization of upflow zones in geothermal fields developed along strike-slip faults.

  10. Shock metamorphism of deformed quartz

    NASA Technical Reports Server (NTRS)

    Gratz, Andrew J.; Christie, John; Tyburczy, James; Ahrens, Thomas; Pongratz, Peter

    1988-01-01

    The effect produced by shock loading (to peak pressures of 12 and 24) on deformed synthetic quartz containing a dislocation and abundant bubbles and small inclusions was investigated, and the relationships between preexisting dislocation density shock lamellae in the target material were examined. The resultant material was found to be inhomogeneously deformed and extremely fractured. Results of TEM examinations indicate that no change in dislocation density was caused by shock loading except in regions containing shock lamellae, where the dislocation density was lowered. The shock-induced defects tend to nucleate on and be controlled by preexisting stress concentrators; shock lamellae, glassy veins, and most curviplanar defects form in tension, presumably during release. An extremely mobile silica fluid is formed and injected into fractures during release, which forcibly removes crystalline fragments from vein walls. It is concluded that shock deformation in quartz is dominated by fracture and melting.

  11. Lithogeochemistry and fluid inclusions of an Au-Ag vein deposit in a granodiorite intrusive

    SciTech Connect

    Hahn, R.; Ikramuddin, M.

    1985-01-01

    Forty-eight samples of altered and unaltered rocks and quartz veins from the Acme mine in northeast Washington, an Au-Ag vein deposit in a granodiorite intrusive, have been analyzed for SiO/sub 2/, Al/sub 2/O/sub 3/, Fe/sub 2/O/sub 3/, Feo, MgO, CaO, Na/sub 2/O, K/sub 2/O, TiO/sub 2/, MnO, P/sub 2/O/sub 5/, H/sub 2/O, CO/sub 2/, Ag, Au, Ba, Cu, Pb, Rb, Sr, Tl, and Zn. A comparison of major and trace elements shows that the altered granodiorite is enriched in SiO/sub 2/, Fe/sub 2/O/sub 3/, K/sub 2/O, Ag, Au, Ba, Cu, Pb, Rb, Tl, and Zn and depleted in Al/sub 2/O/sub 3/, FeO, MgO, CaO, Na/sub 2/O, TiO/sub 2/, MnO, P/sub 2/O/sub 5/, and Sr. The average contents of Au in unaltered and altered granodiorite and quartz veins are 9 ppb. 270 ppb and 1020 ppb respectively. The average Ba/Tl ratio in the altered samples decrease and average Rb/Sr and Tl/Sr ratios increase. K, Rb, and Tl are enriched in the altered granodiorite by factors of 1.5, 1.6, and 1.4 respectively. Tl is not enriched relative to Rb and K in the altered samples due to the high temperature of the deposit. The Ba/Tl, K/Tl and K/Rb ratios do not show complete separation of altered from unaltered samples. However, the Ba/Tl and K/Tl ratios in the quartz vein are significantly lower than the unaltered and altered granodiorite. This is due to the enrichment of Tl over K and Rb in the quartz veins. The Rb/Sr and Tl/Sr ratios are higher in the altered granodiorite and quartz veins compared to unaltered samples. The enrichment of Tl and presence of low Ba/Tl and high Rb/Sr and Tl/Sr ratios in a granodiorite indicate that the rocks are hydrothermally altered and represent a possible Au-Ag target.

  12. Age and origin of base and precious metal veins of the Coeur d'Alene mining district, Idaho

    USGS Publications Warehouse

    Fleck, R.J.; Criss, R.E.; Eaton, G.F.; Cleland, R.W.; Wavra, C.S.; Bond, W.D.

    2002-01-01

    Ore-bearing quartz-carbonate veins of the Coeur d'Alene mining district yield 87Sr/86Sr ratios of 0.74 to >1.60 for low Rb/Sr, carbonate gangue minerals, similar to current ranges measured in Middle Proterozoic, high Rb/Sr rocks of the Belt Supergroup. Stable isotope and fluid inclusion studies establish a genetic relationship between vein formation and metamorphic-hydrothermal systems of the region. These extraordinary 87Sr/86Sr ratios require accumulation of radiogenic 87Sr in a high Rb/Sr system over an extended period prior to incorporation of Sr into the hydrothermal veins. Evaluation of the age and composition of potential sources of highly radiogenic Sr indicates that the ore-bearing veins of the Coeur d'Alene district formed during the Cretaceous from components scavenged from rocks of the Belt Supergroup, the primary host rocks of the district. Proterozoic Pb isotope ratios observed in galena from many Coeur d'Alene veins were established when Pb separated from uranium during deposition or diagenesis of the Belt Supergroup at 1400 to 1500 Ma, possibly as disseminated syngenetic deposits. K-Ar and Rb-Sr apparent ages and ??18O values of Belt Supergroup rocks decrease from the Coeur d'Alene district toward the Idaho and Kaniksu batholiths, approximately normal to the trends of metamorphic isograds, fold axes, foliation, and the major reverse faults of the district. Isoclinal folding, thrust faulting, high-temperature metamorphism, granitic plutonism, and regional-scale metamorphic-hydrothermal activity is documented in the region between 140 and 45 Ma, representing the only such combination of events in the Coeur d'Alene region subsequent to about 1300 Ma. The Sr and oxygen results and geologic evidence favor formation of the ore-bearing carbonate veins by fluids related to a complex metamorphic-hydrothermal system during the Cretaceous. Pb with Proterozoic isotopic compositions was probably mobilized and incorporated like other metals into the hydrothermal

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

    USGS Publications Warehouse

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

    1984-01-01

    Vein-related alteration consisting of quartz-sericite-pyrite, chloritic, argillic, and silicic halos was superimposed on broad zones of pervasive silicic, potassic, and argillic alteration that surrounds the rhyolite intrusive body. Quartz-sericite-pyrite alteration associated with the earliest stage of mineralization was followed by broad, pervasive, stratigraphically controlled potassic alteration. Subsequent mineralization was accompanied by quartz-sericitepyrite alteration and was followed by the main stage of mineralization that formed strong chloritic alteration halos. Development of broad zones and halos of argillic alteration also may have been related to the main stage of mineralization. Development of silicic halos was characteristic of the late stages of mineralization. Broad, pervasive propylitic alteration was then superimposed on all alteration types and represents cooling and inward encroachment of the hydrothermal system. All alteration, except the early silicic alteration is interpreted to have been related to circulating meteoric fluids heated by the rhyolite.

  14. Focus on Varicose Veins

    MedlinePlus

    ... Other veins often mistaken for varicose veins are spider veins and reticular veins, which are the visible ... greenish-blue veins that appear in our legs. Spider veins or teleangiectesias are tiny veins that you ...

  15. Mineralogy and stable isotope geochemistry of hydrothermally altered oceanic rocks

    USGS Publications Warehouse

    Stakes, D.S.; O'Neil, J.R.

    1982-01-01

    Mineralogical and isotopic variations observed in altered glassy and crystalline rocks from the East Pacific Rise and the Mid-Atlantic Ridge provide information about the temperatures of alteration and seawater/rock ratios for various hydrothermal regimes within the oceanic crust. A systematic increase in alteration temperature is evident for the glassy rocks in the sequence: (1) nontronite and celadonite vesicle fillings (35??C), (2) saponite-rich pillow breccias (130-170??C), (3) calcite-rich greenstone breccias and epidote-rich greenstone (200-350??C). These results include the highest temperatures thus far reported for saponite formation. The "seawater-dominated" hydrothermal alteration process that formed the saponite-rich pillow breccias is characterized by high water/rock ratios (>50:1), low to moderate temperatures, a seawater origin of most of the carbon in vein calcites (??13 C ??? 0) and the predominance of Fe-rich saponite and calcite as secondary phases. Greenstones (chlorite-quartz-epidote) and greenstone breccias (chlorite-quartz-albite-calcite) are altered in a "rock-dominated" system with lower water/rock ratios (50:1 to < 1:1), higher temperatures, and vein calcites with carbon that is principally of magmatic origin (??13 C ??? -4). The crystalline rocks (diabase, gabrro, and metagabbro) are affected to varying degrees by pervasive high-temperature seawater interactions that commence soon after solidification, producing varying proportions of fine-grained secondary minerals including talc, smectite, chlorite, vermiculite, actinolite, and sodic plagioclase. Hydrothermal solutions, derived from alteration of the crystalline rocks, are of the appropriate temperature and isotopic composition to alter the overlying glassy rocks to the observed mineralogies as well as being the source of metal-rich deposits associated with the oceanic spreading centers. ?? 1982.

  16. Hydrothermal evolution of the Sar-Cheshmeh porphyry Cu Mo deposit, Iran: Evidence from fluid inclusions

    NASA Astrophysics Data System (ADS)

    Hezarkhani, Ardeshir

    2006-12-01

    The Sar-Cheshmeh porphyry Cu-Mo deposit is located in Southwestern Iran (˜65 km southwest of Kerman City) and is associated with a composite Miocene stock, ranging in composition from diorite through granodiorite to quartz-monzonite. Field observations and petrographic studies demonstrate that the emplacement of the Sar-Cheshmeh stock took place in several pulses, each with associated hydrothermal activity. Molybdenum was concentrated at a very early stage in the evolution of the hydrothermal system and copper was concentrated later. Four main vein Groups have been identified: (I) quartz+molybdenite+anhydrite±K-feldspar with minor pyrite, chalcopyrite and bornite; (II) quartz+chalcopyrite+pyrite±molybdenite±calcite; (III) quartz+pyrite+calcite±chalcopyrite±anhydrite (gypsum)±molybdenite; (IV) quartz±calcite±gypsum±pyrite±dolomite. Early hydrothermal alteration produced a potassic assemblage (orthoclase-biotite) in the central part of the stock, propylitic alteration occurred in the peripheral parts of the stock, contemporaneously with potassic alteration, and phyllic alteration occurred later, overprinting earlier alteration. The early hydrothermal fluids are represented by high temperature (350-520 °C), high salinity (up to 61 wt% NaCl equivalent) liquid-rich fluid inclusions, and high temperature (340-570 °C), low-salinity, vapor-rich inclusions. These fluids are interpreted to represent an orthomagmatic fluid, which cooled episodically; the brines are interpreted to have caused potassic alteration and deposition of Group I and II quartz veins containing molybdenite and chalcopyrite. Propylitic alteration is attributed to a liquid-rich, lower temperature (220-310 °C), Ca-rich, evolved meteoric fluid. Influx of meteoric water into the central part of the system and mixing with magmatic fluid produced albitization at depth and shallow phyllic alteration. This influx also caused the dissolution of early-formed copper sulphides and the remobilization of

  17. Chabazite in spodumene-bearing Alpine-type fissure veins from Hiddenite, North Carolina, USA

    NASA Astrophysics Data System (ADS)

    Wise, Michael A.

    2009-07-01

    Alpine-type fissure vein mineralization in the Hiddenite area of western North Carolina, USA consists mostly of quartz, but locally contains Cr-bearing beryl (emerald) or Cr-bearing spodumene (hiddenite). These gem minerals occur in mineral-lined cavities and may be accompanied by euhedral crystals of quartz, calcite, muscovite, rutile, albite, pyrite, siderite and dolomite. Chabazite-Ca occurs as a late stage phase in spodumene-bearing veins, but is absent in emerald-bearing veins. Chabazite-Ca occurs as simple penetrating twins of pseudocubic rhombohedra and as the lens-shaped variety, phacolite. Chabazite-Ca from Hiddenite contains minor amounts of Na, Mg, Fe and K. Phacolitic chabazite-Ca shows Fe-enriched but Mg-depleted cores relative to the rims. Chemical zoning is absent in rhombohedral chabazite. The Hiddenite chabazite apparently precipitated under low temperature (< 250°C) and low pressure (< 2 kbar) conditions during the waning stages of crystallization of an alkaline hydrothermal fluid.

  18. Raman and micro-thermometric investigation of the fluid inclusions in quartz in a gold-rich formation from Lepaguare mining district (Honduras, Central America).

    PubMed

    Bersani, D; Salvioli-Mariani, E; Mattioli, M; Menichetti, M; Lottici, P P

    2009-08-01

    Fluid inclusions in the quartz crystals present in gold-rich veins from central Honduras have been studied by means of micro-thermometry and micro-Raman spectroscopy in order to provide information on the physico-chemical conditions and chemical composition of the mineralizing fluids. The use of a confocal micro-Raman apparatus allowed to obtain information on the fluid composition, in particular on the gas phase, minimizing the contributions of the host matrix to the Raman signal. The samples studied were collected from an area (Lepaguare mining district, Northern-Central Honduras) rich in ore deposits due to the Cenozoic magmatic activity, where the gold and sulphide mineralization is connected with a system of quartz veins (few decimetres thick) occurring in low-grade metamorphic rocks and produced by hydrothermal fluids. The quartz crystals present in the gold-rich veins often contain fluid inclusions. Four types of fluid inclusions have been observed, but their assemblage in the same clusters and fracture systems, as well as their comparable salinity and homogenization data, suggest that they have the same origin. Micro-thermometry and Raman spectroscopy provide a composition of the mineralizing fluids attributable to the system H(2)O-NaCl-KCl-CO(2)-CH(4), with temperature and pressure intervals of 210-413 degrees C and 1050-3850 bar, respectively. These data agree with an epigenetic origin of the gold deposit (depth < 6 km) related to granitoid or granodiorite intrusions associated to orogenic environments. PMID:19117796

  19. AGE AND ORIGIN OF BASE- AND PRECIOUS-METAL VEINS OF THE COEUR D'ALENE MINING DISTRICT, IDAHO

    SciTech Connect

    Fleck, R J; Criss, R E; Eaton, G F; Cleland, R W; Wavra, C S; Bond, W D

    2000-11-07

    Ore-bearing quartz-carbonate veins of the Coeur d'Alene mining district yield {sup 87}Sr/{sup 86}Sr ratios of 0.74 to >1.60 for low-Rb/Sr, carbonate gangue minerals, similar to current ranges measured in Middle Proterozoic, high-Rb/Sr rocks of the Belt Supergroup. Stable-isotope and fluid-inclusion studies establish a genetic relationship between vein formation and metamorphic-hydrothermal systems of the region. These extraordinary {sup 87}Sr/{sup 86}Sr ratios require accumulation of radiogenic {sup 87}Sr in a high Rb/Sr system over an extended period prior to incorporation of Sr into the veins by hydrothermal processes. Evaluation of the age and composition of potential sources of highly radiogenic Sr indicates that the ore-bearing veins of the Coeur d'Alene district formed within the last 200 Ma from components scavenged from sedimentary and metasedimentary rocks of the Belt Supergroup, the primary host-rocks of the district. These results are consistent with a Cretaceous or Early Tertiary age for these veins. Pb-Zn deposits that yield Pb isotope, K-Ar, and Ar-Ar results indicative of a Proterozoic age probably formed during deposition or diagenesis of the Belt Supergroup at 1350-1500 Ma, possibly as Sullivan-type syngenetic deposits. K-Ar and Rb-Sr apparent ages and {delta}{sup 18}O values of Belt Supergroup rocks decrease southward from the Coeur d'Alene district toward the Idaho batholith, normal to the trends of metamorphic isograds, fold axes, foliation, and the major reverse faults of the district. Isoclinal folding, thrust faulting, high-temperature metamorphism, granitic plutonism, and regional-scale metamorphic-hydrothermal activity is documented in the region between 140 Ma and 45 Ma, but no similar combination of events is recognized for Late Proterozoic time. Combined with Sr results from the veins, the evidence strongly favors formation of the ore-bearing carbonate veins of the district by fluids related to a complex metamorphic-hydrothermal system

  20. What Causes Varicose Veins?

    MedlinePlus

    ... page from the NHLBI on Twitter. What Causes Varicose Veins? Weak or damaged valves in the veins can ... space. These are varicose veins. Normal Vein and Varicose Vein Figure A shows a normal vein with a ...

  1. Stratigraphic development and hydrothermal activity in the central western Cascade Range, Oregon

    SciTech Connect

    Cummings, M.L.; Bull, M.K. ); Pollock, J.M. ); Thompson, G.D. )

    1990-11-10

    Two volcanic sequences bounded by erosional unconformities compose the stratigraphy of the North Santiam mining district, Western Cascade Range, Oregon. Diorite, grandodiorite, and leucocratic quartz porphyry dikes, stocks, and sills intrude the breccias, flows, and tuffs of a volcanic center in the older Sardine Formation. Tourmaline-bearing breccia pipes are associated with the porphyritic granodiorite intrusions. An erosional unconformity separates the Sardine Formation from the overlying Elk Lake formation. The alteration patterns in the two formations are consistent with the development of hydrothermal systems during the eruption of each formation. However, the development of the two hydrothermal systems is separated by a period of erosion of the older volcanic pile. Early formation of mineralization that resembles porphyry copper deposits occurred within the Sardine Formation, and later, after eruption of the Elk Lake formation, epithermal veins and alteration developed along faults, fractures, and the margins of dikes in the Sardine Formation.

  2. Timing of porphyry (Cu-Mo) and base metal (Zn-Pb-Ag-Cu) mineralisation in a magmatic-hydrothermal system—Morococha district, Peru

    NASA Astrophysics Data System (ADS)

    Catchpole, Honza; Kouzmanov, Kalin; Bendezú, Aldo; Ovtcharova, Maria; Spikings, Richard; Stein, Holly; Fontboté, Lluís

    2015-12-01

    The Morococha district in central Peru is characterised by economically important Cordilleran polymetallic (Zn-Pb-Ag-Cu) vein and replacement bodies and the large Toromocho porphyry Cu-Mo deposit in its centre. U-Pb, Re-Os, and 40Ar/39Ar geochronology data for various porphyry-related hydrothermal mineralisation styles record a 3.5-Ma multi-stage history of magmatic-hydrothermal activity in the district. In the late Miocene, three individual magmatic-hydrothermal centres were active: the Codiciada, Toromocho, and Ticlio centres, each separated in time and space. The Codiciada centre is the oldest magmatic-hydrothermal system in the district and consists of a composite porphyry stock associated with anhydrous skarn and quartz-molybdenite veins. The hydrothermal events are recorded by a titanite U-Pb age at 9.3 ± 0.2 Ma and a molybdenite Re-Os age at 9.26 ± 0.03 Ma. These ages are indistinguishable from zircon U-Pb ages for porphyry intrusions of the composite stock and indicate a time span of 0.2 Ma for magmatic-hydrothermal activity. The small Ticlio magmatic-hydrothermal centre in the west of the district has a maximum duration of 0.3 Ma, ranging from porphyry emplacement to porphyry mineralisation at 8.04 ± 0.14 Ma (40Ar/39Ar muscovite cooling age). The Toromocho magmatic-hydrothermal centre has a minimum of five recorded porphyry intrusions that span a total of 1.3 Ma and is responsible for the formation of the giant Toromocho Cu-Mo deposit. At least two hydrothermal pulses are identified. Post-dating a first pulse of molybdenite mineralisation, wide-spread hydrous skarn covers an area of over 6 km2 and is recorded by five 40Ar/39Ar cooling ages at 7.2-6.8 Ma. These ages mark the end of the slowly cooling and long-lived Toromocho magmatic-hydrothermal centre soon after last magmatic activity at 7.26 ± 0.02 Ma. District-wide (50 km2) Cordilleran base metal vein and replacement bodies post-date the youngest recorded porphyry mineralisation event at Toromocho

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

    NASA Astrophysics Data System (ADS)

    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 (< 3 m) halos of illite and illite/smectite next to veins, grading outward into 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

  4. Quartz ball value

    NASA Technical Reports Server (NTRS)

    Goetz, C.; Ingle, W. M.

    1979-01-01

    Quartz ball valve consisting of two quartz joints sealed back-to-back and seated in quartz sockets perform at temperatures of up to 1,250 C and in corrosive chemical environments without contamination or degradation.

  5. Fluid inclusion and stable isotopes studies of epithermal gold-bearing veins in the SE Afar Rift (Djibouti)

    NASA Astrophysics Data System (ADS)

    Moussa, N.; Boiron, M. C.; Grassineau, N.; Fouquet, Y.; Le Gall, B.; Mohamed, J.

    2015-12-01

    The Afar rift results from the interaction of a number of actively-propagating tectono-magmatic axes. Recent field investigations in the SE Afar rift have emphasized the importance of hydrothermal system in rift-related volcanic complexes. Mineralization occur as gold-silver bearing veins and are associated with felsic volcanism. Late carbonate veins barren of sulfides and gold are common. The morphologies and textures of quartz show crustiform colloform banding, massive and breccias. Microthermometric measurements were made on quartz-hosted two phases (liquid + vapor) inclusions; mean homogenization temperature range from 150°C to 340°C and ice-melting temperatures range from -0.2° to 1.6°C indicating that inclusion solutions are dilute and contain 0.35 to 2.7 equivalent wt. % NaCl. Furthermore, δ18O and δ13C values from calcite range from 3.7 to 26.6 ‰ and -7.5 to 0.3‰, respectively. The presence of platy calcite and adularia indicate that boiling condition existed. This study shows that precious-metal deposition mainly occurred from hydrothermal fluids at 200°C at around 300 and 450 m below the present-day surface in a typical low-sulphidation epithermal environment.

  6. The interplay of evolved seawater and magmatic-hydrothermal fluids in the 3.24 Ga panorama volcanic-hosted massive sulfide hydrothermal system, North Pilbara Craton, Western Australia

    USGS Publications Warehouse

    Drieberg, Susan L.; Hagemann, Steffen G.; Huston, David L.; Landis, Gary; Ryan, Chris G.; Van Achterbergh, Esmé; Vennemann, Torsten

    2013-01-01

    The ~3240 Ma Panorama volcanic-hosted massive sulfide (VHMS) district is unusual for its high degree of exposure and low degree of postdepositional modification. In addition to typical seafloor VHMS deposits, this district contains greisen- and vein-hosted Mo-Cu-Zn-Sn mineral occurrences that are contemporaneous with VHMS orebodies and are hosted by the Strelley granite complex, which also drove VHMS circulation. Hence the Panorama district is a natural laboratory to investigate the role of magmatic-hydrothermal fluids in VHMS hydrothermal systems. Regional and proximal high-temperature alteration zones in volcanic rocks underlying the VHMS deposits are dominated by chlorite-quartz ± albite assemblages, with lesser low-temperature sericite-quartz ± K-feldspar assemblages. These assemblages are typical of VHMS hydrothermal systems. In contrast, the alteration assemblages associated with granite-hosted greisens and veins include quartz-topaz-muscovite-fluorite and quartz-muscovite (sericite)-chlorite-ankerite. These vein systems generally do not extend into the overlying volcanic pile. Fluid inclusion and stable isotope studies suggest that the greisens were produced by high-temperature (~590°C), high-salinity (38–56 wt % NaCl equiv) fluids with high densities (>1.3 g/cm3) and high δ18O (9.3 ± 0.6‰). These fluids are compatible with the measured characteristics of magmatic fluids evolved from the Strelley granite complex. In contrast, fluids in the volcanic pile (including the VHMS ore-forming fluids) were of lower temperature (90°–270°C), lower salinity (5.0–11.2 wt % NaCl equiv), with lower densities (0.88–1.01 g/cm3) and lower δ18O (−0.8 ± 2.6‰). These fluids are compatible with evolved Paleoarchean seawater. Fluids that formed the quartz-chalcopyrite-sphalerite-cassiterite veins, which are present within the granite complex near the contact with the volcanic pile, were intermediate in temperature and isotopic composition between the greisen

  7. A Hydrothermal System Associated with the Siljan Impact Structure, Sweden-Implications for the Search for Fossil Life on Mars

    NASA Astrophysics Data System (ADS)

    Hode, Tomas; von Dalwigk, Ilka; Broman, Curt

    2003-06-01

    The Siljan ring structure (368 +/- 1.1 Ma) is the largest known impact structure in Europe. It is a 65-km-wide, eroded, complex impact structure, displaying several structural units, including a central uplifted region surrounded by a ring-shaped depression. Associated with the impact crater are traces of a post-impact hydrothermal system indicated by precipitated and altered hydrothermal mineral assemblages. Precipitated hydrothermal minerals include quartz veins and breccia fillings associated with granitic rocks at the outer margin of the central uplift, and calcite, fluorite, galena, and sphalerite veins associated with Paleozoic carbonate rocks located outside the central uplift. Two-phase water/gas and oil/gas inclusions in calcite and fluorite display homogenization temperatures between 75°C and 137°C. With an estimated erosional unloading of ~1 km, the formation temperatures were probably not more than 10-15°C higher. Fluid inclusion ice-melting temperatures indicate a very low salt content, reducing the probability that the mineralization was precipitated during the Caledonian Orogeny. Our findings suggest that large impacts induce low-temperature hydrothermal systems that may be habitats for thermophilic organisms. Large impact structures on Mars may therefore be suitable targets in the search for fossil thermophilic organisms.

  8. Weathering of post-impact hydrothermal deposits from the Haughton impact structure: implications for microbial colonization and biosignature preservation.

    PubMed

    Izawa, M R M; Banerjee, Neil R; Osinski, G R; Flemming, R L; Parnell, J; Cockell, C S

    2011-01-01

    Meteorite impacts are among the very few processes common to all planetary bodies with solid surfaces. Among the effects of impact on water-bearing targets is the formation of post-impact hydrothermal systems and associated mineral deposits. The Haughton impact structure (Devon Island, Nunavut, Canada, 75.2 °N, 89.5 °W) hosts a variety of hydrothermal mineral deposits that preserve assemblages of primary hydrothermal minerals commonly associated with secondary oxidative/hydrous weathering products. Hydrothermal mineral deposits at Haughton include intra-breccia calcite-marcasite vugs, small intra-breccia calcite or quartz vugs, intra-breccia gypsum megacryst vugs, hydrothermal pipe structures and associated surface "gossans," banded Fe-oxyhydroxide deposits, and calcite and quartz veins and coatings in shattered target rocks. Of particular importance are sulfide-rich deposits and their associated assemblage of weathering products. Hydrothermal mineral assemblages were characterized structurally, texturally, and geochemically with X-ray diffraction, micro X-ray diffraction, optical and electron microscopy, and inductively coupled plasma atomic emission spectroscopy. Primary sulfides (marcasite and pyrite) are commonly associated with alteration minerals, including jarosite (K,Na,H(3)O)Fe(3)(SO(4))(2)(OH)(6), rozenite FeSO(4)·4(H(2)O), copiapite (Fe,Mg)Fe(4)(SO(4))(6)(OH)(2)·20(H(2)O), fibroferrite Fe(SO(4))(OH)·5(H(2)O), melanterite FeSO(4)·7(H(2)O), szomolnokite FeSO(4)·H(2)O, goethite α-FeO(OH), lepidocrocite γ-FeO(OH) and ferrihydrite Fe(2)O(3)·0.5(H(2)O). These alteration assemblages are consistent with geochemical conditions that were locally very different from the predominantly circumneutral, carbonate-buffered environment at Haughton. Mineral assemblages associated with primary hydrothermal activity, and the weathering products of such deposits, provide constraints on possible microbial activity in the post-impact environment. The initial period of

  9. Vein Problems Related to Varicose Veins

    MedlinePlus

    ... your doctor if you think you have them. Spider Veins Spider veins are a smaller version of varicose veins and a less serious type of telangiectasias. Spider veins involve the capillaries, the smallest blood vessels ...

  10. Hydrothermal alteration in basalts from Vargeão impact structure, south Brazil, and implications for recognition of impact-induced hydrothermalism on Mars

    NASA Astrophysics Data System (ADS)

    Yokoyama, Elder; Nédélec, Anne; Baratoux, David; Trindade, Ricardo I. F.; Fabre, Sébastien; Berger, Gilles

    2015-05-01

    The 12-km-wide Vargeão impact structure was formed 123 Myr ago in the Paraná basaltic province (southern Brazil). At this time the province region had a dry climate, although a large brackish aquifer had been formed in the underlying sandstones. It is therefore one of the best terrestrial analogs for studying impact-related products on a dry martian surface environment with preserved ice-rich ground. The basalts within the impact structure display cm-sized breccia veins filled with lithic clasts, glassy remnants, newly formed Fe-oxyhydroxides and secondary phases, such as calcite, phyllosilicates and, subordinately quartz and zeolite. The textural and mineralogical study of these phases demonstrate their hydrothermal origin. Although the very center of the structure has experienced the highest pressures and temperatures, the most developed hydrothermal changes are recognized in an inner collar surrounding the central depression. This inner collar is also the location of major modifications of the rock magnetic properties. These magnetic signatures are related to the distribution of impact-related faults and to the formation of new iron oxides. Geochemical modeling indicate that hydrothermal phases formation required low water/rock ratios. Our observations therefore suggest that hydrothermal alteration took place following the perturbation of the aquifer by the impact, but evidence for hydrothermal circulation is limited in comparison with other impact-related hydrothermal systems. This situation may be explained by the presence of the aquifer below the heat source, such a setting being exceptional for the Earth, but common on Mars. However, the spectroscopic signatures in visible/near infrared images suggest that this kind of impact-related hydrothermal alteration may be still indentified in large impact craters on Mars by orbital instruments. These results does not exclude the possibility that more developed alteration took place in breccias that are today

  11. Fluid-inclusion microthermometry and the Zr-in-rutile thermometer for hydrothermal rutile

    NASA Astrophysics Data System (ADS)

    Cabral, Alexandre Raphael; Rios, Francisco Javier; de Oliveira, Lucilia Aparecida Ramos; de Abreu, Francisco Robério; Lehmann, Bernd; Zack, Thomas; Laufek, František

    2015-03-01

    The Zr-in-rutile thermometer is well established for the determination of metamorphic temperatures, particularly in high-grade metamorphic terrains, and for sedimentary provenance studies. The robustness of the rutile thermometry has not been tested on hydrothermal systems. Unlike quartz, a common hydrothermal mineral with abundant fluid inclusions, it is difficult to find fluid inclusions in rutile that are suitable for fluid-inclusion microthermometry. Here, we report fluid-inclusion microthermometric measurements in rutile from the auriferous quartz-kaolinite-hematite vein that typifies the gold deposit of Mil Oitavas in the southern Serra do Espinhaço, Minas Gerais, Brazil. Primary fluid inclusions in the rutile record moderately saline (10-12 wt% NaCl equivalent), aqueous-carbonic fluids with a total homogenization temperature of ~250 °C, which were likely trapped at about 300 °C and 2.0 kbar. This temperature is approximately 200 °C lower than that predicted by the Zr-in-rutile thermometer. For hydrothermal conditions of relatively low temperature, direct measurements of homogenization temperatures in rutile-hosted fluid inclusions should be preferred to the Zr-in-rutile thermometer.

  12. 43 CFR 3864.1-3 - Millsites for quartz mills or reduction works.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Millsites for quartz mills or reduction... APPLICATIONS Millsite Patents § 3864.1-3 Millsites for quartz mills or reduction works. In case the owner of a quartz mill or reduction works is not the owner or claimant of a vein or lode claim the law permits...

  13. 43 CFR 3864.1-3 - Millsites for quartz mills or reduction works.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Millsites for quartz mills or reduction... APPLICATIONS Millsite Patents § 3864.1-3 Millsites for quartz mills or reduction works. In case the owner of a quartz mill or reduction works is not the owner or claimant of a vein or lode claim the law permits...

  14. 43 CFR 3864.1-3 - Millsites for quartz mills or reduction works.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Millsites for quartz mills or reduction... APPLICATIONS Millsite Patents § 3864.1-3 Millsites for quartz mills or reduction works. In case the owner of a quartz mill or reduction works is not the owner or claimant of a vein or lode claim the law permits...

  15. 43 CFR 3864.1-3 - Millsites for quartz mills or reduction works.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Millsites for quartz mills or reduction... APPLICATIONS Millsite Patents § 3864.1-3 Millsites for quartz mills or reduction works. In case the owner of a quartz mill or reduction works is not the owner or claimant of a vein or lode claim the law permits...

  16. Gold Veins near Great Falls, Maryland

    USGS Publications Warehouse

    Reed, John Calvin, Jr.; Reed, John C.

    1969-01-01

    Small deposits of native gold are present along an anastomosing system of quartz veins and shear zones just east of Great Falls, Montgomery County, Md. The deposits were discovered in 1861 and were worked sporadically until 1951, yielding more than 5,000 ounces of gold. The vein system and the principal veins within it strike a few degrees west of north, at an appreciable angle to foliation and fold axial planes in enclosing rocks of the Wissahickon Formation of late Precambrian (?) age. The veins cut granitic rocks of Devonian or pre-Devonian age and may be as young as Triassic. Further development of the deposits is unlikely under present economic conditions because of their generally low gold content and because much of the vein system lies on park property, but study of the Great Falls vein system may be useful in the search for similar deposits elsewhere in the Appalachian Piedmont.

  17. Mass change calculations of hydrothermal alterations within the volcanogenic metasediments hosted Cu-Pb (-Zn) mineralization at Halilar area, NW Turkey

    NASA Astrophysics Data System (ADS)

    Kiran Yildirim, Demet; Abdelnasser, Amr; Doner, Zeynep; Kumral, Mustafa

    2016-04-01

    The Halilar Cu-Pb (-Zn) mineralization that is formed in the volcanogenic metasediments of Bagcagiz Formation at Balikesir province, NW Turkey, represents locally vein-type deposit as well as restricted to fault gouge zone directed NE-SW along with the lower boundary of Bagcagiz Formation and Duztarla granitic intrusion in the study area. Furthermore, This granite is traversed by numerous mineralized sheeted vein systems, which locally transgress into the surrounding metasediments. Therefore, this mineralization closely associated with intense hydrothermal alteration within brecciation, and quartz stockwork veining. The ore mineral assemblage includes chalcopyrite, galena, and some sphalerite with covellite and goethite formed during three phases of mineralization (pre-ore, main ore, and supergene) within an abundant gangue of quartz and calcite. The geologic and field relationships, petrographic and mineralogical studies reveal two alteration zones occurred with the Cu-Pb (-Zn) mineralization along the contact between the Bagcagiz Formation and Duztarla granite; pervasive phyllic alteration (quartz, sericite, and pyrite), and selective propylitic alteration (albite, calcite, epidote, sericite and/or chlorite). This work, by using the mass balance calculations, reports the mass/volume changes (gain and loss) of the chemical components of the hydrothermal alteration zones associated with Halilar Cu-Pb (-Zn) mineralization at Balikesir area (Turkey). It revealed that the phyllic alteration has enrichments of Si, Fe, K, Ba, and LOI with depletion of Mg, Ca, and Na reflect sericitization of alkali feldspar and destruction of ferromagnesian minerals. This zone has high Cu and Pb with Zn contents represents the main mineralized zone. On the other hand, the propylitic zone is characterized by addition of Ca, Na, K, Ti, P, and Ba with LOI and Cu (lower content) referring to the replacement of plagioclase and ferromagnesian minerals by albite, calcite, epidote, and sericite

  18. Reconstructing the oxygen isotope composition of late Cambrian and Cretaceous hydrothermal vent fluid

    NASA Astrophysics Data System (ADS)

    Turchyn, Alexandra V.; Alt, Jeffrey C.; Brown, Shaun T.; DePaolo, Donald J.; Coggon, Rosalind M.; Chi, Guoxiang; Bédard, Jean H.; Skulski, Thomas

    2013-12-01

    Oxygen isotope analyses (δ18O) of 16 quartz-epidote pairs from late Cambrian (Betts Cove and Mings Bight, Newfoundland), Ordovician (Thetford Mines, Québec, Canada) and Cretaceous (Troodos, Cyprus) ophiolites are used to calculate the δ18O of the hydrothermal fluids from which they crystallized. We combine these with 3 quartz-fluid inclusion measurements and 3 quartz-magnetite measurements from the Cambrian ophiolites to explore how the range in the δ18O of submarine hydrothermal vent fluid has varied between the late Cambrian, Cretaceous and today. The range of calculated δ18O values of vent fluid (-4 to +7.4) is larger than that of modern seafloor hydrothermal vent fluid (0 to +4). We employ two numerical models to ascertain whether this range is most consistent with changes in paleo-seawater δ18O or with changes in the reactive flow path in ancient hydrothermal systems. A static calculation of the vent fluid oxygen isotope composition as a function of the water-rock ratio suggests that in an ocean with a lower δ18O than today, the range of vent fluid δ18O should be larger. Our data, however, show little evidence that the δ18O of the ocean was much lower than the global ice-free value of -1.2. A dual porosity model for reactive flow through fractured and porous media is used to model the relative evolution of the 87Sr/86Sr and δ18O of vent fluid in contact with rock. Our 87Sr/86Sr and δ18O for Cretaceous epidotes suggest the strontium concentration of the Cretaceous oceans may have been much higher than at present. The 87Sr/86Sr and δ18O data from Cambrian epidotes are strikingly different from the younger samples, and are difficult to model unless fluid-rock interaction in the Cambrian hydrothermal systems was substantially different. It is also possible that some of the quartz-epidote veins have been reset by obduction-related metamorphism. Our data suggest that the high calcium-to-sulfate ratio in early (and Cretaceous) seawater may have affected

  19. Paired stable isotopes (O, C) and clumped isotope thermometry of magnesite and silica veins in the New Caledonia Peridotite Nappe

    NASA Astrophysics Data System (ADS)

    Quesnel, Benoît; Boulvais, Philippe; Gautier, Pierre; Cathelineau, Michel; John, Cédric M.; Dierick, Malorie; Agrinier, Pierre; Drouillet, Maxime

    2016-06-01

    The stable isotope compositions of veins provide information on the conditions of fluid-rock interaction and on the origin of fluids and temperatures. In New Caledonia, magnesite and silica veins occur throughout the Peridotite Nappe. In this work, we present stable isotope and clumped isotope data in order to constrain the conditions of fluid circulation and the relationship between fluid circulation and nickel ore-forming laterization focusing on the Koniambo Massif. For magnesite veins occurring at the base of the nappe, the high δ18O values between 27.8‰ and 29.5‰ attest to a low temperature formation. Clumped isotope analyses on magnesite give temperatures between 26 °C and 42 °C that are consistent with amorphous silica-magnesite oxygen isotope equilibrium. The meteoric origin of the fluid is indicated by calculated δ18Owater values between -3.4‰ to +1.5‰. Amorphous silica associated with magnesite or occurring in the coarse saprolite level displays a narrow range of δ18O values between 29.7‰ and 35.3‰. For quartz veins occurring at the top of the bedrock and at the saprolite level, commonly in association with Ni-talc-like minerals, the δ18O values are lower, between 21.8‰ and 29.0‰ and suggest low-temperature hydrothermal conditions (∼40-95 °C). Thermal equilibration of the fluid along the geothermic gradient before upward flow through the nappe and/or influence of exothermic reactions of serpentinization could be the source(s) of heat needed to form quartz veins under such conditions.

  20. Paired stable isotopes (O, C) and clumped isotope thermometry of magnesite and silica veins in the New Caledonia Peridotite Nappe

    NASA Astrophysics Data System (ADS)

    Quesnel, Benoît; Boulvais, Philippe; Gautier, Pierre; Cathelineau, Michel; John, Cédric M.; Dierick, Malorie; Agrinier, Pierre; Drouillet, Maxime

    2016-06-01

    The stable isotope compositions of veins provide information on the conditions of fluid-rock interaction and on the origin of fluids and temperatures. In New Caledonia, magnesite and silica veins occur throughout the Peridotite Nappe. In this work, we present stable isotope and clumped isotope data in order to constrain the conditions of fluid circulation and the relationship between fluid circulation and nickel ore-forming laterization focusing on the Koniambo Massif. For magnesite veins occurring at the base of the nappe, the high δ18O values between 27.8‰ and 29.5‰ attest to a low temperature formation. Clumped isotope analyses on magnesite give temperatures between 26 °C and 42 °C that are consistent with amorphous silica-magnesite oxygen isotope equilibrium. The meteoric origin of the fluid is indicated by calculated δ18Owater values between -3.4‰ to +1.5‰. Amorphous silica associated with magnesite or occurring in the coarse saprolite level displays a narrow range of δ18O values between 29.7‰ and 35.3‰. For quartz veins occurring at the top of the bedrock and at the saprolite level, commonly in association with Ni-talc-like minerals, the δ18O values are lower, between 21.8‰ and 29.0‰ and suggest low-temperature hydrothermal conditions (∼40-95 °C). Thermal equilibration of the fluid along the geothermic gradient before upward flow through the nappe and/or influence of exothermic reactions of serpentinization could be the source(s) of heat needed to form quartz veins under such conditions.

  1. Coulomb Fault Mechanics at Work in the Proterozoic: Strike-Slip Faults and Regional-Scale Veining in the Mt. Isa Inlier, Australia

    NASA Astrophysics Data System (ADS)

    Begbie, M. J.; Sibson, R. H.; Ghisetti, F. C.

    2005-12-01

    microbreccias and cataclasites containing vein fragments; (2) innumerable subvertical quartz veins (cm to m thick) lying subparallel to the bounding shear zones with textures ranging from pure dilation to multiply recemented breccias of wallrock and quartz fragments; (3) irregular non-systematic veins; and (4) occasional minor faults from the complementary set. Mutual cross-cutting relationships between all the structural components indicate penecontemporaneous development within the inferred stress field. Slickenfibers and striations along fault components indicate predominantly strike slip motion on subvertical planes. Homogenisation temperatures from quartz hosted fluid inclusions cluster at ~210°C while vein textures record histories of incremental hydrothermal deposition under low effective stress, probably in the epizonal environment (<1-2 km depth). This regional study demonstrates the existence of a rather uniform stress province, corresponding to an Andersonian regime and initiation of faults in accord with the coulomb failure criterion.

  2. Varicose vein - noninvasive treatment

    MedlinePlus

    Sclerotherapy; Laser therapy - varicose veins; Radiofrequency vein ablation; Endovenous thermal ablation; Ambulatory phlebectomy; Transilluminated power phlebotomy; Endovenous laser ablation; Varicose vein ...

  3. The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au-Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

    NASA Astrophysics Data System (ADS)

    Vidal, Conrado Permuy; Guido, Diego M.; Jovic, Sebastián M.; Bodnar, Robert J.; Moncada, Daniel; Melgarejo, Joan Carles; Hames, Willis

    2016-08-01

    The Cerro Negro district, within the Argentinian Deseado Massif province, has become one of the most significant recent epithermal discoveries, with estimated reserves plus resources of ˜6.7 Moz Au equivalent. The Marianas-San Marcos vein system contains about 70 % of the Au-Ag resources in the district. Mineralization consists of Upper Jurassic (155 Ma) epithermal Au- and Ag-rich veins of low to intermediate sulfidation style, hosted in and genetically related to Jurassic intermediate composition volcanic rocks (159-156 Ma). Veins have a complex infill history, represented by ten stages with clear crosscutting relationships that can be summarized in four main episodes: a low volume, metal-rich initial episode (E1), an extended banded quartz episode with minor mineralization (E2), a barren waning stage episode (E3), and a silver-rich late tectonic-hydrothermal episode (E4). The first three episodes are interpreted to have formed at the same time and probably from fluids of similar composition: a 290-230 °C fluid dominated by meteoric and volcanic waters (-3‰ to -0‰ δ18Owater), with <3 % NaCl equivalent salinity and with a magmatic source of sulfur (-1 to -2 ‰ δ34Swater). Metal was mainly precipitated at the beginning of vein formation (episode 1) due to a combination of boiling at ˜600 to 800 m below the paleowater table, and associated mixing/cooling processes, as evidenced by sulfide-rich bands showing crustiform-colloform quartz, adularia, and chlorite-smectite banding. During episodes 2 and 3, metal contents progressively decrease during continuing boiling conditions, and veins were filled by quartz and calcite during waning stages of the hydrothermal system, and the influx of bicarbonate waters (-6 to -8.5 ‰ δ18Owater). Hydrothermal alteration is characterized by proximal illite, adularia, and silica zone with chlorite and minor epidote, intermediate interlayered illite-smectite and a distal chlorite halo. This assemblage is in agreement with

  4. The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au-Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

    NASA Astrophysics Data System (ADS)

    Vidal, Conrado Permuy; Guido, Diego M.; Jovic, Sebastián M.; Bodnar, Robert J.; Moncada, Daniel; Melgarejo, Joan Carles; Hames, Willis

    2016-01-01

    The Cerro Negro district, within the Argentinian Deseado Massif province, has become one of the most significant recent epithermal discoveries, with estimated reserves plus resources of ˜6.7 Moz Au equivalent. The Marianas-San Marcos vein system contains about 70 % of the Au-Ag resources in the district. Mineralization consists of Upper Jurassic (155 Ma) epithermal Au- and Ag-rich veins of low to intermediate sulfidation style, hosted in and genetically related to Jurassic intermediate composition volcanic rocks (159-156 Ma). Veins have a complex infill history, represented by ten stages with clear crosscutting relationships that can be summarized in four main episodes: a low volume, metal-rich initial episode (E1), an extended banded quartz episode with minor mineralization (E2), a barren waning stage episode (E3), and a silver-rich late tectonic-hydrothermal episode (E4). The first three episodes are interpreted to have formed at the same time and probably from fluids of similar composition: a 290-230 °C fluid dominated by meteoric and volcanic waters (-3‰ to -0‰ δ18Owater), with <3 % NaCl equivalent salinity and with a magmatic source of sulfur (-1 to -2 ‰ δ34Swater). Metal was mainly precipitated at the beginning of vein formation (episode 1) due to a combination of boiling at ˜600 to 800 m below the paleowater table, and associated mixing/cooling processes, as evidenced by sulfide-rich bands showing crustiform-colloform quartz, adularia, and chlorite-smectite banding. During episodes 2 and 3, metal contents progressively decrease during continuing boiling conditions, and veins were filled by quartz and calcite during waning stages of the hydrothermal system, and the influx of bicarbonate waters (-6 to -8.5 ‰ δ18Owater). Hydrothermal alteration is characterized by proximal illite, adularia, and silica zone with chlorite and minor epidote, intermediate interlayered illite-smectite and a distal chlorite halo. This assemblage is in agreement with

  5. Characterization and modeling of illite crystal particles and growth mechanisms in a zoned hydrothermal deposit, Lake City, Colorado

    USGS Publications Warehouse

    Bove, D.J.; Eberl, D.D.; McCarty, D.K.; Meeker, G.P.

    2002-01-01

    Mean thickness measurements and crystal-thickness distributions (CTDs) of illite particles vary systematically with changes in hydrothermal alteration type, fracture density, and attendant mineralization in a large acid-sulfate/Mo-porphyry hydrothermal system at Red Mountain, near Lake City, Colorado. The hydrothermal illites characterize an extensive zone of quartz-sericite-pyrite alteration beneath two deeply rooted bodies of magmatic-related, quartz-alunite altered rock. Nineteen illites from a 3000 ft vertical drill hole were analyzed by XRD using the PVP-10 intercalation method and the computer program MudMaster (Bertaut-Warren-Averbach technique). Mean crystallite thicknesses, as determined from 001 reflections, range from 5-7 nanometers (nm) at depths from 0-1700 ft, then sharply increase to 10-16 nm at depths between 1800-2100 ft, and decrease again to 4-5 nm below this level. The interval of largest particle thickness correlates strongly with the zone of most intense quartz-sericite-pyrite alteration (QSP) and attendant high-density stockwork fracturing, and with the highest concentrations of Mo within the drill core. CTD shapes for the illite particles fall into two main categories: asymptotic and lognormal. The shapes of the CTDs are dependent on conditions of illite formation. The asymptotic CTDs correspond to a nucleation and growth mechanism, whereas surface-controlled growth was the dominant mechanism for the lognormal CTDs. Lognormal CTDs coincide with major through-going fractures or stockwork zones, whereas asymptotic CTDs are present in wallrock distal to these intense fracture zones. The increase in illite particle size and the associated zone of intense QSP alteration and stockwork veining was related by proximity to the dacitic magma(s), which supplied both reactants and heat to the hydrothermal system. However, no changes in illite polytype, which in other studies reflect temperature transitions, were observed within this interval.

  6. Varicose vein stripping

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002952.htm Varicose vein stripping To use the sharing features on this ... enable JavaScript. Vein stripping is surgery to remove varicose veins in the legs. Description Varicose veins are swollen, ...

  7. Varicose vein - noninvasive treatment

    MedlinePlus

    Sclerotherapy; Laser therapy - varicose veins; Radiofrequency vein ablation; Endovenous thermal ablation; Ambulatory phlebectomy; Transilluminated power phlebotomy; Endovenous laser ablation; Varicose ...

  8. Hydrothermal Processing

    SciTech Connect

    Elliott, Douglas C.

    2011-03-11

    This chapter is a contribution to a book on Thermochemical Conversion of Biomass being edited by Prof. Robert Brown of Iowa State University. It describes both hydrothermal liquefaction and hydrothermal gasification of biomass to fuels.

  9. Fluid inclusion petrography and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414

    NASA Astrophysics Data System (ADS)

    Brandstätter, J.; Kurz, W.; Krenn, K.; Micheuz, P.

    2015-12-01

    We present new data from microthermometric analyses of fluid inclusions entrapped in hydrothermal veins within lithified sediments and Cocos Ridge (CCR) basalt from IODP Expedition 344 site U1414 (Costa Rica) and concern on a primary task of Expedition 344, i.e. to evaluate fluid/rock interaction, the hydrologic system, and the geochemical processes (indicated by composition and volume of fluids) active within the incoming Cocos Plate. Mineralization of the veins and crosscutting relationships gives constraints for the different generation of veins. Calcium carbonate, commonly aragonite in the upper part and calcite in the lower part of the igneous basement, is usually present in veins as a late phase following the quartz precipitation and the clay minerals formation. The sequence of vein generations in the lithified sediments close to the contact within the CCR basalt is characterized by smaller veins filled by quartz, followed by massive intersecting calcite veins. A high fluid pressure can be concluded, due to wall rock fragments embedded within the filling and fractured mineral grains in the ground mass, which are close to the veins. This requires that the magmatic basement and the lithified sediments were covered by sequences of low permeability sediments forming a barrier that enabled build up elevated fluid pressure. The investigation of fluid inclusions in the lowest units of borehole 344-U1414, give clues about the source of the fluids and about the vein evolution within the incoming Cocos Plate close to Middle American Trench. The microthermometric analyses of the primary, almost aqueous, inclusions indicate a temperature range during entrapment between 200 and 420°C. The data indicate that seawater within the Cocos Ridge aquifer communicated with high-temperature fluids and/or were modified by heat advection. We consider the Galapagos hotspot and/ or the Cocos-Nazca spreading center as heat source. Fluids originated from mobilized sediment pore water

  10. Complex fragmentation and silicification structures in fault zones: quartz mineralization and repeated fragmentation along the Fountain Range Fault (Mt. Isa Inlier, Australia)

    NASA Astrophysics Data System (ADS)

    Seybold, Lina; Blenkinsop, Tom; Heuss, Soraya; Ord, Alison; Kruhl, Jörn H.

    2015-04-01

    In large-scale fault zones fracture networks are commonly generated by high volumes of pressurized fluids, followed by quartz precipitation. In this way large amounts of quartz are formed as microcrystalline masses and as complex vein systems, with partly highly different textures, as a result of different formation processes. Based on field and microstructural data and the quantification of vein patterns, the spatial and temporal connection between fragmentation, quartz crystallization and fluid and material flow along the Fountain Range Fault at Fountain Springs was investigated. Dextral strike-slip led to up to 25 km horizontal displacement along the fault. Due to various fragmentation and quartz formation processes, a ca. 100 m high, 80 - 100 m wide and km-long quartz ridge with numerous vein systems and variable microfabrics was formed. Locally, lenses of highly altered metamorphic wall-rocks occur in the quartz zone. Where exposed, the contact to wall rocks is sharp. Millimetre- to decimetre-thick quartz veins penetrate the wall-rocks only within metre distance from the contact. Several clearly distinguishable fine-grained reddish, brownish to dark and pigment-rich quartz masses form up to 50 m wide and up to several 100 m long steep lenses that build the major part of the silicified fault zone. A chronology can be established. Some of these lenses are oriented slightly oblique to the general trend of the quartz zone, in agreement with the supposed dextral strike slip along the fault. Numerous generations of typically µm-cm thick quartz veins transect the microcrystalline quartz masses and, locally, form anisotropic networks. In the quartz masses, angular fragments often composed of quartz with, again, internal fragmentation structures, indicate earlier fracturing and silicification events. Within the veins, quartz forms geodes, locally filled with fine-grained reddish quartz and palisade structures with feathery textures and fluid-inclusion zoning

  11. Deep Vein Thrombosis

    MedlinePlus

    MENU Return to Web version Deep Vein Thrombosis Overview What is deep vein thrombosis? Deep vein thrombosis (also called DVT) is a blood clot in a vein deep inside your body. These clots usually occur in your leg veins. While DVT is a fairly common condition, it is ...

  12. Deep Vein Thrombosis

    MedlinePlus

    Deep vein thrombosis, or DVT, is a blood clot that forms in a vein deep in the body. Most deep vein clots occur in the ... vein swells, the condition is called thrombophlebitis. A deep vein thrombosis can break loose and cause a serious problem ...

  13. Deep Vein Thrombosis

    MedlinePlus

    Deep vein thrombosis, or DVT, is a blood clot that forms in a vein deep in the body. Most deep vein clots occur in the lower leg or ... vein swells, the condition is called thrombophlebitis. A deep vein thrombosis can break loose and cause a ...

  14. The anatomy of a hydrothermal (explosion ) breccia, Abbot Village, central Maine

    SciTech Connect

    Roy, D.C. . Dept. of Geology and Geophysics)

    1993-03-01

    An apparently intrusive hydrothermal breccia is exposed in a large outcrop along Kingsbury Stream downstream from the Route 6 bridge in Abbot Village. The breccia intrudes the Siluro-Devonian Madrid Formation which is comprised of thick-bedded metasandstone interbedded with less fine-grained schist and phyllite at regional biotite grade. In the vicinity of the breccia, the bedding attitude in the Madrid is N60E 70SE and the section faces SE. The breccia is a concordant body with respect to bedding and the exposure shows what appears to the SW terminus of the intrusion which extends an unknown distance NE. The main phase of the breccia consists of randomly oriented and angular clasts'' of Madrid metasandstone and schist that are cemented by a quartz-dominated matrix. The random orientation of the clasts is present this phase were it is in contact with the country rock. The matrix comprises about 15% of the volume of the breccia and, in addition to quartz, contains biotite, galena, chalcopyrite ( ), pyrite, and an iron-carbonate. In some interstitial matrix, apparently late iron-carbonate fills post-quartz vugs that contain quartz-crystal terminations. The wall phase contains a higher proportion of biotite schist clasts that in places are bent around each other and metasandstone clasts. Quartz veins extending into the country rock near the breccia follow prominent regional joint directions and suggest hydrofracturing of the Madrid was the principal mechanism for breccia formation. The breccia is interpreted to be of explosive origin with the main phase of the body representing clasts that fell down within the vent'' following upward transport. The wall phase is taken to have formed due to adhesion to the wall of breccia clasts during the eruptive stage.

  15. Lineation-parallel c-axis Fabric of Quartz Formed Under Water-rich Conditions

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Zhang, J.; Li, P.

    2014-12-01

    The crystallographic preferred orientation (CPO) of quartz is of great significance because it records much valuable information pertinent to the deformation of quartz-rich rocks in the continental crust. The lineation-parallel c-axis CPO (i.e., c-axis forming a maximum parallel to the lineation) in naturally deformed quartz is generally considered to form under high temperature (> ~550 ºC) conditions. However, most laboratory deformation experiments on quartzite failed to produce such a CPO at high temperatures up to 1200 ºC. Here we reported a new occurrence of the lineation-parallel c-axis CPO of quartz from kyanite-quartz veins in eclogite. Optical microstructural observations, fourier transform infrared (FTIR) and electron backscattered diffraction (EBSD) techniques were integrated to illuminate the nature of quartz CPOs. Quartz exhibits mostly straight to slightly curved grain boundaries, modest intracrystalline plasticity, and significant shape preferred orientation (SPO) and CPOs, indicating dislocation creep dominated the deformation of quartz. Kyanite grains in the veins are mostly strain-free, suggestive of their higher strength than quartz. The pronounced SPO and CPOs in kyanite were interpreted to originate from anisotropic crystal growth and/or mechanical rotation during vein-parallel shearing. FTIR results show quartz contains a trivial amount of structurally bound water (several tens of H/106 Si), while kyanite has a water content of 384-729 H/106 Si; however, petrographic observations suggest quartz from the veins were practically deformed under water-rich conditions. We argue that the observed lineation-parallel c-axis fabric in quartz was inherited from preexisting CPOs as a result of anisotropic grain growth under stress facilitated by water, but rather than due to a dominant c-slip. The preservation of the quartz CPOs probably benefited from the preexisting quartz CPOs which renders most quartz grains unsuitably oriented for an easy a-slip at

  16. Tectonic record, magmatic history and hydrothermal alteration in the Hercynian Guérande leucogranite, Armorican Massif, France

    NASA Astrophysics Data System (ADS)

    Ballouard, C.; Boulvais, P.; Poujol, M.; Gapais, D.; Yamato, P.; Tartèse, R.; Cuney, M.

    2015-04-01

    The Guérande peraluminous leucogranite was emplaced at the end of the Carboniferous in the southern part of the Armorican Massif. At the scale of the intrusion, this granite displays structural heterogeneities with a weak deformation in the southwestern part, whereas the northwestern part is marked by the occurrence of S/C and mylonitic extensional fabrics. Quartz veins and pegmatite dykes orientations as well as lineations directions in the granite and its country rocks demonstrate both E-W and N-S stretching. Therefore, during its emplacement in an extensional tectonic regime, the syntectonic Guérande granite has probably experienced some partitioning of the deformation. The southwestern part is characterized by a muscovite-biotite assemblage, the presence of restites and migmatitic enclaves, and a low abundance of quartz veins compared to pegmatite dykes. In contrast, the northwestern part is characterized by a muscovite-tourmaline assemblage, evidence of albitization and gresenization and a larger amount of quartz veins. The southwestern part is thus interpreted as the feeding zone of the intrusion whereas the northwestern part corresponds to its apical zone. The granite samples display continuous compositional evolutions in the range of 69.8-75.3 wt.% SiO2. High initial 87Sr/86Sr ratios and low εNd(T) values suggest that the peraluminous Guérande granite (A/CNK > 1.1) was formed by partial melting of metasedimentary formations. Magmatic evolution was controlled primarily by fractional crystallization of K-feldspar, biotite and plagioclase (An20). The samples from the apical zone show evidence of secondary muscovitization. They are also characterized by a high content in incompatible elements such as Cs and Sn, as well as low Nb/Ta and K/Rb ratios. The apical zone of the Guérande granite underwent a pervasive hydrothermal alteration during or soon after its emplacement. U-Th-Pb dating on zircon and monazite revealed that the Guérande granite was emplaced

  17. Hydrothermal Growth of Polyscale Crystals

    NASA Astrophysics Data System (ADS)

    Byrappa, Kullaiah

    In this chapter, the importance of the hydrothermal technique for growth of polyscale crystals is discussed with reference to its efficiency in synthesizing high-quality crystals of various sizes for modern technological applications. The historical development of the hydrothermal technique is briefly discussed, to show its evolution over time. Also some of the important types of apparatus used in routine hydrothermal research, including the continuous production of nanosize crystals, are discussed. The latest trends in the hydrothermal growth of crystals, such as thermodynamic modeling and understanding of the solution chemistry, are elucidated with appropriate examples. The growth of some selected bulk, fine, and nanosized crystals of current technological significance, such as quartz, aluminum and gallium berlinites, calcite, gemstones, rare-earth vanadates, electroceramic titanates, and carbon polymorphs, is discussed in detail. Future trends in the hydrothermal technique, required to meet the challenges of fast-growing demand for materials in various technological fields, are described. At the end of this chapter, an Appendix 18.A containing a more or less complete list of the characteristic families of crystals synthesized by the hydrothermal technique is given with the solvent and pressure-temperature (PT) conditions used in their synthesis.

  18. QUARTZ FIBER ELECTROSCOPES

    DOEpatents

    Henderson, R.P.

    1957-09-17

    An instrument carried unobtrusively about the person such as in a finger ring to indicate when that person has been exposed to an unusual radiation hazard is described. A metallized quartz fiber is electrically charged to indicate a full scale reading on an etched glass background. The quartz fiber and the scale may be viewed through a magnifying lens for ease of reading. Incident radiation will ionize gaseous particles in the sealed structure thereby allowing the charge to leak off the quartz fiber with its resulting movement across the scale proportionally indicating the radiation exposure.

  19. Hydrothermal processes above the Yellowstone magma chamber: Large hydrothermal systems and large hydrothermal explosions

    USGS Publications Warehouse

    Morgan, L.A.; Shanks, W.C. Pat, III; Pierce, K.L.

    2009-01-01

    and vein-fi lling; and (5) areal dimensions of many large hydrothermal explosion craters in Yellowstone are similar to those of its active geyser basins and thermal areas. For Yellowstone, our knowledge of hydrothermal craters and ejecta is generally limited to after the Yellowstone Plateau emerged from beneath a late Pleistocene icecap that was roughly a kilometer thick. Large hydrothermal explosions may have occurred earlier as indicated by multiple episodes of cementation and brecciation commonly observed in hydrothermal ejecta clasts. Critical components for large, explosive hydrothermal systems include a watersaturated system at or near boiling temperatures and an interconnected system of well-developed joints and fractures along which hydrothermal fluids flow. Active deformation of the Yellowstone caldera, active faulting and moderate local seismicity, high heat flow, rapid changes in climate, and regional stresses are factors that have strong infl uences on the type of hydrothermal system developed. Ascending hydrothermal fluids flow along fractures that have developed in response to active caldera deformation and along edges of low-permeability rhyolitic lava flows. Alteration of the area affected, self-sealing leading to development of a caprock for the hydrothermal system, and dissolution of silica-rich rocks are additional factors that may constrain the distribution and development of hydrothermal fields. A partial lowpermeability layer that acts as a cap to the hydrothermal system may produce some over-pressurization, thought to be small in most systems. Any abrupt drop in pressure initiates steam fl ashing and is rapidly transmitted through interconnected fractures that result in a series of multiple large-scale explosions contributing to the excavation of a larger explosion crater. Similarities between the size and dimensions of large hydrothermal explosion craters and thermal fields in Yellowstone may indicate that catastrophic events which result in l

  20. The solubility of gallium oxide in vapor and two-phase fluid filtration in hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Bychkov, Andrew; Matveeva, Svetlana; Nekrasov, Stanislav

    2010-05-01

    The solubility of gallium and aluminum oxides in gas phase in the system Ga2O3 (Al2O3)-HCl-H2O was studied at 150-350°C and pressure up to saturated vapor. The concentration of gallium increases with the increasing of HCl pressure. The formulae of gallium gaseous specie was determined as GaOHCl2. The constant of gallium oxide solubility reaction was calculated at 150, 200, 250, 300 and 350°C. The concentration of aluminum in gas phase is insignificant in the same conditions. The possibility of gallium transportation in gas phase with small quantity of Al allow to divide this elements in hydrothermal processes with gas phase. The Ga/Al ratio in muscovite can be used as the indicator of gas phase separation and condensation. This indicator was not considered in the geochemical literature earlier. The separation of gas and liquid phases was determined in Akchatau (Kazahstan) and Spokoinoe (Russia) greisen W deposit by carbon isotope fractionation of carbon dioxide in fluid inclusion. The important feature of both ore mains is heterogenization and boiling of ore-forming fluids. Greisen ore bodies are formed as a result of strongly focused solution flow in the T-P gradient fields. It is possible to divide ore bodies of Akchatau in two types: muscovite and quartz. Muscovite type veins are thin and have small metasyntactic zone. Quartz type veins are localized in fault with large vertical extent (500 m) and content the large quantity of wolframite. These veins formed in condition of significant pressure decreasing from 2.5 to 0.5 kbar with fluid boiling. Gas and liquid phase separation specifies the vertical zonality of quartz type veins. The gas phase with the high gallium concentration is separated from a flow of liquid phase. Liquid phase react with the granites forming greisen metasomatites. Condensation of the gas phase in upper parts of massive produces the increasing of Ga/Al ratio in muscovite 3-5 times more, then in granites and bottom part of vein (from 2×10

  1. Phyllosilicate minerals in the hydrothermal mafic-ultramafic-hosted massive-sulfide deposit of Ivanovka (southern Urals): comparison with modern ocean seafloor analogues

    NASA Astrophysics Data System (ADS)

    Nimis, Paolo; Tesalina, Svetlana G.; Omenetto, Paolo; Tartarotti, Paola; Lerouge, Catherine

    We have studied textural relationships and compositions of phyllosilicate minerals in the mafic-ultramafic-hosted massive-sulfide deposit of Ivanovka (Main Uralian Fault Zone, southern Urals). The main hydrothermal phyllosilicate minerals are Mg-rich chlorite, variably ferroan talc, (Mg, Si)-rich and (Ca, Na, K)-poor saponite (stevensite), and serpentine. These minerals occur both as alteration products after mafic volcanics and ultramafic protoliths and, except serpentine, as hydrothermal vein and seafloor mound-like precipitates associated with variable amounts of (Ca, Mg, Fe)-carbonates, quartz and Fe and Cu (Co, Ni) sulfides. Brecciated mafic lithologies underwent pervasive chloritization, while interlayered gabbro sills underwent partial alteration to chlorite + illite +/- actinolite +/- saponite +/- talc-bearing assemblages and later localized deeper alteration to chlorite +/- saponite. Ultramafic and mixed ultramafic-mafic breccias were altered to talc-rich rocks with variable amounts of chlorite, carbonate and quartz. Chloritization, locally accompanied by formation of disseminated sulfides, required a high contribution of Mg-rich seawater to the hydrothermal fluid, which could be achieved in a highly permeable, breccia-dominated seafloor. More evolved hydrothermal fluids produced addition of silica, carbonates and further sulfides, and led to local development of saponite after chlorite and widespread replacement of serpentine by talc. The Ivanovka deposit shows many similarities with active and fossil hydrothermal sites on some modern oceanic spreading centers characterized by highly permeable upflow zones. However, given the arc signature of the ore host rocks, the most probable setting for the observed alteration-mineralization patterns is in an early-arc or forearc seafloor-subseafloor environment, characterized by the presence of abundant mafic-ultramafic breccias of tectonic and/or sedimentary origin.

  2. Vacuum electrolysis of quartz

    DOEpatents

    King, James Claude

    1976-01-13

    The disclosure is directed to a method for processing quartz used in fabricating crystal resonators such that transient frequency change of resonators exposed to pulse irradiation is virtually eliminated. The method involves heating the crystal quartz in a hydrogen-free atmosphere while simultaneously applying an electric field in the Z-axis direction of the crystal. The electric field is maintained during the cool-down phase of the process.

  3. Towards a quantitative description of fracture sealing: Phase-field modeling of mineral precipitation in veins

    NASA Astrophysics Data System (ADS)

    Wendler, F.; Blum, P.; Thaler, H.; Nestler, B.; Okamoto, A.

    2013-12-01

    Alongside with calcite the growth of quartz establishes the most important mineralization processes in fractures and determines the fluid-rock interaction in the earth's crust. Tectonically caused deformation, fracturing and fluid transport leaves clear detectable traces in the microstructure of the mineralized veins. The underlying physical processes such as diffusion, advection, heat transport and crystal growth have to be captured at the mesoscale (or pore/grain scale). Any analysis is complicated by the facts that these processes are highly nonlinear, and geological boundary conditions as well as many of the kinetic growth parameters are not precisely known. As the microstructures and compositional inhomogeneity of veins could be used to enravel the history of the rock deformation process and the fluid pathways through former fracture networks, spatio-temporal models of vein mineral growth are of special interest. Different from previous approaches to simulate vein growth, we adapt a thermodynamically consistent phase-field model (PFM) which combines irreversible thermodynamics of interfaces and bulk phases with a kinetic growth law and mass transport equations (Wendler et al. 2011). Here, we study the simplest case where preexisting grains of a fracture surface are the seeds for epitaxial overgrowth. Each grain in a 3D domain is captured by a phase field with individual orientation. The model evolves in discrete time steps using a finite difference algorithm on a regular grid, optimized for large grain assemblies. In the present study we provide a brief overview, how the PFM is configured using thermodynamic data from established models for growth and dissolution, kinetic information from in and ex situ microstructural observations and dihedral angles from equilibration experiments. In the case of quartz, previously conducted hydrothermal batch flow growth experiments were analysed to calibrate the model (Okamoto & Sekine 2011). Results from 3D simulations

  4. Fluid evolution in a volcanic-hosted epithermal carbonate-base metal-gold vein system: Alto de la Blenda, Farallón Negro, Argentina

    NASA Astrophysics Data System (ADS)

    Márquez-Zavalía, M. Florencia; Heinrich, Christoph A.

    2016-03-01

    Alto de la Blenda is a ˜6.6-Ma intermediate-sulphidation epithermal vein system in the Farallón Negro Volcanic Complex, which also hosts the 7.1-Ma porphyry-Cu-Au deposit of Bajo de la Alumbrera. The epithermal vein system is characterised by a large extent and continuity (2 km × 400 m open to depth × 6 m maximum width) and an average gold grade of ˜8 g/t. The vein is best developed within an intrusion of a fine-grained equigranular monzonite, interpreted as the central conduit of a stratovolcano whose extrusive activity ended prior to porphyry-Cu-Au emplacement at Bajo de la Alumbrera, which is in turn cut by minor epithermal veins. The Alto de la Blenda vein consists predominantly of variably Mn-rich carbonates and quartz, with a few percent of pyrite, sphalerite, galena and other sulphide and sulphosalt minerals. Four phases of vein opening, hydrothermal mineralisation and repeated brecciation can be correlated between different vein segments. Stages 2 and 3 contain the greatest fraction of sulphide and gold. They are separated by the emplacement of a polymictic breccia containing clasts of quartz feldspar porphyry as well as basement rocks. Fluid inclusions in quartz related to stages 2 to 4 are liquid rich with 2-4 wt% NaCl(eq). They homogenise between 160 and 300 °C, with very consistent values within each assemblage. Vapour inclusions are practically absent in the epithermal vein. Quartz fragments in the polymictic breccia contain inclusions of intermediate to vapour-like density and similar low salinity (˜3 wt% NaCl(eq)), besides rare brine inclusions containing halite. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of epithermal inclusions indicate high concentrations of K, Fe, As, Sb, Cs, and Pb that significantly vary within and through subsequent vein stages. Careful consideration of detection limits for individual inclusions shows high gold concentrations of ˜0.5 to 3 ppm dissolved in the ore fluid, which

  5. Hydrogen Isotope Evidence for Giant Meteoric-Hydrothermal Systems Associated with Extension and Magmatism in the Southern Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Holk, G. J.; McCarthy, A.

    2014-12-01

    Over 400 published mineral and fluid inclusion δD values from the southern Canadian Cordillera and our new data from the Eocene Penticton Group Volcanics and Coryell Intrusive Suite of the Southern Omineca Belt and the Western Metamorphic Belt of the Central Coast Orogen are compiled using GIS. δDH2O is estimated using published D/H fractionation factors at 400°C; the error is ±20‰, small enough to distinguish deep magmatic/metamorphic fluids from meteoric-hydrothermal fluids. Histogram plots of δDH2O values estimated from minerals reveal peaks at δD = -60‰ (deep fluid) and ­-110‰ (Early Cenozoic meteoric-hydrothermal fluid); this provides a clear distinction between the two kinds of fluid. Our analysis reveals that syn-extensional meteoric-hydrothermal systems (δDH2O < -80‰) affected the eastern margin of the Coast Ranges Batholith between latitude 49° and 55° and the Omineca Belt between latitude 49° and 52°45'; both regions were affected by detachment faulting during late stages of magmatism in the Early Cenozoic (e.g., Parrish et al., 1988; Crawford et al., 2009). Zones that escaped the effects of meteoric-hydrothermal systems, preserving the D/H signature of deep fluids (δD > -80‰), include the Western Metamorphic Belt, the Western and Central Coast Ranges Batholith, the belt of Jurassic metamorphism that extends from the Cariboo Mountains to the Purcell Mountains, and the deepest structural levels of the Shuswap Metamorphic Core Complex; most of these samples have quartz-feldspar 18O/16O fractionations indicative of magmatic temperatures. High δDH2O values (> -50‰) suggest seawater alteration of the plutons of Vancouver Island (Magaritz and Taylor, 1986). Histogram plots of vein quartz fluid inclusion δD values (Nesbitt and Muehlenbachs, 1995) reveal three peaks that include the two produced by the mineral δD values, but these data are dominated by a large peak at δD = -150, a value similar to modern meteoric waters in the region

  6. Composite synvolcanic intrusions associated with Precambrian VMS-related hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Galley, Alan G.

    2003-06-01

    Large subvolcanic intrusions are recognized within most Precambrian VMS camps. Of these, 80% are quartz diorite-tonalite-trondhjemite composite intrusions. The VMS camps spatially associated with composite intrusions account for >90% of the aggregate sulfide tonnage of all the Precambrian, intrusion-related VMS camps. These low-alumina, low-K, and high-Na composite intrusions contain early phases of quartz diorite and tonalite, followed by more voluminous trondhjemite. They have a high proportion of high silica (>74% SiO2) trondhjemite which is compositionally similar to the VMS-hosting rhyolites within the volcanic host-rock successions. The quartz-diorite and possibly tonalite phases follow tholeiitic fractionation trends whereas the trondhjemites fall within the composition field for primitive crustal melts. These transitional M-I-type primitive intrusive suites are associated with extensional regimes within oceanic-arc environments. Subvolcanic composite intrusions related to the Archean Sturgeon Lake and Noranda, and Paleoproterozoic Snow Lake VMS camps range in volume from 300 to 1,000 km3. Three have a sill morphology with strike lengths between 15 and 22 km and an average thickness between 1,500 and 2,000 m. The fourth has a gross stock-like shape. The VMS deposits are principally restricted to the volcanic strata above the strike length of the intrusions, as are areally extensive, thin exhalite units. The composite intrusions contain numerous internal phases which are commonly clustered within certain parts of the composite intrusion. These clusters underlie eruptive centers surrounded by areas of hydrothermal alteration and which contain most of the VMS deposits. Early quartz-diorite and tonalite phases appear to have intruded in rapid succession. Evidence includes gradational contacts, magma mixing and disequilibrium textures. They appear to have been emplaced as sill-dike swarms. These early phases are present as pendants and xenoliths within later

  7. Initiation and collapse of active circulation in a hydrothermal system at the Mid-Atlantic Ridge, 23°N

    NASA Astrophysics Data System (ADS)

    Gallinatti, Barbara Cosens

    1984-05-01

    Gabbro and basalt, collected from an area south of the Kane Fracture Zone along the Mid-Atlantic Ridge, have three stages of alteration which record the cooling of a hydrothermal system: (1) Stage 1. Penetration of seawater began between 400° and 550°C, altering pyroxene to fibrous green amphibole. (2) Stage 2. Propylitic alteration formed along connected fractures between 250° and 300°C. As fracture density increased, the Fe/Mg ratio of chlorite increased, the final result being an Fe chlorite-quartz-sulfide breccia. (3) Stage 3. Late smectite veinlets formed at low temperatures (≤200°C) after active circulation ceased The study focuses on stage 2 alteration. By assuming local equilibrium between alteration minerals and the hydrothermal fluid, constraints can be placed on the fluid composition responsible for stage 2 alteration, the stage associated with deposition of sulfides. The following activities of species in solution were determined for the system FeO Na2O-CaO-MgO-Al2O3-SiO2-H2O at 350 bars and 250°C: log a (Ca++)/a2 (H+) = 8.0, log a (Na+)/a (H+) = 5.0, log a (Fe++)/a2 (H+) = 1.7, log a (Mg++)/a2 (H+) = 6.0. Log a (SiO2) was set at quartz saturation (-2.3 at 350 bars and 250°C). Fluid inclusions record the introduction of a low temperature, seawater-salinity fluid during formation of the latest quartz veins associated with stage 2 alteration. Mixing of this and the hydrothermal fluid caused a drop in temperature and increase in oxidation state, resulting in increased precipitation of quartz, pyrite and chalcopyrite. The salinities of fluid inclusions trapped in quartz during stage 2 alteration are as much as 3 times that of seawater. Concentration of a fluid initially of seawater salinity may be the result of boiling at ≥350°C and ≤3000 m depth.

  8. Silica Transport, Deposition and Porosity Evolution in a Fracture : Insights from Hydrothermal Flow-through Experiments

    NASA Astrophysics Data System (ADS)

    Okamoto, A.; Yamada, R.; Saishu, H.; Tsuchiya, N.

    2014-12-01

    Geofluids contain a large amount of silica, which solubility changes depending on temperature and pressure. Ubiquitous occurrences of various silica deposits (quartz veins, silica sinter, scales) suggest that silica precipitation plays an important role on temporal and spatial variation of hydrological properties of the Earth's crusts. A pressure drop, for example, induced by seismicity, is one of the driving forces for silica precipitation within the crusts. In spite of the importance of silica depositions in fractures, how porosity and permeability evolution during silica precipitation is still poorly understood. In this study, we conducted the hydrothermal experiments for silica precipitation from supersaturated solutions in vapor (370˚C, 20 MPa) and supercritical (420 ˚C, 30 MPa) conditions with flow rate of 1 g/min. After the experiments, we analyzed the 3-D porosity structures by X-ray CT, and then by making thin section. We developed a tube-in-tube vessel, which is composed of main vessel (made of SUS316), and inner alumina tube (6 mm inner diameter), to make a horizontal flow path. We did not used rock/mineral substrates, and alumina balls (1 mm diameter) are closely packed in the inner tube. In both situations, a significant amount of silica deposited within a week, showing contrasting porosity structures between vapor and supercritical conditions. In vapor conditions, the precipitates are fine-grained quartz aggregate, and the most deposited at around 38 mm from the inlet. The pores were filled from the bottom to the top in the tube. In contrast, in the supercritical conditions, the precipitates are composites of amorphous silica and quartz; which accumulated around the alumina balls uniformly. Quartz grains are formed in amorphous silica layers, and the most porosity reduction occurred at around 25 mm from the inlet. A simple model of cellular automaton involving particle flow, adsorption, settling and deposition reveals that the relative magnitude of

  9. Vein morphology, host rock deformation and the origin of the fabrics of echelon mineral veins

    NASA Astrophysics Data System (ADS)

    Nicholson, R.

    A system of sigmoidal echelon veins from a sample of sandstone from the Upper Carboniferous Culm sequence of southwest England is described. Veins are separated from one another by strips of sandstone, and divided internally by thin seams with crack—seal fabrics. The latter extend as thin veins into the sandstone host rock without change of fabric. Seams appear to be merely parts of crack—seal veins formed in a first phase of deposition in only minutely opened fractures. This phase ended as rates of fracture opening greatly increased. To allow for this widespread opening host rock between dilatating fractures (sandstone strips and seams) had to be deformed. This deformation was limited, however, to rotation, bending and fracture. Shear displacement was a function of dilatation, not zone-parallel ductile shear strain. The textures of the quartz and carbonate aggregates filling the sigmoidal veins show that second-phase crystallization took place into cavities opening more rapidly than growth was able to fill them. Growth for the greater part took place from fibres in seams and not off vein walls of the sandstone host rock. Coarsest aggregates fill the arcs of folds in seams, where rates of vein opening might be expected to have been highest and the scope for competitive cavity growth greatest.

  10. Hydrothermal alteration and mass exchange in the hornblende latite porphyry, Rico, Colorado

    NASA Astrophysics Data System (ADS)

    Larson, Peter B.; Cunningham, Charles G.; Naeser, Charles W.

    1994-03-01

    The Rico paleothermal anomaly, southwestern Colorado, records the effects of a large hydrothermal system that was active at 4 Ma. This hydrothermal system produced the deep Silver Creek stockwork Mo deposit, which formed above the anomaly's heat source, and shallower base and precious-metal vein and replacement deposits. A 65 Ma hornblende latite porphyry is present as widespread sills throughout the area and provided a homogenous material that recorded the effects of the hydrothermal system up to 8 km from the center. Hydrothermal alteration in the latite can be divided into a proximal facies which consists of two assemblages, quartz-illite-calcite and chlorite-epidote, and a distal facies which consists of a distinct propylitic assemblage. Temperatures were gradational vertically and laterally in the anomaly, and decreased away from the centra heat source. A convective hydrothermal plume, 3 km wide and at least 2 km high, was present above the stock-work molybdenum deposit and consisted of upwelling, high-temperature fluids that produced the proximal alteration facies. Distal facies alteration was produced by shallower cooler fluids. The most important shallow base and precious-metal vein deposits in the Rico district are at or close to the boundary of the thermal plume. Latite within the plume had a large loss of Na2O, large addition of CaO, and variable SiO2 exchante. Distal propylitized latite samples lost small amounts of Na2O and CaO and exchanged minor variable amounts of SiO2. The edge of the plume is marked by steep Na2O exchange gradients. Na2O exchange throughout the paleothermal anomaly was controlled by the reaction of the albite components in primary plagioclase and alkali feldspars. Initial feldspar alteration in the distal facies was dominated by reaction of the plagioclase, and the initial molar ratio of reactants (alkali feldspar albite component to plagioclase albite component) was 0.35. This ratio of the moles of plagioclase to alkali feldspar

  11. Optical contacting of quartz

    NASA Technical Reports Server (NTRS)

    Payne, L. L.

    1982-01-01

    The strength of the bond between optically contacted quartz surfaces was investigated. The Gravity Probe-B (GP-B) experiment to test the theories of general relativity requires extremely precise measurements. The quartz components of the instruments to make these measurements must be held together in a very stable unit. Optical contacting is suggested as a possible method of joining these components. The fundamental forces involved in optical contacting are reviewed and relates calculations of these forces to the results obtained in experiments.

  12. Quartz ball valve

    NASA Technical Reports Server (NTRS)

    Goetz, C.; Ingle, W. M. (Inventor)

    1980-01-01

    A ball valve particularly suited for use in the handling of highly corrosive fluids is described. It is characterized by a valve housing formed of communicating segments of quartz tubing, a pair of communicating sockets disposed in coaxial alignment with selected segments of tubing for establishing a pair of inlet ports communicating with a common outlet port, a ball formed of quartz material supported for displacement between the sockets and configured to be received alternately thereby, and a valve actuator including a rod attached to the ball for selectively displacing the ball relative to each of the sockets for controlling fluid flow through the inlet ports.

  13. Hydrothermal modification of host rock geochemistry within Mo-Cu porphyry deposits in the Galway Granite, western Ireland

    NASA Astrophysics Data System (ADS)

    Tolometti, Gavin; McCarthy, Will

    2016-04-01

    Hydrothermal alteration of host rock is a process inherent to the formation of porphyry deposits and the required geochemical modification of these rocks is regularly used to indicate proximity to an economic target. The study involves examining the changes in major, minor and trace elements to understand how the quartz vein structures have influenced the chemistry within the Murvey Granite that forms part of the 380-425Ma Galway Granite Complex in western Ireland. Molybdenite mineralisation within the Galway Granite Complex occurred in close association with protracted magmatism at 423Ma, 410Ma, 407Ma, 397Ma and 383Ma and this continues to be of interest to active exploration. The aim of the project is to characterize hydrothermal alteration associated with Mo-Cu mineralisation and identify geochemical indicators that can guide future exploration work. The Murvey Granite intrudes metagabbros and gneiss that form part of the Connemara Metamorphic complex. The intrusion is composed of albite-rich pink granite, garnetiferous granite and phenocrytic orthoclase granite. Minor doleritic dykes post-date the Murvey Granite, found commonly along its margins. Field mapping shows that the granite is truncated to the east by a regional NW-SE fault and that several small subparallel structures host Mo-Cu bearing quartz veins. Petrographic observations show heavily sericitized feldspars and plagioclase and biotite which have undergone kaolinization and chloritisation. Chalcopyrite minerals are fine grained, heavily fractured found crystallized along the margins of the feldspars and 2mm pyrite crystals. Molybdenite are also seen along the margins of the feldspars, crystallized whilst the Murvey Granite cooled. Field and petrographic observations indicate that mineralisation is structurally controlled by NW-SE faults from the selected mineralization zones and conjugate NE-SW cross cutting the Murvey Granite. Both fault orientations exhibit quartz and disseminated molybdenite

  14. Portal Vein Thrombosis

    PubMed Central

    Mallet, Thierry; Soltys, Remigiusz; Loarte, Pablo

    2015-01-01

    Portal vein thrombosis (PVT) is the blockage or narrowing of the portal vein by a thrombus. It is relatively rare and has been linked with the presence of an underlying liver disease or prothrombotic disorders. We present a case of a young male who presented with vague abdominal symptoms for approximately one week. Imaging revealed the presence of multiple nonocclusive thrombi involving the right portal vein, the splenic vein, and the left renal vein, as well as complete occlusion of the left portal vein and the superior mesenteric vein. We discuss pathogenesis, clinical presentation, and management of both acute and chronic thrombosis. The presence of PVT should be considered as a clue for prothrombotic disorders, liver disease, and other local and general factors that must be carefully investigated. It is hoped that this case report will help increase awareness of the complexity associated with portal vein thrombosis among the medical community. PMID:25802795

  15. Preventing Deep Vein Thrombosis

    MedlinePlus

    ... Patient Education FAQs Preventing Deep Vein Thrombosis Patient Education Pamphlets - Spanish Preventing Deep Vein Thrombosis FAQ174, August 2011 PDF ... Your Practice Patient Safety & Quality Payment Reform (MACRA) Education & Events Annual ... Pamphlets Teen Health About ACOG About Us Leadership & ...

  16. Galileo quartz clock

    NASA Technical Reports Server (NTRS)

    Block, M.; Meirs, M.; Rosenfeld, M.; Garriga, P. C.

    1979-01-01

    A quartz oscillator for use in the Galileo experiment (orbiter and Probe) for Jupiter mission 1982 are described. This oscillator has achieved significant performance breakthroughs by the use of an SC cut, double rotated, crystal in a titanium dewar flask. Some of the performance parameters as well as the design feature of the oscillator are presented.

  17. Geochemical behavior of rare earth elements of the hydrothermal alterations within the Tepeoba porphyry Cu-Mo-Au deposits at Balikesir, NW Turkey

    NASA Astrophysics Data System (ADS)

    Doner, Zeynep; Abdelnasser, Amr; Kiran Yildirim, Demet; Kumral, Mustafa

    2016-04-01

    This work reports the geochemical characteristics and behavior of the rare earth elements (REE) of the hydrothermal alteration of the Tepeoba porphyry Cu-Mo-Au deposit located in the Anatolian tectonic belt at Biga peninsula (Locally Balikesir province), NW Turkey. The Cu-Mo-Au mineralization at this deposit hosted in the hornfels rocks and related to the silicic to intermediate intrusion of Eybek pluton. It locally formed with brecciated zones and quartz vein stockworks, as well as the brittle fracture zones associated with intense hydrothermal alteration. Three main alteration zones with gradual boundaries formed in the mine area in the hornfels rock that represents the host rock, along that contact the Eybek pluton; potassic, propylitic and phyllic alteration zones. The potassic alteration zone that formed at the center having high amount of Cu-sulfide minerals contains biotite, muscovite, and sericite with less amount of K-feldspar and associated with tourmalinization alteration. The propylitic alteration surrounds the potassic alteration having high amount of Mo and Au and contains chlorite, albite, epidote, calcite and pyrite. The phyllic alteration zone also surrounds the potassic alteration containing quartz, sericite and pyrite minerals. Based on the REE characteristics and content and when we correlate the Alteration index (AI) with the light REEs and heavy REEs of each alteration zone, it concluded that the light REEs decrease and heavy REEs increase during the alteration processes. The relationships between K2O index with Eu/Eu* and Sr/Sr* reveals a positive correlation in the potassic and phyllic alteration zones and a negative correlation in the propylitic alteration zone. This refers to the hydrothermal solution which is responsible for the studied porphyry deposits and associated potassic and phyllic alterations has a positive Eu and Sr anomaly as well as these elements were added to the altered rock from the hydrothermal solution. Keywords: Rare

  18. Deep Vein Thrombosis

    MedlinePlus

    ... page from the NHLBI on Twitter. What Is Deep Vein Thrombosis? Español Deep vein thrombosis (throm-BO-sis), or DVT, is a blood clot that forms in a vein deep in the body. Blood clots occur when blood ...

  19. Varicose veins and venous insufficiency

    MedlinePlus

    Varicose veins are swollen, twisted, and enlarged veins that you can see under the skin. They are often ... from the blood that collects there, which causes varicose veins. Smaller varicose veins that you can see on ...

  20. Fluid inclusions in quartz crystals from South-West Africa.

    NASA Technical Reports Server (NTRS)

    Kvenvolden, K. A.; Roedder, E.

    1971-01-01

    Quartz crystals from calcite veins of unknown age in Precambrian metasedimentary rocks at Geiaus No. 6 and Aukam farms in South-West Africa contain both primary and secondary inclusions filled with one substance or a combination of substances. These substances include organic liquid, moderately saline aqueous liquid, dark-colored solid, and a vapor. Analysis of these materials by microscopy and by gas chromatography and mass spectrometry shows the presence of constituents of both low and high molecular weights.

  1. Orogenesis, high-T thermal events, and gold vein formation within metamorphic rocks of the Alaskan Cordillera

    USGS Publications Warehouse

    Goldfarb, R.J.; Snee, L.W.; Pickthorn, W.J.

    1993-01-01

    Mesothermal, gold-bearing quartz veins are widespread within allochthonous terranes of Alaska that are composed dominantly of greenschist-facies metasedimentary rocks. The most productive lode deposits are concentrated in south-central and southeastern Alaska; small and generally nonproductive gold-bearing veins occur upstream from major placer deposits in interior and northern Alaska. Ore-forming fluids in all areas are consistent with derivation from metamorphic devolatilisation reactions, and a close temporal relationship exists between high-T tectonic deformation, igneous activity, and gold mineralization. Ore fluids were of consistently low salinity, CO2-rich, and had ??18O values of 7 ???-12??? and ??D values between -15??? and -35???. Upper-crustal temperatures within the metamorphosed terranes reached at least 450-500??C before onset of significant gold-forming hydrothermal activity. In southern Alaska, gold deposits formed during latter stages of Tertiary, subduction-related, collisional orogenesis and were often temporally coeval with calc-alkaline magmatism. -from Authors

  2. Gamma ray spectrometry for recognition of hydrothermal alteration zones related to a low sulfidation epithermal gold mineralization (eastern Pontides, NE Türkiye)

    NASA Astrophysics Data System (ADS)

    Maden, Nafiz; Akaryalı, Enver

    2015-11-01

    This study presents an interpretation of radiospectrometric and magnetic data of Arzular mineralization site, which is one of the best examples for epithermal gold deposits located in the southern zone of the Eastern Pontides (NE Türkiye). Potassium is generally the most useful pathfinder element for gold mineralization zones because of its high level in altered rock surrounding the deposits. Where gold is hosted within quartz veins, typically the vein is low in the radioelements, but the hydrothermally altered host rocks will usually have a distinct radioelement signature useful for exploration. In this study, magnetic, susceptibility and radiospectrometric survey data radiometric signatures associated with the host rocks favorable for the mineralization, enhancing techniques such as the ratio maps as well as potassium (%K), equivalent thorium (eTh ppm) and equivalent uranium (eU ppm) maps were utilized. Our analysis showed that the gold mineralization associated with the alteration is significantly related to increase in potassium, due to adularia, a low T K-feldspar, and decreases in uranium and thorium due to the hydrothermal alteration and magmatic intrusion processes during the regional tectonic activities.

  3. Branch retinal vein occlusion.

    PubMed

    Hamid, Sadaf; Mirza, Sajid Ali; Shokh, Ishrat

    2008-01-01

    Retinal vein occlusions (RVO) are the second commonest sight threatening vascular disorder. Branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO) are the two basic types of vein occlusion. Branch retinal vein occlusion is three times more common than central retinal vein occlusion and- second only to diabetic retinopathy as the most common retinal vascular cause of visual loss. The origin of branch retinal vein occlusion undoubtedly includes both systemic factors such as hypertension and local anatomic factors such as arteriovenous crossings. Branch retinal vein occlusion causes a painless decrease in vision, resulting in misty or distorted vision. Current treatment options don't address the underlying aetiology of branch retinal vein occlusion. Instead they focus on treating sequelae of the occluded venous branch, such as macular oedema, vitreous haemorrhage and traction retinal detachment from neovascularization. Evidences suggest that the pathogenesis of various types of retinal vein occlusion, like many other ocular vascular occlusive disorders, is a multifactorial process and there is no single magic bullet that causes retinal vein occlusion. A comprehensive management of patients with retinal vascular occlusions is necessary to correct associated diseases or predisposing abnormalities that could lead to local recurrences or systemic event. Along with a review of the literature, a practical approach for the management of retinal vascular occlusions is required, which requires collaboration between the ophthalmologist and other physicians: general practitioner, cardiologist, internist etc. as appropriate according to each case. PMID:19385476

  4. Fluid inclusion and isotopic systematics of an evolving magmatic-hydrothermal system

    SciTech Connect

    Moore, J.N.; Gunderson, R.P.

    1995-10-01

    The Geysers, California, is the site of a long-lived hydrothermal system that initially developed 1.5-2 m.y. ago in response to the intrusion of a hypabyssal granitic pluton. Although wells drilled into The Geysers produce only dry steam, fluid inclusion, isotopic, and mineralogic data demonstrate that the present vapor-dominated regime evolved from an earlier and more extensive, liquid-dominated hydrothermal system. Circulation of these early fluids produced veins characterized by tourmaline {+-} biotite {+-} actinolite {+-} clinopyroxene within the pluton and adjacent biotite-rich hornfels, actinolite {+-} ferroaxinite {+-} epidote and epidote {+-} chlorite within the intermediate parts of the thermal system and calcite in the outer parts. Potassium feldspar and quartz are present in all assemblages. Pressure-corrected homogenization temperatures and apparent salinities of fluid inclusions trapped in vein minerals range from 440{degrees}C and 44 wt% NaCl equivalent within the hornfels (<600 m from the pluton) to 325{degrees}C and 5 wt% NaCl equivalent at distances of approximately 1500 m from the intrusion. We suggest that the shallow, moderate salinity fluids are connate waters modified by water-rock interactions while the high-salinity fluids are interpreted as magmatic brines. Halite-dissolution temperatures of inclusions in the hornfels and pluton indicate that the magnetic fluids were trapped at lithostatic pressures (300-900 bars). In contrast, homogenization temperatures of the connate fluids suggest trapping under hydrostatic pressures of less than several hundred bars. Whole-rock {delta}{sup 18}O values of samples from The Geysers display systematic variations with respect to depth, location within the field, and grade of alteration. At depths below +610 m relative to mean sea level, the {delta}{sup 18}O values are strongly zoned around a northwest-southeast trending low located near the center of the steam reservoir. 77 refs., 15 figs., 2 tabs.

  5. Quartz Rheology - A Multidisciplinary Analysis of a Fossil Brittle-ductile Shear Array in the Central Southern Alps, New Zealand

    NASA Astrophysics Data System (ADS)

    Grigull, S.; Little, T. A.; Ellis, S.

    2006-12-01

    An exhumed fossil brittle-ductile shear array in the central Southern Alps, New Zealand, provides a natural laboratory for the investigation of the rheological behaviour of natural quartz under mid-lower crustal levels during transiently high stresses that are related to the upramping of the Pacific plate onto the Alpine Fault and followed by a stress drop. At depths >20 km, temperatures of 450-500° C, fluctuating fluid pressures of 310 MPa to 560 MPa (near lithostatic) and minimum strain rates of ~10^{-13 s-1, quartzofeldspathic wall rocks were faulted brittlely, presumably by aseismic stable sliding. Where brittle fault tips encounter older quartz veins embedded in the wall rocks, they terminate into shear zones in the quartz veins, deforming them brittlely and/or ductilely. Some embedded quartz veins deformed entirely ductilely to finite shear strains of 5-15. Despite these high strains and despite the smooth, coherent and ductile nature of the shearing of the veins, most of the ductilely sheared quartz veins show randomised or poorly developed CPO patterns. Most of the brittle faults are infilled by quartz-calcite veins indicating their role as conduits of fluids during deformation. We evaluate geological field observations such as deformed vein shape, scaling relationships between vein thickness and ductility and vein thickness distribution density and spacing of the brittle faults. Using finite element modelling, we simulate the observed vein structures in order to derive one or more flow laws that can explain the observed deformation for these naturally deformed quartz veins within the available time constraints and within the constraints of the known physical conditions. Two-dimensional models were set up and initially deformed to small finite strains in order to gain insight into the observed scaling relationship between the vein thickness and the proportional fraction of ductile creep strain (i. e. ductility of the quartz veins). The results show that

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

    USGS Publications Warehouse

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

    1990-01-01

    -northeast. Hydrothermal alteration of the host rocks consists of a widespread weak to moderately strong propylitic alteration and a more restricted sericitic alteration adjacent to the veins and shear zones. Sulfide minerals in the veins consist primarily of pyrite accompanied by lesser amounts of sphalerite, chalcopyrite, galena, acanthite, native silver, cerargyrite, and iodyrite in partly oxidized parts of the vein system. Gold is typically fine-grained, 1-20 microns, and occurs as native gold, electrum and gold-silver-telluride. Elements correlated with high gold concentrations include molybdenum, tellurium, bismuth, lead, silver, copper, zinc and arsenic. In Yap a similar vein system to that present in Palau is hosted by the Miocene Tomil Volcanics on the islands of Maap and Gagil Tamil. The quartz veins and quartz-cemented breccias contain up to 3.7 ppm gold and trace elements associated with the gold include tellurium, copper, silver and vanadium. Within the mineralized area an unusually iron-rich (3-20%), 4-m-thick, hot-spring deposit contains up to 1.04 ppm gold and high concentrations of tellurium, copper and vanadium. Hydrothermal eruption breccia beds are present within the deposit. The presence of the hot-spring deposit and banded and comb textures of the vein quartz suggest that the vein system presently exposed formed at a shallow level. The vein systems in Palau and Yap have similar textures, geochemical suites and alteration assemblages. Both vein systems formed late in the volcanic evolution of the intra-oceanic arc. Media tested for their effectiveness in geochemical exploration in the tropical, deeply weathered environment of Palau and Yap included stream sediments, heavy-mineral concentrates from stream sediments, and sediment from the mangrove coastal environment which is well developed around most of the islands of Yap and Palau. Geochemical surveys in both Yap and Palau of mangrove sediment show that adjacent to areas of gold mineralization, gold and tellu

  7. Varicose Veins and Other Vein Disorders

    MedlinePlus

    ... Share Glossary Basic Facts & Information Causes & Symptoms Diagnosis & Tests Care & Treatment Lifestyle & Management Other Resources Caregiving How To's Related Topics Peripheral Artery Disease Join our e-newsletter! Aging & Health A to Z Varicose Veins and Other ...

  8. Quartz crystal growth

    DOEpatents

    Baughman, Richard J.

    1992-01-01

    A process for growing single crystals from an amorphous substance that can undergo phase transformation to the crystalline state in an appropriate solvent. The process is carried out in an autoclave having a lower dissolution zone and an upper crystallization zone between which a temperature differential (.DELTA.T) is maintained at all times. The apparatus loaded with the substance, solvent, and seed crystals is heated slowly maintaining a very low .DELTA.T between the warmer lower zone and cooler upper zone until the amorphous substance is transformed to the crystalline state in the lower zone. The heating rate is then increased to maintain a large .DELTA.T sufficient to increase material transport between the zones and rapid crystallization. .alpha.-Quartz single crystal can thus be made from fused quartz in caustic solvent by heating to 350.degree. C. stepwise with a .DELTA.T of 0.25.degree.-3.degree. C., increasing the .DELTA.T to about 50.degree. C. after the fused quartz has crystallized, and maintaining these conditions until crystal growth in the upper zone is completed.

  9. The origin of vein-type copper-lead-zinc deposits Host in Palaeozoic metamorphic rocks at the Southeast Anatolian Orogenic Belt (Küplüce-Adıyaman, Southeastern Turkey)

    NASA Astrophysics Data System (ADS)

    Akyıldız, Mustafa; Yıldırım, Nail; Gören, Burcu; Yıldırım, Esra; Ilhan, Semiha

    2015-02-01

    The study area is located around the town of Küplüce between the Çelikhan and Sincik districts (Adıyaman, Turkey). Mineralisations are located at the Southeast Anatolian Orogenic Belt. Despite many differential units, especially in age and lithology, that coexist in the region, mineralisation and alteration are only developed in partly concordant/partly disconcordant veins/veinlets of quartz within chlorite schists, sericite schists, mica schists/mica gneisses, quartz schists and metadiabases of the Palaeozoic Pütürge metamorphics. Pyrite, chalcopyrite and sphalerite are dominant minerals in mineral paragenesis. Chalcocite, covellite and carollite are also found in trace amounts. Quartz, calcite, sericite and chlorite are the gang minerals. Silicification, sericitisation, chloritisation, epidotisation and limonitisation are widespread in limited areas around ore veins. The estimated Co/Ni (1.8-4.3) ratio in pyrites belonging to mineralisation deposits indicates that mineralisation in the region is related to magmatic hydrothermal deposits. In addition, REE (rare earth element) contents of mineralisation deposits in chondrite-normalised diagrams are enriched and show a similar trend to that of chondritic values. This indicates that metals that form mineralisation deposits are related to magmatic rocks. Values of δ34S estimated in the Küplüce region vary between 1.6‰ and 2.34‰. Values of δ34S close to 0 indicate that the sulphur forming the mineralisation is of magmatic origin. In addition, δ18O values vary between 8‰ and 10.8‰ and are consistent with magmatic water. Analyses of the fluid inclusions in quartz samples from mineralisation deposits were performed, and the homogenisation temperature was estimated to be between 90 and 150 °C. These temperature values can be explained by the mixing of a solution with surface water. It was determined that mineralisation deposits were vein-type hydrothermal deposits that had developed due to Middle Eocene

  10. Comparison of metasomatic reactions between a common CO2-rich vein fluid and diverse wall rocks: intensive variables, mass transfers, and Au mineralization at Alleghany, California

    USGS Publications Warehouse

    Böhlke, J.K.

    1989-01-01

    The gold deposits at Alleghany, California, are typical of many epigenetic gold-bearing hydrothermal vein systems in metamorphic terranes worldwide. Detailed analyses of alteration halos in serpentinite, mafic amphibolite, and granite wall rocks at Alleghany indicate that widely contrasting deposit types, ranging from fuchsite-carbonate schists to pyrite-albitites, resulted when different wall rocks interacted with the same externally derived CO2-rich hydrothermal vein fluid. Patterns of element redistribution within halos and among lithologic units suggest a complex process involving fluid flow along vein fractures and diffusion (?? infiltration) normal to the veins. Wall rocks locally controlled both the directions and magnitudes of chemical fluxes across vein walls. -from Author

  11. The compression pathway of quartz

    SciTech Connect

    Thompson, Richard M.; Downs, Robert T.; Dera, Przemyslaw

    2011-11-07

    The structure of quartz over the temperature domain (298 K, 1078 K) and pressure domain (0 GPa, 20.25 GPa) is compared to the following three hypothetical quartz crystals: (1) Ideal {alpha}-quartz with perfectly regular tetrahedra and the same volume and Si-O-Si angle as its observed equivalent (ideal {beta}-quartz has Si-O-Si angle fixed at 155.6{sup o}). (2) Model {alpha}-quartz with the same Si-O-Si angle and cell parameters as its observed equivalent, derived from ideal by altering the axial ratio. (3) BCC quartz with a perfectly body-centered cubic arrangement of oxygen anions and the same volume as its observed equivalent. Comparison of experimental data recorded in the literature for quartz with these hypothetical crystal structures shows that quartz becomes more ideal as temperature increases, more BCC as pressure increases, and that model quartz is a very good representation of observed quartz under all conditions. This is consistent with the hypothesis that quartz compresses through Si-O-Si angle-bending, which is resisted by anion-anion repulsion resulting in increasing distortion of the c/a axial ratio from ideal as temperature decreases and/or pressure increases.

  12. Mineralogical, fluid inclusion, and stable isotope constraints on mechanisms of ore deposition at the Samgwang mine (Republic of Korea)—a mesothermal, vein-hosted gold-silver deposit

    NASA Astrophysics Data System (ADS)

    Yoo, Bong Chul; Lee, Hyun Koo; White, Noel C.

    2010-02-01

    The Samgwang mine is located in the Cheongyang gold district (Cheonan Metallogenic Province) of the Republic of Korea. It consists of eight massive, gold-bearing quartz veins that filled NE- and NW-striking fractures along fault zones in Precambrian granitic gneiss of the Gyeonggi massif. Their mineralogy and paragenesis allow two separate vein-forming episodes to be recognized, temporally separated by a major faulting event. The ore minerals occur in quartz and calcite of stage I, associated with fracturing and healing of veins. Hydrothermal wall-rock alteration minerals of stage I include Fe-rich chlorite (Fe/(Fe+Mg) ratios 0.74-0.81), muscovite, illite, K-feldspar, and minor arsenopyrite, pyrite, and carbonates. Sulfide minerals deposited along with electrum during this stage include arsenopyrite, pyrite, pyrrhotite, sphalerite, marcasite, chalcopyrite, galena, argentite, pyrargyrite, and argentian tetrahedrite. Only calcite was deposited during stage II. Fluid inclusions in quartz contain three main types of C-O-H fluids: CO2-rich, CO2-H2O, and aqueous inclusions. Quartz veins related to early sulfides in stage I were deposited from H2O-NaCl-CO2 fluids (1,500-5,000 bar, average 3,200) with T htotal values of 200°C to 383°C and salinities less than about 7 wt.% NaCl equiv. Late sulfide deposition was related to H2O-NaCl fluids (140-1,300 bar, average 700) with T htotal values of 110°C to 385°C and salinities less than about 11 wt.% NaCl equiv. These fluids either evolved through immiscibility of H2O-NaCl-CO2 fluids as a result of a decrease in fluid pressure, or through mixing with deeply circulated meteoric waters as a result of uplift or unloading during mineralization, or both. Measured and calculated sulfur isotope compositions (δ34SH2S = 1.5 to 4.8‰) of hydrothermal fluids from the stage I quartz veins indicate that ore sulfur was derived mainly from a magmatic source. The calculated and measured oxygen and hydrogen isotope compositions (δ18OH2O

  13. Temporal relations of volcanism and hydrothermal systems in two areas of the Jemez volcanic field, New Mexico

    SciTech Connect

    WoldeGabriel, G.; Goff, F. )

    1989-11-01

    Two hydrothermal alteration events (8.07 Ma, one sample; 6.51-5.60 Ma, six samples) related to the waning stages of late Miocene volcanism ({ge} 13 to {le} 5.8 Ma) are recognized at the Cochiti district (southeast Jemez Mountains). Most of the K/Ar dates (0.83 {plus minus} 0.11-0.66 {plus minus} 0.21 Ma, four samples) in the hydrothermally altered, caldera-fill rocks of core hole VC-2A at Sulfur Springs, Valles caldera, indicate post-Valles caldera hydrothermal alteration. A sample from acid-altered landslide debris of postcaldera tuffs from the upper 13 m of the core hole was too young to be dated by the K/Ar method and is possibly associated with current hot-spring activity and the youngest pulses of volcanism. Oxygen-isotope data from illite/smectite clays in the Cochiti district are zonally distributed and range from {minus}2.15{per thousand} to {plus}7.97{per thousand} (SMOW), depending upon temperature, extent of rock-fluid interaction, and composition. The samples from VC-2A get lighter with depth ({minus}0.20{per thousand} to {plus}1.62{per thousand}). The K/Ar and oxygen-isotope data provide strong evidence that the epithermal quartz-vein-hosted gold-silver mineralization at Cochiti and the sub-ore grade molybdenite at VC-2A were deposited in the late Miocene (5.99-5.60 Ma) and mid-Quaternary ({approximately}0.66 Ma), respectively, by hydrothermal fluids composed primarily of meteoric water.

  14. Hydrothermal systems in two areas of the Jemez volcanic field: Sulphur Springs and the Cochiti mining district

    SciTech Connect

    WoldeGabriel, G.

    1989-03-01

    K/Ar dates and oxygen isotope data were obtained on 13 clay separates (<2 ..mu..m) of thermally altered mafic and silicic rocks from the Cochiti mining district (SE Jemez Mountains) and Continental Scientific Drilling Project (CSDP) core hole VC-2A (Sulphur Springs, Valles caldera). Illite with K/sub 2/O contents of 6.68%--10.04% is the dominant clay in the silicic rocks, whereas interstratified illite/smectites containing 1.4%--5.74% K/sub 2/O constitute the altered andesites. Two hydrothermal alteration events are recognized at the Cochiti area (8.07 m.y., n = 1, and 6.5--5.6 m.y., n = 6). The older event correlates with the waning stages of Paliza Canyon Formation andesite volcanism (greater than or equal to13 to less than or equal to8.5 m.y.), whereas the younger event correlates with intrusions and gold- and silver-bearing quartz veins associated with the Bearhead Rhyolite (7.54--5.8 m.y.). The majority of K/Ar dates in the hydrothermally altered, caldera-fill rocks of core hole VC-2A (0.83--0.66 m.y., n = 4) indicate that hydrothermal alteration developed contemporaneously with resurgence and ring fracture Valles Rhyolite domes (0.89--0.54 m.y.). One date of 0 +- 0.10 m.y. in acid-altered landslide debris of postcaldera tuffs from the upper 13 m of the core hole probably correlates with Holocene hydrothermal activity possibly associated with the final phases of the Valles Rhyolite (0.13 m.y.).

  15. Pyrite Recrystallization Experiments With Circulating Hydrothermal Solution

    NASA Astrophysics Data System (ADS)

    Isobe, H.; Abe, A.; Tanaka, K.

    2007-12-01

    Pyrite is one of the most common sulfide minerals found in hydrothermal deposits and sea-floor sediments from hydrothermal fumaroles. Hydrothermal fluid flow plays an important role in crystallization of sulfide minerals. In this study, we tried to reproduce pyrite crystallization with one-way flowing hydrothermal fluid. We designed a circuit circulating hydrothermal fluid by thermal convection. A rectangular circuit (42.6 cm by 17.3 cm) of SUS316 pressure tubes with 5 mm in inner diameter was used as a reaction vessel. In the circuit, pyrite dissolves to acidic fluid in upstream region. Then, pyrite will crystallize again in downstream region as temperature decreases. The rectangular plane was held to be 20 degrees inclination to generate thermal convection. One of the long sides of the rectangular was heated by an electric furnace. Starting materials were put in a tube to be heated. Upper half, approximately 20 cm, of the tube was filled with quartz sand. Next quarter was filled with equivalent mass mixture of quartz sand and powdered pyrite crystals. The lowest quarter was filled with mixture of quartz sand, pyrite, anhydrite and sulfur, those mass are equivalent. The solution was a mixture of 0.5mol/l HCl and 3.0mol/l NaCl. Maximum temperature was controlled to approximately 350°C at the center of the heated tube. Experimental durations were up to 9 days. Fluid pressure increased to approximately 6 MPa as heating. After the experiments, the run products were fixed with resin in a sample tube, and vertical sections were observed by SEM. In the run products, pyrite dissolved at the lower part of the starting material. In the upper half of the sample tube, pyrite crystals precipitated on quartz surface. Crystallization density depends on temperature gradient of the fluid. Predominant morphology of the pyrite crystals consists (100) plains. Tiny framboidal aggregates and crystals with (210) plains also occur. In the run products of longer than 3 days run durations

  16. Hydrothermal alteration in research drill hole Y-2, Lower Geyser Basin, Yellowstone National Park, Wyoming

    SciTech Connect

    Bargar, K.E.; Beeson, M.H.

    1981-05-01

    Y-2, a US Geological Survey research diamond-drill hole in Lower Geyser Basin, Yellowstone National Park, was drilled to a depth of 157.4 meters. The hole penetrated interbedded siliceous sinter and travertine to 10.2 m, glacial sediments of the Pinedale Glaciation interlayered with pumiceous tuff from 10.2 to 31.7 m, and rhyolitic lavas of the Elephant Back flow of the Central Plateau Member and the Mallard Lake Member of the Pleistocene Plateau Rhyolite from 31.7 to 157.4 m. Hydrothermal alteration is pervasive in most of the nearly continuous drill core. Rhyolitic glass has been extensively altered to clay and zeolite minerals (intermediate heulandite, clinoptilolite, mordenite, montmorillonite, mixed-layer illite-montmorillonite, and illite) in addition to quartz and adularia. Numerous veins, vugs, and fractures in the core contain these and other minerals: silica minerals (opal, ..beta..-cristobalite, ..cap alpha..-cristobalite, and chalcedony), zeolites (analcime, wairakite, dachiardite, laumontite, and yugawaralite), carbonates (calcite and siderite), clay (kaolinite and chlorite), oxides (hematite, goethite, manganite, cryptomelane, pyrolusite, and groutite), and sulfides (pyrhotite and pyrite) along with minor aegirine, fluorite, truscottite, and portlandite. Interbedded travertine and siliceous sinter in the upper part of the drill core indicate that two distinct types of thermal water are responsible for precipitation of the surficial deposits, and further that the water regime has alternated between the two thermal waters more than once since the end of the Pinedale Glaciation (approx. 10,000 years B.P.). Alternation of zones of calcium-rich and sodium- and potassium-rich hydrothermal minerals also suggests that the calcium-rich and sodium- and potassium-rich hydrothermal minerals also suggests that the water chemistry in this drill hole varies with depth.

  17. QUARTZ FIBER ELECTROSCOPES

    DOEpatents

    Henderson, R.P.

    1956-04-17

    This patent pertains to quartz fiber electroscopes of small size for use by personnel to monitor nuclear radiation. The invention resides tn a novel way of charging the electroscope whereby the charging of the electroscope whereby the charging of the electroscope is carried out without obtaining contact with the fiber system or its support and the electroscope can therefore be constructed without a protective cap to prevent wrongful discharge. The electroscope is charged by placing a voltage between an electrode located in close proximity to the element to be charged and the electroscope me metallic case. ABSTRACTS

  18. Hydrothermal Processes

    NASA Astrophysics Data System (ADS)

    German, C. R.; von Damm, K. L.

    2003-12-01

    What is Hydrothermal Circulation?Hydrothermal circulation occurs when seawater percolates downward through fractured ocean crust along the volcanic mid-ocean ridge (MOR) system. The seawater is first heated and then undergoes chemical modification through reaction with the host rock as it continues downward, reaching maximum temperatures that can exceed 400 °C. At these temperatures the fluids become extremely buoyant and rise rapidly back to the seafloor where they are expelled into the overlying water column. Seafloor hydrothermal circulation plays a significant role in the cycling of energy and mass between the solid earth and the oceans; the first identification of submarine hydrothermal venting and their accompanying chemosynthetically based communities in the late 1970s remains one of the most exciting discoveries in modern science. The existence of some form of hydrothermal circulation had been predicted almost as soon as the significance of ridges themselves was first recognized, with the emergence of plate tectonic theory. Magma wells up from the Earth's interior along "spreading centers" or "MORs" to produce fresh ocean crust at a rate of ˜20 km3 yr-1, forming new seafloor at a rate of ˜3.3 km2 yr-1 (Parsons, 1981; White et al., 1992). The young oceanic lithosphere formed in this way cools as it moves away from the ridge crest. Although much of this cooling occurs by upward conduction of heat through the lithosphere, early heat-flow studies quickly established that a significant proportion of the total heat flux must also occur via some additional convective process (Figure 1), i.e., through circulation of cold seawater within the upper ocean crust (Anderson and Silbeck, 1981). (2K)Figure 1. Oceanic heat flow versus age of ocean crust. Data from the Pacific, Atlantic, and Indian oceans, averaged over 2 Ma intervals (circles) depart from the theoretical cooling curve (solid line) indicating convective cooling of young ocean crust by circulating seawater

  19. ORIGIN OF QUARTZ IN COAL.

    USGS Publications Warehouse

    Ruppert, Leslie F.; Cecil, C. Blaine; Stanton, Ronald W.

    1984-01-01

    Both a scanning electron microscope and an electron microprobe (EMP) were used in this study to analyze the cathodoluminescence properties of quartz grains in samples of the Upper Freeport coal bed because quartz grains in coal are small (silt sized) and below the resolution capabilities of a standard luminoscope. Quartz grains were identified by the detection of silicon alone with energy dispersive X-ray units attached to both the SEM and the EMP.

  20. Crustal faults exposed in the Pito Deep Rift: Conduits for hydrothermal fluids on the southeast Pacific Rise

    NASA Astrophysics Data System (ADS)

    Hayman, Nicholas W.; Karson, Jeffrey A.

    2009-02-01

    The escarpments that bound the Pito Deep Rift (northeastern Easter microplate) expose in situ upper oceanic crust that was accreted ˜3 Ma ago at the superfast spreading (˜142 mm/a, full rate) southeast Pacific Rise (SEPR). Samples and images of these escarpments were taken during transects utilizing the human-occupied vehicle Alvin and remotely operated vehicle Jason II. The dive areas were mapped with a "deformation intensity scale" revealing that the sheeted dike complex and the base of the lavas contain approximately meter-wide fault zones surrounded by fractured "damage zones." Fault zones are spaced several hundred meters apart, in places offset the base of the lavas, separate areas with differently oriented dikes, and are locally crosscut by (younger) dikes. Fault rocks are rich in interstitial amphibole, matrix and vein chlorite, prominent veins of quartz, and accessory grains of sulfides, oxides, and sphene. These phases form the fine-grained matrix materials for cataclasites and cements for breccias where they completely surround angular to subangular clasts of variably altered and deformed basalt. Bulk rock geochemical compositions of the fault rocks are largely governed by the abundance of quartz veins. When compositions are normalized to compensate for the excess silica, the fault rocks exhibit evidence for additional geochemical changes via hydrothermal alteration, including the loss of mobile elements and gain of some trace metals and magnesium. Microstructures and compositions suggest that the fault rocks developed over multiple increments of deformation and hydrothermal fluid flow in the subaxial environment of the SEPR; faults related to the opening of the Pito Deep Rift can be distinguished by their orientation and fault rock microstructure. Some subaxial deformation increments were likely linked with violent discharge events associated with fluid pressure fluctuations and mineral sealing within the fault zones. Other increments were linked with

  1. Varicose veins and venous insufficiency

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/001109.htm Varicose veins and venous insufficiency To use the sharing features on this page, please enable JavaScript. Varicose veins are swollen, twisted, and enlarged veins that you ...

  2. Silica Transport and Distribution in Saline, Immiscible Fluids: Application to Subseafloor Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Steele-Macinnis, M.; Bodnar, R. J.; Lowell, R.; Rimstidt, J. D.

    2009-05-01

    Quartz is a nearly ubiquitous gangue mineral in hydrothermal mineral deposits, most often constituting the bulk of hydrothermal mineralization. The dissolution, transport and precipitation of quartz is controlled by the solubility of silica; in particular, in hot hydrothermal fluids in contact with quartz, silica saturation can generally be assumed, as rates of dissolution and precipitation are generally much faster than fluid flow rates. The solubility of silica in aqueous fluids can be used to understand the evolution of hydrothermal systems by tracing the silica distribution in these systems through time. The solubility of quartz in an aqueous fluid is dependent upon the pressure, temperature and composition (PTX) of the fluid. Silica solubility in pure water as a function of pressure and temperature is well understood. However, natural fluids contain variable amounts of dissolved ionic species, thus it is necessary to include the effects of salinity on silica solubility to accurately predict quartz distribution in hydrothermal systems. In particular, addition of NaCl results in enhanced quartz solubility over a wide range of PT conditions. Furthermore, if phase separation occurs in saline fluids, silica is preferentially partitioned into the higher salinity brine phase; if vapor is removed from the system, the bulk salinity in the system evolves towards the brine end member, and overall silica solubility is enhanced. There is abundant evidence from natural fluid inclusions for fluid immiscibility in hydrothermal ore deposits. Additionally, recent hydrothermal models that include fluid phase equilibria effects predict that phase separation may be an important control on the distribution of dissolved components in seafloor hydrothermal systems. An empirical equation describing the solubility of silica in salt-bearing hydrothermal solutions over a wide range of PTX conditions has been incorporated into a multiphase fluid flow model for seafloor hydrothermal

  3. Quartz resonator processing system

    DOEpatents

    Peters, Roswell D. M.

    1983-01-01

    Disclosed is a single chamber ultra-high vacuum processing system for the oduction of hermetically sealed quartz resonators wherein electrode metallization and sealing are carried out along with cleaning and bake-out without any air exposure between the processing steps. The system includes a common vacuum chamber in which is located a rotatable wheel-like member which is adapted to move a plurality of individual component sets of a flat pack resonator unit past discretely located processing stations in said chamber whereupon electrode deposition takes place followed by the placement of ceramic covers over a frame containing a resonator element and then to a sealing stage where a pair of hydraulic rams including heating elements effect a metallized bonding of the covers to the frame.

  4. Dual quartz crystal microbalance

    SciTech Connect

    Dunham, G.C.; Benson, N.H.; Petelenz, D.; Janata, J. )

    1995-01-15

    Construction and performance of a dual quartz crystal microbalance is described. The final probe has a dipstick configuration that is particularly suitable for sensing and monitoring applications in viscous and/or conducting liquids. The differential (heterodyned) frequency measurement substantially eliminates the deleterious effects of viscosity, temperature, and conductivity. The corresponding performance coefficients are temperature df/dT = 1.5 Hz/[degree]C, viscosity df/d[eta][sub L] = 103 Hz/cP, and conductivity df/dM = 108 Hz/M, where conductivity is expressed in terms of molarity of sodium chloride. As an example, the etching of a 2000-A-thick layer of aluminum has been monitored as a function of time. 13 refs., 8 figs., 1 tab.

  5. Hydrothermal mineralogy and fluid inclusions chemistry to understand the roots of active geothermal systems

    NASA Astrophysics Data System (ADS)

    Chambefort, I. S.; Dilles, J. H.; Heinrich, C.

    2013-12-01

    An integrated study to link magmatic textures, magmatic mineral compositions, hydrothermal alteration zoning, hydrothermal mineral chemistry, and fluid inclusion compositions has been undertaken to link an intrusive complex and its degassing alteration halo with their surface equivalent in an active geothermal system. Ngatamariki geothermal system, New Zealand, presents a unique feature in the Taupo Volcanic Zone (TVZ). Drilling intercepted an intrusive complex with a high temperature alteration halo similarly to what is observed in magmatic-derived ore deposits. Thus it presents the perfect opportunity to study the magmatic-hydrothermal transition of the TVZ by characterizing the nature of the deep magmatic fluids link to the heat source of the world known geothermal fields. The record of magmatic-hydrothermal fluid-rock interactions preserved at Ngatamariki may be analogous of processes presently occurring at depth beneath TVZ geothermal systems. The intrusive complex consists of over 5 km3 of tonalite, diorite, basalt and aplitic dykes. Evidence of undercooling subsolidus magmatic textures such as myrmekite and skeletal overgrowth are commonly observed and often linked to volatile loss. The fluids released during the crystallization of the intrusive complex are interpreted to be at the origin of the surrounding high temperature alteration halo. Advanced argillic to potassic alteration and high temperature acidic assemblage is associated with high-temperature quartz veining at depth and vuggy silica at the paleo-surface. Major element compositions of the white micas associated with the high temperature halo show a transition from, muscovite to phengite, muscovitic illite away from the intrusion, with a transition to pyrophyllite and/ or topaz, and andalusite characteristic of more acidic conditions. Abundant high-density (up to 59 wt% NaCl eq and homogenization temperatures of 550 degree Celsius and above) coexist with low-density vapor fluid inclusions. This

  6. HYDROTHERMAL MINERALOGY OF RESEARCH DRILL HOLE Y-3, YELLOWSTONE NATIONAL PARK, WYOMING.

    USGS Publications Warehouse

    Bargar, Keith E.; Beeson, Melvin H.

    1984-01-01

    The approximate paragenetic sequence of hydrothermal minerals in the Y-3 U. S. Geological Survey research diamond-drill hole in Lower Geyser Basin, Yellowstone National Park, Wyoming, is: hydrothermal chalcedony, hematite, pyrite, quartz, clay minerals (smectite and mixed-layer illite-smectite), calcite, chlorite, fluorite, pyrite, quartz, zeolite minerals (analcime, dachiardite, laumontite, stilbite, and yugawaralite), and clay minerals (smectite and mixed-layer illite-smectite). A few hydrothermal minerals that were identified in drill core Y-3 (lepidolite, aegirine, pectolite, and truscottite) are rarely found in modern geothermal areas. The alteration minerals occur primarily as vug and fracture fillings that were deposited from cooling thermal water. Refs.

  7. Mixing of fluids in hydrothermal ore-forming (Sn,W) systems: stable isotope and rare earth elements data

    NASA Astrophysics Data System (ADS)

    Sushchevskaya, T. M.; Popova, J. A.; Velivetskaya, T. A.; Ignatiev, A. V.; Matveeva, S. S.; Limantseva, O. A.

    2012-04-01

    Experimental and physico-chemical modeling data witness to important role of mixing of different type of fluids during tin and tungsten ore formation in hydrothermal systems. Mixing of magmatogeneous fluids, exsolved from granite melts, with exogenic, initially meteoric waters in hydrothermal ore-forming systems may change chemical composition of ore-forming fluid, causing cassiterite and/or wolframite precipitation (Heinrich, 1990; Sushchevskaya, Ryzhenko, 2002). We studied the process of genetically different fluids mixing for two economic Sn-W deposits, situated in the Iultin ore region (North-East of Russia, Chukotka Penninsula). The Iultin and Svetloe deposits are located in the apical parts of close situated leucogranite stocks, formed at the final stage of the Iultin complex emplacement. Both deposits are composed of a series of quartz veins among the flyschoid rocks (T 1-2), cut by the dikes (K1) of lamprophyre, granodiorite porphyre and alpite. The veins of the deposits are dominated by the productive quartz-wolframite-cassiterite-arsenopyrite-muscovite mineral assemblage. Topaz, beryl, fluorite, and albite occur sporadically. The later sulfide (loellingite-stannite-chalcopyrite) and quartz-fluorite-calcite assemblages show insignificant development. The preore quartz veinlets in host hornfels contain disseminated iron sulfides, chalcopyrite, muscovite. Isotopic (H, O, Ar) study of minerals, supplemented by oxygen isotope data of host granites and metamorphic rocks gave us possibility to conclude, that at the Iultin and the Svetloye deposits fluid mixing was fixed on the early stages of deposit formation and could be regarded as probable cause of metal (W, Sn) precipitation. During postore time the intensive involvement of isotopically light exogenic waters have changed: a) the initial character of oxygen isotope zonality; b) the initial hydrogen isotope composition of muscovites, up to meteoric calculated values for productive fluid (while the δ18O

  8. Contrasting hydrological processes of meteoric water incursion during magmatic-hydrothermal ore deposition: An oxygen isotope study by ion microprobe

    NASA Astrophysics Data System (ADS)

    Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Bouvier, Anne-Sophie; Baumgartner, Lukas; Heinrich, Christoph A.

    2016-10-01

    Meteoric water convection has long been recognized as an efficient means to cool magmatic intrusions in the Earth's upper crust. This interplay between magmatic and hydrothermal activity thus exerts a primary control on the structure and evolution of volcanic, geothermal and ore-forming systems. Incursion of meteoric water into magmatic-hydrothermal systems has been linked to tin ore deposition in granitic plutons. In contrast, evidence from porphyry copper ore deposits suggests that crystallizing subvolcanic magma bodies are only affected by meteoric water incursion in peripheral zones and during late post-ore stages. We apply high-resolution secondary ion mass spectrometry (SIMS) to analyze oxygen isotope ratios of individual growth zones in vein quartz crystals, imaged by cathodo-luminescence microscopy (SEM-CL). Existing microthermometric information from fluid inclusions enables calculation of the oxygen isotope composition of the fluid from which the quartz precipitated, constraining the relative timing of meteoric water input into these two different settings. Our results confirm that incursion of meteoric water directly contributes to cooling of shallow granitic plutons and plays a key role in concurrent tin mineralization. By contrast, data from two porphyry copper deposits suggest that downward circulating meteoric water is counteracted by up-flowing hot magmatic fluids. Our data show that porphyry copper ore deposition occurs close to a magmatic-meteoric water interface, rather than in a purely magmatic fluid plume, confirming recent hydrological modeling. On a larger scale, the expulsion of magmatic fluids against the meteoric water interface can shield plutons from rapid convective cooling, which may aid the build-up of large magma chambers required for porphyry copper ore formation.

  9. Lithium isotope traces magmatic fluid in a seafloor hydrothermal system.

    PubMed

    Yang, Dan; Hou, Zengqian; Zhao, Yue; Hou, Kejun; Yang, Zhiming; Tian, Shihong; Fu, Qiang

    2015-01-01

    Lithium isotopic compositions of fluid inclusions and hosted gangue quartz from a giant volcanogenic massive sulfide deposit in China provide robust evidence for inputting of magmatic fluids into a Triassic submarine hydrothermal system. The δ(7)Li results vary from +4.5‰ to +13.8‰ for fluid inclusions and from +6.7‰ to +21.0‰ for the hosted gangue quartz(9 gangue quartz samples containing primary fluid inclusions). These data confirm the temperature-dependent Li isotopic fractionation between hydrothermal quartz and fluid (i.e., Δδ(7)Liquartz-fluid = -8.9382 × (1000/T) + 22.22(R(2) = 0.98; 175 °C-340 °C)), which suggests that the fluid inclusions are in equilibrium with their hosted quartz, thus allowing to determine the composition of the fluids by using δ(7)Liquartz data. Accordingly, we estimate that the ore-forming fluids have a δ(7)Li range from -0.7‰ to +18.4‰ at temperatures of 175-340 °C. This δ(7)Li range, together with Li-O modeling , suggest that magmatic fluid played a significant role in the ore formation. This study demonstrates that Li isotope can be effectively used to trace magmatic fluids in a seafloor hydrothermal system and has the potential to monitor fluid mixing and ore-forming process. PMID:26347051

  10. Lithium isotope traces magmatic fluid in a seafloor hydrothermal system

    NASA Astrophysics Data System (ADS)

    Yang, Dan; Hou, Zengqian; Zhao, Yue; Hou, Kejun; Yang, Zhiming; Tian, Shihong; Fu, Qiang

    2015-09-01

    Lithium isotopic compositions of fluid inclusions and hosted gangue quartz from a giant volcanogenic massive sulfide deposit in China provide robust evidence for inputting of magmatic fluids into a Triassic submarine hydrothermal system. The δ7Li results vary from +4.5‰ to +13.8‰ for fluid inclusions and from +6.7‰ to +21.0‰ for the hosted gangue quartz(9 gangue quartz samples containing primary fluid inclusions). These data confirm the temperature-dependent Li isotopic fractionation between hydrothermal quartz and fluid (i.e., Δδ7Liquartz-fluid = -8.9382 × (1000/T) + 22.22(R2 = 0.98 175 °C-340 °C)), which suggests that the fluid inclusions are in equilibrium with their hosted quartz, thus allowing to determine the composition of the fluids by using δ7Liquartz data. Accordingly, we estimate that the ore-forming fluids have a δ7Li range from -0.7‰ to +18.4‰ at temperatures of 175-340 °C. This δ7Li range, together with Li-O modeling , suggest that magmatic fluid played a significant role in the ore formation. This study demonstrates that Li isotope can be effectively used to trace magmatic fluids in a seafloor hydrothermal system and has the potential to monitor fluid mixing and ore-forming process.

  11. The N story of a hydrothermal Acheaen BIF-bearing chert

    NASA Astrophysics Data System (ADS)

    Wagner, C.; Orberger, B.; Pinti, D. L.; Gallien, J.; Fialin, M.; Daudin, L.; Hashizume, K.

    2004-05-01

    N isotopes in rocks can trace past biological activity, but it implies a deep knowledge of the N trapping sites and of the associated geo-biochemical N fractionation processes. The studied chert (PB 458) belongs to the 3.2 Ga Marble Bar complex, Pilbara, Western Australia. Isotopic analyses showed two N components with d15N of 6.7±1.6% and 10.0±1.6%, respectively. New mineralogical and REE analyses distinguished three microenvironments: 1) a silicified basalt having preserved its porphyric texture, with euhedral hydrothermal Fe-sulfides precipitated in the protomafic minerals; (2) Fe-Mn oxyhydroxide (BIFs) laminae and associated Ni-Cu-Mn-Au-Pd alloys and HREE-Y phosphates alternate with cryptocrystalline quartz, hosting magnetite inclusions. BIFs are initially composed of magnetite and carbonates, segregated from a Fe-Ca-Mg-enriched fluid, resulting from water-basalt interaction; (3) massive cryptocrystalline quartz with interstitial K-feldspar, Ba-K-mica and Fe-sulfides representing the residual fluids. K-Al-silicates incorporated 130 to 2540 ppm of N, probably NH4+ and 2990 to 6970 ppm of C from hydrothermal fluids. Oxidizing and slightly acid fluids later infiltrated the chert, and quartz veins were formed during diagenesis. Goethite and hydrous Mn-Fe minerals replaced carbonates, sulfides and magnetite, incorporating 500 to 4550 ppm of N and 3440 to 6000 ppm of C. N might occur as NH4+, replacing K+ in the Fe-Mn oxyhyroxide structure. The oxyhydroxide texture is vermicular and filamentous Their heterogeneous chemical composition is caused possibly by microbial activity. This is in agreement with measured N/C ratios of 0.06-0.6, similar to those known for marine bacteria. The d15N signatures of N are similar to those measured in marine sediments and derived from metabolic activity of bacteria (d15N=7.6%). The higher measured d15N values of 10% could be due to post-emplacement devolatilization of the sample or alternatively to different redox conditions during

  12. The physical hydrology of magmatic-hydrothermal systems: High-resolution 18O records of magmatic-meteoric water interaction from the Yankee Lode tin deposit (Mole Granite, Australia)

    NASA Astrophysics Data System (ADS)

    Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Heinrich, Christoph A.; Baumgartner, Lukas; Bouvier, Anne-Sophie

    2016-04-01

    Magmatic-hydrothermal ore deposits are important economic Cu, Au, Mo and Sn resources (Sillitoe, 2010, Kesler, 1994). The ore formation is a result of superimposed enrichment processes and metals can precipitate due to fluid-rock interaction and/or temperature drop caused by convection or mixing with meteoric fluid (Heinrich and Candela 2014). Microthermometry and LA-ICP MS trace element analyses of fluid inclusions of a well-characterized quartz sample from the Yankee Lode quartz-cassiterite vein deposit (Mole Granite, Australia) suggest that tin precipitation was driven by dilution of hot magmatic water by meteoric fluids (Audétat et al.1998). High resolution in situ oxygen isotope measurements of quartz have the potential to detect changing fluid sources during the evolution of a hydrothermal system. We analyzed the euhedral growth zones of this previously well-studied quartz sample. Growth temperatures are provided by Audétat et al. (1998) and Audétat (1999). Calculated δ 18O values of the quartz- and/or cassiterite-precipitating fluid show significant variability through the zoned crystal. The first and second quartz generations (Q1 and Q2) were precipitated from a fluid of magmatic isotopic composition with δ 18O values of ˜ 8 - 10 ‰. δ 18O values of Q3- and tourmaline-precipitating fluids show a transition from magmatic δ 18O values of ˜ 8 ‰ to ˜ -5 ‰. The outermost quartz-chlorite-muscovite zone was precipitated from a fluid with a significant meteoric water component reflected by very light δ 18O values of about -15 ‰ which is consistent with values found by previous studies (Sun and Eadington, 1987) using conventional O-isotope analysis of veins in the distal halo of the granite intrusion. Intense incursion of meteoric water during Q3 precipitation (light δ 18O values) agrees with the main ore formation event, though the first occurrence of cassiterite is linked to Q2 precipitating fluid with magmatic-like isotope signature. This

  13. Retinal vein occlusion

    MedlinePlus

    ... Berrocal MH, Rodriguez FJ, et al. Pan-American Collaborative Retina Study Group (PACORES). Comparison of two doses ... retinal vein occlusion: results from the Pan-American Collaborative Retina Study Group at 6 months of follow- ...

  14. Deep vein thrombosis - discharge

    MedlinePlus

    You were treated for deep venous thrombosis (DVT). This is a condition in which a blood clot forms in a vein that is not on ... especially if it gets worse upon taking a deep breath in You cough up blood

  15. Popliteal vein aneurysm.

    PubMed

    Falkowski, A; Poncyljusz, W; Zawierucha, D; Kuczmik, W

    2006-06-01

    The incidence of a popliteal vein aneurysm is extremely low. Two cases of this rare venous anomaly are described. The epidemiology, morphology, and diagnostic methods are discussed and the potentially dangerous complications and treatment methods are presented. PMID:16796307

  16. Quartz crystal fabrication facility

    NASA Astrophysics Data System (ADS)

    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.

  17. Field guide to hydrothermal alteration in the White River altered area and in the Osceola Mudflow, Washington

    USGS Publications Warehouse

    John, David A.; Rytuba, James J.; Ashley, Roger P.; Blakely, Richard J.; Vallance, James W.; Newport, Grant R.; Heinemeyer, Gary R.

    2003-01-01

    The Cenozoic Cascades arcs of southwestern Washington are the product of long-lived, but discontinuous, magmatism beginning in the Eocene and continuing to the present (for example, Christiansen and Yeats, 1992). This magmatism is the result of subduction of oceanic crust beneath the North American continent. The magmatic rocks are divided into two subparallel, north-trending continental-margin arcs, the Eocene to Pliocene Western Cascades, and the Quaternary High Cascades, which overlies, and is east of, the Western Cascades. Both arcs are calc-alkaline and are characterized by voluminous mafic lava flows (mostly basalt to basaltic andesite compositions) and scattered large stratovolcanoes of mafic andesite to dacite compositions. Silicic volcanism is relatively uncommon. Quartz diorite to granite plutons are exposed in more deeply eroded parts of the Western Cascades Arc (for example, Mount Rainier area and just north of Mt. St. Helens). Hydrothermal alteration is widespread in both Tertiary and Quaternary igneous rocks of the Cascades arcs. Most alteration in the Tertiary Western Cascades Arc resulted from hydrothermal systems associated with small plutons, some of which formed porphyry copper and related deposits, including copper-rich breccia pipes, polymetallic veins, and epithermal gold-silver deposits. Hydrothermal alteration also is present on many Quaternary stratovolcanoes of the High Cascades Arc. On some High Cascades volcanoes, this alteration resulted in severely weakened volcanic edifices that were susceptible to failure and catastrophic landslides. Most notable is the sector collapse of the northeast side of Mount Rainier that occurred about 5,600 yr. B.P. This collapse resulted in formation of the clay-rich Osceola Mudflow that traveled 120 km down valley from Mount Rainier to Puget Sound covering more than 200 km2. This field trip examines several styles and features of hydrothermal alteration related to Cenozoic magmatism in the Cascades arcs

  18. Hydrogen speciation in synthetic quartz

    USGS Publications Warehouse

    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.

  19. Hydrothermal macroscopic Fe-sepiolite from Oujda Mounts (Middle Atlas, Eastern Morocco)

    NASA Astrophysics Data System (ADS)

    Arranz, Enrique; Lago, Marceliano; Bastida, Joaquín; Galé, Carlos; Soriano, Jesús; Ubide, Teresa

    2008-10-01

    The Triassic-Jurassic series in the Oujda Mounts (Middle Atlas, NE Morocco) includes two basaltic units. The whole sequence is crosscut by veins filled with Fe-sepiolite + chalcedony + calcite + smectite and mixed layer talc-saponite. Fe-sepiolite occurs as macroscopic fibres and is one of the latest mineral phases in the filling sequence of the veins. The compositional relationships and crystallographic parameters obtained on carefully selected samples of sepiolite are compared with previous data, and support the actual development of Mg-Fe substitution in this clay mineral, given the adequate hydrothermal conditions. Genesis of this uncommon variety of sepiolite in veins is interpreted as the result of regional low temperature hydrothermalism that affected the Middle Atlas during the Jurassic. The Mg-rich hydrothermal solutions interacted with the basaltic sequences, previously affected by alteration processes, producing the mobilization of Fe and allowing for the precipitation of Fe-sepiolite as a late mineral in the veins.

  20. Geology and mineralogy of the Santo Nino Ag-Pb-Zn vein, Fresnillo District, Mexico

    SciTech Connect

    Gemmell, J.B.; Zantop, H.; Birnie, R.W.

    1985-01-01

    The Santo Nino Ag-Pb-Zn vein is the major producer of the Fresnillo District, located 750 km NW of Mexico City. It is over 2.4 km long, more than 480 m in vertical extent, more than 2.5 m wide overall, and has average grades of >600 gm/t Ag and <2% combined Pb and Zn. The vein is hosted by a tilted sequence of Cretaceous graywackes, shales and andesitic volcanics and extends upward into a Lower Tertiary conglomerate. Up to 5 separate opening events occurred along the vein, resulting in discontinuous stages of brecciation and crustiform banding. Ore mineral zonation is well developed both vertically and laterally and closely reflects metal and metal ratio distributions. Ore minerals are sphalerite, galena, pyrite, chalcopyrite, arsenopyrite, marcasite, pyrrhotite, acanthite, native silver, and three coexisting solid solution series, pyrargyrite-proustite, polybasite-arsenopolybasite, and tetrahedrite-tennantite in a gangue of quartz, calcite, clay, sericite,and chlorite. A 5-stage paragenetic sequence can be established: 1) pyrite, arsenopyrite, quartz, 2) sphalerite, galena, chalcopyrite, quartz, 3) tetrahedrite, pyrargyrite, polybasite, quartz, 4) acanthite, native silver, calcite, quartz, and 5) calcite. Preliminary microprobe analyses indicate that the Ag-rich solid solution series are Sb-rich in the central and upper portions of the vein and As-rich at deeper levels.

  1. Evidence of Nb-Ta mobility in high temperature F-rich fluids evidenced by the La Bosse quartz-Nb-ferberite stockwork (Echassières, French Massif Central).

    NASA Astrophysics Data System (ADS)

    Marignac, C.; Cuney, M.

    2012-04-01

    ). Thus the unusual Nb content of the La Bosse ferberites is correlated to the apparently very distal setting of this quartz system relatively to the parent granite, in contrast with most quartz-W systems in the French Massif Central (Aïssa et al. 1987). When invaded by aplites or aplopegmatites, the ferberite-bearing quartz veins are dissolved, but the ferberites remain apparently unaffected - they are not dissolved by the granite melt. Yet, the acicular and lanceolate crystals have lost their Nb-zoning and display uniform homogenised Nb content. The emplacement of the Beauvoir granite was associated with late magmatic exsolution of an Al- and F-rich, silica undersaturated, hydrothermal fluid that percolated upwards in the surrounding schists (Cuney et al. 1992). When interacting with the quartz veins of the La Bosse stockwork, this fluid precipitated topazites. Again, included ferberites remain apparently unaffected. However, they display microscopic vuggy cavities, successively filled by a Nb-rich ferberite (up to 8.91% Nb2O5) with significant Ta content (up to 0.35 % Ta2O5), a wolframo-ixiolite and a Ta-rich columbite. Later Li-phengite was precipitated from the same magmatic fluid, and was associated with hubnerite enrichment of pre-existing ferberites along Li-phengite-bearing microcracks (down to 0.20 mole % Fb). Ta and Nb are known for their poor solubility in hydrothermal fluids, but the Nb and Ta enrichments observed in the wolframite of La Bosse stockwork show that they can be transported to some extent by F-rich fluids. Aïssa, M., Marignac, C., Weisbrod, A. (1987). Le stockwerk à ferbérite d'Echassières : évolution spatiale et temporelle; cristallochimie des ferbérites. In : Cuney, M., Autran, A. (eds), Echassières : le forage scientifique d'Echassières (Allier). Une clé pour la compréhension des mécanismes magmatiques et hydrothermaux associés aux granites à métaux rares. Mém. GPF, tome 1, 311-334. M Cuney, C Marignac, A Weisbrod (1992). The

  2. Evidence of Nb-Ta mobility in high temperature F-rich fluids evidenced by the La Bosse quartz-Nb-ferberite stockwork (Echassières, French Massif Central).

    NASA Astrophysics Data System (ADS)

    Marignac, C.; Cuney, M.

    2012-04-01

    ). Thus the unusual Nb content of the La Bosse ferberites is correlated to the apparently very distal setting of this quartz system relatively to the parent granite, in contrast with most quartz-W systems in the French Massif Central (Aïssa et al. 1987). When invaded by aplites or aplopegmatites, the ferberite-bearing quartz veins are dissolved, but the ferberites remain apparently unaffected - they are not dissolved by the granite melt. Yet, the acicular and lanceolate crystals have lost their Nb-zoning and display uniform homogenised Nb content. The emplacement of the Beauvoir granite was associated with late magmatic exsolution of an Al- and F-rich, silica undersaturated, hydrothermal fluid that percolated upwards in the surrounding schists (Cuney et al. 1992). When interacting with the quartz veins of the La Bosse stockwork, this fluid precipitated topazites. Again, included ferberites remain apparently unaffected. However, they display microscopic vuggy cavities, successively filled by a Nb-rich ferberite (up to 8.91% Nb2O5) with significant Ta content (up to 0.35 % Ta2O5), a wolframo-ixiolite and a Ta-rich columbite. Later Li-phengite was precipitated from the same magmatic fluid, and was associated with hubnerite enrichment of pre-existing ferberites along Li-phengite-bearing microcracks (down to 0.20 mole % Fb). Ta and Nb are known for their poor solubility in hydrothermal fluids, but the Nb and Ta enrichments observed in the wolframite of La Bosse stockwork show that they can be transported to some extent by F-rich fluids. Aïssa, M., Marignac, C., Weisbrod, A. (1987). Le stockwerk à ferbérite d'Echassières : évolution spatiale et temporelle; cristallochimie des ferbérites. In : Cuney, M., Autran, A. (eds), Echassières : le forage scientifique d'Echassières (Allier). Une clé pour la compréhension des mécanismes magmatiques et hydrothermaux associés aux granites à métaux rares. Mém. GPF, tome 1, 311-334. M Cuney, C Marignac, A Weisbrod (1992). The

  3. Evolution of ore forming fluid in the orogenic type gold deposit in Tavt, Mongolia: trace element geochemistry and fluid inclusions in quartz

    NASA Astrophysics Data System (ADS)

    Lee, K.; Oyungerel, S.; Lee, I.

    2011-12-01

    The Tavt gold deposit of Dzhida-Selengisky metallogenic belt is located in the Dzhida terrane, northern Mongolia. This deposit commonly occurs with massive auriferous quartz veins that contain sulfides and less commonly occurs with disseminated- and stockwork-type quartz veins. Such gold-bearing quartz veins have an average grade of 6.3 g/t Au, 29.4 g/t Ag, and 1.3% Cu. This gold deposit is composed of three stages of quartz vein groups. The first stage quartz group is widely spread with medium to large grain size, showing white-grey and milky white colors. It underwent intensive cataclasis with strong cuts via fractures and includes a small amount of sulfides, secondary minerals and Au. The second stage quartz group is grey and includes an oxidation zone. The oxidation zone distributed on the outside of the vein is brown and green-grey; it is also enriched with sulfide minerals containing gold. This quartz group is located in a brittle and cataclastic zone with the first stage quartz group. The main mineralization process for gold is related to this second stage quartz group. The transition between the first and second groups is not clear, and their contact relationship is complex. The third stage quartz group is transparent to translucent, and has small euhedral crystals that were formed in the second stage quartz group. The third stage of quartz is partly associated with chlorite and montmorillonite that was formed in the latest stage. Each generation of quartz was analyzed by SEM-CL, EPMA, and ICP-MS. Fluid inclusion data were collected from the USGS gas-flow heating/freezing stage and Raman-spectroscopy. The electron microprobe data show the distribution of Al, Ca, K and Fe among distinguished CL intensities and textures of quartz from different stages. The prepared pure quartz samples were analyzed by ICP-MS. The analysis also shows different patterns of trace elements according to the quartz stages.

  4. Hydrothermal Manganese Mineralization Near the Samoan Hotspot

    NASA Astrophysics Data System (ADS)

    Hein, J. R.; Staudigel, H.; Koppers, A.; Hart, S. R.; Dunham, R.

    2006-12-01

    erosional or mass wasting events; subsequently a thin layer of hydrogenetic Fe-Mn oxides accreted on the exposed surface. Mn-oxide filled veins may represent part of a feeder system. The thick sediment-free Mn-oxide layers locally grade into Mn-oxide cemented volcaniclastic beds. Our results indicate the extensive production of hydrothermal Mn on a regional basis, probably from multiple hydrothermal sources within the Samoan chain, and from the Tonga arc/back-arc system immediately to the west, as determined in previous studies.

  5. Xenopumice erupted on 15 October 2011 offshore of El Hierro (Canary Islands): a subvolcanic snapshot of magmatic, hydrothermal and pyrometamorphic processes

    NASA Astrophysics Data System (ADS)

    Del Moro, S.; Di Roberto, A.; Meletlidis, S.; Pompilio, M.; Bertagnini, A.; Agostini, S.; Ridolfi, F.; Renzulli, A.

    2015-06-01

    On 15 October 2011, a submarine eruption offshore of El Hierro Island gave rise to floating volcanic products, known as xenopumices, i.e., pumiceous xenoliths partly mingled and coated with the juvenile basanitic magma. Over the last few years, no consensus in the scientific community in explaining the origin of these products has been reached. In order to better understand the formation of xenopumice, we present a textural, mineralogical, and geochemical study of the possible magmatic, hydrothermal, and pyrometamorphic processes, which usually operate in the plumbing systems of active volcanoes. We carried out a comprehensive SEM investigation and Sr-Nd-Pb isotope analyses on some samples representative of three different xenopumice facies. All the data were compared with previous studies, new data for El Hierro extrusives and a literature dataset of Canary Islands igneous and sedimentary rocks. In the investigated xenopumices, we emphasize the presence of restitic magmatic phases as well as crystallization of minerals (mainly olivine + pyroxene + magnetite aggregates) as pseudomorphs after pre-existing mafic phenocrysts, providing evidence of pyrometamorphism induced by the high-T juvenile basanitic magma. In addition, we identify veins consisting of zircon + REE-oxides + mullite associated with Si-rich glass and hydrothermal quartz, which indicate the fundamental role played by hydrothermal fluid circulation in the xenopumice protolith. The petrological data agree with a pre-syneruptive formation of the xenopumice, when El Hierro basanite magma intruded hydrothermally altered trachyandesite to trachyte rocks and triggered local partial melting. Therefore, the El Hierro xenopumice represents a snapshot of the transient processes at the magma-wall rock interface, which normally occurs in the feeding system of active volcanoes.

  6. Geology, alteration, and magmatic-hydrothermal history of The Geysers felsite -- potential applications for exploration and development

    SciTech Connect

    Hulen, J.B.; Nielson, D.L. )

    1993-01-01

    The [open quotes]felsite[close quotes] is a shallow, young, granitic intrusive body centrally located within and beneath. The Geysers steam field. The field and the felsite are coaxial, and hydrothermal alteration effected by hot-water dominated geothermal systems antedating the modern steam reservoir shows systematic vertical zonation with respect to the pluton. The research summarized in this communication was undertaken both to clarify the role of the pluton in reservoir evolution, and to characterize critical felsite-specific controls on the fields's deep porosity and permeability. The felsite comprises at least three major intrusive phases. Two are high-silica granites probably older than 1.3 Ma. The third is granodiorite (1 Ma), temporally and chemically equivalent to overlying extrusive dacites of the Clear Lake volcanic field. All three intrusive phases are too old to be heat sources for the modern steam field, but probably were the heat engines for the prior liquid-dominant systems. Younger, deeper magmatic heat sources are strongly implied for the current vapor-dominated regime. Porosity in the felsite is provided by: (1) Extensively mineralized fractures and breccias, probably of both tectonic and high-temperature hydrothermal origin; and (2) miarolitic cavities in the upper levels of the pluton. The latter could be analogous to calcite-dissolution cavities in overlying metagraywacke -- they could serve as storage sites for the fields's liquid water reserves. Porosity in these fractures, breccias, and vugs in partially occluded by hydrothermal vein minerals deposited in prior hotwater-dominated systems --tourmaline, ferroaxinite, quartz, potassium feldspar, epidote, actinolite, prehnite, and many others. Such secondary mineralization conceptually could serve as an excellent exploration guide to potentially productive portions of the felsite beyond the field's present boundaries.

  7. Thermoelectrically-cooled quartz microbalance

    NASA Technical Reports Server (NTRS)

    Mckeown, D.

    1975-01-01

    Temperature of microbalance can be maintained at ambient temperature or held at some other desired temperature. Microbalance has tow-stage thermoelectric device that controls temperature of quartz crystal. Heat can be pumped to or from balance by Peltier effect.

  8. Genetic analysis of quartz from pegmatites of the Mama-Chuya mica belt based on distribuition of isomorphic impurities, Russia

    NASA Astrophysics Data System (ADS)

    Rakov, L. T.; Tkachev, A. V.; Sakhnov, A. A.

    2013-02-01

    The effect of the formation conditions of pegmatites in the Mama-Chuya mica belt on the distribution of isomorphic Al, Ti, and Ge impurities in quartz detected by electron paramagnetic resonance (EPR) has been estimated using the isogen method, which takes into account the relationship between this distribution and geological time. It has been revealed that each of the studied types of pegmatite veins is described by special isogens that reflect interrelations between concentrations of various isomorphic impurities. The typification of veins, enrichment of parental melt in water, and other factors affect the isogens. New potentialities of the isogen method for genetic analysis of quartz have been established.

  9. Natural fracking and the genesis of five-element veins

    NASA Astrophysics Data System (ADS)

    Markl, Gregor; Burisch, Mathias; Neumann, Udo

    2016-08-01

    Hydrothermal Ag-Co-Ni-Bi-As (five-element vein type) ore deposits show very conspicuous textures of the native elements silver, bismuth, and arsenic indicating formation from a rapid, far-from-equilibrium process. Such textures include up to dm-large tree- and wire-like aggregates overgrown by Co-Ni-Fe arsenides and mostly carbonates. Despite the historical and contemporary importance of five-element vein type deposits as sources of silver, bismuth, and cobalt, and despite of spectacular museum specimens, their process of formation is not yet understood and has been a matter of debate since centuries. We propose, based on observations from a number of classical European five-element vein deposits and carbon isotope analyses, that "natural fracking," i.e., liberation of hydrocarbons or hydrocarbon-bearing fluids during break up of rocks in the vicinity of an active hydrothermal system and mixing between these hydrocarbons (e.g., methane and/or methane-bearing fluids) and a metal-rich hydrothermal fluid is responsible for ore precipitation and the formation of the unusual ore textures and assemblages. Thermodynamic and isotope mixing calculations show that the textural, chemical, and isotopic features of the investigated deposits can entirely be explained by this mechanism.

  10. Natural fracking and the genesis of five-element veins

    NASA Astrophysics Data System (ADS)

    Markl, Gregor; Burisch, Mathias; Neumann, Udo

    2016-05-01

    Hydrothermal Ag-Co-Ni-Bi-As (five-element vein type) ore deposits show very conspicuous textures of the native elements silver, bismuth, and arsenic indicating formation from a rapid, far-from-equilibrium process. Such textures include up to dm-large tree- and wire-like aggregates overgrown by Co-Ni-Fe arsenides and mostly carbonates. Despite the historical and contemporary importance of five-element vein type deposits as sources of silver, bismuth, and cobalt, and despite of spectacular museum specimens, their process of formation is not yet understood and has been a matter of debate since centuries. We propose, based on observations from a number of classical European five-element vein deposits and carbon isotope analyses, that "natural fracking," i.e., liberation of hydrocarbons or hydrocarbon-bearing fluids during break up of rocks in the vicinity of an active hydrothermal system and mixing between these hydrocarbons (e.g., methane and/or methane-bearing fluids) and a metal-rich hydrothermal fluid is responsible for ore precipitation and the formation of the unusual ore textures and assemblages. Thermodynamic and isotope mixing calculations show that the textural, chemical, and isotopic features of the investigated deposits can entirely be explained by this mechanism.

  11. The physical hydrology of magmatic-hydrothermal systems: High-resolution 18O records of magmatic-meteoric water interaction from the Yankee Lode tin deposit (Mole Granite, Australia)

    NASA Astrophysics Data System (ADS)

    Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Heinrich, Christoph A.; Baumgartner, Lukas; Bouvier, Anne-Sophie

    2016-04-01

    Magmatic-hydrothermal ore deposits are important economic Cu, Au, Mo and Sn resources (Sillitoe, 2010, Kesler, 1994). The ore formation is a result of superimposed enrichment processes and metals can precipitate due to fluid-rock interaction and/or temperature drop caused by convection or mixing with meteoric fluid (Heinrich and Candela 2014). Microthermometry and LA-ICP MS trace element analyses of fluid inclusions of a well-characterized quartz sample from the Yankee Lode quartz-cassiterite vein deposit (Mole Granite, Australia) suggest that tin precipitation was driven by dilution of hot magmatic water by meteoric fluids (Audétat et al.1998). High resolution in situ oxygen isotope measurements of quartz have the potential to detect changing fluid sources during the evolution of a hydrothermal system. We analyzed the euhedral growth zones of this previously well-studied quartz sample. Growth temperatures are provided by Audétat et al. (1998) and Audétat (1999). Calculated δ 18O values of the quartz- and/or cassiterite-precipitating fluid show significant variability through the zoned crystal. The first and second quartz generations (Q1 and Q2) were precipitated from a fluid of magmatic isotopic composition with δ 18O values of ˜ 8 - 10 ‰. δ 18O values of Q3- and tourmaline-precipitating fluids show a transition from magmatic δ 18O values of ˜ 8 ‰ to ˜ -5 ‰. The outermost quartz-chlorite-muscovite zone was precipitated from a fluid with a significant meteoric water component reflected by very light δ 18O values of about -15 ‰ which is consistent with values found by previous studies (Sun and Eadington, 1987) using conventional O-isotope analysis of veins in the distal halo of the granite intrusion. Intense incursion of meteoric water during Q3 precipitation (light δ 18O values) agrees with the main ore formation event, though the first occurrence of cassiterite is linked to Q2 precipitating fluid with magmatic-like isotope signature. This

  12. Geochronology and Nd isotope geochemistry of the Gameleira Cu-Au deposit, Serra dos Carajás, Brazil: 1.8-1.7 Ga hydrothermal alteration and mineralization

    NASA Astrophysics Data System (ADS)

    Pimentel, Márcio M.; Lindenmayer, Zara G.; Laux, Jorge H.; Armstrong, Richard; de Araújo, Janice Caldas

    2003-01-01

    The Gameleira deposit is one of several important Cu-Au deposits associated with the late Archean (ca. 2.7 Ga) volcanic rocks of the Itacaiúnas supergroup in the Carajás mineral province, southeastern Pará. It comprises mainly biotite- and sulphide-rich veins and quartz-grunerite-biotite-gold hydrothermal veins that cut andesitic rocks. It is interpreted as representative of the Fe oxide Cu-Au class of deposit. Sm-Nd isotopic data indicate an age of 2719±80 Ma (MSWD=3.0) and ɛNd( T) of -1.4 for the host meta-andesites. Metavolcanic rocks and cogenetic gabbros give an age of 2757±81 Ma (1 σ) with ɛNd( T) of -0.8. This is considered the best estimate for the crystallization age of the Gameleira volcanic and subvolcanic rocks. Negative ɛNd( T) and Archean TDM model ages (mostly between 2.8 and 3.1 Ga) suggest some contamination with older crustal material. The andesitic/gabbroic rocks are cut by two generations of granite dykes. The older has striking petrographic and geochemical similarities to the ca. 1.87 Ga alkali-rich Pojuca granite, which is exposed a few kilometers to the northwest of the deposit. The younger is a leucogranite with a U-Pb SHRIMP age of 1583+9/-7 Ma. Neodymium isotopic analyses of the two generations of granites indicate a strong crustal affinity and possible derivation from reworking of the Archean crust. The quartz-grunerite-gold hydrothermal vein yields a Sm-Nd isochron (MSWD=.83) age of 1839±15 Ma (1 σ) with ɛNd( T) of -9.2. Pervasive potassic alteration, represented by the widespread formation of biotite in the country rocks, is dated by Ar-Ar at 1734±8 Ma, and a similar age of 1700±31 Ma (1 σ) is indicated by the Sm-Nd isochron for the biotite-sulphide veins. Similar to that for the quartz-grunerite vein, the ɛNd( T) value for the sulphide-rich veins is strongly negative (-8.2), thereby suggesting that the original fluids percolated through, leached, or were derived from igneous rocks with an Archaean Nd isotopic signature

  13. Distinguishing shocked from tectonically deformed quartz by the use of the SEM and chemical etching

    USGS Publications Warehouse

    Gratz, A.J.; Fisler, D.K.; Bohor, B.F.

    1996-01-01

    Multiple sets of crystallographically-oriented planar deformation features (PDFs) are generated by high-strain-rate shock waves at pressures of > 12 GPa in naturally shocked quartz samples. On surfaces, PDFs appear as narrow (50-500 nm) lamellae filled with amorphosed quartz (diaplectic glass) which can be etched with hydrofluoric acid or with hydrothermal alkaline solutions. In contrast, slow-strain-rate tectonic deformation pressure produces wider, semi-linear and widely spaced arrays of dislocation loops that are not glass filled. Etching samples with HF before examination in a scanning electron microscope (SEM) allows for unambiguous visual distinction between glass-filled PDFs and glass-free tectonic deformation arrays in quartz. This etching also reveals the internal 'pillaring' often characteristic of shock-induced PDFs. This technique is useful for easily distinguishing between shock and tectonic deformation in quartz, but does not replace optical techniques for characterizing the shock features.

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

    USGS Publications Warehouse

    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

  15. Long-lived interaction between hydrothermal and magmatic fluids in the Soultz-sous-Forêts granitic system (Rhine Graben, France)

    NASA Astrophysics Data System (ADS)

    Gardien, Véronique; Rabinowicz, Michel; Vigneresse, Jean-Louis; Dubois, Michel; Boulvais, Philippe; Martini, Rossana

    2016-03-01

    The 5 km deep drilling at Soultz-sous-Forêts samples a granitic intrusion under its sedimentary cover. Core samples at different depths allow study of the evolving conditions of fluid-rock interaction, from the syn-tectonic emplacement of Hercynian granites at depth until post-cooling history and alteration close to the surface. Hydrogen, carbon and oxygen isotope compositions of CO2 and H2O have been measured in fluid inclusions trapped in magmatic quartz within samples collected along the drill core. Early Fluid Inclusions Assemblage (FIA) contains aqueous carbonic fluids whereas the latest FIA are H2O-rich. In the early FIA, the amount of CO2 and the δ13C value both decrease with depth, revealing two distinct sources of carbon, one likely derived from sedimentary carbonates (δ13C = - 2‰ V-PDB) and another from the continental crust (δ13C = - 9‰ V-PDB). The carbon isotope composition of bulk granites indicates a third carbon source of organic derivation (δ13C = - 20‰ V-PDB). Using a δD - δ18O plot, we argue that the water trapped in quartz grains is mainly of meteoric origin somewhat mixed with magmatic water. The emplacement of the Soultz-sous-Forêts granite pluton occurred in a North 030-040° wrench zone. After consolidation of the granite mush at ~ 600 °C, sinistral shear (γ ~ 1) concentrated the final leucocratic melt in vertical planes oriented along (σ1, σ2). Crystallization of this residual leucocratic melt occurred while shearing was still active. At a temperature of ~ 550 °C, crystallization ended with the formation of vertical quartz veins spaced about 5 mm, and exhibiting a width of several cm. The quartz veins form a connected network of a few kilometers in height, generated during hydrothermal contraction of the intrusion. Quartz crystallization led to the exsolution of 30% by volume of the aqueous fluid. As quartz grains were the latest solid phase still plastic, shearing localized inside the connected quartz network. Aqueous

  16. Pelvic Vein Embolisation in the Management of Varicose Veins

    SciTech Connect

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

    2008-11-15

    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.

  17. Ovarian vein thrombosis

    PubMed Central

    Jenayah, Amel Achour; Saoudi, Sarra; Boudaya, Fethia; Bouriel, Ines; Sfar, Ezzeddine; Chelli, Dalenda

    2015-01-01

    Ovarian vein thrombosis (OVT) is a rare cause of abdominal pain that may mimic a surgical abdomen. It is most often diagnosed during the postpartum period. In this report, we present four cases of postoperative ovarian vein thrombosis. The complications of OVT can be significant, and the diagnosis relies on a careful examination of the radiographic findings. It can occur with lower quadrant abdominal pain, especially in the setting of recent pregnancy, abdominal surgery, pelvic inflammatory disease, or malignancy. Diagnosis can be made with confidence using ultrasound, computed tomography or magnetic resonance imaging. Treatment of ovarian vein thrombosis is particularly important in the post-partum patients, with anticoagulation therapy being the current recommendation. PMID:26526119

  18. Acquired Jugular Vein Aneurysm

    PubMed Central

    Hopsu, Erkki; Tarkkanen, Jussi; Vento, Seija I.; Pitkäranta, Anne

    2009-01-01

    Venous malformations of the jugular veins are rare findings. Aneurysms and phlebectasias are the lesions most often reported. We report on an adult patient with an abruptly appearing large tumorous mass on the left side of the neck identified as a jugular vein aneurysm. Upon clinical examination with ultrasound, a lateral neck cyst was primarily suspected. Surgery revealed a saccular aneurysm in intimate connection with the internal jugular vein. Histology showed an organized hematoma inside the aneurysmal sac, which had a focally thinned muscular layer. The terminology and the treatment guidelines of venous dilatation lesions are discussed. For phlebectasias, conservative treatment is usually recommended, whereas for saccular aneurysms, surgical resection is the treatment of choice. While an exact classification based on etiology and pathophysiology is not possible, a more uniform taxonomy would clarify the guidelines for different therapeutic modalities for venous dilatation lesions. PMID:20107571

  19. Dislocation creep of dry quartz

    NASA Astrophysics Data System (ADS)

    Kilian, Rüdiger; Heilbronner, Renée.; Holyoke, Caleb W.; Kronenberg, Andreas K.; Stünitz, Holger

    2016-05-01

    Small-scale shear zones within the Permian Truzzo meta-granite developed during the Alpine orogeny at amphibolite facies conditions. In these shear zones magmatic quartz deformed by dislocation creep and recrystallized dynamically by grain boundary migration with minor subgrain rotation recrystallization to a grain size of around 250-750 µm, consistent with flow at low differential stresses. Fourier transform infrared (FTIR) spectroscopy reveals very low water contents in the interior of recrystallized grains (in the form of discrete OH peaks, ~20 H/106Si and very little broad band absorption, <100 H/106Si). The spectral characteristics are comparable to those of dry Brazil quartz. In FTIR spectra, magmatic quartz grains show a broad absorption band related with high water concentrations only in those areas where fluid inclusions are present while other areas are dry. Drainage of fluid inclusions and synkinematic growth of hydrous minerals indicates that a hydrous fluid has been available during deformation. Loss of intragranular water during grain boundary migration recrystallization did not result in a microstructure indicative of hardening. These FTIR measurements provide the first evidence that quartz with extremely low intragranular water contents can deform in nature by dislocation creep at low differential stresses. Low intragranular water contents in naturally deformed quartz may not be necessarily indicative of a high strength, and the results are contrary to implications taken from deformation experiments where very high water contents are required to allow dislocation creep in quartz. It is suggested that dislocation creep of quartz in the Truzzo meta-granite is possible to occur at low differential stresses because sufficient amounts of intergranular water ensure a high recovery rate by grain boundary migration while the absence of significant amounts of intragranular water is not crucial at natural conditions.

  20. Varicose vein surgery.

    PubMed

    Kendler, Micheal; Fellmer, Peter T; Wetzig, Tino

    2012-03-01

    Venous diseases are common in the general population. After a comprehensive diagnostic evaluation, an individual therapeutic approach should be selected on the basis of the findings, with the aim of treating the diseased vein segments and improving quality of life. Numerous therapeutic options are available for the treatment of varicose veins. In addition to conservative methods such as compression therapy, exercise or drugs, surgical procedures such as traditional surgery, thermal ablation techniques or sclerotherapy can be performed. Recent developments include the use of endoluminal water vapor or mechano-chemical endovenous ablation. PMID:22222053

  1. Uranium-series age determination of calcite veins, VC-1 drill core, Valles Caldera, New Mexico

    NASA Astrophysics Data System (ADS)

    Sturchio, Neil C.; Binz, Carl M.

    1988-06-01

    Uranium-series analysis (238U-234U-230Th) of 13 calcite veins from the hydrothermally altered Madera Limestone in the VC-1 drill core was performed to determine the ages of the veins and their relation to the Valles hydrothermal system. Thermal water from VC-1 and two hot springs in San Diego Canyon was analyzed for U and (234U/238U) to help evaluate the constancy of initial (234U/238U). The (230Th/234U) age of one of the veins is ˜95 kyr, and those of two other veins are ˜230 and ˜250 kyr. Five of the veins have near equilibrium (230Th/234U) and are probably older than ˜0.3 m.y. Uranium concentrations in the remaining veins are too low for analysis by the α-spectrometry techniques employed in this study. Of the five veins near (230Th/234U) equilibrium, four are also near (234U/238U) equilibrium, suggesting ages greater than ˜1.0 m.y., but one has (234U/238U) = 1.15, suggesting an age between ˜0.3 and ˜1.0 m.y. Calculated initial (234U/238U) of the veins yielding relatively young ages are neither equal to each other nor to (234U/238U) in thermal water from VC-1, indicating inconstancy of initial (234U/238U) that may be related to variations in groundwater mixing proportions. Three of the four veins that yield relatively young ages consist of coarse, sparry, vuggy calcite, suggesting that this may be the type of calcite vein which forms under conditions resembling those encountered presently in VC-1. The analytical data are consistent with closed-system behavior of U and Th in the VC-1 calcite veins.

  2. Role of Substrate on Quartz Cementation in Quartz Aggregates

    NASA Astrophysics Data System (ADS)

    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

  3. Thermal Effects in the Hydrothermal Regime of Magmatic-Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Candela, P. A.

    2002-05-01

    Models of conductive and convective cooling of epizonal magma bodies commonly show temperatures in the country rock that are at or below 500 C. Indeed, simple conductive cooling models place the contact temperature below the midpoint of the intrusion and country rock temperatures, which for felsic magmas in cold country rock (cf. Furlong et al., 1991, Rev. in Min. v. 26), is approximately 500 C or lower. However, some vein systems record temperatures e.g. from fluid inclusions or phase equilibria that exceed 500 C. In some cases, as in some deep skarn deposits, high temperatures of ore deposition probably result from high country rock temperatures. Veins may also occur in the already cooled portions of an ore-generative pluton, which can be at any temperature below the solidus. In still other cases, high country rock temperatures may be heated by previous magmatic events (thermal ground preparation). However, high temperatures of mineral alteration or deposition may be produced in initially cold country rock by flux of high temperature magmatic volatile phase from the magma itself. This is a likely explanation when ore is associated with early stages of magmatism at shallow levels in the crust. The mass conservation equations of infiltration theory (cf. Ferry, 1991, Rev. in Min. v. 26), can be used to estimate time-integrated fluid fluxes, q, given changes in quartz solubility with temperature, geothermal and geobaric gradients in shallow magmatic environments, and order of magnitude vein quartz densities in porphyry copper deposits. The change in the silica content of the rock due to quartz veining is then given by: \\Delta cQZ =- \\int Jw dt \\times \

  4. 160 Ma of magmatic/hydrothermal and metamorphic activity in the Gällivare area: Re-Os dating of molybdenite and U-Pb dating of titanite from the Aitik Cu-Au-Ag deposit, northern Sweden

    NASA Astrophysics Data System (ADS)

    Wanhainen, Christina; Billström, Kjell; Martinsson, Olof; Stein, Holly; Nordin, Roger

    2005-12-01

    Host rocks to the Aitik Cu-Au-Ag deposit in northern Sweden are strongly altered and deformed Early Proterozoic mica(-amphibole) schists and gneisses. The deposit is characterised by numerous mineralisation styles, vein and alteration types. Four samples were selected for Re-Os molybdenite dating and 12 samples for U-Pb titanite dating in order to elucidate the magmatic/hydrothermal and metamorphic history following primary ore deposition in the Aitik Cu-Au-Ag deposit. Samples represent dyke, vein and alteration assemblages from the ore zone, hanging wall and footwall to the deposit. Re-Os dating of molybdenite from deformed barite and quartz veins yielded ages of 1,876±10 Ma and 1,848±8 Ma, respectively. A deformed pegmatite dyke yielded a Re-Os age of 1,848±6 Ma, and an undeformed pegmatite dyke an age of 1,728±7 Ma. U-Pb dating of titanite from a diversity of alteration mineral associations defines a range in ages between 1,750 and 1,805 Ma with a peak at ca. 1,780 Ma. The ages obtained, together with previous data, bracket a 160-Ma (1,890-1,730 Ma) time span encompassing several generations of magmatism, prograde to peak metamorphism, and post-peak cooling; events resulting in the redistribution and addition of metals to the deposit. This multi-stage evolution of the Aitik ore body suggests that the deposit was affected by several thermal events that ultimately produced a complex ore body. The Re-Os and U-Pb ages correlate well with published regional Re-Os and U-Pb age clusters, which have been tied to major magmatic, hydrothermal, and metamorphic events. Primary ore deposition at ca. 1,890 Ma in connection with intrusion of Haparanda granitoids was followed by at least four subsequent episodes of metamorphism and magmatism. Early metamorphism at 1,888-1,872 Ma overlapping with Haparanda (1,890-1,880 Ma) and Perthite-monzonite (1,880-1,870 Ma) magmatism clearly affected the Aitik area, as well as late metamorphism and Lina magmatism at 1,810-1,774 Ma and

  5. Portal vein thrombosis.

    PubMed

    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. PMID:25941431

  6. Portal Vein Thrombosis

    PubMed Central

    Chawla, Yogesh K.; Bodh, Vijay

    2015-01-01

    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. PMID:25941431

  7. Elastomechanical properties of bovine veins.

    PubMed

    Rossmann, Jenn Stroud

    2010-02-01

    Veins have historically been discussed in qualitative, relative terms: "more compliant" than arteries, subject to "lower pressures". The structural and compositional differences between arteries and veins are directly related to the different functions of these vessels. Veins are often used as grafts to reroute flow from atherosclerotic arteries, and venous elasticity plays a role in the development of conditions such as varicose veins and valvular insufficiency. It is therefore of clinical interest to determine the elastomechanical properties of veins. In the current study, both tensile and vibration testing are used to obtain elastic moduli of bovine veins. Representative stress-strain data are shown, and the mechanical and failure properties reported. Nonlinear and viscoelastic behavior is observed, though most properties show little strain rate dependence. These data suggest parameters for constitutive modeling of veins and may inform the design and testing of prosthetic venous valves as well as vein grafts. PMID:20129420

  8. Living with Deep Vein Thrombosis

    MedlinePlus

    ... page from the NHLBI on Twitter. Living With Deep Vein Thrombosis NHLBI Resources Pulmonary Embolism (Health Topics) Non-NHLBI Resources Deep Vein Thrombosis (MedlinePlus) Pulmonary Embolism (MedlinePlus) Clinical Trials ...

  9. Petrography, sulfide mineral chemistry, and sulfur isotope evidence for a hydrothermal imprint on Musina copper deposits, Limpopo Province, South Africa: Evidence for a breccia pipe origin?

    NASA Astrophysics Data System (ADS)

    Chaumba, Jeff B.; Mundalamo, Humbulani R.; Ogola, Jason S.; Cox, J. A.; Fleisher, C. J.

    2016-08-01

    The Musina copper deposits are located in the Central Zone of the Limpopo orogenic belt in Limpopo Province, South Africa. We carried out a petrographic, sulfide composition, and δ34S study on samples from Artonvilla and Campbell copper deposits and a country rock granitic gneiss to Artonvilla Mine to place some constrains on the origin of these deposits. The assemblages at both Artonvilla and Campbell Mines of brecciated quartz, potassium feldspar, muscovite, chlorite, calcite, and amphibole are consistent with sericitic alteration. Quartz, amphibole, feldspars, and micas often display angular textures which are consistent with breccias. Sulfur concentrations in pyrite from Artonvilla Mine plot in a narrow range, from 50.2 wt. % to 55.7 wt. %. With the exception of a positive correlation between Fe and Cu, no well defined correlations are shown by data from the Musina copper deposits. The occurrence of sulfides both as inclusions in, or as interstitial phases in silicates, suggests that hydrothermal alteration that affected these deposits most likely helped concentrate the mineralization at the Musina copper deposits. Sulfur concentrations in chalcopyrite samples investigated vary widely whereas the copper concentrations in chalcopyrite are not unusually higher compared to those from chalcopyrite from other tectonic settings, probably indicating that either the Cu in the Musina copper deposits occurs in native form, and/or that it is hosted by other phases. This observation lends support to the Cu having been concentrated during a later hydrothermal event. One sample from Artonvilla Mine (AtCal01) yielded pyrite δ34S values of 3.1and 3.6‰ and chalcopyrite from the same sample yielded a value of 3.9‰. A country rock granitic gneiss to Artonvilla Mine yielded a δ34Spyrite value of 8.2‰. For Campbell Mine samples, one quartz vein sample has a δ34Spyrite value of 0.5‰ whereas chalcopyrite samples drilled from different areas within the same sample

  10. Halogens and noble gases in Mathematician Ridge meta-gabbros, NE Pacific: implications for oceanic hydrothermal root zones and global volatile cycles

    NASA Astrophysics Data System (ADS)

    Kendrick, Mark A.; Honda, Masahiko; Vanko, David A.

    2015-12-01

    Six variably amphibolitised meta-gabbros cut by quartz-epidote veins containing high-salinity brine, and vapour fluid inclusions were investigated for halogen (Cl, Br, I) and noble gas (He, Ne, Ar, Kr, Xe) concentrations. The primary aims were to investigate fluid sources and interactions in hydrothermal root zones and determine the concentrations and behaviours of these elements in altered oceanic crust, which is poorly known, but has important implications for global volatile (re)cycling. Amphiboles in each sample have average concentrations of 0.1-0.5 wt% Cl, 0.5-3 ppm Br and 5-68 ppb I. Amphibole has Br/Cl of ~0.0004 that is about ten times lower than coexisting fluid inclusions and seawater, and I/Cl of 2-44 × 10-6 that is 3-5 times lower than coexisting fluid inclusions but higher than seawater. The amphibole and fluid compositions are attributed to mixing halogens introduced by seawater with a large halogen component remobilised from mafic lithologies in the crust and fractionation of halogens between fluids and metamorphic amphibole formed at low water-rock ratios. The metamorphic amphibole and hydrothermal quartz are dominated by seawater-derived atmospheric Ne, Ar, Kr and Xe and mantle-derived He, with 3He/4He of ~9 R/Ra (Ra = atmospheric ratio). The amphibole and quartz preserve high 4He concentrations that are similar to MORB glasses and have noble gas abundance ratios with high 4He/36Ar and 22Ne/36Ar that are greater than seawater and air. These characteristics result from the high solubility of light noble gases in amphibole and suggest that all the noble gases can behave similarly to `excess 40Ar' in metamorphic hydrothermal root zones. All noble gases are therefore trapped in hydrous minerals to some extent and can be inefficiently lost during metamorphism implying that even the lightest noble gases (He and Ne) can potentially be subducted into the Earth's mantle.

  11. Low-temperature intracrystalline deformation microstructures in quartz

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    A review of numerous genetic interpretations of the individual low-temperature intracrystalline deformation microstructures in quartz shows that there is no consensus concerning their formation mechanisms. Therefore, we introduce a new, purely descriptive terminology for the three categories of intracrystalline deformation microstructures formed in the low-quartz stability field: fine extinction bands (FEB), wide extinction bands (WEB) and localised extinction bands (LEB). The localised extinction bands are further subdivided into blocky (bLEB), straight (sLEB) and granular (gLEB) morphological types. A detailed polarised light microscopy study of vein-quartz from the low-grade metamorphic High-Ardenne slate belt (Belgium) further reveals a series of particular geometric relationships between these newly defined intracrystalline deformation microstructures. These geometric relationships are largely unrecognised or underemphasised in the literature and need to be taken into account in any future genetic interpretation. Based on our observations and a critical assessment of the current genetic models, we argue that the interpretation of the pertinent microstructures in terms of ambient conditions and deformation history should be made with care, as long as the genesis of these microstructures is not better confined.

  12. Hydrothermal alteration and Cu–Ni–PGE mobilization in the charnockitic rocks of the footwall of the South Kawishiwi intrusion, Duluth Complex, USA

    PubMed Central

    Benkó, Zsolt; Mogessie, Aberra; Molnár, Ferenc; Krenn, Kurt; Poulson, Simon R.; Hauck, Steven; Severson, Mark; Arehart, Greg B.

    2015-01-01

    In the Neoarchean (~ 2.7 Ga) contact metamorphosed charnockitic footwall of the Mesoproterosoic (1.1 Ga) South Kawishiwi intrusion of the Duluth Complex, the primary metamorphic mineral assemblage and Cu–Ni–PGE sulfide mineralization is overprinted by an actinolite + chlorite + cummingtonite + prehnite + pumpellyite + quartz + calcite hydrothermal mineral assemblage along 2–3 cm thick veins. In calcite, hosted by the hydrothermal alteration zones and in a single recrystallized quartz porphyroblast, four different fluid inclusion assemblages are documented; the composition of these fluid inclusions provide p–T conditions of the fluid flow, and helps to define the origin of the fluids and evaluate their role in the remobilization and reprecipitation of the primary metamorphic sulfide assemblage. Pure CO2 fluid inclusions were found as early inclusions in recrystallized quartz porphyroblast. These inclusions may have been trapped during the recrystallization of the quartz during the contact metamorphism of the footwall charnockite in the footwall of the SKI. The estimated trapping pressure (1.6–2.0 kbar) and temperature (810–920 °C) conditions correspond to estimates based on felsic veins in the basal zones of the South Kawishiwi intrusion. Fluid inclusion assemblages with CO2–H2O–NaCl and CH4–N2–H2O–NaCl compositions found in this study along healed microfractures in the recrystallized quartz porphyroblast establish the heterogeneous state of the fluids during entrapment. The estimated trapping pressure and temperature conditions (240–650 bar and 120–150 °C for CO2–H2O–NaCl inclusions and 315–360 bar and 145–165 °C for CH4–N2–H2O–NaCl inclusions) are significantly lower than the p–T conditions (> 700 °C and 1.6–2 kbar) during the contact metamorphism, indicating that this fluid flow might not be related to the cooling of the Duluth Complex and its contact aureole. The presence of chalcopyrite

  13. The chemistry of hydrothermal magnetite: a review

    USGS Publications Warehouse

    Nadoll, Patrick; Angerer, Thomas; Mauk, Jeffrey L.; French, David; Walshe, John

    2014-01-01

    Magnetite (Fe3O4) is a well-recognized petrogenetic indicator and is a common accessory mineral in many ore deposits and their host rocks. Recent years have seen an increased interest in the use of hydrothermal magnetite for provenance studies and as a pathfinder for mineral exploration. A number of studies have investigated how specific formation conditions are reflected in the composition of the respective magnetite. Two fundamental questions underlie these efforts — (i) How can the composition of igneous and, more importantly, hydrothermal magnetite be used to discriminate mineralized areas from barren host rocks, and (ii) how can this assist exploration geologists to target ore deposits at greater and greater distances from the main mineralization? Similar to igneous magnetite, the most important factors that govern compositional variations in hydrothermal magnetite are (A) temperature, (B) fluid composition — element availability, (C) oxygen and sulfur fugacity, (D) silicate and sulfide activity, (E) host rock buffering, (F) re-equilibration processes, and (G) intrinsic crystallographic controls such as ionic radius and charge balance. We discuss how specific formation conditions are reflected in the composition of magnetite and review studies that investigate the chemistry of hydrothermal and igneous magnetite from various mineral deposits and their host rocks. Furthermore, we discuss the redox-related alteration of magnetite (martitization and mushketovitization) and mineral inclusions in magnetite and their effect on chemical analyses. Our database includes published and previously unpublished magnetite minor and trace element data for magnetite from (1) banded iron formations (BIF) and related high-grade iron ore deposits in Western Australia, India, and Brazil, (2) Ag–Pb–Zn veins of the Coeur d'Alene district, United States, (3) porphyry Cu–(Au)–(Mo) deposits and associated (4) calcic and magnesian skarn deposits in the southwestern United

  14. Laser welding of fused quartz

    DOEpatents

    Piltch, Martin S.; Carpenter, Robert W.; Archer, III, McIlwaine

    2003-06-10

    Refractory materials, such as fused quartz plates and rods are welded using a heat source, such as a high power continuous wave carbon dioxide laser. The radiation is optimized through a process of varying the power, the focus, and the feed rates of the laser such that full penetration welds may be accomplished. The process of optimization varies the characteristic wavelengths of the laser until the radiation is almost completely absorbed by the refractory material, thereby leading to a very rapid heating of the material to the melting point. This optimization naturally occurs when a carbon dioxide laser is used to weld quartz. As such this method of quartz welding creates a minimum sized heat-affected zone. Furthermore, the welding apparatus and process requires a ventilation system to carry away the silicon oxides that are produced during the welding process to avoid the deposition of the silicon oxides on the surface of the quartz plates or the contamination of the welds with the silicon oxides.

  15. Spontaneous Iliac Vein Rupture

    PubMed Central

    Kim, Dae Hwan; Park, Hyung Sub; Lee, Taeseung

    2015-01-01

    Spontaneous iliac vein rupture (SIVR) is a rare entity, which usually occurs without a precipitating factor, but can be a life-threatening emergency often requiring an emergency operation. This is a case report of SIVR in a 62-year-old female who presented to the emergency room with left leg swelling. Workup with contrast-enhanced computed tomography revealed a left leg deep vein thrombosis with May-Thurner syndrome and a hematoma in the pelvic cavity without definite evidence of arterial bleeding. She was managed conservatively without surgical intervention, and also underwent inferior vena cava filter insertion and subsequent anticoagulation therapy for pulmonary thromboembolism. This case shows that SIVR can be successfully managed with close monitoring and conservative management, and anticoagulation may be safely applied despite the patient presenting with venous bleeding. PMID:26217647

  16. Cierco Pb-Zn-Ag vein deposits: Isotopic and fluid inclusion evidence for formation during the mesozoic extension in the pyrenees of Spain

    USGS Publications Warehouse

    Johnson, C.A.; Cardellach, E.; Tritlla, J.; Hanan, B.B.

    1996-01-01

    The Cierco Pb-Zn-Ag vein deposits, located in the central Pyrenees of Spain, crosscut Paleozoic metasedimentary rocks and are in close proximity to Hercynian granodiorite dikes and plutons. Galena and sphalerite in the deposits have average ??34S values of -4.3 and -0.8 per mil (CDT), respectively. Coexisting mineral pairs give an isotopic equilibration temperature range of 89?? to 163??C which overlaps with the 112?? to 198??C range obtained from primary fluid inclusions. Coexisting quartz has a ??18O value of 19 ?? 1 per mil (VSMOW). The fluid which deposited these minerals is inferred to have had ??18OH2o and ??34SH2s values of 5 ?? 1 and -1 ?? 1 per mil, respectively. Chemical and microthermometric analyses of fluid inclusions in quartz and sphalerite indicate salinities of 3 to 29 wt percent NaCl equiv with Na+ and Ca2+ as the dominant cations in solution. The Br/Cl and I/Cl ratios differ from those characteristic of magmatic waters and pristine seawater, but show some similarity to those observed in deep ground waters in crystalline terranes, basinal brines, and evaporated seawater, Barite, which postdates the sulfides, spans isotopic ranges of 13 to 21 per mil, 10 to 15 per mil, and 0.7109 to 0.7123 for ??34S, ??18O, and 87Sr/86Sr, respectively. The three parameters are correlated providing strong evidence that the barites are products of fluid mixing. We propose that the Cierco deposits formed along an extensional fault system at the margin of a marine basin during the breakup of Pangea at some time between the Early Triassic and Early Cretaceous. Sulfide deposition corresponded to an upwelling of hydrothermal fluid from the Paleozoic basement and was limited by the amount of metals carried by the fluid. Barite deposition corresponded to the waning of upward flow and the collapse of sulfate-rich surface waters onto the retreating hydrothermal plume. Calcite precipitated late in the paragenesis as meteoric or marine waters descended into the fault system

  17. Rear polymineral zone of near-veined metasomatic aureole in mesothermal Zun-Holba gold deposit (Eastern Sayan)

    NASA Astrophysics Data System (ADS)

    Cherkasova, T.; Kucherenko, I.; Abramova, R.

    2015-11-01

    Unique data of the mineralogical and petrochemical zoning of near- veined metasomatic aureole of mesothermal Zun-Holba gold deposit are presented and discussed. It was established that mineralogical and petrochemical zoning order is based on Korzhinsky theory describing the differential component mobility. However, the internal polymineral zone structure of metasomatic column in Zun-Holba deposit does not comply with Korzhinsky concept describing the mono-mineral composition of axial (ore-bearing quartz veins) and binary-mineral rear (quartz-sericite) zones. Mineral zoning complication is governed by component diffusion (from fractured fluid to pores) and pulsation mode of metalliferous fluid input into the mineralization area.

  18. Lithium isotope traces magmatic fluid in a seafloor hydrothermal system

    PubMed Central

    Yang, Dan; Hou, Zengqian; Zhao, Yue; Hou, Kejun; Yang, Zhiming; Tian, Shihong; Fu, Qiang

    2015-01-01

    Lithium isotopic compositions of fluid inclusions and hosted gangue quartz from a giant volcanogenic massive sulfide deposit in China provide robust evidence for inputting of magmatic fluids into a Triassic submarine hydrothermal system. The δ7Li results vary from +4.5‰ to +13.8‰ for fluid inclusions and from +6.7‰ to +21.0‰ for the hosted gangue quartz(9 gangue quartz samples containing primary fluid inclusions). These data confirm the temperature-dependent Li isotopic fractionation between hydrothermal quartz and fluid (i.e., Δδ7Liquartz-fluid = –8.9382 × (1000/T) + 22.22(R2 = 0.98; 175 °C–340 °C)), which suggests that the fluid inclusions are in equilibrium with their hosted quartz, thus allowing to determine the composition of the fluids by using δ7Liquartz data. Accordingly, we estimate that the ore-forming fluids have a δ7Li range from −0.7‰ to +18.4‰ at temperatures of 175–340 °C. This δ7Li range, together with Li–O modeling , suggest that magmatic fluid played a significant role in the ore formation. This study demonstrates that Li isotope can be effectively used to trace magmatic fluids in a seafloor hydrothermal system and has the potential to monitor fluid mixing and ore-forming process. PMID:26347051

  19. Visualizing trace element distribution in quartz using cathodoluminescence, electron microprobe, and laser ablation-inductively coupled plasma-mass spectrometry

    USGS Publications Warehouse

    Rusk, Brian; Koenig, Alan; Lowers, Heather

    2011-01-01

    Cathodoluminescent (CL) textures in quartz reveal successive histories of the physical and chemical fluctuations that accompany crystal growth. Such CL textures reflect trace element concentration variations that can be mapped by electron microprobe or laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Trace element maps in hydrothermal quartz from four different ore deposit types (Carlin-type Au, epithermal Ag, porphyry-Cu, and MVT Pb-Zn) reveal correlations among trace elements and between trace element concentrations and CL textures. The distributions of trace elements reflect variations in the physical and chemical conditions of quartz precipitation. These maps show that Al is the most abundant trace element in hydrothermal quartz. In crystals grown at temperatures below 300 °C, Al concentrations may vary by up to two orders of magnitude between adjacent growth zones, with no evidence for diffusion. The monovalent cations Li, Na, and K, where detectable, always correlate with Al, with Li being the most abundant of the three. In most samples, Al is more abundant than the combined total of the monovalent cations; however, in the MVT sample, molar Al/Li ratios are ~0.8. Antimony is present in concentrations up to ~120 ppm in epithermal quartz (~200–300 °C), but is not detectable in MVT, Carlin, or porphyry-Cu quartz. Concentrations of Sb do not correlate consistently with those of other trace elements or with CL textures. Titanium is only abundant enough to be mapped in quartz from porphyry-type ore deposits that precipitate at temperatures above ~400 °C. In such quartz, Ti concentration correlates positively with CL intensity, suggesting a causative relationship. In contrast, in quartz from other deposit types, there is no consistent correlation between concentrations of any trace element and CL intensity fluctuations.

  20. Quartz microfabrics in ultrahigh-pressure metamorphic rocks as indicators of low stress during uplift

    NASA Astrophysics Data System (ADS)

    Stäb, C.; Kruhl, J. H.; Trepmann, C.; Wang, L.

    2012-12-01

    Ultrahigh-pressure (UHP) metamorphic rocks form in convergent tectonic settings at depths > 90 km. In general, UHP conditions are defined by the stability of coesite. Coesite inclusions in various host minerals are a common feature in UHP rocks. We present data of typical quartz microfabrics, which resulted from the transformation of coesite to quartz in inclusions and intergranular regions, and evidence of high temperature quartz microfabrics. Jadeite-quartzites and eclogites from the Dabie Shan - Sulu orogenic belt (central China) were investigated, both of which experienced peak UHP conditions of ~ 660°C / > 2.6 GPa (Liou et al., 1997) and 700-800°C / 3.1-4.1 GPa (Yoshida et al., 2004), respectively, at c. 220-230 Ma due to a N-subduction of the Yangtze craton beneath the Sino-Korean craton, followed by a nearly isothermal decompression to ~ 1 GPa. Both rocks contain coesite and/or quartz inclusions (up to 350 μm in diameter) in clinopyroxene and garnet and in their symplectitic rims with various microstructures: (i) rims of palisade quartz commonly in contact to coesite, (ii) quartz aggregates with sutured grain boundaries and central remnants of coesite, (iii) larger central quartz grains with subgrains, (iv) foam quartz (c. 50 μm sized), and (v) apparently strain-free single quartz crystals. The foam quartz shows a random c-axis distribution but preferred crystallographic orientations of grain boundaries. Intergranular foam quartz is found in quartz-eclogites from the Sulu region, most probably indicating quartz-coesite transformation and, therefore, former UHP conditions. The preservation of foam quartz in intergranular regions and inclusions (especially in symplectites) indicates low stress and nearly no deformation during uplift in the stability field of quartz. This points to strain localization in shear zones (Zhao et al., 2003). In veins in the jadeite-quartzites and quartz-eclogites quartz occurs in larger aggregates with sutured grain boundaries

  1. Chemical, mineralogical, and mass-change examinations across a gold bearing vein zone in the Akoluk area, Ordu, NE Turkey

    NASA Astrophysics Data System (ADS)

    Yaylalı-Abanuz, Gülten; Tüysüz, Necati

    2010-05-01

    Chemical changes associated with gold mineralization in the Akoluk field in the western part of the eastern Pontides are investigated. The eastern Black Sea region hosts several Kuroko-type, massive sulfide deposits and, therefore, has drawn the attention of numerous workers. Acidic intrusions play an important role and structurally controlled zones of alteration are widespread thus leading to a great potential for epithermal gold deposits in this region. Rocks in the study area are part a volcano-sedimentary sequence. Vein-type mineralization occurs along fault systems in dacitic tuffs of upper Cretaceous age. These rocks are cut by a N45-50oE trending fault system, which is partly truncated by another N55-60oW extending fault system. Mineralization is observed in areas where these fault systems intersect. Native gold, zinckenite, stibnite, orpiment, realgar, cinnabar, pyrite, marcasite, sphalerite, and galena are the main ore minerals. Gangue minerals are quartz, barite and dolomite. Mineralization occurs as a replacement type in the wall rock, and filling type in fracture zones where voids are filled mostly by realgar, orpiment, zincenite, stibnite, quartz, barite, and sericite. The presence of framboidal and colloidal ore minerals and textures indicate that mineralization occur at low temperatures in an epithermal system. Zonal alteration is observed along the fault systems. Outward from the fault alteration types change from silicification through illitization, smectization to carbonatization. As a result of alteration, wall rock has undergone a total mass loss of 2.19%. Almost all the major oxide contents decreased to certain levels. Due to alteration of feldspar and hornblende, the concentrations of Na, Ca and Fe significantly decreased while silica and ore-forming elements were added to the host rocks. Development of carbonate minerals at the fringe of the fracture zone in the host rock indicates relatively alkaline conditions for the hydrothermal fluids in

  2. Triboluminescence of glasses and quartz

    NASA Astrophysics Data System (ADS)

    Chapman, G. N.; Walton, Alan J.

    1983-10-01

    The triboluminescent spectra of a variety of glasses and of crystalline quartz were measured while specimens were cut with a rotating diamond-impregnated saw blade. The spectra, which resemble the emission of a blackbody radiator, were recorded using an image-intensifier spectrograph. The data were intensity-corrected before being fitted to blackbody emission curves. Emission temperatures of around 1850 K for armor plate glass, 2100 K for Pyrex glass, 2400 K for soda lime glass, 2300 K for high-density lead glass, and 2800 K for cut quartz were obtained. It was found that the blackbody temperatures could be accounted for by a model in which a rectangular-shaped high-temperature zone, uniformly heated by energy released by plastic deformation near the crack tip, is supposed to propagate with the crack velocity [R. Weichert and K. Schonert, Q. J. Mech. Appl. Math. 31, 363-379 (1978)]. The measured blackbody temperatures imply zone widths of around 1×10-9 m. The spectrum from impact-fractured quartz was also measured; it was found to have a photoluminescent origin.

  3. [Coronary veins and coronary sinus tributary veins in Africans].

    PubMed

    Yangni-Angate, H; Kokoua, A; Kouassi, R; Kassanyou, S; Gnagne, Y; Guessan, G N; Cowppli-Bony, P; Memel, J B

    1995-01-01

    This anatomical study carried out on 40 African adults hearts studied branches of the coronary sinus. By using of injection of the coronary arteries and corrosion of the myocardium, the study identified certain peculiarities of the small coronary vein and the posterior descending interventricular vein in Africans. PMID:8519704

  4. Oxygen and Hydrogen Isotope Values for Unaltered and Hydrothermally Altered Samples from the Cretaceous Linga Plutonic Complex of the Peruvian Coastal Batholith near Ica.

    NASA Astrophysics Data System (ADS)

    Gonzalez, L. U.; Holk, G. J.; Clausen, B. L.; Poma Porras, O. A.

    2015-12-01

    A portion of the Peruvian Coastal Batholith near Ica, Peru is being studied using stable isotopes to determine the source of hydrothermal fluids that caused propylitic, phyllic, and potassic alteration in the mineralized Linga plutonic complex. Sources of hydrothermal fluids and water/rock ratios are estimated to understand the role of such fluids in alteration during cooling. A set of 64 mineral analysis from 18 igneous samples, 7 unaltered and 11 altered, were analyzed for D/H and 18O/16O isotopes. The δ18O values for whole rocks with no apparent alteration vary from +6.8‰ to +7.9‰, with sets of δ18O mineral values indicating isotopic equilibrium at closure temperatures from 571°C to 651°C, and no interaction with meteoric water. This conclusion is bolstered by hornblende (-87‰ to -64‰) and biotite (-81‰ to -74‰) δD values Most δ18O values for samples with hydrothermal alteration suggest that alteration results from magmatic fluids; however, several analyses indicate interaction with other fluids. The high δ18O values for plagioclase (+9.3‰) and hornblende (+6.3‰) from a metamorphic aureole in volcanic host rock near a plutonic intrusion may be due to interaction with metamorphic or low temperature magmatic fluids. Plagioclase (+2.6‰) and biotite (+0.1‰) δ18O values in a sample from the Jurassic volcanic envelope indicate a significant effect from meteoric-hydrothermal fluids. An altered monzonite yielded δ18O values for quartz (+5.5‰), K-spar (+5.6‰), and magnetite (+0.4‰), also suggesting interaction with meteoric fluids. A diorite from an area with strong epidotization produced an epidote δD value of -25.8‰ and a monzonite from a highly veined area has an epidote δD value of -36.1‰ suggesting interaction with sea water. This new data indicate that the Linga complex was primarily influenced by magmatic hydrothermal fluids, but metamorphic, meteoric, and sea water may have had some influence in producing alteration

  5. Doubly rotated contoured quartz resonators.

    PubMed

    Sinha, B K

    2001-09-01

    Doubly rotated contoured quartz resonators are used in the design of temperature-compensated stable clocks and dual-mode sensors for simultaneous measurements of pressure and temperature. The design of these devices is facilitated by models that can predict frequency spectra associated with the three thickness modes and temperature and stress-induced frequency changes as a function of crystalline orientation. The Stevens-Tiersten technique for the analysis of the C-mode of a doubly rotated contoured quartz resonator is extended to include the other two thickness modes. Computational results for harmonic and anharmonic overtones of all three thickness modes of such resonators help in optimizing the radius of curvature of the contour and electrode shape for suppression of unwanted modes and prevention of activity dips. The temperature and stress-induced changes in thickness-mode resonator frequencies are calculated from a perturbation technique for small dynamic fields superposed on a static bias. The static bias refers to either a temperature or stress-induced static deformation of the resonator plate. Phenomenological models are also used for calculating the temperature and stress-induced changes in resonant frequencies as a function of crystalline orientation. Results for the SBTC-cut quartz plate with a spherical convex contour of 260 mm indicate that normal trapping occurs for the third (n = 3) and fifth (n = 5) harmonic of the A-mode, the fundamental (n = 1) and third (n = 3) harmonic of the B-mode, and the fundamental (n = 1) and fifth (n = 5) harmonic of the C-mode. PMID:11570746

  6. Infrared imaging of varicose veins

    NASA Astrophysics Data System (ADS)

    Noordmans, Herke Jan; de Zeeuw, Raymond; Verdaasdonk, Ruud M.; Wittens, Cees H. A.

    2004-06-01

    It has been established that varicose veins are better visualized with infrared photography. As near-infrared films are nowadays hard to get and to develop in the digital world, we investigated the use of digital photography of varicose veins. Topics that are discussed are illumination setup, photography and digital image enhancement and analysis.

  7. Hydrothermal solidification of municipal solid waste incineration bottom ash with slag addition.

    PubMed

    Jing, Zhenzi; Ran, Xianqiang; Jin, Fangming; Ishida, Emile H

    2010-01-01

    Hydrothermal solidification of municipal solid waste incineration (MSWI) bottom ash has been carried out under saturated steam pressure (1.56 MPa) at 200 degrees C for up to 24 h by mixing quartz, slaked lime and water-cooled blast furnace slag (WBFS). The strength enhancement for the WBFS addition was best. The strength development was shown to be due mainly to tobermorite formation, and the tobermorite formation densified matrix, thus promoting the strength development. WBFS seemed to have a higher reactivity than the quartz during the initial hydrothermal process, which provided more silica available to harden the solidified specimens. However, a longer curing time (24 h) was favorable to the quartz dissolution for tobermorite formation, which in turn, enhanced the strength for quartz addition. Curing time affected the crystal morphology evolution, and the stubby plate of tobermorite seemed to result in a high strength enhancement in this study. Laboratory leaching tests were conducted to determine the amount of heavy metals dissolved from the final solidified specimens, and the leaching results showed that after hydrothermal processing the heavy metals dissolved from the solidified specimens were reduced effectively. As such, the hydrothermal processing may have a high potential for recycling/reusing MSWI ash on a large scale. PMID:20385479

  8. The economics of vein disease.

    PubMed

    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. PMID:17911565

  9. The Management of Varicose Veins

    PubMed Central

    Lin, Fan; Zhang, Shiyi; Sun, Yan; Ren, Shiyan; Liu, Peng

    2015-01-01

    This study aimed to review the current management modalities for varicose veins. There are a variety of management modalities for varicose veins. The outcomes of the treatment of varicose veins are different. The papers on the management of varicose veins were reviewed and the postoperative complications and efficacy were compared. Foam sclerotherapy and radiofrequency ablation were associated with less pain and faster recovery than endovenous laser ablation and surgical stripping. Patients undergoing endovenous laser ablation and radiofrequency ablation are most likely to have a faster recovery time and earlier return to work in comparison with those undergoing conventional high ligation and stripping. A randomized controlled study in multiple centers is warranted to verify which approach is better than others for the treatment of varicose veins. PMID:25594661

  10. Laser ablation MC-ICP-MS U/Pb geochronology of ocean basement calcium carbonate veins

    NASA Astrophysics Data System (ADS)

    Harris, M.; Coggon, R. M.; Teagle, D. A. H.; Roberts, N. M. W.; Parrish, R. R.

    2014-12-01

    Given the vast areas of mid ocean ridge flanks, even small chemical changes dues to fluid-rock interaction on the flanks may significantly influence global geochemical cycles. A conductive heat flow anomaly associated with hydrothermal circulation in ocean crust exists until on average 65Ma, but it is not known whether the thermal signature is accompanied by continued fluid-rock chemical exchange. Constraining the duration of fluid-rock chemical exchange is critical for calculating robust chemical fluxes associated with ridge flank hydrothermal circulation. Calcium carbonate veins form during relatively late-stage hydrothermal alteration and can be used to estimate the duration of ridge flank hydrothermal circulation. LA-MC-ICP-MS U/Pb geochronology provides a novel and independent approach to date calcium carbonate veins, and is advantageous over using the seawater Sr isotope curve that is in part non-unique and requires assumptions about the contribution of MORB Sr from fluid-rock exchange. LA-MC-ICP-MS U/Pb analyses have been undertaken on a suite of calcium carbonate veins from a range of basement ages (1.6 - 170 Ma), spreading rates and sediment thickness. Preliminary results indicate that the temperature of formation of calcium carbonate veins place a strong control on achieving a successful U/Pb isochron. This is likely related to the temperature dependent geochemical evolution of basement fluids due to fluid-rock reaction, and the partitioning of U and Pb into calcite/aragonite. Successful U/Pb isochrons have been achieved for a range of crustal ages and spreading rates, and indicate that calcium carbonate precipitation occurs within 25Myrs of crustal formation. This is substantially shorter than 65Ma, the average extent of the conductive heat flow anomaly, and will allow for more robust estimates of the contribution of hydrothermal chemical fluxes to global geochemical cycles.

  11. Peralkaline fluid composition in equilibrium with K-feldspar, muscovite and quartz at 10 kbar and 700°C: Al transport in crustal fluids

    NASA Astrophysics Data System (ADS)

    Wohlers, A.; Manning, C. E.

    2012-04-01

    Aluminum is commonly regarded as one of the least soluble elements during metamorphic and metasomatic processes. However, abundant field evidence suggests that aluminum transport can occur in natural hydrothermal processes. For example, late formed aluminumsilicate-bearing and muscovite-bearing veins are widely observed in high-grade metamorphic rocks, and provide a persuasive argument for considerable mobility of aluminum in aqueous fluid. The present study explores the fluid composition coexisting with K-feldspar (K-fsp), muscovite (ms), corundum (co) and quartz (qz) at deep crustal metamorphic conditions, using a piston cylinder device at 10 kbar and 700°C. Starting materials of natural microcline, quartz, synthetic corundum, reagent Al2O3 and KSi3O6.5 glass was used. Ms and K-fsp dissolve incongruently to co + fluid and ms + fluid, respectively. Fluid composition in equilibrium with co + ms and ms + K-fsp were located in experiments with and without qz. In quartz-absent experiments fluid composition with co+ms (I1) is mAl = 0.11, mK = 0.15, mSi = 0.44, and with K-fsp + ms (I2) mAl = 0.18, mK = 0.28 and mSi = 0.81, where mi is molality of the subscripted element. Fluid compositions with qz are: mAl = 0.08, mK = 0.11 and mSi = 1.18 (co + ms + qtz; II1) and mAl = 0.18, mK = 0.29 and mSi = 1.58 for (K-fsp + ms +qtz; II2). Measured fluid compositions are peralkaline (K/Al < 1.4). Bulk solubility of Al in pure H2O at this P and T is reported to be ~0.3 wt% [1], and increase to ~1.9 wt % Al in the presence of SiO2 [2]. This study shows that Al solubility is further enhanced by the presence of K and Si, increasing from ~4.07 wt% for (I1) to ~ 7.14 wt% at (I2). Presence of quartz enhances the bulk solubility from ~ 7.63 wt% (II1) to ~ 12.05 wt % at (II2). Results indicate that substantial aluminum transfer may occur at deep-crust metamorphic conditions in aqueous solutions equilibrated with common crustal bulk compositions such as metapelites and granites. Such high Al

  12. Genesis of jadeite-quartz rocks in the Yorii area of the Kanto Mountains, Japan

    NASA Astrophysics Data System (ADS)

    Fukuyama, Mayuko; Ogasawara, Masatsugu; Horie, Kenji; Lee, Der-Chuen

    2013-02-01

    This paper reports the results of U-Pb dating and REE (rare earth element) analysis of zircons separated from jadeite-quartz rocks within serpentinite mélanges in the Yorii area of the Kanto Mountains, Japan. These rocks contain jadeite, albite, and quartz, with minor aegirine-augite, zircon, monazite, thorite, allanite, and titanite. Mineral textures provide evidence of a jadeite + quartz = albite reaction during formation of these jadeite-quartz rocks. Zircon crystals separated from the jadeite-quartz rocks can be split into two distinct types, here named Types I and II, based on their morphology and REE concentrations. Type I zircons are prismatic and have fluid, jadeite, quartz, and albite inclusions. Those show positive Ce and negative Eu anomalies and HREE (heavy rare earth element) enriched chondrite normalized REE patterns and have higher REE concentrations than those generally found in magmatic zircons. Type I zircons would have precipitated from a fluid. Mineralogical observation provides that Type I zircon crystallized at the same timing of the formation of the jadeite-quartz rocks. Type II zircons are porous and have REE patterns indicative of a hydrothermal zircon. Both types of zircons are fluid-related. Type I zircons yield U-Pb ages of 162.2 ± 0.6 Ma, with an MSWD (mean square weighted deviation) of 1.4. At this time, Japan was still a part of the eastern margin of the Asian continent, with the subduction of the oceanic paleo-Pacific Plate leading to the formation of the Jurassic Mino-Tanba-Chichibu accretionary complex in Japan. The age data indicate that the jadeite-quartz rocks formed in a deep subduction zone environment at the same time as the formation of the Jurassic accretionary complex in a shallower near-trench subduction zone environment. The jadeite-quartz rocks contain high concentrations of Zr and Nb, with low LILE (large ion lithophile elements) concentrations, suggesting that the HFSE (high field strength elements) can be

  13. Experimental calibration of a Ti-in-quartz thermobarometer: an overview for applications to mylonites

    NASA Astrophysics Data System (ADS)

    Thomas, Jay

    2013-04-01

    an extensional terrane. Earth and Planetary Science Letters 303, 181-192 Grujic D, Stipp M, Wooden JL (2011) Thermometry of quartz mylonites: Importance of dynamic recrystallization on Ti-in-quartz reequilibration. Geochemistry, Geophysics, Geosystems 12, doi:10.1029/2010GC003368 Kidder S, Avouac J-P, Chan Y-C (2012) Application of titanium-in-quartz thermobarometry to greenschist facies veins and recrystallized quartzites in the Hsüehshan range, Taiwan. Solid Earth 4, 663-706

  14. Quartz resources in the Serra de Santa Helena formation, Brazil: A geochemical and technological study

    NASA Astrophysics Data System (ADS)

    Santos, Murilo Ferreira Marques dos; Fujiwara, Eric; Schenkel, Egont Alexandre; Enzweiler, Jacinta; Suzuki, Carlos Kenichi

    2014-12-01

    This study presents an evaluation of Brazilian quartz deposits of Corinto and Olhos D'água, in Minas Gerais State, as potential high purity raw material for the production of silica glass. Both deposits are part of the Serra de Santa Helena formation, which holds other quartz deposits. Several quartz samples from these mines were analyzed to evaluate their chemical purity, by determination of the content of trace elements by ICP-MS after acid digestion. The technological characteristics of the ores after flame-fusion into silica glass were evaluated according to their bubble generation and UV transparency. The results indicate that silica glass with chemistry suitable for crucible applications can be obtained from materials of both mines, and even optical grade silica glass can be manufactured using transparent ore from one of the mines. In addition, this work explores the trace elements composition of each mine, as well as their fluid inclusions, and characterizes the mines as being of hydrothermal origin. Small differences in the physical and chemical characteristics of quartz that could affect the technological behavior of the ores are related to the geological history of the mines and provide interesting insights regarding the exploration of other quartz resources within the same geological formation.

  15. Sagittal vein thrombosis caused by central vein catheter.

    PubMed

    Sabzi, Feridoun; Karim, Hosein; Heydar Pour, Behzad; Faraji, Reza

    2015-01-01

    Cerebral venous thrombosis, including thrombosis of cerebral veins and major dural sinuses, is an uncommon disorder in the general population. However, it has a higher frequency among patients younger than 40 years of age, patients with thrombophilia, pregnant patients or those receiving hormonal contraceptive therapy or has foreign body such as catheter in their veins or arterial system. In this case report, we described clinical and radiological findings in a patient with protein C-S deficiency and malposition of central vein catheter. PMID:25796028

  16. Evolution of the magmatic-hydrothermal acid-sulfate system at Summitville, Colorado: Integration of geological, stable-isotope, and fluid-inclusion evidence

    USGS Publications Warehouse

    Bethke, P.M.; Rye, R.O.; Stoffregen, R.E.; Vikre, P.G.

    2005-01-01

    The Summitville Au-Ag-Cu deposit is a classic volcanic dome-hosted high-sulfidation deposit. It occurs in the Quartz Latite of South Mountain, a composite volcanic dome that was emplaced along the coincident margins of the Platoro and Summitville calderas at 22.5??0.5 Ma, penecontemporaneous with alteration and mineralization. A penecontemporaneous quartz monzonite porphyry intrusion underlies the district and is cut and overlain by pyrite-quartz stockwork veins with traces of chalcopyrite and molybdenite. Alteration and mineralization proceeded through three hypogene stages and a supergene stage, punctuated by at least three periods of hydrothermal brecciation. Intense acid leaching along fractures in the quartz latite produced irregular pipes and lenticular pods of vuggy silica enclosed sequentially by alteration zones of quartz-alunite, quartz-kaolinite, and clay. The acid-sulfate-altered rocks host subsequent covellite+enargite/luzonite+chalcopyrite mineralization accompanied by kaolinite, and later barite-base-metal veins, some containing high Au values and kaolinite. The presence of both liquid- and vapor-rich fluid inclusions indicates the episodic presence of a low-density fluid at all levels of the system. In the mineralized zone, liquid-rich fluid inclusions in healed fractures in quartz phenocrysts and in quartz associated with mineralization homogenize to temperatures between 160 and 390 ??C (90% between 190 and 310 ??C), consistent with the range (200-250 ??C) estimated from the fractionation of sulfur isotopes between coexisting alunite and pyrite. A deep alunite-pyrite pair yielded a sulfur-isotope temperature of 390 ??C, marking a transition from hydrostatic to lithostatic pressure at a depth of about 1.5 km. Two salinity populations dominate the liquid-rich fluid inclusions. One has salinities between 0 and 5 wt.% NaCl equivalent; the other has salinities of up to 43 wt.% NaCl equivalent. The occurrence of high-salinity fluid inclusions in vein

  17. The Trans-Atlantic Geotraverse hydrothermal field: A hydrothermal system on an active detachment fault

    NASA Astrophysics Data System (ADS)

    Humphris, Susan E.; Tivey, Margaret K.; Tivey, Maurice A.

    2015-11-01

    Over the last ten years, geophysical studies have revealed that the Trans-Atlantic Geotraverse (TAG) hydrothermal field (26°08‧N on the Mid-Atlantic Ridge) is located on the hanging wall of an active detachment fault. This is particularly important in light of the recognition that detachment faulting accounts for crustal accretion/extension along a significant portion of the Mid-Atlantic Ridge, and that the majority of confirmed vent sites on this slow-spreading ridge are hosted on detachment faults. The TAG hydrothermal field is one of the largest sites of high-temperature hydrothermal activity and mineralization found to date on the seafloor, and is comprised of active and relict deposits in different stages of evolution. The episodic nature of hydrothermal activity over the last 140 ka provides strong evidence that the complex shape and geological structure of the active detachment fault system exerts first order, but poorly understood, influences on the hydrothermal circulation patterns, fluid chemistry, and mineral deposition. While hydrothermal circulation extracts heat from a deep source region, the location of the source region at TAG is unknown. Hydrothermal upflow is likely focused along the relatively permeable detachment fault interface at depth, and then the high temperature fluids leave the low-angle portion of the detachment fault and rise vertically through the highly fissured hanging wall to the seafloor. The presence of abundant anhydrite in the cone on the summit of the TAG active mound and in veins in the crust beneath provides evidence for a fluid circulation system that entrains significant amounts of seawater into the shallow parts of the mound and stockwork. Given the importance of detachment faulting for crustal extension at slow spreading ridges, the fundamental question that still needs to be addressed is: How do detachment fault systems, and the structure at depth associated with these systems (e.g., presence of plutons and/or high

  18. Impact polymorphs of quartz: experiments and modelling

    NASA Astrophysics Data System (ADS)

    Price, M. C.; Dutta, R.; Burchell, M. J.; Cole, M. J.

    2013-09-01

    We have used the light gas gun at the University of Kent to perform a series of impact experiments firing quartz projectiles onto metal, quartz and sapphire targets. The aim is to quantify the amount of any high pressure quartz polymorphs produced, and use these data to develop our hydrocode modelling to enable the predict ion of the quantity of polymorphs produced during a planetary scale impact.

  19. Volatile evolution of ore fluids in Coeur D'Alene veins during metamorphism of the Belt Basin

    SciTech Connect

    Hofstra, A.H.; Landis, G.P.; Leach, D.L.

    1985-01-01

    Two major vein types are recognized in the Coeur d'Alene district, Idaho and Montana. Early Zn-rich veins fill axial plane shears of WNW-trending folds in competent lithologies of Prichard Fm. and Ravalli Group metasediments. Later, Ag-rich veins occur predominantly in upper Revett Fm. quartzite in east- to northeast-trending fractures. Both vein types were deposited from fluids generated during regional greenschist grade metamorphism. Volatile composition of individual fluid inclusions in quartz and sphalerite from these veins were estimated using microthermometry and laser Raman spectroscopy. A high-sensitivity quadrupole mass spectrometer was used to obtain quantitative analyses of fluid extracted from whole crystals. Fluid inclusions from both vein types generally contain less than 10 mole % total gases and 5-10 eq. wt. % NaCl. However, fluid inclusion in Zn-rich veins contain greater concentrations of CH/sub 4/, short chain hydrocarbons, and N/sub 2/ compared to Ag-rich veins in which CO/sub 2/ is the dominant volatile component. The observed change in volatile compositions during metamorphism is consistent with a shift from relatively reducing to oxidizing conditions. The change from Zn- to Ag-rich veins may reflect the combined effects of a) volatile evolution of the metamorphic fluids through time, b) episodic development of large fractures with different orientations, and c) different lithologies contributing metamorphic fluids to these fractures.

  20. A Single-Crystalline Mesoporous Quartz Superlattice.

    PubMed

    Matsuno, Takamichi; Kuroda, Yoshiyuki; Kitahara, Masaki; Shimojima, Atsushi; Wada, Hiroaki; Kuroda, Kazuyuki

    2016-05-10

    There has been significant interest in the crystallization of nanostructured silica into α-quartz because of its physicochemical properties. We demonstrate a single-crystalline mesoporous quartz superlattice, a silica polymorph with unprecedentedly ordered hierarchical structures on both the several tens of nanometers scale and the atomic one. The mesoporous quartz superlattice consists of periodically arranged α-quartz nanospheres whose crystalline axes are mostly oriented in an assembly. The superlattice is prepared by thermal crystallization of amorphous silica nanospheres constituting a colloidal crystal. We found that the deposition of a strong flux of Li(+) only on the surface of silica nanospheres is effective for crystallization. PMID:27060365

  1. Exsolved magmatic fluid and its role in the formation of comb-layered quartz at the Cretaceous Logtung W-Mo deposit, Yukon Territory, Canada

    USGS Publications Warehouse

    Lowenstern, J. B.; Sinclair, W.D.

    1996-01-01

    Comb-layered quartz is a type of unidirectional solidification texture found at the roofs of shallow silicic intrusions that are often associated spatially with Mo and W mineralisation. The texture consists of multiple layers of euhedral, prismatic quartz crystals (Type I) that have grown on subplanar aplite substrates. The layers are separated by porphyritic aplite containing equant phenocrysts of quartz (Type II), which resemble quartz typical of volcanic rocks and porphyry intrusions. At Logtung, Type I quartz within comb layers is zoned with respect to a number of trace elements, including Al and K. Concentrations of these elements as well as Mn, Ti, Ge, Rb and H are anomalous and much higher than found in Type II quartz from Logtung or in igneous quartz reported elsewhere. The two populations appear to have formed under different conditions. The Type II quartz phenocrysts almost certainly grew from a high-silica melt between 600 and 800??C (as ??-quartz); in contrast, the morphology of Type I quartz is consistent with precipitation from a hydrothermal solution, possibly as ??-quartz grown below 600??C. The bulk compositions of comb-layered rocks, as well as the aplite interlayers, are consistent with the hypothesis that these textures did not precipitate solely from a crystallising silicate melt. Instead, Type I quartz may have grown from pockets of exsolved magmatic fluid located between the magma and its crystallised border. The Type II quartz represents pre-existing phenocrysts in the underlying magma; this magma was quenched to aplite during fracturing/degassing events. Renewed and repeated formation and disruption of the pockets of exsolved aqueous fluid accounts for the rhythmic banding of the rocks.

  2. Hydrothermal alteration in oceanic ridge volcanics: A detailed study at the Galapagos Fossil Hydrothermal Field

    SciTech Connect

    Ridley, W.I.; Perfit, M.R.; Smith, M.F.; Jonasson, I.R.

    1994-06-01

    The Galapagos Fossil Hydrothermal Field is composed of altered oceanic crust and extinct hydrothermal vents within the eastern Galapagos Rift between 85{degree}49 feet W and 85{degree} 55 feet W. The discharge zone of the hydrothermal system is revealed along scarps, thus providing an opportunity to examine the uppermost mineralized, and highly altered interior parts of the crust. Altered rocks collected in situ by the submersible ALVIN show complex concentric alteration zones. Microsamples of individual zones have been analysed for major/minor, trace elements, and strontium isotopes in order to describe the complex compositional details of the hydrothermal alteration. Interlayered chlorite-smectite and chlorite with disequilibrium compositions dominate the secondary mineralogy as replacement phases of primary glass and acicular pyroxene. Phenocrysts and matrix grains of plagioclase are unaffected during alteration. Using a modification of the Gresens` equation we demonstrate that the trivalent rare earth elements (REEs) are relatively immobile, and calculate degrees of enrichment and depletion in other elements. Strontium isotopic ratios increase as Sr concentrations decrease from least-altered cores to most-altered rims and cross-cutting veins in individual samples, and can be modeled by open system behaviour under low fluid-rock ratio (<10) conditions following a period of lower-temperature weathering of volcanics within the rift zone. The complex patterns of element enrichment and depletion and strontium isotope variations indicate mixing between pristine seawater and ascending hot fluids to produce a compositional spectrum of fluids. If, as suggested here, the discharge zone alteration occurred under relatively low fluid-rock ratios, then this shallow region must play an important role in determining the exit composition of vent fluids in marine hydrothermal systems. 50 refs., 10 figs., 4 tabs.

  3. Hydrothermal alteration in oceanic ridge volcanics: A detailed study at the Galapagos Fossil Hydrothermal Field

    USGS Publications Warehouse

    Ridley, W.I.; Perfit, M.R.; Josnasson, I.R.; Smith, M.F.

    1994-01-01

    The Galapagos Fossil Hydrothermal Field is composed of altered oceanic crust and extinct hydrothermal vents within the eastern Galapagos Rift between 85??49???W and 85??55???W. The discharge zone of the hydrothermal system is revealed along scarps, thus providing an opportunity to examine the uppermost mineralized, and highly altered interior parts of the crust. Altered rocks collected in situ by the submersible ALVIN show complex concentric alteration zones. Microsamples of individual zones have been analysed for major/minor, trace elements, and strontium isotopes in order to describe the complex compositional details of the hydrothermal alteration. Interlayered chlorite-smectite and chlorite with disequilibrium compositions dominate the secondary mineralogy as replacement phases of primary glass and acicular pyroxene. Phenocrysts and matrix grains of plagioclase are unaffected during alteration. Using a modification of the Gresens' equation we demonstrate that the trivalent rare earth elements (REEs) are relatively immobile, and calculate degrees of enrichment and depletion in other elements. Strontium isotopic ratios increase as Sr concentrations decrease from least-altered cores to most-altered rims and cross-cutting veins in individual samples, and can be modeled by open system behaviour under low fluid-rock ratio (< 10) conditions following a period of lower-temperature weathering of volcanics within the rift zone. The complex patterns of element enrichment and depletion and strontium isotope variations indicate mixing between pristine seawater and ascending hot fluids to produce a compositional spectrum of fluids. The precipitation of base-metal sulfides beneath the seafloor is probably a result of fluid mixing and cooling. If, as suggested here, the discharge zone alteration occurred under relatively low fluid-rock ratios, then this shallow region must play an important role in determining the exit composition of vent fluids in marine hydrothermal systems

  4. Vein matching using artificial neural network in vein authentication systems

    NASA Astrophysics Data System (ADS)

    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.

  5. Quartz-tourmaline orbicules: Record of magmatic melt immiscibility in the Land's End granite, SW England

    NASA Astrophysics Data System (ADS)

    Drivenes, Kristian; Larsen, Rune; Müller, Axel; Sorensen, Bjorn; Wiedenbeck, Michael; Raanes, Morten

    2014-05-01

    Spherical quartz-tourmaline aggregations are a common sight throughout the Cornubian batholith in SW England. In the outer parts of the Land's End granite smaller rounded orbicules occur in a coarse-grained megacrystic biotite granite. The interior parts of the orbicules show poikilittic textures with fine-grained euhedral quartz chadacrysts enclosed by skeletal tourmaline oikocrysts, with outer zones showing typical replacement textures. Cathodoluminescence of quartz show at least two growth stages after the megacrystic stage. The quartz phenocrysts show an even, concentric zoning pattern, sometimes with a darker core indicating growth during stable physiochemical conditions. The orbicular quartz is strongly zoned with bright cores and darker rims, similar to the fine-grained quartz in the granite matrix. Ti content of quartz corresponds to the CL zoning, with 125 - 180 µg/g in the bright cores and 60 - 80 in the darker main stage orbicular quartz. Tourmaline in the orbicules is weakly zoned form dark to pale brown, but the zoning is more pronounced compared to tourmaline in the granite matrix. Chemically, both are well within the schorl field, and cannot be differentiated based on major elements. The B-isotope signature is also overlapping. Matrix tourmaline has higher Sc and V content, but lower Nb, Ta and Sn, and matrix and orbicule tourmaline can be distinguished using trace elements. The geometry and composition of the orbicules is difficult to explain by fractional crystallization alone, since the total FeO content of the granite is low, and Fe is bound primarily to magmatic phases such as ilmenite and biotite. A prolonged fractional crystallization sequence would have depleted the magma in respect to Fe, and Fe derived from breakdown of nearby biotite is not sufficient to stabilize orbicule tourmaline. Orbicular tourmaline is conspicuously different, both chemically and texturally, from the typical hydrothermal tourmaline in the area, and replacement by an

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

    NASA Astrophysics Data System (ADS)

    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

  7. The origin of massive hydrothermal alterations: what drives fluid flow?

    NASA Astrophysics Data System (ADS)

    Gomez-Rivas, Enrique; Bons, Paul D.; Martín-Martín, Juan-Diego; Corbella, Mercè; Stafford, Sherry L.; Griera, Albert; Teixell, Antonio; Salas, Ramón; Travé, Anna

    2014-05-01

    hydrofractures (Bons, 2001). The main question is whether fast flow leaves recognizable signs, like hydrofractures of different scales and hydraulic breccias. We estimate fluid pressures reached at the reaction site, and discuss whether they are high enough to break the host rock, according to its petrophysical properties. Thermal convection could have driven pervasive fluid flow at lower flow rates, keeping the fluid warm and allowing time for the rock to react. But this mechanism would have required a shallow and very large intrusion or an anomalous geothermal gradient in order to activate flow by convection. This contribution presents a quantitative analysis of these hypotheses, and discusses their plausibility. Bons, P.D., 2001. The formation of large quartz veins by rapid ascent of fluids in mobile hydrofractures. Tectonophysics 336, 1-17. Gomez-Rivas, E., Corbella, M., Martín-Martín, J.D., Stafford, S.L., Teixell, A., Bons, P.D., Griera, A. and Cardellach, E. 2014. Reactivity of dolomitizing fluids and Mg source evaluation of fault-controlled dolomitization at the Benicàssim outcrop analogue (Maestrat Basin, E Spain). Marine and Petroleum Geology, in press.

  8. Hepatoportography via the Umbilical Vein

    PubMed Central

    White, J. J.; Skinner, G. B.; MacLean, L. D.

    1966-01-01

    The umbilical vein in adults is patent but collapsed. There is a membranous valve at its entrance into the left portal vein. Cannulation of the portal vein via the umbilical vein permits direct access to the portal system for portography and hepatography. This procedure was performed under local or general anesthesia in 30 patients and was successful in 22. It is useful in the investigation of patients with portal hypertension, and suspected intrahepatic tumours or abscesses. It gives excellent contrast visualization of the liver and definition of lesions as small as 1.0 cm. This technique is superior to both hepatic scanning and splenoportography. ImagesFig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11 PMID:5924949

  9. How Are Varicose Veins Treated?

    MedlinePlus

    ... Intramural Research Research Resources Research Meeting Summaries Technology Transfer Clinical Trials What Are Clinical Trials? Children & Clinical ... shun) therapy uses lasers or radiowaves to create heat to close off a varicose vein. Your doctor ...

  10. Formation of Archean batholith-hosted gold veins at the Lac Herbin deposit, Val-d'Or district, Canada: Mineralogical and fluid inclusion constraints

    NASA Astrophysics Data System (ADS)

    Rezeau, Hervé; Moritz, Robert; Beaudoin, Georges

    2016-07-01

    The Lac Herbin deposit consists of a network of mineralized, parallel steep-reverse faults within the synvolcanic Bourlamaque granodiorite batholith at Val-d'Or in the Archean Abitibi greenstone belt. There are two related quartz-tourmaline-carbonate fault-fill vein sets in the faults, which consist of subvertical fault-fill veins associated with subhorizontal veins. The paragenetic sequence is characterized by a main vein filling ore stage including quartz, tourmaline, carbonate, and pyrite-hosted gold, chalcopyrite, tellurides, pyrrhotite, and cubanite inclusions. Most of the gold is located in fractures in deformed pyrite and quartz in equilibrium with chalcopyrite and carbonates, with local pyrrhotite, sphalerite, galena, cobaltite, pyrite, or tellurides. Petrography and microthermometry on quartz from the main vein filling ore stage reveal the presence of three unrelated fluid inclusion types: (1) gold-bearing aqueous-carbonic inclusions arranged in three-dimensional intragranular clusters in quartz crystals responsible for the main vein filling stage, (2) barren high-temperature, aqueous, moderately saline inclusions observed in healed fractures, postdating the aqueous-carbonic inclusions, and considered as a remobilizing agent of earlier precipitated gold in late fractures, and (3) barren low-temperature, aqueous, high saline inclusions in healed fractures, similar to the crustal brines reported throughout the Canadian Shield and considered to be unrelated to the gold mineralization. At the Lac Herbin deposit, the aqueous-carbonic inclusions are interpreted to have formed first and to represent the gold-bearing fluid, which were generated contemporaneous with regional greenschist facies metamorphism. In contrast, the high-temperature aqueous fluid dissolved gold from the main vein filling ore stage transported and reprecipitated it in late fractures during a subsequent local thermal event.

  11. Quartz-sericite and argillic alterations at the Peschanka Cu-Mo-Au deposit, Chukchi Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Marushchenko, L. I.; Baksheev, I. A.; Nagornaya, E. V.; Chitalin, A. F.; Nikolaev, Yu. N.; Kal'ko, I. A.; Prokofiev, V. Yu.

    2015-05-01

    The porphyry Peschanka copper-molybdenum-gold deposit and the Nakhodka ore field located in the Baimka ore trend on the western Chukchi Peninsula are spatially related to monzonitic rocks of the Early Cretaceous Egdykgych Complex. Two types of quartz-sericite metasomatic rocks (QSR) have been identified at both the deposits and the ore field: (I) chlorite-quartz-muscovite rock with bornite and chalcopyrite (porphyry type) and (II) tourmaline-quartz-carbonate-muscovite ± phengite rock accompanied by veins with base-metal mineralization (subepithermal or transitional type), as well as carbonate-quartz-illite rock (argillic alteration) accompanied by veins with precious metal mineralization (epithermal type). The QSR I chlorite evolves from chamosite to clinochlore, which is caused by increasing H2S activity in mineralizing fluid and precipitation of sulfide minerals. The QSR I clinochlore is significantly depleted in silica as compared with that from the rocks affected by argillic alteration. The chemical composition of muscovite from both quartz-sericite alterations is similar. The QSR II carbonates evolve from calcite through dolomite to siderite, which results from the increasing activity of CO2 followed by the decreasing activity of H2S in mineralizing fluid. The Mn content in dolomite is similar to that in beresite (quartz-muscovite-carbonate-pyrite metasomatic rock) of the intrusion-related gold deposits. Illite from argillic alteration is depleted in Al as compared with that of postvolcanic epithermal Au-Ag deposits. However, carbonates from the discussed argillic alteration rhodochrosite and Mn-rich dolomite are similar to those from quartz-illite rock at postvolcanic epithermal Au-Ag deposits.

  12. Hydrothermal Alteration in the Logatchev Hydrothermal Field: Implications From Secondary Mineral Assemblages and Mineral Chemistry

    NASA Astrophysics Data System (ADS)

    Lackschewitz, K. S.; Augustin, N.; Devey, C. W.; Eisenhauer, A.; Garbe-Schoenberg, D.; James, R.

    2005-12-01

    We present new data on secondary mineral assemblages, clay and whole rock chemistry and clay mineral strontium and lithium isotopic compositions of altered rocks and sediments from the active, ultramafic-hosted Logatchev hydrothermal field reflecting various alteration conditions (e.g. fluid mixing, water-rock interaction). The altered ultramafic rocks are mainly consist of lizardite, chrysotile whereas magnetite and pyrite are minor minerals. Chlorite, chlorite-smectite mixed-layer (e.g., corrensite), smectite and talc are additional common phases in the clay fraction of most of these samples.Iron-hydroxides and iron sulfides are the main components of the hydrothermal crusts, with some amounts of pyroxene, chlorite, illite and pyrite. The hydrothermal sediments beneath the crusts are characterized by quartz, smectite and chlorite as main minerals. Analyses of clay separates representing a variety of alteration styles demonstrates that significant and characteristic changes in the bulk rock chemical composition are associated with various alteration conditions. The elements Cr, Cu, Pb and U appears to have a general enrichment in the lizardite and chlorite concentrates in comparison to a depleted mantle. 87Sr/86Sr ratios of clay concentrates vary between 0.7083 and 0.7096 suggesting that the clays either formed as a result of seawater alteration or hydrothermal alteration with various portions of seawater. The strontium isotopic ratio of a chlorite sample from hydrothermal sediments beneath the hydrothermal crust is much lower than the isotopic data reported for the lizardites suggesting precipitation from fluid with lower seawater content. The Li isotopic composition (δ7Li) of the clay separates varies between -5.4 and +6.4‰. Thus, the clays are enriched in 6Li relative to both seawater (~31‰) and hydrothermal vent fluids from the Logatchev field (~6‰) suggesting that 6Li is preferentially retained in alteration products. When considered together with the

  13. Sealed-in-quartz resistance heater

    NASA Technical Reports Server (NTRS)

    Miller, C. G.; Stephens, J. B.

    1980-01-01

    Electric resistance quartz heater operates at 1,400 F without developing excessively hot spots that can fail prematurely. Since resistance element is sealed in quartz, heater can be used in hostile environments. Sealed construction also keeps heater from contaminating heated object.

  14. Precise Sealing of Fused-Quartz Ampoules

    NASA Technical Reports Server (NTRS)

    Debnan, W. J. J.; Clark, I. O.

    1982-01-01

    New technique rapidly evacuates and seals fused-quartz ampoule with precise clearance over contents without appreciably thinning ampoule walls. Quartz plug is lowered into working section of ampoule after ampoule has been evacuated. Plug is then fused to ampoule walls, forming vacuum seal. New technique maintains wall strength and pumping speed.

  15. The Quartz Analog Watch: A Wonder Machine.

    ERIC Educational Resources Information Center

    Crane, H. Richard, Ed.

    1993-01-01

    Summarizes how a quartz watch works. Discusses the quartz crystal, its form, and how its frequency is set to a standard; the integrated circuit chip that drives the crystal in vibration, scales its frequency down, and forms pulses that turn the motor; and the motor that drives the gear train that turns the hands. (ZWH)

  16. Progressive hydrothermal alteration of feldspars from the Comstock Lode Region, Nevada: Submicron elemental imaging by Time of Flight-SIMS

    NASA Astrophysics Data System (ADS)

    Handler, M. R.; Vicenzi, E. P.; Sorensen, S. S.

    2002-05-01

    Time of Flight-Secondary Ionization Mass Spectrometry (ToF-SIMS) allows elemental mapping and depth profiling at lateral and depth resolutions of several hundred nanometers, with near-simultaneous acquisition of the entire elemental mass range and extending to larger hydrocarbon molecules. ToF-SIMS has been greatly utilized by surface scientists, but has rarely been used in terrestrial geosciences (e.g. [1]). Essentially a surface imaging technique, with shallow depth profiling abilities, it is ideal for investigating the distribution of elements and molecules (e.g. OH) on mineral surfaces, thin films [1], around fluid inclusions, and to trace chemical changes during weathering or hydrothermal alteration. To illustrate the potential of this analytical technique we highlight the progressive hydrothermal alteration of feldspars in the host andesites of the Comstock Lode paleohydrothermal system, Nevada. The Miocene Comstock Lode and related Ag-Au deposits are hosted mainly within Miocene Alta andesites, which were extensively sampled in the 1880s by G.F. Becker[2]. A sub-suite of these samples from the Sutro Tunnel document progressive hydrothermal alteration, with whole rock δ 18O values progressing from ~ +6 ‰ in distal andesites to -1.5 ‰ at the Coryell Lode [3]. The andesites are porphyritic with up to 50% feldspar phenocrysts, and minor mafic phases. Feldspar phenocrysts show systematic progression of alteration and replacement textures with decreasing whole rock δ 18O values and increasing proximity to the Coryell Lode. Relatively fresh igneous zoned phenocrysts (An35-55) grade into grains with fluid inclusions, crosscutting calcite +/- quartz veins, and increasingly complex reaction rims. Chemical alteration of feldspar progresses along cracks filled with fluid inclusions. Within 400 m of the Coryell Lode, feldspar phenocrysts have fully recrystallized, following crystallographic controls: Ab98-90 + An58-68, +/- sericite +/- calcite. A combination of BSE

  17. Hydrothermal alteration and sulfide mineralization in gabbroids of the Markov Deep (Mid-Atlantic Ridge, 6° N)

    NASA Astrophysics Data System (ADS)

    Sharkov, E. V.; Abramov, S. S.; Simonov, V. A.; Krinov, D. I.; Skolotnev, S. G.; Bel'Tenev, V. E.; Bortnikov, N. S.

    2007-12-01

    A new type of sulfide occurrence related to metasomatically altered brecciated gabbroids has been studied at the Sierra Leone site situated in the axial rift valley of the Mid-Atlantic Ridge (Markov Deep, 6° N). Two associations of plutonic, subvolcanic, and volcanic rocks were dredged: (1) mid-ocean ridge basalts (MORB) and their intrusive analogues and (2) rocks of the silicic Fe-Ti-oxide series with dominating gabbronorites and sporadic trondhjemites. Almost all igneous rocks at the Sierra Leone site are enriched in Pb, Cu, U, Ga, Ta, Nb, Cs, and Rb and depleted in Zr, Th, and Hf. The rocks of the Fe-Ti-oxide series are enriched in Zn, Sn, and Mo and depleted in Ni and Cr. The main ore-bearing zone is situated at the foot of the eastern wall of the deep, where it is hosted in cataclastic hornblende gabbro and gabbronorite of the Fe-Ti-oxide series. Ore mineralization in metasomatically altered rocks is composed of quartz-sulfide and prehnite-sulfide veinlets, disseminated sulfide, and veined copper sulfide ore. The ore consists of pyrite, chalcopyrite, sphalerite, pyrrhotite, bornite, chalcocite, and digenite. The δ34S value of sulfides varies from 3.0 to 15.3‰. At the foot of the eastern wall of the Markov Deep, directly downslope from the ore-bearing zone, loose sediments contain grains of native Cu, Pb, Zn, and Sn and intermetallic compounds (isoferroplatinum, tetraferroplatinum, and brass) apparently derived from the ore. Mineral assemblages of ore-bearing metasomatic rocks and fluid inclusions therein were studied. Ore metasomatism developed under a low oxygen potential within a temperature interval from 400 to 160°C, though initial hydrothermal alteration of rocks proceeded at temperatures of 800-450°C. The temperature of stringer-disseminated ore mineralization is estimated at 170-280°C. The hydrothermal fluids are considered to be of magmatic origin; as the hydrothermal system evolved, they became diluted with seawater that was contained in

  18. Uranium-series age determination of calcite veins, VC-1 drill core, Valles Caldera, New Mexico

    SciTech Connect

    Sturchio, N.C.

    1988-06-10

    Uranium-series analysis (/sup 238/U--/sup 234/U--/sup 230/Th) of 13 calcite veins from the hydrothermally altered Madera Limestone in the VC-1 drill core was performed to determine the ages of the veins and their relation to the Valles hydrothermal system. Thermal water from VC-1 and two hot springs in San Diego Canyon was analyzed for U and (/sup 234/U//sup 238/U) to help evaluate the constancy of initial (/sup 234/U//sup 238/U). The (/sup 230/Th//sup 234/U) age of one of the veins is /similar to/95 kyr, and those of two other veins are /similar to/230 and /similar to/250 kyr. Five of the veins have near equilibrium (/sup 230/Th//sup 234/U) and are probably older than /similar to/0.3 m.y. Uranium concentrations in the remaining veins are too low for analysis by the ..cap alpha..-spectrometry techniques employed in this study. Of the five veins near (/sup 230/Th//sup 234/U) equilibrium, suggesting ages greater than /similar to/1.0 m.y., but one has (/sup 234/U//sup 238/U) = 1.15, suggesting an age between /similar to/0.3 and /similar to/1.0 m.y. Calculated initial (/sup 234/U//sup 238/U) of the veins yielding relatively young ages are neither equal to each other nor to (/sup 234/U//sup 238/U) in thermal water from VC-1, indicating inconstancy of initial (/sup 234/U//sup 238/U) tht may be related to variations in groundwater mixing proportions. Three of the four veins that yield relatively young ages consist of coarse, sparry, vuggy calcite, suggesting that this may be the type of calcite vein which forms under conditions resembling those encountered presently in VC-1. The analytical data are consistent with closed-system behavior of U and Th in the VC-1 calcite veins. copyright American Geophysical Union 1988

  19. Deltoid Branch of Thoracoacromial Vein

    PubMed Central

    Su, Ta-Wei; Wu, Ching-Feng; Fu, Jui-Ying; Ko, Po-Jen; Yu, Sheng-Yueh; Kao, Tsung-Chi; Hsieh, Hong-Chang; Wu, Ching-Yang

    2015-01-01

    Abstract An entry vessel is crucial for intravenous port implantation. A safe alternative entry vessel that can be easily explored is crucial for patients without feasible cephalic vein or for those who need port reimplantation because of disease relapse. In this study, we tried to analyze the safety and feasibility of catheter implantation via the deltoid branch of the thoracoacromial vein. From March 2012 to November 2013, 802 consecutive oncology patients who had received intravenous port implantation via the superior vena cava were enrolled in this study. The functional results and complications of different entry vessels were compared. The majority of patients (93.6%) could be identified as thoracoacromial vessel. The deltoid branch of the thoracoacromial vein is located on the medial aspect of the deltopectoral groove beneath the pectoralis major muscle (85.8%) and in the deep part of the deltopectoral groove (14.2%). Due to the various calibers employed and tortuous routes followed, we utilized 3 different methods for catheter implantation, including vessel cutdown (47.4%), wire assisted (17.9%), and modified puncture method (34.6%). The functional results and complication rate were similar to other entry vessels. The deltoid branch of the thoracoacromial vein is located in the neighborhood of the cephalic vein. The functional results of intravenous port implantation via the deltoid branch of the thoracoacromial vein are similar to other entry vessels. It is a safe alternative entry vessel for intravenous port implantation. PMID:25929903

  20. Different carbon reservoirs of auriferous fluids in African Archean and Proterozoic gold deposits? Constraints from stable carbon isotopic compositions of quartz-hosted CO2-rich fluid inclusions

    NASA Astrophysics Data System (ADS)

    Lüders, Volker; Klemd, Reiner; Oberthür, Thomas; Plessen, Birgit

    2015-04-01

    Stable carbon (and when present, nitrogen) isotope ratios of fluid inclusions in quartz from selected gold deposits in Ghana and Zimbabwe have been analyzed using a crushing device interfaced to an isotopic ratio mass spectrometer (IRMS) in order to constrain possible sources of the auriferous fluids. The study revealed a striking difference in stable carbon isotopic compositions of CO2 in quartz-hosted fluid inclusions from Archean and Paleoproterozoic orogenic gold deposits and points to diverse sources of CO2 in the studied deposits. Whether this finding can be generalized for other Archean and Proterozoic orogenic gold deposits worldwide remains open. However, a significant CO2 contribution by mantle degassing can be ruled out for every deposit studied. Devolatilization of greenstone belt rocks is the most likely source for CO2 in some Archean Au deposits in Zimbabwe, whereas CO2 in Proterozoic vein-type Au deposits in the West African Craton is most likely derived from Corg-bearing metasedimentary rocks. The δ13CCO2 values of high-density CO2-rich, water-poor inclusions hosted in quartz pebbles from the world-class Au-bearing conglomerate deposits at Tarkwa (Ghana) differ considerably from the δ13CCO2 values of similar high-density CO2-rich inclusions in vein quartz from the giant Ashanti deposit (Ghana) and disprove the idea of derivation of the Tarkwaian quartz (and gold?) from an older equivalent to the Ashanti vein-type gold deposit.

  1. Quartz gauge response in ion radiation

    NASA Astrophysics Data System (ADS)

    Taylor, P. E.; Gilbert, P. H.; Kernthaler, C.; Lee, L. M.; Smith, E. A.; Reeder, S. T.; Anderson, M. U.

    1996-05-01

    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 while 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.

  2. Quartz gauge response in ion radiation

    SciTech Connect

    Taylor, P.E.; Gilbert, P.H.; Kernthaler, C.; Lee, L.M.; Smith, E.A.; Reeder, S.T.; Anderson, M.U.

    1995-12-31

    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 @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.

  3. Catalytic Hydrothermal Gasification

    SciTech Connect

    Elliott, Douglas C.

    2015-05-31

    The term “hydrothermal” used here refers to the processing of biomass in water slurries at elevated temperature and pressure to facilitate the chemical conversion of the organic structures in biomass into useful fuels. The process is meant to provide a means for treating wet biomass materials without drying and to access ionic reaction conditions by maintaining a liquid water processing medium. Typical hydrothermal processing conditions are 523-647K of temperature and operating pressures from 4-22 MPa of pressure. The temperature is sufficient to initiate pyrolytic mechanisms in the biopolymers while the pressure is sufficient to maintain a liquid water processing phase. Hydrothermal gasification is accomplished at the upper end of the process temperature range. It can be considered an extension of the hydrothermal liquefaction mechanisms that begin at the lowest hydrothermal conditions with subsequent decomposition of biopolymer fragments formed in liquefaction to smaller molecules and eventually to gas. Typically, hydrothermal gasification requires an active catalyst to accomplish reasonable rates of gas formation from biomass.

  4. Effect of hydrothermal heat treatment on magnetic properties of copper zinc ferrite rf sputtered films

    NASA Astrophysics Data System (ADS)

    Kaur, Jasmeet; Gadipelly, Thirupathi; Singh, R.

    2016-05-01

    The hydrothermal treatment to the nano-structured films can overcome the destruction of the films. The Cu-Zn Ferrite films were fabricated by RF-sputtering on quartz substrates. Subsequently, the as deposited films were heat treated using hydrothermal process. The X-ray diffraction pattern of the as-deposited and hydrothermal treated films indicate nano-crystalline cubic spinel structure. The amorphous nature of the films is removed after hydrothermal treatment with decreased crystallite size. The field emission scanning electron micrographs showed merged columnar growth for as deposited films, which changes to well define columns after hydrothermal heating. The homogeneous cluster distribution is observed in surface view of the hydrothermal treated films. Hydrothermal treated films show merging of in-plane and out of plane magnetization plots (M(H)) whereas the M(H) plots of as deposited films show angular dependence. The strong angular dependence is observed in the FMR spectra due to the presence of a uniaxial anisotropy in the films. The ferromagnetic interactions decrease in hydrothermal heated films due to the reduced shape anisotropy and crystallite size.

  5. Geology and geochemistry of the Mammoth breccia pipe, Copper Creek mining district, southeastern Arizona: Evidence for a magmatic-hydrothermal origin

    USGS Publications Warehouse

    Anderson, E.D.; Atkinson, W.W., Jr.; Marsh, T.; Iriondo, A.

    2009-01-01

    The Copper Creek mining district, southeastern Arizona, contains more than 500 mineralized breccia pipes, buried porphyry-style, copper-bearing stockworks, and distal lead-silver veins. The breccia pipes are hosted by the Copper Creek Granodiorite and the Glory Hole volcanic rocks. The unexposed Mammoth breccia pipe, solely recognized by drilling, has a vertical extent of 800 m and a maximum width of 180 m. The pipe consists of angular clasts of granodiorite cemented by quartz, chalcopyrite, bornite, anhydrite, and calcite. Biotite 40Ar/ 39Ar dates suggest a minimum age of 61.5??0.7 Ma for the host Copper Creek Granodiorite and 40Ar/39Ar dates on hydrothermal sericite indicate an age of 61.0??0.5 Ma for copper mineralization. Fluid inclusion studies suggest that a supercritical fluid with a salinity of approximately 10 wt.% NaCl equiv. condensed to a dilute aqueous vapor (1-2.8 wt.% NaCl equiv.) and a hypersaline brine (33.4-35.1 wt.% NaCl equiv.). Minimum trapping temperatures are 375??C and trapping depths are estimated at 2 km. Sulfur isotope fractionation of cogenetic anhydrite and chalcopyrite yields a temperature of mineralization of 469??25??C. Calculated oxygen and hydrogen isotope values for fluids in equilibrium with quartz and sericite range from 10.2??? to 13.4??? and -60??? to -39???, respectively, suggesting that the mineralizing fluid was dominantly magmatic. Evidence from the stable isotope and fluid inclusion analyses suggests that the fluids responsible for Cu mineralization within the Mammoth breccia pipe exsolved from a gray porphyry phase found at the base of the breccia pipe. ?? Springer-Verlag 2008.

  6. Hydrothermal systematics, alteration, and mineralization in the Grant Canyon, Bacon Flat, and Blackburn Oil Fields, Nevada - Intriguing Parallels with Carlin-Type gold deposits

    SciTech Connect

    Hulen, J.B.; Nielson, D.L. )

    1993-08-01

    Nevada's three known thermally active oil reservoirs-Blackburn, Bacon Flat, and Grand Canyon-share a surprisingly long list of essential attributes with the Carlin-type, low-grade, sediment-hosted gold deposits, particularly those of the Alligator Ridge mining district. Like these rich precious-metal ore bodies, the three fields (1) are hosted by Paleozoic carbonate and calcareous silici-clastic strata; (2) occur in structural or structural/stratigraphic traps sealed beneath shales or hydrothermally argillized and silicified tuffs and epiclastic debris, (3) have undergone intense fracturing and brecciation, as well as massive hydrothermal decalcification as major porosity-creating processes; (4) occupy rocks partly altered to or veined by the secondary-mineral assemblage quartz-kaolin-barite-pyrite-marcasite; (5) have a direct geothermal connection; (6) are enriched in the elements arsenic, antimony, mercury, thallium, and even contain significant traces of gold-up 50 ppb in altered Mississippian Chainmain Shale in the Blackburn field. Moreover, measured temperatures, as well as late-stage, fluid-inclusion homogenization temperatures (T[sub h]) at the fields-all in the range 100-135[degrees]C-fall within the fluid-inclusion T[sub h] span of 90-165[degrees]C recorded for multiple Alligator Ridge deposits. Fracture-controlled live oil and oil-bearing fluid inclusions in some of the Alligator Ridge ores provide further evidence of genetic similarities with the oil reservoirs. The authors suggest that the three oil fields could represent either weakly mineralized analogs of the gold deposits or an incipient phase in their evolution ultimately leading to ore mineralization.

  7. Geological setting and timing of the cassiterite vein type mineralization of the Kalima area (Maniema, Democratic Republic of Congo)

    NASA Astrophysics Data System (ADS)

    Dewaele, S.; Muchez, Ph; Burgess, R.; Boyce, A.

    2015-12-01

    The Central African Mesoproterozoic Karagwe-Ankole belt in the Great Lakes area (DRCongo, Rwanda, Burundi, Uganda and Tanzania) forms a metallogenic province that hosts a variety of granite-related mineralization, which contains cassiterite, columbite-tantalite, wolframite/ferberite, spodumene and beryl. The Kalima area in the Maniema province of the DRCongo forms one of the most important areas for cassiterite mineralization in the eastern part of the DRCongo, even after many decades of exploitation. The mineralization dominantly consists of quartz veins that are hosted in Mesoproterozoic metasediments at the contact with granitic rocks of the Kalima granite (Avuanga and Yubuli) or directly crosscutting these granitic rocks (Atondo). Only limited - and mainly unmineralized pegmatites - have been described in the Lutshurukuru area. Mineralized quartz veins - and some granite bodies - intruded following the regional tectonic foliation or existing fracture zones, confirming the late-to post-tectonic origin of the fertile granite system. The emplacement of the quartz veins resulted in an alteration of the metasedimentary and granitic host-rocks, mainly resulting in muscovitization, tourmalinization and silicification. Cassiterite itself formed relatively late during vein formation and is associated with muscovite in fractures in or along the margins of the quartz veins. 40Ar-39Ar age dating of muscovite of an unmineralized pegmatite from the Lutshurukuru area gave an excellent plateau age of 1024 ± 5.5 Ma, while the muscovite associated with mineralization gave plateau ages of 986 ± 5.3 Ma for the Atondo deposit and 992.4 ± 5.4 Ma for the Yubuli deposit. The rather large spread in ages between the supposed parental granite/pegmatite and quartz veins is interpreted to reflect different magmatic events in the evolution of a composite granite system, starting at ∼1020 Ma and ending with mineralized quartz vein formation at ∼990 Ma. The latter age corresponds with

  8. Earthquake rupturing as a mineralizing agent in hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Sibson, Richard H.

    1987-08-01

    Much fault-hosted epithermal mineralization is localized in dilational jogs between en echelon fault segments, as fissure veins or as hydrothermally cemented, high-dilation wall-rock breccias. Jog widths may range from millimetres to kilometres; vein textures record histories of incremental development. Perturbation or arrest of earthquake ruptures at dilational jogs has been observed and is believed to involve extensional fracturing at the rupture tip, locally reducing fluid pressure and inducing suctions opposing rapid slip transfer across the jog. This forced fissuring leads to brecciation by hydraulic implosion and to a concentrated fluid influx, allowing delayed slip transfer accompanied by aftershock activity. Within the southern San Andreas fault system, major dilational jogs extend throughout the seismogenic regime and form loci for magmatic-hydrothermal systems; they act as vertical pipelike conduits for enhanced fluid flow. Rupture termination at these structures has sometimes been followed by hydrothermal eruptions, suggesting that high-level boiling events are triggered by the arrest mechanism. It thus seems probable that episodic mineral deposition in the top 1 2 km of such jogs is induced by the dynamic effects of rupturing on the flanking strike-slip faults.

  9. COMBUSTION OF HYDROTHERMALLY TREATED COALS

    EPA Science Inventory

    The report gives results of an evaluation of: (1) the relationship of the combustion characteristics of hydrothermally treated (HTT) coals to environmental emissions, boiler design, and interchangeability of solid fuels produced by the Hydrothermal Coal Process (HCP) with raw coa...

  10. The Riviera Deposit: Endo-skarn and Vein-hosted W-MO-REE Mineralization in I-type Granites of the Cape Granite Suite, South Africa

    NASA Astrophysics Data System (ADS)

    Rozendaal, A.; Moyen, J.

    2009-05-01

    The blind Riviera deposit is located in the western Cape Province and was discovered by stream sediment sampling in the mid 1970's. Resources total 46 million metric tons assaying 0,216 per cent tungsten and 200 parts per million molybdenum, a marginal grade that has prohibited development into an open cast mine. Mineralization is mainly hosted by granitoids of the Riviera Pluton which intruded the regionally metamorphosed volcano-sedimentary Malmesbury Group. These granitoids form part of the Cape Granite Suite, a series of batholiths and plutons with S-, I- and A-type characteristics. The composite Riviera Pluton comprises a suite of metaluminous to slightly peraluminous granitoids. The rocks least affected by hydrothermal alteration are granodioritic to adamelitic in composition whereas the more altered host rocks include quartz-monzonite, granite and quartz syenite. As a whole the suite is subalkaline to K-calcalkaline and conforms to the characteristics of I-type granites. The pluton was emplaced into a dome-shaped interference structure, late in the Neoproterozoic Saldanian orogenic cycle. Alteration, particularly prevalent in the roof or cupola of the pluton, occurs as zones of pervasive sericitization, argillization, silicification and potassic alteration. Their spatial and temporal relationship is complex and indicates several superimposed alteration events. Wall rocks display limited alteration and have acted as an impermeable cap. The cross-cutting granitoid intrusions produced wall rock xenoliths of various dimensions consisting mainly of meta-carbonates displaying various stages of digestion. Economic concentrations of scheelite are spatially linked to these assimilations, particularly proximal to the wall rock contact. The occurrence of diagnostic minerals such as vesuvianite, hornblende, hedenbergite, grandite garnets define a typical endo-skarn association. Accessory minerals include pyrite, pyrrhotite, chalcopyrite, sphalerite and the LREE enriched

  11. Experimental and theoretical investigation of the production of HCl and some metal chlorides in magmatic/hydrothermal systems

    SciTech Connect

    Not Available

    1992-01-01

    In the calculations we have assumed that all apatites are magmatic. The presence of chlorite and altered plagioclase within the granite and quartz-monzodiorite suggests that alteration may play a role in leading to erroneous estimates of initial melt Cl and F for 2 reasons: (1) the apatites may in fact not be magmatic in origin, but are hydrothermal, and (2) the halogen signature of magmatic apatite may be changed due to subsolidus exchange with a hydrothermal fluid. We are currently endeavoring to develop criteria for determining whether apatite composition represents earlier or later stages of magmatic-hydrothermal development.

  12. Structural control and metamorphic setting of the shear zone-related Au vein mineralization of the Adola Belt (southern Ethiopia) and its tectono-genetic development

    NASA Astrophysics Data System (ADS)

    Worku, H.

    1996-10-01

    Structural study of the Adola Belt shows that most of its known and potential Au deposits occur in quartz veins which are localised within shear contacts between lithological units, and along major shear zones that divide the Adola Belt into different lithostructural domains. Analysis of the shear zone-related ore bodies and their host volcano-sedimentary succession and gneisses indicates that Au mineralization in the Adola Belt is pre-dated by two stages of deformation and a regional prograde metamorphism. The first deformation event (D 1) is a fold-and-thrust event which is characterised by low-angle thrusts, associated recumbent folds and axial planar S 1 foliation, and is related to nappe-style deformation. The second event (D 2) has folded and/or reactivated the thrust-related structures and formed upright folds and high-angle reverse shear zones and is related to the collision event. Gold mineralization occurred over a prolonged deformation history but is closely related to alteration, retrograde greenschistfacies assemblages and brittle-ductile deformation of late D 2 and D 3 transpressional shear zones that accommodate regional shortening both by crustal thickening and lateral displacement. The mineralization occurs in associated dilational jogs or bends that might have formed during the lateral or vertical expulsion. The Au-hosting shear zones are characterised by extensive development of heterogeneous mylonitic fault rocks which reveals that the accompanied deformation is characterised by processes that can increase the porosity and permeability of the rocks within the shear zones. This gave rise to further extensive dilatancy within the major dilational jogs and produced a suitable structural regime for vein-hosted Au mineralization. This implies that the Au mineralization is epigenetic in origin and that it resulted from precipitation from metamorphic hydrothermal fluids circulating through major shear zones and associated structures late during the

  13. Microstructural evolution in bitaxial crack-seal veins: A phase-field study

    NASA Astrophysics Data System (ADS)

    Ankit, Kumar; Urai, Janos L.; Nestler, Britta

    2015-05-01

    Bitaxial crack sealing by epitaxial crystal growth is the most common vein-forming process in Earth's crust, but the details of the microstructural processes in these are not well understood. Here we model the evolution of bitaxial crack-seal quartz veins in two and three dimensions, using the phase-field method. Our numerical simulations show the influence of different parameters, such as the obliquity of crack opening and crack location, grain size, and orientations on the evolving vein microstructure. We examine the underlying growth competition observed during epitaxial growth of quartz. Results show many similarities with natural microstructures such as stretched crystals and compare well with the previous numerical findings. As the ratio of crack aperture and matrix grain size for the present studies is chosen to be sufficiently large for growth competition to occur before complete sealing, it leads to the formation of crystal fragments along the crack-opening trajectory. We explain how such fragment trails act as potential indicators of the opening of crack-seal veins, if they are confirmed to be common in natural microstructures. Finally, we highlight the importance of accounting for the third dimension in the numerical simulations by analyzing the evolution of fluid connectivity in 2-D and 3-D during the sealing process.

  14. Carbon isotope evidence for a magmatic origin for Archaean gold-quartz vein ore deposits

    NASA Technical Reports Server (NTRS)

    Burrows, D. R.; Wood, P. C.; Spooner, E. T. C.

    1986-01-01

    Sediments from three sites in the Santa Barbara Basin were examined with a 160X power light microscope and TEM equipment to characterize the magnetostatic bacteria (MB) in the samples. Both the free magnetite and the crystals in the MB in the samples had lengths from 40-60 nm in length and increased in size from one end to the next. An intact magnetosome was also observed. Scanning the sediments with saturation isothermal remanent magnetization (SIRM) and altering field demagnetization techniques using a SQUID magnetometer yielded coercivity spectra which showed that the primary remanence carrier in the sediments was single domain magnetite. Although it is expected that the predominance of the bacterial magnetite component will decrease with depth in the open ocean basin, single-domain bacteria as old as 50 Myr have been observed in oceanic sediments.

  15. Fluid inclusion petrology and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414

    NASA Astrophysics Data System (ADS)

    Brandstätter, Jennifer; Kurz, Walter; Krenn, Kurt; Micheuz, Peter

    2016-04-01

    In this study, we present new data from microthermometry of fluid inclusions entrapped in hydrothermal veins along the Cocos Ridge from the IODP Expedition 344 Site U1414. The results of our study concern a primary task of IODP Expedition 344 to evaluate fluid/rock interaction linked with the tectonic evolution of the incoming Cocos Plate from the Early Miocene up to recent times. Aqueous, low saline fluids are concentrated within veins from both the Cocos Ridge basalt and the overlying lithified sediments of Unit III. Mineralization and crosscutting relationships give constraints for different vein generations. Isochores from primary, reequilibrated, and secondary fluid inclusions crossed with litho/hydrostatic pressures indicate an anticlockwise PT evolution during vein precipitation and modification by isobaric heating and subsequent cooling at pressures between ˜210 and 350 bar. Internal over and underpressures in the inclusions enabled decrepitation and reequilibration of early inclusions but also modification of vein generations in the Cocos Ridge basalt and in the lithified sediments. We propose that lithification of the sediments was accompanied with a first stage of vein development (VU1 and VC1) that resulted from Galapagos hotspot activity in the Middle Miocene. Heat advection, either related to the Cocos-Nazca spreading center or to hotspot activity closer to the Middle America Trench, led to subsequent vein modification (VC2, VU2/3) related to isobaric heating. The latest mineralization (VC3, VU3) within aragonite and calcite veins and some vesicles of the Cocos Ridge basalt occurred during crustal cooling up to recent times. Fluid inclusion analyses and published isotope data show evidence for communication with deeper sourced, high-temperature hydrothermal fluids within the Cocos Plate. The fluid source of the hydrothermal veins reflects aqueous low saline pore water mixed with invaded seawater.

  16. Fluid inclusion petrology and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414

    PubMed Central

    Brandstätter, Jennifer; Krenn, Kurt; Micheuz, Peter

    2016-01-01

    Abstract In this study, we present new data from microthermometry of fluid inclusions entrapped in hydrothermal veins along the Cocos Ridge from the IODP Expedition 344 Site U1414. The results of our study concern a primary task of IODP Expedition 344 to evaluate fluid/rock interaction linked with the tectonic evolution of the incoming Cocos Plate from the Early Miocene up to recent times. Aqueous, low saline fluids are concentrated within veins from both the Cocos Ridge basalt and the overlying lithified sediments of Unit III. Mineralization and crosscutting relationships give constraints for different vein generations. Isochores from primary, reequilibrated, and secondary fluid inclusions crossed with litho/hydrostatic pressures indicate an anticlockwise PT evolution during vein precipitation and modification by isobaric heating and subsequent cooling at pressures between ∼210 and 350 bar. Internal over and underpressures in the inclusions enabled decrepitation and reequilibration of early inclusions but also modification of vein generations in the Cocos Ridge basalt and in the lithified sediments. We propose that lithification of the sediments was accompanied with a first stage of vein development (VU1 and VC1) that resulted from Galapagos hotspot activity in the Middle Miocene. Heat advection, either related to the Cocos‐Nazca spreading center or to hotspot activity closer to the Middle America Trench, led to subsequent vein modification (VC2, VU2/3) related to isobaric heating. The latest mineralization (VC3, VU3) within aragonite and calcite veins and some vesicles of the Cocos Ridge basalt occurred during crustal cooling up to recent times. Fluid inclusion analyses and published isotope data show evidence for communication with deeper sourced, high‐temperature hydrothermal fluids within the Cocos Plate. The fluid source of the hydrothermal veins reflects aqueous low saline pore water mixed with invaded seawater. PMID:27570496

  17. Fault valve action and vein development during strike slip faulting: An example from the Ribeira Shear Zone, Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Faleiros, Frederico Meira; Campanha, Ginaldo Ademar da Cruz; Bello, Rosa Maria da Silveira; Fuzikawa, Kazuo

    2007-06-01

    Fluid inclusion microthermometry and structural data are presented for quartz vein systems of a major dextral transcurrent shear zone of Neoproterozoic-Cambrian age in the Ribeira River Valley area, southeastern Brazil. Geometric and microstructural constraints indicate that foliation-parallel and extensional veins were formed during dextral strike-slip faulting. Both vein systems are formed essentially by quartz and lesser contents of sulfides and carbonates, and were crystallized in the presence of CO 2-CH 4 and H 2O-CO 2-CH 4-NaCl immiscible fluids following unmixing from a homogeneous parental fluid. Contrasting fluid entrapment conditions indicate that the two vein systems were formed in different structural levels. Foliation-parallel veins were precipitated beneath the seismogenic zone under pressure fluctuating from moderately sublithostatic to moderately subhydrostatic values (319-397 °C and 47-215 MPa), which is compatible with predicted fluid pressure cycle curves derived from fault-valve action. Growth of extensional veins occurred in shallower structural levels, under pressure fluctuating from near hydrostatic to moderately subhydrostatic values (207-218 °C and 18-74 MPa), which indicate that precipitation occurred within the near surface hydrostatically pressured seismogenic zone. Fluid immiscibility and precipitation of quartz in foliation-parallel veins resulted from fluid pressure drop immediately after earthquake rupture. Fluid immiscibility following a local pressure drop during extensional veining occurred in pre-seismic stages in response to the development of fracture porosity in the dilatant zone. Late stages of fluid circulation within the fault zone are represented dominantly by low to high salinity (0.2 to 44 wt.% equivalent NaCl) H 2O-NaCl-CaCl 2 fluid inclusions trapped in healed fractures mainly in foliation-parallel veins, which also exhibit subordinate H 2O-NaCl-CaCl 2, CO 2-(CH 4) and H 2O-CO 2-(CH 4)-NaCl fluid inclusions trapped

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Quartz structure transformation under a shock wave

    NASA Astrophysics Data System (ADS)

    Vettegren', V. I.; Kuksenko, V. S.; Shcherbakov, I. P.; Mamalimov, R. I.

    2015-12-01

    The structure of a fragment formed after quartz single-crystal fracture under a shock wave has been studied using the Fourier transform infrared spectroscopy (FTIR) method. The wave is initiated by electrical breakdown of air in a hole within the single crystal. It has been found that a layer ~0.15 μm thick consisting of "diaplectic glass," i.e., quartz with a strongly distorted lattice, is formed on the fragment surface. A layer 2 μm thick with a compressed quartz lattice is located under it.

  20. An experimental study of the diffusion of oxygen in quartz and albite using an overgrowth technique

    NASA Astrophysics Data System (ADS)

    Elphick, S. C.; Dennis, P. F.; Graham, C. M.

    1986-09-01

    Diffusion rates of18O tracer in quartz (∥ c, 1 Kb H2O) and Amelia albite (⊥ 001, 2 Kb H2O) have been measured, using Secondary Ion Mass Spectrometry (SIMS). A new technique involving hydrothermal deposition of labelled materials has removed the possibility of pressure solution-reprecipitation processes adversely affecting the experiments. Reported diffusion constants are: β-quartz (∥ c),D_0 = 3.4left( {begin{array}{*{20}c} { + 4.8} \\ { - 2.0} \\ } right)x 10^{ - {text{13}}} {text{m}}^{text{2}} {text{s}}^{ - {text{1}}} , Q=98±7 KJ mol-1 (600 825° C, 1 Kb); Amelia albite (⊥ 001),D_0 = 1.0left( {begin{array}{*{20}c} { + 2.0} \\ { - 0.7} \\ } right)x 10^{ - {text{13}}} {text{m}}^{text{2}} {text{s}}^{ - {text{1}}} , Q=85±7 KJ mol-1, (400 600° C, 2 Kb). Measured quartz18O diffusivities decrease discontinuously at the α- β transition, reflecting strong structural influences. The reported albite data agree with previously recorded studies, but β-quartz data indicate significantly lower activation energies. Possible causes of this discrepancy, and some geological consequences, are noted.

  1. Frictional strengths of talc-serpentine and talc-quartz mixtures

    USGS Publications Warehouse

    Moore, Diane E.; Lockner, D.A.

    2011-01-01

    Talc is a constituent of faults in a variety of settings, and it may be an effective weakening agent depending on its abundance and distribution within a fault. We conducted frictional strength experiments under hydrothermal conditions to determine the effect of talc on the strengths of synthetic gouges of lizardite and antigorite serpentinites and of quartz. Small amounts of talc weaken serpentinite gouges substantially more than predicted by simple weight averaging. In comparison, mixtures of quartz and talc show a linear trend of strength reduction at talc concentrations 15 wt % and enhanced weakening at higher concentrations. All of the strength data are fit by a modified version of the Reuss mixing law that allows for the dominance of one mineral over the other. The difference in the behavior of serpentinite-talc and quartz-talc mixtures at low talc concentrations is a reflection of their different textures. Lizardite, antigorite, and talc all have platy habits, and displacement within gouges composed of these minerals is localized to narrow shears along which the platy grains have rotated into alignment with the shear surfaces. The shears in the mixed phyllosilicate gouges maximize the proportion of the weaker mineral within them. When mixed with a strong, rounded mineral such as quartz, some minimum concentration of talc is needed to form connected pathways that enhance strength reductions. The typical development of talc by the reaction of Si-rich fluids with serpentinite or dolomite would tend to localize its occurrence in a natural fault and result in enhanced weakening.

  2. Mixing from below in hydrothermal ore deposits

    NASA Astrophysics Data System (ADS)

    Bons, Paul D.; Gomez-Rivas, Enrique; Markl, Gregor; Walter, Bejamin

    2014-05-01

    Unconformity-related hydrothermal ore deposits typically show indications of mixing of two end-member fluids: (a) hot, deep, rock-buffered basement brines and (b) colder fluids derived from the surface or overlying sediments. The hydromechanics of bringing these fluids together from above and below remain unclear. Classical percolative Darcy-flow models are inconsistent with (1) fluid overpressure indicated by fracturing and brecciation, (2) fast fluid flow indicated by thermal disequilibrium, and (3) strong fluid composition variations on the mm-scale, indicated by fluid inclusion analyses (Bons et al. 2012; Fusswinkel et al. 2013). We propose that fluids first descend, sucked down by desiccation reactions in exhumed basement. Oldest fluids reach greatest depths, where long residence times and elevated temperatures allow them the extensively equilibrate with their host rock, reach high salinity and scavenge metals, if present. Youngest fluids can only penetrate to shallower depths and can (partially) retain signatures from their origin, for example high Cl/Br ratios from the dissolution of evaporitic halite horizons. When fluids are released from all levels of the crustal column, these fluids mix during rapid ascent to form hydrothermal ore deposits. Mixing from below provides a viable hydromechanical mechanism to explain the common phenomenon of mixed shallow and deep fluids in hydrothermal ore deposits. Bons, P.D., Elburg, M.A., Gomez-Rivas, E. 2012. A review of the formation of tectonic veins and their microstructures. J. Struct. Geol. doi:10.1016/j.jsg.2012.07.005 Fusswinkel, T., Wagner, T., Wälle, M., Wenzel, T., Heinrich, C.A., Markl, M. 2013. Fluid mixing forms basement-hosted Pb-Zn deposits: Insight from metal and halogen geochemistry of individual fluid inclusions. Geology. doi:10.1130/G34092.1

  3. High-pressure veins in eclogite from New Caledonia and their significance for fluid migration in subduction zones

    NASA Astrophysics Data System (ADS)

    Spandler, Carl; Hermann, Jörg

    2006-06-01

    This paper describes the petrology and geochemistry of high-pressure veins and associated metasomatic selvages that are hosted by eclogite in the Pouébo Eclogite Melange of northern New Caledonia. Isotopic and geochemical evidence indicates that the mafic host rock represents seafloor-altered fractionated MORB that underwent eclogite-facies metamorphism in a subduction zone. Within the host rock are cm-thick garnet-quartz-phengite veins that are enveloped by garnet-poor, omphacite-rich selvages or bleach zones. Petrography, thermometry, oxygen isotope characteristics, and mass balance calculations are used to show that the veins largely formed by fluid-mediated mass transfer from the bleach zones during prograde metamorphism. Minerals in the veins are free of inclusions, but the vein garnets preserve complex chemical zoning features that are not present in the host rock garnets. Vein garnets have Mn and HREE zoning patterns that are indicative of progressive garnet growth during prograde metamorphism, whereas Mg and Ca contents reveal prominent sector zoning and fine-scale intergrowth features. We propose that the veins formed over a prolonged period during subduction by local circulation of fluid that was sourced from prograde dehydration of minerals in the host rock. Fluid circulation may have been driven by episodic microcracking/sealing around garnet porphyroblasts, which led to significant mass transfer and progressive vein growth. Mass balance calculations and phengite trace element compositions also require the additional of pelite-derived components to the veins. These components were probably introduced into the veins at conditions close to peak metamorphism via a relatively small external fluid flux. This model for vein formation is consistent with previous studies that suggest fluid flow in deeply subducted oceanic crust is highly restricted in many cases. The delay of fluid migration after hydrous mineral breakdown may provide an important source of

  4. Hydrothermal pretreatment of coal

    SciTech Connect

    Loo, Bock; Ross, D.S.

    1990-08-14

    We are examining the effects on composition and behavior of Argonne-supplied Wyodak coal under both thermal (no added water/N{sub 2}) and hydrothermal (liquid water/N{sub 2}) conditions at 350{degree}C for periods of 30 min and 5 hr, with emphasis during this period on the longer treatment. Field ionization mass spectrometry (FIMS) of the untreated, thermally treated, and hydrothermally treated coals is conducted at conditions where the samples are heated from ambient to 500{degree}C at 2.5{degree}/min. In the 5 hr work the volatilities of the coals are 24%, 16%, and 25% respectively. Solvent swelling studies with the recovered coals do not demonstrate the expected lower degree of crosslinking in the hydrothermal case. Both the thermal and hydrothermal treatments yield products with a decreased swelling ratio, but the ratio for the product from the aqueous treatment is slightly lower than that from thermal treatment. At present we cannot reconcile this result with our other data. 4 refs., 6 figs.

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

    PubMed

    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. PMID:25993832

  6. Columbium-, rare-earth-element-, and thorium-bearing veins near Salmon Bay, Southeastern Alaska. Open file report

    SciTech Connect

    Warner, J.D.

    1989-01-01

    In 1984 and 1985 the Bureau of Mines investigated radioactive carbonate veins near Salmon Bay, southeastern Alaska, for concentrations of columbium and associated metals. The veins cut units of graywacke, conglomerate, argillite, and limestone and range in width from less than an inch to greater than 10 ft and have a length ranging from less than a hundred to greater than 1,000 ft. Mineralogy of the veins is complex, and includes thorite, the rare-earth-element minerals monazite, parisite, and bastnaesite, and a columbium mineral that is speculated to be columbite. Gangue minerals include ankerite, dolomite, siderite, quartz and albite. More than seventy veins were sampled but only three contain elevated metal concentrations along a significant strike length. These resources are small compared to columbium, REE, and thorium resources elsewhere in the world.

  7. Vein deposits hosted by plutonic rocks in the Croesus Stock and Hailey gold belt mineralized areas, Blaine County, Idaho

    USGS Publications Warehouse

    Worl, Ronald G.; Lewis, Reed S.

    2001-01-01

    Mineral deposits in the Croesus and Hailey gold belt mineralized areas in Blaine County, south-central Idaho, are preciousand base-metal quartz veins that are part of a family of vein deposits spatially and temporally associated with the Idaho batholith. Historic production from these veins has been mainly gold and silver. Host rocks are older border phase plutons of the Idaho batholith that are characterized by more potassium and less sodium as compared to rocks from the main body of the batholith to the west. Host structures are reverse faults that have moderate to shallow dips to the northeast and high-angle normal faults that also strike northwest. The veins are characterized by several generations of quartz and generally sparse sulfide minerals; gold is associated with late-stage comb quartz. The precious-metal ore bodies are in a series of shoots, each of which is as much as 8 ft in width, 400 ft in breadth, and 1,000 ft in pitch length.

  8. Portal Vein Thrombosis in Cirrhosis

    PubMed Central

    Raja, Kaiser; Jacob, Mathew; Asthana, Sonal

    2013-01-01

    Portal vein thrombosis (PVT) is being increasingly recognized in patients with advanced cirrhosis and in those undergoing liver transplantation. Reduced flow in the portal vein is probably responsible for clotting in the spleno-porto-mesenteric venous system. There is also increasing evidence that hypercoagulability occurs in advanced liver disease and contributes to the risk of PVT. Ultrasound based studies have reported a prevalence of PVT in 10–25% of cirrhotic patients without hepatocellular carcinoma. Partial thrombosis of the portal vein is more common and may not have pathophysiological consequences. However, there is high risk of progression of partial PVT to complete PVT that may cause exacerbation of portal hypertension and progression of liver insufficiency. It is thus, essential to accurately diagnose and stage PVT in patients waiting for transplantation and consider anticoagulation therapy. Therapy with low molecular weight heparin and vitamin K antagonists has been shown to achieve complete and partial recanalization in 33–45% and 15–35% of cases respectively. There are however, no guidelines to help determine the dose and therapeutic efficacy of anticoagulation in patients with cirrhosis. Anticoagulation therapy related bleeding is the most feared complication but it appears that the risk of variceal bleeding is more likely to be dependent on portal pressure rather than solely related to coagulation status. TIPS has also been reported to restore patency of the portal vein. Patients with complete PVT currently do not form an absolute contraindication for liver transplantation. Thrombectomy or thromboendovenectomy is possible in more than 75% of patients followed by anatomical end-to-end portal anastomosis. When patency of the portal vein and/or superior mesenteric vein is not achieved, only non-anatomical techniques (reno-portal anastomosis or cavo-portal hemitransposition) can be performed. These techniques, which do not fully reverse portal

  9. Management of superficial vein thrombosis.

    PubMed

    Cosmi, B

    2015-07-01

    Superficial vein thrombosis (SVT) is less well studied than deep vein thrombosis (DVT), because it has been considered to be a minor, self-limiting disease that is easily diagnosed on clinical grounds and that requires only symptomatic relief. The most frequently involved sites of the superficial vein system are the lower limbs, especially the saphenous veins, mostly in relation to varicosities. Lower-limb SVT shares the same risk factors as DVT; it can propagate into the deep veins, and have a complicated course with pulmonary embolism. Clinical diagnosis may not be accurate, and ultrasonography is currently indicated for both confirmation and evaluation of SVT extension. Treatment aims are symptom relief and prevention of venous thromboembolism (VTE) in relation to the thrombotic burden. SVT of the long saphenous vein within 3 cm of the saphenofemoral junction (SFJ) is considered to be equivalent to a DVT, and thus deserving of therapeutic anticoagulation. Less severe forms of lower-limb SVT not involving the SFJ have been included in randomized clinical trials of surgery, compression hosiery, non-steroidal anti-inflammatory drugs, unfractionated heparin, and low molecular weight heparins, with inconclusive results. The largest randomized clinical trial available, on 3004 patients with lower-limb SVT not involving the SFJ, showed that fondaparinux 2.5 mg once daily for 6 weeks is more effective than placebo in reducing the risk of the composite of death from any cause and symptomatic VTE (0.9% versus 5.9%). Further studies are needed to define the optimal management strategies for SVT of the lower limbs and other sites, such as the upper limbs. PMID:25903684

  10. U-Pb isochron age and Pb isotope systematics of the Golden Fleece vein - implications for the relationship of mineralization to the Lake City caldera, western San Juan Mountains, Colorado.

    USGS Publications Warehouse

    Hon, K.; Ludwig, K. R.; Simmons, K.R.; Slack, J.F.; Grauch, R.I.

    1985-01-01

    A U/Pb isochron age of 27.5 + or - 0.5 m.y. is determined for the Golden Fleece vein, an age which is identical with the age of the quartz latite lavas that the vein cuts. Within the Lake City area, only the Golden Fleece vein contains pitchblende and Au-Ag tellurides and has Pb isotope ratios that together define it as unique within the area. The 27.5 m.y. age relates this vein to the waning stages of the Uncompahgre caldera (27-29) rather than to the Lake City caldera (23.1 m.y.). -G.J.N.

  11. Quartz-Enhanced Photoacoustic Spectroscopy: A Review

    PubMed Central

    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

  12. Quartz Mountain/Oklahoma Summer Arts Institute.

    ERIC Educational Resources Information Center

    Frates, Mary Y.; Madeja, Stanley S.

    1982-01-01

    Describes the Quartz Mountain Oklahoma Summer Arts Institute program. It is designed to nurture artistic talent and to provide intensive arts experiences in music, dance, theater, and the visual arts for talented students aged 14-18. (AM)

  13. Quartz crystal microbalance use in biological studies

    NASA Technical Reports Server (NTRS)

    Green, R. H.; Godfrey, J. F.; Laue, E. G.; Laue, T. M.; Paik, W. W.; Wardle, M. D.

    1972-01-01

    Design, development, and applications of quartz crystal microbalance are discussed. Two types of crystals are used. One serves as reference and other senses changes in mass. Specific application to study of bacterial spores is described.

  14. Fluid inclusions in quartz crystals from South-West Africa

    USGS Publications Warehouse

    Kvenvolden, K.A.; Roedder, E.

    1971-01-01

    Quartz crystals from calcite veins of unknown age in Precambrian metasedimentary rocks at Geiaus No. 6 and Aukam farms in South-West Africa contain both primary and secondary inclusions filled with one or a variable combination of: organic liquid, moderately saline aqueous liquid, dark-colored solid, and vapor. Analysis of these materials by microscopy and by gas chromatography and mass spectrometry shows the presence of constituents of both low and high molecular weights. The former include CH4, C2H6, C3H8 and possibly C4H10 as well as CO, CO2, H2O, N2 and H2. High molecular weight components are dominantly n-alkanes and isoprenoid hydrocarbons. The n-alkanes range from at least n-C10 to n-C33. Concentrations of n-alkanes larger than n-C17 decrease regularly with increasing carbon number. An homologous series of isoprenoid hydrocarbons ranging from at least C14 to C20 is present in unusually high concentrations. Pristane (C19) is most abundant, and C17 isoprenoid is least abundant. The molecular composition and distribution of hydrocarbons suggest biological precursors for these components. Consideration of data provided by freezing, crushing and heating experiments suggests that the pressures at the time these in part supercritical fluids were trapped probably exceeded 30-40 atm, and the minimum trapping temperature was about 120-160??C. Both primary and secondary inclusions apparently containing only organic materials were trapped by the growth of the host quartz from aqueous solution. The data obtained neither prove nor preclude Precambrian, Paleozoic or younger sources for the organic materials. ?? 1971.

  15. Quartz resonator fluid monitors for vehicle applications

    SciTech Connect

    Cernosek, R.W.; Martin, S.J.; Wessendorf, K.O.; Terry, M.D.; Rumpf, A.N.

    1994-09-01

    Thickness shear mode (TSM) quartz resonators operating in a new {open_quotes}Lever oscillator{close_quotes} circuit are used as monitors for critical automotive fluids. These monitors respond to the density and viscosity of liquids contacting the quartz surface. Sensors have been developed for determining the viscosity characteristics of engine lubricating oil, the state-of-charge of lead-acid storage batteries, and the concentration variations in engine coolant.

  16. Quartz resonator fluid monitors for vehicle applications

    NASA Astrophysics Data System (ADS)

    Cernosek, R. W.; Martin, S. J.; Wessendorf, K. O.; Terry, M. D.; Rumpf, A. N.

    Thickness shear mode (TSM) quartz resonators operating in a new 'Lever oscillator' circuit are used as monitors for critical automotive fluids. These monitors respond to the density and viscosity of liquids contacting the quartz surface. Sensors have been developed for determining the viscosity characteristics of engine lubricating oil, the state-of-charge of lead-acid storage batteries, and the concentration variations in engine coolant.

  17. New hole centers in natural quartz

    NASA Astrophysics Data System (ADS)

    Maschmeyer, D.; Lehmann, G.

    1983-11-01

    In natural citrines five new hole centers were detected and analyzed by electron paramagnetic resonance. An additional one was observed in rose-colored quartz crystals with radiation defects as the cause of coloration. Characteristic hyperfine patterns due to an adjacent aluminum impurity were resolved in the spectra of three of these centers. Their relations to other hole centers of well-known structure in quartz and fused silica are discussed and possible models for their structures are proposed.

  18. Method of making a quartz resonator

    DOEpatents

    Vig, John R.; Filler, Raymond L.; Peters, R. Donald; Frank, James M.

    1981-01-01

    A quartz resonator is made from a chemically polished quartz plate. The plate is placed in an enclosure fitted with at least three mounting clips to receive the plate. The plate is secured to the clips with an electrically conductive adhesive capable of withstanding operation at 350 degrees C. The assembly is cleaned and a metallic electrode deposited onto the plate until the desired frequency is reached. The enclosure is then hermetically sealed. The resulting resonator can consistently withstand extremely high shocks.

  19. Hydrothermal synthesis as a route to mineralogically-inspired structures.

    PubMed

    McMillen, Colin D; Kolis, Joseph W

    2016-02-21

    The use of high temperature hydrothermal reactions to prepare crystals having mineralogically-related structures is described. Complex naturally occurring minerals can have fascinating structures and exhibit important features like low dimensionality, noncentrosymmetry, or ion channels that can provide excellent guideposts for the designed synthesis of new materials. Actual minerals, even though they may have intriguing physical properties, are often unsuitable for study because of the persistent impurities inevitably present in natural samples. Hydrothermal fluids at relatively high temperatures provide access to large, high quality single crystals of structures with mineral-like structures. This enables the study of physical properties like ionic conduction, magnetic spin frustration and non-linear optical behavior. Some fundamental considerations of the hydrothermal technique are discussed in the context of synthesizing mineralogically-inspired materials. The metal vanadates provide a surprisingly rich and diversified range of compounds and are selected to illustrate many of the concepts described here. A series of low dimensional mineral analogs featuring isolated units, chains, and layers have been prepared in the laboratory as large single crystals using a high temperature hydrothermal synthetic methods, and their physical properties are under investigation. The metal silicates are also highlighted as another promising field of exploration, since their hydrothermal synthesis surprisingly lags behind the enormous literature of the natural silicate minerals. The introduction of heteroelements, such as boron to make borosilicates, appears to also open the door to additional new materials. Many of these new materials have direct equivalents in the mineral kingdom, while others have no known analogs but are reminiscent of minerals and can be classified in the same ways. From these initial results there appears to be a very rich vein of synthetic minerals waiting

  20. Hydrothermal vents in Lake Tanganyika, East African, Rift system

    NASA Astrophysics Data System (ADS)

    Tiercelin, Jean-Jacques; Pflumio, Catherine; Castrec, Maryse; Boulégue, Jacques; Gente, Pascal; Rolet, Joël; Coussement, Christophe; Stetter, Karl O.; Huber, Robert; Buku, Sony; Mifundu, Wafula

    1993-06-01

    Sublacustrine hydrothermal vents with associated massive sulfides were discovered during April 1987 at Pemba and Cape Banza on the Zaire side of the northern basin of Lake Tanganyika, East African Rift system. New investigations by a team of ten scuba divers during the multinational (France, Zaire, Germany, and Burundi) TANGANYDRO expedition (August-October 1991) found hydrothermal vents down to a depth of 46 m along north-trending active faults bounding the Tanganyika rift on the western side. Temperatures from 53 to 103 °C were measured in hydrothermal fluids and sediments. Veins of massive sulfides 1-10 cm thick (pyrite and marcasite banding) were found associated with vents at the Pemba site. At Cape Banza,active vents are characterized by 1-70-cm-high aragonite chimneys, and there are microcrystalline pyrite coatings on the walls of hydrothermal pipes. Hydrothermal fluid end members show distinctive compositions at the two sites. The Pemba end member is a NaHCO3-enriched fluid similar to the NaHCO3 thermal fluids from lakes Magadi and Bogoria in the eastern branch off the rift. The Cape Banza end member is a solution enriched in NaCl. Such brines may have a deep-seated basement origin, as do the Uvinza NaCl brines on the eastern flank of the Tanganyika basin. Geothermometric calculations have yielded temperatures of fluid-rock interaction off 219 and 179 °C in the Pemba and Cape Banza systems, respectively. Abundant white or reddish-brown microbial colonies resembling Beggiatoa mats were found surrounding the active vents. Thermal fluid circulation is permitted by opening of cracks related to 130 °N normal-dextral faults that intersect the north- south major rift trend. The source of heat for such hydrothermal systems may relate to the existence of magmatic bodies under the rift, which is suggested by the isotopic composition of carbon dioxide released at Pemba and Cape Banza.

  1. Hydrothermal Alteration in the PACMANUS Hydrothermal Field: Implications From Secondary Mineral Assemblages and Mineral Chemistry, OPD Leg 193

    NASA Astrophysics Data System (ADS)

    Lackschewitz, K. S.; Kummetz, M.; Kummetz, M.; Ackermand, D.; Botz, R.; Devey, C. W.; Singer, A.; Stoffers, P.

    2001-12-01

    Leg 193 of the Ocean Drilling Program investigated the subsurface nature of the active PACMANUS hydrothermal field in the Manus backarc basin near Papua New Guinea. Drilling in different areas on the felsic neovolcanic Pual Ridge, including the high-temperature black smoker complex of Roman Ruins and the low-temperature Snowcap site with diffusive discharge yielded a complex alteration history with a regional primary alteration being overprinted by a secondary mineralogy. The intense hydrothermal alteration at both sites shows significant differences in the secondary mineralogy. At Roman Ruins, the upper 25 m of hydrothermally altered rocks are characterized by a rapid change from secondary cristobalite to quartz, implying a high temperature gradient. From 10 to 120 mbsf the clay mineralogy is dominated by illite and chlorite. The chlorite formation temperature calculated from oxygen isotope data lies at 250° C in 116 mbsf which is similar to the present fluid outflow temperatures of 240-250° C (Douville et al., 1999, Geochim. Cosmochim. Acta, 63, 627-643). Drilling in the Snowcap field recovered evidence for several stages of hydrothermal alteration. Between 50 and 150 mbsf, cristobalite and chlorite are the most abundant alteration minerals while hydrothermal pyrophyllite becomes abundant in some places At 67 mbsf, the isotopic composition of pyrophyllite gives a temperature for ist formation at 260° C whereas at 77 and 116 mbsf the pyrophyllite displays the highest temperatures of formation (>300° C). These temperatures are close to the maximum measured borehole temperatures of 313° C. The appearance of assemblages of chlorite, chlorite-vermiculite, chlorite-vermiculite-smectite and illite-smectite as well as the local development of corrensite below 150 mbsf suggests that the alteration at Snowcap may be more complex than that beneath Roman Ruins. Detailed geochemical studies of the authigenic clay mineral phases will provide further insights into the

  2. ESR studies on bleached sedimentary quartz

    NASA Astrophysics Data System (ADS)

    Walther, R.; Zilles, D.

    Some ESR signals in quartz are reported to be bleachable by sunlight and so they promise to be useful for dating sediments (Grün, 1989). The Ge signal in quartz is the only one that shows bleaching effects with UV light in short time scales (hours). Therefore we used quartz samples from the sites of Mauer ( 'Homo erectus heidelbergensis'), samples from a borehole in the Neckar valley ('Entensee', Ladenburg near Heidelberg) and samples from a pegmatite for basic studies on the Ge signal. The results show that with our standard sample preparation procedure for quartz separation (using red light as for TL samples), the natural Ge signal is not detectable, but rises clearly with gamma irradiation. Several experiments for examination of the stability and sensitivity of the Ge centre in quartz were carried out. For comparison with the behaviour of the Ge signal we measured the Al signal as well. Our experiments show that the Al signal is bleachable in long time scales (weeks). The behaviour on bleaching, irradiation and thermal annealing is very complicated, as the Al centre is a hole centre (it possibly interacts with several electron centres in the quartz and so the processes are of higher order).

  3. Hydrothermal alteration maps of the central and southern Basin and Range province of the United States compiled from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data

    USGS Publications Warehouse

    Mars, John L.

    2013-01-01

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and Interactive Data Language (IDL) logical operator algorithms were used to map hydrothermally altered rocks in the central and southern parts of the Basin and Range province of the United States. The hydrothermally altered rocks mapped in this study include (1) hydrothermal silica-rich rocks (hydrous quartz, chalcedony, opal, and amorphous silica), (2) propylitic rocks (calcite-dolomite and epidote-chlorite mapped as separate mineral groups), (3) argillic rocks (alunite-pyrophyllite-kaolinite), and (4) phyllic rocks (sericite-muscovite). A series of hydrothermal alteration maps, which identify the potential locations of hydrothermal silica-rich, propylitic, argillic, and phyllic rocks on Landsat Thematic Mapper (TM) band 7 orthorectified images, and geographic information systems shape files of hydrothermal alteration units are provided in this study.

  4. Significance of geometrical relationships between low-temperature intracrystalline deformation microstructures in naturally deformed quartz

    NASA Astrophysics Data System (ADS)

    Derez, T.; Pennock, G.; Drury, M. R.; Sintubin, M.

    2013-12-01

    Although quartz is one of the most studied minerals in the Earth's crust when it comes to its rheology, the interpretation of intracrystalline deformation microstructures with respect to deformation conditions and mechanisms, remains highly contentious. Moreover, inconsistent use of terminology for both deformation microstructures and mechanisms makes a correct assessment of observations and interpretations in published material very difficult. With respect to low-temperature intracrystalline deformation microstructures in quartz, different conflicting genetic models have been proposed. Most probably, the lack of consensus means that there is no unique interpretation for these microstructures, primarily because their initiation and development depend on many ambient conditions. We extensively studied these intracrystalline deformation microstructures by means of optical microscopy, Hot-Cathodoluminescence, SEM-Cathodoluminescence and Electron Backscatter Diffraction Orientation Imaging, in vein quartz of the High-Ardenne slate belt (Belgium, France, Luxemburg, Germany), (de)formed in a low-temperature regime. Firstly, we propose a new, purely descriptive terminology for the low-temperature intracrystalline deformation microstructures in naturally deformed quartz: fine extinction bands (FEB), wide extinction bands (WEB) and strings. The strings can be further subdivided into blocky (BS), straight (SS) and recrystallised (RS) morphological types. FEBs have consistently been called deformation lamellae in quartz and planar slip bands in metals. WEBs have been called deformation bands, prismatic kink bands or type II kink bands. Strings have formerly been called shear bands, deformation bands or type I kink bands. No distinction between blocky and straight morphological string types had ever been made. Secondly, a survey of the pre-recrystallisation stages in the history of the intracrystalline deformation microstructures reveals that the different types of low

  5. Blackberry Yellow Vein Disease Complex

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new virus disease has emerged in the Midsouth and Southeastern United States and was named blackberry yellow vein disease (BYVD). Originally, it was thought the disease was caused by Tobacco ringspot virus (TRSV) as the virus was found in many diseased plants and symptoms were very similar to thos...

  6. The Treatment of Varicose Veins

    PubMed Central

    Subramonia, S; Lees, TA

    2007-01-01

    INTRODUCTION Over the past few years, there has been a move to less invasive endoluminal methods in the treatment of lower limb varicose veins combined with a renewed interest in sclerotherapy, with the recent addition of foam sclerotherapy. The development of these new techniques has led many to question some of the more conventional teaching on the treatment of varicose veins. This review examines these new treatments for lower limb varicose veins and the current evidence for their use. MATERIALS AND METHODS An extensive search of available electronic and paper-based databases was performed to identify studies relevant to the treatment of varicose veins with particular emphasis on those published within the last 10 years. These were analysed by both reviewers independently. RESULTS There is no single method of treatment appropriate for all cases. Conventional surgery is safe and effective and is still widely practised. Whilst the new treatments may be popular with both surgeons and patients, it is important that they are carefully evaluated not only for their clinical benefits and complications when compared to existing treatments but also for their cost prior to their wider acceptance into clinical practice. PMID:17346396

  7. Diagnosis of deep vein thrombosis.

    PubMed Central

    Douketis, J. D.; Ginsberg, J. S.

    1996-01-01

    Deep vein thrombosis (DVT), a common disease, can be difficult to diagnose because its clinical features are nonspecific. Venography is the standard test, but other less expensive, easily performed, noninvasive tests are available. At present, duplex ultrasonography is the noninvasive test of choice. PMID:8616289

  8. Varicose veins - what to ask your doctor

    MedlinePlus

    ... Below are some questions you may want to ask your health care provider to help you take ... What to ask your doctor about varicose veins; Venous insufficiency - what to ask your doctor; Vein stripping - what to ask your ...

  9. A demonstration of an affinity between pyrite and organic matter in a hydrothermal setting

    PubMed Central

    2011-01-01

    One of the key-principles of the iron-sulphur world theory is to bring organic molecules close enough to interact with each other, using the surface of pyrite as a substrate in a hydrothermal setting. The present paper explores the relationship of pyrite and organic matter in a hydrothermal setting from the geological record; in hydrothermal calcite veins from Carboniferous limestones in central Ireland. Here, the organic matter is accumulated as coatings around, and through, pyrite grains. Most of the pyrite grains are euhedral-subhedral crystals, ranging in size from ca 0.1-0.5 mm in diameter, and they are scattered throughout the matrix of the vein calcite. The organic matter was deposited from a hydrothermal fluid at a temperature of at least 200°C, and gives a Raman signature of disordered carbon. This study points to an example from a hydrothermal setting in the geological record, demonstrating that pyrite can have a high potential for the concentration and accumulation of organic materials. PMID:21299877

  10. Quartz Microstructures in Rocks From the Rochechouart Impact Structure, France - High Stress Deformation and Subsequent Annealing

    NASA Astrophysics Data System (ADS)

    Trepmann, C. A.

    2006-12-01

    Quartz microstructures in impact breccias and target rocks from the Rochechouart impact structure, as well as rocks not affected by shock, outside the structure, are compared. Suevites and impact breccias contain clasts of shocked quartz that show planar fractures (PFs), planar deformation features (PDFs) and mosaicism, as revealed by transmission electron microscopy (TEM). PDFs comprise fluid inclusions and dislocations aligned in narrow strings mostly parallel to the π and ω rhombohedra of quartz. The spacing between PDFs is typically <0.5 μm. Multiple PDF sets intersect each other. Dislocation walls separate cells in the interspace between PDFs. Mosaicism is characterized by tiny cells (<0.5 μm in diameter) that are markedly misoriented, as indicated by streaky diffraction spots. Planar features occur, along which the cells are aligned, probably representing remnants of PDFs. These characteristics imply high shock pressures on the order of 20 GPa during shock. The microstructure apparent in the TEM indicates post-shock recovery and recrystallisation at probably quasi-static conditions. Shocked quartz in autochthonous gneisses at ~5 km NE of the assumed centre of the structure show few PDFs parallel to the ω rhombohedra and/or basal PDFs, which represent mechanical Brazil twins. In general, PDF density is lower in shocked quartz from authochthonous target rocks compared to shocked quartz from impact breccias. These characteristics imply that the target rocks are affected by shock pressures on the order of 8 GPa. In most gneisses no cataclastic deformation is recorded by the microfabric. In autochthonous recrystallized vein quartz, however, cataclastic zones show a shear offset of up to 0.5 mm and comprise small cataclasites with an average diameter of 7±4 μm. Quartz containing basal PDFs is restricted to these cataclastic zones. Rhombohedral PDFs do not occur. These characteristics imply low shock pressures and a high shock-induced differential stress. In

  11. Hydrothermal mineralising systems as critical systems

    NASA Astrophysics Data System (ADS)

    Hobbs, Bruce

    2015-04-01

    Hydrothermal mineralising systems as critical systems. Bruce E Hobbs1,2, Alison Ord1 and Mark A. Munro1. 1. Centre for Exploration Targeting, The University of Western Australia, M006, 35 Stirling Highway, Crawley, WA 6009, Australia. 2. CSIRO Earth and Resource Engineering, Bentley, WA, Australia Hydrothermal mineralising systems are presented as large, open chemical reactors held far from equilibrium during their life-time by the influx of heat, fluid and dissolved chemical species. As such they are nonlinear dynamical systems and need to be analysed using the tools that have been developed for such systems. Hydrothermal systems undergo a number of transitions during their evolution and this paper focuses on methods for characterising these transitions in a quantitative manner and establishing whether they resemble first or second (critical) phase transitions or whether they have some other kind of nature. Critical phase transitions are characterised by long range correlations for some parameter characteristic of the system, power-law probability distributions so that there is no characteristic length scale and a high sensitivity to perturbations; as one approaches criticality, characteristic parameters for the system scale in a power law manner with distance from the critical point. The transitions undergone in mineralised hydrothermal systems are: (i) widespread, non-localised mineral alteration involving exothermic mineral reactions that produce hydrous silicate phases, carbonates and iron-oxides, (ii) strongly localised veining, brecciation and/or stock-work formation, (iii) a series of endothermic mineral reactions involving the formation of non-hydrous silicates, sulphides and metals such as gold, (iv) multiple repetitions of transitions (ii) and (iii). We have quantified aspects of these transitions in gold deposits from the Yilgarn craton of Western Australia using wavelet transforms. This technique is convenient and fast. It enables one to establish if

  12. phenoVein-A Tool for Leaf Vein Segmentation and Analysis.

    PubMed

    Bühler, Jonas; Rishmawi, Louai; Pflugfelder, Daniel; Huber, Gregor; Scharr, Hanno; Hülskamp, Martin; Koornneef, Maarten; Schurr, Ulrich; Jahnke, Siegfried

    2015-12-01

    Precise measurements of leaf vein traits are an important aspect of plant phenotyping for ecological and genetic research. Here, we present a powerful and user-friendly image analysis tool named phenoVein. It is dedicated to automated segmenting and analyzing of leaf veins in images acquired with different imaging modalities (microscope, macrophotography, etc.), including options for comfortable manual correction. Advanced image filtering emphasizes veins from the background and compensates for local brightness inhomogeneities. The most important traits being calculated are total vein length, vein density, piecewise vein lengths and widths, areole area, and skeleton graph statistics, like the number of branching or ending points. For the determination of vein widths, a model-based vein edge estimation approach has been implemented. Validation was performed for the measurement of vein length, vein width, and vein density of Arabidopsis (Arabidopsis thaliana), proving the reliability of phenoVein. We demonstrate the power of phenoVein on a set of previously described vein structure mutants of Arabidopsis (hemivenata, ondulata3, and asymmetric leaves2-101) compared with wild-type accessions Columbia-0 and Landsberg erecta-0. phenoVein is freely available as open-source software. PMID:26468519

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

    SciTech Connect

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

    2008-07-15

    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.

  14. Mesozoic hydrothermal alteration associated with gold mineralization in the Mercur district, Utah

    SciTech Connect

    Wilson, P.N.; Parry, W.T. )

    1990-09-01

    K/Ar dates and chemical data show that a Mesozoic gold-bearing hydrothermal system altered black shales of the Mississippian Great Blue Limestone throughout an area encompassing the Mercur gold district, Utah. K/Ar dates of illite veins and illite-rich, clay-sized separates of altered shales that are enriched in Au, As, Hg, Sc, and other heavy metals indicate that hydrothermal activity occurred from 193 to 122 Ma. Several ages from within the Mercur district cluster near 160 Ma and may date the minimum age of gold mineralization.

  15. Tectonophysics of hydrothermal ore formation: an example of the Antei Mo-U deposit, Transbaikalia

    NASA Astrophysics Data System (ADS)

    Petrov, V. A.; Rebetsky, Yu. L.; Poluektov, V. V.; Burmistrov, A. A.

    2015-07-01

    The Antei deposit of the southeastern Transbaikalian region is one of the largest uranium mines in Russia. It is hosted by the Late Paleozoic granitic basement of the Streltsovskaya caldera and was formed as a result of Late Mesozoic tectonothermal activity. Vein and stockwork-disseminated molybdenum-uranium mineralization at this deposit is controlled by zones of intense hydrothermal alteration, cataclasis, brecciation, and intense fracturing along steeply dipping faults, which acted as conduits for mineralizing fluids and hosts to the ore bodies. The upper edge of the ore-bearing zone is located at a depth of 400 m, and its lower edge was intersected at a depth of 1300 m from the day surface. The conditions of ore localization were determined using structural-geological and petrophysical studies coupled with numerical modeling of the effects of gravitational body forces at purely elastic and postcritical elastoplastic deformational stages. The dynamics of the tectonic stress field in the rock massif was reconstructed using the results of mapping of morphogenetic and kinematic characteristics of fault and fracture systems, as well as data on petrography and mineralogy of rocks and vein-filling material. It was shown that the fault framework of the deposit was formed in four tectonic stages, three of which took place in the geologic past and one of which reflects recent geologic history. Each tectonic stage was characterized by different parameters of the tectonic stress-strain field, fault kinematics, and conditions of mineral formation. The following types of metasomatic rocks are recognized within the deposit: high-temperature K-feldspar rocks and albitites (formed during the Late Paleozoic as the primary structural elements of a granitic massif) and Late Mesozoic low-temperature preore (hydromicatized rocks), synore (hematite, albite, chlorite, and quartz) and postore (kaolinite-smectite) rocks. The following petrophysical parameters were determined for all

  16. Prediction of long saphenous vein graft adaptation.

    PubMed

    Davies, A H; Magee, T R; Hayward, J K; Baird, R N; Horrocks, M

    1994-07-01

    The ability of vein to dilate may allow smaller veins to be used for bypass if this change could be predicted. Sixty patients undergoing femorodistal popliteal or infrapopliteal bypass have had their long saphenous vein studied. Diameter measurements of the long saphenous vein have been performed using an ATL Duplex scanner at the groin, mid-thigh and knee. Measurements were performed preoperatively both at rest and with a venous occlusion cuff to dilate the vein and subsequently at 7 days and 3, 6, 9, 12 months after implantation. The mean diameter of the vein at the mid thigh was 4.2 mm non dilated, 5.1 mm with occlusion, 5.4 mm 7 days postoperatively and 5.5 mm at 12 months (p < 0.01 ANOVA). The mean diameter of the vein at the knee was 3.8 mm non-dilated, 4.8 mm with occlusion, 4.8 mm at 7 days and 5.0 mm at 12 months after operation (p < 0.01 ANOVA). If the minimum resting internal diameter of vein regarded as being suitable for bypass was 3 mm, this technique would have increased the vein utilisation rate by 22%. These results show that by using a technique of venous occlusion at the time of preoperative vein mapping the adaptive response of the vein can be predicted and this can result in an increased rate of vein utilisation. PMID:8088400

  17. Hydrothermal reactivity of saponite.

    USGS Publications Warehouse

    Whitney, G.

    1983-01-01

    The nature and extent of the reactions of synthetic Fe-free saponite have been investigated under experimental hydrothermal conditions as a first step towards understanding saponite reactivity under relatively simple conditions. Saponite crystallizes from amorphous gel of ideal saponite composition within 7 days at 300o-550oC under P = 1 kbar. Reactions subsequent to this initial crystallization depend on reaction T and interlayer cations. Saponite is found to react hydrothermally, over a period of 200 days, at T down to 400oC, at least 150oC lower than previously reported, but showed no signs of reaction below 400oC. At 450oC, a mixture of talc/saponite and saponite/phlogopite clays forms from K-saponite via intracrystalline layer transformations, while above 450oC the initial K-saponite dissolves, with talc and phlogopite forming as discrete phases. After 200 days reactions at 400-450oC were not complete, so that given sufficient time to reach equilibrium, a lower hydrothermal stability limit for saponite is possible. Further study of the Fe-bearing saponite system will be required before experimental results can be applied to natural systems.-D.F.B.

  18. Environment of ore deposition in the creede mining district, San Juan Mountains, Colorado: Part V. Epithermal mineralization from fluid mixing in the OH vein

    USGS Publications Warehouse

    Hayba, D.O.

    1997-01-01

    Detailed fluid inclusion studies on coarse-grained sphalerite from the OH vein, Creede, Colorado, have shown that the abrupt color changes between growth zones correspond to abrupt changes in the nature of the ore fluids. Within each growth zone, however, the composition of the fluids remained constant. The base of a distinctive orange-brown growth zone marks a sharp increase in both temperature and salinity relative to the preceding yellow-white zone. The orange-brown growth zone can be correlated along much of the vein and is believed to represent a time-stratigraphic interval. Along the vein, temperatures and salinities of fluid inclusions within this interval show a systematic decrease from about 285??C and 11.5 wt percent NaCl equiv near the base of the vein to about 250??C and 8 wt percent NaCl equiv, respectively, near the top of the vein. The iron concentration of this sphalerite growth zone shows a similar pattern, decreasing from about 2.8 to 1.2 mole percent FeS. When plotted on an enthalpy-salinity diagram, the fluid inclusion data define a spatial trend indicating the progressive mixing of deeply circulating hydrothermal brines with overlying, dilute ground waters. The hydrothermal brines entered the OH vein from below at a temperature, salinity, and density of approximately 285??C, 11.5 wt percent NaCl equiv, and 860 kg/m3, respectively, whereas the overlying ground waters appear to have been preheated to roughly 150??C and had an assumed salinity of 0 wt percent and a density of 920 kg/m3. The greater density of the heated ground water promoted mixing with the hydrothermal brine within the open fractures, causing sphalerite deposition. Although there were also episodes of boiling during vein mineralization, boiling appears unimportant for this sphalerite. Isotopic evidence and geochemical modeling studies also indicate that mixing was the depositional mechanism for sphalerite. An important aspect of the mixing hydrology of the Creede system involves

  19. Study of Pellets and Lumps as Raw Materials in Silicon Production from Quartz and Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Dal Martello, E.; Tranell, G.; Gaal, S.; Raaness, O. S.; Tang, K.; Arnberg, L.

    2011-10-01

    The use of high-purity carbon and quartz raw materials reduces the need for comprehensive refining steps after the silicon has been produced carbothermically in the electric reduction furnace. The current work aims at comparing the reaction mechanisms and kinetics occurring in the inner part of the reduction furnace when pellets or lumpy charge is used, as well as the effect of the raw material mix. Laboratory-scale carbothermic reduction experiments have been carried out in an induction furnace. High-purity silicon carbide and two different high-purity hydrothermal quartzes were charged as raw materials at different molar ratios. The charge was in the form of lumps (size, 2-5 mm) or as powder (size, 10-20 μm), mixed and agglomerated as pellets (size, 1-3 mm) and reacted at 2273 K (2000 °C). The thermal properties of the quartzes were measured also by heating a small piece of quartz in CO atmosphere. The investigated quartzes have different reactivity in reducing atmosphere. The carbothermal reduction experiments show differences in the reacted charge between pellets and lumps as charge material. Solid-gas reactions take place from the inside of the pellets porosity, whereas reactions in lumps occur topochemically. Silicon in pellets is produced mainly in the rim zone. Larger volumes of silicon have been found when using lumpy charge. More SiO is produced when using pellets than for lumpy SiO2 for the same molar ratio and heating conditions. The two SiC polytypes used in the carbothermal reduction experiments as carbon reductants presented different reactivity.

  20. Mass transfer and fluid evolution in late-metamorphic veins, Rhenish Massif (Germany): insight from alteration geochemistry and fluid-mineral equilibria modeling

    NASA Astrophysics Data System (ADS)

    Marsala, Achille; Wagner, Thomas

    2016-01-01

    Element mobility and fluid-rock interaction related to the formation of late-metamorphic quartz veins have been studied by combination of mineral chemistry, whole-rock geochemistry, mass balance analysis and fluid-mineral equilibria modeling. The quartz veins are hosted by very low-grade metasedimentary rocks of the fold-and-thrust belt of the Rhenish Massif (Germany). The veins record two stages of evolution, a massive vein filling assemblage with elongate-blocky quartz, chlorite, apatite and albite, and a later open space filling assemblage with euhedral crystals of quartz, ankerite-dolomite and minor calcite and sulfides. Detailed mass balance analysis of an alteration profile adjacent to a representative quartz vein demonstrates that element mobility is restricted to the proximal zone. The most important element changes are gain of Ca, Fe, Mg, Mn, P and CO2, and loss of Si, K and Na. The data demonstrate that wall-rock carbonation is one of the main alteration features, whereas mobility of Si, K and Na are related to dissolution of quartz and destruction of detrital feldspar and muscovite. The whole-rock geochemical data, in conjunction with fluid composition data and pressure-temperature estimates, were used as input for fluid-mineral equilibria modeling in the system Si-Al-Fe-Mg-Ca-Na-K-C-S-O-H-B-F-Cl. Modeling involved calculation of rock-buffered fluid compositions over the temperature interval 100-500 °C, and reaction-path simulations where a rock-buffered high-temperature fluid reacts with fresh host-rocks at temperatures of 400, 300 and 200 °C. Calculated rock-buffered fluid compositions demonstrate that retrograde silica solubility is a strong driving force for quartz leaching in the temperature-pressure window of 380-450 °C and 0.5 kbar. These conditions overlap with the estimated temperatures for the initial stage of vein formation. Reaction-path models show that high-temperature alteration can produce the observed silica leaching, suggesting that

  1. Mass transfer and fluid evolution in late-metamorphic veins, Rhenish Massif (Germany): insight from alteration geochemistry and fluid-mineral equilibria modeling

    NASA Astrophysics Data System (ADS)

    Marsala, Achille; Wagner, Thomas

    2016-08-01

    Element mobility and fluid-rock interaction related to the formation of late-metamorphic quartz veins have been studied by combination of mineral chemistry, whole-rock geochemistry, mass balance analysis and fluid-mineral equilibria modeling. The quartz veins are hosted by very low-grade metasedimentary rocks of the fold-and-thrust belt of the Rhenish Massif (Germany). The veins record two stages of evolution, a massive vein filling assemblage with elongate-blocky quartz, chlorite, apatite and albite, and a later open space filling assemblage with euhedral crystals of quartz, ankerite-dolomite and minor calcite and sulfides. Detailed mass balance analysis of an alteration profile adjacent to a representative quartz vein demonstrates that element mobility is restricted to the proximal zone. The most important element changes are gain of Ca, Fe, Mg, Mn, P and CO2, and loss of Si, K and Na. The data demonstrate that wall-rock carbonation is one of the main alteration features, whereas mobility of Si, K and Na are related to dissolution of quartz and destruction of detrital feldspar and muscovite. The whole-rock geochemical data, in conjunction with fluid composition data and pressure-temperature estimates, were used as input for fluid-mineral equilibria modeling in the system Si-Al-Fe-Mg-Ca-Na-K-C-S-O-H-B-F-Cl. Modeling involved calculation of rock-buffered fluid compositions over the temperature interval 100-500 °C, and reaction-path simulations where a rock-buffered high-temperature fluid reacts with fresh host-rocks at temperatures of 400, 300 and 200 °C. Calculated rock-buffered fluid compositions demonstrate that retrograde silica solubility is a strong driving force for quartz leaching in the temperature-pressure window of 380-450 °C and 0.5 kbar. These conditions overlap with the estimated temperatures for the initial stage of vein formation. Reaction-path models show that high-temperature alteration can produce the observed silica leaching, suggesting that

  2. Cathodoluminescence investigations on quartz cement in the sandstones of Khabour Formation from Iraqi Kurdistan Region, Northern Iraq

    NASA Astrophysics Data System (ADS)

    Omer, Muhamed F.; Friis, Henrik

    2014-03-01

    The Ordovician deltaic to shallow marine Khabour Formation in Northern Iraq consists mainly of sandstone with minor siltstone and interbedded shale. The sandstones are pervasively cemented by quartz that resulted in very little preserved primary porosity. Cathodoluminescence and petrographic studies showed that the silica cementation occurred in five successive phases which can be distinguished by their luminescence pattern. The precipitations of two phases have predated the major compaction process while the other phases are younger. The successive phases represent a sequence of changes in silica supply which were classified as very early and early, derived from dissolved biogenic silica that precipitated as opal/microquartz, possibly pre-compactional and of non-luminescent quartz overgrowth type. This was followed by phases whose silica supply derived from pressure solution of quartz, dissolution of feldspar, and hydrothermal fluids related to major thrust fault event. These successive quartz cement phases showed an increase in luminescence and the development of complicated zonation pattern in late-stage quartz cementation.

  3. Mechanisms of Mg-phyllosilicate formation in a hydrothermal system at a sedimented ridge (Middle Valley, Juan de Fuca)

    NASA Astrophysics Data System (ADS)

    Buatier, M. D.; Früh-Green, Gretchen L.; Karpoff, A. M.

    1995-11-01

    We present results of a detailed mineralogical and geochemical study of the progressive hydrothermal alteration of clastic sediments recovered at ODP Site 858 in an area of active hydrothermal venting at the sedimented, axial rift valley of Middle Valley (northern Juan de Fuca Ridge). These results allow a characterization of newly formed phyllosilicates and provide constraints on the mechanisms of clay formation and controls of mineral reactions on the chemical and isotopic composition of hydrothermal fluids. Hydrothermal alteration at Site 858 is characterized by a progressive change in phyllosilicate assemblages with depth. In the immediate vent area, at Hole 858B, detrital layers are intercalated with pure hydrothermal precipitates at the top of the section, with a predominance of hydrothermal phases at depth. Sequentially downhole in Hole 858B, the clay fraction of the pure hydrothermal layers changes from smectite to corrensite to swelling chlorite and finally to chlorite. In three pure hydrothermal layers in the deepest part of Hole 858B, the clay minerals coexist with neoformed quartz. Neoformed and detrital components are clearly distinguished on the basis of morphology, as seen by SEM and TEM, and by their chemical and stable isotope compositions. Corrensite is characterized by a 24 Å stacking sequence and high Si- and Mg-contents, with Fe/(Fe+Mg) ratio of ≈0.08. We propose that corrensite is a unique, possibly metastable, mineralogical phase and was precipitated directly from seawater-dominated hydrothermal fluids. Hydrothermal chlorite in Hole 858B has a stacking sequence of 14 Å with Fe/(Fe+Mg) ratios of ≈0.35. The chemistry and structure of swelling chlorite suggest that it is a corrensite/chlorite mixed-layer phase. The mineralogical zonation in Hole 858B is accompanied by a systematic decrease in δ18O, reflecting both the high thermal gradients that prevail at Site 858 and extensive sediment-fluid interaction. Precipitation of the Mg

  4. AMS as a technique for investigating the propagation direction of vein fluids

    NASA Astrophysics Data System (ADS)

    Watts, Colin; McCarthy, William

    2016-04-01

    An approximately co-planar relationship between mineral orientations and magnetic fabric has been frequently employed when studying petrofabrics, most notably planar silicates in mafic intrusives. In this study this relationship is exploited with respect to mineralising veins, using anisotropy of magnetic susceptibility (AMS) to investigate whether magnetic fabrics could reveal the direction of fluid propagation. As mineralising fluids propagate in the crust they cause a hydrothermal overprinting of the existing petrofabric. If this overprinting is random, or too weak and thus swamped by the existing signal AMS will not be able to determine any interpretable signal across the vein; however, if this overprinting is a considerable systematic alteration then AMS will identify an imbrication of AMS tensors approaching veins. The South Munster basin of southwest Ireland is a sedimentary deposit of Devonian-Carboniferous age, within which lie the fluvial sediments north of the town of Allihies which are pervaded by copper bearing lodes likely exolved from the underlying marine strata. Analysis of samples from six locations across these veins was used to construct a picture of the AMS as it changes across a mineralised system. Systematic changes across each system are often subtle and interrupted by stronger signals, especially foliation as a result of regional scale low grade compression. However changes in tensor orientation and shape are both observed in instances which could be consistent with a directional overprint caused by the vein.

  5. Vein Controlled Index Mineral Crystal Size Distribution in Barrow's Metamorphic Zones, Glen Esk, Scotland

    NASA Astrophysics Data System (ADS)

    Lewerentz, A.; Skelton, A.; Linde, J. K.; Nilsson, J.; Möller, C.; Crill, P. M.; Spicuzza, M. J.

    2015-12-01

    The concept of index mineral based metamorphic zones was first introduced by George Barrow a little more than 100 years ago, and the Barrovian metamorphic zones are still today used as framework by metamorphic petrologists. Today the importance of metamorphic fluids for driving metamorphic reactions is widely recognised. Even so, a general view is that Barrovian metamorphism is solely controlled by pressure, temperature, and protolith composition. This study aims to establish if and how fluids control index mineral formation and distribution during Barrovian metamorphism. To do so, we use samples from Barrow's own type locality in Glen Esk, Southeast Scottish Highlands, and study possible relationships between veining and index mineral distribution. In addition to petrographic and textural observations and analyses, we also use whole rock chemistry, mineral chemistry, and oxygen isotope analyses. At low grade, in the chlorite zone and most of the biotite zone, no correlation between veining and index mineral distribution is seen. At higher grade, the index mineral abundance is shown to decrease away from veins in the garnet and staurolite zones. Pseudosection analysis show larger garnet stability fields in vein-adjacent rock. In addition, quartz abundance and oxygen isotope ratios of quartz coincidentally decrease, which we interpret as evidence for fluid-rock interaction. The kyanite zone shows a fairly homogenous kyanite distribution, but also indications of extensive fluid-rock interaction, such as high vein density and oxygen isotope ratios in equilibrium with the fluid. Based on our observations and the geochemical datasets, we conclude that fluid played a major role in the stabilisation and distribution of the Barrovian index minerals in Glen Esk, and that the fluid control was larger at higher metamorphic grades.

  6. [Study on Mineralogical Characteristics of Quartz and Calcite from Feieling Skarn-Type Pb-Zn Deposit in Southwest Margin of Yunkai Massif].

    PubMed

    Zeng, Chang-yu; Zhao, Ming-zhen; Li, Hong-zhong; Niu, Jia; Zhang, Jie-tang; He, Jun-guo; Zhou, Yong-zhang; Yang, Zhi-jun

    2015-09-01

    The Feieling Pb-Zn deposit of skarn-type is located the in Southwest margin of Yunkai massif, China. This ore deposit can be divided into wall rock near ore, concealed rock mass, endoskarn, exoskarn and orebody. The Raman and FTIR spectrum are conducted to study the mineralogical characteristics of quartz and calcite from five types of rocks from Feieling skarn-type deposit. The analysis shows that the quartz included in the near ore wall rock, endoskarn and exoskarn, comparing with recrystallized quartz of concealed rock mass, has a tend to change into low symmetry quartz in varying degrees. The crystalinity and order degree of quartz from near ore wall rock to concealed rock mass and to endoskarn are becoming higher, but that of quartz from different exoskarn samples display no regular. The origin or the quartz microstructure changes may be related to the multi-stage evolution of skarn mineralization process. The quartz, included in near ore wall rock, endoskarn and exoskarn, become easier to recrystallize and adjust microstructure under the influence of the multi-stage hydrothermal and temperature effect. In anyone sample, the earlier crystalline calcite, showing subhedral-euhedral crystal, display higher crystalinity and order degree. On the contrary, the later crystalline calcite, showing xenomorphic crystal, display lower crystalinity and order degree. Calcite crystal of exoskarn rock contains some silica impurity, while endoskarn and orebody rock is pure. The purity of calcite crystal may relate to Multi-stage evolution of skarn mineralization process. At the early and late skarn stage, active silica-containing fluid is easier to join into calcite, which is under higher temperature environments. On the contrary, at the late quartz-surfide stage, the later crystalized calcite displays higher purity, which is under lower temperature environments. Therefore, spectral characteristics of quartz and calcite reflect multi-stage evolution of skarn mineralization

  7. Abnormal patterns of the renal veins

    PubMed Central

    Azari, Hassan; Abedinzadeh, Mehdi

    2012-01-01

    Knowledge of the renal vascular anatomy may greatly contribute to the success of surgical, invasive and radiological procedures of the retroperitoneal region. Here, morphometric and histological studies of a human cadaveric specimen presented a complex, anomalous pattern of renal veins. The left renal vein had an oblique retro-aortic course and received two lumbar veins. It bifurcated near its drainage point into the inferior vena cava. The right renal vein received the right testicular vein. In addition, the left kidney was located at a low position. The spleen was enlarged. The present case is unique and provides information that may help surgeons or angiologists to apply safer interventions. PMID:22536553

  8. Adsorption of goethite onto quartz and kaolinite

    USGS Publications Warehouse

    Goldberg, M.C.; Weiner, Eugene R.; Boymel, P.M.

    1984-01-01

    The adsorption of colloidal goethite onto quartz and kaolinite substrates has been studied as a function of pH and NaCl concentration. Goethite adsorption was measured quantitatively by Fourier-transform infrared spectroscopy. The results indicate that adsorption onto both substrates is due primarily to coulombic forces; however, the pH dependence of adsorption is very different for the two substrates. This is explained by the fact that the surface charge on quartz is entirely pH-dependent, while kaolinite has surface faces which carry a permanent negative charge. Adsorption of goethite on to kaolinite increases markedly with increasing NaCl concentration, while adsorption onto quartz is relatively independent of NaCl concentration. This can be explained by the influence of NaCl concentration upon the development of surface charge on the substrates. A method is described for separating surface-bound goethite from free goethite.

  9. Mineralogical, geochemical and isotopic characteristics of hydrothermal alteration processes in the active, submarine, felsic-hosted PACMANUS field, Manus Basin, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Lackschewitz, K. S.; Devey, C. W.; Stoffers, P.; Botz, R.; Eisenhauer, A.; Kummetz, M.; Schmidt, M.; Singer, A.

    2004-11-01

    During ODP Leg 193, 4 sites were drilled in the active PACMANUS hydrothermal field on the crest of the felsic Pual Ridge to examine the vertical and lateral variations in mineralization and alteration patterns. We present new data on clay mineral assemblages, clay and whole rock chemistry and clay mineral strontium and oxygen isotopic compositions of altered rocks from a site of diffuse low-temperature venting (Snowcap, Site 1188) and a site of high-temperature venting (Roman Ruins, Site 1189) in order to investigate the water-rock reactions and associated elemental exchanges. The volcanic succession at Snowcap has been hydrothermally altered, producing five alteration zones: (1) chlorite ± illite-cristobalite-plagioclase alteration apparently overprinted locally by pyrophyllite bleaching at temperatures of 260-310°C; (2) chlorite ± mixed-layer clay alteration at temperatures of 230°C; (3) chlorite and illite alteration; (4) illite and chlorite ± illite mixed-layer alteration at temperatures of 250-260°C; and (5) illite ± chlorite alteration at 290-300°C. Felsic rocks recovered from two holes (1189A and 1189B) at Roman Ruins, although very close together, show differing alteration features. Hole 1189A is characterized by a uniform chlorite-illite alteration formed at ˜250°C, overprinted by quartz veining at 350°C. In contrast, four alteration zones occur in Hole 1189B: (1) illite ± chlorite alteration formed at ˜300°C; (2) chlorite ± illite alteration at 235°C; (3) chlorite ± illite and mixed layer clay alteration; and (4) chlorite ± illite alteration at 220°C. Mass balance calculations indicate that the chloritization, illitization and bleaching (silica-pyrophyllite assemblages) alteration stages are accompanied by different chemical changes relative to a calculated pristine precursor lava. The element Cr appears to have a general enrichment in the altered samples from PACMANUS. The clay concentrate data show that Cr and Cu are predominantly

  10. Mechanical buckling of veins under internal pressure.

    PubMed

    Martinez, Ricky; Fierro, Cesar A; Shireman, Paula K; Han, Hai-Chao

    2010-04-01

    Venous tortuosity is associated with multiple disease states and is often thought to be a consequence of venous hypertension and chronic venous disease. However, the underlying mechanisms of vein tortuosity are unclear. We hypothesized that increased pressure causes vein buckling that leads to a tortuous appearance. The specific aim of this study was to determine the critical buckling pressure of veins. We determined the buckling pressure of porcine jugular veins and measured the mechanical properties of these veins. Our results showed that the veins buckle when the transmural pressure exceeds a critical pressure that is strongly related to the axial stretch ratio in the veins. The critical pressures of the eight veins tested were 14.2 +/- 5.4 and 26.4 +/- 9.0 mmHg at axial stretch ratio 1.5 and 1.7, respectively. In conclusion, veins buckle into a tortuous shape at high lumen pressures or reduced axial stretch ratios. Our results are useful in understanding the development of venous tortuosity associated with varicose veins, venous valvular insufficiency, diabetic retinopathy, and vein grafts. PMID:20094913

  11. Mechanical Buckling of Veins under Internal Pressure

    PubMed Central

    Martinez, Ricky; Fierro, Cesar A.; Shireman, Paula K.; Han, Hai-Chao

    2010-01-01

    Venous tortuosity is associated with multiple disease states and is often thought to be a consequence of venous hypertension and chronic venous disease. However, the underlying mechanisms of vein tortuosity are unclear. We hypothesized that increased pressure causes vein buckling that leads to a tortuous appearance. The specific aim of this study was to determine the critical buckling pressure of veins. We determined the buckling pressure of porcine jugular veins and measured the mechanical properties of these veins. Our results showed that veins buckle when the transmural pressure exceeds a critical pressure that is strongly related to the axial stretch ratio in the veins. The critical pressures of the eight veins tested were 14.2 ± 5.4 mmHg and 26.4 ± 9.0 mmHg at axial stretch ratio 1.5 and 1.7, respectively. In conclusion, veins buckle into a tortuous shape at high lumen pressures or reduced axial stretch ratios. Our results are useful in understanding the development of venous tortuosity associated with varicose veins, venous valvular insufficiency, diabetic retinopathy and vein grafts. PMID:20094913

  12. Leiomyosarcoma of the renal vein.

    PubMed

    Imao, Tetsuya; Amano, Toshiyasu; Takemae, Katsurou

    2011-02-01

    A 43-year-old woman was referred to our clinic for evaluation of a left retroperitoneal mass. She presented to our internal medicine department complaining of back pain. Computed tomography (CT) scan revealed a left retroperitoneal mass 55 mm in size in the hilum of the left kidney. Enhanced CT scan and magnetic resonance imaging (MRI) disclosed a poorly staining mass. Metaiodobenzylguanidine scintigraphy demonstrated no accumulation in the mass; moreover, endocrinologic examination was normal. Laparoscopic resection of the left retroperitoneal tumor was attempted; however, strong adhesion between the tumor and the left renal vein was encountered. Thus, left nephrectomy after open conversion was performed. Histological findings indicated leiomyosarcoma originating from the left renal vein. The postoperative course has been uneventful; neither recurrence nor metastasis is evident 2 years postsurgery. PMID:20694494

  13. [ENDOVENOUS LASER TREATMENT FOR VARICOSE VEINS].

    PubMed

    Tezuka, Masahiro; Kanaoka, Yuji; Ohki, Takao

    2015-05-01

    Varicose veins are a common condition attecting approximately 10 million patients in Japan. The main cause of varicose veins is reflux of the saphenous vein, and conventional treatment for several decades was stripping the affected saphenous vein and phlebectomy. Endovenous laser treatment (EVLT) is a less-invasive treatment method in which the saphenous vein is ablated with a laser under local anesthesia. EVLT has been approved by the Japanese Ministry of Health, Labor and Welfare since 2011, and we have performed EVLT on 5,160 legs with saphenous insufficiency with no severe complications including deep vein thrombosis except for one case of arteriovenous fistula. EVLT appears to be a safe, effective treatment option for varicose veins with saphenous insufficiency. PMID:26281654

  14. Geochemical element mobility during the hydrothermal alteration in the Tepeoba porphyry Cu-Mo-Au deposits at Balikesir, NW Turkey

    NASA Astrophysics Data System (ADS)

    Abdelnasser, Amr; Kiran Yildirim, Demet; Doner, Zeynep; Kumral, Mustafa

    2016-04-01

    The Tepeoba porphyry Cu-Mo-Au deposit represents one of the important copper source and mineral deposits in the Anatolian tectonic belt at Balikesir province, NW Turkey. It considered as a vein-type deposit locally associated with intense hydrothermal alteration within the brecciation, quartz stockwork veining, and brittle fracture zones in the main host rock that represented by hornfels, as well as generally related to the shallow intermediate to silicic intrusive Eybek pluton. Based on the field and geologic relationships and types of ore mineral assemblages and the accompanied alteration types, there are two mineralization zones; hypogene (primary) and oxidation/supergene zones are observed associated with three alteration zones; potassic, phyllic, and propylitic zones related to this porphyry deposit. The phyllic and propylitic alterations locally surrounded the potassic alteration. The ore minerals related to the hypogene zone represented by mostly chalcopyrite, Molybdenite, and pyrite with subordinate amount of marcasite, enargite, and gold. On the other hand they include mainly cuprite with chalcopyrite, pyrite and gold as well as hematite and goethite at the oxidation/supergene zone. This study deals with the quantitative calculations of the mass/volume changes (gains and losses) of the major and trace elements during the different episodes of alteration in this porphyry deposit. These mass balance data reveal that the potassic alteration zone that the main Cu- and Mo-enriched zone, has enrichment of K, Si, Fe, and Mg, and depletion of Na referring to replacement of plagioclase and amphibole by K-feldspar, sericite and biotite. While the propylitic alteration that is the main Mo- and Au-enriched zone is accompanied with K and Na depletion with enrichment of Si, Fe, Mg, and Ca forming chlorite, epidote, carbonate and pyrite. On the other hand the phyllic alteration that occurred in the outer part around the potassic alteration, characterized by less amount

  15. Association of gold with uraninite and pyrobitumen in the metavolcanic rock hosted hydrothermal Au-U mineralisation at Rompas, Peräpohja Schist Belt, northern Finland

    NASA Astrophysics Data System (ADS)

    Molnár, Ferenc; Oduro, Harry; Cook, Nick D. J.; Pohjolainen, Esa; Takács, Ágnes; O'Brien, Hugh; Pakkanen, Lassi; Johanson, Bo; Wirth, Richard

    2016-06-01

    The Peräpohja Schist Belt comprises a supracrustal sequence of quartzites, mafic volcanics and volcaniclastics, carbonate rocks, black shales, mica schists and greywackes which were deposited from ca. 2.44 to ~1.91 Ga, during the rifting of the Archaean basement in the eastern part of the Fennoscandian shield. Metamorphism and multiple folding of the basin fill took place during the Svecofennian orogeny (1.9-1.8 Ga) followed by intrusions of late-orogenic (1.84-1.80 Ga) and post-orogenic granitoids (1.79-1.76 Ga). The Rompas Au-U mineralisation is hosted by deformed calcsilicate veins in mafic volcanic rocks and locally contains very high grade (>10,000 g/t Au) gold pockets with strict spatial association of gold minerals to uraninite and pyrobitumen. Chemical ages from the unaltered domains in the structure of uraninite indicate a 1.95-1.90 Ga age for the deposition of the primary, high temperature (e.g. U/Th < 100 in uraninite) hydrothermal uranium mineralisation. These data are in agreement with the results of previous U-Pb dating of uraninite by SIMS. Textural evidence suggests that metamorphic recrystallisation of the uraninite-bearing quartz-dolomite veins into calcsilicate mineral assemblages during the Svecofennian orogeny (1.9-1.8 Ga) was followed by a hydrocarbon-bearing fluid flow event and radiolytic polymerisation of hydrocarbons around grains of uraninite. Gold precipitated during a subsequent hydrothermal process in the fractures of uraninite, as well as in the cracks and on the botryoidal surfaces of uraninite-pyrobitumen nodules. Remobilisation and redeposition of uranium by these hydrothermal events produced secondary uraninite grains with chemical ages between 1.85 and 1.65 Ga. Native gold is associated with galena, altaite, hunchunite, nickeline and rare cobaltite, Pb-bearing maldonite, pyrite, pyrrhotite, chalcopyrite, molybdenite and titanite. Raman spectra show disordered structure of undeformed pyrobitumen nodules in contrast with the well

  16. Association of gold with uraninite and pyrobitumen in the metavolcanic rock hosted hydrothermal Au-U mineralisation at Rompas, Peräpohja Schist Belt, northern Finland

    NASA Astrophysics Data System (ADS)

    Molnár, Ferenc; Oduro, Harry; Cook, Nick D. J.; Pohjolainen, Esa; Takács, Ágnes; O'Brien, Hugh; Pakkanen, Lassi; Johanson, Bo; Wirth, Richard

    2016-01-01

    The Peräpohja Schist Belt comprises a supracrustal sequence of quartzites, mafic volcanics and volcaniclastics, carbonate rocks, black shales, mica schists and greywackes which were deposited from ca. 2.44 to ~1.91 Ga, during the rifting of the Archaean basement in the eastern part of the Fennoscandian shield. Metamorphism and multiple folding of the basin fill took place during the Svecofennian orogeny (1.9-1.8 Ga) followed by intrusions of late-orogenic (1.84-1.80 Ga) and post-orogenic granitoids (1.79-1.76 Ga). The Rompas Au-U mineralisation is hosted by deformed calcsilicate veins in mafic volcanic rocks and locally contains very high grade (>10,000 g/t Au) gold pockets with strict spatial association of gold minerals to uraninite and pyrobitumen. Chemical ages from the unaltered domains in the structure of uraninite indicate a 1.95-1.90 Ga age for the deposition of the primary, high temperature (e.g. U/Th < 100 in uraninite) hydrothermal uranium mineralisation. These data are in agreement with the results of previous U-Pb dating of uraninite by SIMS. Textural evidence suggests that metamorphic recrystallisation of the uraninite-bearing quartz-dolomite veins into calcsilicate mineral assemblages during the Svecofennian orogeny (1.9-1.8 Ga) was followed by a hydrocarbon-bearing fluid flow event and radiolytic polymerisation of hydrocarbons around grains of uraninite. Gold precipitated during a subsequent hydrothermal process in the fractures of uraninite, as well as in the cracks and on the botryoidal surfaces of uraninite-pyrobitumen nodules. Remobilisation and redeposition of uranium by these hydrothermal events produced secondary uraninite grains with chemical ages between 1.85 and 1.65 Ga. Native gold is associated with galena, altaite, hunchunite, nickeline and rare cobaltite, Pb-bearing maldonite, pyrite, pyrrhotite, chalcopyrite, molybdenite and titanite. Raman spectra show disordered structure of undeformed pyrobitumen nodules in contrast with the well

  17. Petrology and Geochemistry of Hydrothermally Altered Volcanic Rocks in the Iheya North Hydrothermal Field, Middle Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Yamasaki, T.

    2015-12-01

    The Iheya North hydrothermal field is located in the middle Okinawa Trough, a young and actively spreading back-arc basin extending behind the Ryukyu arc-trench system in the southeastern margin of the East China Sea. In this hydrothermal field, two scientific drilling expeditions (IODP Exp 331 and SIP CK14-04) were conducted using a deep-sea drilling vessel "Chikyu," and samples from a total of 27 holes were taken. Through these expeditions, Kuroko-type volcanogenic massive sulfide deposits (VMS), hydrothermally altered volcanic rocks, and pumiceous and pelagic sediments were recovered. The recovered core provided important information about the relationship between hydrothermal activity, alteration, and ore mineralization. Whole-rock major element composition and trace element (TE) patterns of pumices were very similar to those of rhyolites in the middle Okinawa Trough (RMO). However, pumices were relatively enriched in chalcophile elements Sr and Nb, which suggest incipient mineralization. Volcanic rock generally demonstrated strong silicification and was greenish pale gray in color. Regardless of severe alteration, some rock displayed major element composition broadly similar to the RMO. Alteration was evidenced by an increase in the content of SiO2 and MgO, and decrease in Al2O3, Na2O, and K2O content. The most striking geochemical feature of altered volcanic rock was the discordance between texture and the degree of modification of TEs. Some samples showed decussate texture occupied by petal-like quartz with severe silicification, but no prominent disturbance of concentration and patterns of TEs were observed. In contrast, samples with well-preserved igneous porphyritic texture showed very low TE content and modification of TE patterns. These results suggest that the modification of texture and composition of TEs, as well as silicification, do not occur by a uniform process, but several processes. This may reflect the differences in temperature and the

  18. A TEM investigation of shock metamorphism in quartz from the Vredefort dome, South Africa

    NASA Astrophysics Data System (ADS)

    Leroux, Hugues; Reimold, Wolf Uwe; Doukhan, Jean-Claude

    1994-02-01

    The origin of the Vredefort structure in South Africa is still debated. Several causes have been discussed, namely asteroid impact, internal gas explosion or tectonic processes. Evidence of dynamic rock deformation is pervasive in the form of planar features in quartz grains, shatter cones, veins of pseudotachylite and occurrence of coesite and stishovite (high-pressure quartz polymorphs). A number of these characteristics is widely believed to support an impact origin. However, the planar features in quartz, which are generally considered as one of the strongest indicators of impact, are in the Vredefort case considered as anomalous when compared with those from accepted impact structures. We have investigated by optical and transmission electron microscopy (TEM) the defect microstructures in quartz grains from different lithologies sampled at various places at the Vredefort structure. Whatever the locality, only thin mechanical Brazil twin lamellae in the basal plane are observed by TEM. So far, such defects have only been found in quartz from impact sites, but always associated with sets of thin glass lamellae in rhombohedral planes 10-1 n with n = 1, 2, 3, and 4. At the scale of the optical microscope, Brazil twins in (0001) are easily detected in Vredefort quartz grains because of the numerous tiny fluid inclusions which decorate them. Similar alignments of tiny fluid inclusions parallel to other planes are also detected optically, but at the TEM scale no specific shock defects are detected along their traces. If these inclusion alignments initially were shock features, they are now so severely weathered that they can no longer be recognized as unambiguous shock lamellae. Fine-grained coesite was detected in the vicinity of narrow pseudotachylite veinlets in a quartzite specimen, but stishovite was not found, even in areas where its occurrence was previously reported. Finally, definite evidence of high-temperature annealing was observed in all the samples

  19. Hydrothermal Liquefaction of Biomass

    SciTech Connect

    Elliott, Douglas C.

    2010-12-10

    Hydrothermal liquefaction technology is describes in its relationship to fast pyrolysis of biomass. The scope of work at PNNL is discussed and some intial results are presented. HydroThermal Liquefaction (HTL), called high-pressure liquefaction in earlier years, is an alternative process for conversion of biomass into liquid products. Some experts consider it to be pyrolysis in solvent phase. It is typically performed at about 350 C and 200 atm pressure such that the water carrier for biomass slurry is maintained in a liquid phase, i.e. below super-critical conditions. In some applications catalysts and/or reducing gases have been added to the system with the expectation of producing higher yields of higher quality products. Slurry agents ('carriers') evaluated have included water, various hydrocarbon oils and recycled bio-oil. High-pressure pumping of biomass slurry has been a major limitation in the process development. Process research in this field faded away in the 1990s except for the HydroThermal Upgrading (HTU) effort in the Netherlands, but has new resurgence with other renewable fuels in light of the increased oil prices and climate change concerns. Research restarted at Pacific Northwest National Laboratory (PNNL) in 2007 with a project, 'HydroThermal Liquefaction of Agricultural and Biorefinery Residues' with partners Archer-Daniels-Midland Company and ConocoPhillips. Through bench-scale experimentation in a continuous-flow system this project investigated the bio-oil yield and quality that could be achieved from a range of biomass feedstocks and derivatives. The project was completed earlier this year with the issuance of the final report. HydroThermal Liquefaction research continues within the National Advanced Biofuels Consortium with the effort focused at PNNL. The bench-scale reactor is being used for conversion of lignocellulosic biomass including pine forest residue and corn stover. A complementary project is an international collaboration with

  20. Enceladus: Starting Hydrothermal Activity

    NASA Technical Reports Server (NTRS)

    Matson, D. L.; Castillo-Rogez, J. C.; Johnson, T. V.; Lunine, J. I.; Davies, A. G.

    2011-01-01

    We describe a process for starting the hydrothermal activity in Enceladus' South Polar Region. The process takes advantage of fissures that reach the water table, about 1 kilometer below the surface. Filling these fissures with fresh ocean water initiates a flow of water up from an ocean that can be self-sustaining. In this hypothesis the heat to sustain the thermal anomalies and the plumes comes from a slightly warm ocean at depth. The heat is brought to the surface by water that circulates up, through the crust and then returns to the ocean.

  1. Cody hydrothermal system

    SciTech Connect

    Heasler, H.P.

    1982-01-01

    The hot springs of Colter's Hell are the surface manifestations of a much larger hydothermal system. That system has been studied to define its extent, maximum temperature, and mechanism of operation. The study area covers 2700 km/sup 2/ (1040 mi/sup 2/) in northwest Wyoming. Research and field work included locating and sampling the hot springs, geologic mapping, thermal logging of available wells, measuring thermal conductivities, analyzing over 200 oil and gas well bottom-hole temperatures, and compiling and analyzing hydrologic data. These data were used to generate a model for the hydrothermal system.

  2. Hydrothermal REE and Zr mobilization in the Strange Lake peralkaline granitic system: a reaction path model linked to petrological and geochemical observations

    NASA Astrophysics Data System (ADS)

    Gysi, A. P.; Williams-Jones, A. E.

    2013-12-01

    Extreme enrichment and hydrothermal mobilization of rare earth elements (REE) and other high-field strength elements (HFSE; i.e., Zr, Nb, Ta and Ti) is a feature of anorogenic alkaline and peralkaline igneous systems. Strange Lake in Quebec, Canada, is a mid-Proterozoic peralkaline granitic intrusion that is host to a world-class REE and HFSE deposit with >50 Mt of ore (>1.5 wt.% REE and >3 wt.% Zr). We have used Strange Lake as a natural laboratory and linked petrographic observations of the deposit and geochemical data with numerical simulations to constraint physicochemical conditions of hydrothermal REE and Zr mobilization and mineralization. The B-zone, in the NW of Strange Lake, contains a lens-shaped pegmatite-rich zone hosted in subsolvus granite. Three alteration styles were distinguished: i) an acid alteration caused by HCl-HF-bearing fluids from the pegmatites, ii) Na-metasomatism related to aegirinization/hematization of arfvedsonite, and iii) Ca-F-metasomatism involving late interaction of the rocks with a mixture of acidic F-rich and Ca-rich fluids. The acid alteration accounts for most of the hydrothermal mobilization of Zr and REE within and from the pegmatites, whereas the Ca-F-metasomatism is evident as late stage pore space fillings and veins of hydrothermal fluorite and quartz and a fluorite breccia. These different alteration styles are reflected in the bulk rock chemistry by variable mobility of Na, Fe, Al, Ca, F, HFSE and REE distinguishable on isocon diagrams. Elemental X-ray maps of REE- and Zr-minerals show evidence for a decoupled mobilization of LREE, HREE and Zr at different stages of fluid-rock interaction. Numerical simulations of the reaction of pegmatite with saline HF- and HCl-HF-bearing fluids at 400 °C to 250 °C predict the observed trends reasonably well. Fluids with pH <2 led to the formation of quartz and fluorite in the core of the pegmatites, and fluids with pH >4 to the formation of phyllosilicates and continued stability

  3. Cathodoluminescence characterization of quartz grains from the Upper Cretaceous of dinosaur fossil localities in the Gobi desert, Mongolia

    NASA Astrophysics Data System (ADS)

    Saneyoshi, M.; Nishido, H.; Masuda, R.; Tsogtbaatar, K.; Chinzorig, T.

    2013-12-01

    The Upper Cretaceous eolian sediments in Mongolia's Gobi desert are one of the most important occurrences of the dinosaurs in the world. Large numbers of confiscated dinosaur fossils illegally worked out by poachers has been stored in the Mongolian Paleontological Center at Ulaanbaatar. In most cases, their localities are unknown. The purpose of this study is to identify their localities by cathodoluminescence (CL) features of quartz grains attached to the dinosaur specimens by comparing to the quartz samples collected from the sediments of circumjacent resources in this area. This study focuses on the confiscated specimen which makes up the nest with the babies' Protoceratops. Most of all Protoceratops in every growth process, have been discovered from the Djadokhta Formation in the Gobi desert. This formation crops out at Tugrikin Shireh and Bayn Dzak in the central part of the Gobi desert, and is derived from medium- to fine-grained sand mainly composed of quartz grains, of which sedimentary environments should be obvious to be eolian. The formation age of the sand beds at Tugrikin Shireh and Bayn Dzak has been estimated to be Middle Campanian. CL spectra of quartz have been demonstrated to show different features between the quartz from hydrothermal, plutonic, volcanic and metamorphic origins, suggesting the spectra reflect the condition of the quartz formation and the local environment. Therefore, we have applied the CL characterization of quartz grains to the evaluation of the provenance of the desert sediments. The quartz grains after sieving (#60-80 mesh size) were embedded in the brass holders with non-luminescent epoxy resin, and their surfaces were polished with 1 μm diamond abrasive. Color CL images obtained by the Luminoscope exhibit blue, violet and red emissions in the grains, suggesting various types of emission centers in the quartz. SEM-CL analysis was conducted using an SEM (JSM-5410) combined with a grating monochromator (Mono CL2) to measure

  4. Vein harvesting and techniques for infrainguinal bypass.

    PubMed

    Albäck, Anders; Saarinen, Eva; Venermo, Maarit

    2016-04-01

    In order to achieve good long term results after bypass surgery, alongside with good inflow and outflow arteries, the bypass graft material also has an important role. The best patency and limb salvage rates are achieved with autologous vein. If great saphenous vein is not available, acceptable long-term results can be achieved with arm veins and lesser saphenous vein. The quality and size of the vein are important. A small-caliber vein, increased wall thickness, postphlebitic changes and varicosities are associated with a risk of early failure. Preoperative vein mapping with ultrasound reduces readmissions and postoperative surgical site infections. During the mapping, the vein to be used and its main tributaries are marked with a permanent marker pen. To reduce wound complication rates we recommend bridged incisions in vein harvesting. Endoscopic vein harvesting seems to have no benefit compared to open techniques in lower limb bypasses, and has been associated with higher risk of primary patency loss at one year. With deep tunneling of the graft the problems caused by wound infection can be avoided. PMID:26837257

  5. Fluorous-based carbohydrate quartz crystal microbalance.

    PubMed

    Chen, Lei; Sun, Pengfei; Chen, Guosong

    2015-03-20

    Fluorous chemistry has brought many applications from catalysis to separation science, from supramolecular materials to analytical chemistry. However, fluorous-based quartz crystal microbalance (QCM) has not been reported so far. In the current paper, fluorous interaction has been firstly utilized in QCM, and carbohydrate-protein interaction and carbohydrate-carbohydrate interaction have been detected afterward. PMID:25541017

  6. Instantaneous healing of micro-fractures during coseismic slip: Evidence from microstructure and Ti in quartz geochemistry within an exhumed pseudotachylyte-bearing fault in tonalite

    NASA Astrophysics Data System (ADS)

    Bestmann, Michel; Pennacchioni, Giorgio; Mostefaoui, Smail; Göken, Mathias; de Wall, Helga

    2016-06-01

    Exhumed faults within the tonalitic Adamello pluton (Southern Alps) were seismic at depth as indicated by the presence of pseudotachylytes (solidified friction-induced melts). During cooling of tonalite, early-formed joints were first exploited by localized ductile shear zones associated with deposition of quartz veins (at ~ 500 °C), and later by pseudotachylyte-bearing cataclastic faults (at ~ 250-300 °C ambient temperature). Adjacent to pseudotachylytes, quartz of the host tonalite shows pervasive thin (1-10 μm wide) healed micro-fractures and ultra-fine (1-2 μm grain size) recrystallized aggregates along micro-shear zones. Under cathodoluminescence (CL) the healed micro-fractures have a darker gray shade than the host "magmatic" quartz that reflects a change in Ti concentrations ([Ti]) as indicated by NanoSIMS measurements. [Ti] vary from 35-55 ppm in the CL-lighter host quartz to 10-13 ppm along the CL-darker healed micro-fractures. These [Ti] were inherited by the ultra-fine recrystallized aggregates that overprinted both the magmatic quartz and the healed micro-fractures during the high temperature transient related to frictional seismic slip. Based on Ti-in-quartz thermometry, we infer that micro-fracture healing occurred at higher temperatures than the ambient temperatures of faulting (250-300 °C at 0.2 GPa), for which [Ti] < 1 ppm would be expected. Micro-fracture healing can be ascribed to the stage of seismic slip of faults on the basis of the observation that: (i) they are absent in the host rock surrounding high-T quartz veins un-exploited by faults; and (ii) they locally occur at the tip of pseudotachylyte injection veins filling new fractures developed during the propagation of the earthquake rupture. The relatively high [Ti] of micro-fractures are therefore interpreted to reflect quartz healing by a fluid overheated during the initial stages of frictional seismic slip and escaping from fault surface through the damage zone. This suggests that

  7. Fluid circulation and carbonate vein precipitation in the footwall of an oceanic core complex, Ocean Drilling Program Site 175, Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Schroeder, Tim; Bach, Wolfgang; Jöns, Niels; Jöns, Svenja; Monien, Patrick; Klügel, Andreas

    2015-10-01

    Carbonate veins recovered from the mafic/ultramafic footwall of an oceanic detachment fault on the Mid-Atlantic Ridge record multiple episodes of fluid movement through the detachment and secondary faults. High-temperature (˜75-175°C) calcite veins with elevated REE contents and strong positive Eu-anomalies record the mixing of up-welling hydrothermal fluids with infiltrating seawater. Carbonate precipitation is most prominent in olivine-rich troctolite, which also display a much higher degree of greenschist and sub-greenschist alteration relative to gabbro and diabase. Low-temperature calcite and aragonite veins likely precipitated from oxidizing seawater that infiltrated the detachment fault and/or within secondary faults late or post footwall denudation. Oxygen and carbon isotopes lie on a mixing line between seawater and Logatchev-like hydrothermal fluids, but precipitation temperatures are cooler than would be expected for isenthalpic mixing, suggesting conductive cooling during upward flow. There is no depth dependence of vein precipitation temperature, indicating effective cooling of the footwall via seawater infiltration through fault zones. One sample contains textural evidence of low-temperature, seawater-signature veins being cut by high-temperature, hydrothermal-signature veins. This indicates temporal variability in the fluid mixing, possibly caused by deformation-induced porosity changes or dike intrusion. The strong correlation between carbonate precipitation and olivine-rich troctolites suggests that the presence of unaltered olivine is a key requirement for carbonate precipitation from seawater and hydrothermal fluids. Our results also suggest that calcite-talc alteration of troctolites may be a more efficient CO2 trap than serpentinized peridotite.

  8. Older Hydrothermal Activity along the Northern Yellowstone Caldera Margin at Sulphur Creek, Yellowstone Park, Wyoming

    NASA Astrophysics Data System (ADS)

    Manion, J. L.; Larson, P.

    2008-12-01

    The Tuff of Sulphur Creek (480 ka) is well exposed in the Seven Mile Hole area of the Grand Canyon of the Yellowstone River, Yellowstone National Park, Wyoming. The rhyolitic tuff erupted after the collapse of the Yellowstone Caldera (640 ka) and hosts more than 350 vertical meters of hydrothermal alteration. Two epithermal alteration assemblages with different mineral associations have been identified in the area: an illite-silica-pyrite phase and a kaolinite-alunite-silica-pyrite phase. Kaolinite and opal occur along the canyon rim, montmorillonite and other smectites are found at intermediate depths, and illite and sulfides (pyrite) are found deepest in the section. Our work on the north side of the Sevenmile Hole altered area has found a complex system of veining. The veins are concentrated in the eastern portion of the canyon and are less frequent to the west. Brecciated cross-cutting veins ranging from 2 to 30cm wide are found at the base of the canyon. Moving vertically up the canyons walls, the veining style becomes less complex. These veins are about 1 to 1.5cm wide and are not brecciated, occurring less frequently than the brecciated veins. The canyon walls and the canyon rim mainly contain millimeter-scale cross-cutting silica veinlets. These stockwork-like veinlets are the most abundant fracture filling that we find throughout the canyon walls. Veins at the base of the system, found in the stream bed, contain abundant sulfides (mainly pyrite). Sulfides are present in three forms: disseminated in a silica matrix, as massive pyrite in healed fractures, and encrusting clays and silica. The latter is the least common. Disseminated and massive sulfides are typically associated with the matrix in the brecciated veins. Breccias include angular clasts of altered tuff with argillized feldspar phenocrysts and fragments of earlier vein-filling opal. Sulfides are most abundant in the bottom of the canyon and in the western part of the field area. Hydrothermal

  9. Experimental and theoretical investigation of the production of HCl and some metal chlorides in magmatic/hydrothermal systems. Annual report, 1991--1992

    SciTech Connect

    Not Available

    1992-12-31

    In the calculations we have assumed that all apatites are magmatic. The presence of chlorite and altered plagioclase within the granite and quartz-monzodiorite suggests that alteration may play a role in leading to erroneous estimates of initial melt Cl and F for 2 reasons: (1) the apatites may in fact not be magmatic in origin, but are hydrothermal, and (2) the halogen signature of magmatic apatite may be changed due to subsolidus exchange with a hydrothermal fluid. We are currently endeavoring to develop criteria for determining whether apatite composition represents earlier or later stages of magmatic-hydrothermal development.

  10. Hydrothermal alteration of sediments associated with surface emissions from the Cerro Prieto geothermal field

    SciTech Connect

    Valette-Silver, J.N.; Esquer P., I.; Elders, W.A.; Collier, P.C.; Hoagland, J.R.

    1981-01-01

    A study of the mineralogical changes associated with these hydrothermal vents was initiated with the aim of developing possible exploration tools for geothermal resources. The Cerro Prieto reservoir has already been explored by extensive deep drilling so that relationships between surface manifestations and deeper hydrothermal processes could be established directly. Approximately 120 samples of surface sediments were collected both inside and outside of the vents. The mineralogy of the altered sediments studied appears to be controlled by the type of emission. A comparison between the changes in mineralogy due to low temperature hydrothermal activity in the reservoir, seen in samples from boreholes, and mineralogical changes in the surface emission samples shows similar general trends below 180 C: increase of quartz, feldspar and illite, with subsequent disappearance of kaolinite, montmorillonite, calcite and dolomite. These mineral assemblages seem to be characteristic products of the discharge from high intensity geothermal fields.

  11. Assessing the origin of old apparent ages derived by Pb stepwise leaching of vein-hosted epidote from Mount Isa, northwest Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Duncan, Robert J.; Maas, Roland

    2014-12-01

    Epidote metasomatism affected large areas of tholeiitic metabasalts of the ~1,780 Ma Eastern Creek Volcanics in the Western Fold Belt of the Proterozoic Mount Isa inlier. Hydrothermal epidote generally occurs in quartz veins parallel to or boudinaged within the dominant S2 fabrics which formed during the regional metamorphic peak at ~1,570 Ma associated with the Isan orogeny. Previously published stable isotopic and halogen data suggest that the fluids responsible for epidote formation are metamorphic in origin (with an evaporitic component). Application of the Pb stepwise leaching technique to the epidote does not separate radiogenic Pb4+ and common Pb2+, generating little spread in 206Pb/204Pb (between 16.0 and 30.5). The causes for this relatively low range are twofold: There is little radiogenic Pb in the epidotes (the most radiogenic steps account for <1 % of Pb released) and both Pb2+ and uranogenic Pb4+ substitute into the same site in the epidote crystal lattice. Consequently, age regressions using the Pb stepwise leaching data give ages between 150 and 1,500 myrs older than the host rocks and over 450 myrs older than the thermal metamorphic peak. These old ages are attributed to chemical inheritance from the host metabasalts, via radiogenic Pb release by breakdown of phases such as zircon, monazite, titanomagnetite, and ilmenite during metamorphism. This idea is supported by trace element data and chrondrite-normalized rare earth element patterns that are similar to both the metabasalts and epidotes (except for a variable Eu anomaly in the latter). Relatively high fO2 during vein formation (Fe3+ dominates in the epidote crystal lattice) would allow the incorporation of Th4+ and exclusion of U6+ and would explain elevated Th/U ratios (up to 12) in epidote compared with the host metabasalts. Non-incorporation of U would explain the relatively low U/Pb ratios and non-radiogenic character of the epidote. This process may provide a source of metal for the small

  12. Hydrothermal Evolution of the Giant Cenozoic Kadjaran porphyry Cu-Mo deposit, Tethyan metallogenic belt, Armenia, Lesser Caucasus: mineral paragenetic, cathodoluminescence and fluid inclusion constraints

    NASA Astrophysics Data System (ADS)

    Hovakimyan, Samvel; Moritz, Robert; Tayan, Rodrik; Rezeau, Hervé

    2016-04-01

    The Lesser Caucasus belongs to the Central segment of the Tethyan metallogenic belt and it is a key area to understand the metallogenic evolution between the Western & Central parts of the Tethyan belt and its extension into Iran. Zangezur is the most important mineral district in the southernmost Lesser Caucasus. It is a component of the South Armenian block, and it was generated during the convergence and collision of the southern margin of the Eurasian plate and the northern margin of the Arabian plate, and terranes of Gondwana origin (Moritz et al., in press). The Zangezur ore district consists of the Tertiary Meghri-Ordubad composite pluton, which is characterized by a long-lasting Eocene to Pliocene magmatic, tectonic and metallogenic evolution. It hosts major porphyries Cu-Mo and epithermal Au - polymetallic deposits and occurrences, including the giant world class Kadjaran porphyry Cu-Mo deposit (2244 Mt reserves, 0.3% Cu, 0.05% Mo and 0.02 g/t Au). The Kadjaran deposit is hosted by a monzonite intrusion (31.83±0.02Ma; Moritz et al., in press). Detailed field studies of the porphyry stockwork and veins of the different mineralization stages, their crosscutting and displacement relationships and the age relationship between different paragenetic mineral associations were the criteria for distinction of the main stages of porphyry mineralization at the Kadjaran deposit. The economic stages being: quartz- molybdenite, quartz-molybdenite-chalcopyrite, and quartz-chalcopyrite. The main paragenetic association of the Kadjaran porphyry deposit includes pyrite, molybdenite, chalcopyrite, bornite, chalcocite, pyrrhotite, covellite, sphalerite, and galena. Recent field observations in the Kadjaran open pit revealed the presence of epithermal veins with late vuggy silica and advanced argillic alteration in the north-eastern and eastern parts of the deposit. They are distributed as separate veins and have also been recognized in re-opened porphyry veins and in

  13. OH defects in quartz in granitic systems doped with spodumene, tourmaline and/or apatite: experimental investigations at 5-20 kbar

    NASA Astrophysics Data System (ADS)

    Frigo, C.; Stalder, R.; Hauzenberger, C. A.

    2016-07-01

    The incorporation of OH defects in quartz as a function of Li content in the bulk system and pressures was investigated. Quartz crystals were grown in water-saturated granitic systems, containing various amounts Li, B and P, supplied as accessory phases such as spodumene, tourmaline or apatite in the starting mixtures. High pressure experiments were performed at temperatures between 900 and 1100 °C, and pressures between 5 and 20 kbar with a piston cylinder apparatus, and the synthesized quartz crystals were analyzed by IR spectroscopy, electron microprobe and LA-ICP-MS spectroscopy. All IR absorption spectra revealed absorption features that can be assigned to AlOH (3313, 3379 and 3431 cm-1) and (4H)Si defects (3585 cm-1), whereas quartz grown in the Li and B systems exhibited two additional bands related, respectively, to LiOH (3483 cm-1) and BOH defects (3596 cm-1). It was further observed that LiOH incorporation increases with higher spodumene content in the starting material and decreases with pressure, until no LiOH defects are observed at pressure higher than 15 kbar. Specifically, the most pronounced reduction of LiOH defects occurs in a rather narrow pressure interval (10-15 kbar) close to the high-quartz/low-quartz transition. However, the link between the transition and the defect incorporation remains unclear. Li total concentrations always exceed the Li-coupled LiOH defects, suggesting the simultaneous presence of dry AlLi defects. Results of this study suggest that LiOH defects are detectable only in quartz crystals grown from middle and upper crustal sections (such as hydrothermal quartz) and not in quartz from deep roots of orogenic granitoids.

  14. Shifts in leaf vein density through accelerated vein formation in C4 Flaveria (Asteraceae)

    PubMed Central

    McKown, Athena D.; Dengler, Nancy G.

    2009-01-01

    Background and Aims Leaf venation in many C4 species is characterized by high vein density, essential in facilitating rapid intercellular diffusion of C4 photosynthetic metabolites between different tissues (mesophyll, bundle sheath). Greater vein density has been hypothesized to be an early step in C4 photosynthesis evolution. Development of C4 vein patterning is thought to occur from either accelerated or prolonged procambium formation, relative to ground tissue development. Methods Cleared and sectioned tissues of phylogenetically basal C3 Flaveria robusta and more derived C4 Flaveria bidentis were compared for vein pattern in mature leaves and vein pattern formation in developing leaves. Key Results In mature leaves, major vein density did not differ between C3 and C4 Flaveria species, whereas minor veins were denser in C4 species than in C3 species. The developmental study showed that both major and minor vein patterning in leaves of C3 and C4 species were initiated at comparable stages (based on leaf length). An additional vein order in the C4 species was observed during initiation of the higher order minor veins compared with the C3 species. In the two species, expansion of bundle sheath and mesophyll cells occurred after vein pattern was complete and xylem differentiation was continuous in minor veins. In addition, mesophyll cells ceased dividing sooner and enlarged less in C4 species than in C3 species. Conclusions Leaf vein pattern characteristic to C4 Flaveria was achieved primarily through accelerated and earlier offset of higher order vein formation, rather than other modifications in the timing of vein pattern formation, as compared with C3 species. Earlier cessation of mesophyll cell division and reduced expansion also contributed to greater vein density in the C4 species. The relatively late expansion of bundle sheath and mesophyll cells shows that vein patterning precedes ground tissue development in C4 species. PMID:19759038

  15. Pyrite-illite veins in basin-margin facies: evidence for detrital mineral control on pore-fluid evolution

    SciTech Connect

    Bloch, J.D.; Bhattacharyya, D.P.

    1986-05-01

    Diagenesis of the Upper Cambrian Lamotte Sandstone includes the formation of euhedral, predominantly cubic pyrite, and 1M and 2M illite as veins in association with extensive quartz dissolution. The illite in these veins is well crystallized and distinct from pore-filling illite found in the same deposit. The veins occur only in shallow marine-deposited quartzarenites that overlie or are adjacent to basin-margin alluvial fan deposits composed primarily of lithic arenite. Detrital K-feldspar (in volcanic rock fragments) and iron-bearing minerals, particularly biotite, are abundant in the lithic arenites. No apparent source for the sulfur can be identified within the Lamotte Sandstone. Therefore, the authors propose that sulfur-bearing compactional or thermobaric fluids from adjacent basinal facies provided the necessary sulfur for pyrite formation. The migration of these fluids through the lithic arenite, from which iron, potassium, aluminum, and silica were derived, resulted in pyrite and illite deposition in the adjacent quartzarenites. The increased alkalinity and elevated temperature of these fluids resulted in the extensive quartz dissolution. The absence of these pyrite-illite veins in similar quartzarenites basinward of the fan deposits suggests a detrital mineral control on the evolution of these fluids as they migrated through the Lamotte Sandstone. Further, the formation of illite as opposed to kaolinite indicates that these fluids were finally alkaline.

  16. Shear Veins Under High Pore Pressure Condition Along Subduction Interface: Yokonami Mélange, Cretaceous Shimanto Belt, Shikoku, Southwest Japan

    NASA Astrophysics Data System (ADS)

    Hashimoto, Y.; Eida, M.

    2013-12-01

    Fluid pressure along subdcution interface is a key parameter to understand the fault strength, wedge geometry and seismogenic behavior. In this study, we focused on shear veins pervasively observed in exhumed accretionary complex, Yokonami mélange, Cretaceous Shiamanto Belt, Southwest Japan to examine paleo-stress, effective friction coefficient, fluid pressure ratio and fluid pressure along subduction interface. Lithology of the Yokonami mélange is mainly sandstones surrounded by foliated black shales with minor components of basalts, cherts, tuffs, and limestones, representing tectonic mélange textures. Shear veins cutting mélange foliations are pervasively observed. Shear veins are composed of quartz and calcite. Slicken lines and slicken steps are always observed on the surfaces of shear veins. Pressure-temperature conditions for shear veins are about 180MPa and about 200 degree C on the basis of fluid inclusion analysis. Since the distribution of shear veins are related to packages of ocean floor stratigraphy, formation of shear vein can be before underplating and after mélange formation along subduction interface. We conducted multiple inversion method using slip data of shear veins to examine paleo-stress. In the result, we obtained maximum shear stress horizontal to foliations with 0.3 of stress ratio that is defined as (sigma2-sigma3)/(sigma1-sigma3). Effective friction coefficient was estimated as about 0.10-0.22 by the lowest value of ratio of normal and shear stresses in the normalized Mohr's circle on each plane of shear vein. If we put friction coefficient under dry condition as 0.7 because shear veins cut lithified mélange through out, fluid pressure ratio is equivalent to 0.68-0.86. This is very high fluid pressure ratio along subduction plate interface. On the basis of this fluid pressure ratio and P-T conditions of shear veins from fluid inclusion analysis, 7-12km of depth and 20-30 degree C of geothermal gradient were estimated. The age of

  17. Frictional slip of granite at hydrothermal conditions

    USGS Publications Warehouse

    Blanpied, M.L.; Lockner, D.A.; Byerlee, J.D.

    1995-01-01

    To measure the strength, sliding behavior, and friction constitutive properties of faults at hydrothermal conditions, laboratory granite faults containing a layer of granite powder (simulated gouge) were slid. The mechanical results define two regimes. The first regime includes dry granite up to at least 845?? and wet granite below 250??C. In this regime the coefficient of friction is high (?? = 0.7 to 0.8) and depends only modestly on temperature, slip rate, and PH2O. The second regime includes wet granite above ~350??C. In this regime friction decreases considerably with increasing temperature (temperature weakening) and with decreasing slip rate (velocity strengthening). These regimes correspond well to those identified in sliding tests on ultrafine quartz. The results highlight the importance of fluid-assisted deformation processes active in faults at depth and the need for laboratory studies on the roles of additional factors such as fluid chemistry, large displacements, higher concentrations of phyllosilicates, and time-dependent fault healing. -from Authors

  18. Preduodenal portal vein: its surgical significance.

    PubMed

    Makey, D A; Bowen, J C

    1978-11-01

    Preduodenal portal vein is a rare anatomical variant which may be one of many anomalies in the neonate with duodenal "atresia." Preduodenal portal vein also may be an occasional finding in an adult undergoing biliary, gastric, or pancreatic surgery. Awareness and recognition of the anomaly are essential for the avoidance of injury during such operations. We report here a symptomless patient whose preduodenal portal vein was discovered at cholecystectomy. PMID:715684

  19. Laser leg vein treatment: a brief overview.

    PubMed

    Ross, Victor; Domankevitz, Yacov

    2003-12-01

    Laser treatment of leg veins has been associated with a number of disadvantages, but the introduction of new devices has increased the role of lasers in the treatment of leg veins. This paper reviews the role of laser devices applied from the surface in the treatment of reticular and spider veins. Success is determined by the proper selection of wavelength, fluence, pulse duration, spot size, and number and frequency of treatments. PMID:14741827

  20. The adrenal and renal veins of man and their connections with azygos and lumbar veins.

    PubMed

    Monkhouse, W S; Khalique, A

    1986-06-01

    There exist many variations in the manner of formation, dimensions and place of termination of the central adrenal veins. In addition, some superficial adrenal veins may be substantial in size and may themselves drain directly into the renal veins and/or into other vessels which communicate with azygos and lumbar veins. This provides a route for venous adrenal blood to the heart via the azygos system and the superior vena cava rather than via the inferior vena cava. Variations in the formation and disposition of the renal veins are also described and the patterns of communication between somatic veins (including veins of the azygos and lumbar systems) and the left renal vein are illustrated and discussed in relation to the findings of others. PMID:3693053

  1. Complex fragmentation and silicification structures in fault zones: quartz crystallization and repeated fragmentation in the Rusey fault zone (Cornwall/UK)

    NASA Astrophysics Data System (ADS)

    Yilmaz, Tim I.; Blenkinsop, Tom; Duschl, Florian; Kruhl, Jörn H.

    2015-04-01

    Silicified fault rocks typically show structures resulting from various stages of fragmentation and quartz crystallization. Both processes interact episodically and result in complex structures on various scales, which require a wide spectrum of analysis tools. Based on field and microstructural data, the spatial-temporal connection between deformation, quartz crystallization and fluid and material flow along the Rusey fault zone was investigated. The fault can be examined in detail in three dimensions on the north Cornwall coast, UK. It occurs within Carboniferous sandstones, siltstones, mudstones and slates of the Culm basin, and is likely to have had a long history. The fault rocks described here formed during the younger events, possibly due to Tertiary strike-slip reactivation. Frequent fragmentation, flow and crystallization events and their interaction led to various generations of complex-structured quartz units, among them quartz-mantled and partly silicified wall-rock fragments, microcrystalline quartz masses of different compositions and structures, and quartz vein patterns of various ages. Lobate boundaries of quartz masses indicate viscous flow. Fragments are separated by quartz infill, which contains cm-sized open pores, in which quartz crystals have pyramidal terminations. Based on frequent occurrence of feathery textures and the infill geometry, quartz crystallization from chalcedony appears likely, and an origin from silica gel is discussed. Fragmentation structures are generally fractal. This allows differentiation between various processes, such as corrosive wear, wear abrasion and hydraulic brecciation. Material transport along the brittle shear zone, and displacement of the wall-rocks, were at least partly governed by flow of mobile fluid-quartz-particle suspensions. The complex meso- to microstructures were generated by repeated processes of fragmentation, quartz precipitation and grain growth. In general, the brittle Rusey fault zone

  2. The mangazeya Ag-Pb-Zn vein deposit hosted in sedimentary rocks, Sakha-Yakutia, Russia: Mineral assemblages, fluid inclusions, stable isotopes (C, O, S), and origin

    NASA Astrophysics Data System (ADS)

    Anikina, E. Yu.; Bortnikov, N. S.; Klubnikin, G. K.; Gamyanin, G. N.; Prokof'ev, V. Yu.

    2016-05-01

    The succession of mineral assemblages, chemistry of gangue and ore minerals, fluid inclusions, and stable isotopes (C, O, S) in minerals have been studied in the Mangazeya silver-base-metal deposit hosted in terrigenous rocks of the Verkhoyansk Fold-Thrust Belt. The deposit is localized in the junction zone of the Kuranakh Anticlinorium and the Sartanga Synclinorium at the steep eastern limb of the Endybal Anticline. The deposit is situated at the intersection of the regional Nyuektame and North Tirekhtyakh faults. Igneous rocks are represented by the Endybal massif of granodiorite porphyry 97.8 ± 0.9 Ma in age and dikes varying in composition. One preore and three types of ore mineralization separated in space are distinguished: quartz-pyrite-arsenopyrite (I), quartz-carbonate-sulfide (II), and silver-base-metal (III). Quartz and carbonate (siderite) are predominant in ore veins. Ore minerals are represented by arsenopyrite, pyrite, sphalerite, galena, fahlore, and less frequent sulfosalts. Three types of fluid inclusions in quartz differ in phase compositions: two- or three-phase aqueous-carbon dioxide (FI I), carbon dioxide gas (FI II), and two-phase (FI III) containing liquid and a gas bubble. The homogenization temperature and salinity fall within the ranges of 367-217°C and 13.8-2.6 wt % NaCl equiv in FI I; 336-126°C and 15.4-0.8 wt % NaCl equiv in FI III. Carbon dioxide in FI II was homogenized in gas at +30.2 to +15.3°C and at +27.2 to 29.0°C in liquid. The δ34S values for minerals of type I range from-1.8 to +4.7‰ (V-CDT); of type II, from-7.4 to +6.6‰; and of type III, from-5.6 to +7.1‰. δ13C and δ18O vary from-7.0 to-6.7‰ (V-PDB) and from +16.6 to +17.1 (V-SMOW) in siderite-I; from-9.1 to-6.9‰ (V-PDB) and from +14.6 to +18.9 (V-SMOW) in siderite-II; from-5.4 to-3.1‰ (V-PDB) and from +14.6 to +19.5 (V-SMOW) in ankerite; and from-4.2 to-2.9‰ (V-PDB) and from +13.5 to +16.8 (V-SMOW) in calcite. The data on mineral assemblages, fluid

  3. Millimeter And Submillimeter-Wave Integrated Circuits On Quartz

    NASA Technical Reports Server (NTRS)

    Mehdi, Imran; Mazed, Mohammad; Siegel, Peter; Smith, R. Peter

    1995-01-01

    Proposed Quartz substrate Upside-down Integrated Device (QUID) relies on UV-curable adhesive to bond semiconductor with quartz. Integrated circuits including planar GaAs Schottky diodes and passive circuit elements (such as bandpass filters) fabricated on quartz substrates. Circuits designed to operate as mixers in waveguide circuit at millimeter and submillimeter wavelengths. Integrated circuits mechanically more robust, larger, and easier to handle than planar Schottky diode chips. Quartz substrate more suitable for waveguide circuits than GaAs substrate.

  4. The Black Pearl mine, Arizona - Wolframite veins and stockscheider pegmatite related to an albitic stock

    NASA Technical Reports Server (NTRS)

    Schmitz, Christopher; Burt, Donald M.

    1990-01-01

    Wolframite-bearing quartz veins flanked by greisen alteration occur at and near the Black Pearl mine, Yavapai County, Arizona. The veins are genetically related to a small albitite stock, and cut a series of Proterozoic metasedimentary and intrusive rocks. The largest vein, the only one mined, is located at the apex of the stock. Field relations imply that this stock is a late-stage differentiate of time 1.4-Ga anorogenic Lawler Peak batholith, which crops out about 3 km to the south. The albitites are of igneous origin and have suffered only minor deuteric alteration. A thin (1 to 2 m) pegmatite unit ('stockscheider') occurs at the contact of the Black Pearl Albitite stock with the country rocks. Directional indicators and other evidence suggest that the pegmatite was formed in the presence of a volatile-rich fluid phase close to the time of magma emplacement. The sudden change from coarse-grained microcline-rich pegmatite to fine-grained, albite-rich albitite suggests pressure quenching, possibly due to escape of fluids up the Black Pearl vein. Stockscheider-like textures typically occur near the apical contacts of productive plutons. The presence or absence of this texture is a useful guide in prospecting for lithophile metal deposits.

  5. Remodelling of the Superior Caval Vein After Angioplasty in an Infant with Superior Caval Vein Syndrome

    SciTech Connect

    Mert, Murat Saltik, Levent; Gunay, Ilhan

    2004-08-15

    An 8-month old girl was presented with superior caval vein syndrome early after cardiac surgery. Angiography showed severe stenosis of the superior caval vein with 50 mmHg pressure gradient. Following balloon angioplasty, the pressure gradient was reduced to 7 mmHg with some residual stenosis of the superior caval vein. When the patient was reevaluated 5 months after the procedure, angiography revealed a normal diameter of the superior caval vein without a pressure gradient.

  6. Model of the porphyry copper and polymetallic vein family of deposits - Applications in Slovakia, Hungary, and Romania

    USGS Publications Warehouse

    Drew, L.J.

    2003-01-01

    A tectonic model useful in estimating the occurrence of undiscovered porphyry copper and polymetallic vein systems has been developed. This model is based on the manner in which magmatic and hydrothermal fluids flow and are trapped in fault systems as far-field stress is released in tectonic strain features above subducting plates (e.g. strike-slip fault systems). The structural traps include preferred locations for stock emplacement and tensional-shear fault meshes within the step-overs that localize porphyry- and vein-style deposits. The application of the model is illustrated for the porphyry copper and polymetallic vein deposits in the Central Slovakian Volcanic Field, Slovakia; the Ma??tra Mountains, Hungary; and the Apuseni Mountains, Romania.

  7. Characterization of Quartz and Feldspar Deformation in the Mid-crust: Insights from the Cordillera Blanca Shear Zone, Peru

    NASA Astrophysics Data System (ADS)

    Hughes, C. A.; Jessup, M. J.; Shaw, C. A.

    2014-12-01

    Deformation mechanisms within shear zones from various crustal levels must be characterized to develop accurate models of lithospheric rheology. The Cordillera Blanca Shear Zone (CBSZ) in the central Peruvian Andes records changes in temperature, microstructures, and deformation mechanisms that occurred during exhumation through the brittle-ductile-transition during normal-sense slip over the last ~5 m.y. The 100-500-m-thick mylonitic shear zone occupies the footwall of a 200-km-long normal detachment fault, marking the western boundary of the 8 Ma, leucogranodiorite Cordillera Blanca Batholith. Though local variations do occur, including recrystallized quartz veins and local, decimeter- to meter- scale shear zones, the CBSZ follows a general trend of increasing strain towards the detachment. Structurally lowest positions are weakly deformed and transition to protomylonite, mylonite, and ultramylonite at higher positions, truncating at a cataclasite nearest the detachment. We characterize strain using EBSD analyses of quartz lattice preferred orientations and deformation temperatures using quartz and feldspar textures and two-feldspar thermometry of asymmetric strain-induced myrmekite. At the deepest structural positions, feldspar grains record a complex history characterized by bulging recrystallization, myrmekite formation, and brittle fracture, while quartz exhibits dominant grain-boundary migration recrystallization (T> 500 °C) and prism slip. Intermediate samples exhibit more prevalent strain-induced myrmekite, brittle fracture in feldspar, and reaction-associated recrystallization of K-feldspar to mica; quartz records mainly subgrain-rotation recrystallization (400-500 °C) and dominant prism slip with a rhomb component. Shallower positions preserve fewer, smaller, and more rounded feldspar porphyroclasts with no myrmekite, and dominant bulging recrystallization (280-400 °C) in quartz that records prism , rhomb , and some basal slip.

  8. Late Paleozoic strike-slip faults and related vein arrays of Cape Elizabeth, Maine

    NASA Astrophysics Data System (ADS)

    Swanson, Mark T.

    2006-03-01

    Strike-slip faults and related quartz vein arrays of Late Paleozoic-age cut gently-dipping metasedimentary rocks at Cape Elizabeth in southern coastal Maine and formed in response to regional dextral shearing along the Norumbega fault system. Vertical quartz veins up to 20 m wide and 10s of meters long were emplaced orthogonal to the local shear zone-parallel elongation fabric, reflecting strain partitioning during transpression. Earlier veins were reoriented by clockwise rotation toward this NE-trending regional shear direction. The later brittle strike-slip faults are oblique to the regional shear direction and interpreted as a 10-km-scale R-shear array on the southeast flank of the Norumbega fault system. These left-stepping en échelon fault zones consist of the three Two Lights fault zones (˜200 m lengths and up to ˜5 m displacements) and the Richmond Island fault zone (˜1.6 km length and ˜40 m displacement). Displacements on these fault zones have developed fine-grained silicified, obliquely-foliated and laminated cataclasites and locally, millimeter-thin pseudotachylyte fault and injection veins. Individual fault core zones are up to 10s of centimeters thick as part of several complex anastamosing zones of faulting 10s of meters wide. Initial segments within each fault zone are typically terminated with oblique extension fractures in horsetail configurations. The left-stepping en échelon relationships between these segments led to dominantly contractional step-over zones where P-shear linkages created a through-going fault that truncated the ends of the earlier-formed terminated segments. This linkage-growth model for fault zone evolution works toward larger scales and longer fault lengths as displacement accumulates, within a limiting maximum displacement/length ratio characteristic of the host lithologies. Length-frequency data for fault segments within these zones suggest a transition to linkage-dominated growth once fault segments were longer than

  9. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, Bhushan L.

    1996-01-01

    An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the wall of the muffle is also provided for controlling the source of optical energy.

  10. Crack Healing in Quartz: Influence of Crack Morphology and pOH-

    NASA Astrophysics Data System (ADS)

    Fallon, J. A.; Kronenberg, A. K.; Popp, R. K.; Lamb, W. M.

    2004-12-01

    Crack healing in quartz has been investigated by optical microscopy and interferometry of rhombohedral r-cleavage cracks in polished Brazilian quartz prisms that were hydrothermally annealed. Quartz prisms were pre-cracked at room temperature and then annealed at temperatures T of 250° and 400° C for 2.4 to 240 hours, fluid pressure Pf = 41 MPa (equal to confining pressure Pc), and varying pOH- (from 5.4 to 1.2 at 250° C for fluids consisting of distilled water and NaOH solutions). Crack morphologies before and after annealing were recorded for each sample in plane light digital images and apertures were determined from interference fringes recorded using transmitted monochromatic light (λ = 598 nm). As documented in previous studies (Smith and Evans, 1984; Brantley et al., 1990; Beeler and Hickman, 1996), crack healing of quartz is driven by reductions in surface energy and healing rates appear to be limited by diffusional solute transport; sharply defined crack tips become blunted and break up into fluid-filled tubes and inclusions. However, fluid inclusion geometries are also observed with nonequilibrium shapes that depend on initial surface roughness. Crack healing is significant at 400° C after short run durations (24 hr) with healing rates reaching 10-5 mm/s. Crack healing is also observed at T=250° C, but only for smooth cracks with apertures < 0.6 μ m or for cracks subject to low pOH-. The extent of crack healing is sensitive to crack aperture and to hackles formed by fine-scale crack branching during crack growth. Initial crack apertures appear to be governed by the presence of fine particles, often found in the vicinity of hackles, which maintain the separation of crack surfaces. Where rough cracks exhibit healing, hackles are sites of either enhanced or reduced loss of fluid-solid interface depending on slight mismatches and sense of twist of opposing crack surfaces. Hackles of open r-cleavage cracks are replaced either by (1) healed curvilinear

  11. Hydrothermal processes at seafloor spreading centers,

    SciTech Connect

    Sleep, N.H.

    1983-01-01

    This chapter discusses the initial entry of hydrothermal seawater into deep levels of the oceanic crust, the effectiveness of hydrothermal circulation in cooling the crust, the geometry of hydrothermal circulation, the relationship between the hydrothermal circulation and the magma chamber, the reaction of the oceanic crust with the seawater, and the identification of the hydrothermal fluid which alters a rock sample. Topics considered include the crack front, observation relevant to the crack front, the limitations of the crack front hypothesis, the observed pattern of hydrothermal alteration, the nature of the hydrothermal fluid, the physics of large scale convection, and convection through crack zones. Knowledge of hydrothermal circulation at the ridge axis is based on sampling of the hydrothermal fluid, indirect geophysical measurements of the oceanic crust, and studies of rocks which are believed to have undergone hydrothermal alteration at the ridge axis. Includes 2 drawings.

  12. What Are the Signs and Symptoms of Varicose Veins?

    MedlinePlus

    ... from the NHLBI on Twitter. What Are the Signs and Symptoms of Varicose Veins? The signs and symptoms of varicose veins include: Large veins ... skin in the area around the varicose vein. Signs of telangiectasias are clusters of red veins that ...

  13. Hysteresis in quartz resonators-a review.

    PubMed

    Kusters, J A; Vig, J R

    1991-01-01

    The literature on the frequency versus temperature characteristics of quartz crystal resonators is reviewed. Three papers that deal with frequency versus pressure hysteresis are included, as these may possibly have relevance to frequency versus temperature hysteresis. It is seen that the causes of hysteresis are not well understood. The evidence to date is inconclusive. The mechanisms that can cause hysteresis include: strain changes changes in the quartz, contamination redistribution, oscillator circuitry hysteresis, and apparent hysteresis due to thermal gradients. The results to date seem to indicate that lattice defects are somehow related to thermal hysteresis. Stress relief in the mounting structure can also produce significant hysteresis. As crystal processing techniques have improved. contamination has become less of a problem. PMID:18267585

  14. Multi-quartz-enhanced photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Ma, Yufei; Yu, Xin; Yu, Guang; Li, Xudong; Zhang, Jingbo; Chen, Deying; Sun, Rui; Tittel, Frank K.

    2015-07-01

    A multi-quartz-enhanced photoacoustic spectroscopy (M-QEPAS) sensor system for trace gas detection is reported. Instead of a single quartz tuning fork (QTF) as used in QEPAS technique, a dual QTF sensor platform was adopted in M-QEPAS to increase the signal strength by the addition of the detected QEPAS signals. Water vapor was selected as the target analyte. M-QEPAS realized a 1.7 times signal enhancement as compared to the QEPAS method for the same operating conditions. A minimum detection limit of 23.9 ppmv was achieved for the M-QEPAS sensor, with a calculated normalized noise equivalent absorption coefficient of 5.95 × 10-8 cm-1W/√Hz. The M-QEPAS sensor performance can be further improved when more QTFs are employed or an acoustic micro-resonator architecture is used.

  15. Quartz-superconductor quantum electromechanical system

    NASA Astrophysics Data System (ADS)

    Woolley, M. J.; Emzir, M. F.; Milburn, G. J.; Jerger, M.; Goryachev, M.; Tobar, M. E.; Fedorov, A.

    2016-06-01

    We propose and analyze a quantum electromechanical system composed of a monolithic quartz bulk acoustic wave oscillator coupled to a superconducting transmon qubit via an intermediate L C electrical circuit. Monolithic quartz oscillators offer unprecedentedly high effective masses and quality factors for the investigation of mechanical oscillators in the quantum regime. Ground-state cooling of such mechanical modes via resonant piezoelectric coupling to an L C circuit, which is itself sideband cooled via coupling to a transmon qubit, is shown to be feasible. The fluorescence spectrum of the qubit, containing motional sideband contributions due to the couplings to the oscillator modes, is obtained and the imprint of the electromechanical steady state on the spectrum is determined. This allows the qubit to function both as a cooling resource for, and transducer of, the mechanical oscillator. The results described are relevant to any hybrid quantum system composed of a qubit coupled to two (coupled or uncoupled) thermal oscillator modes.

  16. Shear veins observed within anisotropic fabric at high angles to the maximum compressive stress

    NASA Astrophysics Data System (ADS)

    Fagereng, Åke; Remitti, Francesca; Sibson, Richard H.

    2010-07-01

    Some faults seem to slip at unusually high angles (>45°) relative to the orientation of the greatest principal compressive stress. This implies that these faults are extremely weak compared with the surrounding rock. Laboratory friction experiments and theoretical models suggest that the weakness may result from slip on a pre-existing frictionally weak surface, weakening from chemical reactions, elevated fluid pressure or dissolution-precipitation creep. Here we describe shear veins within the Chrystalls Beach accretionary mélange, New Zealand. The mélange is a highly sheared assemblage of relatively competent rock within a cleaved, anisotropic mudstone matrix. The orientation of the shear veins-compared with the direction of hydrothermal extension veins that formed contemporaneously-indicates that they were active at an angle of 80°+/-5° to the greatest principal compressive stress. We show that the shear veins developed incrementally along the cleavage planes of the matrix. Thus, we suggest that episodic slip was facilitated by the anisotropic internal fabric, in a fluid-overpressured, heterogeneous shear zone. A similar mechanism may accommodate shear at high angles to the greatest principal compressive stress in a range of tectonic settings. We therefore conclude that incremental slip along a pre-existing planar fabric, coupled to high fluid pressure and dissolution-precipitation creep, may explain active slip on severely misoriented faults.

  17. Tin-tungsten mineralizing processes in tungsten vein deposits: Panasqueira, Portugal

    NASA Astrophysics Data System (ADS)

    Lecumberri-Sanchez, P.; Pinto, F.; Vieira, R.; Wälle, M.; Heinrich, C. A.

    2015-12-01

    Tungsten has a high heat resistance, density and hardness, which makes it widely applied in industry (e.g. steel, tungsten carbides). Tungsten deposits are typically magmatic-hydrothermal systems. Despite the economic significance of tungsten, there are no modern quantitative analytical studies of the fluids responsible for the formation of its highest-grade deposit type (tungsten vein deposits). Panasqueira (Portugal) is a tungsten vein deposit, one of the leading tungsten producers in Europe and one of the best geologically characterized tungsten vein deposits. In this study, compositions of the mineralizing fluids at Panasqueira have been determined through combination of detailed petrography, microthermometric measurements and LA-ICPMS analyses, and geochemical modeling has been used to determine the processes that lead to tungsten mineralization. We characterized the fluids related to the various mineralizing stages in the system: the oxide stage (tin and tungsten mineralization), the sulfide stage (chalcopyrite and sphalerite mineralization) and the carbonate stage. Thus, our results provide information on the properties of fluids related with specific paragenetic stages. Furthermore we used those fluid compositions in combination with host rock mineralogy and chemistry to evaluate which are the controlling factors in the mineralizing process. This study provides the first quantitative analytical data on fluid composition for tungsten vein deposits and evaluates the controlling mineralization processes helping to determine the mechanisms of formation of the Panasqueira tin-tungsten deposit and providing additional geochemical constraints on the local distribution of mineralization.

  18. Error analysis of quartz crystal resonator applications

    SciTech Connect

    Lucklum, R.; Behling, C.; Hauptmann, P.; Cernosek, R.W.; Martin, S.J.

    1996-12-31

    Quartz crystal resonators in chemical sensing applications are usually configured as the frequency determining element of an electrical oscillator. By contrast, the shear modulus determination of a polymer coating needs a complete impedance analysis. The first part of this contribution reports the error made if common approximations are used to relate the frequency shift to the sorbed mass. In the second part the authors discuss different error sources in the procedure to determine shear parameters.

  19. Idiopathic Bilateral External Jugular Vein Thrombosis

    PubMed Central

    Hindi, Zakaria; Fadel, Ehab

    2015-01-01

    Patient: Male, 21 Final Diagnosis: Idiopathic bilateral external jugular vein thrombosis Symptoms: Face engorgement • neck swelling Medication: — Clinical Procedure: None Specialty: Hematology Objective: Unknown ethiology Background: 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. Case Report: 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. Conclusions: 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

  20. U-Pb and Ar-Ar geochronology of the Fujiawu porphyry Cu-Mo deposit, Dexing district, Southeast China: Implications for magmatism, hydrothermal alteration, and mineralization

    NASA Astrophysics Data System (ADS)

    Li, Xiaofeng; Hu, Ruizhong; Rusk, Brian; Xiao, Rong; Wang, Cuiyun; Yang, Feng

    2013-09-01

    The Fujiawu porphyry Cu-Mo deposit is one of several porphyry Cu-Mo deposits in the Dexing district, Jiangxi Province, Southeast China. New zircon SHRIMP U-Pb data yield a weighted mean 206Pb/238U age of 172.0 ± 2.1 and 168.5 ± 1.4 Ma from weakly altered granodiorite porphyry and quartz diorite porphyry, respectively. Two hydrothermal biotites from granodiorite porphyry give an Ar-Ar step-heating plateau age of 169.9 ± 1.8 and 168.7 ± 1.8 Ma. Hydrothermal apatite exsolved from altered biotite yields an isotope dilution thermal ionization mass spectrometry isochron age of 164.4 ± 0.9 Ma. The apatite age is similar to the ages obtained from hydrothermal rutile (165.0 ± 1.1 and 164.8 ± 1.6 Ma) and indicates that the magmatism and hydrothermal activity in the Fujiawu deposit occurred in the Middle Jurassic. Hydrothermal fluid circulation related to multiple stages of magma emplacement resulted in Cu-Mo mineralization in the Fujiawu porphyry deposit. The zircon SHRIMP U-Pb ages and the published molybdenite Re-Os age (170.9 ± 1.5 Ma) represent the timing of magma crystallization and Mo mineralization, whereas the rutile and apatite U-Pb ages reflect the timing of Cu mineralization following quartz diorite emplacement. The data suggest slow cooling after emplacement of the quartz diorite porphyry.

  1. Instantaneous healing of micro-fractures during coseismic slip: evidence from microstructure and Ti in quartz geochemistry within an exhumed pseudotachylyte-bearing fault in tonalite

    NASA Astrophysics Data System (ADS)

    Bestmann, Michel; Pennacchioni, Giorgio; Moustefaoui, Smail; Göken, Mathias; de Wall, Helga

    2016-04-01

    This study presents detailed microstructural and trace element (Ti) analysis of quartz deformation microstructures associated with seismic slip in order to constrain the complex deformation history during an earthquake event. Exhumed faults within the tonalitic Adamello pluton (Southern Alps) were seismic at depth as indicated by the presence of pseudotachylytes (solidified friction-induced melts). During cooling of tonalite, early-formed joints were first exploited by localized ductile shear zones associated with deposition of quartz veins (at ~500 °C), and later by pseudotachylyte-bearing cataclastic faults (at ~250-300 °C ambient temperature). Adjacent to pseudotachylytes, quartz of the host tonalite shows pervasive thin (1-10 μm wide) healed micro-fractures and ultra-fine (1-2 μm grain size) recrystallized aggregates along micro-shear zones. Under cathodoluminescence (CL) the healed micro-fractures have darker gray shade than the host "magmatic" quartz that reflects a change in Ti concentrations [Ti] as indicated by NanoSIMS measurements. [Ti] vary from 35-55 ppm of the CL-lighter host quartz to 11-15 ppm along the CL-darker healed micro-fractures. These [Ti] were inherited by overprinting recrystallization aggregates developed during the high temperature transient related to frictional seismic slip. Based on Ti-in-quartz thermometry, micro-fracture healing occurred at higher temperatures than the ambient temperatures of faulting (250-300 °C at 0.2 GPa). Micro-fracture healing can be ascribed to the stage of seismic slip of faulting on the basis of the observation that: (i) they are absent in the host rock surrounding earlier high-T quartz veins un-exploited by faults; (ii) they locally occur at the tip of pseudotachylyte injection veins filling new fractures developed during the propagation of the earthquake rupture tip. The relatively high [Ti] of micro-fractures are interpreted to reflect quartz healing by a fluid overheated during the initial stages of

  2. Rate equations for sodium catalyzed quartz dissolution

    NASA Astrophysics Data System (ADS)

    Rimstidt, J. Donald

    2015-10-01

    Quartz dissolution rate data were fit to an equation that predicts the dissolution flux (J, mol/m2 sec) as a function of temperature (T, K), sodium concentration (mNa+, molal), and hydrogen ion activity (aH+). The same data fit equally well to an equation that expresses the rate as a function of temperature, sodium concentration, and hydroxide ion activity (aOH-) . These equations are more convenient to use than those given by Bickmore et al. (2008) because rates can be predicted without the implementation of a surface speciation model. They predict that at 25 °C quartz dissolves more than 200 times faster in seawater than in pure water. These two equations fit the data just as well as five other equations from Bickmore et al. (2008) that are based on surface species concentrations. All of these rate equations contain information about the reaction mechanism(s) for quartz dissolution but that information is ambiguous because the independent variables used to develop the equations are correlated. This means that rate equations alone cannot be used to infer the dissolution mechanism. Existing surface complexation, surface charge, terrace-ledge-kink, and Lewis acid-base models must be modified and amalgamated in order to develop a reliable model of the reaction mechanism(s).

  3. Quartz-superconductor quantum electromechanical system

    NASA Astrophysics Data System (ADS)

    Woolley, Matt; Emzir, Muhammad; Milburn, Gerard; Jerger, Markus; Goryachev, Maxim; Tobar, Mike; Fedorov, Arkady

    Quartz bulk acoustic wave oscillators support mechanical modes with very high resonance frequencies and extremely high quality factors. As such, they provide an appealing platform for quantum optics experiments with phonons, gravitational wave detection, and tests of quantum mechanics. We propose to cool and measure the motion of a quartz oscillator using a transmon, with the coupling mediated by a tuneable superconducting LC circuit. The mechanical motion (~250MHz) is resonantly coupled to the LC circuit (~250MHz) by a piezoelectric interaction, the LC circuit is coupled to the transmon (~8GHz) via sideband transitions, and there is a smaller direct coupling between the quartz oscillator and the transmon. By driving the transmon on its red sideband, the mechanical and electrical oscillators may be cooled close to their quantum ground state. By observing the fluorescence of the qubit, the occupations of the oscillators may be determined via the motional sidebands they induce. A minimal model of this system consists of a qubit coupled to two oscillators, which are themselves mutually coupled. The steady-state of the system and the qubit fluorescence spectrum are evaluated analytically using a perturbative projection operator technique, and verified numerically.

  4. Granite-hosted molybdenite mineralization from Archean Bundelkhand craton-molybdenite characterization, host rock mineralogy, petrology, and fluid inclusion characteristics of Mo-bearing quartz

    NASA Astrophysics Data System (ADS)

    Pati, J. K.; Panigrahi, M. K.; Chakarborty, M.

    2014-06-01

    The dominantly high-K, moderate to high SiO2 containing, variably fractionated, volcanic-arc granitoids (± sheared) from parts of Bundelkhand craton, northcentral India are observed to contain molybdenite (Mo) in widely separated 23 locations in the form of specks, pockets, clots and stringers along with quartz ± pyrite ± arsenopyrite ± chalcopyrite ± bornite ± covellite ± galena ± sphalerite and in invisible form as well. The molybdenite mineralization is predominantly associated with Bundelkhand Tectonic Zone, Raksa Shear Zone, and localized shear zones. The incidence of molybdenite is also observed within sheared quartz and tonalite-trondhjemite-granodiorite (TTG) gneisses. The fluid inclusion data show the presence of bi-phase (H2O-CO2), hypersaline and moderate temperature (100°-300°C) primary stretched fluid inclusions suggesting a possible hydrothermal origin for the Mo-bearing quartz occurring within variably deformed different granitoids variants of Archean Bundelkhand craton.

  5. Hydrothermal Chemotrophic Biosignatures on Mars

    NASA Astrophysics Data System (ADS)

    Westall, F.; Campbell, K. A.; Gautret, P.; Bréhéret, J.; Foucher, F.; Vago, J.; Kminek, G.; Hubert, A.; Hickman-Lewis, K.; Cockell, C. S.

    2016-05-01

    Hydrothermal chemotrophic biosignatures (morphological and geo-organochemical) were common in shallow water on the anaerobic early Earth, preserved by silicification. They are representative also of shallow crustal biosignatures.

  6. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, Bhushan L.

    1995-01-01

    An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the door or wall of the muffle is also provided for controlling the source of optical energy. The quartz for the diffuser plate is surface etched (to give the quartz diffusive qualities) in the furnace during a high intensity burn-in process.

  7. 21 CFR 880.6980 - Vein stabilizer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Vein stabilizer. 880.6980 Section 880.6980 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Miscellaneous Devices § 880.6980 Vein stabilizer. (a)...

  8. Who Is at Risk for Varicose Veins?

    MedlinePlus

    ... risk for varicose veins, including family history, older age, gender, pregnancy, overweight or obesity , lack of movement, and leg trauma. Family History Having family members who have varicose veins may ... of them. Older Age Getting older may raise your risk for varicose ...

  9. [Aneurysm of the femoral and popliteal vein].

    PubMed

    Hansen, L G; Boris, P

    1986-04-01

    Aneurysms of the popliteal and femoral veins are rare and may be seen as casual findings with no clinical manifestations whatsoever. On the other hand they may be potential source of recurrent pulmonary embolism. A case is reported, where an aneurysm of the femoral vein was found in a clinically symptomless woman aged 48. PMID:3715020

  10. [Pseudotumor aspect of ovarian vein thrombosis].

    PubMed

    Randoux, B; Goudot, D; Clément, O; Deux, J F; Lecuru, F; Taurelle, R; Frija, G

    1997-11-01

    Ovarian vein thrombosis is an unusual puerperal illness (1 in 600 deliveries) which usually recovers spontaneously or under treatment. We report a rare follow-up observation of a puerperal ovarian vein thrombophlebitis, first diagnosed by computed tomography, which evolved to a 6 x 10 cm pseudotumoral cavernoma mass after 18 months. PMID:9499957

  11. Pancreatic pseudocyst rupture into the portal vein.

    PubMed

    Dawson, Brian C; Kasa, David; Mazer, Mark A

    2009-07-01

    A patient with a pancreatic pseudocyst rupture into the portal vein with a resultant noninfectious systemic inflammatory response syndrome and subsequent portal vein thrombosis diagnosed by computed tomography and ultrasonography is reported. A review of the existing English literature on this rare complication is also provided. PMID:19561436

  12. Epidemiology of Blackberry yellow vein associated virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Blackberry yellow vein disease is one of the most important diseases of blackberry in the United States. Several viruses are found associated with the symptomology but Blackberry yellow vein associated virus (BYVaV) appears to be the most prevalent of all, leading to the need for a better understand...

  13. Recombinant Human Elastase Treatment of Cephalic Veins

    PubMed Central

    Wong, Marco D; Bingham, Karen; Moss, Emma; Warn, J Donald; Smirnov, Igor; Bland, Kimberly S; Starcher, Barry; Franano, F Nicholas; Burke, Steven K

    2016-01-01

    Background Vessel injury at the time of Arteriovenous Fistula (AVF) creation may lead to neointimal hyperplasia that impairs AVF maturation. Vonapanitase, a recombinant human chymotrypsin-like elastase family member 1, is an investigational drug under development to improve AVF maturation and patency. The current studies were designed to document vonapanitase effects in human cephalic veins that are used in AVF creation. Methods Human cephalic veins were mounted on a perfusion myograph. Vonapanitase 1.2, 4, 13.2, and 40 μg/ml or saline was applied drop wise on the vein followed by saline rinse. Vein segments were cut into rings for elastin content determination by desmosine radioimmunoassay and histology. Fluorescently-labelled vonapanitase was applied to veins and adventitial imaging was performed using laser scanning confocal microscopy. In vivo time course experiments were performed by treating rabbit jugular veins and harvesting 1 h and 4 h after vonapanitase treatment. Results / Conclusion Vonapanitase reduced desmosine content in a dose-related manner. Histology also confirmed a dose-related reduction in elastic fiber staining. Fluorescently-labelled vonapanitase persistently localized to elastic fibers in the vein adventitia. In vivo experiments showed a reduction in desmosine content in jugular veins from 1 h to 4 h following treatment. These data suggest that vonapanitase targets elastin in elastic fibers in a dose related manner and that elastase remains in the vessel wall and has catalytic activity for at least 1 h.

  14. Silica Transport and Cementation in Quartz Aggregates

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    Silica transport and cementation in quartz aggregates have been experimentally investigated. Starting materials include a natural quartz arenite (Pocono sandstone), sized clasts of synthetic quartz, and sized grains of disaggregated natural sandstones. Experimental charges consisted of amorphous silica powder (~25 mg), AlCl3 powder (~3 mg), 25 wt% NaCl brine solution (~20 mg), and the starting material (~150 mg). The charges were weld-sealed in gold capsules and run in cold-seal pressure vessels at 300°C to 600°C at 150 MPa confining pressure for up to 4 weeks. Detailed calibrations of the furnaces indicate the maximum temperature variation across the length of the sample charges (3-7mm) was <5°C, and typically <3°C. After the experiments, samples were vacuum impregnated with epoxy containing a blue dye and sawn in half along the long axis of the sample charge. The nature and amount of silica transport and cementation in the samples was determined by a combination of Cathodoluminescence (CL), Light Microscopy (LM), and Scanning Electron Microscopy (SEM). Photomosaics of the samples were collected and the amount of cement, porosity, and average grain sizes were determined by point-counting. The cement was easily recognized from the quartz grains by the difference in luminescence. The experiments indicate that the presence of amorphous silica results in rapid silica cementation in quartz aggregates (e.g., up to 12% cement by volume in 4 weeks at 450°C). The amount of cementation is a function of substrate type, time, temperature, and ionic strength of the brine. The rate of silica transport through the length of the experimental charge appears to be limited by the silica solubility and its rapid depletion by cementation. Although most of the cement was derived from the amorphous silica, evidence for local dissolution-precipitation was observed. The experiments demonstrate that the mobility of silica, and consequent precipitation of cement, does not require a

  15. Mineral potential tracts for polymetallic Pb-Zn-Cu vein deposits (phase V, deliverable 71): Chapter I in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

    USGS Publications Warehouse

    Beaudoin, Georges

    2015-01-01

    In Mauritania, mineral occurrences of the polymetallic Pb-Zn-Cu vein deposit type are found near the Florence-El Khdar shear zone in northeast Mauritania. The deposits visited were deemed representative of other similar occurrences and consist of quartz veins with trace sulfides. The low sulfide and Pb-Zn-Cu content in the quartz veins is unlike producing polymetallic Pb-Zn-Cu vein deposits, such that the veins are not considered to belong to this deposit type. Mineral potential tracts for polymetallic Pb-ZnCu veins are highly speculative considering the lack of known mineralization belonging to this deposit type. Mineral potential tracts for polymetallic Pb-Zn-Cu veins are associated with and surround major shear zones in the Rgueïbat Shield and zones of complex faulting in the southern Mauritanides, at the exclusion of the imbricated thrust faults that are not considered favorable for this deposit type. No skarn and replacement deposits have been documented in Mauritania and the low mineral potential is indicated by lack of causative Mesozoic and Cenozoic mafic to felsic stocks.

  16. Vein graft in stapes surgery.

    PubMed

    Kamal, S A

    1996-03-01

    Sealing the opening of the oval window during stapes surgery is essential; it prevents postoperative complications, such as perilymph fistula and sensorineural hearing loss. In this small series of 269 cases with otosclerosis, tympanosclerosis, and congenital ossicular abnormality, vein grafting was used to seal the opening of the footplate. Hearing improvement after surgery was acceptable, and none had total hearing loss or perilymphatic fistula. World literature from the last half of this century on grafting the oval window is reviewed. Absorbable gelatin sponge (Gelfoam) seems to be causing more complications, so its use is highly discouraged. Temporalis fascia, fat, and perivenous loose areolar tissue have been used by different authors at different times in footplate surgery. The opening created in the oval window during stapes surgery must not be left uncovered. PMID:8723953

  17. Phlebectasia of Internal Jugular Vein

    PubMed Central

    Bindal, Satish K.; Vasisth, Gaurav O. P.; Chibber, Puneet

    2012-01-01

    Internal jugular phlebectasia (IJP) is a rare disease in which there is a fusiform dilatation of internal jugular vein, usually presenting as a neck mass in children. Accurate diagnosis from careful history, physical examination, and radiological study can be made. We report a 12-year-old boy with history of swelling appearing on the right side of the neck only on straining, coughing, or during a Valsalva maneuver. Diagnosis of right IJP was made. Exploration and wrapping the dilated segment in an 8-mm-diameter polytetrafluoroethylene tube graft was done. Because of its rarity, this entity is frequently ignored or misdiagnosed. This case report intends to stress the importance of keeping IJP as differential diagnosis while dealing with such a swelling to avoid invasive investigations and inappropriate treatment. PMID:23741586

  18. Retinal vein occlusion: current treatment.

    PubMed

    Lattanzio, Rosangela; Torres Gimeno, Ana; Battaglia Parodi, Maurizio; Bandello, Francesco

    2011-01-01

    Retinal vein occlusion (RVO) is a pathology noted for more than 150 years. Although a lot has been written on the matter, it is still a frequent condition with multifactorial etiopathogenesis with many unclear aspects. The RVO pathogenesis has varied systemic and local implications that make it difficult to elaborate treatment guidelines. The management of the patient with RVO is very complex and a multidisciplinary approach is required in order to identify and correct the associated risk factors. Laser therapy remains the gold standard in RVO, but only modest functional improvement has been shown in branch retinal occlusion forms. Multicenter studies of intravitreal drugs present them as an option to combine with laser. Anti-vascular endothelial growth factor, corticosteroids and sustained-release implants are the future weapons to stop disease progression and get a better visual outcome. Consequently, it is useful to clarify some aspects of the pathology that allow a better patient management. PMID:20938213

  19. Treatment of deep vein thrombosis

    PubMed Central

    Douketis, James D.

    2005-01-01

    OBJECTIVE To identify patients with deep vein thrombosis (DVT) for whom in-hospital treatment should be considered. QUALITY OF EVIDENCE The literature was searched for studies on outpatient treatment of DVT. Seventeen studies were assessed: seven were randomized controlled trials (level I evidence), and 10 were non-randomized trials (level II evidence). MAIN MESSAGE Four criteria can be used to identify patients with DVT for whom outpatient treatment might not be appropriate: presence of massive DVT, presence of symptomatic pulmonary embolism, high risk of bleeding with anticoagulant therapy, and presence of comorbid conditions or other factors that warrant in-hospital care. CONCLUSION Four criteria can be used to identify patients with DVT for whom in-hospital treatment should be considered. PMID:15751565

  20. Enhancing the contrast of subcutaneous veins

    NASA Astrophysics Data System (ADS)

    Zeman, Herbert D.; Lovhoiden, Gunnar

    1999-07-01

    A technique for enhancing the contrast of subcutaneous veins has been demonstrated. This technique uses a near infrared light source and one or more infrared sensitive CCD TV cameras to produce a contrast enhanced image of the subcutaneous veins. This video image of the veins is projected back onto the patient's skin using an LCD vein projector. The use of an infrared transmitting filter in front of the video cameras prevents any positive feedback from the visible light from the video projector from causing instabilities in the projected image. The demonstration contrast enhancing illuminator has been tested on adults, both Caucasian and African-American, and it enhances veins quite well in most cases. Preliminary studies on a 9 month old girl indicate promise for pediatric use.

  1. Guide wire migration during femoral vein catheterization.

    PubMed

    Khatami, Mohammad Reza; Abbasi, Rozita; Sadigh, Gelareh

    2010-10-01

    Central vein catheterization is a routine and relatively safe procedure in critically ill patients. Complications with this procedure depend to the site of catheterization and the skill of the operator. In addition to the common complications with femoral vein catheterization there are some rare usually preventable side effects related to guide wire and catheter. In our patient who underwent femoral catheterization for acute hemodialysis, we report migration of guide wire through the systemic circulation from the femoral vein to the jugular vein. This is a very rare complication that is a human error and is totally preventable by doing the procedure by a skilled doctor and considering the standards described for central vein catheter insertion. PMID:20852377

  2. Adventitial cystic disease of common femoral vein

    PubMed Central

    Suh, Bo-Yang

    2011-01-01

    Adventitial cystic disease (ACD) of venous system is an extremely rare condition. Very few reports of ACD in venous system have been described. In this report we discuss two cases of common femoral vein ACD that presented with a swollen leg by the obstruction of the vein. Ultrasound imaging showed the typical hypoechoic fluid filled cyst with a posterior acoustic window. Computed tomography scan and ascending venogram showed a stenosis to flow in the common femoral vein caused by an extrinsic mass. Trans-adventitial evacuation of cyst with removal of vein wall was performed for both cases. During operation we found the gelatinous material in the cysts arising in the wall of the common femoral vein and compressing the lumen. The patients were released after short hospitalization and have remained symptom free with no recurrence. PMID:22066091

  3. Upper extremity deep vein thrombosis

    PubMed Central

    Saseedharan, Sanjith; Bhargava, Sunil

    2012-01-01

    A 56-year-old female, recently (3 months) diagnosed with chronic kidney disease (CKD), on maintenance dialysis through jugular hemodialysis lines with a preexisting nonfunctional mature AV fistula made at diagnosis of CKD, presented to the hospital for a peritoneal dialysis line. The recently inserted indwelling dialysis catheter in left internal jugular vein had no flow on hemodialysis as was the right-sided catheter which was removed a day before insertion of the left-sided line. The left-sided line was removed and a femoral hemodialysis line was cannulated for maintenance hemodialysis, and the next day, a peritoneal catheter was inserted in the operation theater. However, 3 days later, there was progressive painful swelling of the left hand and redness with minimal numbness. The radial artery pulsations were felt. There was also massive edema of forearm, arm and shoulder region on the left side. Doppler indicated a steal phenomena due to a hyperfunctioning AV fistula for which a fistula closure was done. Absence of relief of edema prompted a further computed tomography (CT) angiogram (since it was not possible to evaluate the more proximal venous segments due to edema and presence of clavicle). Ct angiogram revealed central vein thrombosis for which catheter-directed thrombolysis and venoplasty was done resulting in complete resolution of signs and symptoms. Upper extremity DVT (UEDVT) is a very less studied topic as compared to lower extremity DVT and the diagnostic and therapeutic modalities still have substantial areas that need to be studied. We present a review of the present literature including incidences, diagnostic and therapeutic modalities for this entity. Data Sources: MEDLINE, MICROMEDEX, The Cochrane database of Systematic Reviews from 1950 through March 2011. PMID:22624098

  4. What Are the Signs and Symptoms of Deep Vein Thrombosis?

    MedlinePlus

    ... Twitter. What Are the Signs and Symptoms of Deep Vein Thrombosis? The signs and symptoms of deep vein thrombosis ( ... serious, possibly life-threatening problems if not treated. Deep Vein Thrombosis Only about half of the people who have ...

  5. Authigenic quartz in the Upper Freeport coalbed, west- central Pennsylvania

    SciTech Connect

    Ruppert, L.P.

    1985-05-01

    Cathodoluminescence petrography was used to examine quartz grains contained in facies of the Upper Freeport coalbed (Middle Pennsylvanian) of west-central Pennsylvania. Samples included ash concentrates, polished blocks of different lithotypes, and standard petrographic pellets of specific gravity separates of facies channel samples. More than 80% of the quartz in mineral and vitrain-rich bands in the polished blocks do not exhibit cathodoluminescence. In specific gravity separates, 100% of the quartz in the lightest gravity separates did not luminesce. In the heaviest gravity separates, which included shale-parting material, 60% of the quartz did not luminesce. In contrast, in a sample of shale directly overlying the coalbed, more than 90% of the quartz luminesced. On the basis of these data and of other published data, quartz in the Upper Freeport coalbed is interpreted to be authigenic in origin. The authigenic quartz grains are postulated to have been derived from phytoclasts.

  6. [SUBFASCIAL ENDOSCOPIC PERFORATOR VEIN SURGERY IN THE TREATMENT OF SEVERE VARICOSE VEINS].

    PubMed

    Tabuchi, Atsushi; Masaki, Hisao; Tanemoto, Kazuo

    2015-05-01

    Surgical treatment of severe varicose veins (CEAP classification : C4b-C6) should involve not only interruption of incompetent superficial veins to prevent venous regurgitation due to valve incompetence but also interruption of incompetent perforator veins. Subfascial endoscopic perforator vein surgery (SEPS) is performed via a small skin incision and involves interruption of perforator veins by the insertion of an endoscope into the subfascial space. SEPS produces good surgical outcomes: it is accurate in detecting and transecting perforator veins; has a low frequency of surgical wound complications; prevents lipodermatosclerosis and formation of pigmented skin lesions; and is minimally invasive compared with Linton's operation. Thus, SEPS is an excellent procedure for patients with incompetent perforator veins. SEPS has been covered by the Japanese national health insurance system since April 2014, and it is expected that SEPS will be further developed and become more widespread in use. PMID:26281656

  7. Hydrothermal vents is Lake Tanganyika, East African Rift system

    SciTech Connect

    Tiercelin, J.J.; Pflumio, C.; Castrec, M.

    1993-06-01

    Sublacustrine hydrothermal vents with associated massive sulfides were discovered during April 1987 at Pemba and Cape Banza on the Zaire side of the northern basin of Lake Tanganyika, East African Rift system. New investigations by a team of ten scuba divers during the multinational (France, Zaire, Germany, and Burundi) TANGANYDRO expedition (August-October 1991) found hydrothermal vents down to a depth of 46 m along north-trending active faults bounding the Tanganyika rift on the western side. Temperatures from 53 to 103 {degrees}C were measured in hydrothermal fluids and sediments. Veins of massive sulfides 1-10 cm thick (pyrite and marcasite banding) were found associated with vents at the Pemba site. At Cape Banza, active vents are characterized by 1-70-cm-high aragonite chimneys, and there are microcrystalline pyrite coatings on the walls of hydrothermal pipes. Hydrothermal fluid end members show distinctive compositions at the two sites. The Pemba end member is a NaHCO{sub 3}-enriched fluid similar to the NaHCO{sub 3} thermal fluids form lakes Magadi and Bogoria in the eastern branch of the rift. The Cape Banza end member is a solution enriched in NaCl. Such brines may have a deep-seated basement origin, as do the Uvinza NaCl brines on the eastern flank of the Tanganyika basin. Geothermometric calculations have yielded temperatures of fluid-rock interaction of 219 and 179 {degrees}C in the Pemba and Cape Banza systems, respectively. Abundant white or reddish-brown microbial colonies resembling Beggiatoa mats were found surrounding the active vents. Thermal fluid circulation is permitted by opening of cracks related to 130{degrees}N normal-dextral faults that intersect the north-south major rift trend. The sources of heat for such hydrothermal systems may relate to the existence of magmatic bodies under the rift, which is suggested by the isotopic composition of carbon dioxide released at Pemba and Cape Banza. 21 refs., 2 figs.

  8. Cyclic development of igneous features and their relationship to high-temperature hydrothermal features in the Henderson porphyry molybdenum deposit, Colorado

    USGS Publications Warehouse

    Carten, R.B.; Geraghty, E.P.; Walker, B.M.

    1988-01-01

    The Henderson porphyry molybdenum deposit was formed by the superposition of coupled alteration and mineralization events, of varying intensity and size, that were associated with each of at least 11 intrusions. Deposition of molybdenite was accompanied by time-equivalent silicic and potassic alteration. High-temperature alteration and mineralization are spatially and temporally linked to the crystallization of compositionally zoned magma in the apex of stocks. Differences in hydrothermal features associated with each intrusion (e.g., mass of ore, orientation and type of veins, density of veins, and intensity of alteration) correlate with differences in primary igneous features (e.g., composition, texture, morphology, and size). The systematic relations between hydrothermal and magmatic features suggest that primary magma compositions, including volatile contents, largely control the geometry, volume, level of emplacement, and mechanisms of crystallization of stocks. These elements in turn govern the orientations and densities of fractures, which ultimately determine the distribution patterns of hydrothermal alteration and mineralization. -from Authors

  9. Quartz deformation mechanisms during Barrovian metamorphism: Implications from crystallographic orientation of different generations of quartz in pelites

    NASA Astrophysics Data System (ADS)

    Rahimi-Chakdel, A.; Boyle, A. P.; Prior, D. J.

    2006-12-01

    The behaviour of quartz during metamorphism is studied based on two case studies from the Barrovian terrains of Sulitjelma in arctic Scandinavia and Loch Tay in the Central Highlands Dalradian of Scotland. Both terrains preserve evidence for metamorphism in pelites involving nucleation and growth of garnet at different times in the deformation history. Data are presented on the size, shape and crystallographic orientation of quartz preserved as inclusions in garnet and as grains in the surrounding matrix. While quartz-grains remain small and dispersed between mica grains, deformation appears to be dominated by grain-boundary sliding accommodated by dissolution-precipitation. At amphibolite facies, textural coarsening occurs by dissolution of small quartz grains and growth of larger quartz grains, coupled with segregation of quartz from mica. As a result, quartz deforms by dislocation creep, developing crystallographic preferred orientations (CPO) consistent with both coaxial and non-coaxial strain. Quartz CPOs with <0001> axes lying parallel to foliation and stretching direction are commonly developed, and best explained by mechanical rotation of inequant (detrital?) quartz grains. There is no evidence for selective entrapment of quartz inclusions in garnet on the basis of quartz crystallographic orientation.

  10. The umbilical and paraumbilical veins of man.

    PubMed Central

    Martin, B F; Tudor, R G

    1980-01-01

    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. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 Fig. 18 Fig. 19 Fig. 20 Fig. 21 Fig. 22 Fig. 23 Fig. 24 Fig. 25 Fig. 26 Fig. 27 Fig. 28 Fig. 29 PMID:7400038

  11. Conditions for veining in the Barrandian Basin (Lower Palaeozoic), Czech Republic: evidence from fluid inclusion and apatite fission track analysis

    NASA Astrophysics Data System (ADS)

    Suchy, V.; Dobes, P.; Filip, J.; Stejskal, M.; Zeman, A.

    2002-04-01

    The interplay between fracture propagation and fluid composition and circulation has been examined by deciphering vein sequences in Silurian and Devonian limestones and shales at Kosov quarry in the Barrandian Basin. Three successive vein generations were recognised that can be attributed to different stages of a basinal cycle. Almost all generations of fracture cements host abundant liquid hydrocarbon inclusions that indicate repeated episodes of petroleum migration through the strata during burial, tectonic compression and uplift. The earliest veins that propagated prior to folding were displacive fibrous "beef" calcite veins occurring parallel to the bedding of some shale beds. Hydrocarbon inclusions within calcite possess homogenisation temperatures between 58 and 68 °C and show that the "beef" calcites originated in the deeper burial environment, during early petroleum migration from overpressured shales. E-W-striking extension veins that postdate "beef" calcite formed in response to Variscan orogenic deformations. Based on apatite fission track analysis (AFTA) data and other geological evidence, the veins probably formed 380-315 Ma ago, roughly coinciding with peak burial heating of the strata, folding and the intrusion of Variscan synorogenic granites. The veins that crosscut diagenetic cements and low-amplitude stylolites in host limestones are oriented semi-vertically to the bedding plane and are filled with cloudy, twinned calcite, idiomorphic smoky quartz and residues of hardened bitumen. Calcite and quartz cements contain abundant blue and blue-green-fluorescing primary inclusions of liquid hydrocarbons that homogenise between 50 and 110 °C. Geochemical characteristics of the fluids as revealed by gas chromatography-mass spectrometry, particularly the presence of olefins and parent aromatic hydrocarbons (phenonthrene), suggest that the oil entrapped in the inclusions experienced intense but geologically fast heating that resulted in thermal pyrolysis

  12. Probing Hydrothermal Organic Reaction Mechanisms with Hydrothermal Photochemistry

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Gould, I.; Shock, E.

    2013-12-01

    In most hydrothermal organic experiments the emphasis is on reaction product distributions and kinetic measurements, with mechanistic information or the direct evidence of proposed reaction intermediates rare or lacking. We believe that greater mechanistic insight will yield greater predictive power. Previously, we studied the reactions of a model ketone, dibenzylketone (DBK) in aqueous media at 300°C and 700 bars for durations up to several days [1], and found that many of the reaction products arise from coupling of benzyl and related radicals generated through homolytic bond cleavage of DBK. In the present work, we find that in situ photochemical generation of the radicals can provide independent evidence for radical intermediates in the hydrothermal reaction of DBK, yielding valuable insights into the thermal reactions. Hydrothermal photochemical experiments of DBK were conducted in water in sealed fused silica glass tubes at 300°C and 86 bars under UV irradiation for minutes. The short timescale of the experiments allows the primary radical coupling products of DBK to be generated and identified, and their follow-up reactions to be monitored directly. The primary hydrothermal photolysis products include toluene, bibenzyl, a three-benzene-ring product (with isomers), and two four-benzene-ring products (with isomers), which represent a much simpler version of the products obtained through thermal reactions under similar conversions. Most of the observed photolysis products were identical to the ones in the thermal reactions, and those not observed in thermal reactions were found to be the short-lived precursors of the thermal products. As an example, the transformation of one four-ring product to the other was attained and monitored by experiments in which hydrothermal photolysis of DBK was followed by thermolysis at 300°C for a further few hours. The transformation steps included dehydration and isomerization, which were known to be thermodynamically

  13. Hydrothermal fluids responsible for the formation of precious minerals in the Nigerian Younger Granite Province

    NASA Astrophysics Data System (ADS)

    Abaa, S. I.

    1991-04-01

    Preliminary investigations in the Younger Granite Province of Nigeria have revealed that precious and semi-precious minerals like rubies, sapphires, emeralds, aquamarine, zircon and fluorite can be found in the region. The gem minerals are shown to have been produced either by direct deposition along fissures, veins and greisens by hydrothermal fluids or as a result of hydrothermal fluids reacting with wall-rocks. These wall rocks are either biotite granites from which the hydrothermal fluids originated or basement rocks or any other rocks which the biotite granites intrude and their residual hydrothermal fluids have invaded. The hydrothermal fluids appear to have been rich in alkalis (Na+, K+, etc.), rare elements (Be, Zr, F, REE, etc.) and siliceous. As these fluids rose through fractures and channel ways through the rocks, they either deposited the gem minerals in the fractures at the appropriate stability conditions or reacted with the wall-rocks producing the gem minerals at the expense of elements like Ca and A1 in the minerals of these rocks.

  14. Oxygen and carbon isotope ratios of hydrothermal minerals from Yellowstone drill cores

    USGS Publications Warehouse

    Sturchio, N.C.; Keith, T.E.C.; Muehlenbachs, K.

    1990-01-01

    Oxygen and carbon isotope ratios were measured for hydrothermal minerals (silica, clay and calcite) from fractures and vugs in altered rhyolite, located between 28 and 129 m below surface (in situ temperatures ranging from 81 to 199??C) in Yellowstone drill holes. The purpose of this study was to investigate the mechanism of formation of these minerals. The ??18O values of the thirty-two analyzed silica samples (quartz, chalcedony, ??-cristobalite, and ??-cristobalite) range from -7.5 to +2.8???. About one third of the silica 7samples have ??18O values that are consistent with isotopic equilibrium with present thermal waters; most of the other silica samples appear to have precipitated from water enriched in 18O (up to 4.7???) relative to present thermal water, assuming precipitation at present in situ temperatures. Available data on fluid-inclusion homogenization temperatures in hydrothermal quartz indicate that silica precipitation occurred mostly at temperatures above those measured during drilling and imply that 15O enrichments in water during silica precipitation were generally larger than those estimated from present conditions. Similarly, clay minerals (celadonite and smectite) have ??18O values higher (by 3.5 to 7.9???) than equilibrium values under present conditions. In contrast, all eight analyzed calcite samples are close to isotopic equilibrium with present thermal waters. The frequent incidence of apparent 18O enrichment in thermal water from which the hydrothermal minerals precipitated may indicate that a higher proportion of strongly 18O-enriched deep hydrothermal fluid once circulated through shallow portions of the Yellowstone system, or that a recurring transient 18O-enrichment effect occurs at shallow depths and is caused either by sudden decompressional boiling or by isotopic exchange at low water/rock ratios in new fractures. The mineralogy and apparent 18O enrichments of hydrothermal fracture-filling minerals are consistent with deposition

  15. Fluid source and pressure temperature conditions of high-salinity fluids in syn-tectonic veins from the Northeastern Apuan Alps (Northern Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Montomoli, Chiara; Ruggieri, Giovanni; Carosi, Rodolfo; Dini, Andrea; Genovesi, Marianna

    Structural studies on syn-tectonic veins cropping out in the northeastern sector of the Apuan Alps metamorphic complex (Northern Apennines, Italy) revealed two sets of veins: (1) type A fibrous veins within the “Scisti sericitici Formation”, related to a late-D1 tectonic phase; (2) B-veins, within the “Diaspri Formation” that developed between late-D1 and D2 tectonic phases. The mineralogy of the A (quartz, chlorite, hematite with minor amounts of apatite, allanite-(Ce), thorite and synchysite) and B-veins (quartz only) reflects the mineralogical composition of the host-rocks: quartz, chlorite, white mica and accessory minerals (apatite, zircon, titanite) occur in the “Scisti sericitici Formation”, while quartz is the main phase in the “Diaspri Formation”. The study of fluid inclusions trapped in quartz crystals of the syn-tectonic veins shows that the inclusions are always oversaturated in NaCl at room temperature and their salinities range from 29.5 to 37 wt.% NaCl equiv. The isochore of the earliest trapped fluid inclusions (type IA; primary inclusions in fiber quartz of A veins), coupled with mineralogical geothermometric data, constrains the pressure-temperature conditions to around 325-300 MPa and 370-380 °C during the late-D1 phase. Subsequent trapping of inclusion types IIA, IIB, IIIA, IIIB and VB in the two vein sets probably occurred during a pressure-temperature decrease (down to 220-245 MPa and 260-270 °C) at a lithostatic thermal gradient of 30 °C/km. Type IVB inclusions, on the other hand, were probably trapped at lower pressure (between lithostatic and hydrostatic conditions) during a transient pressure drop resulting from fault-valve action. SEM/EDS analyses on salts precipitated within opened inclusions confirmed the NaCl-rich compositions of the trapped fluids and also revealed the presence of minor amounts of Ca, K and Mn in the salts. A fluid circulation model, based on mineralogical and fluid inclusion data, was proposed for

  16. Kinetics of the coesite to quartz transformation

    USGS Publications Warehouse

    Mosenfelder, J.L.; Bohlen, S.R.

    1997-01-01

    The survival of coesite in ultrahigh-pressure (UHP) rocks has important implications for the exhumation of subducted crustal rocks. We have conducted experiments to study the mechanism and rate of the coesite ??? quartz transformation using polycrystalline coesite aggregates, fabricated by devitrifying silica glass cylinders containing 2850H/106 Si at 1000??C and 3.6 GPa for 24h. Conditions were adjusted following synthesis to transform the samples at 700-1000??C at pressures 190-410 MPa below the quartz-coesite equilibrium boundary. Reaction proceeds via grain-boundary nucleation and interface-controlled growth, with characteristic reaction textures remarkably similar to those seen in natural UHP rocks. We infer that the experimental reaction mechanism is identical to that in nature, a prerequisite for reliable extrapolation of the rate data. Growth rates obtained by direct measurement differ by up to two orders of magnitude from those estimated by fitting a rate equation to the transformation-time data. Fitting the rates to Turnbull's equation for growth therefore yields two distinct sets of parameters with similar activation energies (242 or 269 kJ/mol) but significantly different pre-exponential constants. Extrapolation based on either set of growth rates suggests that coesite should not be preserved on geologic time scales if it reaches the quartz stability field at temperatures above 375-400??C. The survival of coesite has previously been linked to its inclusion in strong phases, such as garnet, that can sustain a high internal pressure during decompression. Other factors that may play a crucial role in preservation are low fluid availability - possibly even less than that of our nominally "dry" experiments - and the development of transformation stress, which inhibits nucleation and growth. These issues are discussed in the context of our experiments as well as recent observations from natural rocks. ?? 1997 Elsevier Science B.V.

  17. Personal authentication through dorsal hand vein patterns

    NASA Astrophysics Data System (ADS)

    Hsu, Chih-Bin; Hao, Shu-Sheng; Lee, Jen-Chun

    2011-08-01

    Biometric identification is an emerging technology that can solve security problems in our networked society. A reliable and robust personal verification approach using dorsal hand vein patterns is proposed in this paper. The characteristic of the approach needs less computational and memory requirements and has a higher recognition accuracy. In our work, the near-infrared charge-coupled device (CCD) camera is adopted as an input device for capturing dorsal hand vein images, it has the advantages of the low-cost and noncontact imaging. In the proposed approach, two finger-peaks are automatically selected as the datum points to define the region of interest (ROI) in the dorsal hand vein images. The modified two-directional two-dimensional principal component analysis, which performs an alternate two-dimensional PCA (2DPCA) in the column direction of images in the 2DPCA subspace, is proposed to exploit the correlation of vein features inside the ROI between images. The major advantage of the proposed method is that it requires fewer coefficients for efficient dorsal hand vein image representation and recognition. The experimental results on our large dorsal hand vein database show that the presented schema achieves promising performance (false reject rate: 0.97% and false acceptance rate: 0.05%) and is feasible for dorsal hand vein recognition.

  18. Spherical quartz crystals investigated with synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Pereira, N. R.; Macrander, A. T.; Hill, K. W.; Baronova, E. O.; George, K. M.; Kotick, J.

    2015-10-01

    The quality of x-ray spectra and images obtained from plasmas with spherically bent crystals depends in part on the crystal's x-ray diffraction across the entire crystal surface. We employ the energy selectivity and high intensity of synchrotron radiation to examine typical spherical crystals from alpha-quartz for their diffraction quality, in a perpendicular geometry that is particularly convenient to examine sagittal focusing. The crystal's local diffraction is not ideal: the most noticeable problems come from isolated regions that so far have failed to correlate with visible imperfections. Excluding diffraction from such problem spots has little effect on the focus beyond a decrease in background.

  19. Spherical quartz crystals investigated with synchrotron radiation.

    PubMed

    Pereira, N R; Macrander, A T; Hill, K W; Baronova, E O; George, K M; Kotick, J

    2015-10-01

    The quality of x-ray spectra and images obtained from plasmas with spherically bent crystals depends in part on the crystal's x-ray diffraction across the entire crystal surface. We employ the energy selectivity and high intensity of synchrotron radiation to examine typical spherical crystals from alpha-quartz for their diffraction quality, in a perpendicular geometry that is particularly convenient to examine sagittal focusing. The crystal's local diffraction is not ideal: the most noticeable problems come from isolated regions that so far have failed to correlate with visible imperfections. Excluding diffraction from such problem spots has little effect on the focus beyond a decrease in background. PMID:26520963

  20. Environmental sensitivities of quartz crystal oscillators

    NASA Technical Reports Server (NTRS)

    Walls, Fred L.

    1990-01-01

    The frequency, amplitude, and noise of the output signal of a quartz crystal controlled oscillator is affected by a large number of environmental effects. The physical basis for the sensitivity of precision oscillators to temperature, humidity, pressure, vibration, magnetic field, electric field, load, and radiation is discussed. The sensitivity of crystal oscillators to radiation is a very complex topic and poorly understood. Therefore only a few general results are mentioned. The sensitivity to most external influences often varies significantly from one oscillator type t