Sample records for hydrothermal quartz veins

  1. 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.

  2. 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 result would be the first indication for pre-biotic organic chemistry. In contrast, almost no organic compounds have been detected inside fluid inclusions from impact-generated quartz veins of the Shoemaker-Crater (its geological age is estimated between 1.6 and 1.0 Ga), even though they partially have formed in stromatolite-bearing sedimentary rocks. Some of them occur in Precambrian gneisses. We interpret the absence of organic compounds as a consequence of the different genesis of the quartzes near the Shoemaker-crater: the impact-induced hydrothermal system had no connection to the Earth's mantle and hence, no contact to rising volcanic fluids. Our analytical results prove the presence of complex organic molecules in fluid inclusions trapped in quartz veins from the Archaean Yilgarn craton in Australia. They allow a more detailed understanding of the synthetic processes which have occurred in rising hydrothermal fluids in the upper crust of the earth and which may have led to the formation of early pre-biotic organic molecules. Based on the findings, laboratory experiments will be designed to reproduce these processes and to yield further understanding on their mechanism. Furthermore, they should yield a collection of possible products which may have formed the basis for the first biomolecules in Earth's history.

  3. 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 ?13C- and ?2H-values of CH4 were measured by GC-IRMS to examine if the detected organic compounds are formed biotic, thermogenic or abiotic, and to investigate the relationship between aquifer rocks and FIs. Our results add new information to the evolution of FIs in hydrothermal systems and the potential role of hydrothermal fluids to the origin of life [6]. [1] Mulder et al., 2013 Chem. Geol., 358: 148-155 [2] Kirnbauer, 1998, Geologie und hydro-thermale Mineralisationen im rechtsrheinischen Schiefergebirge. - 328 pp [3] Kirnbauer et al., 2012, Ore Geol. Reviews, 48: 239-257. [4] Jordan, 2003, Handbook of Environmental Chemistry, Vol. 3, Part P: 121-139 [5] Schöler & Keppler, 2003 Handbook of Environ-mental Chemistry, Vol. 3, Part P: 63-84; [6] Schreiber et al., 2012 Origins of Life and Evolution of Biosphere, 42: 47-54.

  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 simulations, we study the sealing of syntaxial veins of 300 microns aperture by epitaxial overgrowth of preexisting grains from the rock surface. Results from 3D simulations conducted in the limit of low Damköhler numbers explain the observed transition regime in competitive crystal growth for blocky-elongate veins. The initial formation of quartz crystal bridges, especially pronounced in the regime of low supersaturation, is observed. The morphological evolution of micro-ensembles of grain neighbourhoods from the rock sample compares well to that of the simulations. To juxtapose larger polycrystal domains, the variation of grain number, texture and porosity as function of scaled distance from the initial wall is calculated. Velocity profiles from solutions of the isothermal incompressible Navier-Stokes equation are used to record permeability evolution and to evaluate deviations from the cubic law. Both, the geometry of the microstructure and the permeability of the flow pathway, are used as upscaling parameters for larger scale (fracture scale) simulations.

  5. Hydrothermal Synthesis of Quartz Nanocrystals

    E-print Network

    conditions where bulk quartz is known to precipitate from aqueous solutions saturated with silica mechanisms responsible for solid-state amorphization and the R- transition, and their solution phase applications motivated us to develop a solution-phase route to form nanoquartz. Quartz possesses features

  6. Scanning electron microscope cathodoluminescence analysis of quartz reveals complex growth histories in veins from the Butte porphyry copper deposit, Montana

    Microsoft Academic Search

    Brian Rusk; Mark Reed

    2002-01-01

    Scanning electron microscope cathodoluminescence (SEM-CL) analysis of quartz reveals textures that cannot be observed using optical microscopy or backscattered electrons. These cryptic textures yield insight into timing and physical conditions of quartz growth, especially in environments with multiple quartz-precipitation events. Hydrothermal quartz from quartz-sulfide veins in the porphyry copper deposit in Butte, Montana, was analyzed by SEM-CL, revealing the following

  7. Insights Into the Formation of Deep Hydrothermal Quartz From the Porphyry-Copper- Molybdenum Deposit at Butte, Montana

    Microsoft Academic Search

    C. N. Mercer; M. H. Reed

    2007-01-01

    We combine SEM-cathodoluminescence (SEM-CL) images of magmatic and hydrothermal quartz with trace elements and quartz precipitation temperatures to elucidate the formation of deep quartz veins in a porphyry-style deposit. Trace elements (Ti, K, Al, and Fe) were measured by EPMA along traverses crossing CL textural boundaries and quartz precipitation temperatures were calculated using the Ti in quartz (TitaniQ) geothermometer (Wark

  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 aimed at delineating the area of quartz-molybdenite mineralization, documenting hydrothermal alteration and zonation, determining fracture density, and evaluating the sulfide assemblage.

  9. Investigating the strengthening of quartz ceramics by hydrothermal treatment

    Microsoft Academic Search

    S. M. Itkin; V. V. Vikulin

    1993-01-01

    Increasing application of quartz ceramics is accompanied by an increase in the dimensions of the articles, in the complexity of their shapes, a constant increase in demands placed on dimensional accuracy, and also the need to reduce energy expenditure. As a result of all this, extensive use can be found for precision technology in strengthening the components by hydrothermal treatment

  10. 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 (?18O 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 the cyclic character of quartz growth and perhaps also the changes in Al/Si may be related to pressure variations caused by seismic activity during retrograde Alpine metamorphism. A-L. Jourdan et al. (2009) Mineralogical Magazine, 73, 615-632. R.O. Fournier and R.W. Potter (1982) Geochimica et Cosmochimica Acta, 46, 1969-1973.

  11. Analysis of Rare Earth Elements (REE) in vein quartz and quartz-sandstone host rock in the Zhelannoe high purity quartz deposit, Russia

    NASA Astrophysics Data System (ADS)

    Zemskova, Marina; Prokofiev, Vsevolod; Bychkov, Andrey

    2015-04-01

    The Zhelannoe high purity quartz deposit is located on the western slope of the Polar Urals. It is one of the largest deposits of vein quartz and rock crystal in Russia. Most of the mineralization is hosted within a single horizon of very firm quartz-sandstone, where plastic deformation did not occur almost entirely. All tectonic stress was released by the development of numerous thrust faults of different scales. Cavities formed during this process were later filled with quartz and rock crystal. In order to obtain more details on conditions under which mineralization took place, analysis of trace element contents in vein quartz and host rocks, and the micro-thermometric study of fluid inclusions in quartz have been carried out. The trace element composition of vein quartz and of the host rock has been determined by ICP-MS. The results have shown that concentrations of most of the 46 studied elements in quartz are two orders of magnitude lower than in chondrite, and more than three orders of magnitude lower than in the upper crust. Even though Pb and Li have the highest concentrations in quartz samples, levels are only nearly comparable in chondrite, and substantially lower in the upper crust. At the same time, negative anomalies of Pb and Li concentrations in the host rock may indicate the removal of these elements during vein quartz formation. Contents of most REEs are two orders of magnitude lower than in chondrite, and three orders of magnitude lower than in the host rock. Generally, the patterns of REE distribution in vein quartz and the host rock express a clear correlation; confirming the genetic link between vein quartz and quartz-sandstone host rock. However, the process of quartz recrystallization led to an intense decrease of REEs content, and of all other impurities, which consequently influenced industrial value of the Zhelannoe deposit. As a result of the micro-thermometric study of fluid inclusions in quartz, the following physical-chemical parameters of mineral-forming fluids have been established: homogenization temperature 217 - 159 °C; concentration of salts 9.8 - 5.9 wt. percent NaCl equiv.; density of fluid 980-900 kg/m3; pressure estimates for associations of heterogeneous fluid inclusions vary from 80 - 50 bar. There are two principal types of inclusions: vapor, and two-phase liquid-gas inclusions. The state of mineral-forming fluid is heterogeneous. Carbon dioxide condenses in gaseous inclusions upon cooling. Data on salinity and density of mineral-forming fluids, the presence of the gas phase with carbon dioxide; and estimates of pressure during the formation of quartz of the Zhelannoe deposit have been obtained for the first time.

  12. 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 misoriented for basal slip hardened and deformed predominantly by domainal fracturing. This study indicates the importance of considering shear zones as dynamic systems wherein the activated deformation mechanisms may vary through time in response to the complex temporal and spatial evolution of the shear zone, often in a cyclic fashion.

  13. Geometry and texture of quartz veins in Wadi Atalla area, Central Eastern Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Akawy, Ahmed

    2007-02-01

    Several quartz vein sets with varying orientation, geometry and internal structure were recognized in the Atalla area. The veins were associated with the deformation phases affecting the area. En echelon and extensional veins are the main geometrical types. Syn-kinematic veins associated with the major northeast-over-southwest thrust faults were later boudinaged, folded and re-folded. En echelon veins, fibrous veins, and extensional veins are associated with the NNW-SSE faults. Other veins are associated with the NW-SE, N-S, NE-SW and E-W faults. Veins are concentrated at the intersection zones between faults. The internal structure of the veins comprises syntaxial, antitaxial, and composite types and reflects a change from a compressive stress regime to an extensional one. Chocolate-tablet structures and synchronous and co-genetic vein networks indicate later multi-directional extension of the area. Interaction between cracking and sealing of fractures is a common feature in the study area indicating that it was easy for the pore pressure to open pre-existing fractures instead of creating new ones. The reopening of pre-existing fractures rather than creating new ones is also indicated by the scattering of vein data around ?3. There is an alteration and change in characteristics of the wall rock due to increase in fluid flow rate. Fault-valving probably is also a cause of the complex geometry of some veins.

  14. Trace elements and cathodoluminescence of quartz in stockwork veins of Mongolian porphyry-style deposits

    Microsoft Academic Search

    Axel Müller; Richard Herrington; Robin Armstrong; Reimar Seltmann; Douglas J. Kirwin; Nina G. Stenina; Andreas Kronz

    2010-01-01

    The combination of scanning electron microscope–cathodoluminescence (CL), fluid inclusion analysis and high-resolution electron\\u000a probe microanalysis of Al, Ti, K and Fe in vein quartz has yielded results permitting a greater understanding of the complex\\u000a mineralisation of the Central Oyu Tolgoi and Zesen Uul porphyry-style deposits, southern Mongolia. These data demonstrate\\u000a the relationship between quartz precipitation, dissolution and ore deposition as

  15. 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. [Univ. of Utah, Salt Lake City, UT (United States)

    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.

  16. Compaction of granular quartz under hydrothermal conditions: Controlling mechanisms and grain boundary processes

    Microsoft Academic Search

    Reinier van Noort; Christopher J. Spiers; Gill M. Pennock

    2008-01-01

    We report isostatic compaction experiments performed on granular quartz under hydrothermal conditions (3-129 mum of initial grain size, 300-600°C, 200 MPa of fluid pressure, and 25-100 MPa of effective pressure). From microstructural evidence, it was determined that, whereas microcracking controlled precompaction at room temperature, pressure solution was the main mechanism during hydrothermal compaction, although a role of microcracking could not

  17. Fluid immiscibility and gold deposition in the Birimian quartz veins of the Angovia deposit (Yaouré, Ivory Coast)

    NASA Astrophysics Data System (ADS)

    Coulibaly, Y.; Boiron, M. C.; Cathelineau, M.; Kouamelan, A. N.

    2008-02-01

    The Paleoproterozoic terranes (Birimian) of West Africa are well known to host numerous economic gold mineralizations. The Angovia gold mineralization is located in a brecciated and mylonitic zone within the Birimian greenstones. The sulfide-gold mineralization is mainly represented by gold associated with pyrite and chalcopyrite. A fluid inclusion study undertaken on mineralized quartz veins revealed the presence of aqueous-carbonic (CO 2-H 2O) fluids, the association of carbonic (CO 2) and early aqueous fluids, followed by later aqueous (H 2O-salt) and finally nitrogen-rich fluids. Entrapment of the initial homogeneous aqueous-carbonic fluids prior to fluid immiscibility depicts the evolution of the P-T conditions during the exhumation of the terranes after the peak of green-schist metamorphism. The CO 2 rich-fluid occurs especially in gold-bearing quartz, and are considered as the main evidence of the ore-forming process in the gold-bearing quartz veins. It is considered as a product of immiscibility of the CO 2-H 2O parent. The volatile fraction of carbonic and aqueous-carbonic fluid inclusions is dominated by CO 2, containing minor amounts of N 2, even smaller amounts of CH 4 and sporadically, H 2S. The aqueous-carbonic fluids have moderate salinity (3-10 wt.% eq. NaCl). Late aqueous and N 2 - (CH 4-CO 2) fluids are considered as later, unrelated to the main ore stage, and were trapped during the cooling of the hydrothermal system from 300 to 200 °C. The immiscibility has been favored by a strong pressure drop, the main trapping P-T conditions being 320-370 °C and 105-135 MPa. The mineralizing process is likely related to the immiscibility event, which was probably favored by the release of the fluid pressure after fracturing along the main shear zones. The ore process is likely to have occurred along the main shear zones or related secondary structures affected by cycling of the fluid pressure and quartz sealing-fracturing processes. The superimposed process can also explain the relative complexity of the quartz textures and fluid inclusion microfractures, and the rather wide range in the density of both parent fluid and CO 2-dominated fluid.

  18. 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.

  19. Permeability evolution in quartz fault gouges under hydrothermal conditions

    Microsoft Academic Search

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

    2007-01-01

    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

  20. Prospective Areas for Intrusion-Related Gold-Quartz Veins in Southern British Columbia

    Microsoft Academic Search

    James M. Logan

    trusion-related gold-quartz vein occurrences (i.e. Valparaiso and Cam-Gloria) are located in southern Brit- ish Columbia associated with the mid-Cretaceous Bayonne Suite (Logan, 2000). In contrast with the metaluminous, subalkalic, reduced I-type Tombstone Suite, t he B ayonne s uite c onsists o f m ostly peraluminous, s ubalkalic h ornblende-bioti te granodiorite and highly fractionated 2-mica granites, aplites and pegmatites.

  1. 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 intracrystalline microfractures. These fractures were rapidly sealed by nucleation of new grains as transiently over-pressured fluids flushed the deforming system. The new nucleated grains grew initially by solution-precipitation and later by grain boundary migration. They are relatively strain free and show a scattered CPO in resemblance with the host grain, although there is a slight synthetic rotation of the crystallographic axes. Due to the random initial orientation of the vein crystals, strain was thus accommodated differently in the individual crystals, leading to the development of remarkably different microstructures. Crystals oriented optimally for basal slip accommodated strain mainly in a viscous fashion and experienced only minor to no fracturing. Instead, crystals misoriented for basal slip hardened and deformed by pervasive fracturing promoted by the fluid over-pressure and controlled by the orientation of crystallographic planes. Viscous deformation continued after the microfractures sealed, again increasing the fluid pressure. This study indicates the importance of considering shear zones as dynamic systems wherein the activated deformation mechanisms vary transiently in response to the complex temporal and spatial evolution of the shear zone, often in a cyclic fashion.

  2. 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 ?47 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 initial water is 6.31 permil of SMOW which is totally different from the values of -5.36 and -6.5~-7.1 in the meteoric water of Chingshui area and the scaling of Well IC-13, respectively. This result infers that the compositions of hot fluids may be changed with different source in the Chingshui geothermal field.

  3. Detailed determination of palaeofluid chemistry: an integrated study of sulphate-volatile rich brines and aquo-carbonic fluids in quartz veins from Ouro Fino (Brazil)

    Microsoft Academic Search

    Marie-Christine Boiron; Alain Moissette; Michel Cathelineau; David Banks; Christophe Monnin; Jean Dubessy

    1999-01-01

    This paper presents the results of a detailed determination of the chemistry of an unusual palaeo-fluid, using an integrated approach based on multi-technique analyses of fluid inclusions. The investigated samples were retrograde metamorphic quartz veins from Ouro Fino (Quadrilatero Ferrifero, Minas Gerais, Brazil): (i) hematite-quartz veins which crosscut itabirites and display complex inclusion fluid chemistries, (ii) sulphide-quartz veins found in

  4. Source of lead in the gold-bearing quartz-fuchsite vein at the Dome mine, Timmins area, Ontario, Canada

    Microsoft Academic Search

    R. P. Moritz; J. H. Crocket; A. P. Dickin

    1990-01-01

    The quartz-fuchsite vein at the Dome mine, Timmins area, Canada, is characterized by a consistent spatial association of gold and galena. A lead isotope study was carried out to trace the source of the lead in the galenas, and to evaluate possible source reservoirs for the gold. Although other sources cannot be entirely ruled out, the lead isotope composition of

  5. Quartz precipitation and fluid inclusion characteristics in sub-seafloor hydrothermal systems associated with volcanogenic massive sulfide deposits

    NASA Astrophysics Data System (ADS)

    Steele-MacInnis, Matthew; Han, Liang; Lowell, Robert; Rimstidt, J.; Bodnar, Robert

    2012-06-01

    Results of a numerical modeling study of quartz dissolution and precipitation in a sub-seafloor hydrothermal system have been used to predict where in the system quartz could be deposited and potentially trap fluid inclusions. The spatial distribution of zones of quartz dissolution and precipitation is complex, owing to the fact that quartz solubility depends on many inter-related factors, including temperature, fluid salinity and fluid immiscibility, and is further complicated by the fact that quartz exhibits both prograde and retrograde solubility behavior, depending on the fluid temperature and salinity. Using the PVTX properties of H2O-NaCl, the petrographic and microthermometric properties of fluid inclusions trapped at various locations within the hydrothermal system have been predicted. Vapor-rich inclusions are trapped as a result of the retrograde temperature-dependence of quartz solubility as the convecting fluid is heated in the vicinity of the magmatic heat source. Coexisting liquid-rich and vapor-rich inclusions are also trapped in this region when quartz precipitates as a result of fluid immiscibility that lowers the overall bulk quartz solubility in the system. Fluid inclusions trapped in the shallow subsurface near the seafloor vents and in the underlying stockwork are liquid-rich with homogenization temperatures of 200-400°C and salinities close to that of seawater. Volcanogenic massive sulfide (VMS) deposits represent the uplifted and partially eroded remnants of fossil submarine hydrothermal systems, and the relationship between fluid-inclusion properties and location within the hydrothermal system described here can be used in exploration for VMS deposits to infer the direction towards potential massive sulfide ore.

  6. Measuring quartz solubility by in situ weight-loss determination using a hydrothermal diamond cell

    NASA Astrophysics Data System (ADS)

    Wang, Halan M.; Henderson, Grant S.; Brenan, James M.

    2004-12-01

    The solubility of quartz was determined using a hydrothermal diamond anvil cell (HDAC) within the temperature and pressure ranges of 126 to 490°C and up to 8.9 kbar, respectively. A novel approach has been used to measure the amount of dissolved silica. The quartz was abraded into spheres which have a diameter of ˜40 ?m. The spheres were then placed in pure water inside the diamond anvil cell and heated externally. Because the transparency of the diamonds allows direct observation of the sample chamber during the experiment, we were able to estimate the amount of quartz dissolved in the water at various stages of the dissolution process by measuring the decrease in the sphere's diameter over time. Experiments were performed along isochores between 0.92 and 0.99 g/cm 3. The maximum solubility measured was 0.165 molal. The experimental solubility data were limited to 370°C because of overestimation of solubilities above this temperature. Reprecipitation of silica inside the HDAC sample chamber and the refaceting of the spheres to trigonal form at temperatures above 350°C are major contributors to the overestimation.

  7. Deformation assisted by fluids in quartz veins of shear zones: an example from Iron Formations of Quadrilátero Ferrífero, Brazil.

    NASA Astrophysics Data System (ADS)

    Barbosa, Paola; Lagoeiro, Leonardo

    2013-04-01

    The evidences of fluid activity in rocks are well recognized. In many cases, the fluid is responsible to remobilize many elements (e.g. Au, Mn, Si) that may be transported over a long distance and precipitated as new minerals in regions of low stress of the rock. In many deformed rocks, the origin of a large number of structures (veins, pressure shadows, dissolved grain boundaries, etc) may be correlated to the fluid activity. However, the fluids are important not only during the crack-and-seal process but also after the sealing ceases. As an example of how the fluids are responsible to rearrange the structure of the rock, we studied many quartz veins of one iron-formation from Brazil. The rocks were collected in Quadrilátero Ferrífero (QF), Brazil, that is one of the most important metalogenetic provinces in the world. It is assumed the existence of a deformational and metamorphic gradient in the rocks of QF, increasing the occurrence of penetrative structures from southwest to northeast. However, the effects of the local shear zones in the deformation pattern of QF may not be neglected. Shear zones are generally recognized as structures that accommodate deformation, eventually with intense fluid percolation. It is indubitable that there is a relationship between the fluid activity and the deformation accommodation in shear zones. So, to investigate how the fluid activity can affect the mechanisms of accommodation of deformation in rocks of shear zones from QF, we characterized the crystallographic preferred orientation (CPO) of some quartz vein by EBSD (electron backscattering diffraction). All the samples came from the same outcrop and from the same dextral shear zone, localized in the low-deformation region of QF, under greenschist metamorphic conditions. The samples were oriented according to the XYZ reference system, with X parallel to the foliation and Z normal to the XY plane. The veins are quartz-rich layers parallel to the rock foliation. They do not exhibit any kind of fibrous structures that can indicate a sense of growth of the quartz crystals inside the vein. The less deformed veins are composed of tabular crystals of quartz, with the optical axes oriented sub-parallel to the foliation. Mechanical Dauphiné twinning of quartz may also be observed in the single crystals. On the other hand, the deformed veins are represented by polycrystalline layers of quartz, with two distinct CPOs of c-axes: 1) oblique to the foliation and 2) parallel to the Y axis. We suppose that the veins are the result of a concurrence between transformation, recrystallization and recovery of quartz assisted by fluid activity at low temperature and confining pressure. In the related deformation conditions, slip on basal planes and mechanical twinning are consistent with a strong c-axis CPO of quartz sub-parallel to the foliation, but it is not acceptable to the c-axis CPO around Y. To achieve this distinct crystallographic orientation, it is necessary a slip system on prismatic planes followed by grain boundary migration. At low temperatures, one possible situation to explain the CPO under theses conditions is the progressive deformation assisted by fluid activity. A posterior static recrystallization by discontinuous grain growth of quartz may be responsible for the concentration of the c-axis around the Y, intensifying the CPO.

  8. 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 inclusions). Two types of samples were taken from the auriferous quartz vein; samples from the outer zone (Rim) and samples from the inner zone (Core). With respect to number of phases present at the room temperature (20 °C) there are two main groups of fluid inclusions can be recognized in both zones: A) two-phase - aqueous inclusions (Type I) and B) three-phase - carbonic-rich inclusions (Type II). Type I inclusions could be further subdivided into two sub-types (H2O-NaCl±KCl) and (H2O-NaCl±MgCl2) systems, based mainly on the eutectic temperature (Teu). For (H2O-NaCl±KCl) system, eutectic temperatures range from -22.1 °C to -23.9 °C at the rim and from -22.7 °C to -23.5 °C at the core. Values of homogenization temperatures (Th) are between (190.4 °C - 273.1 °C) at the rim and between (217 °C - 281.1 °C) at the core. Salinity has a range of (0.73 to 4.7 mass% of NaCl) at the rim and (0 to 1.65 mass% of NaCl) at the core. For (H2O-NaCl± MgCl2) system, eutectic temperatures range from -32.7 °C to -35 °C at the rim and from -33.9 °C to -34.2 °C at the core. Values of homogenization temperatures are up to 376.1 °C at the rim and between (310.6 °C - 480.2 °C) at the core. Salinity has a range of (2.15 to 3.8 mass% of NaCl) at the rim and (2.15 to 3.65 mass% of NaCl) at the core. Type II inclusions of (H2O-NaCl-CO2±CH4) system, most of them were homogenized to liquid state and the other were homogenized to vapour or rarely to critical state. The total homogenization temperature ranges between (260 °C - 340 °C) at the rim with low salinity (0 - 4.2 mass% NaCl equiv.) and density of range (0.49 - 0.86 g/cc). Within core samples, the total homogenization temperature ranges between (299.9 °C - 408.8 °C) with salinity (3.73 - 4.78 mass% of NaCl equiv.) and density of range (0.61 - 0.87 g/cc). These data are consistent with transportation of gold as a bisulphide complex, likely due to decreases in sulphur activity accompanying fluid unmixing.

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

    NASA Astrophysics Data System (ADS)

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

    1986-06-01

    Archaean gold-quartz vein/shear zone systems constitute one of the most important types of gold ore deposit; however, their origin is controversial. Here we discuss newly obtained ?13C(PDB) values for carbonate associated with the second largest such system in the world (Hollinger-McIntyre, Superior Province, Canada), together with values for fourteen other Au-mineralized locations in the Timmins area1 and for the largest such system in the world (Golden Mile, Western Australia2). All of the data are statistically identical to the ?13C values, reported here, of proven magmatic carbonate recently found with Au- and W-enriched MoS2 mineralization in the Mink Lake sodic granodiorite stock, northwest Ontario. The ?13C values appear to exclude greenschist-amphibolite facies metamorphic processes, a widely accepted genetic alternative3-6, and granulite facies processes7,8. We conclude that currently available carbon isotope data suggest that the H2O-CO2 fluid which deposited this type of Archaean Au mineralization was magmatically derived.

  10. 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 vein epidotes may result from only minor changes in the fugacity of CO2, O2, and S2 of the geothermal fluid.

  11. U-Pb-Th geochronology of monazite and zircon in albitite metasomatites of the Rož?ava-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.; Kone?ný, P.; Dianiška, I.

    2015-05-01

    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.

  12. Fluid Inclusion Evidence for Magmatic-Hydrothermal Fluid Evolution in the Porphyry Copper-Molybdenum Deposit at Butte, Montana

    Microsoft Academic Search

    BRIAN G. RUSK; MARK H. REED; JOHN H. DILLES

    2008-01-01

    The porphyry Cu-Mo deposit in Butte, Montana, formed where magmatic hydrothermal fluids, introduced with injections of porphyrytic dikes, fractured and permeated the Butte Quartz Monzonite. These fluids formed a stockwork of quartz and quartz-sulfide veinlets with a variety of styles of potassic and sericitic alter- ation envelopes. The distribution of vein and alteration types and the distribution of fluid inclusions

  13. 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.

  14. 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.

  15. 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 kilometres above the base of the greenstone belt. Mass balance calculations involving bulk ore indicate enrichment of both felsic (K, Rb, Cs, Li, Ba, W) and mafic elements (Ca, Sr, Mg, Ni, V, Cr, Te), a source signature compatible with the local high-Mg porphyry suite but not with the meta-gabbro host rock. The initial 87Sr/86Sr ratios of the vein scheelites (0.7014-0.7016) are higher than the mantle ratio of the meta-gabbro (0.7009-0.7011) and overlap those of high-Mg monzodiorite intrusions (0.7016-0.7018) emplaced along the Golden Mile Fault at 2,662 ± 6 Ma to 2,658 ± 3 Ma.

  16. Annular fluid inclusions from a quartz vein intercalated with metapelites from the Besshi area of the Sanbagawa belt, SW Japan

    NASA Astrophysics Data System (ADS)

    Yoshida, Kenta; Hirajima, Takao

    Annular fluid inclusions were found in a foliation-parallel quartz vein intercalated with metapelites from the Besshi area of the Sanbagawa belt, SW Japan. The preserved “foam microstructure” of the quartz vein suggests low differential stress at high temperatures for its formation. Three types of fluid inclusions have been identified: the earliest one, FIA-I, is characterized by two phase inclusions arranged along intragranular planes and mainly composed of aqueous saline fluid and CH4 gas; FIA-II texturally comparable to FIA-I consists of CH4-N2-CO2-H2 gas phase inclusions with rare two-phase inclusions; the latest type, FIA-III, is characterized by arrangements along transgranular planes consisting of two-phase inclusions mainly composed of CH4-N2 vapor in aqueous saline fluid. Amongst them, FIA-I contains annular fluid inclusions, which are attributed to reequilibration due to a confining pressure increase, suggesting that the host rock underwent the compression after the entrapment of FIA-I. Textural observations and chemical characteristics show that FIA-I and -II were trapped during prograde or near the peak metamorphic stage, and that FIA-III was probably trapped at an early stage of the exhumation.

  17. Halogen and Ar–Ar age determinations of inclusions within quartz veins from porphyry copper deposits using complementary noble gas extraction techniques

    Microsoft Academic Search

    M. A Kendrick; R Burgess; R. A. D Pattrick; G Turner

    2001-01-01

    Extension of Ar–Ar methodology has been used to determine mineralisation ages from mica inclusions and to simultaneously evaluate the noble gas and halogen composition of inclusion fluids within irradiated quartz vein samples from five porphyry copper deposits. Samples have been collected from the potassic and propylitic zones of Bingham Canyon, Utah, and four Arizonan deposits; Silverbell, Globe-Miami, Pinto Valley and

  18. Ion microprobe analysis of oxygen isotope ratios in quartz from Skye granite: healed micro-cracks, fluid flow, and hydrothermal exchange

    Microsoft Academic Search

    John W. Valley; Colin M. Graham

    1996-01-01

    Quartz grains in hydrothermally altered granites from the Isle of Skye are highly heterogeneous and not equilibrated in oxygen\\u000a isotope ratio at the 20??m scale. Ion microprobe analysis of one grain shows a gradient of 13‰ over 400??m and a greater range\\u000a in ?\\u000a 18O than all quartz previously analyzed on the Isle of Skye. Other crystals from the same

  19. 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.

  20. Hydrothermal Alteration and Mineralization Zoning in Iron-Oxide(-Cu-Au) Vein Deposits, near Copiap, Chile

    E-print Network

    Barton, Mark D.

    as a function of structural levels. Two vein systems hosted in La Brea diorite phase of the Copiapó batholith vein formed near the upper contact of the host La Brea diorite. Few IOCG systems have well documented and Sollner, 2006; M.D. Barton et al., unpubl. data). The plutons are broadly dioritic in composition

  1. 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 pressures. Thus, periods of tectonic stress inversion, characterised by sustained near-lithostatic fluid pressures and low shear stresses, turn out to be key moments of enhanced permeability in mid-crustal, low-permeability environments, guaranteeing fluid-pressure driven flow of internally-derived metamorphic fluids. Syn-orogenic veining, on the other hand, is relatively uncommon in the slate belt. Quartz veins occupy deformation-controlled, low-displacement, structures (e.g. saddle reefs, dilational jogs, boudin necks). During the main stages of orogeny, rather locally enhanced permeability is thus primarily deformation-controlled. Throughout orogeny, intermittent, crustal-scale enhanced permeability is materialized by the different quartz-vein occurrences. Quartz veins occupy low-displacement structures, reflecting brittle (e.g. fault-fracture meshes) or ductile deformation (e.g. folds). Remarkably, the enhanced permeability is highly anisotropic, with primarily a horizontal connectivity, parallel to the intermediate principal stress or the structural grain. Mixed brittle-plastic deformation behaviour is furthermore responsible for maintaining long-lived permeability structures by a steady-state deformation of fluid-filled cavities, ensuring sustained, crustal-scale fluid flow.

  2. Slip velocity has major impact on the frictional strength and microstructure of quartz-muscovite gouges under hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Niemeijer, Andre R.

    2015-04-01

    Previous friction experiments on rock analogue experiments of mixtures of salt and phyllosilicates, demonstrated the possibility of producing mylonitic fault rocks through the simultaneous operation of pressure solution and frictional sliding. This frictional-viscous flow process produces a strong velocity-dependence of friction, with friction values dropping from 0.8 to ~0.2-0.3 over just one order of magnitude decrease in sliding velocity. Here, we present the results of rotary shear experiments on simulated fault gouges of 80 wt% quartz and 20 wt% muscovite. Sliding experiments using a four orders of magnitude range of constant velocities (0.03 - 300 ?m/s) to a displacement of 30 mm were done at 500 ° C, 120 MPa effective normal stress and 80 MPa fluid pressure to verify the mechanism at hydrothermal conditions and to link the produced microstructure to the observed strength. At the lowest sliding velocity tested, final friction reached a value of ~0.3, which is lower than that of pure muscovite under similar conditions. With increasing sliding velocity, friction increases, reaching a maximum of ~0.9 at 3 ?m/s after which it decreases mildly to ~0.8 at 300 ?m/s. The bulk microstructure of the sample sheared at 0.03 ?m/s shows an anastomosing foliation of muscovite grain intervened by asymmetrical quartz clasts, with an average grain size of about 20 ?m, slightly lower than the median starting size (~49 ?m). In contrast, the grains of the sample deformed at 300 micron/s are very small, many of them smaller than distinguishable in the light microscope (i.e. < 1 ?m). In addition, the microstructure is characterized by clear bands of strong uniform extinction in P- and B-shear orientations, possibly indicating a Crystallographic Preferred Orientation. These zones of uniform extinction can be found in all samples and their thickness decreases monotonically with decreasing sliding velocity. The microstructure observed at low velocity, in the frictional-viscous regime, is similar to numerous examples from natural fault rocks (e.g. the Median Tectonic Line and the Zuccale Fault). The slowest sliding velocity employed here corresponds to a shear strain rate of ~3 * 10-5 s-1, still several orders of magnitude higher than tectonic plate rates (~10-10to 10-8 for fault thicknesses of 1 to 0.01 m). At natural, lower strain rates, the frictional-viscous flow regime, where friction is low, is predicted to be operative down to temperatures as low as 250 ° C and possibly even lower for other minerals than quartz. In contrast to the low velocity regime, microstructures similar to those observed here at high velocity, have not been reported for natural fault rocks, implying that either these do not survive exhumation (possibly due to the very fine grain size), get overprinted by later, slow deformation, or are not formed in the first place. The strain rates here are still well below the values reached during seismic slip and are probably not common values in nature, nor will they be long-lived and thus not impose a large shear strain. Dynamic or static grain growth after a transient, faster slip pulse will most likely obliterate any evidence of slip rates fluctuating between aseismic and seismic. Clearly, more hydrothermal experiments aimed at understanding the link between the fault microstructure and its strength and the variation of these with sliding velocity, are needed.

  3. From evaporated seawater to uranium-mineralizing brines: Isotopic and trace element study of quartz-dolomite veins in the Athabasca system

    NASA Astrophysics Data System (ADS)

    Richard, Antonin; Boulvais, Philippe; Mercadier, Julien; Boiron, Marie-Christine; Cathelineau, Michel; Cuney, Michel; France-Lanord, Christian

    2013-07-01

    Stable isotope (O, H, C), radiogenic isotope (Sr, Nd) and trace element analyses have been applied to quartz-dolomite veins and their uranium(U)-bearing fluid inclusions associated with Proterozoic unconformity-related UO2 (uraninite) ores in the Athabasca Basin (Canada) in order to trace the evolution of pristine evaporated seawater towards U-mineralizing brines during their migration through sediments and basement rocks. Fluid inclusion data show that quartz and dolomite have precipitated from brines of comparable chemistry (excepted for relatively small amounts of CO2 found in dolomite-hosted fluid inclusions). However, ?18O values of quartz veins (?18O = 11‰ to 18‰) and dolomite veins (?18O = 13‰ to 24‰) clearly indicate isotopic disequilibrium between quartz and dolomite. Hence, it is inferred that this isotopic disequilibrium primarily reflects a decrease in temperature between the quartz stage (˜180 °C) and the dolomite stage (˜120 °C). The ?13C values of CO2 dissolved in dolomite-hosted fluid inclusions (?13C = -30‰ to -4‰) and the ?13C values of dolomite (?13C = -23.5‰ to -3.5‰) indicate that the CO2 dissolved in the mineralizing brines originated from brine-graphite interactions in the basement. The resulting slight increase in the fluid partial pressure of CO2 (pCO2) may have triggered dolomite precipitation instead of quartz. ?18O values of quartz veins and previously published ?18O values of the main alteration minerals around the U-ores (illite, chlorite and tourmaline) show that quartz and alteration minerals were isotopically equilibrated with the same fluid at ˜180 °C. The REE concentrations in dolomite produce PAAS-normalized patterns that show some similarities with that of UO2 and are clearly distinct from that of the other main REE-bearing minerals in these environments (monazite, zircon and aluminum phosphate-sulfate (APS) minerals). The radiogenic isotope compositions of dolomite (87Sr/86Sri = 0.7053 to 0.7161 and ?Nd(t) = -8.8 to -20.3) differ from one deposit to another, reflecting both heterogeneity in the basement geology and variable preservation of the original composition of brines. The previously published 87Sr/86Sri and ?Nd(t) values of UO2 compare with the most evolved dolomites, i.e. dolomites precipitated from brines that exchanged the most with the basement. This reinforces a close genetic link between dolomites and UO2 deposition and implies that UO2 deposition occurred in a cooling system during the transition from quartz to dolomite formation. The ?18O and ?D values of the mineralizing brines (?18O = -1‰ to 8‰ and ?D = -150‰ to -50‰) are considerably shifted from that of their theoretical original values acquired during evaporation of seawater (?18O = ˜-3‰ and ?D = ˜-40‰). The positive ?18O shift is explained by protracted fluid-rock interaction within the basin and basement rocks. The negative ?D shift is attributed to incomplete mixing between the U-mineralizing brines and low ?D water. This low ?D water was likely produced during the abiogenic synthesis of bitumen by Fisher-Tropsch-like reactions involving CO2 derived from brine-graphite interaction in the basement, and radiolytic H2. The resulting low ?D brines have been equilibrated with alteration minerals. This may explain why some alteration minerals yield anomalously low ?D values whose significance has long been debated.

  4. 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. [Australian Nuclear Science and Technology Organisation, PMB 1, Menai, 2234 (Australia); Giere, Reto [Mineralogisch-Geochemisches Institut, Albert-Ludwigs-Universitaet, Freiburg, D-79104 (Germany)

    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)

  5. Microbeam Analyses of Rare-Earth Element (REE) and Sr Isotopes of Anhydrite Veins From the PACMANUS Hydrothermal System

    NASA Astrophysics Data System (ADS)

    Craddock, P. R.; Bach, W.

    2004-12-01

    Ocean Drilling Program Leg 193 drilled into areas of focused and diffuse venting from the PACMANUS hydrothermal field along Pual Ridge, eastern Manus Basin. Pual Ridge is primarily composed of fresh dacite that is pervasively altered to argillaceous (illite-chlorite) and overprinting acid-sulfate (pyrophyllite-anhydrite) and siliceous secondary mineral assemblages. Anhydrite is an abundant precipitate in all cores recovered beneath the active vent field. Isotopic (Sr, S), elemental (Mg, Sr, REE) and fluid inclusion analyses on anhydrite mineral separates demonstrate that pathways of fluid evolution (magmatic input, variable fluid composition, seawater entrainment) differ on the meter scale within this system. In addition, large variations in REE content, S (? 34S > 5‰ ) and Sr (87Sr/86Sr > 1000 ppm) isotope composition are observed within individual anhydrite veins. Using microbeam techniques, we have analyzed this small scale chemical and isotopic heterogeneity in order to unravel the record of hydrothermal processes occurring at PACMANUS. Cathodoluminescence microscopy is used to distinguish between different crystal growth textures (e.g., oscillatory versus sector zoning). A Finnigan Neptune laser-ablation MC-ICP-MS is used to measure 87Sr/86Sr, and a Cameca 3f ion microprobe and a Finnigan Element2 laser-ablation MC-ICP-MS to measure REE and minor element concentrations in these zones. Initial microbeam measurements of sector-zoned crystals reveal REE patterns trending from mid-REE enriched to MREE depleted with distance from crystal center and with a uniform 87Sr/86Sr (0.7087). Analyses for oscillatory zoned crystals reveal variable and increasing 87Sr/86Sr (0.7043 to 0.7089) and REE patterns trending from light-REE enriched to LREE depleted with both negative and positive Eu anomalies during crystal growth. 87Sr/86Sr reproducibility for an isotopically homogenous anhydrite is better than 40 ppm. The Sr isotopic composition range for heterogenous crystals (> 4000 ppm) is hence greater than 100 times the analytical uncertainty of our LA-MC-ICP-MS method. The general trend of these data can be modeled by Rayleigh-type fractional crystallization of anhydrite, with sector zoned anhydrite precipitating from a seawater dominated fluid and oscillatory zoned anhydrite forming from a hydrothermally dominated fluid following introduction of seawater into the basement. Future microbeam REE, Sr and S-isotope analyses are planned to provide a more comprehensive view of fluid evolution and mineral formation within this backarc hydrothermal system.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    Room-temperature friction and indentation experiments suggest fault strengthening during the interseismic period results from increases in asperity contact area due to solid-state deformation. However, field observations on exhumed fault zones indicate that solution-transport processes, pressure solution, crack healing and contact overgrowth, influence fault zone rheology near the base of the seismogenic zone. Contact overgrowths result from gradients in surface curvature, where material is dissolved from the pore walls, diffuses through the fluid and precipitates at the contact between two asperities, cementing the asperities together without convergence normal to the contact. To determine the mechanisms and kinetics of asperity cementation, we conducted laboratory experiments in which convex and flat lenses prepared from quartz single crystals were pressed together in an externally heated pressure vessel equipped with an optical observation port. Convergence between the two lenses and contact morphology were continuously monitored during these experiments using reflected-light interferometry through a long-working-distance microscope. Contact normal force is constant with an initial effective normal stress of 1.7 MPa. Four single-phase experiments were conducted at temperatures between 350 and 530C at 150 MPa water pressure, along with two controls: one single phase, dry at 425C and one bimaterial (qtz/sapphire) at 425C and 150 MPa water pressure. No contact growth or convergence was observed in either of the controls. For wet single-phase contacts, however, growth was initially rapid and then decreased with time following an inverse squared dependence of contact radius on aperture. No convergence was observed over the duration of these experiments, suggesting that neither significant pressure solution nor crystal plasticity occurred at these stresses and temperatures. The formation of fluid inclusions between the lenses 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, a definitive indication of diffusion-limited growth. Diffusion-limited growth is also consistent with the inverse squared aperture dependence. However, the apparent activation energy is ~125 kJ/mol, much higher than expected for silica diffusion in bulk water; at present we do not have a complete explanation for the high activation energy. When our lab-measured overgrowth rates are extrapolated to the 5 to 30 micron radius contacts inferred from near-field recordings of M-2 sized earthquakes in deep drill holes and mines (i.e., SAFOD and NELSAM), we predict rates of contact area increase that are orders of magnitude faster than seen in dry, room-temperature friction experiments. This suggests that natural strength recovery should be dominated by fluid-assisted processes at hypocentral conditions near the base of the seismogenic zone.

  7. 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., E-mail: kikuma.jb@om.asahi-kasei.co.jp [Analysis and Simulation Center, Asahi-KASEI Corporation, 2-1 Samejima Fuji, Shizuoka 416-8501 (Japan); Tsunashima, M.; Ishikawa, T.; Matsuno, S. [Analysis and Simulation Center, Asahi-KASEI Corporation, 2-1 Samejima Fuji, Shizuoka 416-8501 (Japan); Ogawa, A.; Matsui, K. [Construction Materials Laboratory, Asahi-KASEI Construction Materials Corporation, Sakai-machi, Ibaraki 306-0493 (Japan); Sato, M. [Industrial Application Division, SPring-8/JASRI, Sayo, Hyogo 679-5198 (Japan)

    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.

  8. Mineralogy and geochemistry of a Late Permian coal in the Dafang Coalfield, Guizhou, China: Influence from siliceous and iron-rich calcic hydrothermal fluids

    USGS Publications Warehouse

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

    2005-01-01

    This paper describes the influence of siliceous and iron-rich calcic low-temperature hydrothermal fluids (LTHF) on the mineralogy and geochemistry of the Late Permian No. 11 Coal (anthracitic, Rr =2.85%) in the Dafang Coalfield in northwestern Guizhou Province, China. The No. 11 Coal has high contents of vein ankerite (10.2 vol.%) and vein quartz (11.4 vol.%), with formation temperatures of 85 and 180 ??C, respectively, indicating that vein ankerite and vein quartz were derived from low-temperature calcic and siliceous hydrothermal fluids in two epigenetic episodes. The vein quartz appears to have formed earlier than vein ankerite did, and at least three distinct stages of ankerite formation with different Ca/Sr and Fe/Mn ratios were observed. The two types of mineral veins are sources of different suites of major and trace metals. Scanning electron microscope and sequential extraction studies show that, in addition to Fe, Mg, and Ca, vein ankerite is the dominant source of Mn, Cu, Ni, Pb, and Zn in the coal, and the contents of these five elements are as high as 0.09% and 74.0, 33.6, 185, and 289 ??g/g, respectively. In contrast, vein quartz is the main carrier mineral for platinum-group elements (PGEs) Pd, Pt, and Ir in the coal, and the contents of Pd, Pt, and Ir are 1.57, 0.15, and 0.007 ??g/g, respectively. Sequential extraction showed a high PGE content in the silicate fraction, up to 10.4 ??g/g Pd, 1.23 ??g/g Pt, and 0.05 ??g/g Ir, respectively. It is concluded that the formation of ankerite and quartz and the anomalous enrichment of trace elements in the No. 11 Coal in the Dafang Coalfield, Guizhou, result from the influx of calcic and siliceous low-temperature hydrothermal fluids. ?? 2004 Elsevier B.V. All rights reserved.

  9. Native gold and ore mineral inclusions in detrital zircon and quartz from the early precambrian quartzites and quartz gravelstones of the Karelian Craton

    NASA Astrophysics Data System (ADS)

    Kozhevnikov, V. N.; Safronov, A. N.

    2012-05-01

    The study of solid mineral inclusions in detrital hydrothermal and hydrothermally altered zircons and quartz from Archaean and Palaeoproterozoic (Sumian and Jatulian) terrigenous quartz-rich clastic rocks of the Karelian Craton on a VEGA II LSH-TESKAN microanalyzer has revealed, for the first time, micron-sized native gold inclusions and associated syngenetic inclusions of ore minerals, such as galena, sphalerite, pyrite, chalcopyrite, molybdenite, molybdoscheelite, native bismuth and cerussite, as well as barite and complex hydroaluminophosphates of the goyacite-gorceixite-florencite-plumbogummite group. This mineral association in detrital material could indicate the ore-forming nature of its quartz vein source. These data, together with the earlier results of the local isotopic (SHRIMP-II and LA-ICP-MS) dating of these and similar heterogeneous detrital zircons, are indicative of several hydrothermal events, dated at 3.3, 3.15-2.9 and 2.76-2.65 Ga, which occurred in the region in Archaean time. The two latter ages are consistent with the time of formation of quartz vein ore systems with some of which gold ore-forming processes were associated.

  10. Origin of the CO 2-only fluid inclusions in the Palaeoproterozoic Carará vein-quartz gold deposit, Ipitinga Auriferous District, SE-Guiana Shield, Brazil: Implications for orogenic gold mineralisation

    Microsoft Academic Search

    Evandro L. Klein; Kazuo Fuzikawa

    2010-01-01

    The Carará gold deposit, located in the Ipitinga Auriferous District, south-eastern portion of the Guiana Shield, northern Brazil, is a typical orogenic, greenstone-hosted, auriferous quartz vein. Mineralisation was post-metamorphic and syn-tectonic in relation to the host Palaeoproterozoic (ca. 2.03Ga) shear zone developed close to the tectonic boundary between a Palaeoproterozoic continental arc and an Archaean block. The deposit style is

  11. 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.

  12. 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.

  13. A case study of impact-induced hydrothermal activity: The Haughton impact structure, Devon Island, Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Osinski, Gordon R.; Lee, Pascal; Parnell, John; Spray, John G.; Baron, Martin

    2005-12-01

    The well-preserved state and excellent exposure at the 39 Ma Haughton impact structure, 23 km in diameter, allows a clearer picture to be made of the nature and distribution of hydrothermal deposits within mid-size complex impact craters. A moderate- to low-temperature hydrothermal system was generated at Haughton by the interaction of groundwaters with the hot impact melt breccias that filled the interior of the crater. Four distinct settings and styles of hydrothermal mineralization are recognized at Haughton: a) vugs and veins within the impact melt breccias, with an increase in intensity of alteration towards the base; b) cementation of brecciated lithologies in the interior of the central uplift; c) intense veining around the heavily faulted and fractured outer margin of the central uplift; and d) hydrothermal pipe structures or gossans and mineralization along fault surfaces around the faulted crater rim. Each setting is associated with a different suite of hydrothermal minerals that were deposited at different stages in the development of the hydrothermal system. Minor, early quartz precipitation in the impact melt breccias was followed by the deposition of calcite and marcasite within cavities and fractures, plus minor celestite, barite, and fluorite. This occurred at temperatures of at least 200 °C and down to ˜100-120 °C. Hydrothermal circulation through the faulted crater rim with the deposition of calcite, quartz, marcasite, and pyrite, occurred at similar temperatures. Quartz mineralization within breccias of the interior of the central uplift occurred in two distinct episodes (˜250 down to ˜90 °C, and <60 °C). With continued cooling (<90 °C), calcite and quartz were precipitated in vugs and veins within the impact melt breccias. Calcite veining around the outer margin of the central uplift occurred at temperatures of ˜150 °C down to <60 °C. Mobilization of hydrocarbons from the country rocks occurred during formation of the higher temperature calcite veins (>80 °C). Appreciation of the structural features of impact craters has proven to be key to understanding the distribution of hydrothermal deposits at Haughton.

  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. Magnesiochloritoid-talc-garnet assemblages from the Tauern Window, Eastern Alps, Austria: high pressure metamorphosed oceanic hydrothermal veins

    NASA Astrophysics Data System (ADS)

    Miller, C.; Konzett, J.

    2003-04-01

    Magnesiochloritoid is a comparatively rare phase typically formed at pressures >2.0 GPa in Mg-rich meta-igneous and meta-sedimentary bulk compositions. While this phase has been described from a number of localities in the Western Alps including the Zermatt-Saas and Monviso ophiolites and the Monte Rosa Massif, only one locality from the Eastern Alps has been known so far which is located in the eclogite zone of the Tauern Window. Here, magnesiochloritoid was found in a fine-grained massive eclogite as large postkinematic poikiloblasts up to 5 mm in size that overgrow a mylonitic assemblage of garnet + omphacite + kyanite + talc + chlorite + rutile + paragonite + calcic amphibole, the latter two phases being products of retrogressive breakdown of kyanite + omphacite. In addition, magnesiochloritoid is present as decimeter-size segregations coexisting with talc + kyanite ± chlorite ± rutile ± paragonite. Magnesiochlorioid has an XMg of 0.63 which is well within the XMg range of 0.61--0.85 reported from the Western Alps. Omphacite appears in two generations: (1) large corroded and strongly zoned grains with rel. Al-poor and Fe-rich cores (jd37, XMg = 0.83) and Al-rich and Fe-poor rims (jd42-46, XMg = 0.91--0.94) and (2) small idomorphic grains (jd46-48, XMg = 0.96--0.98) similar in composition to rims of large corroded grains. Garnet, too, is strongly zoned with Mg-poor cores (alm62py15gross17) and discontinuous Mg-rich rims (alm42py39gross16). This zoning is attributed to recrystallization as a result of deformation under increasing pressure. Peak metamorphic conditions of 2.04 ± 0.16 GPa at temperatures of 623 ± 17^oC were derived from the equilibrium chlorite + kyanite = magnesiochloritoid + talc and the Fe-Mg exchange between garnet and clinopyroxene which is in good agreement with PT-data from mafic eclogites of the Tauern Window. The Mg-rich and Ca-poor bulk composition (11.6 wt% MgO, 7.8 wt% CaO) responsible for the presence of magnesiochloritoid and its occurrence in segregations associated with talc can be explained by Mg-metasomatism with attendant Ca-depletion as a result of ocean-floor hydrothermal activity that led to an enrichment of chlorite and/or smectite (cf. Widmer 1996). Trace element and isotopic whole rock data indicate an E-type MORB affinity. The absence of negative Nb-Ta-Ti anomalies precludes a subduction-modified and/or any significant crustal source component. Lit.: Widmer, T. et al., (2000) Schweiz. Mineral. Petrogr. Mitt. 80, 63--73

  16. Fluid inclusion evidence for hydrothermal fluid evolution in the Darreh-Zar porphyry copper deposit, Iran

    NASA Astrophysics Data System (ADS)

    Nateghi, Arash; Hezarkhani, Ardeshir

    2013-09-01

    The Darreh-Zar porphyry copper deposit is associated with a quartz monzonitic-granodioritic-porphyritic stock hosted by an Eocene volcanic sedimentary complex in which magmatic hydrothermal fluids were introduced and formed veins and alteration. Within the deepest quartz-rich and chalcopyrite-poor group A veins, LVHS2 inclusions trapped high salinity, high temperature aqueous fluids exsolved directly from a relatively shallow magma (0.5 kbar). These late fluids were enriched in NaCl and reached halite saturation as a result of the low pressure of magma crystallization and fluid exsolution. These fluids extracted Cu from the crystallizing melt and transported it to the hydrothermal system. As a result of ascent, the temperature and pressure of these fluids decreased from 600 to 415 °C, and approximately 500-315 bars. At these conditions, K-feldspar and biotite were stabilized. Type A veins were formed at a depth of ?1.2 km under conditions of lithostatic pressure and abrupt cooling. Upon cooling and decompressing, the fluid intersected with the liquid-vapor field resulting in separation of immiscible liquid and vapor. This stage was recorded by formation of LVHS1, LVHS3 and VL inclusions. These immiscible fluids formed chalcopyrite-pyrite-quartz veins with sericitic alteration envelopes (B veins) under the lithostatic-hydrostatic pressure regime at temperatures between 415 and 355 °C at 1.3 km below the paleowater table. As the fluids ascended, copper contents decreased and these fluids were diluted by mixing with the low salinity-external fluid. Therefore, pyrite-dominated quartz veins were formed in purely hydrostatic conditions in which pressure decreased from 125 bars to 54 bars and temperature decreased from 355 to 298 °C. During the magmatic-hydrothermal evolution, the composition and P-T regime changed drastically and caused various types of veins and alterations. The abundance of chalcopyrite precipitation in group B veins suggests that boiling and cooling were important factors in copper mineralization in Darreh-Zar.

  17. The solubility of natural quartz sand at 100?C, and 150?C, 345 bars: an experimental investigation in a flow-through hydrothermal system

    E-print Network

    Burns, Gregory Lee

    1989-01-01

    not quartz seems to conuol the silica concentration in geothermal systems below 180'C (Fournier, 1973 and 1977; Arnorsson, 1979). The eventual removal of these phases resulted from dissolution enhanced by the introduction of distilled water during the pore...-511. Arnorsson S. (1979) Hydrochemistry in geothermal investigations in Iceland: Techniques and applications. Nordic Hydrology 10, 191-224. Beckwith R. S. and Reeve R. (1969) Dissolution and deposition of mono-silicic acid in suspensions of ground quartz...

  18. The solubility of natural quartz sand at 100?C, and 150?C, 345 bars: an experimental investigation in a flow-through hydrothermal system 

    E-print Network

    Burns, Gregory Lee

    1989-01-01

    , calculated solubilities range I'rom 49 and 61 ppm At 150'C and 345 bars, the solubility was 161+ 8 ppm, significantly greater than calculated solubilities (130 to 144 ppm). The initial treatment of the starting solid did not affect the final solubility but... these conditions, the solubility of quartz has only been determined at temperatures and pressures along the liquid-vapor curve of water. Experiments have been conducted at 1013 bars (Morey er al. , 1962) and 1043 bars (Fournier, 1960) below 200'C, but the quartz...

  19. 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.

  20. 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) and quartz. In contrast, in Frasin maar-diatreme structure, the mineralizations are focused especially along the northeastern contact between the andesite dome and polimictic breccias. Stockwork is the main style of mineralization and consists of pyrite, small amounts of chalcopyrite, sphalerite, galena, arsenopyrite and gold within a gangue of quartz and carbonates similar to Rodu mineralizations. The ore minerals deposition from hydrothermal fluids have pulsated character with a three stage evolution and mineral assemblages: 1) magnetite (hematite) - pyrite (marcasite) - quartz in the first stage, epithermal low sulfidation with passing to mesothermal; 2) arsenopyrite (Au) - (-base metal sulfides) - quartz, "Chinga" (pyrite (Au)-quartz-adularia) - carbonates (calcite, aragonite, dolomite, ankerite, ± rhodochrosite ± kutnahorite) - quartz - adularia in the second stage, epithermal low sulfidation and 3) pyrite - marcasite - carbonates - quartz, (Au) - carbonates (dominant rhodochrosite) - quartz - adularia and alabandite - rhodochrosite - quartz in the third stage, epithermal low sulfidation. The mineralizing hydrothermal fluids had near neutral pH with the gold transported probably as a bisulfide complex; boiling seems to be the main way of gold precipitation.

  1. 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 those now prevailing.

  2. 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 studies and stage II mineral equilibria, gold deposited from a homogeneous, neutral to slightly alkaline (pH 5.1-5.5), reduced, low-salinity (<5.5 wt % NaCl equiv) fluid that had a bulk composition of 78 mole percent H2O and 21 mole percent CO2, and trace amounts of CH4, C2H6, H2, Ar, H2S, and He. Gold deposition occurred at 300?? ?? 50??C and 0.5 to 3.0 kbars. Assuming lithostatic fluid pressures, gold precipitated at a 2- to 10-km depth. Stage II gray quartz ??18Ofluid values range from 5.9 to 7.5 per mil, whereas ??Dfluid values calculated from the dehydration of muscovite grains and measured directly from bulk fluid inclusion analyses of stage II gray quartz have ranges of -9 to -35 and -27 to -28 per mil, respectively. Hydrothermal ore fluids were transported from greater crustal depths to the site of gold deposition during the district-scale D3 event by shallowly W dipping, reverse brittle-ductile shear zones in supracrustal rock and along the steeply east dipping trondhjemite contact. Associated subhorizontal east-west shortening caused the reactivation of the eastern trondhjemite margin and subparallel foliation, which facilitated the transport of hydrothermal fluids and the generation of gold-bearing veins and hydrothermal alteration zones in komatiite. East-west-striking fractures in trondhjemite aided the lateral migration of ore fluids away from trondhjemite margins and the formation of east-west-striking gold-bearing veins and broad alteration zones. Gold was most likely transported in the stage II fluid as bisulfide complexes. The sulfidation of trondhjemite and komatiite wall rock by the stage II fluid caused the destabilization of An bisulfide complexes and gold deposition. Potassium, Ca, and CO2 metasomatism of komatiite wall rock may have enhanced gold deposition via the acidification of the stage II fluid. The physicochemical characteristics of the Tarmoola ore fluid and relative timing of gold mineralization are consistent with the Yilgarn-wide,

  3. Tectonic fibrous veins: initiation and evolution. Ouachita Orogen, Arkansas 

    E-print Network

    Cervantes, Pablo

    2009-05-15

    , veins are characterized by veinlets (thin veins between 5 and 25 ?m thick) that parallel the vein-host interface and fibers (columns of quartz or calcite) perpendicular to the vein-host interface between 30 and 350 ?m wide. Veinlets are localized...

  4. 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 (?v = ?2) with horizontal maximum compression, ?1, 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.

  5. 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.

  6. 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.

  7. Role Of Hydrothermal System At Shallower Depth In 2.77 Ga Alteration Of Mt. Roe Basalt, Pilbara, Western Australia

    NASA Astrophysics Data System (ADS)

    Nedachi, Y.; Nedachi, M.; Taguchi, S.; Ohmoto, H.

    2004-12-01

    The sericite-chlorite alteration zone of the 2.77 Ga Mt. Roe basalt near Whim Creek, Pilbara, Western Australia, has been attracting attention if it is paleo-weathering profile (paleosol) formed under anoxic atmosphere or if it is hydrothermally altered zone by reduced fluid. It is also interesting in the standpoint of biological activity at late-Archean era, as it has been reported that the black veins in alteration zone and the sediment above it are characterized by the organic carbons with d13C values of methanogen and methanotroph. A fresh and consecutive core of Mt Roe basalt including alteration zones, which was drilled by ABDP (Archean Biosphere Drilling Project) in July 2003, gives new and more detailed insight into this concern. The core is ca. 300 m long, and is composed of amygdaloidal/massive basaltic lavas and tuffs with clastic sediments interbedded. About seventy selected samples were studied mineralogically using microscope, XRD, XGT and EPMA, and were analyzed chemically for major and trace elements using XRF and ICP-mass. The results show that (1) the core is composed of at least three lava/tuff units with different Ti/Zr and Zr/Hf ratios which are separated by thick sedimentary units, (2) the sedimentary units are comprised of sandstone, siltstone and shale, all of which are black-colored and rich in organic carbon, (3) the strongly sericitized horizons of several meters were recognized just below these sedimentary units, (4) thin sericitized layers are interbetted in amygdaloidal basalt and tuff horizons, the major part of which is associated with the fine-grained, black and organic carbon-rich quartz vein, (5) in some parts of sericitized zone, sulfide, Zn-rich and Ti-REE veins were observed, (6) all of the sericitized zone is characterizes by the depletion of Fe, Mg, Ca, Na and P and the enrichment of K, (7) several other kinds of veins, such as quartz, calcite, and chlorite, distribute across the basalt horizon, (8) organic carbons in black vein show d13C values of -40 to -50 per mil (PDB), and (9) methane was the only gas detected from the fluid inclusions in quartz vein. These observations suggest the followings, (1) there might be at least two stages of alteration; (2) the first one could be responsible for the alteration of plagioclase to calcite and mafic minerals to chlorite, for the calcite and chlorite veins, and for filling up amygdules; (3) the second one might relates to submarine hydrothermal activity at shallower depth, (4) the hydrothermal fluid might circulate through depositing sediment and top of erupted basalt/tuff, (5) methanogene could inhabitate in hydrothermal vein producing methane and made the fluid strongly reducing, and (6) methanotroph could inhabitate around seafloor. As the black hydrothermal vein was not observed in uppermost massive lava unit, the timing of this alteration would have been essentially concurrent with the volcanic activity. This is concordant with the previously reported SHRIMP age of around 2.8 Ga for euhedral apatite minerals in hydrothermal vein.

  8. Petrology of hydrothermal alteration in the Vargeão basaltic impact structure (South Brazil)

    NASA Astrophysics Data System (ADS)

    Yokoyama, E.; Nédélec, A.; Trindade, R. I.; Baratoux, D.; Berger, G.

    2011-12-01

    Impact cratering process is of primary importance in the evolution of solid bodies of the Solar System. But craters on basaltic rocks, which are the best analog for the surface of other planets and satellites, are rare on Earth. Most studies to date were done in the Lonar crater, a simple crater 1.8 km in diameter, formed on the basaltic flows of the Deccan Province (India). Recently, one medium-size complex crater was identified on volcanic rocks of the Paraná basin (south Brazil) and may provide additional analog to the craters of most rocky planets and satellites. The 12 km wide Vargeão is a very well-preserved impact structure formed on basaltic and subordinately rhyodacites flows of the Serra Geral Formation (about 133-131 Ma), which are locally intertrapped by eolian-sandstones of Botucatu Formation. The impact-related features are represented by shatter cones, breccia-veins and planar deformation features in quartz (few occurrence in the sandstones). This work is focused on the petrogenesis of the centimeter breccia-veins that are found in all lithologies. We conducted a detailed petrological study (petrography, microprobe, SEM, Raman spectroscopy, Spectroscopy of reflectance and XRD) on these veins and their host-rocks. Our results show that the veins were strongly affected by the post-impact hydrothermal fluids. The hydrothermal alteration varies geographically in the structure. On the rim area this alteration consists of total or partial substitution of the melt matrix by quartz, calcite, iron oxides and clay minerals. At the central area, the alteration mineral assembly is composed of quartz, iron oxides, zeolites, clay minerals and rarely calcite. Usually, the alteration shows a zoned setting, which also varies locally. The nature of occurrence of second mineral identified in the context of post-impact hydrothermal alteration of impact craters on basalt represent a critical interpretation to interpret alteration signature of impact craters and the old Noachian terrains of Mars. The interpretation of these signature remain controversial. These signature may result from the excavation of globally altered volcanic material during a warm and wet Mars, or alternatively may be more or less exclusively the results of impact-associated hydrothermal alteration. Our results at Vargeão may be used to assess these different hypotheses.

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

    SciTech Connect

    Cummings, M.L.; Bull, M.K. (Portland State Univ., Oregon (USA)); Pollock, J.M. (Reed Coll., Portland, OR (USA)); Thompson, G.D. (Pioneer Metals Corp., Ruidoso, NM (USA))

    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.

  10. Dike intrusion controls on permeability and hydrothermal circulation of oceanic crust at IODP Hole 1256D

    NASA Astrophysics Data System (ADS)

    Gilbert, L. A.; Tartarotti, P.; Fontana, E.; Bona, M. L.; Gross, D.; LaPier, G.; Dempsey, C.

    2012-12-01

    We examine the hydrothermal structure of the lava-dike transition zone in oceanic crust of Integrated Ocean Drilling Program (IODP) Hole 1256D using detailed sample measurements of permeability, porosity, metamorphic minerals, and structures. The transition zone consists of basaltic sheet and massive flows, a cataclastic unit, and hyaloclastitic breccias. Structural investigations show that this transition occurs through a larger depth interval than that previously defined, extending 254 m upward from the top of the Sheeted Dike Complex (811.4 to 1065.7 meters below seafloor (mbsf)). Through the transition zone, models predict a general decrease in permeability, based on a corresponding decrease in porosity with depth. Laboratory measurements of physical properties show porosity decreases drastically, as does permeability. Thin sections reveal no open pore space, and all structures are filled: veins (mm- to cm-thick) or sets of parallel veins or vein networks, Riedel-deformation bands, cataclasites (quartz, chalcedony, and calcite are the main secondary minerals; hyaloclastic breccia hosts sulfides (mainly pyrite) and is cemented by chalcedony, quartz, calcite, anhydrite, and minor amphibole. The dip angle of planar structures (including cataclasites) show an average downdip increase, thus such sub-vertical structures may represent original cooling fractures and/or might be related to the regional tectonics (i.e., extensional tectonics of the rift zone) or to the local tensional stress field created at the top of the dikes as a direct consequence of dike intrusion. Since this transition zone is located near the boundary between the Low Temperature Alteration Zone (above) and the Hydrothermal Alteration Zone (below), we postulate that fracturing and hydrothermal alteration in the investigated crustal interval likely occurred during dike intrusion. Consequently, the lower part of the lavas (below 811.4 mbsf or 561 meters sub-basement) seems to mark a boundary layer between different stress fields, permeability regimes, and metamorphic imprints.

  11. 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

  12. 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 ?-FeO(OH), lepidocrocite ?-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 active hydrothermal circulation produced primary mineral assemblages, including Fe sulfides, and was succeeded by a period dominated by oxidation and low-temperature hydration of primary minerals by surface waters. Active hydrothermal circulation can enable the rapid delivery of nutrients to microbes. Nutrient availability following the cessation of hydrothermal circulation is likely more restricted; therefore, the biological importance of chemical energy from hydrothermal mineral deposits increases with time. Weathering of primary hydrothermal deposits and dissolution and reprecipitation of mobile weathering products also create many potential habitats for endolithic microbes. They also provide a mechanism that may preserve biological materials, potentially over geological timescales. PMID:21767151

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

    NASA Astrophysics Data System (ADS)

    Sonntag, Iris; Hagemann, Steffen

    2010-05-01

    Detailed petrographic as well as hyperspectral analyses using PIMA (Portable Infrared Mineral Analyser) and geochemical (major, trace and rare earth elements) studies were conducted on samples of the epithermal, low sulfidation Co-O mine (47,869 ounces gold produced in 2009 with an average grade of 13.3 g/t gold) and district in Eastern Mindanao (Philippines). The aims of the study were to unravel the petrogenetic origin of the various volcanic (host rocks) and intrusive rocks (potential fluid driver) as well as their relationship and influence on the hydrothermal alteration zoning and fluid chemistry. The auriferous veins at the Co-O mine were formed during two hydrothermal stages associated with the district wide D1 and D2 deformation events. Gold in stage 1 quartz veins is in equilibrium with galena and sphalerite, whereas in stage 2 it is associated with pyrite. Auriferous quartz veins of stage 1 reflect temperatures below 250° C or strong variations in pH and fO2 at higher temperatures, due to potential involvement of acidic gas or meteoric water. Cathodoluminescense studies revealed strong zonation of quartz associated with Au, presumably related to changes in the Al content, which is influenced by the pH. Plumose textures indicate times of rapid deposition, whereas saccharoidal quartz grains are related to potential calcite replacement. The geology of the Co-O mine and district is dominated by Miocene volcanic rocks (basic to intermediate flows and pyroclastics units), which are partly covered by Pliocene volcanic rocks and late Oligocene to Miocene limestones. The Miocene units are intruded by diorite (presumably Miocene in age). The epithermal mineralization event may be related to diorite intrusions. The geochemistry of all igneous rocks in the district is defined by a sub-alkaline affinity and is low to medium K in composition. Most units are related to a Miocene subduction zone with westward subduction, whereas the younger Pliocene rocks are related to the currently active east dipping subduction zone. At the Co-O mine the proximal hydrothermal alteration zone is defined by phyllic to argillic alteration displayed in sericitized to carbonated feldspar, quartz and chloritized amphiboles surrounded by a distal alteration halo displaying propylitic alteration. The alteration geochemistry of these hydrothermal altered rocks is defined by an increase in K2O and Na2O and decrease in Al2O3. However, adularia usually associated with hydrothermal alteration in low epithermal Au quartz veins, has so far not been described, which points to a K-poor magma system. PIMA hydrothermal alteration studies indicate the dominant presence of smectite rather than white mica, which supports the involvement of a K-poor hydrothermal fluid. The epithermal Co-O mine and district displays low to medium potassic magma series and a hydrothermal alteration mineralogy that is K-poor. However, the Co-O mine hosts significant amounts of epithermal gold mineralization. The recognition of poor K melts and hydrothermal alteration mineralogy associated with distinct low-sulfidation epithermal gold mineralization has important implication for exploration in the Co-O district and, potentially, also in other areas in the Philippines and worldwide.

  14. 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 ?18O (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 ?18O (?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 and volcanic pile fluids (T = 240°–315°C; ?18O = 4.3 ± 1.5‰) and are interpreted to indicate mixing between the two end-member fluids. Evidence of mixing between evolved seawater and magmatic-hydrothermal fluid within the granite complex, together with the lack of evidence for a magmatic component in fluids from the volcanic pile, suggest partitioning of magmatic-hydrothermal from evolved seawater hydrothermal systems in the Panorama VHMS system. This separation is interpreted to result from either the swamping of a relatively small magmatic-hydro-thermal system by evolved seawater or density contrasts precluding movement of magmatic-hydrothermal fluids into the volcanic pile. Variability in the salinity of fluids in the volcanic pile, combined with evidence for mixing of low- and high-salinity fluids in the massive sulfide lens, is interpreted to indicate that phase separation occurred within the Panorama hydrothermal system. Although we consider this phase separation to have most likely occurred at depth within the system, as has been documented in modern VHMS systems, the data do not allow the location of the inferred phase separation to be determined.

  15. The Investigation on Fibrous Veins and Their Host from Mt. Ida, Ouachita Mountains, Arkansas 

    E-print Network

    Chung, Jae Won

    2004-09-30

    I have studied syntectonic veins from shales and coarse calcareous sands of the Ordovician Womble Shale, Benton uplift, Arkansas. All veins are composed of calcite with minor quartz and trace feldspar and dolomite or high-Mg ...

  16. The Thermal Evolution of the Ouachita Orogen, Arkansas and Oklahoma from Quartz-Calcite Thermometry and Fluid Inclusion Thermobarometry 

    E-print Network

    Piper, Jennifer

    2012-02-14

    To understand the fluid temperature and pressure during the Ouachita orogeny, we used isotopic analysis of syntectonic veins and adjacent host material, quartz-calcite oxygen isotope thermometry and fluid inclusion analysis. The veins were...

  17. FORMATION CONDITIONS OF QUARTZ MINERALIZATION IN THE MYLONITIC ZONES AND ON THE SLICKENSIDE FAULT PLANES IN THE HIGH TATRA GRANITOIDS

    Microsoft Academic Search

    EDYTA JUREWICZ

    Temperature and pressure of quartz formation on the flat dipping slickenside fault planes covered with quartz and epidote, and quartz from veins in mylonitic zones in the High Tatra granitoid have been compared. The data, obtained by studies of fluid inclusions proved that synkinematic quartz on the slickenside fault surfaces crystallized at higher pressure and lower temperature (1.5 - 1.7

  18. 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 (?34SH2S = 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 (?18OH2O = -5.9‰ to 10.9‰, ?D = -102‰ to -87‰) of the ore-forming fluids indicate that the fluids were derived from magmatic sources and evolved by mixing with local meteoric water by limited water-rock exchange and by partly degassing in uplift zones during mineralization. While most features of the Samgwang mine are consistent with classification as an orogenic gold deposit, isotopic and fluid chemistry indicate that the veins were genetically related to intrusions emplaced during the Jurassic to Cretaceous Daebo orogeny.

  19. Varicose Veins

    MedlinePLUS

    ... skin surface ( Figure ). View larger version: In this window In a new window Download as PowerPoint Slide Figure. Types of varicose ... or superficial veins. View this table: In this window In a new window Table 1. Risk Factors ...

  20. Hydrothermal fluid evolution and ore genesis in the Arghash epithermal gold prospect, northeastern Iran

    NASA Astrophysics Data System (ADS)

    Ashrafpour, Esmaeel; Ansdell, Kevin M.; Alirezaei, Saeed

    2012-06-01

    The Arghash epithermal gold prospect is located in the Sabzevar zone near the northern margin of the Central Iranian Microcontinent. The prospect includes six gold vein systems, hosted mostly by Lower-Middle Eocene intermediate to felsic volcanic and intrusive rocks with chemical compositions characteristic of continental arc magmas. Wall rocks are variably altered to clay minerals and subordinate carbonates, chlorite, and epidote, with intense alteration confined within 1-5 m of the veins. Mineralization consists of fracture fillings with local occurrences of hydrothermal breccias, and disseminations and veinlets in the immediate wall rocks. The veins consist of quartz, carbonates, minor sulfides, and gold. Pyrite is the main sulfide mineral in the hypogene ore in all vein systems except Au-VI where abundant stibnite occurs intergrown with quartz and minor pyrite; base metal sulfides are rare. Four generations of pyrite were identified: (1) disseminated euhedral to anhedral pyrite (Py-I), with up to 430 ppm Au; (2) framboidal pyrite (Py-II) with concentric As-poor and As-rich bands and up to 960 ppm Au; (3) arsenian pyrite overgrowths (Py-III) occurring on euhedral to anhedral Py-I grains, with up to 1980 ppm Au; and (4) fracture-filling, late-stage pyrite (Py-IV) that is anhedral and barren. Homogenization and ice-melting temperatures of fluid inclusions vary from 186 to 306 °C and -0.1 to -3.2 °C in quartz, and from 169 to 287 °C and 0.0 to 2.3 °C in calcite, respectively. Laser combustion analyses indicate a narrow range of ?34S values for Pyrites I-III, between -5.8‰ and +0.1‰, consistent with a magmatic source for sulfur. Pyrite IV is highly enriched in 34S (?34S = +8.9‰ to +23.7‰), and may reflect a contribution from a source enriched in 34S, such as evaporites. The ?34S values for two stibnite samples from the stibnite-rich vein (-18.8‰ and -14.4‰) sharply contrast with those of the pyrite, suggesting a different sulfur, and possibly metal source, or strong fractionation. The ?13C values for calcite are near 1‰, which is typical of marine carbonates. The calculated ?18O values for the hydrothermal fluid in equilibrium with quartz range from +5.5‰ to +7.1‰, and the calculated ?D values of the fluid in equilibrium with illite range from -48‰ to -57‰. The fluid inclusion and stable isotope data suggest that the fluids experienced a complex history of prolonged water/rock interaction, boiling, and mixing. Evidence for boiling is shown by quartz pseudomorphs after bladed calcite and coexisting vapor-rich and liquid-rich fluid inclusions. Water/rock interaction is supported by the occurrence of sulfides and anomalous concentrations of gold in the altered wall rocks adjacent to veins. The alteration and ore mineralogy, textures, fluid inclusion data, and calculated fluid isotopic composition are more consistent with the described characteristics of low-sulfidation epithermal deposits.

  1. Radiogenic hypothesis of formation of periore zones of hematitization in hydrothermal uranium deposits

    SciTech Connect

    Tkacheva, T.V.; Shmariovich, E.M.; Rekharskaya, V.M.; Lazunov, P.Ya.

    1984-02-01

    Halos of hematitization generally occur in the peripheral, more dense areas surrounding impregnated pitchblende ores, in rocks surrounding veinlets of pitchblende and in the gouge of these veinlets. The breadth of the reddening halo in the rocks can range from fractions of a millimeter to tens of meters. Developing at the edges of oxides and silicates of uranium (IV) and forming the outermost zone, hematite and goethite are present as finely dispersed particles impregnating grains of feldspar and sometimes quartz, chalcedony, calcite and replacing ferrous iron minerals such as chlorite, ankerite, siderite, biotite, pyrite, magnetite and ilmenite. In the immediate vicinity of the ore veins and phenocrysts of pitchblende, an additional quantity of modal iron is often found as oxide, indicating that this element has been carried in and precipitated as a result of oxidation or alkalization of hydrothermal solutions. 15 references, 1 figure.

  2. Revelation of stepped dislocations in amethyst crystals by hydrothermal etching

    Microsoft Academic Search

    M. S. Josut; M. A. IrryncHrN

    Triangular etch pits on rhombohedral surfaces due to hydrothermal etching are reported. Our experiments show that the hydrothermal etch pits on rhombohedral surfaces of amethyst have the same dislocation origin they have for quartz. We demonstrate that for a good number of cases successive etching results in the development of another pit away from the geometrical center of the original

  3. Low Sulphide Mineralisation of the Sudbury Igneous Complex, Canada: Examples of Fractionated Magmatic or Hydrothermal Systems?

    NASA Astrophysics Data System (ADS)

    White, C.; Mungall, J.; Spooner, E.

    2009-05-01

    Low Sulphide mineralisation occurs within the footwall of the Sudbury Igneous Complex. Samples of mineralised material have been collected from five properties and analysed using petrographic, microthermometric, point and bulk geochemical techniques. Two distinct mineralisation types have been identified for the North range (NR), a magmatic chalcopyrite (ccp) + millerite (mi) + pentlandite (pn) ± pyrrhotite (po) assemblage displaying epidote + chamosite + actinolite rich margins and haloes; and a hydrothermal ccp + mi + pyrite (py) + quartz + carbonate assemblage. South range (SR) mineralisation displays the same pattern with a po + pn + ccp ± cubanite magmatic assemblage and a hydrothermal ccp + po + pn + quartz + carbonate assemblage. Both types display a preference for exploiting lithological contacts, structures, fabrics, granophyric veins and Sudbury breccia matrix - clast contacts; and occur as cm and mm scale veins, blebs and disseminations. Analysis of mineralised material has revealed elevated precious and semi-metal concentrations dissolved within sulphides and as discrete crystals, intergrowths or aggregates of Pt, Pd, Au and Ag bismuthinides, tellurides, arsenides, antimonides, selenides and combinations thereof. Sizes range from 1-75?m, occurring interstitially or fully enclosed in sulphides and silicates. Magmatic material displays elevated concentrations of Pd in pn, Ag in ccp and Se in all sulphides when compared to contact and ''traditional" footwall mineralisation, suggesting precipitation from a strongly fractionated sulphide liquid down to temperatures of 379 to <282oC, inferred from the presence of interstitial millerite and polydymite. Hydrothermal mineralisation displays the same elevations suggesting a link to the magmatic material, with primary fluid inclusions in associated quartz giving Th (NR) of between 350-407oC and salinities of 30-35% NaCl and 18-24% NaCl-CaCl2 and tentative Th (SR) of 350-388oC and salinities of 15-28% NaCl-CaCl2 for mineralised material . The data above will be combined with thermodynamic modelling, bulk and mineral halogen analysis, outcrop mapping, acid etching, geothermometry and geobarometry to produce a genesis and exploration model for this challenging new deposit type.

  4. 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. Millimetre- to rarely up to 10 cm-thick late veins transect the earlier quartz phases. The fine-grained vein filling is dark-reddish. It contains µm-sized quartz and, again, angular quartz fragments. All these features indicate a multiphase fragmentation and quartz precipitation history of the Fountain Range Fault. Intense fragmentation, together with fluid infiltration and quartz crystallization in pore space, led to fine-grained cataclastic and silicified masses, followed by numerous events of quartz-vein formation and, again, cataclasis probably leading to flow of particle-fluid suspensions. In general, macro- and microstructures reflect the interaction of repeated processes of fragmentation, fluid flux, quartz precipitation and cataclastic flow during the long-lasting history of the fault zone, with probably non-linear behaviour of mechanical and chemical processes.

  5. 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 trondhjemite phases. The trondhjemite phases contain numerous internal contacts indicating emplacement as composite sills. Common structural features of the composite intrusions include early xenolith phases, abundant small comagmatic dikes, fractures and veins and, in places, columnar jointing. Internal phases may differ greatly in texture from fine- to coarse-grained, aphyric and granophyric through seriate to porphyritic. Mineralogical and isotopic evidence indicates that early phases of each composite intrusion are affected by pervasive to fracture-controlled high-temperature (350-450 °C) alteration reflecting seawater-rock interaction. Trondhjemite phases contain hydrothermal-magmatic alteration assemblages within miarolitic cavities, hydrothermal breccias and veins. This hydrothermal-magmatic alteration may, in part, be inherited from previously altered wall rocks. Two of the four intrusions are host to Cu-Mo-rich intrusive breccias and porphyry-type mineralization which formed as much as 14 Ma after the main subvolcanic magmatic activity. The recognition of these Precambrian, subvolcanic composite intrusions is important for greenfields VMS exploration, as they define the location of thermal corridors within extensional oceanic-arc regimes which have the greatest potential for significant VMS mineralization. The VMS mineralization may occur for 2,000 m above the intrusions. In some cases, VMS mineralization has been truncated or enveloped by late trondhjemite phases of the composite intrusions. Evidence that much of the trondhjemitic magmatism postdates the principal VMS activity is a critical factor when developing heat and fluid flow models for these subseafloor magmatic-hydrothermal systems.

  6. Oxygen isotope fractionation in quartz, albite, anorthite and calcite

    Microsoft Academic Search

    Robert N. Clayton; Julian R. Goldsmith; Toshiko K. Mayeda

    1989-01-01

    Laboratory measurements of equilibrium oxygen isotope fractionation in quartz, albite, anorthite, and calcite have been carried out by anhydrous exchange between silicates and calcite at temperatures of 600°C and above. Exchange in these systems is as rapid as exchange between silicates and water. In this paper results are compared with published theoretical estimates as well as data derived from hydrothermal

  7. 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 albite components that reacted evolved to 0.92 as the reaction progressed. Much of the alkali feldspar albite component in the proximal facies reacted while the, primary plagioclase was still unreacted, but the ratio for these assemblages increased to 1.51 when the plagioclase entered the reaction paragenesis. Plagioclase reaction during distal propylitic alteration resulted in pseudomorphic albite mixed with illite and a loss of Na2O. CaO is lost in the distal facies as hornblende reacts to chlorite, although some calcium may be fixed in calcite. CaO is added to the proximal facies as the quantity of chlorite replacing hornblende increases and epidote and calcite are produced.

  8. What Causes Varicose Veins?

    MedlinePLUS

    ... This causes the veins to swell. Weak vein walls may cause weak valves. Normally, the walls of the veins are elastic (stretchy). If these walls become weak, they lose their normal elasticity. They ...

  9. Deep Vein Thrombosis

    MedlinePLUS

    Deep Vein Thrombosis Deep Vein Thrombosis is like a ticking time bomb — knowing the symptoms of DVD can save your life. As temperatures ... a warning about the serious dangers associated with deep vein thrombosis (DVT). This is a condition occurring ...

  10. 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 conducted in the limit of low Damköhler numbers explain the observed transition regime in competitive crystal growth for blocky-elongate veins. A mechanism for the initial formation of quartz needles is proposed. For virtual fractured rock samples we study the influence of fracture shape and opening aperture in the evolution of syntaxial (blocky-elongated vs. stretched) veins. In the case of calcite, the chemical variability of the growth process in real systems strongly influences the crystal growth kinetics and limits the significance of quantitative predictions. On the basis of the numerical studies and known parameter uncertainties, we give an assessment of the variabilities of sealing times and vein microstructures. References: F. Wendler, C. Mennerich and B. Nestler, J. Cryst. Growth 327 (2011), 189-201. A. Okamoto and K. Sekine, J. Struct. Geol. 33 (2011) 1764-1775. Three time steps in the sealing of a flat fracture with calcite, only liquid phase evolution is shown.

  11. Mineralogy and fluid inclusion study of polymetallic veins in the Madjarovo ore field, Eastern Rhodope, Bulgaria

    Microsoft Academic Search

    V. Breskovska; M. Tarkian

    1993-01-01

    Summary The formation of the Madjarovo polymetallic ore deposit is closely related to Paleogene magmatism of intermediate character represented by subvolcanic and volcanic rocks. Six stages of vein type mineralization were established: 1. quartz-pyrite-chalcopyrite with Bi-sulphosalts; 2. quartz-hematite-chlorite with gold; 3. quartz-galena-sphalerite; 4. quartz-barite-chalcedony with Sb-sulphosalts; 5. quartz-arsenic sulphosalts; 6. calcite-siderite. Ag-bearing galena and Fe-poor sphalerite are the main minerals.

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

    SciTech Connect

    Moore, J.N. [Earth Sciences and Resources Institute, Salt Lake City, UT (United States)] [Earth Sciences and Resources Institute, Salt Lake City, UT (United States); Gunderson, R.P. [Unocal Corp., Santa Rose, CA (United States)] [Unocal Corp., Santa Rose, CA (United States)

    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.

  13. 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

  14. Fluid immiscibility in late-Alpine gold-bearing veins, Eastern and Northwestern European Alps

    Microsoft Academic Search

    D. Craw; D. A. H. Teagle; R. Belocky

    1993-01-01

    Gold-bearing quartz veins fill late-Alpine brittle structures in Pennine nappes of Austria (in the Tauern window) and in northern Italy. The veins formed in the latter stages of uplift of the Alps. Fluid inclusions in veins sampled from Böckstein, Austria, and Valle Anzasca, Italy have a wide variety of compositions, ranging from aqueous brine (about 5 wt% NaCl equiv.) to

  15. 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.

  16. Timing and duration of hydrothermal activity at the Los Bronces porphyry cluster: an update

    NASA Astrophysics Data System (ADS)

    Deckart, K.; Silva, W.; Spröhnle, C.; Vela, I.

    2014-06-01

    New geochronological data from the Los Bronces cluster of the Río Blanco-Los Bronces mega-porphyry Cu-Mo district establish a wide range of magmatism, hydrothermal alteration, and mineralization ages, both in terms of areal extent and time. The northern El Plomo and southernmost Los Piches exploration areas contain the oldest barren porphyritic intrusions with U-Pb ages of 10.8 ± 0.1 Ma and 13.4 ± 0.1 Ma, respectively. A hypabyssal barren intrusion adjacent northwesterly to the main pit area yields a slightly younger age of 10.2 ± 0.3 Ma (San Manuel sector, U-Pb), whereas in the Los Bronces (LB) open-pit area, the present day mineral extraction zone, porphyries range from 8.49 to 6.02 Ma (U-Pb). Hydrothermal biotite and sericite ages are up to 0.5 Ma younger but consistent with the cooling of the corresponding intrusion events of each area. Two quartz-molybdenite B-type veins from the LB open pit have Re-Os molybdenite ages of 5.65 ± 0.03 Ma and 5.35 ± 0.03 Ma consistent with published data for the contiguous Río Blanco cluster. The San Manuel exploration area within the Los Bronces cluster, located about 1.5-2 km southeast of the open-pit extraction zone, shows both the oldest hydrothermal biotite (7.70 ± 0.07 Ma; 40Ar/39Ar) and breccia cement molybdenite ages (8.36 ± 0.06 Ma; Re-Os) registered in the entire Río Blanco-Los Bronces district. These are also older than those reported from the El Teniente porphyry Cu(-Mo) deposit, suggesting that mineralization in the late Miocene to early Pliocene porphyry belt of Central Chile commenced 2 Ma before the previously accepted age of 6.3 Ma.

  17. CO2 DRIVEN HYDROTHERMAL ERUPTIONS IN GEOTHERMAL SYSTEMS OF TURKEY

    Microsoft Academic Search

    I. Tonguç Uysal; Jian-xin Zhao; Yue-xing Feng; Suzanne D. Golding

    2009-01-01

    Substantial CO2 degassing occurs from geothermal waters in Turkey as evident from ongoing deposition of recent terrace travertines and emplacement of significant travertine vein and breccia deposits representing hydrothermal eruption products. Geochemical data indicate rapid ascent of CO2- bearing fluids without significant interaction with basement and host rocks. High-precision U-series dates of most travertine veins coincide with times of cold\\/dry

  18. Varicose vein - noninvasive treatment

    MedlinePLUS

    ... vein. The vein will harden and then disappear. Laser treatment can be used on the surface of the ... uses a light under the skin to guide treatment. This may be done along ... energy. During these procedures: Your doctor will puncture ...

  19. 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 ?Nd( T) of -1.4 for the host meta-andesites. Metavolcanic rocks and cogenetic gabbros give an age of 2757±81 Ma (1 ?) with ?Nd( T) of -0.8. This is considered the best estimate for the crystallization age of the Gameleira volcanic and subvolcanic rocks. Negative ?Nd( 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 ?) with ?Nd( 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 ?) is indicated by the Sm-Nd isochron for the biotite-sulphide veins. Similar to that for the quartz-grunerite vein, the ?Nd( 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. The geochronological data suggest that the Gameleira Cu-Au mineralization is related to a Paleoproterozoic (ca. 1.83 Ga) episode of hydrothermal activity and is not Archaean. The younger ages of ca. 1.70-1.73 might be interpreted as products of the lower blocking temperatures of biotite in relation to the Ar-Ar and Sm-Nd isotopic systems. Combined with previous geochemistry and stable isotope data, the Nd isotopic data suggest that the mineralizing fluids were derived from, or strongly interacted with, a Paleoproterozoic crustal granite, possibly similar in age and composition to the Pojuca granite.

  20. Palm Vein Authentication

    Microsoft Academic Search

    Masaki Watanabe

    This chapter discusses palm vein authentication, which uses the vascular patterns of the palm as personal identification data.\\u000a Palm vein information is hard to duplicate because veins are internal to the human body. Palm vein authentication technology\\u000a offers a high level of accuracy, and delivers the following results: a false rejection rate (FRR) of 0.01% and a false acceptance\\u000a rate

  1. Varicose vein stripping

    MedlinePLUS

    ... in the veins Improving the appearance of your leg Varicose veins that can't be treated with newer procedures ... MP, Guex JJ, Weiss RA. Sclerotherapy: Treatment of Varicose and Telangiectatic Leg Veins . 5th ed. Philadelphia, PA: Elsevier Saunders; 2011.

  2. 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.

  3. Solubility and diffusional uptake of hydrogen in quartz at high water pressures: Implications for hydrolytic weakening

    Microsoft Academic Search

    A. K. Kronenberg; S. H. Kirby; R. D. Aines; G. R. Rossman

    1986-01-01

    Attempts to introduce molecular water into dry, natural quartz crystals by diffusive transport and thus weaken them hydrolytically at T=700°-900°C and PH2O=400-1550 MPa have failed. Infrared spectroscopy of hydrothermally annealed single crystals of natural quartz reveals the diffusive uptake of interstitial hydrogen (resulting in hydroxyl groups) at rates similar to those previously proposed for intracrystalline water at high water pressures.

  4. Pelvic Vein Embolisation in the Management of Varicose Veins

    Microsoft Academic Search

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

    2008-01-01

    Pelvic vein incompetence is common in patients with atypical varicose veins, contributing to their recurrence after surgery.\\u000a Therefore, refluxing pelvic veins should be identified and treated. We present our experience with pelvic vein embolisation\\u000a in patients presenting with varicose veins. Patients presenting with varicose veins with a duplex-proven contribution from\\u000a perivulval veins undergo transvaginal duplex sonography (TVUS) to identify refluxing

  5. 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. The morning of the trip will examine the White River altered area, which includes high-level alteration related to a large, early Miocene magmatic-hydrothermal system exposed about 10 km east of Enumclaw, Washington. Here, vuggy silica alteration is being quarried for silica and advanced argillic alteration has been prospected for alunite. Clay-filled fractures and sulfide-rich, fine-grained sedimentary rocks of hydrothermal origin locally are enriched in precious metals. Many hydrothermal features common in high-sulfidation gold-silver deposits and in advanced argillic alteration zones overlying porphyry copper deposits (for example, Gustafson and Hunt, 1975; Hedenquist and others, 2000; Sillitoe, 2000) are exposed, although no economic base or precious metal mineralized rock has been discovered to date. The afternoon will be spent examining two exposures of the Osceola Mudflow along the White River. The Osceola Mudflow contains abundant clasts of altered Quaternary rocks from Mount Rainier that show various types of hydrothermal alteration and hydrothermal features. The mudflow matrix contains abundant hydrothermal clay minerals that added cohesiveness to the debris flow and helped allow it to travel much farther down valley than other, noncohesive debris flows from Mount Rainier (Crandell, 1971; Vallance and Scott, 1997). The White River altered area is the subject of ongoing studies by geoscientists from Weyerhaeuser Company and the U.S. Geological Survey (USGS). The generalized descriptions of the geology, geophysics, alteration, and mineralization presented here represent the preliminary results of this study (Ashley and others, 2003). Additional field, geochemical, geochronologic, and geophysical studies are underway. The Osceola Mudflow and other Holocene debris flows from Mount Rainier also are the subject of ongoing studies by the USGS (for example, Breit and others, 2003; John and others, 2003; Plumlee and others, 2003, Sisson and others, 2003; Vallance and others, 2003). Studies of hydrothermal alteration in the Osceola Mudflow are being used to bett

  6. Incompetent Perforating Veins are Associated with Recurrent Varicose Veins

    Microsoft Academic Search

    E. E. Rutherford; B. Kianifard; S. J. Cook; J. M. Holdstock; M. S. Whiteley

    2001-01-01

    Aims: we suspected incompetent perforating veins of having a role in the development of recurrent varicose veins in some patients. The aim was to look for an association between perforators and recurrent varicose veins.Methods: a consecutive group of patients presenting with varicose veins were examined using colour duplex ultrasonography by an experienced vascular technologist. Pathological perforating veins were defined as

  7. 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

    The thickest beds of hydrothermal manganese oxides recovered to date from the global ocean were collected from a volcanic cone in the south Pacific. In April 2005, samples were dredged aboard the R.V. Kilo Moana from a volcanic cone on the lower flank of Tulaga seamount (about 2,700 m water depth; 14° 39.222' S; 170° 1.730' W), located 115 km SW of Vailulu'u, the volcanically and hydrothermally active center of the Samoan hotspot. Additional hydrothermal manganese samples were collected off Ofu Island (dredge Alia 107), 72 km to the WSW of Vailulu'u. Manganese-oxide beds up to 9 cm thick are composed of birnessite and 10 Å manganates. Some layers consist of Mn-oxide columnar structures 4 cm long and 1 cm wide, which have not been described previously. The mean Mn and Fe contents of 18 samples are 51 weight percent and 0.76 weight percent, respectively. Elevated concentrations of Li (mean 0.11 wt. percent) are indicators of a hydrothermal origin, and distinguishes these samples, along with the high Mn and low Fe contents, from hydrogenetic Fe-Mn crusts. Other enriched elements include Ba (mean 0.14 percent), Cu (249 ppm), Mo (451 ppm), Ni (400 ppm), Zn (394 ppm), V (214 ppm), and W (132 ppm). Chondrite-normalized REE patterns show large negative Ce anomalies and LREE enrichments, both characteristic of hydrothermal Mn deposits. Small negative Eu anomalies are not typical of hydrothermal deposits and can be explained either by the absence of leaching of plagioclase by the hydrothermal fluids or by the precipitation of Eu-rich minerals, such as barite and anhydrite, at depth. The high base-metal contents indicate that sulfides are not forming deeper in the hydrothermal system or that such deposits are being leached by the ascending fluids. Textures of the thickest Mn deposits indicate that the Mn oxides formed below the seabed from ascending fluids during multiple phases of waxing and waning hydrothermal pulses. The deposits were later exposed at the seafloor by 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.

  8. 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.

  9. Quantitative constraints on the interplay of fluid properties and rock mechanics in the formation of magmatic-hydrothermal ore deposits

    NASA Astrophysics Data System (ADS)

    Weis, P.; Driesner, T.; Heinrich, C. A.

    2012-12-01

    Porphyry copper and epithermal gold are among the most abundant types of ore deposits worldwide. There is evidence that both might form in a common type of magmatic-hydrothermal system related to the crystallization of subduction-related hydrous magmas in the upper crust. Our recent numerical modelling quantitatively shows that the implementation of real non-linear fluid properties and transient feedbacks with rock mechanics are key to explain some first-order controls on their formation. The salinity of the volatiles released from the solidifying magma extends the pressure-temperature range of two- or three-phase coexistence of vapour, liquid and solid halite to significantly higher pressures and temperatures as compared to pure water, and fluid inclusion analyses and theoretical models show the importance of these phase relations for metal transport and ore precipitation. Many magmatic-hydrothermal systems like porphyry-type ore deposits have dense quartz-vein networks that were formed by hydrofracturing of the rock and that are clearly associated with ore formation. In order to quantitatively constrain the hydrology of these systems in a physically rigorous way, we developed a numerical magmatic-hydrothermal simulator that can combine an accurate model of saltwater and a transient pressure- and temperature-dependent permeability model with a transport scheme that can handle the expulsion of magmatic fluids. Generic simulations demonstrate the role of fluid and rock properties in self-organizing and stabilizing fluid flow at conditions favourable for metal enrichment to economic grades in the porphyry and epithermal environments.

  10. Metasomatic- hydrothermal processes in the Qatruyeh area, Iran: Mineralogy and trace elements geochemistry of metasedimentary rock- hosted iron indices

    NASA Astrophysics Data System (ADS)

    Rajabzadeh, M. A.; Asadi, S.

    2009-04-01

    The Qatruyeh iron indices are located at about 40 Km northeast of Neyriz, in the eastern edge of the HP-LT Sanandaj-Sirjan metamorphic belt, Zagros Mountain. Qatruyeh indices are contained within the metasedimentary rocks of the Late Proterozoic- early Paleozoic, which consists predominantly of dolomitic limestone, greenschist and quartzite. Field investigations, mineralogical studies and XRD analyses indicate that orebodies are dominated by magnetite. The structures of orebodies are mainly formed as thin layers and massive, which are located between dolomitic limestones and greenschists. Tourmaline, muscovite, chlorite, talc, martite, specularite, goethite, limonite, pyrite and chalcopyrite are present as minor minerals. The area has experienced two different stages of metasomatic- hydrothermal alterations. The iron ores were formed during the metasomatic- hydrothermal processes. Those processes are: (1) Na-Ca alteration and (2) mineralization (Oxidation-Sulfidation). The first stage of alteration follows the attainment of peak regional metamorphic condition (187± 2.6 Ma based on zircon SHRIMP U- Pb). This alteration is accompanied with Low-grade magnetite ores formation (50 % Fe2O3t), replacement textures, gradual transformation between layered ores and host rock. Wet chemistry analyses on magnetite shows that Na-Ca alteration caused increasing Cr and Cu as transition metals and Ni, Co and V were depleted. Metasedimentary rock-hosted iron deposits indicate that Na-Ca alteration increase Cu, Ni, Cr, Co, Zn as immobile elements and Na-Fe, whereas the LILE (Pb, Sr) were depleted. The formation of paragonite-tourmaline is also occurs as a part of iron deposition process in the stage. The second stage of metasomatic- hydrothermal alteration is accompanied with widespread veins and veinlets of High-grade magnetite (75 % Fe2O3t) - hematite- Quartz. Mineralization took place along host rock fractures with passage of saline, hot and oxidized aqueous fluids. Paragonite altered to muscovite in the host-rocks and ores in the stage. Sulfide replacement is generally occurred as a late stage phase.

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

    SciTech Connect

    Hulen, J.B.; Nielson, D.L. (Univ. of Utah Research Institute, Salt Lake City, UT (United States))

    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.

  12. Vein and stratabound gold deposits of northern Zaire

    NASA Astrophysics Data System (ADS)

    Lavreau, J.

    1984-04-01

    Seventy years of gold mining in the North Zaire region resulted in a total output of ca. 350 t of metal, half of this amount coming from recent placer deposits. All deposits are linked to volcano-sedimentary series and associated granitoid bodies constituting the granite-green-stone terrane of northern Zaire. The actual metallotects are tectonic shear structures cutting across various rock types and giving rise either to quartz veins or to quartz-free tabular deposits, thereby obscuring the original stratabound (or rock-type bound) character of the subeconomic mineralization. Both the Archaean magmatic activity and the late Precambrian tectonics have played a role in gold concentration.

  13. Origin of the color in cobalt-doped quartz

    NASA Astrophysics Data System (ADS)

    de Miranda Pinto, Luiz Carlos B.; Righi, Ariete; Lameiras, Fernando Soares; da Silva Araujo, Fernando Gabriel; Krambrock, Klaus

    2011-09-01

    Synthetic Co-doped quartz was grown hydrothermally in steel autoclaves at the Technological Center of Minas Gerais (CETEC), Brazil. The quartz samples, originally yellow in the as-grown state acquired blue coloration after prolonged heat treatment times at 500°C near the alpha-beta transition temperature. UV-VIS-NIR absorption spectroscopy shows the characteristic spectra of Co3+ before heat treatment. After heat treatment, the optical absorption spectrum is dominated by two split-triplet bands the first in the near infrared region centered at about 6,700 cm-1 (1,490 nm) and the second in the visible spectral range at about 16,900 cm-1 (590 nm). Both split-triplet bands are typical for Co2+ ions in tetrahedral coordination environments. From the absence of electron paramagnetic resonance (EPR) spectra, we conclude that the Co2+ found in the optical absorption spectra of the blue quartz is not due to an isolated structural site in the quartz lattice. Instead, the blue color is associated with electronic transitions of Co2+ in small inclusions in which the Co site has tetrahedral symmetry. The non-observation of polarization-depend optical absorption spectra is also in agreement with this model. The results for Co2+ in quartz are different from Co-bearing spinel and staurolite and other silicates like orthopyroxene, olivine, and beryls. The formation process of the color center is discussed.

  14. Support for varicose veins

    Microsoft Academic Search

    P H Fentem; M Goddard; B A Gooden

    1976-01-01

    A method has been devised to allow reliable comparison of different strengths and constructions of support hosiery. Five garments were evaluated for the compression they exerted on the leg and their ability to limit the distension of a model varicose vein. Stockings and tights which provide modest compression can achieve worthwhile control of vein distension.

  15. Congenital vein valve aplasia

    Microsoft Academic Search

    Gunnar Plate; Lars Brudin; Bo Eklöf; Ragnar Jensen; Per Ohlin

    1986-01-01

    Congenital vein valve aplasia is often misdiagnosed and its symptoms misinterpreted as being caused by previous deep venous thrombosis. The present article reviews the literature providing data on etiology, symptomatology, and phlebographic appearance in congenital vein valve aplasia. A personal experience with 10 cases focuses on the clinico-physiological results with compression therapy and surgical treatment of superficial venous insufficiency. Compressive

  16. Quartz crystal growth

    DOEpatents

    Baughman, Richard J. (Albuquerque, NM)

    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.

  17. 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.

  18. 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 TIB1 magmatism at 1,800 Ma. The 1,848 Ma Re-Os ages obtained from molybdenite in a quartz vein and pegmatite dyke suggests that the 1,850 Ma magmatism recorded in parts of northern Norrbotten also affected the Aitik area.

  19. Diagenesis of 1900-year-old siliceous sinter (opal-A to quartz) at Opal Mound, Roosevelt Hot Springs, Utah, U.S.A.

    NASA Astrophysics Data System (ADS)

    Lynne, Bridget Y.; Campbell, Kathleen A.; Moore, J. N.; Browne, P. R. L.

    2005-08-01

    White, vitreous, siliceous sinter dated by 14C at ˜1900 years BP is located along the crest of the Opal Mound deposit at Roosevelt Hot Springs, Utah, U.S.A. Deposition at vents resulted from the Opal Mound fault opening conduits to the surface, allowing thermal fluids to discharge. Fault movement subsequently fractured the sinter and initiated a second period of fluid discharge. Colorful silica was deposited in this later period and formed the distal slope sinter, dated at ˜1600 years BP. The sinter preserves both end-members in the mineralogical maturation of silica, from initial opal-A to mature quartz, and also records incremental intermediate steps, as revealed by X-ray powder diffractrometry and by scanning electron, optical and Raman laser microscopy. Textural and mineralogical changes from one silica phase to another transpired gradually and gradationally. During diagenesis, incremental morphological changes alternated three times through nano- to micro-particle size transitions. The three corresponding mineralogical steps comprise: (1) opal-A to opal-CT, (2) opal-CT to opal-C, and (3) opal-C to quartz. Mineralogical changes preceded all morphological changes. Each step was initiated when silica nanostructures reached a critical diameter of 200 nm. The initial starting point of fresh (modern), polymeric, siliceous sinter deposition worldwide is nano-spherical particles of colloidal opal-A. Opaline sinter at Opal Mound is slightly more mature, reflecting the beginning of the aging process, and comprises botryoidal clusters of silica microspheres (< 8 ?m diameter). The conversion from these agglomerated microspheres to opal-CT bladed lepispheres at Opal Mound is marked by the reorganization of the microspheres into randomly oriented rows (˜800 nm in length) of aligned nanospheres, up to 200 nm diameter. Each row merges into joined beads, which sharpen into classic opal-CT morphology of bladed lepispheres (˜4 ?m diameter). During this first diagenetic step, the X-ray powder diffraction trace undergoes an early shift in peak position, from ˜4.0 to 4.09 Å, lining itself up in the position of the next more advanced mineralogical state, prior to emergence of the classic opal-CT blades. In the second step, the bladed lepispheres subsequently change into rectangular nano-rods (˜50 × 100 nm long segments) during early opal-C development. During the third step of early quartz formation, the opal-C nano-rods recrystallize into groups of blocky nanostructures, each up to 200 × 300 nm. Quartz crystals grow at the expense of and pseudomorph opal-C, shown by remnant bands of blocky nanostructures at the base of the quartz crystals. Two generations of quartz crystals occur at Opal Mound: (1) diagenetic, which developed as opal-C nanostructures recrystallize to quartz; and (2) hydrothermal, formed by the injection of silica-infused thermal fluids into fractures and veins within the sinter deposit. Several silica phases commonly co-exist within individual samples. Moganite, a metastable silica phase, occurs with opal-CT, opal-C and diagenetic quartz, but is most abundant with opal-CT. Hence, the complete diagenetic continuum from opal-A to quartz is preserved within this sinter deposit. It formed in the short time span of ? 1900 years.

  20. Quartz from Allchar as monitor for cosmogenic 26Al: Geochemical and petrogenetic constraints

    NASA Astrophysics Data System (ADS)

    Pavi?evi?, M. K.; Cvetkovi?, V.; Amthauer, G.; Bieniok, A.; Boev, B.; Brandstätter, F.; Götzinger, M.; Jelenkovi?, R.; Prelevi?, D.; Prohaska, T.

    2006-10-01

    Results of a multidisciplinary study on quartz concentrates (mineralogically separated) and etched concentrates (stoichiometric quartz) from three locations at Allchar (Macedonia) are presented. The investigation of quality and composition of these quartz samples is of great interest because the same material has been previously used as monitor for 26Al Acceleration Mass-Spectrometry (AMS) erosion rate estimates. Two genetically different types of quartz are distinguished in the studied samples which petrologically can be described as hydrothermally altered dacites or quartz latites; i.e. volcanic (QV) and hydrothermal (QH) quartz with relative proportions of QH:QV around 3:2. QH is genetically related to the Allchar Sb As Tl S mineralization having very high Sb (85 785 ppm), As (7.6 78 ppm) and (Tl 3.3 4.0 ppm) contents. This type of quartz is also characterized by very high Li (129 138 ppm), Al (2424 2520 ppm) and Ti (153 219 ppm) concentrations. QV appears to be much less enriched in trace elements having Al and K contents ranging from 0 to 280 ppm and from 50 to 85 ppm, respectively. 26Al AMS measurements were done on the samples containing two genetically different types of quartz but this had no effects on the interpretation and erosion rate determinations. However, the extremely high Al concentrations in the analyzed quartz have generally negative effects, mainly by decreasing 26Al/27Al ratios and thus causing an increase of the detection limit. The disagreement between the results of 26Al AMS analyses and quantitative geomorphologic data for one location is probably caused by different geographical position with respect to the direction of cosmic rays.

  1. Lead isotope compositions as guides to early gold mineralization: the North Amethyst vein system, Creede district, Colorado

    USGS Publications Warehouse

    Foley, Nick K.; Ayuso, R.A.

    1994-01-01

    The North Amethyst vein system, which is hosted by ~27 Ma Carpenter Ridge Tuff and ~26 Ma Nelson Mountain Tuff, has two mineral associations separated by brecciation and sedimentation in the veins. The early association consists of quartz, rhodonite, hematite, magnetite, electrum, Mn carbonate, Au-Ag sulfide, Ag sulfosalt, and base metal sulfide minerals. The later mineral association cuts the Mn- and Au-bearing assemblages and consists of quartz, calcite, sericite, chlorite, hematite, adularia, fluorite, base metal sulfides, and Ag-bearing tetrahedrite. Detailed studies of the Pb isotope compositions of minerals of the vein system are described. Paragenetically early sulfide-rich vein assemblages have the least radiogenic galenas and generally also have the highest Au contents. Thus, identification of paragenetically early vein assemblages with relatively unradiogenic Pb isotope compositions similar to those of the North Amethyst area provides an additional exploration tool for Au in the central San Juan Mountains area. -from Authors

  2. Retinal vein occlusion

    MedlinePLUS

    ... complications of retinal vein occlusion may include: Focal laser treatment, if macular edema is present Injections of anti- ... cause glaucoma. This treatment is still being studied. Laser treatment to prevent the growth of new, abnormal blood ...

  3. Sericitic alteration at the La Crocetta deposit (Elba Island, Italy): interplay between magmatism, tectonics and hydrothermal activity

    NASA Astrophysics Data System (ADS)

    Maineri, Cinzia; Benvenuti, Marco; Costagliola, Pilar; Dini, Andrea; Lattanzi, Pierfranco; Ruggieri, Giovanni; Villa, Igor M.

    2003-01-01

    The La Crocetta mine near Porto Azzurro (Elba Island, Tuscany, Italy) is an important producer of raw material for the ceramic industry. Exploitation focuses on a pervasively sericitized porphyritic aplite of the Tuscan Magmatic Province, locally known as "eurite", which underwent significant potassium enrichment during sericitic alteration. Eurites are located along the hanging wall of the Elba Centrale Fault, a low-angle extensional lineament of regional significance. A later carbonatization stage, apparently associated with high-angle extensional tectonics, locally overprinted the sericitized facies. It is expressed by carbonate ± pyrite ± quartz veins, with adverse effects on ore quality. Sericitization was accompanied by addition of potassium, and loss of Na (± Ca, Fe). Rubidium was not enriched along with potassium during sericitization, contrary to what would be expected for interaction with late-magmatic fluids. New 40Ar-39Ar data from eurites provide an isochron age of about 6.7 Ma for the sericitization, whereas the age of the unaltered protolith is ca. 8.8 Ma. Field evidence indicates the Elba Centrale Fault to be the main channel for the hydrothermal fluids. On the other hand, the involvement of heat and/or fluids contributed by the Porto Azzurro pluton, which crops out in the La Crocetta area, is ruled out by field, geochemical and geochronological data (40Ar-39Ar age of Porto Azzurro =5.9 Ma, i.e. significantly younger than the sericitization event). Fluid inclusion studies suggest that sericitization was associated with a low-temperature (<250 °C) hydrothermal system. Fluids were locally boiling, of variable salinity (4-17 wt% NaCl equiv.), and contained some CO2 ( XCO2?0.027). Their ultimate source is not unequivocally constrained; meteoric and/or magmatic contributions may be possible. Low-salinity (?2.6 wt% NaCl equiv.), low-temperature (<250 °C) fluids are associated with the late carbonate veining. They are considered to be of dominantly meteoric nature because of their low salinity. In summary, sericitization at La Crocetta is regarded as the product of a detachment fault-related, low temperature hydrothermal system, resulting from the structurally controlled focusing of meteoric and possibly magmatic fluids. Hence, potential targets for exploration for similar resources are represented by aplitic bodies located in the hanging wall of Elba Centrale Fault. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00126-002-0279-2.

  4. 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 ?-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.

  5. 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 States and Indonesia, and (5) plutonic igneous rocks from the Henderson Climax-type Mo deposit, United States, and the un-mineralized Inner Zone Batholith granodiorite, Japan. These five settings represent a diverse suite of geological settings and cover a wide range of formation conditions. The main discriminator elements for magnetite are Mg, Al, Ti, V, Cr, Mn, Co, Ni, Zn, and Ga. These elements are commonly present at detectable levels (10 to > 1000 ppm) and display systematic variations. We propose a combination of Ni/(Cr + Mn) vs. Ti + V, Al + Mn vs. Ti + V, Ti/V and Sn/Ga discriminant plots and upper threshold concentrations to discriminate hydrothermal from igneous magnetite and to fingerprint different hydrothermal ore deposits. The overall trends in upper threshold values for the different settings can be summarized as follows: (I) BIF (hydrothermal) — low Al, Ti, V, Cr, Mn, Co, Ni, Zn, Ga and Sn; (II) Ag–Pb–Zn veins (hydrothermal) — high Mn and low Ga and Sn; (III) Mg-skarn (hydrothermal) — high Mg and Mn and low Al, Ti, Cr, Co, Ni and Ga; (IV) skarn (hydrothermal) — high Mg, Al, Cr, Mn, Co, Ni and Zn and low Sn; (V) porphyry (hydrothermal) — high Ti and V and low Sn; (VI) porphyry (igneous) — high Ti, V and Cr and low Mg; and (VII) Climax-Mo (igneous) — high Al, Ga and Sn and low Mg and Cr.

  6. Oxygen isotope fractionation in quartz, albite, anorthite and calcite

    SciTech Connect

    Clayton, R.N.; Goldsmith, J.R.; Mayeda, Toshiko K. (Univ. of Chicago, IL (USA))

    1989-03-01

    Laboratory measurements of equilibrium oxygen isotope fractionation in quartz, albite, anorthite, and calcite have been carried out by anhydrous exchange between silicates and calcite at temperatures of 600{degree}C and above. Exchange in these systems is as rapid as exchange between silicates and water. In this paper results are compared with published theoretical estimates as well as data derived from hydrothermal experiments. Some significant differences are found. In particular, it is difficult to reconcile all of the hydrothermal data either with theoretical calculations or with the present experimental data. The new experiments provide an internally consistent set of fractionation factors suitable for isotopic thermometry and for test of disequilibrium in natural systems.

  7. Quartz resonator processing system

    DOEpatents

    Peters, Roswell D. M. (Rustburg, VA)

    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.

  8. Dual quartz crystal microbalance

    SciTech Connect

    Dunham, G.C.; Benson, N.H.; Petelenz, D.; Janata, J. (Pacific Northwest Lab., Richland, WA (United States))

    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.

  9. Spuriousless single wavelength quartz resonators

    Microsoft Academic Search

    Y. Nagaura; K. Nagaura; Z. Nagaura

    2004-01-01

    The primary research objective is to manufacture quartz resonators that can oscillate elastic waves with a single wavelength and a precise directional performance. This objective has been the dream of many researchers since the discovery of the piezoelectric effect of quartz in 1880 by the brothers Pierre and Jacques Curie who brought into being the development of the ultrasonic and

  10. 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.

  11. Pelvic Vein Embolisation in the Management of Varicose Veins

    SciTech Connect

    Ratnam, Lakshmi A. [St. George's Hospital, Department of Radiology (United Kingdom); Marsh, Petra; Holdstock, Judy M.; Harrison, Charmaine S. [Stirling House, Whiteley Clinic (United Kingdom); Hussain, Fuad F. [Royal Surrey County Hospital, Department of Radiology (United Kingdom); Whiteley, Mark S. [Stirling House, Whiteley Clinic (United Kingdom); Lopez, Anthony, E-mail: consultant@radiologist.co.u [Royal Surrey County Hospital, Department of Radiology (United Kingdom)

    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.

  12. Hydrothermal solidification of blast furnace slag by formation of tobermorite

    Microsoft Academic Search

    Zhenzi Jing; F. Jin; T. Hashida; N. Yamasaki; H. Ishida

    2007-01-01

    Blast furnace water-cooled slag (BFWS) has been solidified using a hydrothermal processing method, in which the BFWS could\\u000a be solidified in an autoclave under saturated steam pressure (1.56 MPa) at 200 ?C for 12 h by the additions of quartz or coal\\u000a flyash. The tensile strength development was shown to depend on the formation of tobermorite and the packing state of the\\u000a formed

  13. Empirical calibration of the oxygen isotope fractionation between quartz and Fe-Mg-chlorite

    NASA Astrophysics Data System (ADS)

    Lacroix, Brice; Vennemann, Torsten

    2015-01-01

    An empirical calibration has been made of the oxygen isotope fractionation between chlorite and quartz, using samples from localities in metamorphic terrains where the formation temperature has been constrained by independent methods (e.g., fluid inclusion homogenization temperatures, mineral assemblages and petrology of the host rocks to the veins, thermodynamic modeling, and Raman spectrometry). Textural equilibrium of chlorite and quartz was a pre-requisite and the chemical composition of chlorite was determined. The chlorite analyzed had a range in Fe/Mg varying between 0.35 and 0.7. Except for pure Mg-chlorite, Fe-Mg substitution within the range measured does not change the oxygen isotope fractionation between quartz and chlorite measurably. The results support a linear correlation for chlorite-quartz fractionation over the temperature range given by this study (240-550 °C):

  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. Geochronology of hydrothermal uranium deposits and associated igneous rocks in the eastern source area of the Mount Belknap Volcanics, Marysvale, Utah

    Microsoft Academic Search

    C. G. Cunningham; K. R. Ludwig; C. W. Naeser; E. K. Weiland; H. H. Mehnert; T. A. Steven; J. D. Rasmussen

    2009-01-01

    Radiometric ages of igneous rocks and hydrothermal uranium-fluorine veins in the eastern source area of the Mount Belknap Volcanics near Marysvale, Utah, show that igneous activity occurred over a time interval of about 9 million years and that hydrothermal uranium deposits were formed about midway through the interval. Intrusive igneous activity in the central mining area began about 23 m.y.

  16. Improvement in Deep Vein Haemodynamics Following Surgery for Varicose Veins

    Microsoft Academic Search

    P. Ciostek; J. Michalak; W. Noszczyk

    2004-01-01

    Objective. To analyse the effect of superficial and perforating veins surgery on deep vein incompetence.Methods. During a six-month period between 2000 and 2001 24 patients (32 limbs) with chronic venous insufficiency (CVI) were treated. They were selected because they had varicose veins and proximal deep vein incompetence with photoplethysmography (PPG) venous refilling time (VRT) 1.5 s on duplex ultrasound. The

  17. Movement of dislocations in quartz

    NASA Astrophysics Data System (ADS)

    Murray, R. A.

    1992-04-01

    Dislocations in quartz crystals have been known to cause problems in the fabrication of resonators by the formation of etch channels. The etch channels are known to weaken the physical strength of quartz blanks and to reduce the yield in photolithographic production processes. While it is possible to reduce the etch channel density in quartz by post growth electro-diffusion, this does not reduce the dislocation density. It is suspected that dislocations contribute to acceleration sensitivity, thermal hysteresis, and possibly aging. The behavior of dislocations in quartz is also of interest to the fields of geophysics, seismology, and plate tectonics because it affects the underground movement of rock. Specifically, the movement of dislocations in quartz is the mechanism through which quartz can be plastically deformed. A large body of literature on the movement of dislocations in natural and cultured quartz has been published in various geophysical journals over the past thirty years. This paper is a review of this literature and its possible implications for frequency control.

  18. Stable isotopic and fluid inclusion indications of large-scale hydrothermal paleoflow, boiling, and fluid mixing in the Keno Hill Ag-Pb-Zn district, Yukon Territory, Canada

    Microsoft Academic Search

    J. V. G. Lynch; F. J. Longstaffe; B. E. Nesbitt

    1990-01-01

    The Keno Hill vein system of the central Yukon is restricted predominantly to the highly fractured, graphitic Keno Hill Quartzite unit of Mississippian age. Hydrothermal mineral zoning is related spatially to a Cretaceous granitic pluton which intrudes the quartzite. During mineralization, the quartzite acted as a district-scale aquifer. Subsequent erosion has exposed a 40-km long vein system, from its plutonic

  19. Cerebral and Sinus Vein Thrombosis

    MedlinePLUS

    ... User Name Password Sign In Cardiology Patient Page Cerebral and Sinus Vein Thrombosis Stephan Moll , MD ; Beth Waldron , MA From the ... from the brain is called a sinus or cerebral vein thrombosis. It is an uncommon type of clot, affecting ...

  20. Hydrothermal Energy Conversion Technology

    Microsoft Academic Search

    David W. Robertson; Raymond J. LaSala

    1992-01-01

    The goal of the Hydrothermal Program is to develop concepts which allow better utilization of geothermal energy to reduce the life-cycle cost of producing electricity from liquid-dominated, hydrothermal resources. Research in the program is currently ongoing in three areas: (1) Heat Cycle Research, which is looking at methods to increase binary plant efficiencies; (2) Materials Development, which is developing materials

  1. Epidemiology of varicose veins

    Microsoft Academic Search

    Robert Beaglehole

    1986-01-01

    The prevalence rate of varicose veins in adults varies from less than 1% in lowland New Guinea women to over 50% in women in south Wales. Within populations the prevalence increases with age, is generally greater in women, is directly related to body mass, has an inconsistent relationship with occupation, and usually increases with increasing parity. None of these factors

  2. 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

  3. 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.

  4. Mixed-layer illite\\/smectite as a paleotemperature indicator in the Amethyst vein system, Creede district, Colorado, USA

    Microsoft Academic Search

    Duane G. Horton

    1985-01-01

    Ordered illite\\/smectite is the most abundant and widespread product of argillic alteration associated with the Oligocene, epithermal, Ag-Pb-Zn-Cu-Au Amethyst vein system, southwest Colorado. Hydrothermal illite\\/smectites exhibit all Reichweite from 1 to ?3 and span the composition range from about 25% to about 3% illite.— The composition and Reichweite of illite\\/smectite vary smoothly with distance from the Amethyst vein. With increasing

  5. 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

  6. Hydrothermal alteration of Tertiary igneous rocks from the Isle of Skye, northwest Scotland

    Microsoft Academic Search

    John M. Ferry

    1985-01-01

    Hydrothermal alteration of Tertiary gabbros from Skye involved the reaction of igneous olivine, augite, hypersthene, plagioclase, magnetite, and ilmenite with aqueous fluid primarily to combinations of talc, chlorite, montmorillonite, calcic amphibole, biotite, and secondary magnetite. Lesser amounts of calcite, epidote, quartz, sphene, prehnite, and garnet also developed. During mineralogical alteration of gabbro there was a net addition to rock of

  7. The Modi Taung–Nankwe gold district, Slate belt, central Myanmar: mesothermal veins in a Mesozoic orogen

    Microsoft Academic Search

    A. H. G. Mitchell; C. A. Ausa; L. Deiparine; T. Hlaing; N. Htay; A. Khine

    2004-01-01

    The recently discovered quartz–gold veins comprising the Modi Taung–Nankwe gold district in central Myanmar are largely hosted by mudstones of the late Palaeozoic Slate belt. Mesozoic rocks of the Paunglaung–Mawchi zone separate the Slate belt from the Shan Scarp and Shan Plateau to the east. At Modi Taung 5 km of exploration adits indicate that the veins, within steeply dipping

  8. Long-term results of vein sparing varicose vein surgery

    Microsoft Academic Search

    Peter Raivio; Vesa Perhoniemi; Aarno Lehtola

    2002-01-01

    The aim of this study was to assess the long-term functional outcome of vein sparing varicose vein surgery using handheld\\u000a Doppler ultrasound (HHD). The series consisted of 171 consecutive day-case surgery patients operated on for uncomplicated\\u000a lower limb varicose veins. Venous segments considered competent were spared based on clinical examination and HHD, which was\\u000a performed preoperatively only when deemed necessary

  9. 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 quartz associated with mineralization, as well as in the deep stockwork veins, suggests that brines originating deep in the system transported the metals. The ??34S values of sulfides in magnetite (-2.3???) and of sulfate in apatite (5.4???) in unaltered quartz latite indicate that ??34S???S was near 0???. The ??34S values of coexisting alteration alunite and pyrite are 18.2??? to 24.5??? and -8.1??? to -2.2???, respectively. Deep in the system, most of the change in ??34S values occurs in the sulfates, indicating that the fluids were initially H2S-dominant, their redox state buffered at depth by equilibration with igneous rocks. However, in the main alteration zone, most of the change in ??34S values occurs in pyrite, indicating that the fluids moved off the rock buffer and became SO42- -dominant as pyrite precipitated and SO2 disproportionation produced the sulfuric acid requisite for acid leaching. The ??34S values of the late-stage barite and sulfides indicate that the system returned to high H2S/SO42- ratios typical of the original rock-buffered fluid. The ??DH2O of alunite parent fluids was near -45??? and their ??18O ranged from 7??? to -1???, depending on the degree of exchange in the alteration zone at low water-rock ratio, or mixing with unexchanged meteoric water. The low ??D values of some alunite samples are interpreted to result from postdepositional exchange with later ore fluids. Fluid exsolved fr om the magma at depth had ??DH2O and ??18OH2O values near -70??? and 10???, respectively. During and following migration to the top of the magma chamber, the fluid underwent isotopic exchange with the partially crystallized magma and its solid and cooler, but still plastic, carapace just below the transition from a lithostatic to hydrostatic pressure regime. These evolved magmatic fluids had ??DH2O and ??18OH2O values close to -40??? and 5???, respectively, prior to release into the superjacent hydrostatically pressured fracture zone, wherein the fluids separat

  10. Subgrain boundaries and slip systems in quartz

    NASA Astrophysics Data System (ADS)

    Kilian, Rüdiger

    2015-04-01

    At elevated temperatures, quartz usually deforms by dislocation glide and dislocation creep. Textures (crystallographic preferred orientations) and microstructures are commonly used to infer the kinematics and physical conditions of deformation. However, it is debatable whether a given texture, represented by a pole figure, is universally indicative of a specific deformation temperature or recrystallization mechanism or e.g. is rather related to strain. Quartz veins in synkinematic, felsic dikes from the footwall of the Mohave Wash detachment fault in the Chemehuevi Mountains are studied by EBSD, CIP and universal stage. Mm-sized quartz grains are homogeneously stretched with aspect ratios of up to 30. Minor recrystallization takes place by subgrain rotation. Three different groups of highly stretched quartz grains can be defined: Grains with peripheral c-axes at a high angle to the foliation (Z-grains), grains with central c-axes perpendicular to the lineation (Y-grains) and grains with c-axes intermediately between the former two (O-grains). The three types of grains do not show a significant difference in their aspect ratios. Bulk pole figures show a kinked single c-axes girdle with a central maximum and an a-axes maximum parallel to the lineation. Misorientation analysis and the orientation of subgrain boundaries are used to make inferences on slip systems. Z-grains are interpreted to be suitable for basal (c)-slip, Y-grains for prism {m}-slip, which is compatible with the bulk misorientation distribution function of entire grains. O-grains could be interpreted as suitably oriented for rhomb {r/z/pi/pi'} slip, however, this is not supported by the bulk misorientation distribution function. Individual subgrain boundaries in Y-grains and Z-grains expected for the 'easy' slip systems {m} and (c) with tilt character ({a} parallel boundaries with [c] or misorientation axes, respectively), are limited to small (< 2°) misorientation angles. Subgrain boundaries with higher misorientation angles relate to variable slip systems, showing tilt, twist or mixed mode character. Many of those slip systems have a low Schmid factor. O-grains rarely show subgrain boundaries that can directly be related to rhomb or rhomb-slip. Most common subgrain boundaries are tilt {a}[c]-boundaries, tilt {a}-boundaries or mixed mode boundaries, hence deformation is interpreted to occur mostly by combined {m} and (c)-slip rather than rhomb slip. Based on the homogeneous microstructure without a low temperature overprint, it is inferred that deformation took place in a rather narrow temperature range. Grains deform homogeneously, independent on their orientation with different slip systems involved. A temperature effect on the activity of individual slip system is not recognizable. Suitably oriented (c) and {m} slip systems seem to result in lattice bending rather than abundant subgrain boundaries. Subgrain boundaries related to other slip systems contribute to subgrain rotation and subsequent recrystallization but not essentially to stretching of grains and rather ensure strain compatibility. The observations indicate that many prominent subgrain boundaries might not relate to the main strain producing slip system and grain orientation does not necessarily prescribe the involved slip systems.

  11. 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

    Hydrothermal alterations form when fluids warmer than the host rocks flow through them dissolving and precipitating minerals. These fluids typically flow upwards from deeper geologic units using faults as major conduits. In some cases, hydrothermal alterations affect large (km-scale) rock volumes. One example of such process is the massive high-temperature dolostones that crop out at the Benicàssim outcrop analogue (Maestrat Basin, E Spain). In this area, seismic-scale fault-controlled stratabound dolostone bodies extend over several kilometres away from large-scale faults, replacing Lower Cretaceous limestones. The fluid responsible for such alteration is a seawater-derived brine that interacted with underlying Permian-Triassic and Paleozoic basement rocks. The estimated volume of fluid required to produce the Benicàssim dolomitization is huge, with fluid-rock ratios in the order of several tens to a few hundreds, depending on composition and reaction temperature (Gomez-Rivas et al., 2014). An open key question is what brought this warm fluid (80 - 150 ºC) upwards to a depth of less than 1 km, where the dolomitization reaction took place. The driving forces should have been able not only to provide sufficient fluid volumes at shallow depths but also to heat up the whole host rock, including the non-replaced limestones. There are two hyphoteses for driving a warm fluid upwards in the Maestrat Basin: (a) rapid release through faults of overpressured solutions in recurrent pulses and (b) thermal convection. We present a series of heat and fluid flow numerical simulations to constrain the dolomitization conditions under these two end-member cases. The results indicate that in a pulsating model the fluid must flow upwards at velocities higher than cm/s to keep their elevated temperature. Otherwise they cool down quickly, and the host rocks cannot be heated. Such velocities can be reached if the fluid flow velocity equals that of fracture propagation, as in mobile 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.

  12. Coesite as stress indicator in experimentally deformed quartz gouge

    NASA Astrophysics Data System (ADS)

    Richter, Bettina; Stünitz, Holger; Heilbronner, Reneé

    2015-04-01

    In shearing experiments conducted to study the behaviour of quartz gouge at the brittle - viscous transition, coesite was found in samples that were deformed at confining pressures of 1.0 GPa or 1.5 GPa, at temperatures between 600° C and 800° C, and at constant displacement rates of ~1.3 x 10-5 mms-1 or ~1.3 x 10-4 mms-1. The experiments were performed in a Griggs type deformation apparatus and the starting material was obtained from a hydrothermally grown single crystal. The crystal was crushed and sieved to a grain size < 100 ?m. 0.1 g of the powder, with 0.2 wt% water added, was introduced in a 45° pre-cut between alumina forcing blocks forming a ~1 mm thick shear zone. In all experiments, the confining pressures (?3)and the peak mean stresses (1/3 (?1 + ?2 + ?3) for the general case or 1/2 (?1 + ?3) for ?3 = ?2) remained below the quartz - coesite transition. Only the highest principal stresses (?1) reach the coesite stability field. With the exception of low-temperature experiments, the occurrence of coesite coincides with whether or not ?1 reached the coesite stability field. In samples deformed at 600oC coesite did not form despite the fact that ?1 reached the coesite field, indicating some temperature effect for the transformation kinetics. In two samples, ?1 crosses the quartz-coesite phase transition and stays in the coesite field at the beginning of the shearing deformation and - with ongoing weakening - crosses back into the quartz stability field at higher strains. As expected, the reverse phase transformation, from coesite to quartz, can be observed in these samples. Coesite forms as soon as ?1 comes very close to or enters the coesite stability field. Clusters of small idiomorphic tabular coesite crystals are distributed throughout the sample and are commonly aligned with the [010] direction parallel to the ?1 direction. With increasing deformation in the coesite stability field, coesite grains grow (forming up to 2 vol %) and the [010] directions rotate into parallelism with the foliation (rigid particle behaviour). Once ?1 drops below the phase transition, the coesite grains are corroded, indicating a back-transformation to quartz. A preferred growth direction of the new quartz grains with respect to the old coesite grains is not obvious but the replacing quartz grains show a constant crystallographic orientation (single crystal orientation). In conclusion, in deformation experiments, the coesite formation seems to only depend on the maximum compressive stress ?1 rather than on the confining pressure or the mean stress. ?1 controls the quartz-to-coesite transformation as well as the reverse transformation except where low temperatures slow down the transformation kinetics. Furthermore, the accuracy of ?1 values measured with solid medium deformation apparatus lies within the same error range as that of the quartz-coesite phase transitions determined with the piston cylinder apparatus.

  13. Palm Vein Authentication System: A Review

    Microsoft Academic Search

    Ishani Sarkar; Farkhod Alisherov; Tai-hoon Kim; Debnath Bhattacharyya

    2010-01-01

    This paper presents a review on the palm vein authentication device that uses blood vessel patterns as a personal identifying factor. The vein information is hard to duplicate since veins are internal to the human body. The palm vein authentication technology offers a high level of accuracy. Palm vein authentication uses the vascular patterns of an individual's palm as personal

  14. Fluid inclusions in quartz-pebbles of the gold-bearing Tarkwaian conglomerates of Ghana as guides to their provenance area

    Microsoft Academic Search

    R. Klemd; W. Hirdes; M. Olesch; T. Oberthür

    1993-01-01

    Quartz-pebbles of the early Proterozoic Au-bearing Tarkwaian conglomerates in Ghana reveal several original (inherited) pre-sedimentary\\u000a fluid inclusions. These inclusions are CO2-N2 rich and display a distinct high density (up to 1.15 g\\/cm3). The unusual high density and composition compare well with CO2-N2-rich inclusions in quartz-vein type gold deposits of the Birimian Supergroup in Ghana and Burkina Faso. This type of

  15. Color Center in Amethyst Quartz

    Microsoft Academic Search

    Gerhard Lehmann; Walter J. Moore

    1966-01-01

    Treatment with x-rays increased the intensity of color of natural amethyst up to fivefold, and an electron paramagnetic resonance spectrum was detected. The intensity of the spectrum was proportional to the intensity of the optical absorption near 545 mmu. The EPR spectrum of the color center corresponded to a positive hole trapped on a substitutional Fe3+ ion in the quartz

  16. Amorphization of ?-Quartz under Irradiation

    NASA Astrophysics Data System (ADS)

    Douillard, L.; Duraud, J. P.

    1996-12-01

    The course of radiation induced damage produced in ?-quartz by neutrons, ions, electrons or photons — commonly known as metamictization — has been re-analyzed by careful comparison of available experimental data. Specific interest was devoted to confront experimental metamict state features with current structural models. It comes out that the metamict state of irradiated quartz should exhibit some structural characteristics of the modulated structure proposed for vitreous silica. The metamictization process is consistent with a structural relaxation process of a highly defective quartz matrix. According to this new point defect analysis, structural relaxation should be triggered by a critical concentration of oxygen vacancy point defects likely to significantly lower the connectivity of the SiO{2} network. Various experimental results are interpreted by incorporating the influence of the SiO{2} crystalline polymorph and the influence of the nature of the irradiating particle to the point defect model. Nous avons étudié les modifications de propriétés et de structures de monocristaux de quartz ?, consécutives à une irradiation sévère par des neutrons, des ions, des électrons ou des photons. Ce phénomène d'altération du quartz sous irradiation porte le nom de métamictisation. Notre travail exploite les recoupements de travaux antérieurs. Une attention particulière a été portée à la confrontation entre les données structurales expérimentales disponibles sur l'état métamicte du quartz et les modèles structuraux proposés. L'état métamicte du quartz présente ainsi les caractéristiques structurales du modèle de structure modulée, avancé pour décrire la structure de la silice thermique. Le mécanisme de métamictisation procéderait par relaxation de la matrice cristalline fortement endommagée. Ce phénomène de relaxation serait initié par l'apparition de concentration critique de défauts ponctuels de type lacunes d'oxygène responsables d'une forte augmentation des degrés de liberté des tétraèdres élémentaires SiO{4} au sein du crystal. Ce modèle de défaut ponctuel permet, par la prise en compte de la nature de la forme cristalline du dioxyde de silicium et la nature du projectile utilisé, de rendre compte de l'essentiel des donnés expérimentales.

  17. Fluids and halogens at the diagenetic-metamorphic boundary: evidence from veins in continental basins, western Norway

    E-print Network

    Banks, David

    spectroscopy (AAS), inductively coupled plasma (ICP) spectroscopy and Raman spectroscopy. In addi- tion to or slightly higher than those for modern seawater, whereas the ¯uids from quartz- and calcite-dominated veins Samples of modern basinal brines generally represent waters from the upper % 4.5 km of the basin (see

  18. Linear to non-linear relationship between vein spacing and layer thickness in centimetre- to decimetre-scale siliciclastic multilayers from the High-Ardenne slate belt (Belgium, Germany)

    NASA Astrophysics Data System (ADS)

    Van Noten, Koen; Sintubin, Manuel

    2010-03-01

    Typical spacing distributions have frequently been described for fractures in thin sedimentary layers (<1 m). Regularly spaced fractures often result from saturation during fracture development. Spatial distribution of veins is less commonly studied although it also can show regular patterns. This study focuses on the spatial distribution of quartz veins in Lower Devonian siliciclastic multilayer sequences from the High-Ardenne slate belt (Belgium, Germany) and compares the observed vein spacing with published fracture spacing in order (i) to investigate the effect of the layer thickness to vein spacing and (ii) to understand the processes of early vein development during the late stages of burial in a sedimentary basin at the onset of orogeny. The results show that a quasi linear relationship between vein spacing and layer thickness in thin (<40 cm) competent sandstone layers, embedded in a pelitic matrix, becomes non-linear in thicker sandstone layers (>40 cm). Vein spacing tends to increase to a maximum value becoming more or less independent of layer thickness. The resemblance with fracture spacing suggests that in an unfractured rock vein saturation can occur. High fluid pressures are responsible for vein nucleation but the stress state around the initial veins controls the spacing pattern. Subsequently, in a vein-saturated rock, or the existing veins will thicken by the process of crack-sealing, or a new cross-cutting vein generation will develop in case the regional stress field changes relatively with respect to the existing veins.

  19. 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

  20. Varicose Veins - Sclerotherapy

    NSDL National Science Digital Library

    Patient Education Institute

    This patient education program explains the benefits and risks of sclerotherapy for varicose veins. It also reviews the anatomy of the cardiovascular system, symptoms, causes, preventive measures, what the procedure involves, and possible complications. This resource is a MedlinePlus Interactive Health Tutorial from the National Library of Medicine, designed and developed by the Patient Education Institute. NOTE: This tutorial requires a special Flash plug-in, version 4 or above. If you do not have Flash, you will be prompted to obtain a free download of the software before you start the tutorial. You will also need an Acrobat Reader, available as a free download, in order to view the Reference Summary.

  1. 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.

  2. Sagittal vein thrombosis caused by central vein catheter.

    PubMed

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

    2015-03-01

    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

  3. 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.

  4. Hydrothermal Synthesis of Analcime from Kutingkeng Formation Mudstone

    NASA Astrophysics Data System (ADS)

    Hsiao, Yin-Hsiu; Chen, Kuan-Ting; Ray, Dah-Tong

    2015-04-01

    In southwest of Taiwan, the foothill located in Tainan-Kaohsiung city is the exposed area of Pliocene strata to early Pleistocene strata. The strata are about a depth of five thousand, named as Kutigkeng Formation. The outcrop of Kutigkeng Formation is typical badlands, specifically called 'Moon World.' It is commonly known as no important economic applications of agricultural land. The mineral compositions of Kutingkeng Formation are quartz, clay minerals and feldspar. The clay minerals consist of illite, clinochlore and swelling clays. To study how the phase and morphology of analcime formed by hydrothermal synthesis were affected, analcime was synthesized from the mudstone of Kutinkeng Formation with microwave hydrothermal reaction was investigated. The parameters of the experiment were the reaction temperature, the concentration of mineralizer, solids/liquid ratio and time. The sodium silicate (Na2SiO3) were used as mineralizer. The results showed that the analcime could be synthesized by hydrothermal reaction above 180° from Kutinkeng Formation mudstone samples. At the highest temperature (240°) of this study, the high purity analcime could be produced. When the concentration of Na2SiO3=3~6M, analcime could be synthesized at 240°. The best solids/liquid ratio was approximate 1 to 5. The hydrothermal reaction almost was completed after 4 hours.

  5. 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 veins are affected by the precipitation, dissolution, and re-precipitation of minerals, and also by mechanical fracturing. In all of our cases we interpret a first-phase mineral dissolution stage where permeability gradually declines as the vein is blocked by inward growing minerals. Hereafter, permeability may briefly increase with the onset of internal fracturing within the vein or by a phase of mineral dissolution opening up new pathways for fluid flow. Eventually we infer that permeability will decline again as second stage minerals are deposited in the fluid flow pathways.

  6. Positronium physisorption at quartz surfaces

    NASA Astrophysics Data System (ADS)

    Saniz, Rolando; Freeman, Arthur; Barbiellini, Bernardo; Platzman, Phil

    2007-03-01

    The possibility of having positronium (Ps) physisorbed at a material surface is of great fundamental interest, since it can lead to new insight regarding quantum sticking and is a necessary first step to try to obtain a Ps2 molecule on a material host. Experimental evidence for physisorbed Ps at the surface of quartz was reported some years ago, but firm theoretical support for such a conclusion was lacking. With the FLAPW method we calculated the electronic structure and dielectric function of ?-quartz and obtained the interaction potential with a Ps atom on its surface. We show that there is indeed a bound state with an energy of ˜0.19 eV, which is reasonably close to the experimental estimates of 0.14 - 0.17 eV. A brief energy analysis in terms of the Langmuir-Hinshelwood mechanism further shows that the formation of a Ps2 molecule at quartz surface would be possible. Sferlazzo, Berko, Canter, Phys. Rev. B 3, 6067 (1985). Wimmer, Krakauer, Weinert, Freeman, Phys. Rev. B 24, 864 (1981).

  7. Hydrothermal alteration and mineralisation of the Glen Eden Mo-W-Sn deposit: a leucogranite-related hydrothermal system, Southern New England Orogen, NSW, Australia

    Microsoft Academic Search

    Alireza Karimzadeh Somarin; Paul Ashley

    2004-01-01

    The Glen Eden Mo-Sn-W deposit in north-eastern New South Wales, Australia, is an example of a leucogranite-related, low-grade, large-tonnage hydrothermal system. It occurs in the southern part of the New England Orogen and is hosted within Permian felsic volcanic rocks, intruded at depth by dykes of porphyritic microleucogranite (Glen Eden Granite). The deposit is hosted within a pipe-like quartz-rich greisen

  8. 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.

  9. 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 extrinsic hydrothermal fluid is unlikely. We propose that the orbicules formed from an immiscible hydrous B-Fe rich melt that coalesced to the orbicules, and crystallized in a eutectic manner during the last stages of crystallization.

  10. Eclogite-facies vein systems in the Marun-Keu complex (Polar Urals, Russia): textural, chemical and thermal constraints for patterns of fluid flow in the lower crust

    Microsoft Academic Search

    José F. Molina; Stefano Poli; Håkon Austrheim; Johannes Glodny; Anatolij Rusin

    2004-01-01

    Metasomatic amphibole-eclogite sequences grew in selvages of quartz veins from the Marun-Keu complex (Polar Urals, Russia) during high-pressure metamorphism. Relicts of a pre-metasomatic eclogite-facies assemblage are present in the wallrock layers as irregular patches. Wallrock interstitial quartz trails lying at a high angle to reaction fronts provide evidence for grain-scale pore channelisation which may be produced by intergranular-fluid compositional gradients

  11. Evolution of Morphology and Crystallinity of Silica Minerals Under Hydrothermal Conditions

    NASA Astrophysics Data System (ADS)

    Isobe, H.

    2011-12-01

    Silica minerals are quite common mineral species in surface environment of the terrestrial planets. They are good indicator of terrestrial processes including hydrothermal alteration, diagenesis and soil formation. Hydrothermal quartz, metastable low temperature cristobalite and amorphous silica show characteristic morphology and crystallinity depending on their formation processes and kinetics under wide range of temperature, pressure, acidity and thermal history. In this study, silica minerals produced by acidic hydrothermal alteration related to volcanic activities and hydrothermal crystallization experiments from diatom sediment are examined with crystallographic analysis and morphologic observations. Low temperature form of cistobalite is a metastable phase and a common alteration product occured in highly acidic hydrothermal environment around fumaroles in geothermal / volcanic areas. XRD analysis revealed that the alteration degree of whole rock is represented by abundance of cristobalite. Detailed powder XRD analysis show that the primary diffraction peak of cristobalite composed with two or three phases with different d-spacing and FWHM by peak profile fitting analysis. Shorter d-spacing and narrower FWHM cristobalite crystallize from precursor materials with less-crystallized, longer d-spacing and wider FWHM cristobalite. Textures of hydrothermal cristobalite in altered rock shows remnant of porphylitic texture of the host rock, pyroxene-amphibole andesite. Diatom has amorphous silica shell and makes diatomite sediment. Diatomite found in less diagenetic Quarternary formation keeps amorphous silica diatom shells. Hydrothermal alteration experiments of amorphous silica diatomite sediment are carried out from 300 °C to 550 °C. Mineral composition of run products shows crystallization of cristobalite and quartz progress depending on temperature and run durations. Initial crystallization product, cristobalite grains occur as characteristic lepispheres and granules with various surface structures. At the very initial stage of cristobalite crystallization within 2 days run duration, cristobalite shows lepispheres a few micron meters in diameter with irregular, submicron scale ridges and grooves on the surface. With the run duration up to 7 days, lepispheres change to granules with smooth surface remaining a few micron meters in diameter. Crystallinity of cristobalite lepispheres and granules corresponds to opal-CT. Euhedral quartz crystals grow with dissolution of cristobalite grains. Growth rate of cristobalite and quartz is controlled by crystallization kinetics with induction period strongly depending on temperature. Induction period of cristobalite crystallization from amorphous silica may exceed several million years at temperature below 100 °C. Crystallinity, morphology and growth rate of silica minerals occurred in various terrestrial and planetary processes are controlled by temperature and acidity of hydrothermal fluid and nucleation and growth kinetics of silica minerals.

  12. K-feldspar-muscovite-andalusite-quartz-brine phase equilibria: An experimental study at 25 to 60 MPa and 400 to 550 C

    SciTech Connect

    Frank, M.R.; Candela, P.A.; Piccoli, P.M. [Univ. of Maryland, College Park, MD (United States)] [Univ. of Maryland, College Park, MD (United States)

    1998-12-01

    Felsic magmas may evolve one or more water or chlorine-rich fluid phases which can transport heat and solutes into associated hydrothermal systems and can contribute to alteration and ore deposition. To understand the role of a high-salinity aqueous phase in the magmatic hydrothermal environment, the composition of a subcritical, vapor-undersaturated high-salinity liquid phase (brine) in equilibrium with K-feldspar-muscovite-quartz and muscovite-andalusite-quartz was determined for pressures and temperatures ranging from 25 MPa and 400 C to 60 MPa and 550 C, with total Cl (NaCl + KCl + HCl) concentrations ranging from 3.42 to 8.56 (moles of solute/kg solution). Comparison of results with previous studies conducted at higher pressures and lower-salinity aqueous phases show that the mineral stability fields in the K-feldspar-muscovite-andalusite-quartz system shift to lower KCl/KCl values with increasing salinity and decreasing pressure.

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

    SciTech Connect

    Wilson, P.N.; Parry, W.T. (Univ. of Utah, Salt Lake City (USA))

    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.

  14. Palm vein authentication technology and its applications

    Microsoft Academic Search

    Masaki Watanabe; Toshio Endoh; Morito Shiohara; Shigeru Sasaki

    2005-01-01

    This paper discusses the contactless palm vein authentication device that uses blood vessel patterns as a personal identifying factor. The vein information is hard to duplicate since veins are internal to the human body. The palm vein authentication technology offers a high level of accuracy, and delivers the following results: a false rejection rate (FRR) of 0.01%, and a false

  15. Experimental post-entrapment water loss from synthetic CO2-H2O inclusions in natural quartz

    Microsoft Academic Search

    RONALD J. BAKKER; J. BEN H. JANSEN

    1991-01-01

    Artificial fluid inclusions were hydrothermally synthesized by crack healing in natural Brazilian quartz. Two original experiments E421 and E679 with a H20-CO2 fluid were carried out at 835 K, 200 MPa, over 38 days, and at 856 K, 211 MPa, over 35 days, respectively. In both experiments homogeneous three-phase (a vapor and two liquids) fluid inclusions were synthesized with 22

  16. Varicose Veins: Endovenous Laser Treatment

    Microsoft Academic Search

    Serge R. Mordon; Marc E. Vuylsteke

    \\u000a Endovenous laser ablation (EVLA) has been developed as an alternative to surgery of great saphenous vein (GSV) and short saphenous\\u000a vein (SSV) in an attempt to reduce morbidity and improve recovery time. EVLA can be performed in an outpatient special procedure\\u000a room in the hospital. EVLA works by means of thermal destruction of venous tissues. Several wavelengths can be used:

  17. 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 the transition is multifractal (and if so, quantify the multifractal spectrum) and determine the scale dependence of long range correlations or anti-correlations. The availability of long drill holes with detailed chemical analyses and mineral abundances derived from hyperspectral data enables individual ore bodies to be characterised in a quantitative manner and constraints placed on whether the various transition are possibly critical or of some other form. We also present some simple nonlinear models that produce the multifractal character and correlation scaling relations observed in these data sets,

  18. 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 ?13CCO2 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 ?13CCO2 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.

  19. OH-defects in detrital quartz grains: Potential for application as tool for provenance analysis and overview over crustal average

    NASA Astrophysics Data System (ADS)

    Stalder, Roland; Neuser, Rolf Dieter

    2013-08-01

    OH-defects of 95 detrital quartz grains from 4 localities in North-west Germany (2 North Sea beach sands, one Triassic sandstone, and one Carboniferous sandstone) were studied with infrared (IR) microscopy. By applying novel analytical strategies, the water contribution of fluid and mineral inclusions was minimised and the amount of water incorporated as OH-point defects was quantified. The defect water concentration in all studied quartz grains ranges between 0 and 50 wt. ppm H2O with a mean value around 10 wt. ppm. Interestingly, grains from the investigated sandstones exhibit in average nearly three times higher defect water concentrations (18 wt. ppm) than the grains from the North Sea (6.5 wt. ppm). Quartz grains with extreme undulose extinction always exhibit low defect water contents and water-rich grains usually show small undulosity, but also grains with low defect water and low undulosities are common. IR spectra of the detrital quartz grains were compared to reference spectra from samples of known localities and rock types in order to identify potential sources from which the quartz grains were sampled. Most detrital quartz grains exhibit IR signature typical for granites (showing an Al-specific band at 3378 cm- 1) and regional metamorphic rocks, but also absorption bands typical for pegmatites and hydrothermal quartz (showing a Li-specific band at 3480 cm- 1) are observed. In contrast, IR signatures typical for high-pressure origin (i.e., hydrogarnet substitution with an absorption band at 3585 cm- 1) and for tourmaline-bearing rocks (showing a B-specific band at 3595 cm- 1) are subordinate to insignificant. In view of the large scatter of defect water between individual quartz grains the strategy presented here offers an option to estimate the average defect water content of quartz in the Earth's crust.

  20. 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.

  1. Fluid inclusion evidence for subsurface phase separation and variable fluid mixing regimes beneath the deep-sea PACMANUS hydrothermal field, Manus Basin back arc rift, Papua New Guinea

    Microsoft Academic Search

    David A. Vanko; Wolfgang Bach; Stephen Roberts; Christopher J. Yeats; Steven D. Scott

    2004-01-01

    Altered volcanic rocks were cored from over 350 m below the seafloor at the Papua New Guinea-Australia-Canada Manus Basin Hydrothermal Field (PACMANUS) deep-sea hydrothermal field, in the eastern Manus back arc basin. Fluid inclusions in anhydrite veins reveal phase separation and fluid mixing beneath the seafloor. The anhydrite precipitated from high-temperature fluids (150–385°C). At Roman Ruins, a site of active

  2. 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.

  3. 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.

  4. 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.

  5. Substrate effect of hydrothermally grown ZnO nanorods and its luminescence properties

    Microsoft Academic Search

    Siddhant K. Das; Surya N. Sahoo; S. N. Sarangi; P. K. Sahoo

    2012-01-01

    We report the hexagonal wurtzite crystalline structure of ZnO nanorod growth by hydrothermal chemical wet synthesis at low temperature (90°C). We have used p-Si (100), n-Si (100), ?-quartz (0001), MgO (0001) and ITO (polycrystalline) substrates to understand the growth mechanism of ZnO nanorods with a low pressure environment. X-ray diffraction study confirms the hexagonal structure of the ZnO nanorod. Scanning

  6. Hydrothermal synthesis of ?-nickel hydroxide nanocrystalline thin film and growth of oriented carbon nanofibers

    Microsoft Academic Search

    Enlei Zhang; Yuanhong Tang; Yong Zhang; Chi Guo; Lei Yang

    2009-01-01

    Novel well-crystallized ?-nickel hydroxide nanocrystalline thin films were successfully synthesized at low temperature on the quartz substrates by hydrothermal method, and the oriented carbon nanofibers (CNFs) were prepared by acetylene cracking at 750°C on thin film as the catalyst precursor. High resolution transmission electron microscopy (HR-TEM) measurement shows that thin films were constructed mainly with hexagonal ?-nickel hydroxide nanosheets. The

  7. Bicarbonate-rich fluid inclusions and hydrogen diffusion in quartz from the Lib?ice orogenic gold deposit, Bohemian Massif

    Microsoft Academic Search

    Tomáš Hrstka; Jean Dubessy; Ji?í Zachariáš

    2011-01-01

    Unusual paleofluid composition is reported for the Lib?ice orogenic-type gold deposit located in the Central Bohemian Plutonic Complex (CBPC), Czech Republic. Unexpected bicarbonate-rich fluids and their complex chemistry variations characterize primary fluid inclusions from the main gold-bearing quartz vein. A detailed microthermometry, Laser Raman Micro Spectroscopy (LRMS) and SEM cathodoluminescence study was used to understand the complex chemistry and P–T–X

  8. (U+Th)–He evidence of Jurassic continuous hydrothermal activity in the Schwarzwald basement, Germany

    Microsoft Academic Search

    Rolf S Wernicke; Hans J Lippolt

    1997-01-01

    (U+Th)–He model and isochron ages of 21 botryoidal hematites collected from the Hohberg base-metal vein system in the Triberg granite complex, Mittelschwarzwald (Germany), cover most of the Jurassic period. The possibility of quantitative 4He loss triggered by successive hydrothermal events, although conceivable for individual hematites — based on a 4He retentivity study and calculated opening temperatures of hematite for 4He

  9. 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.

  10. Fluid circulations and quartz ductile deformation in the depths of accretionary prisms: An integrated cathodoluminescence and infrared study

    NASA Astrophysics Data System (ADS)

    Palazzin, Giulia; Raimbourg, Hugues; Famin, Vincent

    2014-05-01

    To study the processes of deformation in the depths of accretionary prism, we have carried out a study in the Shimanto Belt, in Japan, considered as a fossil accretionary prism. There, the deep metamorphic terranes of the Hyuga and Morotsuka Group were pervasively deformed for conditions of ~300 ° C and 3-5 Kbars. Quartz precipitated at depth was intensely deformed by ductile shearing, enabling to unravel the micro processes of deformation in presence of abundant fluid. Cathodoluminescence (CL) analysis revealed the presence of two distinct kinds of quartz, which we interpret as associated with two distinct fluids. One kind of quartz, blue in CL, precipitates in macro veins. The other kind of quartz, brown in CL, is found in micro veins as well as plastically deformed quartz domains. The distribution and speciation of water studied with FT-IR analysis is correlated to structures. Inherited grains, free from plastic deformation, contain a larger amount of water than strongly elongated grains. In addition, small and equant recrystallized grains contain an even smaller amount of water than elongated grains. In parallel, recrystallized grains are free from optically visible fluid inclusions, which are in contrast densely distributed in inherited and elongated grains. We also observed water speciation with the presence of characteristic picks at 3380 cm and 3480 cm-1attributed to OH associated relatively with Al+3 and Li+1. All samples always show the broad band centered at 3400 cm-1 related to 'liquid-like' molecular water (H2O) in quartz but only the quartz blue in CL, present in veins, registered the signal in secondary picks. FT-IR and cathodoluminescence signals, in good agreement with each other, constitute consistent signatures of the two distinct kinds of fluids circulating at depth. Further study is required to determine the origin of these fluids. In addition, recrystallization plays a large role in redistributing water and impurities during plastic deformation. The effect on quartz rheology is unclear, as recrystallized grains are drier, hence potentially stronger, than inherited grains.

  11. Polishing and etching langasite and quartz crystals

    Microsoft Academic Search

    Sally Laffey; Mary Hendrickson; John R. Vig

    1994-01-01

    Langasite is a promising new piezoelectric material which is similar to quartz in its acoustic behavior. Little was known until recently about the methods needed to mechanically polish and chemically polish\\/etch this material. The results of polishing and etching experiments are described. Conventional quartz polishing methods, with polishing agents such as a rare earth slurry or ruby powder, did not

  12. Thermal conductivities of fused and crystalline quartz

    Microsoft Academic Search

    E H Ratcliffe

    1959-01-01

    The thermal conductivities of fused quartz and of crystalline quartz (heat-flow at 90° to the optic axis) have been measured by steady-state plate methods; the former over the range -150 to 50° C, and the latter at 28° C. The most probable thermal conductivity values of these two materials have been formulated as functions of temperature, having in mind their

  13. Ion Implantation Damage in Quartz

    NASA Astrophysics Data System (ADS)

    Macaulay-Newcombe, R. G.

    This thesis is a report on a series of measurements of ion-bombardment effects on alpha -quartz crystals. Damage was produced in alpha -quartz (single-crystal SiO_2) by bombarding with ions of ^4He ^+ to ^{209} Bi^{++} in the energy range of 15-200 keV, at both 300 K and <=50 K. The samples were analysed in-situ with Rutherford backscattering/channeling, using 1-2 MeV ^4He^+ ions; data was obtained from both the oxygen and silicon peaks, so that damage stoichiometry could be calculated. At low ion fluences (~10^ {10}-10^{11} ions/mm^2) the apparent damage level increases linearly with fluence, but at rates of about 3-19 times greater than predicted by the modified Kinchin-Pease equation. At higher fluences (~ 10^{11}-10 ^{12} ions/mm^2 ) the rate of damage increases with fluence for elastic energy deposition rates of less than ~ 0.08 eV/atom, but remains constant for greater elastic energy deposition rates. At even higher ion fluences saturation of the damage occurs. It has been observed that the analysis beam creates damage at a rate dependent on the level of damage already present in the crystal; furthermore, the damage created by the analysis ions appears to be predominantly due to the inelastically deposited energy. Strain effects seem to greatly exaggerate the level of damage indicated by simple channeling calculations. A simple model is proposed to explain both the high rates of damage production and the non-stoichiometry of the damage. The model indicates that the effects of elastic energy deposition, inelastic energy deposition, strain produced by damage, and lattice relaxation into a "quasi-amorphous" state, all contribute to the apparent damage levels synergistically.

  14. Does Hydrothermal Circulation Matter?

    NASA Astrophysics Data System (ADS)

    Stein, C. A.; Stein, S.; von Herzen, R. P.; Fisher, A. T.

    2006-05-01

    Determining Earth's energy budget and the sources and mechanisms for heat transfer within it depends largely on assumptions of the heat loss from the formation and cooling of oceanic lithosphere, which covers about 60% of Earth's surface. Recently Hofmeister and Criss (2005) have suggested that the total global heat flow is about 30 TW, about 25% less than previously estimated by Pollack et al. (1993). The main difference between the two estimates is whether the effects of heat transfer by hydrothermal circulation are included. Thermal models describe the evolution of the lithosphere by the conductive cooling of hot material as it moves away from spreading centers. The frequently used half-space (boundary layer) and "plate" models generally successfully represent heat flow, depth, and geoid values with age, and depth-dependent properties such as flexural thickness, maximum depth of intraplate earthquakes, and lithospheric thickness. However, such models overpredict the measured heat flow from ridge crest to about 65 Myr crust. This difference is generally assumed to reflect water flow in the crust transporting heat, as shown by the spectacular hot springs at midocean ridges. If so, the observed heat flow is lower than the model's predictions, which assume that all heat is transferred by conduction. Because hydrothermal heat transport is hard to quantify, heat flow is about 50% larger than directly measured. This estimate is consistent with observations of hydrothermal circulation which indicate that the discrepancy is largely a result of the water fluxing along the oceanic basement and upwelling at isolated basement highs and outcrops. Detailed studies at such areas often show high heat flow near these outcrops and low heat flow in the surrounding areas. Hence isolated measurements are biased towards lower values and underpredict the total heat flow.

  15. Life at Hydrothermal Vents

    NSDL National Science Digital Library

    Sohmer, Rachel.

    2002-01-01

    The first Web site is a NOVA Online Adventure from PBS (1). Into the Abyss decribes the "pitch darkness, poison gas, heavy metals, extreme acidity, and enormous pressure" found at hydrothermal vents, and offers a look at bizarre and fascinating creatures found in this environment. The next Web site from Exploring Earth, an online earth sciences text book, contains video clips taken during research expeditions along the Juan de Fuca Ridge (2). Ocean AdVENTure, a ThinkQuest Web site, offers a comprehensive and well-designed introduction to hydothermal vents from research tools to fauna to unsolved mysteries and more (3). Visitors can choose their own scientific adVENTure to explore hydrothermal vents in this interactive feature from the University of Washington School of Oceonagraphy Exploraquarium (4). Dive and Discover is "an interactive distance learning Web site designed to immerse you in the excitement of discovery and exploration of the deep seafloor." This Web site (5) extends a virtual invitation to join scientists aboard research cruises to the depth of the Pacific and Indian Oceans, providing daily logs, video, and other features for each expedition. The next Web site from the University of California-Berkeley offer a closer look at the "strange tube-dwelling worm" phylum found only near hydrothermal vents (6). Creature Features, provided by the University of Delaware Graduate College of Marine Science, contains descriptions and video clips of tubeworms, vent crabs, Pompeii crabs, and ancient bacteria found at deep sea vents (7). The last Web site (8) is a transcript of a June 1997 PBS NewsHour interview with science writer William Broad. Broad discusses his book The Universe Below: Discovering the Secrets of the Deep Sea, and relates the exciting opportunities for scientific exploration of the sea floor made possible by the end of the Cold War.

  16. Extrahepatic Portal Vein Obstruction and Portal Vein Thrombosis in Special Situations: Need for a New Classification

    PubMed Central

    Wani, Zeeshan A.; Bhat, Riyaz A.; Bhadoria, Ajeet S.; Maiwall, Rakhi

    2015-01-01

    Extrahepatic portal vein obstruction is a vascular disorder of liver, which results in obstruction and cavernomatous transformation of portal vein with or without the involvement of intrahepatic portal vein, splenic vein, or superior mesenteric vein. Portal vein obstruction due to chronic liver disease, neoplasm, or postsurgery is a separate entity and is not the same as extrahepatic portal vein obstruction. Patients with extrahepatic portal vein obstruction are generally young and belong mostly to Asian countries. It is therefore very important to define portal vein thrombosis as acute or chronic from management point of view. Portal vein thrombosis in certain situations such as liver transplant and postsurgical/liver transplant period is an evolving area and needs extensive research. There is a need for a new classification, which includes all areas of the entity. In the current review, the most recent literature of extrahepatic portal vein obstruction is reviewed and summarized. PMID:26021771

  17. 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 hypertension, are associated with higher morbidity and mortality risks in the short term. PMID:25755579

  18. 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

  19. Varicose Vein Treatment (Endovenous Ablation of Varicose Veins)

    MedlinePLUS

    ... approximately 1/8 inch in diameter. Laser fibers (fiber optics) or radiofrequency electrodes carry laser or electrical energy from their respective power generators into the body. top of ... vein. A laser fiber or radiofrequency electrode is then inserted through the ...

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

    SciTech Connect

    Schellhammer, Frank, E-mail: frank.schellhammer@med.uni-duesseldorf.d [University Hospital Duesseldorf, Institute of Diagnostic Radiology (Germany); Esch, Jan Schulte am [University Hospital Duesseldorf, Department of General, Visceral and Pediatric Surgery (Germany); Hammerschlag, Sascha [University Hospital Duesseldorf, Institute of Diagnostic Radiology (Germany); Knoefel, Wolfram Trudo [University Hospital Duesseldorf, Department of General, Visceral and Pediatric Surgery (Germany); Fuerst, Guenter [University Hospital Duesseldorf, Institute of Diagnostic Radiology (Germany)

    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.

  1. 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.

  2. How Can Varicose Veins Be Prevented?

    MedlinePLUS

    ... tight around your waist, groin (upper thighs), and legs. Tight clothes can make varicose veins worse. Avoid wearing high heels for long periods. ... in the veins and decreases swelling in the legs. Rate This Content: NEXT ... 13, 2014 Varicose Veins Clinical Trials Clinical trials are research studies that ...

  3. Genesis and evolution of the upper oceanic crust (ODP-IODP site 1256, East Pacific Rise): inferences from structure and composition of late magmatic veins in a lava pond

    NASA Astrophysics Data System (ADS)

    Panseri, M.

    2009-04-01

    A complete intact "in situ" section of upper oceanic crust, from extrusive lavas, through dikes into gabbros has been recently drilled for the first time in a 15 Ma old crust that formed at the East Pacific Rise with a full spreading rate of >200 mm/yr. The study area is ODP-IODP Site 1256 (6°44.2N, 91°56.1W, Pacific Ocean). Holes 1256C and 1256D have been drilled into the basaltic basement during ODP Leg 206, IODP Expeditions 309 and 312. Hole 1256D has been deepened to a depth of ca. 1500 meters below seafloor (mbsf). The upper section of the igneous basement consists of thin (<3m) basaltic sheet flows separated by chilled margins, and massive basaltic flows (>3m). The massive flows include a ponded lava flow, located near the top of both Hole 1256C and 1256D, where it has a thickness of 32m and 74m, respectively. The lava pond is interpreted as a thick lava flow delivered either on-axis or off-axis and accumulated in a topographic depression. Although very close (ca. 30m), the two holes record different structural patterns of the lava pond, probably related to different steps of the lava flow emplacement. In the lava pond, both igneous (magmatic foliation, flow-related folds, late-magmatic veins) and post-magmatic (joints, veins, shear veins, and microfaults) structures were recognized. Late magmatic veins (LMVs), which were identified as primary features typical of the lava pond, are the main goal of this work. Mm-thick LMVs are mainly clustered in the middle (290-300 mbsf in hole 1256C and 282-297 mbsf in hole 1256D) and bottom (312-313 mbsf in hole 1256C and 311-328 mbsf in hole 1256D) parts of the lava pond. Structural measurements on cores suggest that they are mostly gently dipping structures, but we also observed sub-vertical LMVs. At the bottom of the lava pond in hole 1256C, late magmatic veins are often arranged in en echelon arrays and sigmoidal pull aparts, suggesting a syn/post-magmatic shear component. Thin-section observations show that basalt including LMVs consists of plagioclase, clinopyroxene, ilmenite, and spinel. LMVs cutting basalt are filled with quartz, quartz + plagioclase intergrowth showing a granophyric texture, clinopyroxene, ilmenite, spinel, and apatite. Rarely we observed pyrite crystals at the LMV core that cut plagioclase + quartz intergrowth. Quartz + plagioclase intergrowth (with apatite) are also present in the basalt as mm-size interstitial domains or rimming plagioclase (IDs = intergrowth domains). Rare samples display IDs with interstitial K-feldspar growing around plagioclase. LMVs often show sharp contacts with basalt. Plagioclase or pyroxene crystals of the basalt may be fragmented at the contact with LMVs (brittle rheology of basalt). Differently, IDs commonly corrode plagioclase crystals, without fragmentation (ductile rheology). The composition of basalt plagioclase ranges from Ab37 to Ab62, with a main concentration around Ab50. On the contrary, plagioclase in the LMVs intergrowth as well as that in the mm-sized IDs are Na-rich (Ab64-Ab98). Mineral analyses also highlight homogeneous clinopyroxene, spinel and ilmenite, without variations in the LMVs and IDs. Clinopyroxene usually shows a Ca-poor core (mainly augite or pigeonite) and a diopsidic rim. Opaque minerals often exhibit ilmenite-ulvospinel lamellae intergrowths. EDS mapping of IDs and LMVs cutting basalt supports the previous observations. LMVs and IDs have higher Si, Na and lower Al, Ca values than basalt. This distribution is only due to albitic plagioclase concentration in LMVs and IDs. K has low and homogeneous concentrations: rarely IDs are characterized by interstitial K enrichment (K-feldspar). Incompatible (Zr, Rb, Sr, Ba), hydrothermal elements (Cu, Cl), and F are undetectable or absent. We infer that LMVs and IDs likely crystallized from a pure Si-Al-Na-(Ca) melt. K, rarely noticed in the IDs, may be related to late magmatic fluids differentiation or to subsequent hydrothermal fluids. Core description, microstructural observations, mineral compositions and EDS mapping of the stud

  4. 3-D Mohr circle construction using vein orientation data from Gadag (southern India) - Implications to recognize fluid pressure fluctuation

    NASA Astrophysics Data System (ADS)

    Mondal, Tridib Kumar; Mamtani, Manish A.

    2013-11-01

    In this paper orientations of quartz veins from the Archaean age lode-gold bearing region of Gadag (southern India) are used to determine the relative stress and fluid pressure (Pf) conditions by constructing 3-D Mohr circle. Anisotropy of magnetic susceptibility (AMS) analysis of the host massive metabasalt reveals that the magnetic foliation is NW-SE striking, which is related to early NE-SW compression (D1/D2 deformation) that affected the region. The quartz veins have a wide range of orientations, with NW-SE striking veins (steep northeasterly dips) being the most prominent. Vein emplacement is inferred to have taken place under NW-SE compression that is known to have caused late deformation (D3) in the region. It is argued that the NW-SE fabric defined the pre-existing anisotropy and channelized fluid flow during D3. The permeability was initially low, which resulted in high Pf (>?2). 3-D Mohr circle analysis indicates that the driving pressure ratio (R?) was 0.94, a condition that favoured fracturing and reactivation of fabric elements (foliations and fractures) having a wide range of orientations. This led to an increase in permeability and fluid flowed (burped) into the fractures. Resulting vein emplacement and sealing of fractures led to a reduction of Pf (vein emplacement, while fractures of all other orientations were inactive and remained sealed. As a consequence, the study area has a cluster of NW-SE oriented veins. R? is calculated to be 0.07 from 3-D Mohr circle analysis at low Pf, when fractures with NW-SE orientation only were susceptible to dilation. However, it is envisaged that any emplacement of veins in these fractures would have sealed them, thus reducing the permeability and initiating the next cycle of rise in Pf (>?2). Thus, it is concluded that the quartz veins in the Gadag region are a consequence of an interplay between conditions that fluctuated from Pf > ?2 to Pf < ?2.

  5. Relationship Between SEM-Cathodoluminescence and Trace Element Chemistry of Quartz in Granitic Igneous Rocks of the Oslo Continental Rift

    NASA Astrophysics Data System (ADS)

    Jacamon, F. P.; Larsen, R. B.

    2005-12-01

    Numerous granitic intrusions were emplaced in the Oslo area during the main rifting episode (275-240 Ma). The Drammen biotite-granite and Eikeren-Skrim alkali-feldspar granite (ekerite) represent two of the most evolved rock types related to this period of plutonic activity.This study documents the textural and chemical features of the different generations of quartz (Qz) present in the two granites, in relation with the igneous and hydrothermal processes at the origin of their formation.Both granites suffered pervasive alteration by magmatic and hydrothermal (sub-solidus) fluids. Contrary to other minerals, primary igneous quartz is well preserved and revealed by SEM-cathodoluminescence (SEM-CL) images. Several generations of secondary quartz are also recognisable and clearly related to late magmatic and/or subsolidus fluid infiltrations.Four quartz types can be categorised by SEM-CL luminescence and texture:Type 1: Bright primary quartz frequently showing oscillatory growth zoning from core to rim, in the form of alternating bright and dark ring-liked sectors reflecting compositional variations of the crystallising melt.Type 2: Light grey up to hundreds ?m wide diffuse alteration zones, which follow grain boundaries and open cracks cutting through grains of Qz type 1.Type 3: Usually darker than Qz type 2. Contrary to Qz type 2, not necessarily directly associated with macroscopic fracturing features. Qz type 3 is featured by irregular patterns cutting through Qz type 1 and 2 and seems to be the result of dissolution/recrystallisation processes, possibly through a network of micro cracks related to the major fluid channelling fractures.Type 4: Narrow cracks and patches of black Qz crosscutting all the other types.EPMA in situ analysis of the different quartz generations confirm that the intensity of luminescence of quartz is strongly positively correlated to the presence of specific trace elements in quartz like Ti and Al. Hence the different quartz types mentioned before can be distinguished by levels of luminescence and trace element chemistry. Qz type 1 contains about 250 (200-350) ppm Ti and 130 (80-160) ppm Al, whereas Qz type 2 and 3 have overlapping concentrations averaging 60 (10-120) ppm Ti and 90 (50-130) ppm Al. Qz type 4 was not analysed due to the narrowness of the structures. These results document that quartz alteration by percolating fluids has a purifying effect, leaching Ti and Al out of the quartz by diffusion (Qz type 2)and dissolution/recrystallisation (Qz type 3).SEM-CL textures and chemistry of quartz help to understand the complex magmatic and hydrothermal history of these granites, whose original magmatic picture is strongly overprinted and blurred by pervasive fluid-related alteration features.

  6. Interactions between magma chambers and hydrothermal systems: Oceanic and ophiolitic constraints

    NASA Astrophysics Data System (ADS)

    Nehlig, P.

    1993-11-01

    A compilation of published exit temperatures and salinities for seafloor hydrothermal fluids, along with fluid inclusion data on oceanic and ophiolitic rocks, shows that ridge axes hydrothermal systems are generally characterized by maximum temperatures around 300 - 360 C, thus clearly being in the one-phase field. They overlie a lower system marked by the generation of highly saline brines at high temperatures. The brines may have originated either when seawater approached the top of the magma chamber or more probably as exsolution products of the differentiated melts that typify the roof of oceanic magma chambers. In ophiolites, the brines typically occur within the transition zone between the sheeted-dike complex and the plutonic sequence, i.e., on top of magma chambers. This transition zone, relatively well known from ophiolite studies (Oman, Troodos, Bay of Islands, Josephine), is characterized by mutually intrusive relationships between gabbro, plagiogranite, and dikes and xenoliths of altered diabase within plagiogranite and gabbro. In fast to medium spreading ophiolites (Oman) it is the locus of a major downward decrease in the density of hydrothermal veins and alteration. The vein system is strongly anistropic and shows a well-marked preferred vertical along-stike orientation. The underlying cummulates are almost unaltered and exhibit only a diffuse net of amphibole veins, while the overlying sheeted-dike complex is densely veined and pervasively altered. This zone is marked by major gradients in the physical parameters over short distances: temperature (several degrees Celsius per meter), pressure (several hundred kilopascals), transition from brittle to ductile. In steady state systems, direct interactions between the magma chamber and the hydrothermal system are restricted to this zone, characterized by exsolution of magmatic volatiles into the hydrothermal system and the incorporation of hydrothermal fluids into the magma chamber by digestion of altered roof rocks. Complications to this stready state model resulting from a non-steady state magma chamber (e.g., Josephine ophiolite) are mainly the development of late stage faulting and more pronounced retrogressive alteration.

  7. 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 U deposits around Mount Isa and may also suggest a relationship between U mineralization and regional Cu mobilization during the Isan orogeny. Our work suggests that non-conventional geochronometers should be used only if additional geological information and geochemical data (e.g., mineral chemistry, trace elements) are available to evaluate any resulting age calculations.

  8. En Echelon Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Ryan, M. P.; Carr, P. M.; Daniels, D. L.; Sutphin, D. M.

    2005-12-01

    En echelon hydrothermal systems develop within the porous rocks that surround, in three-dimensions, their distinctive plan-form and cross-sectional basaltic intrusion geometry. Examples that span several (self-similar) spatial scales include the en echelon off-set area of the East Rift Zone of Kilauea Volcano, Hawaii; the Northeast Rift Zone of Mauna Loa Volcano; the intrusive-eruptive fissures of the Krafla Central Volcano, Northeast Iceland; the ensemble of the three Icelandic central volcanoes Theistarekir-Krafla-Fremrinamur; major segments of the East Pacific Rise and the Mid-Atlantic Ridge; and several paleo-hydrothermal systems of the Mesozoic basins of eastern North America, including the Culpeper Basin. An en echelon hydrothermal system comprises two or more en echelon--arranged magma-filled fractures enclosed in a fluid-saturated porous matrix. Blocks of country rock between individual offset fracture segments are similarly porous and fluid-saturated. In 3-D, the system resembles the fan blades of a turbine rotor, with blades (dikes) emanating from a deep "master" fracture and turning smoothly in response to the local variations in the least compressive regional stress component. The primary geometric, hydrologic and thermal attributes of the system (on a horizontal plane) include dike thickness, dike-to-dike offset and overlap, the (initial) intrusion temperature, duration of magma flow, dike widths and lengths, the mean seepage velocity of regional subsurface aqueous fluid flow, and the mean flow azimuth in relationship to the plan-form geometry of the en echelon array. Finite element single phase models in horizontal cross-section have been developed for dike widths of 100 m, dike lengths of 1,500 m, overlaps of 500 m, dike-to-dike offsets of 500 m, intrusion temperatures of 1,200 C, horizontal seepage fluxes imposed at the sides of ~ 1,000 g cm-2 yr-1, and a matrix permeability of 10-14 m2. The regional flow field has been parameterized in dike-orthogonal, dike-parallel, and 45 degree angles of attack with respect to the major axes of the individual dikes within the en echelon array. Depending on the magnitudes and geometric arrangement of key system attributes, an en echelon hydrothermal system may either act as an efficient thermal radiator, effectively shedding heat to the surroundings, or may it act as an effective heater, thermally enhancing the environment between neighboring dikes in 3-D. Conditions that promote the efficient loss of heat include thin dikes of short length, large dike-to-dike offset, high matrix fluid velocities, and regional flow azimuths that are orthogonal to the individual dikes. Conditions that promote differential heating between the dikes include wide dikes with maximal overlap and minimal offset, low regional flow velocities and "angles of attack" of the regional flow field that provide for maximum hydrodynamic "shelter" for individual dikes within the interior of the en echelon array.

  9. The analysis of a hydrothermal breccia system, Mount Painter Inlier, South Australia

    NASA Astrophysics Data System (ADS)

    Weisheit, Anett; Bons, Paul D.; Elburg, Marlina A.

    2010-05-01

    A large hydrothermal breccia system is located in the Mt. Painter Inlier (South Australia), which is a small Mesoproterozoic basement block composed of metamorphics, as well as deformed and undeformed granitoids. The Mt. Painter Inlier and surrounding Adelaidean Sequence rocks underwent folding, faulting and associated metamorphism during the ~500 Ma Delamerian Orogeny. The first and major magmatic-hydrothermal event was dated at about 440 Ma (Elburg et al., 2003). It involved several stages of alteration and brecciation: 1) Intrusion of S- and I-type granite and associated pegmatites. 2) Extensive K-feldspar alteration of all lithologies, resulting in a granite-like feldspar-quartz rock. 3) Localisation of fluid flow to form extensive feldspar-rich and/or chlorite-alteration breccia zones. 4) Formation of uranium-bearing magnetite/haematite breccia bodies. Uranium precipitation is probably related to the oxidation of magnetite to haematite. The area cooled down to ca. 170°C at about 310 Ma (U/Th-He age) and subsequently a second, near-surface hydrothermal event overprinted and reworked the older breccia and alteration zones. It involved remobilisation of haematite, extensive quartz precipitation and the partial removal of uranium. An age of about 220 Ma was obtained by Rb/Sr dating of associated quartz and fluorite. Detailed mapping and hyperspectral analyses show that fluids followed pre-existing structures, such as pre-Delamerian and Delamerian foliation, folds and faults, even though most of these faults appear not to have been active during hydrothermal activity. Elburg, M.A., Bons, P.D., Foden, J. and Brugger, J. (2003): A new defined Late Ordovician magmatic-thermal event in the Mt Painter Province, Northern Flinders Ranges, South Australia, Australian Journal of Earth Sciences, 50:611-631

  10. 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

  11. Quartz-enhanced photoacoustic spectroscopy: a review.

    PubMed

    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. 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

    Microsoft Academic Search

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

    2010-01-01

    The Samgwang mine is located in the Cheongyang gold district (Cheonan Metallogenic Province) of the Republic of Korea. It\\u000a consists of eight massive, gold-bearing quartz veins that filled NE- and NW-striking fractures along fault zones in Precambrian\\u000a granitic gneiss of the Gyeonggi massif. Their mineralogy and paragenesis allow two separate vein-forming episodes to be recognized,\\u000a temporally separated by a major

  13. 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

    Microsoft Academic Search

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

    2010-01-01

    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

  14. The optical properties of amethyst quartz

    Microsoft Academic Search

    C. V. Raman; K. Banerji

    1925-01-01

    Circularly-polarized waves of light, in passing through a section-plate of amethyst quartz, would obviously be retarded unequally in the alternate laminae having right- and left-handed optical activities. Diffraction effects must therefore arise, and these can actually be observed even in almost colourless varieties of the quartz. The section-plate behaves in effect as a phase-change diffraction grating, and the question of

  15. Method of making a quartz resonator

    DOEpatents

    Vig, John R. (Colts Neck, NJ); Filler, Raymond L. (Freehold, NJ); Peters, R. Donald (Pinnellas Park, FL); Frank, James M. (Seminole, FL)

    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.

  16. Quartz resonator fluid monitors for vehicle applications

    SciTech Connect

    Cernosek, R.W.; Martin, S.J.; Wessendorf, K.O.; Terry, M.D. [Sandia National Labs., Albuquerque, NM (United States); Rumpf, A.N. [Ktech Corp., Albuquerque, NM (United States)

    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.

  17. Hydrothermal vents is Lake Tanganyika, East African Rift system

    SciTech Connect

    Tiercelin, J.J. [Universite de Bretagne Occidentale, Brest (France)] [Universite de Bretagne Occidentale, Brest (France); Pflumio, C.; Castrec, M. [Universite Paris VI, Paris (France)] [and others] [Universite Paris VI, Paris (France); and others

    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.

  18. SAW temperature sensor on Quartz.

    PubMed

    Zhgoon, Sergei; Shvetsov, Alexander; Ancev, Ivan; Bogoslovsky, Sergei; Sapozhnikov, Gennadiy; Trokhimets, Konstantin; Derkach, Mikhail

    2015-06-01

    For biomedical applications, narrow temperature range and high sensor accuracy requirements define the need for high temperature sensitivity. Wireless SAW sensors connected to antennas need a reference element to account for changes in electromagnetic coupling between the transmitter and receiver antennas. A pair of sensors with different temperature sensitivities may serve as a self-referenced sensor assembly. This justifies the need for materials with useful SAW resonator properties and with the largest difference between temperature coefficients of frequency (TCF) for a resonator pair on a single substrate. We have identified several cuts of quartz having useful properties with a TCF difference up to 140 ppm/°C for a pair of resonators on a single substrate. As a rule, placing such resonators on a single substrate requires their rotation by up to 90° relative to each other. The limited range of cuts presents a unique opportunity to place both resonators along the X+90° direction with one resonator using Bleustein-Gulyaev-Shimizu (BGS) waves (with electrodes placed along the x-axis) and the other one (with electrodes inclined by about ±10° to the x-axis) using quasi-Rayleigh waves. These cuts are close to the 70°Y cut where a high TCF difference is reached together with acceptable characteristics of the resonators. Resonators were designed for all useful cuts (including the 70°Y cut) and tested. The use of different periods in reflectors and interdigital transducer (IDT) together with individual choice of gaps between reflectors and IDT meant achieving low spurious content in resonator responses. The quality factors reached values up to 3500 at central frequencies around 915 MHz for both BGS and quasi-Rayleigh types of waves. The measured difference of the TCF is about 138 ppm//spl degC on 70°Y cut that is close to the calculated value. PMID:26067041

  19. 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.

  20. Thrombosis of the popliteal vein

    Microsoft Academic Search

    Hans-Erich Schmitt; Michael J. Mihatsch

    1992-01-01

    Among 3,307 consecutive patients (3,556 legs) with deep venous thrombosis, 54 (1.5%) showed an isolated thrombus of the popliteal\\u000a vein on phlebography. The majority of those had a history of “effort” or long lasting flexion during air or bus travel. Forty-four\\u000a percent suffered from pulmonary embolism as the first sign of deep venous thrombosis. Functional phlebography demonstrated\\u000a the primary site

  1. Geochemistry of the quartz dioritegranite association, Roded area, southern Israel

    E-print Network

    Dov, Avigad

    Geochemistry of the quartz diorite­­granite association, Roded area, southern Israel Ron Bogoch a Accepted 20 May 2002 Abstract The Roded quartz diorite of southern Israel formed by fractional contained within the quartz diorite, formed in irregularly spaced ``pockets'' near the end of quartz diorite

  2. 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.

  3. 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 during transient boiling or rock-water exchange (fracturing) events. ?? 1990.

  4. 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 ?m 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 CL spectra ranging from 300 to 800 nm in 1 nmsteps at accelerating voltage of 15 kV and beam current of 1.0 nA. Most of the quartz grains have double emission peaks at around 450nm in blue region and at around 620 nm in red region. The emission components of these spectral peaks have been assigned by deconvolution method using Gaussian curve fitting, and individual contributions were quantitatively evaluated by the integral intensities of the components.

  5. Gold and platinum group elements in cobaltarsenide ores: Hydrothermal concentration from a serpentinite source-rock (Bou Azzer, Morocco)

    Microsoft Academic Search

    M. Leblanc; W. Fischer

    1990-01-01

    Summary The cobalt-arsenide ores of Bou Azzer are located along the borders of serpentinite massifs (Upper Proterozoic ophiolite complex) in carbonate-quartz lenses resulting from hydrothermal carbonate alteration of serpentinite. The cobalt ores contain an average gold content of 5–20 ppm; gold is mainly located in skutterudite (120 ppm av.), whereas the Fe-arsenide (loellingite) contains < 1 ppm Au. Similarly the

  6. Mineralogy, paragenesis and textures associated with metasomatic- hydrothermal processes, Qatruyeh area, Sanandaj- Sirjan zone, SW Iran

    NASA Astrophysics Data System (ADS)

    Asadi, S.; Rajabzadeh, M. A.

    2009-04-01

    The Qatruyeh area is located at about 40 Km northeastern of Neyriz region, in the eastern edge of the high P- Low T metamorphic Zagros orogenic belt. The studied area principally includes outcrops of green schist facies metamorphic rocks that are thrusted over the Neotethyan ophiolites. Hydrothermal activities occurred episodically in the Mesozoic era . The textural relationships, mineral assemblages and X- Ray diffractions have recognized two different stages of hydrothermal alteration during mineralization. The Mineralization was largely controlled by striking faults and host rock layers. Three different types of magnetite are distinguished in microscopic investigation. The First is euhedral to subhedral, partly replacement by martite with exsolved ilmenites. The Second reveals myrmekite like textures and the last type includes layered magnetite. All of the types are related to replacement textures such as psedomorphism, widening of a fracture filling, irregulare or vermicular intergrowths, islands of unreplaced host rock, cusp or caries, nonmatching walls or borders of a fracture and rims of one mineral penetrating another along its crystallographic direction. X- Ray analyses indicate oxide minerals (Magnetite, Hematite, Maghemite, Specularite, Goethite, Limonite and Ilmenite), Silicate minerals (Tourmaline-shorl and dravite-, Epidote, Chlorite, Actinolite, Titanite, Paragonite, Talc, Muscovite and Quartz), Carbonate minerals (Siderite and Malachite) and Sulfide minerals (Pyrite and Chalcopyrite-minor-) as major phases. The mineral paragenesis and textures show two different stages of metasomatic- hydrothermal alteration. The first stage alteration (Sodic- Calsic) accompanying with mineral paragenesis of Magnetite+ Tourmaline+ Titanite+ Paragonite and the second stage of alteration (Solfidation- Oxidation) follows with Magnetite+ Hematite+ Quartz

  7. A comparison of fluids causing post-depositional hydrothermal alteration in Archaean basement granitoids and the Witwatersrand Basin

    Microsoft Academic Search

    R. Klemd; Universitfit Bremen

    1999-01-01

    Summary Some Archaean granitoids occurring along the north-western and western edge of what is classically known as the Witwatersrand Basin have been hydrothermally altered in two different styles. Both styles - pervasive and vein-controlled alteration - are characterised by sulphide mineralisation as well as by thorium-, uranium-, gold- and REE-rich nodules of carbonaceous material (fly-speck carbon). All of the granitoids

  8. Portal vein aneurysm in a dog.

    PubMed

    Miyawaki, Shingo; Washizu, Makoto; Maeda, Sadatoshi; Shibata, Sanae; Watanabe, Kazuhiro; Yamazoe, Kazuaki

    2012-09-01

    Portal vein aneurysm (PVA) is a rare abnormal dilatation of the portal vein, which has not been reported in dogs. We describe the findings of ultrasound and computed tomography in a case of PVA in a young male toy poodle, with the final diagnosis established by explorative surgical observation. The dog had an aneurysmal fusiform dilatation in the extrahepatic portal vein with portal hypertension and multiple portsystemic shunts. This is the first report of canine PVA. PMID:22571895

  9. MR Venography for the Assessment of Deep Vein Thrombosis in Lower Extremities with Varicose Veins

    PubMed Central

    Nakahara, Hideki

    2014-01-01

    Objective: To assess the performance of magnetic resonance venography (MRV) for pelvis and deep vein thrombosis in the lower extremities before surgical interventions for varicose veins. Materials and Methods: We enrolled 72 patients who underwent MRV and ultrasonography before stripping for varicose veins of lower extremities. All images of the deep venous systems were evaluated by time-of-flight MRV. Results: Forty-six patients (63.9%) of all were female. Mean age was 65.2 ± 10.2 years (37–81 years). There were forty patients (55.6%) with varicose veins in both legs. Two deep vein thrombosis (2.8%) and three iliac vein thrombosis (4.2%) were diagnosed. All patients without deep vein thrombosis underwent the stripping of saphenous veins, and post-thrombotic change was avoided in all cases. Conclusion: MRV, without contrast medium, is considered clinically useful for the lower extremity venous system. PMID:25593625

  10. Deformation mechanics of quartz at a single asperity under hydrothermal conditions

    E-print Network

    Bakku, Sudhish Kumar

    2010-01-01

    Pressure solution is a naturally occurring deformation process in fluid-bearing rocks, with implications for sediment consolidation rates and deformation in the mid to upper crust. The process involves dissolution at ...

  11. Remodelling of the Superior Caval Vein After Angioplasty in an Infant with Superior Caval Vein Syndrome

    SciTech Connect

    Mert, Murat [Istanbul University, Institute of Cardiology, Department of Cardiovascular Surgery (Turkey)], E-mail: mmert@superonline.com; Saltik, Levent [Istanbul University, Cerrahpasa Medical School, Department of Pediatric Cardiology (Turkey); Gunay, Ilhan [Istanbul University, Institute of Cardiology, Department of Cardiovascular Surgery (Turkey)

    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.

  12. 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.

  13. Hydrothermal synthesis of ammonium illite

    USGS Publications Warehouse

    Sucha, V.; Elsass, F.; Eberl, D.D.; Kuchta, L'.; Madejova, J.; Gates, W.P.; Komadel, P.

    1998-01-01

    Synthetic gel and glass of illitic composition, natural kaolinite, and mixed-layer illite-smectite were used as starting materials for hydrothermal synthesis of ammonium illite. Ammonium illite was prepared from synthetic gel by hydrothermal treatment at 300??C. The onset of crystallization began within 3 h, and well-crystallized ammonium illite appeared at 24 h. Increasing reaction time (up to four weeks) led to many illite layers per crystal. In the presence of equivalent proportions of potassium and ammonium, the gel was transformed to illite with equimolar contents of K and NH4. In contrast, synthesis using glass under the same conditions resulted in a mixture of mixed-layer ammonium illite-smectite with large expandability and discrete illite. Hydrothermal treatments of the fine fractions of natural kaolinite and illite-smectite produced ammonium illite from kaolinite but the illite-smectite remained unchanged.

  14. 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 represents a zone of multiple fragmentation, fluid flow, crystallization and quartz dissolution and precipitation, and is regarded as key example of large-scale cyclic interaction of these processes. The geological evidence of interactions between processes implies that feedbacks and highly non-linear mechanical behaviour generated the complex meso- and microstructures. The fault zone rheology may also therefore have been complex.

  15. Distinguishing the Asian dust sources based on cathodoluminescence analysis of single quartz grain

    NASA Astrophysics Data System (ADS)

    Nagashima, K.; Nishido, H.; Kayama, M.; Tada, R.; Isozaki, Y.; Sun, Y.; Igarashi, Y.

    2009-12-01

    Numerous tracers, such as mineralogical component, strontium (87Sr/86Sr) and neodymium (eNd(0)) isotopes (Liu et al., 1994; Biscaye et al.,1997; Bory et al., 2002, 2003; Kanayama et al., 2002, 2005), rare earth element composition (e.g., Svensson et al., 2000), oxygen isotope (Mizota et al., 1992; Hou et al., 2003) and ESR intensity of quartz (Ono et al., 1998; Sun et al., 2007), have been investigated to discriminate source areas of Asian dust. However, these analyses need large volume of samples (mostly more than 10 mg) and the applications to the dust samples are limited. Then, here we developed a provenance-tracing method by using a cathodoluminescence (CL) spectral of “single” quartz grain for applying it to small volume of aeolian dust samples, such as aeolian dust in the ice cores and marine sediments with the location of long distance from the Asian deserts. CL is the emission from a material which is excited by electron beam. Since CL spectroscopy and microscopy provide information on the existence and distribution of defects and trace elements in minerals, CL analyses have potential to characterize dust-source areas. CL spectra of quartz have been demonstrated to show different patterns between the quartz from hydrothermal, plutonic, volcanic and metamorphic origins (e.g., Zinkernagel, 1978; Götze et al., 2001), suggesting the spectra reflect the condition of the quartz formation and the local environment. Then, here we conducted CL spectral analysis of silt size quartz in the surface samples from the major Asian deserts, such as the Taklimakan Desert and Gobi Desert in southern Mongolia (hereafter Mongolian Gobi). CL spectra were measured in the areas of approximately 4 micron square for each quartz grain by a Scanning Electron Microscope-Cathodoluminescence (SEM-CL) at the Okayama University of Science, a SEM (Jeol: JSM-5410) attached with a grating monochromator (Oxford Instruments: Mono CL2), where EDS system can be used in combination with SEM-CL. The CL signals were collected by photon counting method using a PMT (Hamamatsu R2228) in the range from 300 to 800 nm. Most of the silt size quartz in the samples from the Taklimakan Desert and the Mongolian Gobi exhibit double peaks in blue region at around 450 nm (2.75 eV) and red region at around 620 nm (2.00 eV). The wavelengths (energy) of the red peak show slight but significant differences between the samples from the two deserts, although CL intensities of the two peaks show no distinct differences. This result implies that the red peaks of CL spectra of the quartz samples from the two deserts originate from different defects of quartz, and the characteristics of the red peaks have potential to distinguish the source areas of Asian dust.

  16. A tectonic model for the spatial occurrence of porphyry copper and polymetallic vein deposits - applications to Central Europe

    USGS Publications Warehouse

    Drew, Lawrence J.

    2006-01-01

    A structural-tectonic model, which was developed to assess the occurrence of undiscovered porphyry copper deposits and associated polymetallic vein systems for the Matra Mountains, Hungary, has been expanded here and applied to other parts of central Europe. The model explains how granitoid stocks are emplaced and hydrothermal fluids flow within local strain features (duplexes) within strike-slip fault systems that develop in continental crust above subducting plates. Areas of extension that lack shear at the corners and along the edges of the fault duplexes are structural traps for the granitoid stocks associated with porphyry copper deposits. By contrast, polymetallic vein deposits are emplaced where shear and extension are prevalent in the interior of the duplexes. This model was applied to the Late Cretaceous-age porphyry copper and polymetallic vein deposits in the Banat-Timok-Srednogorie region of Romania-Serbia-Bulgaria and the middle Miocene-age deposits in Romania and Slovakia. In the first area, porphyry copper deposits are most commonly located at the corners, and occasionally along the edges, of strike-slip fault duplexes, and the few polymetallic vein deposits identified are located at interior sites of the duplexes. In the second area, the model accounts for the preferred sites of porphyry copper and polymetallic vein deposits in the Apuseni Mountains (Romania) and central Slovakian volcanic field (Slovakia).

  17. Improving the management of varicose veins.

    PubMed

    Onida, Sarah; Lane, Tristan R A; Davies, Alun H

    2013-01-01

    Up to 30% of the UK population are affected by varicose veins. They are a manifestation of increased venous pressure in the lower limb caused by impaired venous return. Primary varicosities result from poor drainage from the superficial to the deep venous system. Secondary varicosities arise as a result of underlying pathology impeding venous drainage, such as deep venous thrombosis or increased intra-abdominal pressure caused by a mass, pregnancy or obesity. Patients with bleeding varicose veins should be referred to a vascular service immediately. Referral is also indicated in the following cases: symptomatic primary or recurrent varicose veins; lower limb skin changes thought to be caused by chronic venous insufficiency; superficial vein thrombosis and suspected venous incompetence; a venous leg ulcer or healed venous leg ulcer. Imaging is crucial in the assessment of the superficial and deep venous system to enable assessment of venous competence. The gold standard imaging technique is colour duplex ultrasonography. Duplex ultrasound should be used to confirm the diagnosis of varicose veins and the extent of truncal reflux, and to plan treatment for patients with suspected primary or recurrent varicose veins. Superficial vein ligation, phlebectomy and stripping have been the mainstay of treatment. In recent years, new techniques have been developed that are minimally invasive, enabling treatment of superficial venous incompetence with reduced morbidity. NICE recommends that endothermal ablation, in the form of radiofrequency or laser treatment, should be offered as treatment for patients with confirmed varicose veins and truncal reflux. PMID:24555256

  18. Fatal lower extremity varicose vein rupture

    Microsoft Academic Search

    Garyfalia Ampanozi; Ulrich Preiss; Gary M. Hatch; Wolf Dieter Zech; Thomas Ketterer; Stephan Bolliger; Michael J. Thali; Thomas D. Ruder

    2011-01-01

    Varicose vein rupture is a rare cause of death, although varicosities are a common pathology. We present three cases of sudden death due to varicose vein rupture. After a review of the literature, the case circumstances and the findings of imaging examination, performed in two cases, are presented. One of them had undergone a post-mortem computed tomography angiography (PMCTA), and

  19. 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...

  20. Arteries and veins of the zebra fish

    NSDL National Science Digital Library

    Katie Hale (CSUF; Biological Sciences)

    2007-06-19

    Arteries and veins are blood vessels and are part of the circulatory system. Arteries take oxygenated blood away from the heart and veins bring blood back to the heart after it has circulated through the body. The circulatory system distributes oxygen to the body and also moves around nutrients.

  1. ESR dating of submarine hydrothermal activities using barite in sulfide deposition

    NASA Astrophysics Data System (ADS)

    Toyoda, S.; Fujiwara, T.; Ishibashi, J.; Isono, Y.; Uchida, A.; Takamasa, A.; Nakai, S.

    2012-12-01

    The temporal change of submarine hydrothermal activities has been an important issue in the aspect of the evolution of hydrothermal systems which is related with ore formation (Urabe, 1995) and biological systems sustained by the chemical species arising from hydrothermal activities (Macdonald et al., 1980). Determining the ages of the hydrothermal deposit will provide essential information on such studies. Dating methods using disequilibrium between radioisotopes such as U-Th method (e.g. You and Bickle, 1998), 226}Ra-{210Pb and 228}Ra-{228Th method (e.g. Noguchi et al., 2011) have been applied to date submarine hydrothermal deposits. ESR (electron spin resonance) dating method is commonly applied to fossil teeth, shells, and quartz of Quaternay period where the natural accumulated dose is obtained from the intensities of the ESR signals which are created by natural radiation. The natural dose is divided by the dose rate to the mineral/sample to deduce the age. Okumura et al., (2010) made the first practical application of ESR (electron spin resonance) dating technique to a sample of submarine hydrothermal barite (BaSO4) to obtain preliminary ages, where Kasuya et al. (1991) first pointed out that barite can be used for ESR dating. Knowing that ESR dating of barite is promising, in this paper, we will present how we have investigated each factor that contributes ESR dating of barite in submarine hydrothermal sulfide deposition. (1) The best ESR condition for measuring the SO3- signal in barite is with the microwave power of 1mW and modulation amplitude of 0.1mT. (2) As results of heating experiments, the signal was found to be stable for the dating age range of several thousands. (3) 226Ra replacing Ba in barite is the source of the radiation. The amount of radioactive elements in sulfide mineral surrounding barite is negligible. (4) The external radiation from the sea water is negligible even in the submarine hydrothermal area where the radiation level is much higher than usual sea water. (5) The decay of 226Ra has to be considered. (6) Major terms of dose rate are the internal alpha dose rate and the external beta and gamma dose rates. (7) The alpha effectiveness, the ratio of forming the radical by internal alpha particles to by beta and gamma rays, was obtained to be 0.043±0.018. (8) The shape of the chimney sample should be considered for gamma ray dose. Examples of dating results for submarine hydrothermal deposits from South Mariana and Okinawa Trough will be presented.

  2. The Quartz Hazard in the Construction Industry

    Microsoft Academic Search

    Paul J. A. Borm; Ken Donaldson

    1999-01-01

    An IARC Working Group has classified crystalline silica (quartz) as a group 1 carcinogen. This classification was mainly based on the epidemiological evidence published in the last decade, including positive studies on workers in the construction industry. The conclusions of the working party were not unanimous with disagreement based on several issues and a qualification was added to the classification.

  3. Extensions of quartz-enhanced photoacoustic spectroscopy

    E-print Network

    Masurkar, Amrita V

    2009-01-01

    The goal of this thesis was to perform quartz-enhanced photoacoustic spectroscopy (QEPAS) on trace concentrations of NH3 in the 1.53 pm region with a DFB laser without the use of a resonating cavity. I analyzed the process ...

  4. Hydrothermal alteration facies within the intrusive-hosted Salave gold prospect, NW Spain

    SciTech Connect

    Harris, M.

    1985-01-01

    The Salave gold prospect occurs within an Hercynian granodioritic complex intruding Cambro-Ordovician metasediments and a heterogeneous gabbroic body. Mineralization consists mostly of disseminated and veinlet pyrite, arsenopyrite, molybdenite, stibnite, and lesser sphalerite associated with a zoned sequence of hydrothermal alteration. Gold occurs as free particles and/or intergrown with the sulfides. Mathematical appraisal of analytical data suggests that the hydrothermal alteration resulted from largely isochemical redistribution processes imposed on the mineralogy of the host granodiorite by influxes of sporadically boiling fluids rich in CO/sub 2/. Hydrothermal alteration is described in terms of a zonal sequence inward from unaltered host rock through (1) chlorite-sericite alteration-(2) propylitic to advanced propylitic alterations-(3)albitites-(4) an auriferous (greater than or equal to 1g/t Au) sericite-carbonate-albite-(+/-)quartz-sulfide cataclastic facies. The zonation corresponds to increasing carbonatization, sericitization, albitization, desilification, and destruction of the original igneous texture. Aventurine alteration is common and is thought to be the product of late stage hydrothermal oxidizing conditions. Potassic alteration in the form of K-feldspar or biotite was occasionally observed.

  5. 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.

  6. Hydrothermal synthesis of perovskite nanotubes.

    PubMed

    Mao, Yuanbing; Banerjee, Sarbajit; Wong, Stanislaus S

    2003-02-01

    A low-temperature hydrothermal reaction has been utilized to generate crystalline barium titanate and strontium titanate nanotubes, which have been characterized by means of X-ray diffraction and transmission electron microscopy, coupled with energy dispersive X-ray analysis. PMID:12613636

  7. Application of Quartz Microresonators to Uncooled Infrared Imaging Arrays

    Microsoft Academic Search

    John R. Vig; Raymond L. Filler; Yoonkee Kim

    1997-01-01

    Introduction Quartz Microresponators as Infrared Sensors Quartz Thermometers and Their Temperature Coefficients Oscillator Noise Frequency Measurement Thermal Isolation Infrared Absorption of Microresonators Predicted performance of Microresonator Arrays Producibility and Other Challenges Summary and Conclusions Appendix. Performance Calculations References

  8. MAPping Out Arteries and Veins

    NSDL National Science Digital Library

    Ryan E. Lamont (Canada; University of Calgary, Calgary AB REV)

    2006-10-03

    Growing evidence suggests that a genetic program specifies the identity of arteries and veins before the onset of circulation. A signaling cascade involving sonic hedgehog (Shh), vascular endothelial growth factor (VEGF), the VEGF receptor 2 (VEGFR2), homeobox proteins Foxc1 and Foxc2, the Notch receptor, and the downstream transcription factor gridlock is required for expression of arterial markers, whereas only a single transcription factor, COUP-TFII (chicken ovalbumin upstream promoter–transcription factor II), has previously been implicated in maintaining venous fate. Recent work has now implicated two competing pathways downstream of VEGFR2 in arterial versus venous specification: Activation of the phospholipase C–? (PLC-?)–mitogen-activated protein kinase (MAPK) pathway acts in arterial specification, whereas the phosphoinositide 3-kinase (PI3K)–Akt pathway acts to allow a venous fate by inhibition of the PLC-?–MAPK pathway. Here, we review this work and discuss how activation of the MAPK signaling cascade could stimulate an arterial fate.

  9. Hydrothermal synthesis of amino acids

    SciTech Connect

    Marshall, W.L. (Oak Ridge National Lab., TN (United States))

    1994-05-01

    This study presents further evidence that amino acids can be synthesized rapidly in hydrothermal solutions from reactants that may have been present in primitive environments. Aqueous NH[sub 4]HCO[sub 3] solutions were reacted with C[sub 2]H[sub 2], H[sub 2], and O[sub 2] (formed in situ from CaC[sub 2], Ca, and H[sub 2]O[sub 2]) at 200-275[degrees]C over 0.2-2 h periods to synthesize several amino acids and abundant amines. These amino acid and amine producing reactions were not observed to occur below 150[degrees]C. Amino acids and amines also were synthesized at 210[degrees]C from solutions of NH[sub 4]OH, HCHO, NaCN, and H[sub 2]. When NH[sub 4]OH was replaced by NH[sub 4]HCO[sub 3], the syntheses predominantly confirmed the recent results of Hennet et al. (1992). Additionally, amino acids and amines were observed to form by reactions among NH[sub 4]OH, HCHO, and H[sub 2] at hydrothermal conditions, essentially confirming the results of Fox and Windsor (1970). Inclusion of both carbonate and O[sub 2] in these latter solutions greatly enhanced the production rate of amino acids. The amines synthesized hydrothermally could be significant if they are precursors in the amino acid syntheses either at hydrothermal or later at lower temperatures. These observations provide additional input to the current questions of synthesis, stability, and decomposition of amino acids at hydrothermal conditions, and their possible relevance to the origin of life.

  10. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, Bhushan L. (Denver, CO)

    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.

  11. Uncooled IR imaging array based on quartz microresonators

    Microsoft Academic Search

    John R. Vig; Raymond L. Filler; Yoonkee Kim

    1996-01-01

    A quartz crystal resonator's resonance frequency is sensitive to temperature. This sensitivity has been exploited in the past in thermometers made of single, macroscopic quartz resonators that can accurately detect temperature changes of ?K. Using semiconductor microfabrication techniques, it is now possible to fabricate a large number of microresonators from a single quartz wafer. It is shown that combining the

  12. Experimental calibration of oxygen isotope fractionation between quartz and zircon

    E-print Network

    Bindeman, Ilya N.

    Experimental calibration of oxygen isotope fractionation between quartz and zircon Dustin Trail a the results of an experimental calibration of oxygen isotope fractionation between quartz and zircon. Data between quartz and zircon can be described by: 1000 ln aqtz­zrc ¼ ð2:33 Æ 0:24Þ Â 106 =T2 ðin KÞ

  13. Impact-induced hydrothermal activity within the Haughton impact structure, arctic Canada: generation of a transient, warm, wet oasis

    NASA Astrophysics Data System (ADS)

    Osinski, Gordon R.; Spray, John G.

    2001-05-01

    Field studies and analytical scanning electron microscopy indicate that a hydrothermal system was created by the interaction of water with hot, impact-generated rocks following formation of the 24 km-diameter, 23 Ma Haughton impact structure. Hydrothermal alteration is recognized in two settings: within polymict impact breccias overlying the central portion of the structure, and within localized pipes in impact-generated concentric fault systems. The intra-breccia alteration comprises three varieties of cavity and fracture filling: (a) sulfide with carbonate, (b) sulfate, and (c) carbonate. These are accompanied by subordinate celestite, barite, fluorite, quartz and marcasite. Selenite is also developed, particularly in the lower levels of the impact breccia sheet. The fault-related hydrothermal alteration occurs in 1-7 m diameter subvertical pipes that are exposed for lengths of up 20 m. The pipes are defined by a monomict quartz-carbonate breccia showing pronounced Fe-hydroxide alteration. Associated sulfides include marcasite, pyrite and chalcopyrite. We propose three distinct stages in the evolution of the hydrothermal system: (1) Early Stage (>200 degC), with the precipitation of quartz (vapour phase dominated); (2) Main Stage (200-100 deg C), with the development of a two phase (vapour plus liquid) zone, leading to calcite, celestite, barite, marcasite and fluorite precipitation, and (3) Late Stage (<100 degC), with selenite and fibroferrite development through liquid phase-dominanted precipitation. We estimate that it took several tens of thousands of years to cool below 50 deg C following impact. During this time, Haughton supported a 14 km diameter crater lake and subsurface water system, providing a warmer, wetter niche relative to the surrounding terrain. The results also reveal how understanding the internal structure of impact craters is necessary in order to determine their plumbing and cooling systems.

  14. A cervelleite-like mineral and other Ag-Cu-Te-S minerals [Ag 2 CuTeS and (Ag,Cu) 2 TeS] in gold-bearing veins in metamorphic rocks of the Cycladic Blueschist Unit, Kallianou, Evia Island, Greece

    Microsoft Academic Search

    Panagiotis Christos Voudouris; Paul G. Spry; Gregory Aarne Sakellaris; Constantinos Mavrogonatos

    2011-01-01

    A cervelleite-like mineral, two unnamed silver sulfotellurides in the system Ag-Cu-Te-S [Ag2CuTeS, (Ag,Cu)2TeS], Te-rich polybasite and cadmian tetrahedrite occur in gold-bearing quartz veins in metapelites and faults within brecciated\\u000a marbles of the Cycladic Blueschist Unit in the Kallianou area (southern Evia Island, Greece). The quartz veins and faults\\u000a are discordant to syn-metamorphic structures and formed during ductile to brittle deformation

  15. Distribution, microfabric, and geochemical characteristics of siliceous rocks in central orogenic belt, China: implications for a hydrothermal sedimentation model.

    PubMed

    Li, Hongzhong; Zhai, Mingguo; Zhang, Lianchang; Gao, Le; Yang, Zhijun; Zhou, Yongzhang; He, Junguo; Liang, Jin; Zhou, Liuyu; Voudouris, Panagiotis Ch

    2014-01-01

    Marine siliceous rocks are widely distributed in the central orogenic belt (COB) of China and have a close connection to the geological evolution and metallogenesis. They display periodic distributions from Mesoproterozoic to Jurassic with positive peaks in the Mesoproterozoic, Cambrian--Ordovician, and Carboniferous--Permian and their deposition is enhanced by the tensional geological settings. The compressional regimes during the Jinning, Caledonian, Hercynian, Indosinian, and Yanshanian orogenies resulted in sudden descent in their distribution. The siliceous rocks of the Bafangshan-Erlihe ore deposit include authigenic quartz, syn-depositional metal sulphides, and scattered carbonate minerals. Their SiO2 content (71.08-95.30%), Ba (42.45-503.0 ppm), and ?REE (3.28-19.75 ppm) suggest a hydrothermal sedimentation origin. As evidenced by the Al/(Al + Fe + Mn), Sc/Th, (La/Yb) N, and (La/Ce) N ratios and ?Ce values, the studied siliceous rocks were deposited in a marginal sea basin of a limited ocean. We suggest that the Bafangshan-Erlihe area experienced high- and low-temperature stages of hydrothermal activities. The hydrothermal sediments of the former stage include metal sulphides and silica, while the latter was mainly composed of silica. Despite the hydrothermal sedimentation of the siliceous rocks, minor terrigenous input, magmatism, and biological activity partly contributed to geochemical features deviating from the typical hydrothermal characteristics. PMID:25140349

  16. Chemical equilibrium and mass balance relationships associated with the Long Valley hydrothermal system, California, U.S.A.

    USGS Publications Warehouse

    White, A.F.; Peterson, M.L.

    1991-01-01

    Recent drilling and sampling of hydrothermal fluids from Long Valley permit an accurate characterization of chemical concentrations and equilibrium conditions in the hydrothermal reservoir. Hydrothermal fluids are thermodynamically saturated with secondary quartz, calcite, and pyrite but are in disequilibrium with respect to aqueous sulfide-sulfate speciation. Hydrothermal fluids are enriched in 18O by approximately 1??? relative to recharge waters. 18O and Cl concentrations in well cuttings and core from high-temperature zones of the reservoir are extensively depleted relative to fresh rhyolitic tuff compositions. Approximately 80% of the Li and 50% of the B are retained in the altered reservoir rock. Cl mass balance and open-system 18O fractionation models produce similar water-rock ratios of between 1.0 and 2.5 kg kg-1. These water-rock ratios coupled with estimates of reservoir porosity and density produce a minimum fluid residence time of 1.3 ka. The low fluid Cl concentrations in Long Valley correlate with corresponding low rock concentrations. Mass balance calculations indicate that leaching of these reservoir rocks accounts for Cl losses during hydrothermal activity over the last 40 ka. ?? 1991.

  17. Distribution, Microfabric, and Geochemical Characteristics of Siliceous Rocks in Central Orogenic Belt, China: Implications for a Hydrothermal Sedimentation Model

    PubMed Central

    Li, Hongzhong; Zhai, Mingguo; Zhang, Lianchang; Gao, Le; Yang, Zhijun; Zhou, Yongzhang; He, Junguo; Liang, Jin; Zhou, Liuyu; Voudouris, Panagiotis Ch.

    2014-01-01

    Marine siliceous rocks are widely distributed in the central orogenic belt (COB) of China and have a close connection to the geological evolution and metallogenesis. They display periodic distributions from Mesoproterozoic to Jurassic with positive peaks in the Mesoproterozoic, Cambrian—Ordovician, and Carboniferous—Permian and their deposition is enhanced by the tensional geological settings. The compressional regimes during the Jinning, Caledonian, Hercynian, Indosinian, and Yanshanian orogenies resulted in sudden descent in their distribution. The siliceous rocks of the Bafangshan-Erlihe ore deposit include authigenic quartz, syn-depositional metal sulphides, and scattered carbonate minerals. Their SiO2 content (71.08–95.30%), Ba (42.45–503.0?ppm), and ?REE (3.28–19.75?ppm) suggest a hydrothermal sedimentation origin. As evidenced by the Al/(Al + Fe + Mn), Sc/Th, (La/Yb)N, and (La/Ce)N ratios and ?Ce values, the studied siliceous rocks were deposited in a marginal sea basin of a limited ocean. We suggest that the Bafangshan-Erlihe area experienced high- and low-temperature stages of hydrothermal activities. The hydrothermal sediments of the former stage include metal sulphides and silica, while the latter was mainly composed of silica. Despite the hydrothermal sedimentation of the siliceous rocks, minor terrigenous input, magmatism, and biological activity partly contributed to geochemical features deviating from the typical hydrothermal characteristics. PMID:25140349

  18. Brain vein disorders in newborn infants.

    PubMed

    Raets, Marlou; Dudink, Jeroen; Raybaud, Charles; Ramenghi, Luca; Lequin, Maarten; Govaert, Paul

    2015-03-01

    The brain veins of infants are in a complex phase of remodelling in the perinatal period. Magnetic resonance venography and susceptibility-weighted imaging, together with high-resolution Doppler ultrasound, have provided new tools to aid study of venous developmental anatomy and disease. This review aims to provide a comprehensive background of vein development and perinatal venous lesions in preterm and term-born infants, and to encourage further research in both the fetus and the newborn infant, with the aim of preventing or mitigating parenchymal injury related to diseases involving veins. PMID:25212961

  19. Water transport during metamorphic vein formation: the role of reaction-induced pressure buildup during serpentinization

    NASA Astrophysics Data System (ADS)

    Malvoisin, Benjamin; Podladchikov, Yuri

    2014-05-01

    At slow-spreading ridges, the extension is accommodated both by an exhumation of mantle rocks and a magmatic input. The heat released during the crystallization of the magmas is evacuated through the hydrothermal circulation transporting high-temperature fluids up to mantle rocks which can be hydrated through a serpentinization reaction. At the millimetre scale, water transport is also accommodated by advection in the highly permeable fracture network typically found in serpentinized peridotites. This high permeability is the consequence of fracturing processes related to lithospheric scale deformation, thermal contraction or a pressure build-up associated with the positive volume increase occurring during the reaction. If the relationship between pressure increase and fracturing has been studied in details, the impact of this pressure increases on the fluid flow is still unclear. Therefore, we used existing data on the texture and composition of serpentine veins (mm to µm scale) found in peridotites to identify the physical processes involved in the transport of water during the reaction. A finite difference model was then developed to investigate the couplings between pressure increase and fluid flow at the scale of the vein. This model will allow us to probe the influence on the reaction of parameters such as the kinetics of the reaction, the geometry and the texture of the veins, the amount of the volume increase, or the external forces.

  20. ATS-6 - Quartz-Crystal Microbalance

    NASA Technical Reports Server (NTRS)

    Rogers, J. F.

    1975-01-01

    The Quartz-Crystal Microbalance Experiment provided data on the possible return of contaminants to the exterior surfaces of the spacecraft. The experiment measures the change in resonant frequency of the crystal due to deposition of material on the surface. There has been no mass accretion corresponding to the firing of hydrazine thrusters to unload the spacecraft momentum wheels. There have been accretions corresponding to the firing of the cesium ion engines.

  1. Specific features of quartz crystals lamellar structure

    Microsoft Academic Search

    N. M. Bauer; A. P. Pogrebnyak; S. N. Abdrafikov; N. A. Mamaev; B. V. Shulgin

    1995-01-01

    This report gives results of experimental investigations of the structural Al distribution in quartz crystals grown on seeds making desired angles with the face {101¯0} (nonsingular faces (NF) of the zone [0001]). It has previously been shown that regeneration growth pyramids of these crystals possess a stepped growth surface formed by faces {1¯120} and {101¯0}. Moreover, certain relationships between the

  2. Boron isotope systematics of hydrothermal fluids from submarine hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Yamaoka, K.; Hong, E.; Ishikawa, T.; Gamo, T.; Kawahata, H.

    2013-12-01

    Boron is highly mobile in submarine hydrothermal systems and useful to trace the process of water-rock reaction. In this study, we measured the boron content and isotopic composition of vent fluids collected from arc-backarc hydrothermal systems in the western Pacific. In sediment-starved hydrothermal systems (Manus Basin, Suiyo Seamount, and Mariana Trough), the boron content and isotopic composition of vent fluids are dependent on type of host rock. The end member fluids from MORB-like basalt-hosted Vienna Woods in the Manus Basin showed low boron content and high ?11B value (0.53 mM, 29.8‰), while dacite-hosted PACMANUS and the Suiyo Seamount showed high boron contents and low ?11B values (1.45 and 1.52 mM, 13.6 and 18.5‰, respectively). The Alice Springs and Forecast Vent field in the Mariana Trough showed values intermediate between them (0.72 and 0.63 mM, 19.9 and 24.0‰, respectively), reflecting reaction of seawater and basalt influenced by slab material. In phase separated hydrothermal systems (North Fiji Basin), boron content and isotopic composition of vent fluids (0.44-0.56 mM, 34.5-35.9‰) were similar to those in the Vienna Woods. Considering little fractionation of boron and boron isotope during phase separation demonstrated by the previous experimental studies, it is suggested that the host rock in the North Fiji Basin is MORB-like basalt. In sediment-hosted hydrothermal system (Okinawa Trough), the reaction with boron-enriched sediment following seawater-rock reaction resulted in significantly high boron contents and low ?11B values of vent fluids (4.4-5.9 mM, 1.5-2.6‰). The water-sediment ratio was estimated to be ~2. In spite of the different geological settings, the end member fuids from all vent fields are enriched in B relative to seawater (0.41 mM, 39.6‰) and the ?11B values are inversely propotional to the boron concentrations. It suggests that boron isotopic composition of vent fluid predominantly depends on the amount of boron originated from solid-phase.

  3. Fracture and vein characterization of a crystalline basement reservoir, central Yemen

    NASA Astrophysics Data System (ADS)

    Veeningen, R.; Grasemann, B.; Decker, K.; Bischoff, R.; Rice, A. H. N.

    2012-04-01

    The country of Yemen is located in the south-western part of the Arabian plate. The Pan-African basement found in western and central Yemen is highly deformed during the Proterozoic eon and is part of the Arabian-Nubian shield ANS (670-540Ma). This ANS is a result of the amalgamation of high-grade gneiss terranes and low-grade island arcs. The development of an extensive horst-and-graben system related to the breakup of Gondwana in the Mesozoic, has reactivated the Pan-African basement along NW-SE trending normal faults. As a result, younger Meosozoic marls, sandstones, clastics and limestones are unconformably overlying the basement. Some of these formations act as a source and/or reservoir for hydrocarbons. Due to fracturing of the basement, hydrocarbons have migrated horizontally into the basement, causing the crystalline basement to be a potential hydrocarbon reservoir. Unfortunately, little is known about the Pan-African basement in Central Yemen and due its potential as a reservoir, the deformation and oil migration history (with a main focus on the fracturing and veining history) of the basement is investigated in high detail. Representative samples are taken from 2 different wells from the Habban Field reservoir, located approximately 320 ESE of Sana'a. These samples are analysed using e.g. the Optical Microscope, SEM, EDX and CL, but also by doing Rb-Sr age dating, isotope analysis and fluid inclusion analysis. In well 1, the only lithology present is an altered gneiss with relative large (<5 cm diameter) multi-mineralic veins. In well 3, quartzite (top), gneiss (middle) and quartz porphyry's (middle) are intruded by a so called "younger" granitoid body (592.6±4.1Ma). All lithologies record polyphase systems of mineral veins. Pyrite and saddle dolomite in these veins have euhedral shapes, which means that they have grown in open cavities. Calcite is the youngest mineral in these veins, closing the vein and aborting the fluid flow. Fluid inclusions inside the calcite record homogenization temperatures (Th) of approximately 120°C with a maximum of 140°C. This is thought to be approximately equal to the calcite formation temperature. Also the euhedral saddle dolomite is thought to be formed at approximately these temperatures. Migration and precipitation of the vein systems represents an important process in the formation of the crystalline basement hydrocarbon reservoir.

  4. An Experimental Study of Lithium Isotope Partitioning Among Quartz, Muscovite, and Fluid

    NASA Astrophysics Data System (ADS)

    Lynton, S. J.; Walker, R. J.; Candela, P. A.

    2002-05-01

    Preliminary results from an experimental study suggest that lithium isotopes may serve as an indicator of magmatic hydrothermal processes in felsic environments, such as granitic pegmatites and porphyry-type ore deposits. The experiments were carried out with natural (pegmatitic) specimens of quartz and muscovite and with a chloride-bearing aqueous fluid at 400-500° C and 50-100 MPa. Lithium was introduced into the experimental charges through the fluid, which also contains KCl and HCl (K/Li/H = 100/10/1) and is 1M in total chloride. Two other phases (K-feldspar and phlogopite) were included in the charges to permit coupled substitutions by Li + Al and by Li + Mg into Qz and Ms. In contrast with experiments in other isotope systems (eg., O), Li partitioning experiments require allowance for coupled substitutions because some crystallographic sites only become available to Li through coupled substitutions and because the chemical potentials of components necessary for coupled substitutions must be fixed to define fully the thermodynamic conditions of Li partitioning. In two of the experiments a 6Li spike was used to prepare the fluid to magnify the shifts in Li isotopic compositions among run products. The experiments were conducted for 15-60 days under argon pressure with Pt capsules, which were loaded into Inconel 625 cold seal vessels. The experimental design permits simultaneous determination of isotopic fractionation and elemental partitioning by Li among quartz, muscovite and the fluid. Lithium isotopic compositions were determined by thermal ionization mass spectrometry with a triple-filament technique, in which samples are evaporated from side filaments as a phosphate and Li ions are measured directly by the peak-jumping method. Replicate analyses and duplicate experiments indicate reproduceability within approximately +/-1-2‰ . Li concentrations were determined by isotope dilution. For the 500° C runs, the preliminary results provide some indications that equilibrium was approached, such as lack of variance with run duration or with approach from higher as compared with lower temperature. The preliminary results, particularly those from the spiked runs, suggest that quartz and muscovite are susceptible to appreciable changes in Li isotopic composition within short times through diffusion by interaction with a Li-bearing fluid at 500° C. At that temperature, the quartz run products were enriched in 7Li by approximately 9‰ compared with the fluid run products but were depleted in 7Li by approximately 10‰ compared with the muscovite run products. The results also suggest that the Li isotopic composition of the two minerals is likely influenced by temperature, though not measurably by pressure. The results may provide a way to model the Li isotopic composition of hydrothermal fluids that have interacted with felsic rocks. For example, if the quartz starting specimen used in the experiments were assumed hypothetically to have crystallized in a pegmatite body that interacted with a Li-bearing fluid at 500° C, the Li isotopic composition of the starting specimen (? 7Li = +28) would imply a model ? 7Li value of +19 for the fluid (? Quartz-Fluid = 9).

  5. Sulfur and oxygen isotope insights into sulfur cycling in shallow-sea hydrothermal vents, Milos, Greece

    PubMed Central

    2014-01-01

    Shallow-sea (5 m depth) hydrothermal venting off Milos Island provides an ideal opportunity to target transitions between igneous abiogenic sulfide inputs and biogenic sulfide production during microbial sulfate reduction. Seafloor vent features include large (>1 m2) white patches containing hydrothermal minerals (elemental sulfur and orange/yellow patches of arsenic-sulfides) and cells of sulfur oxidizing and reducing microorganisms. Sulfide-sensitive film deployed in the vent and non-vent sediments captured strong geochemical spatial patterns that varied from advective to diffusive sulfide transport from the subsurface. Despite clear visual evidence for the close association of vent organisms and hydrothermalism, the sulfur and oxygen isotope composition of pore fluids did not permit delineation of a biotic signal separate from an abiotic signal. Hydrogen sulfide (H2S) in the free gas had uniform ?34S values (2.5?±?0.28‰, n?=?4) that were nearly identical to pore water H2S (2.7?±?0.36‰, n?=?21). In pore water sulfate, there were no paired increases in ?34SSO4 and ?18OSO4 as expected of microbial sulfate reduction. Instead, pore water ?34SSO4 values decreased (from approximately 21‰ to 17‰) as temperature increased (up to 97.4°C) across each hydrothermal feature. We interpret the inverse relationship between temperature and ?34SSO4 as a mixing process between oxic seawater and 34S-depleted hydrothermal inputs that are oxidized during seawater entrainment. An isotope mass balance model suggests secondary sulfate from sulfide oxidation provides at least 15% of the bulk sulfate pool. Coincident with this trend in ?34SSO4, the oxygen isotope composition of sulfate tended to be 18O-enriched in low pH (<5), high temperature (>75°C) pore waters. The shift toward high ?18OSO4 is consistent with equilibrium isotope exchange under acidic and high temperature conditions. The source of H2S contained in hydrothermal fluids could not be determined with the present dataset; however, the end-member ?34S value of H2S discharged to the seafloor is consistent with equilibrium isotope exchange with subsurface anhydrite veins at a temperature of ~300°C. Any biological sulfur cycling within these hydrothermal systems is masked by abiotic chemical reactions driven by mixing between low-sulfate, H2S-rich hydrothermal fluids and oxic, sulfate-rich seawater. PMID:25183951

  6. Microstructural evolution of syntaxial veins formed by advective flow

    Microsoft Academic Search

    Christoph Hilgers; Karin Dilg-Gruschinski; Janos L. Urai

    2004-01-01

    Veins are common in Earth's crust, and are formed by a wide range of processes, which lead to crystal growth in dilation sites. The first-order processes in vein formation have been identified, but it is much less clear how these can be diagnosed from field studies. In order to better understand the microstructural evolution during vein growth, we grew veins

  7. Predictive Microbiology in Hydrothermal Ecosystems

    Microsoft Academic Search

    E. L. Shock; M. E. Holland; D. Meyer-Dombard; J. P. Amend

    2004-01-01

    Metabolisms of high-temperature microorganisms are not revealed by molecular phylogenies, but, if known, could connect microbial and geochemical processes in hydrothermal ecosystems. Disequilibria among oxidation-reduction reactions, established by kinetic barriers to electron-transfer reactions, provide energy, and life provides the catalyst. In more-or-less closed systems, such as slowly-accumulating detrital sediments, life taps as much energy as conversion efficiency will allow, and

  8. Hydrothermal synthesis of zirconia nanomaterials

    Microsoft Academic Search

    R. R Piticescu; C Monty; D Taloi; A Motoc; S Axinte

    2001-01-01

    Yttria-stabilised zirconia powders and films have been obtained from Zr(IV) peroxides by hydrothermal crystallisation at temperatures in the range 125–200°C. The thermodynamic evaluation evidenced that formation of Zr(OH)5? in H2O2 solutions increases solubility of Zr (IV) hydrated species and improves the kinetics of the new phase formation by the solubilisation-reprecipitation process. Powders with crystallite sizes in the range 6–22 nm

  9. Deep Vein Thrombosis (DVT) (Beyond the Basics)

    MedlinePLUS

    ... embolism in pregnancy: Treatment Diagnosis of suspected deep vein thrombosis of the lower extremity Etiology, clinical features, and diagnosis of cerebral venous thrombosis Evaluating patients with established venous thromboembolism ...

  10. How Can Deep Vein Thrombosis Be Prevented?

    MedlinePLUS

    ... prevent deep vein thrombosis (DVT) and pulmonary embolism (PE). If you're at risk for these conditions: ... from forming. If you've had DVT or PE before, you can help prevent future blood clots. ...

  11. Hydrothermal synthesis of lithium iron phosphate cathodes

    Microsoft Academic Search

    Shoufeng Yang; Peter Y. Zavalij; M. Stanley Whittingham

    2001-01-01

    Hydrothermal methods have been successfully applied to the synthesis of lithium iron phosphates. Li3Fe2(PO4)3 was synthesized by heating at 700°C LiFePO4(OH), formed hydrothermally in an oxidizing environment. Crystalline LiFePO4 was formed in a direct hydrothermal reaction in just a few hours, and no impurities were detected. This result leads to the possibility of an easy scale-up to a commercial process.

  12. Mystery of the Megaplume: Hydrothermal Vent Chemistry

    NSDL National Science Digital Library

    In this lesson, students will investigate hydrothermal vents to see how the chemistry of the water they emit provides clues to the location of the vents. They should be able to describe hydrothermal vents and characterize vent plumes in terms of physical and chemical properties; describe data gathering operations in which a towed instrument package ("tow-yo") measures conductivity, temperature, and depth; and interpret temperature anomaly data to recognize a plume emanating from a hydrothermal vent.

  13. Temperature record of quartz mylonite during exhumation

    NASA Astrophysics Data System (ADS)

    Grujic, Djordje; Heidelbach, Florian; Mrkwiczka, Sanna; Ullemeyer, Klaus

    2013-04-01

    We present a study in which quartz microstructure, texture, geothermometry (Ti-in-quartz) and conventional thermobarometry are used to constrain the temperature of deformation in a granulite grade shear zone during exhumation and cooling. The samples are from a major crustal detachment in central-south Madagascar. The 1 to 25 km thick Betsileo shear zone separates two contrasting major geological units: (1) the Antananarivo Block in the footwall and (2) in the hanging wall the Southwest Madagascar Block comprising several lithotectonic domains. Due to the complex deformation history of both blocks and of the shear zone there is no consensus on its kinematics and age but the shear zone was most likely playing major role in both crustal thickening and crustal thinning during the Late Neo-Proterozoic to Ordovician. Quartz optical microstructure is characterized by the grain boundary migration recrystallisation as the dominant dynamic deformation mechanism, which together with chessboard extinction suggests peak deformation temperatures in excess of 650 °C. This microstructure is overprinted to different degree by the subgrain rotation recrystallisation. Because of the large grain size any standard crystallographic preferred orientation measurement would show single-grain texture and thus be statistically irrelevant. For this reason we performed texture measurements on a neutron texture goniometer which analyses rock cylinders 28 mm in diameter and 28 mm high. The obtained texture is consistent with high temperature of deformation inferred from the microstructure and thermobarometry. The kinematics of the shear zone is consistent with a dominant flattening rather than a plane-strain simple shear, which may be an additional reason why researchers disagree on the kinematics of the shear zone. The analyses for the Ti-in-quartz thermometry were all done on the SHRIMP RG (Sensitive High Resolution Ion MicroProbe, Reverse Geometry), which allows for a high spatial resolution and high sensitivity of measurements. To link the temperature measurements to the microstructure and texture the samples were imaged by cathodoluminescence and electron backscatter diffraction before and after the SHRIMP measurements respectively. The range of within-sample temperature variation is consistent with the relative degree of the retrograde overprint. However there temperature distribution is more consistent with the CL pattern than with the microstructure and texture. Together with relatively low temperatures (500-550 °C) this suggest that the cooling and related volume diffusion of trace elements (i.e. Ti) in quartz outlasted the deformation.

  14. Primary leiomyosarcoma of the innominate vein.

    PubMed

    Illuminati, Giulio; Miraldi, Fabio; Mazzesi, Giuseppe; D'urso, Antonio; Ceccanei, Gianluca; Bezzi, Marcello

    2007-01-01

    Primary venous leiomyosarcoma is rare. We report the case of a primary leiomyosarcoma of the left innominate vein, with neoplastic thrombus extending into the left jugular and subclavian veins. The tumor was curatively resected en bloc with anterior mediastinal and laterocervical lymphatics, through a median sternotomy prolonged into left cervicotomy. Primary venous sarcomas may be associated with prolonged survival in individual cases, with curative resection recommended as the standard treatment, in the absence of distant spread. PMID:17349340

  15. Portal vein thrombosis in liver cirrhosis

    Microsoft Academic Search

    Filippo Luca Fimognari; Francesco Violi

    2008-01-01

    Portal vein thrombosis (PVT) is observed in 10–20% of patients with liver cirrhosis, which is responsible for 20% of all PVT\\u000a cases. The main pathogenic factor of PVT in cirrhosis is the obstacle to portal flow, but acquired and inherited clotting\\u000a abnormalities may play a role. The formation of collateral veins allows many patients to remain asymptomatic and prevents\\u000a the

  16. The Influence of Calcite on The Mechanical Behavior of Quartz-Bearing Gouge

    NASA Astrophysics Data System (ADS)

    Carpenter, Brett; Di Stefano, Giuseppe; Collettini, Cristiano

    2015-04-01

    Mechanical heterogeneities along faults can result in diverse and complex fault slip. These heterogeneities can vary spatially and temporally and may result from changes in fault structure or frictional properties. The accumulation of calcite in non-carbonate faults, via cementation or entrainment, is likely to alter the frictional properties of that fault gouge. Furthermore, widespread observations of calcite as cement, veins, or cataclasites in non-carbonate hosted faults indicates that calcite is readily available and could play an important role during fault reactivation at shallow- and mid-crustal earthquakes. We report on laboratory experiments designed to explore the mechanical behavior of quartz/calcite mixtures as a means to better understand the evolution in behavior of quartz-bearing gouge in the presence of exotic calcite. We sheared mixtures of powdered Carrara marble (>98% CaCO3) and disaggregated Ottawa sand (99.8% SiO2) at constant normal stresses of 5 and 50 MPa under saturated conditions at room temperature. We performed slide-hold-slide tests, 1-3,000 seconds, and velocity stepping tests, 0.1-1000 µm/s, to measure the amount of frictional healing and velocity dependence of friction respectively. At low normal stress, the addition of calcite to quartz-based synthetic fault gouge results in increases in the steady-state frictional strength, and rates of frictional healing and creep relaxation of the gouge. In particular, with the addition of as little as 2.5 wt% calcite, the frictional healing rate increases by 30%. Microstructural observations indicate that shear is accommodated by distributed deformation throughout the gouge layer and that calcite undergoes significantly more comminution compared to quartz. Large quartz grains frequently show minor rounding of angular edges with fine-grained calcite often penetrating fractures. The in-situ addition of calcite to fault gouge, by either the circulation of fluids or the involvement of carbonate rocks in faulting, could lead to significant and progressive changes in fault behavior, i.e. the fault could be frictionally stronger, heal/seal faster, and be more frictionally unstable. At shallow crustal conditions, increased temperature and the concentration of fine-grained calcite along shear surfaces would result in the amplification of the observed behaviors.

  17. Veins Improve Fracture Toughness of Insect Wings

    PubMed Central

    Dirks, Jan-Henning; Taylor, David

    2012-01-01

    During the lifetime of a flying insect, its wings are subjected to mechanical forces and deformations for millions of cycles. Defects in the micrometre thin membranes or veins may reduce the insect’s flight performance. How do insects prevent crack related material failure in their wings and what role does the characteristic vein pattern play? Fracture toughness is a parameter, which characterises a material’s resistance to crack propagation. Our results show that, compared to other body parts, the hind wing membrane of the migratory locust S. gregaria itself is not exceptionally tough (1.04±0.25 MPa?m). However, the cross veins increase the wing’s toughness by 50% by acting as barriers to crack propagation. Using fracture mechanics, we show that the morphological spacing of most wing veins matches the critical crack length of the material (1132 µm). This finding directly demonstrates how the biomechanical properties and the morphology of locust wings are functionally correlated in locusts, providing a mechanically ‘optimal’ solution with high toughness and low weight. The vein pattern found in insect wings thus might inspire the design of more durable and lightweight artificial ‘venous’ wings for micro-air-vehicles. Using the vein spacing as indicator, our approach might also provide a basis to estimate the wing properties of endangered or extinct insect species. PMID:22927966

  18. Preoperative and intraoperative evaluation of diameter-reflux relationship of calf perforating veins in patients with primary varicose vein

    Microsoft Academic Search

    Naoto Yamamoto; Naoki Unno; Hiroshi Mitsuoka; Takaaki Saito; Keita Miki; Kei Ishimaru; Hiroshi Kaneko; Satoshi Nakamura

    2002-01-01

    Objective: Interruption of incompetent perforating veins (PVs) is important for varicose vein surgery. The purpose of this study was to evaluate the preoperative and intraoperative diameter-reflux relationship of PVs and to evaluate the accuracy of preoperative duplex scanning in patients with varicose vein. Methods: Patients with primary varicose veins were retrospectively investigated. Diameters and reflux of PVs were evaluated before

  19. Gonadal vein tumor thrombosis due to renal cell carcinoma.

    PubMed

    Haghighatkhah, Hamidreza; Karimi, Mohammad Ali; Taheri, Morteza Sanei

    2015-01-01

    Renal cell carcinoma (RCC) had a tendency to extend into the renal vein and inferior vena cava, while extension into the gonadal vein has been rarely reported. Gonadal vein tumor thrombosis appears as an enhancing filling defect within the dilated gonadal vein anterior to the psoas muscle and shows an enhancement pattern identical to that of the original tumor. The possibility of gonadal vein thrombosis should be kept in mind when looking at an imaging study of patients with RCC. PMID:25624585

  20. Gonadal vein tumor thrombosis due to renal cell carcinoma

    PubMed Central

    Haghighatkhah, Hamidreza; Karimi, Mohammad Ali; Taheri, Morteza Sanei

    2015-01-01

    Renal cell carcinoma (RCC) had a tendency to extend into the renal vein and inferior vena cava, while extension into the gonadal vein has been rarely reported. Gonadal vein tumor thrombosis appears as an enhancing filling defect within the dilated gonadal vein anterior to the psoas muscle and shows an enhancement pattern identical to that of the original tumor. The possibility of gonadal vein thrombosis should be kept in mind when looking at an imaging study of patients with RCC PMID:25624585

  1. Exploiting Quartz to Constrain Pressure-Temperature-time-Deformation Histories in Metamorphic Rocks Through Recent Innovations in Thermobarometry and Geospeedometry

    NASA Astrophysics Data System (ADS)

    Ashley, Kyle; Law, Richard; Thomas, Jay; Caddick, Mark; Stahr, Donald, III

    2013-04-01

    Despite the abundance of quartz in continental crust, it has only recently been exploited for thermobarometric purposes. We are using trace element content, cathodoluminescence (CL) characteristics, fabric properties, extent of recrystallization, elastic properties and chemical diffusivities of quartz to better understand the pressure-temperature-time-deformation (P - T - t - D) histories of metamorphic rocks. The Ti-in-quartz thermobarometer has significant potential for unveiling important information on the metamorphic history of rocks, since quartz is commonly present in multiple microstructural settings (e.g. matrix, veins, inclusions) and zoning may be present in single crystals that reveal information about the reequilibration, recrystallization and growth histories of quartz. CL imaging provides a qualitative way to obtain such information, and provides a domainal framework for targeted quantitative analyses. We illustrate such analyses with examples from Vermont, India and Greece. A recent study in metapelites from central-eastern Vermont revealed crystals that have low Ti cores (interpreted to be preserved early prograde growth), with mantles that grade to higher Ti, attributed to temperature increase during fabric development and liberation of Si during crenulation cleavage development in the micaceous matrix. Low-Ti overgrowth rims that form sharp boundaries with these graded mantles may be later retrograde overgrowths. Forward modeling the expected volume of quartz present in the rock in P - T space may be implemented to confirm periods of quartz production/precipitation and dissolution. Rocks from the Sutlej Valley (north-west India) have matrix quartz grains with triple junction grain boundaries indicating extensive recovery. CL imaging, however, reveals high Ti ribbons that may be indicative of chemically-preserved paleo-microstructures. At the temperatures and metamorphic rates experienced by these samples, grain boundaries during recovery may not redistribute impurities, but rather behave passively. A recent advance in implementing Raman spectroscopy on quartz inclusions in porphyroblasts facilitates accurate geobarometry for the time of porphyroblast growth. The method requires that elastic parameters of the host and inclusion are determined, but is independent of the composition of these phases. A recent application of this technique to garnets from blueschists in Sifnos, Greece, resulted in P - T paths for garnet growth from 19.5 kbar at 460 ° C to 21.5 kbar at 550 ° C. These results are in good agreement with recent studies attempting to constrain peak metamorphic histories for these rocks through equilibrium assemblage diagrams and trace element thermobarometry. Preliminary Raman work from the Sutlej Valley samples suggests peak pressures of c. 6.3 kbar approaching the Main Central Thrust. It may be advantageous to couple this geobarometer with Ti-in-quartz on inclusions in garnet to elucidate thermobarometric information relative to microstructural context and deformation history. An additional benefit to this technique is that pressure constraints needed for Ti-in-quartz thermobarometry may now be independently constrained and requires no knowledge of stable mineral assemblages, component activities or mixing parameters. Titanium diffusion from host (garnet) to included quartz may also be implemented to obtain geospeedometry information to estimate the duration of metamorphism. The integration of microstructural analysis with these various techniques may allow for a better understanding of the P - T - t - D histories of rocks than previously obtained using conventional techniques.

  2. Recent population expansion and connectivity in the hydrothermal shrimp

    E-print Network

    Teixeira, Sara

    ORIGINAL ARTICLE Recent population expansion and connectivity in the hydrothermal shrimp Rimicaris of the shrimp Rimicaris exoculata, which forms high-density local populations on hydrothermal vents along

  3. Hydrothermal studies in a new diamond anvil cell up to 10 GPa and from -190°C to 1200°C

    USGS Publications Warehouse

    Bassett, William A.; Shen, A.H.; Bucknum, M.; Chou, I.-Ming

    1993-01-01

    The new hydrothermal diamond anvil cell (HDAC) has been designed for optical microscopy and X-ray diffraction at pressures up to 10 GPa and temperatures between ?190°C and 1200°C. Laser light reffected from the top and bottom anvil faces and the top and bottom solid sample faces produce interference fringes that provide a very sensitive means of monitoring the volume of sample chamber and for observing volume and refractive index changes in solid samples due to transitions and reactions. Synchrotron radiation has been used to make X-ray diffraction patterns of samples under hydrothermal conditions. Individual heaters and individual thermocouples provide temperature control with an accuracy of ±0.5°C. Liquid nitrogen directly introduced into the HDAC has been used to reduce the sample temperature to ?190°C. The ?-? phase boundary of quartz has been used to calculate the transition pressures from measured transition temperatures. With this method we have redetermined 5 isochores of H2O up to 850°C and 1.2 GPa at which the solution rate of the quartz became so rapid that the quartz dissolved completely before the ?-? transition could be observed. When silica solutions were cooled, opal spherules and rods formed.

  4. Controls of fluid chemistry and complexation on rare-earth element contents of anhydrite from the Pacmanus subseafloor hydrothermal system, Manus Basin, Papua New Guinea

    Microsoft Academic Search

    Wolfgang Bach; Stephen Roberts; David A. Vanko; Ray A. Binns; Chris J. Yeats; Paul R. Craddock; Susan E. Humphris

    2003-01-01

    .  \\u000a Ocean Drilling Program (ODP) leg 193 successfully drilled four deep holes (126 to 386 m) into basement underlying the active\\u000a dacite-hosted Pacmanus hydrothermal field in the eastern Manus Basin. Anhydrite is abundant in the drill core material, filling\\u000a veins and vesicles, cementing breccias, and occasionally replacing igneous material. We report rare-earth element (REE) contents\\u000a of anhydrite from a site of

  5. The Iceland Deep Drilling Project (IDDP): (4) A Quartz Fluid Inclusion Tool for Sampling Supercritical Geothermal Fluids Downhole

    NASA Astrophysics Data System (ADS)

    Reed, M. H.; Grist, H.; Fridriksson, T.; Danielsen, P.; Senkovich, D.; Johnston, A.; Elders, W. A.; Fridleifsson, G. O.

    2009-12-01

    Chemical analyses of in situ samples of supercritical geothermal fluids would provide a uniquely good measure of fluid composition at depth relative to compositions reconstructed from analyses of gas and liquid sampled at wellheads. Fluids sampled at the wellhead are commonly a mixture from multiple aquifers and, in many circumstances, they lack components such as sulfate, sulfide, Ca, Cu, Zn, and Fe that precipitated in scale minerals where the fluids boiled or cooled during their ascent. To circumvent the above problems and the failings of downhole mechanical samplers at temperatures exceeding 300°C and to obtain total fluid samples at supercritical conditions in the IDDP wells, we plan to trap fluids in fluid inclusions formed in fractured quartz that we suspend in a geothermal well on a wireline. In a series of hydrothermal laboratory experiments at 450°C and 600 bar and spanning 6 hr to 5 days in length, thermal shock fractures in natural and synthetic quartz crystals heal, forming ragged fluid inclusions in one day and many well formed inclusions in three days. Amorphous silica is added to the experimental charge, without which, fractures heal little and only 1-2 micron inclusions form. Microthermometry measurements on the inclusions produced in experiments return the run temperature within 20°C at the experimental pressure, indicating that inclusions formed and sealed at the run conditions. The fluid inclusion tool (FIT) consists of a perforated stainless steel pipe containing multiple stainless steel mesh canisters with non-mesh ends to minimize vertical fluid flow. The canisters contain 10mm-scale chunks of fractured quartz surrounded by ground quartz glass. The perforated pipe will be fixed within a one-meter outer perforated stainless steel housing that is suspended on a stainless steel slick line. The FIT is weighed by one or more 10kg lead sinker bars. The entire assembly is lowered into the well from a lubricator fitted on the wellhead, thus enabling sampling under high temperatures and pressures. In the initial field testing runs, the contents of the mesh canisters will be varied to examine the effects of ground glass grain size, and the suitability of clear natural quartz vs synthetic quartz, both with respect to fluid inclusion development and chemical analyses of inclusions. Inclusions will be analyzed by various bulk methods and by LA-ICP-MS on individual inclusions. Once we optimize the fluid inclusion tool configuration in field tests and by analytical results, the volume of sampling quartz can be scaled up as needed to provide for optimum sampling and analyses.

  6. Varicose Veins, Deep Vein Thrombosis, and Haemorrhoids: Epidemiology and Suggested Aetiology

    PubMed Central

    Burkitt, Denis P.

    1972-01-01

    Current concepts on the aetiology of varicose veins, deep vein thrombosis, and haemorrhoids have been examined and, in the light of epidemiological evidence, found wanting. It is suggested that the fundamental cause of these disorders is faecal arrest which is the result of a low-residue diet. PMID:5032782

  7. Internal vein texture and vein evolution of the epithermal Shila-Paula district, southern Peru

    E-print Network

    Paris-Sud XI, Université de

    Internal vein texture and vein evolution of the epithermal Shila-Paula district, southern Peru) CEDIMIN S.A.C., Luis N. Saenz 447-449, Jesus Maria, Lima 21, Peru (5) ISTO, CNRS-UMR 6113, University Cordillera (southern Peru). Field studies of the ore bodies reveal a systematic association of a main E

  8. Hepatocellular Carcinoma Invading the Main Portal Vein: Treatment with Transcatheter Arterial Chemoembolization and Portal Vein Stenting

    Microsoft Academic Search

    Zhang Xuebin; Wang Jianhua; Yan Zhiping; Qian Sheng; Liu Rong

    2009-01-01

    To retrospectively analyze the therapeutic results of percutaneous transhepatic portal vein stenting (PTPVS) and transcatheter arterial chemoembolization (TACE) treatment in 58 patients with hepatocellular carcinoma (HCC) invading the main portal vein (MPV). A total of 58 procedures of PTPVS were performed, immediately after which TACE was undertaken to control HCC. The clinical effects, complications, digital subtraction angiographic appearance, stent patency

  9. Deep vein thrombosis: a clinical review

    PubMed Central

    Kesieme, Emeka; Kesieme, Chinenye; Jebbin, Nze; Irekpita, Eshiobo; Dongo, Andrew

    2011-01-01

    Background: Deep vein thrombosis (DVT) is the formation of blood clots (thrombi) in the deep veins. It commonly affects the deep leg veins (such as the calf veins, femoral vein, or popliteal vein) or the deep veins of the pelvis. It is a potentially dangerous condition that can lead to preventable morbidity and mortality. Aim: To present an update on the causes and management of DVT. Methods: A review of publications obtained from Medline search, medical libraries, and Google. Results: DVT affects 0.1% of persons per year. It is predominantly a disease of the elderly and has a slight male preponderance. The approach to making a diagnosis currently involves an algorithm combining pretest probability, D-dimer testing, and compression ultrasonography. This will guide further investigations if necessary. Prophylaxis is both mechanical and pharmacological. The goals of treatment are to prevent extension of thrombi, pulmonary embolism, recurrence of thrombi, and the development of complications such as pulmonary hypertension and post-thrombotic syndrome. Conclusion: DVT is a potentially dangerous condition with a myriad of risk factors. Prophylaxis is very important and can be mechanical and pharmacological. The mainstay of treatment is anticoagulant therapy. Low-molecular-weight heparin, unfractionated heparin, and vitamin K antagonists have been the treatment of choice. Currently anticoagulants specifically targeting components of the common pathway have been recommended for prophylaxis. These include fondaparinux, a selective indirect factor Xa inhibitor and the new oral selective direct thrombin inhibitors (dabigatran) and selective factor Xa inhibitors (rivaroxaban and apixaban). Others are currently undergoing trials. Thrombolytics and vena caval filters are very rarely indicated in special circumstances. PMID:22287864

  10. The Modi Taung-Nankwe gold district, Slate belt, central Myanmar: mesothermal veins in a Mesozoic orogen

    NASA Astrophysics Data System (ADS)

    Mitchell, A. H. G.; Ausa, C. A.; Deiparine, L.; Hlaing, T.; Htay, N.; Khine, A.

    2004-07-01

    The recently discovered quartz-gold veins comprising the Modi Taung-Nankwe gold district in central Myanmar are largely hosted by mudstones of the late Palaeozoic Slate belt. Mesozoic rocks of the Paunglaung-Mawchi zone separate the Slate belt from the Shan Scarp and Shan Plateau to the east. At Modi Taung 5 km of exploration adits indicate that the veins, within steeply dipping oblique reverse-slip shear zones, are displaced by movements along the shears, intruded by late Jurassic calc-alkaline dykes, and offset on conjugate cross-faults. Drill intercepts show that mineralization extends vertically for more than 500 m. Coarse visible gold, book-and-ribbon texture and stylolitic laminations, and trace metal values are consistent with mineralization at mesothermal depths of several kilometres in the brittle-ductile regime. Our field observations suggest that mineralization took place in the early Jurassic following collision of Myanmar on the passive western margin of a Greater Shan-Thai continental block with an oceanic arc on the overriding plate to the west. Collision generated intra-continental thrusting in and east of the Paunglaung-Mawchi zone, metamorphism of Plateau rocks thrust west beneath the Slate belt to form the Mogok Metamorphics, and ascent of mineralizing fluids expelled from dehydrating underthrust rocks. Reversal in orogenic polarity initiated late Jurassic eastward subduction of oceanic crust beneath Myanmar, and generation of a magmatic arc with dykes cutting the quartz-gold veins. Renewed east-directed thrusting translated the Slate belt over arc clastics, and probably resulted in exhumation of the Mogok Metamorphics and offsets of the veins on conjugate faults. Young K/Ar, Rb 87/Sr 86 and Ar 40/Ar 39 ages on the Mogok Metamorphic belt imply renewed Tertiary uplift and possibly intrusion of mid-Tertiary or Palaeogene granites.

  11. Particle and substrate losses from Teflon® and quartz filters

    NASA Astrophysics Data System (ADS)

    Highsmith, V. Ross; Bond, Andrew E.; Howes, James E.

    Teflon® and quartz particulate matter samples were collected at two special study sites. In order to estimate changes in mass corresponding to the various filter handling operations (for TSP and PM 10 samples), changes in both controlled and shipped filter weights were monitored at predetermined stages of the filter handling process. The study data indicate that folding the quartz filters did not significantly change the filter mass even if the filter broke along the seam. A weight loss was noted following shipment of the TSP quartz filters but not the corresponding PM 10 quartz filters. Volatilization losses were also noted with the high volume samples collected at one city. Based on mass determinations, the quartz filters did not appear to be affected by passive artifact formation. No significant weight change occurred in the routine handling of the study dichotomous Teflon® filters. The results indicate that quartz and Teflon® filter media can be used in future particulate monitoring programs.

  12. Endovascular Radiofrequency Ablation for Varicose Veins

    PubMed Central

    2011-01-01

    Executive Summary Objective The objective of the MAS evidence review was to conduct a systematic review of the available evidence on the safety, effectiveness, durability and cost–effectiveness of endovascular radiofrequency ablation (RFA) for the treatment of primary symptomatic varicose veins. Background The Ontario Health Technology Advisory Committee (OHTAC) met on August 26th, 2010 to review the safety, effectiveness, durability, and cost-effectiveness of RFA for the treatment of primary symptomatic varicose veins based on an evidence-based review by the Medical Advisory Secretariat (MAS). Clinical Condition Varicose veins (VV) are tortuous, twisted, or elongated veins. This can be due to existing (inherited) valve dysfunction or decreased vein elasticity (primary venous reflux) or valve damage from prior thrombotic events (secondary venous reflux). The end result is pooling of blood in the veins, increased venous pressure and subsequent vein enlargement. As a result of high venous pressure, branch vessels balloon out leading to varicosities (varicose veins). Symptoms typically affect the lower extremities and include (but are not limited to): aching, swelling, throbbing, night cramps, restless legs, leg fatigue, itching and burning. Left untreated, venous reflux tends to be progressive, often leading to chronic venous insufficiency (CVI). A number of complications are associated with untreated venous reflux: including superficial thrombophlebitis as well as variceal rupture and haemorrhage. CVI often results in chronic skin changes referred to as stasis dermatitis. Stasis dermatitis is comprised of a spectrum of cutaneous abnormalities including edema, hyperpigmentation, eczema, lipodermatosclerosis and stasis ulceration. Ulceration represents the disease end point for severe CVI. CVI is associated with a reduced quality of life particularly in relation to pain, physical function and mobility. In severe cases, VV with ulcers, QOL has been rated to be as bad or worse as other chronic diseases such as back pain and arthritis. Lower limb VV is a very common disease affecting adults – estimated to be the 7th most common reason for physician referral in the US. There is a very strong familial predisposition to VV. The risk in offspring is 90% if both parents affected, 20% when neither affected and 45% (25% boys, 62% girls) if one parent affected. The prevalence of VV worldwide ranges from 5% to 15% among men and 3% to 29% among women varying by the age, gender and ethnicity of the study population, survey methods and disease definition and measurement. The annual incidence of VV estimated from the Framingham Study was reported to be 2.6% among women and 1.9% among men and did not vary within the age range (40-89 years) studied. Approximately 1% of the adult population has a stasis ulcer of venous origin at any one time with 4% at risk. The majority of leg ulcer patients are elderly with simple superficial vein reflux. Stasis ulcers are often lengthy medical problems and can last for several years and, despite effective compression therapy and multilayer bandaging are associated with high recurrence rates. Recent trials involving surgical treatment of superficial vein reflux have resulted in healing and significantly reduced recurrence rates. Endovascular Radiofrequency Ablation for Varicose Veins RFA is an image-guided minimally invasive treatment alternative to surgical stripping of superficial venous reflux. RFA does not require an operating room or general anaesthesia and has been performed in an outpatient setting by a variety of medical specialties including surgeons and interventional radiologists. Rather than surgically removing the vein, RFA works by destroying or ablating the refluxing vein segment using thermal energy delivered through a radiofrequency catheter. Prior to performing RFA, color-flow Doppler ultrasonography is used to confirm and map all areas of venous reflux to devise a safe and effective treatment plan. The RFA procedure involves the introduction of a guide wire into the target v

  13. Universal elastic-hardening-driven mechanical instability in ?-quartz and quartz homeotypes under pressure

    PubMed Central

    Dong, Juncai; Zhu, Hailiang; Chen, Dongliang

    2015-01-01

    As a fundamental property of pressure-induced amorphization (PIA) in ice and ice-like materials (notably ?-quartz), the occurrence of mechanical instability can be related to violation of Born criteria for elasticity. The most outstanding elastic feature of ?-quartz before PIA has been experimentally reported to be the linear softening of shear modulus C44, which was proposed to trigger the transition through Born criteria B3. However, by using density-functional theory, we surprisingly found that both C44 and C66 in ?-quartz exhibit strong nonlinearity under compression and the Born criteria B3 vanishes dominated by stiffening of C14, instead of by decreasing of C44. Further studies of archetypal quartz homeotypes (GeO2 and AlPO4) repeatedly reproduced the same elastic-hardening-driven mechanical instability, suggesting a universal feature of this family of crystals and challenging the long-standing idea that negative pressure derivatives of individual elastic moduli can be interpreted as the precursor effect to an intrinsic structural instability preceding PIA. The implications of this elastic anomaly in relation to the dispersive softening of the lowest acoustic branch and the possible transformation mechanism were also discussed. PMID:26099720

  14. Veining Failure and Hydraulic Fracturing in Shales

    NASA Astrophysics Data System (ADS)

    Mighani, S.; Sondergeld, C. H.; Rai, C. S.

    2014-12-01

    During the hydraulic fracturing, the pressurized fluid creates new fractures and reactivates existing natural fractures forming a highly conductive Stimulated Reservoir Volume (SRV) around the borehole. We extend the previous work on Lyons sandstone and pyrophyllite to anisotropic shale from the Wolfcamp formation. We divide the rock anisotropy into two groups: a) conventional and b) unconventional (shaly) anisotropy. X-ray Computed Tomography (CT), compressional velocity anisotropy, and SEM analysis are used to identify three causes of anisotropy: bedding planes, clay lamination, and calcite veins. Calcite vein is a subsequently filled with calcite bonded weakly to the matrix. Velocity anisotropy and visual observations demonstrate the calcite filled veins to be mostly subparallel to the fabric direction. Brazilian tests are carried out to observe the fracture initiation and propagation under tension. High speed photography (frame rate 300,000 frame/sec) was used to capture the failure. Strain gauges and Acoustic Emission (AE) sensors recorded the deformation leading up to and during failure. SEM imaging and surface profilometry were employed to study the post-failure fracture system and failed surface topology. Fracture permeability was measured as a function of effective stress. Brazilian tests on small disks containing a centered single vein revealed the shear strength of the veins. We interpret the strain data and number, frequency, and amplitude of AE events which are correlated well with the observed fracture process zone, surface roughness, and permeability. The unpropped fracture has enhanced permeability by two orders of magnitude. The observed anisotropic tensile failure seems to have a universal trend with a minimum strength occurring at 15o orientation with respect to the loading axis. The veins at 15o orientation with respect to the loading axis were easily activated at 30% of the original failure load. The measured strength of the vein is as low as 6% of the matrix. Surface roughness measurements show the vein to be as rough as the main tensile fracture in the matrix. The observations suggest that fracking through a deviated well reduces the breakdown pressure significantly and can activate a large number of veins with enhanced conductivity without the need for excessive proppant injection.

  15. [Surgical therapy of primary varicose veins].

    PubMed

    Wigger, P

    1998-11-01

    The principle of varicose vein surgery still remains the interruption of all insufficient communications between the deep and the superficial venous system and removal of the varicosities. The basis for differentiated surgical treatment is accurate preoperative assessment. Careful dissection of the saphenofemoral junction through a suprainguinal incision, with division of all the branches and flush tie of the long saphenous vein combined with invaginated stripping of the long saphenous vein to just below the knee, appears to be the method of choice for good clinical results and a low incidence of damage to the saphenous nerve. Oesch recently introduced a new technique of perforate invaginate (PIN) stripping which gives even better cosmetic results. Regarding the short saphenous vein, preoperative localization of the exact level of the saphenopopliteal junction is of major importance in the prevention of recurrence. Simple evulsion or epifascial or subfascial ligation were the most common treatments for incompetent perforating veins for many years. In 1985 Hauer described endoscopic subfascial dissection of perforating veins (ESDP), which reduces delayed wound healing, especially in trophic skin changes. Deprivation of blood supply with a pneumatic tourniquet such as the Löfqvist roller cuff is necessary. The tributaries are removed by stab evulsion phlebectomy with specially designed hooks. This technique was originally introduced by Muller for ambulatory treatment of varicose veins. The incisions of 1-3 mm guarantee excellent cosmesis and minimal trauma. Adhesive tape is used to close the incisions. A number of alternative techniques such as cryosurgery, laser surgery, paratibial fasciotomy and the CHIVA technique (Conservative Treatment and Haemodynamics in Venous Insufficiency in Outpatient Departments) are briefly described. Complications of varicose vein surgery are rare. Minor complications are skin nerve injuries, haematomas, infections and lymphatic fistulas. Major complications such as injuries to the femoral vein or artery occur in less than 0.05%. But once it has occurred it is of paramount importance to recognize the injury at the time of initial surgery, to avoid limb loss. Provided the preoperative assessment is accurate and the principles of selective surgical treatment are followed, the surgeon is able to perform a curative operation with a low complication rate and excellent cosmetic results. PMID:9854291

  16. Hydrothermal reactions of fly ash

    SciTech Connect

    Brown, P.W.

    1991-01-01

    The reactions which occur when fly ash is treated under hydrothermal conditions will be investigated. Formation of four classes of compounds, which bracket likely fly ash compositional ranges, have been selected for study. These are calcium silicate hydrates, calcium silicosulfates, calcium aluminosulfates, and alkali aluminosilicates. The specific compounds fabricated will be determined and their stability regions assessed. As a part of stability assessment, the extent to which selected hazardous species are sequestered will be determined. Finally, the cementing properties of these compounds will be established.

  17. Features of controlled laser thermal cleavage of crystal quartz

    NASA Astrophysics Data System (ADS)

    Serdyukov, A. N.; Shershnev, E. B.; Nikityuk, Yu. V.; Sholokh, V. F.; Sokolov, S. I.

    2012-11-01

    Controlled laser thermal cleavage of crystalline quartz has been simulated. The thermoelastic fields formed in a square single-crystal quartz plate as a result of successive laser heating and exposure to coolant have been calculated for five different versions specified by the crystal cut orientation and direction of laser beam displacement. The results have been verified experimentally using a CO2 laser. The simulation results can be used in the electronics industry to optimize laser cutting of quartz crystals.

  18. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, B.L.

    1996-11-19

    An optical furnace for annealing a process wafer is disclosed 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. 5 figs.

  19. Cathodoluminescence of shocked quartz at the Cretaceous-Tertiary boundary

    NASA Technical Reports Server (NTRS)

    Owen, Michael R.; Anders, Mark H.

    1988-01-01

    Empirical studies have documented an association between rock type and the cathodoluminescence color of constituent quartz grains. Quartz from extrusive igneous sources luminesces uniform pale blue. Quartz from intrusive igneous and high-grade metamorphic rocks generally luminesces darker purple-blue, whereas quartz recrystallized under low-grade metamorphic conditions luminesces reddish-brown. Quartz grains in most sandstones luminesce a heterogeneous mixture of these colors because the grains were derived from a variety of ultimate source rocks. If shocked quartz found at the Cretaceous-Tertiary (K-T) boundary is volcanic in origin, its cathodoluminescence should be predominantly pale blue. Alternatively, quartz grains derived from bolide impact upon, and ejection of, mixed igneous, metamorphic, and sedimentary rocks should luminesce a variety of colors. Grain mounts of sand collected at the K-T boundary horizon from the Clear Creek North site in the Raton Basin, Colorado were examined. Shocked quartz luminesced a variety of colors and very few grains luminesced the pale blue color that is typical of volcanic quartz. It was concluded that the shocked quartz was derived from a petrologically diverse source region without substantial volcanic contribution. Most shocked grains apparently were derived from low-grade metamorphic rocks, with a slightly smaller contribution from high-grade metamorphic and intrusive igneous rocks. Rare quartz grains with brown-luminescing rims reflect a minor addition from detrital sedimentary sources. The apparent relative abundances of intrusive (and rare extrusive) igneous, metamorphic, and sedimentary ultimate source rocks suggested by CL colors of shock-deformed quartz at the K-T boundary is consistent with a crustal/supracrustal origin for the grains.

  20. Hydrothermal diamond-anvil cell: Application to studies of geologic fluids

    USGS Publications Warehouse

    Chou, I.-Ming

    2003-01-01

    The hydrothermal diamond-anvil cell (HDAC) was designed to simulate the geologic conditions of crustal processes in the presence of water or other fluids. The HDAC has been used to apply external pressure to both synthetic and natural fluid inclusions in quartz to minimize problems caused by stretching or decrepitation of inclusions during microthermometric analysis. When the HDAC is loaded with a fluid sample, it can be considered as a large synthetic fluid inclusion and therefore, can be used to study the PVTX properties as well as phase relations of the sample fluid. Because the HDAC has a wide measurement pressure-temperature range and also allows in-situ optical observations, it has been used to study critical phenomena of various chemical systems, such as the geologically important hydrous silicate melts. It is possible, when the HDAC is combined with synchrotron X-ray sources, to obtain basic information on speciation and structure of metal including rare-earth elements (REE) complexes in hydrothermal solutions as revealed by X-ray absorption fine structure (XAFS) spectra. Recent modifications of the HDAC minimize the loss of intensity of X-rays due to scattering and absorption by the diamonds. These modifications are especially important for studying elements with absorption edges below 10 keV and therefore particularly valuable for our understanding of transport and deposition of first-row transition elements and REE in hydrothermal environments.

  1. Hydrothermal synthesis of {beta}-nickel hydroxide nanocrystalline thin film and growth of oriented carbon nanofibers

    SciTech Connect

    Zhang Enlei [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Tang Yuanhong, E-mail: yhtang2000@163.com [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China) and Powder Metallurgy Research Institute, Central South University, Changsha 410083 (China); Zhang Yong; Guo Chi; Yang Lei [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

    2009-08-05

    Novel well-crystallized {beta}-nickel hydroxide nanocrystalline thin films were successfully synthesized at low temperature on the quartz substrates by hydrothermal method, and the oriented carbon nanofibers (CNFs) were prepared by acetylene cracking at 750 deg. C on thin film as the catalyst precursor. High resolution transmission electron microscopy (HR-TEM) measurement shows that thin films were constructed mainly with hexagonal {beta}-nickel hydroxide nanosheets. The average diameter of the nanosheets was about 80 nm and thickness about 15 nm. Hydrothermal temperature played an important role in the film growth process, influencing the morphologies and catalytic activity of the Ni catalysts. Ni thin films with high catalytic activity were obtained by reduction of these Ni(OH){sub 2} nanocrystalline thin films synthesized at 170 deg. C for 2 h in hydrothermal condition. The highest carbon yield was 1182%, and was significantly higher than the value of the catalyst precursor which was previously reported as the carbon yield (398%) for Ni catalysts. The morphology and growth mechanism of oriented CNFs were also studied finally.

  2. Optimization of subcutaneous vein contrast enhancement

    NASA Astrophysics Data System (ADS)

    Zeman, Herbert D.; Lovhoiden, Gunnar; Deshmukh, Harshal

    2000-05-01

    A technique for enhancing the contrast of subcutaneous veins has been demonstrated. This techniques uses a near IR light source and one or more IR 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 a n LCD video projector. The use of an IR 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 and children, both Caucasian and African-American, and it enhances veins quite well in all cases. The most difficult cases are those where significant deposits of subcutaneous fat are present which make the veins invisible under normal room illumination. Recent attempts to see through fat using different IR wavelength bands and both linearly and circularly polarized light were unsuccessful. The key to seeing through fat turns out to be a very diffuse source of RI light. Results on adult and pediatric subjects are shown with this new IR light source.

  3. Fluid inclusion studies of the Chinkuashih high-sulfidation gold–copper deposits in Taiwan

    Microsoft Academic Search

    Yunshuen Wang; Munetake Sasaki; Masakatsu Sasada; Cheng-Hong Chen

    1999-01-01

    Epithermal high-sulfidation Au–Cu deposits at Chinkuashih in northeastern Taiwan are found both within Pleistocene calc-alkaline volcanic rocks and the Miocene sedimentary rocks. The deposits consist of gold–copper veins of the Penshan group and breccia pipes of the Tushihshan–Changjen group. Primary two-phase inclusions in hydrothermal quartz and secondary two-phase inclusions in hydrothermal quartz as well as igneous quartz phenocrysts probably represent

  4. Comparative study of yttrium and rare-earth element behaviours in fluorine-rich hydrothermal fluids

    NASA Astrophysics Data System (ADS)

    Bau, Michael; Dulski, Peter

    1995-03-01

    The mineral ‘fluorite’ is utilized as a probe to investigate the behaviour of the pseudolanthanide yttrium with respect to the lanthanides (rare-earth elements, REE) in fluorine-rich hydrothermal solutions. Hydrothermal vein fluorites are characterized by the close association of Y and REE, but in contrast to igneous and clastic rocks they show variable and non-chondritic Y/Ho ratios of up to 200. This suggests that Y and Ho, although similar in charge and size, may be fractionated in fluorine-rich medium-temperature aqueous fluids. In such solutions Y acts as a pseudolanthanide heavier than Lu. Y/Ho ratios of hydrothermal siderites are slightly below those of chondrites, suggesting that in (bi)carbonate-rich siderite-precipitating solutions Y may act as a Sm-like light pseudolanthanide. This indicates that Y-Ho fractionation is not a source-related phenomenon but depends on fluid composition. Based on these results it is strongly recommended that discussions of normalized REE patterns in general should be extended to normalized Rare-Earth-and-Yttrium (REY) patterns (Y inserted between Dy and Ho), because the slightly variable behaviour of the pseudolanthanide yttrium with respect to the REE may provide additional geochemical information. Available thermodynamic data suggest a negative correlation between Y/Ho and La/Ho during migration of a fluorite-precipitating hydrothermal solution. Cogenetic fluorites, therefore, should display either similar Y/Ho and similar La/Ho ratios, or a negative correlation between these ratios. This criterion may help to choose samples suitable for Sm-Nd isotopic studies prior to isotope analysis. However, in cogenetic hydrothermal vein fluorites the range of Y/Ho ratios is often almost negligible compared to the range of La/Ho ratios. This may be explained by modification of REE distributions by post-precipitation processes involving (partial) loss of a separate LREE-enriched phase. The presence of variable amounts of such an accessory phase in most fluorite samples is revealed by experiments employing stepwise incomplete fluorite decomposition. Fluorites derived from and deposited near to igneous rocks apparently display chondritic Y/Ho ratios close to those of their igneous source-rocks. However, a positive YSN anomaly is likely to develop as the distance between sites of REY mobilization and deposition increases.

  5. Meta-igneous (non-gneissic) tonalites and quartz-diorites from an extensive ca. 3800 Ma terrain south of the Isua supracrustal belt, southern West Greenland: constraints on early crust formation

    Microsoft Academic Search

    Allen P. Nutman; Vickie C. Bennett; Clark R. L. Friend; Marc D. Norman

    1999-01-01

    In the Itsaq Gneiss Complex south of the Isua supracrustal belt (West Greenland) some areas of early Archaean tonalite and\\u000a quartz-diorite are non-gneissic, free of pegmatite veins, and in rarer cases are undeformed with relict igneous textures and\\u000a hence were little modified by heterogeneous ductile deformation under amphibolite facies conditions in several Archaean events.\\u000a Such well-preserved early Archaean rocks are

  6. Anteriorly placed splenic vein: a case report.

    PubMed

    Lal, Hira; Boruah, Deb K; Yadav, Ankusha; Samal, Amrita

    2015-04-01

    Splenic vein located anterior to pancreas is a rare congenital anomaly. To date, only one case has been reported in literature. A thorough knowledge of the normal anatomy, most frequent variations, and congenital and acquired anomalies of the spleno-portal axis is of great importance for hepatobiliary and pancreatic surgeons. It is therefore essential for preoperative evaluation of the anatomical details of the spleno-portal venous axis to be made by imaging. We report such a case of anteriorly placed splenic vein in a 40-year-old female prospective renal donor. To the best of our knowledge, this represents the second reported case of an anteriorly placed splenic vein. PMID:25972673

  7. Technical aspects of adrenal vein sampling.

    PubMed

    Harsha, Asheesh; Trerotola, Scott O

    2015-02-01

    The most common cause of secondary hypertension is primary aldosteronism, with a prevalence of approximately 30% when screened by specialized hypertension clinics. Adrenal venous sampling is considered the standard for reliably distinguishing between unilateral and bilateral hormone secretion, with unilateral secretion being surgically curable. Success of adrenal vein sampling relies on appropriate patient selection, patient preparation, and recognition and catheterization of both adrenal veins. However, this procedure may prove technically challenging, particularly for inexperienced operators. This video (see Fig; available online at www.jvir.org) is designed to provide the viewer with details on the technical aspects of adrenal vein sampling by using the sequential technique in an immersive format with real-time table-top teaching. Indications, patient preparation, equipment selection, technique, and quality assurance are reviewed in detail, with the goal of providing practitioners an opportunity to successfully incorporate this procedure into their practice. PMID:25645412

  8. Hydrothermal reactions of fly ash

    SciTech Connect

    Brown, P.W.

    1992-01-01

    The reactions which occur when fly ash is treated under hydrothermal conditions will be investigated. This will be done for two primary reasons. The first of these is to determine the nature of the phases that form, to assess the stabilities of these phases in the ambient environment and, finally, to assess whether these phases are capable of sequestering hazardous species. The second reason for undertaking this proposed study is that, depending on the composition of the ash and the presence of selected additives, it may be possible under hydrothermal conditions to form compounds which have cementitious properties. Formation of four classes of compounds which bracket likely fly ash compositional ranges, have been selected for study. These are calcium silicate hydrates, calcium silicosulfates, calcium aluminosulfates, and alkali aluminosilicates. The specific compounds fabricated will be determined and their stability regions assessed. As a part of stability assessment, the extent to which selected hazardous species are sequestered seal be determined. Finally, the cementing properties of these compounds will be established.

  9. Ongoing hydrothermal activities within Enceladus.

    PubMed

    Hsu, Hsiang-Wen; Postberg, Frank; Sekine, Yasuhito; Shibuya, Takazo; Kempf, Sascha; Horányi, Mihály; Juhász, Antal; Altobelli, Nicolas; Suzuki, Katsuhiko; Masaki, Yuka; Kuwatani, Tatsu; Tachibana, Shogo; Sirono, Sin-iti; Moragas-Klostermeyer, Georg; Srama, Ralf

    2015-03-12

    Detection of sodium-salt-rich ice grains emitted from the plume of the Saturnian moon Enceladus suggests that the grains formed as frozen droplets from a liquid water reservoir that is, or has been, in contact with rock. Gravitational field measurements suggest a regional south polar subsurface ocean of about 10 kilometres thickness located beneath an ice crust 30 to 40 kilometres thick. These findings imply rock-water interactions in regions surrounding the core of Enceladus. The resulting chemical 'footprints' are expected to be preserved in the liquid and subsequently transported upwards to the near-surface plume sources, where they eventually would be ejected and could be measured by a spacecraft. Here we report an analysis of silicon-rich, nanometre-sized dust particles (so-called stream particles) that stand out from the water-ice-dominated objects characteristic of Saturn. We interpret these grains as nanometre-sized SiO2 (silica) particles, initially embedded in icy grains emitted from Enceladus' subsurface waters and released by sputter erosion in Saturn's E ring. The composition and the limited size range (2 to 8 nanometres in radius) of stream particles indicate ongoing high-temperature (>90 °C) hydrothermal reactions associated with global-scale geothermal activity that quickly transports hydrothermal products from the ocean floor at a depth of at least 40 kilometres up to the plume of Enceladus. PMID:25762281

  10. Formation of viable nuclei and particle growth in hydrothermal processing of silicon dioxide wafers: A modeling study of entrance effects

    SciTech Connect

    Chitanvis, S.M.

    1994-08-01

    A major problem that besets rapid hydrothermal processing of silicon dioxide wafers is the formation of particles. In this report we have used The Becker, Doering, Zeldovich theory of homogeneous condensation of viable nuclei to study particle formation in a hydrothermal processing chamber. We have further utilized a diffusive growth model that allows these nuclei to develop into larger particles. In addition, we have developed a model to partially dissolve the walls of the quartz chamber into the steam flowing by. The interplay between homogeneous nucleation and inhomogeneous nucleation is brought out via a dimensionless number that is the ratio of the timescales of these two phenomena. An analytic model was developed to prove in consonance with numerical results that unless the incoming stream is itself supersaturated, there will be no nucleation near the entrance.

  11. How Vein Sealing Boosts Fracture Opening

    NASA Astrophysics Data System (ADS)

    Nüchter, Jens-Alexander

    2015-04-01

    Veins from from cracks. As such, a stage of brittle failure and fracturing is to be set apart from a stage of opening and sealing. The process of fracture opening requires distortion of the host rocks to create space for the evolving vein. To keep a crack arrested and, at the same time, to widen or stabilize the cavity, the stress intensity factor K_I=(P-S3)(?a) must remain below the fracture toughness K_IC of the host rock, and P-S3 >0 (P and S3 denote pore fluid pressure and absolute minimum principal stress, respectively and 'a' refers to the half-length of the fracture). For purely elastic distortion of the host rocks, maximum aperture W0=K_IC (1-?^2)/(E(?/8)^1/2))(2a)^1/2 depends on on K_IC, Poisson's ratio ?, and Young's modulus E of the host rocks. Owing to the low values for rock K_IC typically ranging between 0.1 and 1 MPa m^1/2, veins formed by purely elastic distortion of the host rocks are restricted to high aspect ratios 2a/W. In metamorphic rocks, veins with low aspect ratios are common; inelastic deformation and viscous creep in the host rocks must have contributed to final vein shapes. In the present study, I use finite element models to simulate fracture opening and cavity formation supported by viscous creep distributed in the host rock. Simulations are carried out on 2D plate models containing elliptical fractures. The walls of the fractures are coated by thin layers simulating incipient sealing; a residual cavity prevails in the centre of the model veins. Constant displacement is applied to the plate boundaries oriented normal to the cracks. I run a series of models with various viscosity contrasts between the rocks and the sealing. The results of these models indicate the following. (1) Fracture opening is most effective when the viscosity of the sealing ?s exceeds the viscosity of the host rocks ?r (2) The rate of fracture opening increases with increasing values for ?s/?r . (3) An increase in the thickness of the sealing layer causes an increase in the fracture opening rates. (4) At constant strain rates, the rate of fracture opening increases with increasing strain. These results suggest that vein sealing boosts the rate of fracture opening, and contributes to development of low-aspect ratio veins.

  12. The origin and evolution of base metal mineralising brines and hydrothermal fluids, South Cornwall, UK

    NASA Astrophysics Data System (ADS)

    Gleeson, S. A.; Wilkinson, J. J.; Stuart, F. M.; Banks, D. A.

    2001-07-01

    A fluid inclusion geochemical study has been carried out on quartz from post-Variscan quartz ± carbonate ± base metal sulphide ± anhydrite ± fluorite veins hosted by Palaeozoic basement (Porthleven, Menheniot, Cornwall) and Permo-Triassic sediments (Western Approaches). Data indicate that the base metal mineralising fluids have a similar bulk chemical composition to the saline fluids found in the Permo-Triassic basinal sequence and support the hypothesis that these basins are the source of the mineralising fluids. Cl and Br systematics suggest that the brines were formed either by the evaporation of seawater or a seawater-meteoric water mixture past the point of halite precipitation. The major cation composition (Na, Ca, K, Mg) of the brines is not consistent solely with evaporation processes but may be explained by dolomitisation processes, albitisation processes, or both, which are recognised in the basinal sequences. The presence of seawater in the base metal mineralised veins suggests that the first marine incursions (Late Triassic) into the region must act as a lower age limit for the mineralisation. The halogen chemistry of a second, hotter (200°C), more dilute (0-5 wt.%) fluid identified in fault-hosted E-W trending veins in the Porthleven area, suggests that the chlorinity of these fluids has a magmatic origin. Circulation of these fluids in post-Variscan extensional structures was driven by the local high-heat-producing Cornubian batholith. The local high-heat-producing granites provided fracture permeability and a heat source that heated the base metal mineralising fluids as they entered the horst block and the dilute fluids circulating around the granites. Petrographic evidence suggests that both palaeohydrologic systems were active contemporaneously. However, each flow system was isolated in differently orientated structures, and there is little evidence for fluid mixing.

  13. Hydrothermal Alteration of the Lower Oceanic Crust: Sr Isotopic Constraints from the CCSP CY-4 Drill Hole, Troodos Ophiolite, Cyprus

    NASA Astrophysics Data System (ADS)

    King, L. E.; Teagle, D. A.; Cooper, M. J.; Alt, J. C.

    2003-12-01

    Our understanding of the structure and geometry of mid-ocean ridge hydrothermal systems is severely hindered by a dearth of continuous samples into the plutonic complexes of the ocean crust as it is this region that provides the power to drive hydrothermal circulation and preserves a record of magma chamber processes. Although the Troodos ophiolite most probably formed in a supra-subduction zone environment, its well-preserved outcrops have made an invaluable contribution to our understanding of ocean ridge processes. CY-4 drilled as part of the Cyprus Crustal Study Project provides a unique continuous sample of 2263 m of the lower Troodos crust. The hole was initiated in sheeted dikes before grading into isotropic gabbros around 675 m. An intrusive transition is evident at 1330 m between the isotropic gabbros and lower layered gabbros, pyroxenites and crustal peridotites. Petrographic observations and strontium isotopic analyses presented here investigate the incursion of seawater derived hydrothermal fluids into the lower oceanic crust. Previous studies of the Troodos ophiolite have determined the primary igneous composition of the magmas (87Sr/86Sr =0.7032-0.7040) and the range of hydrothermal fluids (87Sr/86Sr =0.7047-0.7059). Samples from the sheeted dike complex are variably altered with strontium isotopic compositions elevated above the primary igneous signatures of the Troodos magmas but generally lower than the restricted hydrothermal range observed for dikes throughout the rest of the ophiolite. Samples proximal to the sheeted dike - gabbro boundary do yield strontium isotope ratios within the hydrothermal fluid range. Within a few hundred metres below the dike-gabbro transition most samples yield near primary strontium isotopic ratios suggesting only limited pervasive penetration of seawater-derived Sr. Most samples down to the bottom of the hole show little increase in Sr ratios. Rare hydrothermally altered samples with associated veins and secondary halos have 87Sr/86Sr elevated towards hydrothermal values indicating significant channelling of hydrothermal fluids at deeper levels in the Troodos crust.

  14. OH zoning in alpine quartz from Austria

    NASA Astrophysics Data System (ADS)

    Hertweck, B.; Niedermayr, G.; Beran, A.

    2003-04-01

    Rock crystals from various alpine clefts in Austria were investigated in terms of morphology, domain structure, and OH defects. Since the formation of alpine clefts is a long lasting and multiphase process, the crystal growth of alpine quartz is dominated by different morphologies and various OH defects. 140 samples were investigated by FTIR spectroscopy and optical methods to reveal complementary information on morphology, twining, hydrogen incorporation, and zoning of the OH defects. IR spectroscopic measurements of colourless and smoky quartz samples revealed six characteristic absorption bands in the range of the OH stretching frequencies at 3315, 3380, 3430, 3480, 3510 and 3595 cm-1. The quantitative analysis of the water content revealed an amount of 0.5-20 ppm H_2O. With a maximum of frequency in the 1-2 ppm range the amount of water incorporation is comparably lower than known from non-alpine deposits. The spectra can be divided in four types characterised by the number and/or the relative band intensities. Among the Austrian samples one type, showing clearly all the six bands, is abundant and has not been found in the spectra from non-alpine sites. A significant relation between spectra type, crystal morphology, mineral deposit (within Austria), and OH content cannot be deduced. Microspectroscopic measurements of profiles through crystals cut perpendicular to the c-axis revealed that the spectra types rarely change within one sample. However, a variation of the water content is commonly related to a change of the relative intensity of the 3480 cm-1 absorption band. Regarding the hydrogen incorporation all samples show a distinct zoning. In addition, the OH zoning as well as the crystal growth appear regularly, leading to different hydrogen amounts in core and mantle zone of the crystals. The average zoning is given by factor 1.2, whereas strong variations were measured up to factor 2.5. The formation of Brazil twin domains often coincides with a distinct change of the water content within one crystal. Such coincidences were not measured with other structural phenomena such as lamellar structure or colour zoning in smoky quartz. A dependency of the hydrogen incorporation from regional metamorphic grades of the host rocks, as known from the Swiss Alps (Bambauer et al., 1962), cannot be derived. Bambauer, H.U., Brunner, G.O. &Laves, F. (1962). Wasserstoff-Gehalte in Quarzen aus Zerrklüften der Schweizer Alpen und die Deutung ihrer regionalen Abhängigkeit. Schweiz. Min. Petr. Mitt. 42, 221-236.

  15. Dynamics of the Yellowstone hydrothermal system

    USGS Publications Warehouse

    Hurwitz, Shaul; Lowenstern, Jacob B.

    2014-01-01

    The Yellowstone Plateau Volcanic Field is characterized by extensive seismicity, episodes of uplift and subsidence, and a hydrothermal system that comprises more than 10,000 thermal features, including geysers, fumaroles, mud pots, thermal springs, and hydrothermal explosion craters. The diverse chemical and isotopic compositions of waters and gases derive from mantle, crustal, and meteoric sources and extensive water-gas-rock interaction at variable pressures and temperatures. The thermal features are host to all domains of life that utilize diverse inorganic sources of energy for metabolism. The unique and exceptional features of the hydrothermal system have attracted numerous researchers to Yellowstone beginning with the Washburn and Hayden expeditions in the 1870s. Since a seminal review published a quarter of a century ago, research in many fields has greatly advanced our understanding of the many coupled processes operating in and on the hydrothermal system. Specific advances include more refined geophysical images of the magmatic system, better constraints on the time scale of magmatic processes, characterization of fluid sources and water-rock interactions, quantitative estimates of heat and magmatic volatile fluxes, discovering and quantifying the role of thermophile microorganisms in the geochemical cycle, defining the chronology of hydrothermal explosions and their relation to glacial cycles, defining possible links between hydrothermal activity, deformation, and seismicity; quantifying geyser dynamics; and the discovery of extensive hydrothermal activity in Yellowstone Lake. Discussion of these many advances forms the basis of this review.

  16. Hydrothermal upgrading of algae paste in a continuous flow reactor.

    PubMed

    Patel, Bhavish; Hellgardt, Klaus

    2015-09-01

    This investigation demonstrates the utility of a novel laboratory scale continuous plug flow reactor for fast Hydrothermal Liquefaction (HTL) of microalgae in a quartz lined chamber. Reactions were carried out between 300 and 380°C and residence times of 0.5-4min. Cyclohexane was used as a co-solvent to enhance extraction and prevent char formation. Highest biocrude yield of 38wt.% was achieved at 380°C and 30s as well as Water Soluble Fraction containing up to 60wt.% matter recovered. Analysis of the biocrude showed that the extent of deoxygenation and denitrogenation after HTL varied and is dependent on the reaction conditions, Fourier Transform Infrared Spectroscopy analysis showed that biocrude contains similar functional moieties with only a small difference observed at different reaction conditions. Conversely, the Simulated Distillation and Size Exclusion Chromatography data showed that harsher conditions produced marginally better biocrude with improved boiling point profile and lower molecular weight compounds, respectively which was confirmed using Gas Chromatography-Mass Spectrometry. PMID:25908412

  17. Disseminated sulphides in basalts from the northern Central Indian Ridge: implications on late-stage hydrothermal activity

    NASA Astrophysics Data System (ADS)

    Banerjee, Ranadip; Ray, Dwijesh

    2015-04-01

    This study examined the mineralogy and mineral chemistry of disseminated sulphides (mainly chalcopyrite-pyrite) in partly altered basalts from the northern Central Indian Ridge, Indian Ocean in order to understand the role of hydrothermal alterations and infer possible sulphide formation history. Pyrite and chalcopyrite are dominant sulphide minerals and generally associated with the oxide phases including magnetite and often ilmenite. Close association of sulphide and oxide minerals suggests that they are paragenetically related. Sulphides also occur as late impregnated veins cutting through the basaltic hosts. The chemical compositions of pyrite (avg. Fe 46.3 wt%, S 53.7 wt%) and chalcopyrite (avg. Cu 34.4 wt%, Fe 30.7 wt%, S 34.7 wt%) are almost uniform, while the secondary ilmenite often shows MnO enrichment (up to 3.0-3.4 wt%). The associated altered minerals typically resemble the greenschist facies mineral assemblages—e.g. chlorite±epidote. Evidence of albitisation and silicification suggests low-temperature hydrothermal alteration processes. This is supported by the bulk Au content (up to 60 ppb) of host-altered basalts with pyrite mineralisation. Au is usually associated with late-stage pyrites and thus related with low-temperature hydrothermal activity. Close to the dredge location, tectonic activity around the Vityaz megamullion might have promoted hydrothermal circulation and subsequent alteration of the mineral constituents in basalts, eventually inducing the formation of late-stage disseminated sulphide minerals in these rocks.

  18. Seawater bicarbonate removal during hydrothermal circulation

    NASA Astrophysics Data System (ADS)

    Proskurowski, G. K.; Seewald, J.; Sylva, S. P.; Reeves, E.; Lilley, M. D.

    2013-12-01

    High temperature fluids sampled at hydrothermal vents represent a complex alteration product of water-rock reactions on a multi-component mixture of source fluids. Sources to high-temperature hydrothermal samples include the 'original' seawater present in the recharge limb of circulation, magmatically influenced fluids added at depth as well as any seawater entrained during sampling. High-temperature hydrothermal fluids are typically enriched in magmatic volatiles, with CO2 the dominant species, characterized by concentrations of 10's-100's of mmol/kg (1, 2). Typically, the high concentration of CO2 relative to background seawater bicarbonate concentrations (~2.3 mmol/kg) obscures a full analysis of the fate of seawater bicarbonate during high-temperature hydrothermal circulation. Here we present data from a suite of samples collected over the past 15 years from high-temperature hydrothermal vents at 9N, Endeavour, Lau Basin, and the MAR that have endmember CO2 concentrations less than 10 mmol/kg. Using stable and radiocarbon isotope measurements these samples provide a unique opportunity to examine the balance between 'original' seawater bicarbonate and CO2 added from magmatic sources. Multiple lines of evidence from multiple hydrothermal settings consistently points to the removal of ~80% of the 'original' 2.3 mmol/kg seawater bicarbonate. Assuming that this removal occurs in the low-temperature, 'recharge' limb of hydrothermal circulation, this removal process is widely occurring and has important contributions to the global carbon cycle over geologic time. 1. Lilley MD, Butterfield DA, Lupton JE, & Olson EJ (2003) Magmatic events can produce rapid changes in hydrothermal vent chemistry. Nature 422(6934):878-881. 2. Seewald J, Cruse A, & Saccocia P (2003) Aqueous volatiles in hydrothermal fluids from the Main Endeavour Field, northern Juan de Fuca Ridge: temporal variability following earthquake activity. Earth and Planetary Science Letters 216(4):575-590.

  19. Why should we report posterior fossa emissary veins?

    PubMed Central

    Pekçevik, Yeliz; Pekçevik, R?dvan

    2014-01-01

    Posterior fossa emissary veins are valveless veins that pass through cranial apertures. They participate in extracranial venous drainage of the posterior fossa dural sinuses. The mastoid emissary vein, condylar veins, occipital emissary vein, and petrosquamosal sinus are the major posterior fossa emissary veins. We believe that posterior fossa emissary veins can be detected by radiologists before surgery with a thorough understanding of their anatomy. Describing them using temporal bone computed tomography (CT), CT angiography, and cerebral magnetic resonance (MR) venography examinations results in more detailed and accurate preoperative radiological interpretation and has clinical importance. This pictorial essay reviews the anatomy of the major and clinically relevant posterior fossa emissary veins using high-resolution CT, CT angiography, and MR venography images and discusses the clinical importance of reporting these vascular variants. PMID:24047723

  20. What Are the Signs and Symptoms of Varicose Veins?

    MedlinePLUS

    ... around the varicose vein. Signs of telangiectasias are clusters of red veins that you can see just under the surface of your skin. These clusters usually are found on the upper body, including ...

  1. Quartz dissolution in organic-rich aqueous systems

    Microsoft Academic Search

    P BENNETT

    1991-01-01

    Organic electrolytes are a common component of natural waters and are known to be important in many rock-water interactions. The influence of organic electrolytes on silica mobility, quartz solubility, and quartz dissolution kinetics, however, is less well understood, While there is mounting evidence supporting the presence of an aqueous organic-silica complex in natural waters, the significance of this species is

  2. Quartz Plate Calorimeter as SLHC Upgrade to CMS Hadronic Endcap

    E-print Network

    Akgun, Ugur

    , CALOR 2008, Pavio, Italy 3 #12;Current Design: "Scintillators" · Megatiles of large scintillator sheets, CALOR 2008, Pavio, Italy 1 (on behalf of CMS Collaboration) #12;Outline · Introduction · Radiation on Cerenkov Light Collection on Quartz Plates. · Quartz Plate Calorimeter Prototype ­ I · Radiation Hard Light

  3. U. Akgun, ECLIPSE06, Antalya, Quartz Plate Calorimeter Prototype

    E-print Network

    Akgun, Ugur

    U. Akgun, ECLIPSE06, Antalya, Turkey Quartz Plate Calorimeter Prototype "First Generation" U. Akgun. Onel The University of Iowa #12;U. Akgun, ECLIPSE06, Antalya, Turkey Introduction · While working for the first time this summer at CERN. #12;U. Akgun, ECLIPSE06, Antalya, Turkey Model Quartz Plate Prototype

  4. Fiber optic pressure sensor based on quartz force transducers

    Microsoft Academic Search

    Russell N. Bigelow; James M. Sadler; Terry M. Stapleton; Mei H. Sun; Kenneth A. Wickersheim; Joseph P. Ingold

    1993-01-01

    A fiber optic pressure sensor is being developed for the Naval Surface Warfare Center- Dahlgren Division for use in measuring the pressure within sonar domes of Naval ships. The sensor comprises a quartz crystal tuning fork and force transduction mechanism such that the frequency of the quartz crystal is proportional to pressure within the sonar dome. An optical fiber interface

  5. Excitation and Attenuation of Hypersonic Waves in Quartz

    Microsoft Academic Search

    H. E. Bömmel; K. Dransfeld

    1960-01-01

    A method for the generation and detection of hypersonic waves, which has only been briefly described earlier, together with some absorption measurements in quartz, is discussed in some detail. Further measurements of the hypersonic absorption in quartz at different crystal orientations and after neutron irradiation are reported. The results are in qualitative agreement with a phonon-phonon relaxation process.

  6. Determination of oil quality using a quartz crystal microbalance

    Microsoft Academic Search

    Jianfeng Zhang; Youyun Zhang

    2001-01-01

    A method based on a quartz crystal microbalance (QCM) was used for the first time to analyze oil quality on line. When the QCM is immersed in the oil, the resonant frequency will change according to the change of viscosity, density of oil on the crystal electrode. According to this principle, Quartz Crystal Microbalance (QCM) with temperature sensor is a

  7. Fouling of quartz surfaces in potable water ultraviolet disinfection reactors

    Microsoft Academic Search

    Isaac William Wait

    2005-01-01

    Although ultraviolet (UV) disinfection of drinking water has been shown to be effective and cost efficient, one barrier to more widespread adoption is uncertainty surrounding the possible accumulation of fouling materials on quartz surfaces within UV reactors. These quartz surfaces serve as protection for the UV lamps that are immersed in the water being treated, and in many cases they

  8. Development of exhaled breath assay devices using Functionalized Quartz sensors

    Microsoft Academic Search

    A. I. Palaniappan; T. A. L. Melissa; S. Moochhala; F. E. H. Tay; S. G. Mhaisalkar

    2008-01-01

    This paper emphasizes on development of a sensitive and low cost exhaled breath assay device for clinical applications. Functionalized Quartz Crystal Microbalance (QCM) is used as the sensing platform to identify and quantify various bio-markers in the exhaled breath. Heme-based receptors, organic receptors, etc., will be functionalized on the quartz crystal electrodes to obtain the finger print of the various

  9. Catastrophic volcanic collapse: relation to hydrothermal processes.

    PubMed

    López, D L; Williams, S N

    1993-06-18

    Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of hydrothermal discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between hydrothermal fluids and the volcanic edifice. Rock dissolution and hydrothermal mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes. PMID:17793659

  10. Dive and Discover's Deeper Discovery: Hydrothermal Vents

    NSDL National Science Digital Library

    Dive and Discover is an interactive distance learning web site designed to immerse you in the excitement of discovery and exploration of the deep seafloor. On this particular website, Dive and Discover takes you on a deeper discovery of hydrothermal vents. This site features an introduction to hydrothermal vent systems, including vent basics, vents around the world, chemistry, boiling points, interactive diagrams, videos, a quiz, and links to selected Dive and Discover hydrothermal vent-related seafloor expeditions. This web page also provides links to other Deeper Discovery topics, Dive and Discover seafloor expeditions, a teacher's page, and further Dive and Discover information.

  11. Geochemistry of hot springs in the Tengchong hydrothermal areas, Southwestern China

    NASA Astrophysics Data System (ADS)

    Guo, Qinghai; Wang, Yanxin

    2012-02-01

    As an important volcanic geothermal region in China, Tengchong belongs to the Mediterranean-Himalayas geothermal belt and is characterized by wide distribution of volcanic rocks. Fifty-eight hydrothermal areas have been identified in Tengchong, among which the Rehai hydrothermal system is the most geothermally active. The geothermal waters from Rehai are mainly Na-HCO3-Cl and Na-HCO3 types, whereas those from the other hydrothermal areas are mainly Na-HCO3, Na-Ca-HCO3, Ca-HCO3, Ca-Mg-HCO3, Mg-Na-Ca-HCO3, and Mg-Ca-HCO3 types. Both quartz geothermometer and K-Mg geothermometer indicate that the Rehai geothermal field has higher subsurface temperatures than the other hydrothermal areas. Except for three Rehai samples, most geothermal water samples collected from Tengchong are far from the full equilibrium line in Giggenbach's triangular diagram, suggesting that the complete chemical re-equilibrium has not been achieved as these geothermal waters flow upward from reservoirs towards spring vents and possibly mix with cooler waters. Statistical analysis shows that Cl, B, Li, Rb, and Cs are the characteristic constituents of the Tengchong geothermal waters, and the good linear relations among these elements in the Rehai geothermal waters reflect the existence of a deep parent geothermal liquid (PGL) below Rehai. An enthalpy-chloride diagram of the Rehai geothermal waters suggests that the parent geothermal liquid has Cl-concentration of 291 mg/L and enthalpy of 1495 J/g. The PGL ascends to the surface through different channels and may cool by conduction of heat to reservoir host rocks, by boiling, or by mixing with cooler shallow groundwaters.

  12. Quartz Enhanced Photoacoustic Spectroscopy Based Trace Gas Sensors Using Different Quartz Tuning Forks

    PubMed Central

    Ma, Yufei; Yu, Guang; Zhang, Jingbo; Yu, Xin; Sun, Rui; Tittel, Frank K.

    2015-01-01

    A sensitive trace gas sensor platform based on quartz-enhanced photoacoustic spectroscopy (QEPAS) is reported. A 1.395 ?m continuous wave (CW), distributed feedback pigtailed diode laser was used as the excitation source and H2O was selected as the target analyte. Two kinds of quartz tuning forks (QTFs) with a resonant frequency (f0) of 30.72 kHz and 38 kHz were employed for the first time as an acoustic wave transducer, respectively for QEPAS instead of a standard QTF with a f0 of 32.768 kHz. The QEPAS sensor performance using the three different QTFs was experimentally investigated and theoretically analyzed. A minimum detection limit of 5.9 ppmv and 4.3 ppmv was achieved for f0 of 32.768 kHz and 30.72 kHz, respectively. PMID:25825977

  13. [Constriction of the femoral vein after McVay hernioplasty].

    PubMed

    Bjørgul, K; Forsell, C; Andersen, O K

    1994-09-10

    Constriction of the femoral vein is a well known complication to the Cooper ligament repair of inguinal hernia. This may occur as the transversalis fascia and aponeurosis are sutured to Copper's ligament, either because a suture is passed through the vein or the vein is compressed by tissue. Clinical presentation is usually signs of deep venous thrombosis or pulmonary embolism. Venography verifies the diagnosis by showing a characteristic constriction of the femoral vein. PMID:7940451

  14. Suitability of Varicose Veins for Endovenous Treatments

    Microsoft Academic Search

    S. D. Goode; G. Kuhan; N. Altaf; R. Simpson; A. Beech; T. Richards; S. T. MacSweeney; B. D. Braithwaite

    2009-01-01

    The aim of the study was to assess the suitability of radiofrequency ablation (RFA), endovenous laser ablation (EVLA), and foam sclerotherapy (FS) for patients with symptomatic varicose veins (VVs). The study comprised 403 consecutive patients with symptomatic VVs. Data on 577 legs from 403 consecutive patients with symptomatic VVs were collected for the year 2006. Median patient age was 55

  15. A secure cryptosystem from palm vein biometrics

    Microsoft Academic Search

    B. Prasanalakshmi; A. Kannammal

    2009-01-01

    This paper proposes a novel technique to generate an irrevocable cryptographic key from the biometric template. The biometric trait considered here is the palm vein. The technique proposed here utilises the minutiae features extracted from the pattern generated. The features include bifurcation points and ending points. Since other cryptographic keys are probable to theft or guess, keys generated from the

  16. Portal vein thrombosis complicating endoscopic variceal sclerotherapy

    Microsoft Academic Search

    Jacob Korula; Albert Yellin; Gary C. Kanel; Peter Nichols

    1991-01-01

    Summary Portal vein thrombosis occurred in a patient who bled from gastric varices that developed after obliteration of esophageal varices by endoscopic sclerotherapy. This complication was recognized only at surgery when thrombectomy and endovenectomy preceded the successful placement of an end-to-side portocaval shunt. At histopathology, the presence of an amorphous, eosinophilic material staining negatively for fibrin and similar to sclerosant

  17. The Aristotelian account of “heart and veins

    Microsoft Academic Search

    Mohammadali M. Shoja; R. Shane Tubbs; Marios Loukas; Mohammad R. Ardalan

    2008-01-01

    The exploration of the cardiovascular (CV) system has a history of at least five millennia. The model of the heart and veins represented by Aristotle (384–322 B.C.) is one of the earliest and accurate descriptions of the CV system. With his own specific metaphysical approach, Aristotle discussed why there might be a vascular tree composed of two vessels and also

  18. 1\\/f frequency fluctuations and nonlinearity of quartz resonators and quartz crystal oscillators

    Microsoft Academic Search

    V. N. Kuleshov; G. D. Janushevsky

    1994-01-01

    Levels of flicker fluctuations of VHF quartz crystal resonators parameters have been obtained from experimental data. For the same resonators nonlinear model characteristics have been measured. It turned out that resonators with unusual nonlinearity characteristics had very high levels of parameters fluctuations. The data reported in this paper are the result both in-bridge and in-oscillator measurements for 5th overtone AT-cut

  19. Hyperbaric Hydrothermal Atomic Force Microscope

    DOEpatents

    Knauss, Kevin G. (Livermore, CA); Boro, Carl O. (Milpitas, CA); Higgins, Steven R. (Laramie, WY); Eggleston, Carrick M. (Laramie, WY)

    2003-07-01

    A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

  20. Hyperbaric hydrothermal atomic force microscope

    DOEpatents

    Knauss, Kevin G. (Livermore, CA); Boro, Carl O. (Milpitas, CA); Higgins, Steven R. (Laramie, WY); Eggleston, Carrick M. (Laramie, WY)

    2002-01-01

    A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

  1. Magmatic-hydrothermal molybdenum isotope fractionation and its relevance to the igneous crustal signature

    NASA Astrophysics Data System (ADS)

    Greber, Nicolas D.; Pettke, Thomas; Nägler, Thomas F.

    2014-03-01

    We analysed the Mo isotope composition of a comprehensive series of molybdenite samples from the porphyry-type Questa deposit (NM, USA), as well as one rhyolite and one granite sample, directly associated with the Mo mineralization. The ?98Mo of the molybdenites ranges between - 0.48‰ and + 0.40‰, with a median at - 0.05‰. The median Mo isotope composition increases from early magmatic (- 0.29‰) to hydrothermal (- 0.05‰) breccia mineralization (median bulk breccia = - 0.17‰) to late stockwork veining (+ 0.22‰). Moreover, variations of up to 0.34‰ are found between different molybdenite crystals within an individual hand specimen. The rhyolite sample with 0.12 ?g g- 1 Mo has ?98Mo = - 0.57‰ and is lighter than all molybdenites from the Questa deposit, interpreted to represent the igneous leftover after aqueous ore fluid exsolution. We recognize three Mo isotope fractionation processes that occur between about 700 and 350 °C, affecting the Mo isotope composition of magmatic-hydrothermal molybdenites. ?1Mo: Minerals preferentially incorporate light Mo isotopes during progressive fractional crystallization in subvolcanic magma reservoirs, leaving behind a melt enriched in heavy Mo isotopes. ?2Mo: Magmatic-hydrothermal fluids preferentially incorporate heavy Mo isotopes upon fluid exsolution. ?3Mo: Light Mo isotopes get preferentially incorporated in molybdenite during crystallization from an aqueous fluid, leaving behind a hydrothermal fluid that gets heavier with progressive molybdenite crystallization. The sum of all three fractionation processes produces molybdenites that record heavier ?98Mo compositions than their source magmas. This implies that the mean ?98Mo of molybdenites published so far (~ 0.4‰) likely represents a maximum value for the Mo isotope composition of Phanerozoic igneous upper crust.

  2. Gangue mineral textures and fluid inclusion characteristics of the Santa Margarita Vein in the Guanajuato Mining District, Mexico

    NASA Astrophysics Data System (ADS)

    Moncada, Daniel; Bodnar, Robert

    2012-06-01

    Successful exploration for mineral deposits requires tools that the explorationist can use to distinguish between targets with high potential for mineralization and those with lower economic potential. In this study, we describe a technique based on gangue mineral textures and fluid inclusion characteristics that has been applied to identify an area of high potential for gold-silver mineralization in the epithermal Ag-Au deposits at Guanajuato, Mexico. The Guanajuato mining district in Mexico is one of the largest silver producing districts in the world with continuous mining activity for nearly 500 years. Previous work conducted on the Veta Madre vein system that is located in the central part of this district identified favorable areas for further exploration in the deepest levels that have been developed and explored. The resulting exploration program discovered one of the richest gold-silver veins ever found in the district. This newly discovered vein that runs parallel to the Veta Madre was named the Santa Margarita vein. Selected mineralized samples from this vein contain up to 249 g/t of Au and up to 2,280 g/t Ag. Fluid inclusions in these samples show homogenization temperatures that range from 184 to 300°C and salinities ranging from 0 to 5 wt.% NaCl. Barren samples show the same range in homogenization temperature, but salinities range only up to 3 wt.% NaCl. Evidence of boiling was observed in most of the samples based on fluid inclusions and/or quartz and calcite textures. Liquid-rich inclusions with trapped illite are closely associated with high silver grades. The presence of assemblages of vapor-rich-only fluid inclusions, indicative of intense boiling or "flashing", shows the best correlation with high gold grades.

  3. Calcified neonatal renal vein thrombosis demonstration by CT and US

    Microsoft Academic Search

    S. Jayogapal; H. L. Cohen; P. W. Brill; P. Winchester; D. Eaton

    1990-01-01

    Two cases of calcified renal vein thrombosis (RVT) were diagnosed, incidentally, within the first weeks of life. The CT images present the virtually diagnostic branching pattern of calcification that has been previously noted on pathology specimen radiographs. The CT and US images show peripheral renal vein, central renal vein and inferior vena cava calcification conforming to the two theoretical origins

  4. An update on the diagnosis and treatment of varicose veins

    Microsoft Academic Search

    Richard M. Green

    1995-01-01

    Varicose veins are a common ailment affecting more than 20 million Americans. These veins and the associated venous hypertension are associated with leg swelling, pain, dermatitis, phlebitis, and ulceration. The underlying principle of treatment of any varicosity is the removal or obliteration of pathologically functioning veins and the preservation of those with normal function. Diagnosis is obvious, but deciding whether

  5. Clinical Results of Radiofrequency Endovenous Obliteration for Varicose Veins

    Microsoft Academic Search

    Tomohiro Ogawa; Shunichi Hoshino; Hirofumi Midorikawa; Kouichi Sato

    2005-01-01

    Purpose Radiofrequency (RF) endovenous obliteration is performed in the United States and several European countries for the minimally invasive treatment of saphenous-type varicose veins. We evaluated the clinical results of RF endovenous obliteration to treat varicose veins at Fukushima Daiichi Hospital. Methods We performed endovenous obliteration of 25 great saphenous varicose veins in 20 patients, under duplex ultrasound guidance. None

  6. Subclavian vein repair in patients with an ipsilateral arteriovenous fistula.

    PubMed

    Gradman, W S; Bressman, P; Sernaque, J D

    1994-11-01

    Management of subclavian vein occlusive disease in persons with an ipsilateral arteriovenous fistula can be challenging. From July 1991 to May 1993, nine patients underwent direct exploration and repair of an obstructed subclavian vein following medial claviculectomy. Eight patients had polytetrafluoroethylene (PTFE) grafts; one patient had a Brescia-Cimino fistula. Intractable arm edema was the major symptom in five of eight. The site of the occlusive disease ranged from the midsubclavian vein to the proximal innominate vein. Pathology varied from a focal occluding web to a long segment of intimal fibroplasia. Five veins were occluded; four were stenotic. Surgical procedures consisted of endovenectomy and vein patch (four), endovenectomy and PTFE patch (one), resection of a focal stricture with end-to-end anastomosis (two), resection with PTFE interposition (one), and end-to-end internal jugular to subclavian vein transposition (one). Postoperative contrast venograms revealed a patent subclavian vein in eight of eight patients. One patient died postoperatively from unrelated causes; two patients died with a functioning fistula 8 and 12 months, respectively, after surgery. Two grafts were removed for infection and one deteriorated graft was abandoned because of repeated thrombosis. Only three of nine original grafts are currently in use, including one in which the ipsilateral subclavian vein rethrombosed. Although stent placement may now be the preferred treatment for subclavian vein stenosis, vein repair may still have a role in the treatment of subclavian vein occlusion, particularly in patients with a Brescia-Cimino fistula. PMID:7865393

  7. The 3D fault and vein architecture of strike-slip releasing- and restraining bends: Evidence from volcanic-centre-relatedmineral deposits

    USGS Publications Warehouse

    Berger, B.R.

    2007-01-01

    High-temperature, volcanic-centre-related hydrothermal systems involve large fluid-flow volumes and are observed to have high discharge rates in the order of 100-400 kg/s. The flows and discharge occur predominantly on networks of critically stressed fractures. The coupling of hydrothermal fluid flow with deformation produces the volumes of veins found in epithermal mineral deposits. Owing to this coupling, veins provide information on the fault-fracture architecture in existence at the time of mineralization. They therefore provide information on the nature of deformation within fault zones, and the relations between different fault sets. The Virginia City and Goldfield mining districts, Nevada, were localized in zones of strike-slip transtension in an Early to Mid-Miocene volcanic belt along the western margin of North America. The Camp Douglas mining area occurs within the same belt, but is localized in a zone of strike-slip transpression. The vein systems in these districts record the spatial evolution of strike-slip extensional and contractional stepovers, as well as geometry of faulting in and adjacent to points along strike-slip faults where displacement has been interrupted and transferred into releasing and restraining stepovers. ?? The Geological Society of London 2007.

  8. Host range comparison of the causal agents of pepper yellow vein and lettuce big vein

    Microsoft Academic Search

    A. Th. B. Rast

    1992-01-01

    A number of solanaceous and composite plant species were tested as hosts for the causal agents of pepper yellow vein (PYVA) and lettuce big vein (LBVA), transmitted by a pepper and a lettuce isolate ofOlpidium brassicae, respectively. The agents had the following artificial hosts in common:Lycopersicon esculentum, Solanum melongena, Physalis floridana, Nicandra physaloides, Lactuca sativa, Sonchus oleraceus andL. virosa. Capsicum

  9. Hepatocellular Carcinoma Invading the Main Portal Vein: Treatment with Transcatheter Arterial Chemoembolization and Portal Vein Stenting

    Microsoft Academic Search

    Xue-Bin Zhang; Jian-Hua Wang; Zhi-Ping Yan; Sheng Qian; Rong Liu

    2009-01-01

    To retrospectively analyze the therapeutic results of percutaneous transhepatic portal vein stenting (PTPVS) and transcatheter\\u000a arterial chemoembolization (TACE) treatment in 58 patients with hepatocellular carcinoma (HCC) invading the main portal vein\\u000a (MPV). A total of 58 procedures of PTPVS were performed, immediately after which TACE was undertaken to control HCC. The clinical\\u000a effects, complications, digital subtraction angiographic appearance, stent patency

  10. forme thorique dans le quartz et la tourmaline. Pour le quartz, l'indice ordinaire, mesur paralllement et perpendiculairement

    E-print Network

    Paris-Sud XI, Université de

    256 forme théorique dans le quartz et la tourmaline. Pour le quartz, l'indice ordinaire, mesuré la tourmaline, la variation porte sur la troisième décimale ; dans l'un et l'autre cas, elle paraît Lépinay, pour la tourmaline par ceux de Wülfing : l'un et l'autre trouvent que la loi théorique de

  11. 30 CFR 70.101 - Respirable dust standard when quartz is present.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Respirable dust standard when quartz is present. 70.101 Section 70.101 Mineral...Respirable dust standard when quartz is present. When the respirable dust...Respirable dust standard when quartz is present. (a) Each operator shall...

  12. 30 CFR 71.101 - Respirable dust standard when quartz is present.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Respirable dust standard when quartz is present. 71.101 Section 71.101 Mineral...Respirable dust standard when quartz is present. When the respirable dust...Respirable dust standard when quartz is present. (a) Each operator shall...

  13. Retinal vein-to-vein anastomoses in Sturge-Weber syndrome documented by ultra-widefield fluorescein angiography.

    PubMed

    Quan, Ann V; Moore, Grant H; Tsui, Irena

    2015-06-01

    We report the case of a 6-year-old boy with Sturge-Weber syndrome and unilateral glaucoma in his left eye. He was born with a port wine mark involving his upper left eyelid. On ultra-widefield fluorescein angiography, he was found to have several vein-to-vein anastomoses in his left retina. To our knowledge, this is the first documentation of retinal vein-to-vein anastomoses in Sturge-Weber syndrome. PMID:25944745

  14. Magmatic intrusions and hydrothermal systems on Mars

    NASA Technical Reports Server (NTRS)

    Gulick, V. C.

    1992-01-01

    We are continuing our investigation of Martian hydrothermal systems and the formation of fluvial valleys on Mars. Here we present our initial numerical modeling results of hydrothermal systems associated with magmatic intrusions on Mars. To model such hydrothermal systems, we consider single, cylindrical intrusions of 4 km height 2 km below the surface. Our preliminary results of modeling hydrothermal systems associated with magmatic intrusions in the Martian environment suggest that such systems, if associated with intrusions of several 10(exp 2) km(exp 3) or larger, in the presence of permeable, water-rich subsurface should be able to provide adequate discharges of water over the time periods needed to form fluvial valleys. However, it is important to note that the amount of water ultimately available for erosion also depends on the surface and subsurface lithology.

  15. Biomass reforming processes in hydrothermal media

    E-print Network

    Peterson, Andrew A

    2009-01-01

    While hydrothermal technologies offer distinct advantages in being able to process a wide variety of biomass feedstocks, the composition of the feedstock will have a large effect on the processing employed. This thesis ...

  16. Chemical environments of submarine hydrothermal systems

    NASA Technical Reports Server (NTRS)

    Shock, Everett L.

    1992-01-01

    Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such determinations rely on studies of pieces of deep oceanic crust uplifted by tectonic forces such as along the Southwest Indian Ridge, or more complete sections of oceanic crust called ophiolite sequences which are presently exposed on continents owing to tectonic emplacement. Much of what is thought to happen in submarine hydrothermal systems is inferred from studies of ophiolite sequences, and especially from the better-exposed ophiolites in Oman, Cyprus and North America. The focus of much that follows is on a few general features: pressure, temperature, oxidation states, fluid composition and mineral alteration, because these features will control whether organic synthesis can occur in hydrothermal systems.

  17. Rare earth element systematics in hydrothermal fluids

    Microsoft Academic Search

    Annie Michard

    1989-01-01

    Rare earth element concentrations have been measured in hydrothermal solutions from geothermal fields in Italy, Dominica, Valles Caldera, Salton Sea and the Mid-Atlantic Ridge. The measured abundances show that hydrothermal activity is not expected to affect the REE balance of either continental or oceanic rocks. The REE enrichment of the solutions increases when the pH decreases. High-temperature solutions (>230°C) percolating

  18. Sources and fractionation processes influencing the isotopic distribution of H, O and C in the Long Valley hydrothermal system, California, U.S.A.

    USGS Publications Warehouse

    White, A.F.; Peterson, M.L.; Wollenberg, H.; Flexser, S.

    1990-01-01

    The isotopic ratios of H, O and C in water within the Long Valley caldera, California reflect input from sources external to the hydrothermal reservoir. A decrease in ??D in precipitation of 0.5??? km-1, from west to east across Long Valley, is caused by the introduction of less fractionated marine moisture through a low elevation embayment in the Sierra Nevada Mountain Range. Relative to seasonal fluctuations in precipitation (-158 to -35??.), ??D ranges in hot and cold surface and groundwaters are much less variable (-135 to -105??.). Only winter and spring moisture, reflecting higher precipitation rates with lighter isotopic signatures, recharge the hydrological system. The hydrothermal fluids are mixtures of isotopically heavy recharge (??D = - 115???, ??18O = - 15???) derived from the Mammoth embayment, and isotopically lighter cold water (??D = -135???, ??18O = -18???). This cold water is not representative of current local recharge. The ??13C values for dissolved carbon in hot water are significantly heavier (- 7 to - 3???) than in cold water (-18 to -10???) denoting a separate hydrothermal origin. These ??13C values overlie the range generally attributed to magmatic degassing of CO2. However, ??13C values of metamorphosed Paleozoic basement carbonates surrounding Long Valley fall in a similar range, indicating that hydrothermal decarbonization reactions are a probable source of CO2. The ??13C and ??18O values of secondary travertime and vein calcite indicate respective fractionation with CO2 and H2O at temperatures approximating current hydrothermal conditions. ?? 1990.

  19. Towards a magmatic quartz database: tracing melt sources

    NASA Astrophysics Data System (ADS)

    Tailby, N. D.; Ackerson, M. R.; Watson, E. B.; Thomas, J. B.

    2014-12-01

    Quartz composition has seen increasing interest among the scientific community over the last decade due to new calibrations (e.g., Ti-in-quartz) and the proliferation of trace element analytical facilities. What is presently lacking in the field of quartz research is a quartz composition database. Such a single body of information can be used to evaluate whether variation seen in different crystallization environments is equally manifest in quartz composition. In this study we present >2000 new quartz analyses from >70 different granitoids and volcanic settings from around the globe (Lachlan Fold Belt, High Himalaya, French Massif, Cordilleran, Caledonian, White Mountains, Bishop, Toba, Snake River, Oman ophiolite and a number of other select locations). This dataset also combines data from a number of previous studies and together the data may collectively be used to determine which geochemical characteristics can be used to distinguish quartz from different magma types. A number of trace element concentrations or ratios (e.g., Al/Ti, Ge, Li, P and B) are notably useful when distinguishing peraluminous (e.g., cordierite-bearing granitoid) systems from more metaluminous systems (e.g., hornblende granodiorite) or plagiogranites.

  20. Deciphering the chronology of internal wedge deformation by means of strontium isotopes of vein carbonates

    NASA Astrophysics Data System (ADS)

    Berger, Alfons; Dielforder, Armin; Herwegh, Marco

    2015-04-01

    The formation and growth of accretionary complexes is accompanied by a suite of deformation processes, ranging from early compaction of unconsolidated sediments near the trench to pervasive visco-plastic deformation of well cemented rocks beyond the down-dip limit of the seismogenic zone. Although the integrated record of previous field studies, seismic surveys and borehole data provided invaluable insights into the architecture of accretionary complexes, the relative timing and precise conditions of different deformation modes have remained largely elusive. Here we present a new approach to decipher the chronology of internal wedge deformation by means of radiogenic strontium isotopes of vein carbonates. Our study area is located within the Paleogene accretionary complex of the central European Alps, comprising a ~4 km thick sequence of Upper Cretaceous to Eocene shelf sediments and syn-orogenic turbidites. We sampled different types of mineral veins that were formed during sediment compaction, nappe stacking, nappe internal thrusting, folding, layer parallel shear, normal faulting, extensional fracturing and regional out-of-sequence thrusting. We show that the 87Sr/86Sr ratio of these veins record an evolution from initially seawater derived fluids toward diagenetic-metamorphic fluids within the accretionary complex. The combination of structural analysis and Sr isotope geochemistry allows us to resolve the relative timing of different deformation events on a resolution that cannot be assessed by field observations solely. By extending the Sr-record with quartz-calcite oxygen isotope thermometry, we further constrain the temperature range of different deformation processes and demonstrate, how internal wedge deformation differs between the aseimic and seismogenic zone.

  1. Transcutaneous laser treatment of leg veins.

    PubMed

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

    2014-03-01

    Leg telangiectasias and reticular veins are a common complaint affecting more than 80% of the population to some extent. To date, the gold standard remains sclerotherapy for most patients. However, there may be some specific situations, where sclerotherapy is contraindicated such as needle phobia, allergy to certain sclerosing agents, and the presence of vessels smaller than the diameter of a 30-gauge needle (including telangiectatic matting). In these cases, transcutaneous laser therapy is a valuable alternative. Currently, different laser modalities have been proposed for the management of leg veins. The aim of this article is to present an overview of the basic principles of transcutaneous laser therapy of leg veins and to review the existing literature on this subject, including the most recent developments. The 532-nm potassium titanyl phosphate (KTP) laser, the 585-600-nm pulsed dye laser, the 755-nm alexandrite laser, various 800-983-nm diode lasers, and the 1,064-nm neodymium yttrium-aluminum-garnet (Nd:YAG) laser and various intense pulsed light sources have been investigated for this indication. The KTP and pulsed dye laser are an effective treatment option for small vessels (<1 mm). The side effect profile is usually favorable to that of longer wavelength modalities. For larger veins, the use of a longer wavelength is required. According to the scarce evidence available, the Nd:YAG laser produces better clinical results than the alexandrite and diode laser. Penetration depth is high, whereas absorption by melanin is low, making the Nd:YAG laser suitable for the treatment of larger and deeply located veins and for the treatment of patients with dark skin types. Clinical outcome of Nd:YAG laser therapy approximates that of sclerotherapy, although the latter is associated with less pain. New developments include (1) the use of a nonuniform pulse sequence or a dual-wavelength modality, inducing methemoglobin formation and enhancing the optical absorption properties of the target structure, (2) pulse stacking and multiple pass laser treatment, (3) combination of laser therapy with sclerotherapy or radiofrequency, and (4) indocyanin green enhanced laser therapy. Future studies will have to confirm the role of these developments in the treatment of leg veins. The literature still lacks double-blind controlled clinical trials comparing the different laser modalities with each other and with sclerotherapy. Such trials should be the focus of future research. PMID:24220848

  2. Volcanic Controls on Alteration at the PACMANUS hydrothermal System (Papua New Guinea, ODP leg 193)

    NASA Astrophysics Data System (ADS)

    Paulick, H.; Herzig, P.

    2003-04-01

    The PACMANUS hydrothermal system in the Manus back-arc basin is located at a water depth of 1700 m on the crest of a dacite volcanic ridge. The Ocean Drilling Program Leg 193 focused on two active discharge sites reaching a maximum depth of 380 m below seafloor. Fluid-dacite interaction generated secondary mineral assemblages including argillaceous (chl-qtz) alteration and acid sulfate (qtz-ill-pyro-anhy) alteration [1, 2]. Pervasive and fracture-controlled fluid flow and overprinting alteration stages induced substantial textural modifications such as apparent clastic texture in coherent dacite facies [3]. The mass changes of various volcanic facies (coherent: vesicular, perlitic, spherulitic; volcanic breccia) and handspecimen scale heterogeneities (apparently clastic, hydrothermal stockworks; clasts vs matrix) were quantified using immobile elements (Ti, Zr) and a multiple-precursor model. In general, Na and Ca have been lost as a result of plag destruction and Fe, Mg, H20, S, SO4 and K have been gained (formation of chl, py, anhy, ill, K-fsp). In coherent facies an overall mass gain is ubiquitous and generally associated with Si addition. In contrast, clasts in volcanic breccias have lost substantial Si and total mass whereas the respective matrix separates show mass gains in the form of Si, Fe, Mg, H2O and S. Similarly, apparent volcanic clasts in intensely veined or stockworked facies is mass-depleted whereas the respective bulk rock samples (volcanic + vein material) show mass gains (Si, Fe, Mg, S addition). These data indicate that fluid-dacite interaction at PACMANUS was a complex and multi-stage process. Fluid flow in intra-clast space of volcanic breccia and in fractured coherent facies may have been associated with substantial mass extraction from the surrounding volcanic material. [1] Binns, R.A., Barriga, F.J.A.S., Miller, D.J., et al. (2002): Proceedings of the ODP, Initial Report Leg 193 [CD-ROM]. Texas A&M University, USA. [2] Paulick, H., Vanko, D.A., Yeats, C.J. (in review): Drill core-based facies reconstruction of a deep-marine, felsic volcano hosting an active hydrothermal system (Pual Ridge, PNG, ODP Leg 193), J. Volc. and Geotherm. Res. [3] Bach, W. and 6 others (in press): Controls of fluid chemistry and complexation on rare-earth element contents of anhydrite from the Pacmanus subseafloor hydrothermal system, Manus Basin, Papua New Guinea, Miner Deposita

  3. New multiphase equation of state for polycrystalline quartz

    SciTech Connect

    Boettger, J.C.; Lyon, S.P.

    1990-10-01

    We have generated separate equations of state (EOS's) for the alpha quartz, coesite, and stishovite phases of polycrystalline quartz (SiO{sub 2}) using the computer program GRIZZLY. We also modified the program GRIZZLY to combine two single-phase EOS's for a given material into a single two-phase EOS via minimization of the Gibbs free energy. This new version of GRIZZLY has been used to generate a three-phase SESAME type EOS for polycrystalline quartz using the three EOS's mentioned above. All four of the EOS's produced for SiO{sub 2} are now available on request. 17 refs., 4 figs., 1 tab.

  4. Solid phase epitaxial regrowth of ion beam-amorphized ?-quartz

    NASA Astrophysics Data System (ADS)

    Roccaforte, F.; Bolse, W.; Lieb, K. P.

    1998-09-01

    Solid phase epitaxial growth of ion beam-amorphized ?-quartz has been studied by means of Rutherford backscattering spectrometry in channeling geometry. ?-quartz single crystals were irradiated with Cs+ and Xe+ ions and annealed in air or in vacuum at 500-900 °C. Complete epitaxial regrowth has been observed in the Cs-irradiated samples, after 875 °C annealing in air. On the other hand, vacuum annealing provided only incomplete regrowth of the amorphous layer, while Xe-irradiated ?-quartz could not be regrown up to 900 °C. The behavior of Cs in the recrystallization process is discussed in terms of the SiO2-network topology.

  5. Hydrogen diffusion in quartz: A molecular dynamics investigation

    SciTech Connect

    Bongiorno, A.; Colombo, L. [Univ. di Milano (Italy)

    1996-12-31

    The authors present a molecular dynamics investigation on hydrogen diffusivity in crystalline quartz by computing the diffusion coefficient over a wide range of temperatures (700K < T < 1,500 K) and by characterizing the diffusion path and mechanism. The main findings are: (1) hydrogen diffusion is anisotropically confined along the c-axis in {alpha}- and {beta}-quartz; (2) hydrogen diffuses through a jump-like mechanism; (3) the temperature-dependent diffusivity follows an Arrhenius law with activation energy of 0.56 eV and 0.27 eV for {alpha}- and {beta}-quartz, respectively.

  6. Fiber optic pressure sensor based on quartz force transducers

    NASA Astrophysics Data System (ADS)

    Bigelow, Russell N.; Sadler, James M.; Stapleton, Terry M.; Sun, Mei H.; Wickersheim, Kenneth A.; Ingold, Joseph P.

    1993-03-01

    A fiber optic pressure sensor is being developed for the Naval Surface Warfare Center- Dahlgren Division for use in measuring the pressure within sonar domes of Naval ships. The sensor comprises a quartz crystal tuning fork and force transduction mechanism such that the frequency of the quartz crystal is proportional to pressure within the sonar dome. An optical fiber interface is used to transport light to power the quartz crystal and measure its frequency. These sensors are compatible with the fiber optic cable plant of Naval ships.

  7. Sticky quartz crystal microbalance as a particle monitor

    NASA Astrophysics Data System (ADS)

    Uy, O. Manuel; Cain, Russell P.; Carkhuff, Bliss G.; Lennon, Andrew M.

    1999-10-01

    Quartz crystal microbalances (QCM) have been used for over twenty years as contamination monitors in space satellites to measure film deposition on sensitive surfaces such optical mirrors, thermal radiators and solar arrays. However, it is only recently that miniature quartz crystal microbalances were used as particle monitors after the QCMs were coated with low outgassing grease to trap and measure the mass of particles impinging on the quartz surfaces. Results of these experiments utilizing 'sticky' QCMs are described for a series of wind- tunnel missile tests.

  8. Study of hydrothermal channels based on near-bottom magnetic prospecting: Application to Longqi hydrothermal area

    NASA Astrophysics Data System (ADS)

    Tao, W.; Tao, C.; Li, H.; Zhaocai, W.; Jinhui, Z.; Qinzhu, C.; Shili, L.

    2014-12-01

    Mid-ocean ridges, largely present far from the continental plates, are characterized by complex geological structures and numerous hydrothermal systems with complex controlling factors. Exploring seafloor sulfide resources for industrial and scientific applications is a challenge. With the advent of geophysical surveys for seabed investigation, near-bottom magnetic prospecting, which yields shallow geological structure, is an efficient method for investigating active and inactive hydrothermal fields and for researching the structure of hydrothermal systems (Tivey et al., 1993, 1996?German et al., 2008). We collected near-bottom magnetic data in the Longqi hydrothermal area, located in the southwest Indian ridge (49.6° E; Zhu et al., 2010; Tao et al., 2014), using the autonomous benthic explorer, an autonomous underwater vehicle, during the second leg of the Chinese cruise DY115-19 on board R/V DaYangYiHao. Based on the results of the intensity of the spatial differential vector method (Seaman et al., 1993), we outline the hydrothermal alternation zone. By building models, we subsequently infer a fault along the discovered hydrothermal vents; this fault line may be connected to a detachment fault (Zhao et al., 2013). In addition, we discuss the channels of the hydrothermal circulation system (Figure 1), and presume that heat was conducted to the sea subsurface by the detachment fault; the aqueous fluid that infiltrated the fault is heated and conveyed to the seafloor, promoting the circulation of the hydrothermal system.

  9. Retrospective Comparison of Clinical Outcomes between Endovenous Laser and Saphenous Vein-sparing Surgery for Treatment of Varicose Veins

    Microsoft Academic Search

    Chih-Yang Chan; Tzu-Chun Chen; Yung-Kun Hsieh; Jih-Hsin Huang

    Background  The purpose of the present study was to compare management of varicose veins by endovenous laser ablation (EVL) and a vein-sparing\\u000a procedure (CHIVA: Conservatrice et Hémodynamique de l’Insuffisance Veineuse en Ambulatoire) for management of varicose veins.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Data from 82 consecutive patients with great saphenous vein (GSV) reflux and primary varicose veins presenting to the vascular\\u000a clinic at the Far Eastern

  10. Ion-beam damage to quartz crystals

    NASA Astrophysics Data System (ADS)

    Macaulay-Newcombe, R. G.; Thompson, D. A.; Davies, J. A.; Stevanovic, D. V.

    1990-02-01

    Heavy-ion damage was produced in ?-quartz (single-crystal SiO 2) by bombarding with 4'He + to Bi + in the energy range of 15-200 keV, at both 300 K and ? 50 K. The samples were analysed in situ with Rutherford backscattering/channeling. using 1-2 MeV 4He + ions; data were obtained from both the oxygen and silicon peaks, so that damage stoichiometry could be calculated. At low ion fluences (˜ 10 10 - 10 101 ions/mm 2) the apparent damage level increases linearly with fluence. but at rates of about 3-19 times greater than predicted by the modified Kinchin-Pease equation [1]. At higher fluences (˜ 10 11 - 10 12 ions/mm 2) the rate of damage increases with fluence for elastic energy deposition rates of less than ˜ 0.08 eV/atom, but remains constant for greater elastic energy deposition rates. At even higher ion fluences saturation of the damage occurs. It has been observed that the analysis beam creates damage at a rate dependent on the level of damage already present in the crystal: furthermore, the damage created hy the analysis ions appears to be predominantly due to the inelastically deposited energy. Strain effects seem to greatly exaggerate the level of damage indicated by simple channeling calculations [2]. A rough model is proposed to explain both the high rates of damage production and the nonstoichiometry of the damage.

  11. Patterning of Leaf Vein Networks by Convergent Auxin Transport Pathways

    PubMed Central

    Sawchuk, Megan G.; Edgar, Alexander; Scarpella, Enrico

    2013-01-01

    The formation of leaf vein patterns has fascinated biologists for centuries. Transport of the plant signal auxin has long been implicated in vein patterning, but molecular details have remained unclear. Varied evidence suggests a central role for the plasma-membrane (PM)-localized PIN-FORMED1 (PIN1) intercellular auxin transporter of Arabidopsis thaliana in auxin-transport-dependent vein patterning. However, in contrast to the severe vein-pattern defects induced by auxin transport inhibitors, pin1 mutant leaves have only mild vein-pattern defects. These defects have been interpreted as evidence of redundancy between PIN1 and the other four PM-localized PIN proteins in vein patterning, redundancy that underlies many developmental processes. By contrast, we show here that vein patterning in the Arabidopsis leaf is controlled by two distinct and convergent auxin-transport pathways: intercellular auxin transport mediated by PM-localized PIN1 and intracellular auxin transport mediated by the evolutionarily older, endoplasmic-reticulum-localized PIN6, PIN8, and PIN5. PIN6 and PIN8 are expressed, as PIN1 and PIN5, at sites of vein formation. pin6 synthetically enhances pin1 vein-pattern defects, and pin8 quantitatively enhances pin1pin6 vein-pattern defects. Function of PIN6 is necessary, redundantly with that of PIN8, and sufficient to control auxin response levels, PIN1 expression, and vein network formation; and the vein pattern defects induced by ectopic PIN6 expression are mimicked by ectopic PIN8 expression. Finally, vein patterning functions of PIN6 and PIN8 are antagonized by PIN5 function. Our data define a new level of control of vein patterning, one with repercussions on other patterning processes in the plant, and suggest a mechanism to select cell files specialized for vascular function that predates evolution of PM-localized PIN proteins. PMID:23437008

  12. Inadvertent Port: Catheter Placement in Azygos Vein

    PubMed Central

    Harish, K.; Madhu, Y. C.

    2012-01-01

    Totally implantable ports are safe and effective means of venous access for administration of chemotherapy. One of the usual vessels accessed, through which the port is placed, is the subclavian. Herein, we report a case where the central access was obtained through the left subclavian vein. But the catheter when it was placed was found to be in the azygos vein. This was confirmed with dye study. This is the first report of such an occurrence with subclavian access. The catheter was later withdrawn and repositioned in the superior vena cava. We recommend that the entire procedure of catheter placement must be done under fluoroscopy guidance to ensure safe and error-free positioning. PMID:23730139

  13. Finger Vein Recognition with Personalized Feature Selection

    PubMed Central

    Xi, Xiaoming; Yang, Gongping; Yin, Yilong; Meng, Xianjing

    2013-01-01

    Finger veins are a promising biometric pattern for personalized identification in terms of their advantages over existing biometrics. Based on the spatial pyramid representation and the combination of more effective information such as gray, texture and shape, this paper proposes a simple but powerful feature, called Pyramid Histograms of Gray, Texture and Orientation Gradients (PHGTOG). For a finger vein image, PHGTOG can reflect the global spatial layout and local details of gray, texture and shape. To further improve the recognition performance and reduce the computational complexity, we select a personalized subset of features from PHGTOG for each subject by using the sparse weight vector, which is trained by using LASSO and called PFS-PHGTOG. We conduct extensive experiments to demonstrate the promise of the PHGTOG and PFS-PHGTOG, experimental results on our databases show that PHGTOG outperforms the other existing features. Moreover, PFS-PHGTOG can further boost the performance in comparison with PHGTOG. PMID:23974154

  14. Effects of glacial ice on subsurface temperatures of hydrothermal systems in Yellowstone National Park, Wyoming: Fluid-inclusion evidence

    SciTech Connect

    Bargar, K.E.; Fournier, R.O. (Geological Survey, Menlo Park, CA (USA))

    1988-12-01

    Hydrothermal quartz and fluorite crystals containing liquid-rich fluid inclusions (coexisting vapor-rich fluid inclusions were not observed) were found in drill cores from eight relatively shallow research holes drilled by the US Geological Survey in and near major geyser basins of Yellowstone National Park. Homogenization temperatures (T{sub h}) for mostly secondary fluid inclusions show variations in temperature that have occurred at give depths since precipitation of the host minerals. Within major hydrothermal upflow zones, fluid-inclusion T{sub h} values all were found to be equal to or higher (commonly 20-50 C and up to 155 C higher) than present temperatures at the depths sampled. During periods when thick glacial ice covered the Yellowstone National Park region, pore-fluid pressures in the underlying rock were increased in proportion to the weight of the overlying column of ice. Accordingly, theoretical reference boiling-point curves that reflect the maximum temperature attainable in a hot-water geothermal system at a given depth were elevated, and temperatures within zones of major hydrothermal upflow (drill holes Y-2, Y-3, Y-6, Y-11, Y-13, and upper part of Y-5) increased. The thicknesses of ice required to elevate boiling-point curves sufficiently to account for the observed fluid-inclusion T{sub h} values are within the ranges estimated by glacial geologic studies. At the margins of major hydrothermal upflow zones (drill holes Y-4 and Y-9), fluid-inclusion T{sub h} values at given depths range from 57 C lower to about the same as the current temperature measurements because of a previous decrease in the rate of discharge of warm water and/or an increase in the rate of recharge of cold water into the hydrothermal system.

  15. Suitability of Varicose Veins for Endovenous Treatments

    Microsoft Academic Search

    S. D. Goode; G. Kuhan; N. Altaf; R. Simpson; A. Beech; T. Richards; S. T. MacSweeney; B. D. Braithwaite

    2009-01-01

    The aim of the study was to assess the suitability of radiofrequency ablation (RFA), endovenous laser ablation (EVLA), and\\u000a foam sclerotherapy (FS) for patients with symptomatic varicose veins (VVs). The study comprised 403 consecutive patients with\\u000a symptomatic VVs. Data on 577 legs from 403 consecutive patients with symptomatic VVs were collected for the year 2006. Median\\u000a patient age was 55 years

  16. Hydrothermal Alteration Minerals of the Geysers Steam Field, California and their Potential Use in Exploration

    SciTech Connect

    Moore, Diane

    1980-12-16

    Little information has been published on the hydrothermal alteration minerals occurring at depth in the Geysers steam field, California. Steiner (1958) reported the occurrence of wairakite from a well; McNitt (1964) identified pyrite, sericite, calcite, quartz, siderite, apatite and chlorite in cores of Franciscan graywacke and greenstone. Recently, Union Oil Geothermal Division furnished a set of well cores from the cap rock overlying the steam reservoir for geophysical studies (Lockner -e t -a l . , 1980). Cores of metagraywacke and greenstone from 4 wells were compared to unaltered Franciscan metagraywacke from surface exposures. Several previously unreported alteration minerals were found in the cored rocks, including epidote, tremolite-actinolite, prehnite and tourmaline. This note describes the observed alteration minerals and some of the factors that controlled their growth.

  17. Nitroxidergic nerve stimulation relaxes human uterine vein.

    PubMed

    Toda, N; Kimura, T; Okamura, T

    1995-11-01

    The predominant action of nitroglycerin, a nitric oxide (NO) donor, on veins over arterioles is well recognized. This study was carried out to determine whether endogenous NO derived from vasodilator nerve regulates the tone of human uterine venous strips. The isolated vein partially contracted with prostaglandin F2 alpha responded to nicotine with a contraction or a relaxation; the contraction was reversed to a relaxation by prazosin, and the relaxation was potentiated by the alpha 1-adrenoceptor antagonist. In prazosin-treated strips, nicotine-induced relaxations were not affected by timolol, atropine and indomethacin but were abolished by oxyhemoglobin and NG-nitro-L-arginine (L-NA), a NO synthase inhibitor. The D-enantiomer was without effect. The inhibition by L-NA was reversed by L-arginine. The NO-induced relaxation was not influenced by L-NA but was abolished by oxyhemoglobin. It may be concluded that the human uterine vein is innervated by vasodilator nerves from which NO is liberated as a vasodilator neurotransmitter. Norepinephrine from adrenergic nerves contracts venous smooth muscle possibly via stimulation of alpha 1-adrenoceptors. PMID:8801269

  18. Reconstructing Magmatic-Hydrothermal Systems via Geologic Mapping of the Tilted, Cross-sectional Exposures of the Yerington District, Nevada

    NASA Astrophysics Data System (ADS)

    Dilles, J. H.; Proffett, J. M.

    2011-12-01

    The Jurassic Yerington batholith was cut by Miocene to recent normal faults and tilted ~90° west (Proffett, 1977). Exposures range from the volcanic environment to ~6 km depth in the batholith. Magmatic-hydrothermal fluids derived from the Luhr Hill granite and associated porphyry dikes produced characteristic porphyry copper mineralization and rock alteration (K-silicate, sericitic, and advanced argillic) in near-vertical columnar zones above cupolas on the deep granite. In addition, saline brines derived from the early Mesozoic volcanic and sedimentary section intruded by the batholith were heated and circulated through the batholith producing voluminous sodic-calcic and propylitic alteration. The magnetite-copper ore body at Pumpkin Hollow is hosted in early Mesozoic sedimentary rocks in the contact aureole of the batholith, and appears to be an IOCG type deposit produced where the sedimentary brines exited the batholith. Although many advances in understanding of Yerington have been made by lab-based geochronology and geochemistry studies, the first order igneous and hydrothermal features were recognized first in the 1960s and 1970s and are best documented by geological mapping at a variety of scales ranging from 1:500 to 1:24,000. The Anaconda technique of mapping mine benches, trenches, and drill cores was perfected here (Einaudi, 1997), and other techniques were used for surface exposures. The geologic and hydrothermal alteration maps establish that hydrothermal alteration accompanied each of several porphyry dike intrusions, and affected more than 100 km3 of rock. Both zonation in alteration mineralogy and vein orientations allow reconstruction of source areas and >5 km-long flow-paths of hydrothermal fluids through the batholith and contact aureole.

  19. Mineral associations produced by sodic-calcic hydrothermal alteration in the Buffalo Mountain pluton, north-central Nevada

    SciTech Connect

    McBride, D. (Georgia Southern Univ., Statesboro, GA (United States). Dept. of Geology and Geography)

    1993-03-01

    Sodic-calcic (Na-Ca) hydrothermal alteration is prevalent throughout Mesozoic-age arc igneous rocks in the western US. The middle Jurassic Buffalo Mountain pluton, located in north-central Nevada, contains particularly well developed Na-Ca metasomatism. The Buffalo Mountain pluton is composed of porphyritic syenite, quartz monzonite, small bordering stocks (which account for less than 1% of the pluton), and an extensive felsic dike swarm. Quartz monzonite intruded syenite and constitutes the majority of the surface area. Unaltered porphyritic syenite is composed of perthite, plagioclase, quartz, augite, hornblende, biotite, olivine, magnetite, and other minerals accounting for less than 1% of the rock. Unaltered quartz monzonite is an aggregate of K-feldspar, plagioclase, quartz, biotite, hornblende, and accessory minerals accounting for less than 1% of the rock. The dikes cut both phases of the total intrusive rock body and are closely related in space to zones of Na-Ca alteration. Alteration variably affects all igneous rock types and exists as both fracture-controlled and pervasive Na-Ca alteration. Sodic-calcic alteration resulted in the following mineral reactions: K-feldspar is replaced by chalky-colored plagioclase, and primary mafic minerals react to form pale green diopside or, less commonly, actinolite. Garnet, scapolite, and epidote are often spatially associated with Na-Ca altered rocks. The fact that Na-Ca alteration occurs most commonly in and around dikes suggests that they might have been the source of channel for fluid entry into the surrounding igneous rocks. Further study will seek to constrain the origins and pathways of Na-Ca fluids.

  20. APPLICATIONS OF CATHODOLUMINESCENCE OF QUARTZ AND FELDSPAR TO SEDIMENTARY PETROLOGY.

    USGS Publications Warehouse

    Ruppert, Leslie F.

    1987-01-01

    Cathodoluminescence (CL), the emission of visible light during electron bombardment, was first used in sandstone petrology in the mid-1960's. CL techniques are especially useful for determining the origin and source of quartz and feldspar, two of the most common constituents in clastic rocks. CL properties of both minerals are dependent on their temperature of crystallization, duration of cooling, and/or history of deformation. Detrital quartz and feldspar are typically derived from igneous and metamorphic sources and luminesce in the visible range whereas authigenic quartz and feldspar form at low temperatures and do not luminesce. Quantification of luminescent and non-luminescent quartz and feldspar with the scanning electron microscope, electron microprobe, or a commercial CL device can allow for the determination of origin, diagenesis, and source of clastic rocks when used in conjunction with field and other petrographic analyses.

  1. Effects of Grain Size and Sorting on Quartz Cementation and Pore Space Evolution

    NASA Astrophysics Data System (ADS)

    Williams, R.; Farver, J. R.; Onasch, C.

    2012-12-01

    The effect of grain size and sorting on the rate of quartz cementation and corresponding pore space evolution in sandstones has been experimentally investigated under static hydrothermal conditions. Charges consisted of two different grain size fractions of disaggregated St. Peter sandstone grains separated by a layer of amorphous SiO2 which served as a source for dissolved SiO2. Au tubes were loaded with approximately 150 mg of either coarse (425-500 ?m) or fine grained (90-125 ?m) St. Peter sand, followed by approximately 40 mg NaCl brine (25 wt. % NaCl) to increase the silica solubility and to better mimic oil field brines, 20 mg amorphous SiO2, 10 mg AlCl3 (a luminescent tracer), an additional 20 mg amorphous SiO2, and finally approximately 150 mg of sand of the remaining size fraction. The charges were weld-sealed and run in cold-seal pressure vessels at 300°C to 450°C at 150 MPa confining pressure for up to 8 weeks. This novel configuration allows for direct comparison of cementation processes in different grain size fractions by ensuring that chemical and physical conditions are identical in each. The nature and amount of quartz cement in the samples were determined by a combination of CL, light microscopy, and scanning electron microscopy. Additionally, numeric models were constructed for comparison with experimental results. The results indicate that the amount and distribution of new quartz cement is a function of systematic variations in surface area normalized (SAN) rate, diffusion controlled SiO2 supersaturation, grain size, and fracture density. Cementation followed a common pattern in all samples. Microfractures, which formed during pressurization of the charges, sealed very rapidly and were followed by overgrowth formation on the quartz grains. Cementation began closest to the amorphous silica, before progressing away to more distal portions of the charge. Measured SAN rates are shown to decrease in a manner consistent with that proposed by Lander et al. (2008), wherein decreases in rate are more pronounced in relatively fine grain size fractions. Back-calculations of apparent SAN rate for discrete sections of each experiment show that peak rates are experienced following the modeled onset of SiO2 supersaturation. The observed temporal sequence of cementation in conjunction with modeling efforts of SiO2 supersaturation shows that the rate limiting factor in quartz cementation may vary between transport and precipitation in areas of sufficient fracture density. In addition, pore space analysis of both experimental and modeled results indicates that while all grain size fractions rapidly converge on similar total porosity values the 2D connectivity of porosity varies markedly as a function of grain size and sorting. This result suggests that previous efforts to tie specific hydrological or mechanical effects to total porosity in sandstones may provide limited predictive capability by not considering the effect of grain size and sorting during progressive diagenesis.

  2. Two modified smoky quartz centers in natural citrine

    Microsoft Academic Search

    D. Maschmeyer; K. Niemann; H. Hake; G. Lehmann; A. Räuber

    1980-01-01

    Electron paramagnetic resonance (EPR) measurements on natural citrine and greenish-yellow quartz revealed the presence of several localized hole centers adjacent to an aluminium impurity. The g tensors and their principal axes directions were determined for the two most prominent centers. The g-tensor variations and 27Al hyperfine splittings are roughly half as large as for the well-known smoky quartz centers. Optical

  3. A Triple-Quartz-Plate Supersonic Generating and Receiving System

    Microsoft Academic Search

    Henry L. Yeagley

    1935-01-01

    This treatise is an exposition of the measurement of high frequency sound by means of an originally designed and constructed apparatus, together with results obtained and the interpretation thereof. The apparatus consists of a high precision, supersonic, sending and receiving system of a triple-quartz-plate type. Two of the piezo-quartz plates used act as supersonic transducers to transform electromagnetic energy into

  4. On the pleochroism of amethyst quartz and its absorption spectra

    Microsoft Academic Search

    S. Pancharatnam

    1954-01-01

    9. Summary  Amethyst is optically biaxial, and does not conform to the trigonal symmetry of colourless quartz, though thec-axis appears as the acute bisectrix in its biaxial figure. The pleochroic and biaxial properties taken together conform only\\u000a to a symmetry of the monoclinic class, the axis of symmetry being coincident with one of the electrical axes of the colourless\\u000a quartz in

  5. Wear performance of ultrahigh molecular weight polyethylene\\/quartz composites

    Microsoft Academic Search

    X. L. Xie; C. Y. Tang; Kathy Y. Y. Chan; X. C. Wu; C. P. Tsui; C. Y. Cheung

    2003-01-01

    Ultrahigh molecular weight polyethylene (UHMWPE)\\/quartz composites were compression molded in the presence of organosiloxane, and then hydrolyzed. The used organosiloxane is vinyl tri-ethyloxyl silane. The gelation, the melting behavior, the crystallinity, the mechanical properties and the wear resistance of UHMWPE\\/quartz composites were investigated. The results showed that organosiloxane can act as a cross-linking agent for UHMWPE matrix and serve as

  6. New multiphase equation of state for polycrystalline quartz

    Microsoft Academic Search

    J. C. Boettger; S. P. Lyon

    1990-01-01

    We have generated separate equations of state (EOS's) for the alpha quartz, coesite, and stishovite phases of polycrystalline quartz (SiOâ) using the computer program GRIZZLY. We also modified the program GRIZZLY to combine two single-phase EOS's for a given material into a single two-phase EOS via minimization of the Gibbs free energy. This new version of GRIZZLY has been used

  7. Surface adsorption of Cs137 ions on quartz crystals

    USGS Publications Warehouse

    Antkiw, Stephen; Waesche, H.; Senftle, F.

    1954-01-01

    Adsorption tests were made on four large synthetic and three natural quartz crystals to see if surface defects might be detected by subsequent autoradiography techniques. The adsorbent used was radioactive Cs137 in a solution of Cs 137Cl. Natural quartz crystals adsorbed more cesium than the synthetic crystals. Certain surface defects were made evident by this method, but twinning features could not be detected.

  8. Review of Quartz Analytical Methodologies: Present and Future Needs

    Microsoft Academic Search

    Floyd A. Madsen; Mike C. Rose; Rick Cee

    1995-01-01

    A review of analytical methods for the qualitative and quantitative determination of crystalline silica is presented. The three prevalent forms of crystalline silica—quartz, cristobalite, and tridymite—are alluded to. Performance and popularity of present quartz analytical methods such as X-ray diffraction (XRD), infrared (IR) spectroscopy, and colorimetry are illustrated using Proficiency Analytical Testing (PAT) Program data. Although substantial improvements in performance

  9. Variations of Gonadal Veins: Embryological Prospective and Clinical Significance

    PubMed Central

    Gupta, Raman; Aggarwal, Navita

    2015-01-01

    Introduction: An adequate knowledge of anomalies of gonadal veins will help the radiologists and surgeons in recognition and protection of these veins which play major roles in thermo-regulation that is essential for the efficient functioning of testis on which the survival of the human species depends. Aim: The aim of this work is to present an analysis of the anatomical variations of gonadal veins. An effort has also been made to explicate the possible embryological model of development of such variants and to present the variable clinical aspects concerning them. Materials and Methods: Gonadal veins in 60 dissection room cadavers were examined for variations from the classic anatomic description. Result: In the present study, out of 60 cases, male: female ratio was 2:1(40:20) in which no variation was found in ovarian veins. In the 18 (45%) cases, testicular veins showed variations which consist of duplication and atypical drainage. Discussion: Variations of drainage of gonadal vein are due to error of embryological development in venous shift and alteration in anastomotic channel of post-cardinal, supra-cardinal and sub cardinal veins. Conclusion: The gonadal veins present numeric variations as well as variations in its site of drainage, which attributed to the various pathological conditions as varicocele and pelvic congestion syndrome, leading to infertility in patients. Hence, in -depth knowledge of these developmental anomalies of gonadal veins is important. PMID:25859438

  10. Development of HIFU Therapy System for Lower Extremity Varicose Veins

    SciTech Connect

    Ota, Ryuhei; Yoshinaka, Kiyoshi; Takagi, Shu; Matsumoto, Yoichiro [Department of Mechanical Engineering, University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Suzuki, Jun; Deguchi, Juno; Miyata, Tetsuro [Vascular Surgery, Department of Surgery, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2009-04-14

    High-intensity focused ultrasound (HIFU) treatment utilizing microbubbles was investigated in the present study. It is known that microbubbles have the potential to enhance the heating effects of an ultrasound field. In this study, the heat accompanying microbubble oscillation was used to occlude varicose veins. Alteration of veins was observed after ultrasound irradiation. Veins were resected by stripping. In this study, two vein conditions were adopted during HIFU irradiation; non-compressed and compressed. Compressing the vein was expected to improve occlusion by rubbing the altered intima under compressed conditions. The frequency of the ultrasound was 1.7 MHz, the intensity at the focus was 2800 W/cm{sup 2}, and the irradiation time was 20 s. In this study, the contrast agent Levovist registered was chosen as a microbubble source, and the void fraction (ratio of total gas volume to liquid) in the vein was fixed at 10{sup -5}. Under non-compressed conditions, changes were observed only at the adventitia of the vein anterior wall. In contrast, under compressed conditions, changes were observed from the intima to the adventitia of both the anterior and posterior walls, and they were partly stuck together. In addition, more experiments with hematoxylin-eosin staining suggested that the changes in the vein were more substantial under the latter conditions. From these results, it was confirmed that the vein was occluded more easily with vein compression.

  11. Atomistic molecular dynamics simulations of shock compressed quartz.

    PubMed

    Farrow, M R; Probert, M I J

    2011-07-28

    Atomistic non-equilibrium molecular dynamics simulations of shock wave compression of quartz have been performed using the so-called BKS semi-empirical potential of van Beest, Kramer, and van Santen [Phys. Rev. B 43, 5068 (1991)] to construct the Hugoniot of quartz. Our scheme mimics the real world experimental set up by using a flyer-plate impactor to initiate the shock wave and is the first shock wave simulation that uses a geometry optimised system of a polar slab in a three-dimensional system employing periodic boundary conditions. Our scheme also includes the relaxation of the surface dipole in the polar quartz slab which is an essential pre-requisite to a stable simulation. The original BKS potential is unsuited to shock wave calculations and so we propose a simple modification. With this modification, we find that our calculated Hugoniot is in good agreement with experimental shock wave data up to 25 GPa, but significantly diverges beyond this point. We conclude that our modified BKS potential is suitable for quartz under representative pressure conditions of the Earth core, but unsuitable for high-pressure shock wave simulations. We also find that the BKS potential incorrectly prefers the ?-quartz phase over the ?-quartz phase at zero-temperature, and that there is a ? ? ? phase-transition at 6 GPa. PMID:21806139

  12. Ancient Hydrothermal Springs in Arabia Terra, Mars

    NASA Technical Reports Server (NTRS)

    Oehler, Dorothy Z.; Allen, Carlton C.

    2008-01-01

    Hydrothermal springs are important astrobiological sites for several reasons: 1) On Earth, molecular phylogeny suggests that many of the most primitive organisms are hyperthermophiles, implying that life on this planet may have arisen in hydrothermal settings; 2) on Mars, similar settings would have supplied energy- and nutrient-rich waters in which early martian life may have evolved; 3) such regions on Mars would have constituted oases of continued habitability providing warm, liquid water to primitive life forms as the planet became colder and drier; and 4) mineralization associated with hydrothermal settings could have preserved biosignatures from those martian life forms. Accordingly, if life ever developed on Mars, then hydrothermal spring deposits would be excellent localities in which to search for morphological or chemical remnants of that life. Previous attempts to identify martian spring deposits from orbit have been general or limited by resolution of available data. However, new satellite imagery from HiRISE has a resolution of 28 cm/pixel which allows detailed analysis of geologic structure and geomorphology. Based on these new data, we report several features in Vernal Crater, Arabia Terra that we interpret as ancient hydrothermal springs.

  13. Peptide synthesis in early Earth hydrothermal systems.

    PubMed

    Lemke, Kono H; Rosenbauer, Robert J; Bird, Dennis K

    2009-03-01

    We report here results from experiments and thermodynamic calculations that demonstrate a rapid, temperature-enhanced synthesis of oligopeptides from the condensation of aqueous glycine. Experiments were conducted in custom-made hydrothermal reactors, and organic compounds were characterized with ultraviolet-visible procedures. A comparison of peptide yields at 260 degrees C with those obtained at more moderate temperatures (160 degrees C) gives evidence of a significant (13 kJ . mol(-1)) exergonic shift. In contrast to previous hydrothermal studies, we demonstrate that peptide synthesis is favored in hydrothermal fluids and that rates of peptide hydrolysis are controlled by the stability of the parent amino acid, with a critical dependence on reactor surface composition. From our study, we predict that rapid recycling of product peptides from cool into near-supercritical fluids in mid-ocean ridge hydrothermal systems will enhance peptide chain elongation. It is anticipated that the abundant hydrothermal systems on early Earth could have provided a substantial source of biomolecules required for the origin of life. PMID:19371157

  14. Sample Return from Ancient Hydrothermal Springs

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dorothy Z.

    2008-01-01

    Hydrothermal spring deposits on Mars would make excellent candidates for sample return. Molecular phylogeny suggests that that life on Earth may have arisen in hydrothermal settings [1-3], and on Mars, such settings not only would have supplied energy-rich waters in which martian life may have evolved [4-7] but also would have provided warm, liquid water to martian life forms as the climate became colder and drier [8]. Since silica, sulfates, and clays associated with hydrothermal settings are known to preserve geochemical and morphological remains of ancient terrestrial life [9-11], such settings on Mars might similarly preserve evidence of martian life. Finally, because formation of hydrothermal springs includes surface and subsurface processes, martian spring deposits would offer the potential to assess astrobiological potential and hydrological history in a variety of settings, including surface mineralized terraces, associated stream deposits, and subsurface environments where organic remains may have been well protected from oxidation. Previous attempts to identify martian spring deposits from orbit have been general or limited by resolution of available data [12-14]. However, new satellite imagery from HiRISE has a resolution of 28 cm/pixel, and based on these new data, we have interpreted several features in Vernal Crater, Arabia Terra as ancient hydrothermal springs [15, 16].

  15. Mapping of hydrothermally altered rocks using airborne multispectral scanner data, Marysvale, Utah, mining district

    USGS Publications Warehouse

    Podwysocki, M.H.; Segal, D.B.; Jones, O.D.

    1983-01-01

    Multispectral data covering an area near Marysvale, Utah, collected with the airborne National Aeronautics and Space Administration (NASA) 24-channel Bendix multispectral scanner, were analyzed to detect areas of hydrothermally altered, potentially mineralized rocks. Spectral bands were selected for analysis that approximate those of the Landsat 4 Thematic Mapper and which are diagnostic of the presence of hydrothermally derived products. Hydrothermally altered rocks, particularly volcanic rocks affected by solutions rich in sulfuric acid, are commonly characterized by concentrations of argillic minerals such as alunite and kaolinite. These minerals are important for identifying hydrothermally altered rocks in multispectral images because they have intense absorption bands centered near a wavelength of 2.2 ??m. Unaltered volcanic rocks commonly do not contain these minerals and hence do not have the absorption bands. A color-composite image was constructed using the following spectral band ratios: 1.6??m/2.2??m, 1.6??m/0.48??m, and 0.67??m/1.0??m. The particular bands were chosen to emphasize the spectral contrasts that exist for argillic versus non-argillic rocks, limonitic versus nonlimonitic rocks, and rocks versus vegetation, respectively. The color-ratio composite successfully distinguished most types of altered rocks from unaltered rocks. Some previously unrecognized areas of hydrothermal alteration were mapped. The altered rocks included those having high alunite and/or kaolinite content, siliceous rocks containing some kaolinite, and ash-fall tuffs containing zeolitic minerals. The color-ratio-composite image allowed further division of these rocks into limonitic and nonlimonitic phases. The image did not allow separation of highly siliceous or hematitically altered rocks containing no clays or alunite from unaltered rocks. A color-coded density slice image of the 1.6??m/2.2??m band ratio allowed further discrimination among the altered units. Areas containing zeolites and some ash-fall tuffs containing montmorillonite were readily recognized on the color-coded density slice as having less intense 2.2-??m absorption than areas of highly altered rocks. The areas of most intense absorption, as depicted in the color-coded density slice, are dominated by highly altered rocks containing large amounts of alunite and kaolinite. These areas form an annulus, approximately 10 km in diameter, which surrounds a quartz monzonite intrusive body of Miocene age. The patterns of most intense alteration are interpreted as the remnants of paleohydrothermal convective cells set into motion during the emplacement of the central intrusive body. ?? 1983.

  16. From the Veins to the Heart: A Rare Cause of Varicose Veins

    PubMed Central

    Dalla Vestra, Michele; Grolla, Elisabetta; Bonanni, Luca; Dorrucci, Vittorio; Presotto, Fabio; Rigo, Fausto

    2015-01-01

    The presence of pulsating varicous veins is an uncommon finding, generically attributed to right heart failure. The precise causes of this phenomenon have been poorly defined in the literature. The finding of this infrequent condition is important because it may be a sign of major diseases, often not known. Here we described a 75-year-old woman presented to the Angiology Unit for the presence of bilateral pulsatile swelling in her groin and along both lower limbs. A bedside ultrasound examination showed an arterial like pulsating flow both in the superficial and in the deep veins of the lower limbs due to a severe tricuspid regurgitation not previously known. PMID:26090263

  17. Similar quartz crystallographic textures in rocks of continental earth's crust (by neutron diffraction data): I. Quartz textures in monomineral rocks

    SciTech Connect

    Nikitin, A. N., E-mail: nikitin@nf.jinr.ru; Ivankina, T. I. [Joint Institute for Nuclear Research (Russian Federation); Ullemeyer, K. [Universitaet Kiel, Institut fuer Geowissenschaften (Germany); Vasin, R. N. [Joint Institute for Nuclear Research (Russian Federation)

    2008-09-15

    Quartz crystallographic textures in different rocks have been investigated by neutron diffraction. Various types of crystallographic textures of quartz-bearing mineral associations in monomineral and multiphase rocks from a representative collection of samples have been revealed and classified. Experimental investigations have been performed on special neutron texture diffractometers designed at the Frank Laboratory of Neutron Physics and mounted in the seventh channel of the IBR-2 reactor at the Joint Institute for Nuclear Research (Dubna).

  18. Jurassic hot spring deposits of the Deseado Massif (Patagonia, Argentina): Characteristics and controls on regional distribution

    Microsoft Academic Search

    Diego M. Guido; Kathleen A. Campbell

    2011-01-01

    The Deseado Massif, Santa Cruz Province, Argentinean Patagonia, hosts numerous Middle to Late Jurassic age geothermal and epithermal features represented by siliceous and calcareous chemical precipitates from hot springs (sinters and travertines, respectively), hydrothermal breccias, quartz veins, and widespread hydrothermal silicification. They indicate pauses in explosive volcanic activity, marking the final stages in the evolution of an extensive Jurassic (ca.

  19. Geology of the Early Archean Mid-Ocean Ridge Hydrothermal System in the North Pole Dome, Pilbara Craton, Western Australia

    NASA Astrophysics Data System (ADS)

    Kitajima, K.; Maruyama, S.

    2007-12-01

    An Archean hydrothermal system in the North Pole Dome, Pilbara Craton is associated with extensive fluid circulation driven by numerous extensional fracture systems and the underlying heat source. The fracture system is now occupied by abundant fine-grained quartz aggregate, hence we call this as silica dikes. Some of the fracture system extends deeper structural levels as listric normal faults down to 1000 m depth in the MORB crust. Barite-bearing fine-grained quartz predominant mineralogy indicates the extensive development of fracturing and quenching in a short time. Accompanying the fluid circulation, the extensive metasomatism proceeded to form the four different chemical courses, (1) silicification, (2) carbonation, (3) potassium-enrichment, and (4) Fe- enrichment. Silicification occurs along the silica dikes, carbonated greenstones are distributed relatively shallower level. Potassium-enriched (mica-rich) greenstones occur at the top of the greenstone sequence, and Fe-enriched (chlorite-rich) greenstones are distributed at lower part of the basaltic greenstones. The down going fluid precipitated carbonate-rich layer at shallow levels, whereas depleted in SiO2. Then, the fluid went down to more deeper level, and was dissolved SiO2 at high temperature (~350°C) and chlorite-rich greenstone was formed by water-rock interaction. The upwelling fluid precipitated dominantly SiO2 and formed silica dikes. Silica dikes cement the fractures formed by extensional faulting at earliest stage of development of oceanic crust. Therefore, the hydrothermal system must have related to normal fault system simultaneously with MORB volcanism. Particularly the greenish breccia with cherty matrix (oregano chert) was formed at positions by upwelling near ridge axis. After the horizontal removal of MORB crust from the ridge-axis with time, the propagating fracture into deeper levels, transports hydrothermal fluids into 500-1000 m depth range where metasomatic element exchange between fluid and country rocks proceed and transport rock components to the surface through the fractures.

  20. Calibrated Hydrothermal Parameters, Barrow, Alaska, 2013

    DOE Data Explorer

    Atchley, Adam; Painter, Scott; Harp, Dylan; Coon, Ethan; Wilson, Cathy; Liljedahl, Anna; Romanovsky, Vladimir

    A model-observation-experiment process (ModEx) is used to generate three 1D models of characteristic micro-topographical land-formations, which are capable of simulating present active thaw layer (ALT) from current climate conditions. Each column was used in a coupled calibration to identify moss, peat and mineral soil hydrothermal properties to be used in up-scaled simulations. Observational soil temperature data from a tundra site located near Barrow, AK (Area C) is used to calibrate thermal properties of moss, peat, and sandy loam soil to be used in the multiphysics Advanced Terrestrial Simulator (ATS) models. Simulation results are a list of calibrated hydrothermal parameters for moss, peat, and mineral soil hydrothermal parameters.

  1. Hydrothermal Ni Prospectivity Analysis of Tasmania, Australia

    NASA Astrophysics Data System (ADS)

    Gonzalez-Alvalez, I.; Porwal, A.; McCuaig, T. C.

    2009-04-01

    Tasmania contains the largest hydrothermal Ni deposit in Australia: Avebury (118,000 Ni metal tonnes). This Devonian deposit was discovered in 1998 in the Dundas geological region, and represents an outstanding example of hydrothermal Nickel sulphide mineralization type. Avebury Ni deposit is a system of hydrothermal Ni ore bodies. It is hosted by an intensely altered and serpentinized Cambrian ultramafic suite in close proximity to major structural features. The mineralization is considered to be the result of hydrothermal scavenging and remobilization of the original nickel content of the mafic/ultramafic rocks in the area, and subsequent re-deposition in favourable structural traps. The mineralization is spatially and temporally related to a large granitic intrusion, the Heemskirk Granite, which is considered to be the source of the hydrothermal fluids as well as the necessary thermal gradients for the circulation of the fluids. Tasmania is largely covered by the Jurassic Ferrar Continental Flood basalt Province in the East and presents early Cambrian ultramafic-mafic complexes in the West. The Ferrar large igneous province (LIP) extends over to Antarctica and is related to the Karoo Province in southern Africa that comprises tholeiitic lava flows, sills, and dyke swarms. The Ferrar and Karoo provinces were associated with the same thermal anomaly that was involved in the break up of Gondwana. The presence of mafic/ultramafic rocks in favourable lithological packages and/or structural traps along the margins of the province, as well as several prospective reduced or reactive sedimentary packages within and around the Ferrar indicate that this LIP could represent a novel promising ground for Ni hydrothermal exploration. Based on this prospective geological background, a prospectivity analysis for hydrothermal Ni deposits was carried out on regional scale for the entire state of Tasmania. A conceptual model of hydrothermal nickel mineral system was used to identify the following as the most important exploration criteria for hydrothermal nickel deposits: (i) potential nickel sources, (ii) heat and fluid sources, (iii) permeable transportation channels for circulating hydrothermal fluids, and (iv) prospective lithological and structural traps conducive for sulphur saturation and deposition of nickel sulphides. Available public domain exploration datasets were processed using GIS functionalities to derive a series of derivative GIS layers that could be used as proxies for each of the above exploration criteria. These included komatiites/picrites/mafic-ultramafic rocks formed from magma with >7% MgO, large igneous province; major faults; crustal contamination, older sulphur bearing rock suites, redox gradients and/or reduced fluids highly concentrated in chloride etc.. A two-pronged approach involving GIS-assisted manual prospectivity analysis and GIS-based (automated) prospectivity analysis was used for identifying the most prospective ground for hydrothermal nickel deposits in Tasmania. The manual analysis involved a conceptual review of all geological regions of the state, while the GIS-based automated approach used a spatial fuzzy model. The results of the two analyses were subsequently integrated and, after a detailed geological follow-up study, were used to generate a hydrothermal nickel prospectivity map of the state. The methodology developed in this study could be potentially applied to frontier exploration grounds with similar geological setting, such as Papua New Guinea.

  2. Hydrothermal Ni Prospectivity Analysis of Tasmania, Australia

    NASA Astrophysics Data System (ADS)

    Gonzalez-Alvarez, I.; Porwal, A.; McCuaig, T. C.; Maier, W.

    2009-04-01

    Tasmania contains the largest hydrothermal Ni deposit in Australia: Avebury (118,000 Ni metal tonnes). This Devonian deposit was discovered in 1998 in the Dundas geological region, and consists of a system of hydrothermal Ni ore bodies. They are hosted by an intensely altered and serpentinized Cambrian ultramafic suite in close proximity to major structural features. The mineralization is considered to be the result of hydrothermal scavenging and remobilization of the original nickel content of mafic/ultramafic rocks in the area, and subsequent re-deposition in favourable structural traps. This is based on the low sulphur, low Cu and Platinum element content of the mineralization. The mineralization is spatially (at the edge) and temporally related to a large granitic intrusion, the Heemskirk Granite, which is considered to be the source of the hydrothermal fluids as well as the necessary thermal gradients for the circulation of the fluids. Tasmania is largely covered by the Jurassic Ferrar continental flood basalt province in the East and constrains a number of early Cambrian ultramafic-mafic complexes in the West. The Ferrar large igneous province (LIP) extends over to Antarctica and is temporally and genetically related to the Karoo igneous province in southern Africa that comprises tholeiitic lava flows, sills, and dyke swarms. The Ferrar and Karoo igneous provinces were associated with the same thermal anomaly that was responsible for the break up of eastern Gondwana at ca 180 Ma. Despite of timeframe differences between the Avebury Ni deposits and the Ferrar LIP emplacement, similar geological settings to the Avebury could be duplicated along the Ferrar LIP. The presence of mafic/ultramafic rocks in favourable lithological packages and/or structural traps along the margins of the province indicate that this LIP could represent a possible exploration target for Ni hydrothermal deposits. Based on this background, a prospectivity analysis for hydrothermal Ni deposits was carried out on a regional scale for the entire state of Tasmania to explore the prospectivity of for hydrothermal Ni deposits of this part of the Ferrar LIP for. A conceptual model of hydrothermal nickel mineral systems was used to identify the following as the most important exploration criteria for hydrothermal nickel deposits: (i) presence of potential nickel sources, (ii) heat and fluid sources, (iii) permeable transportation channels for circulating hydrothermal fluids, and (iv) prospective lithological and structural traps conducive for sulphur saturation and deposition of nickel sulphides. Available public domain exploration datasets were processed using GIS functionalities to derive a series of derivative GIS layers that could be used as proxies for each of the above exploration criteria. These included mafic-ultramafic rocks formed from magma with >7% MgO, large igneous province; major faults, and mineral alteration assemblages that could indicate redox gradients and/or reduced fluids highly concentrated in chloride etc. A two-pronged approach involving GIS-assisted manual prospectivity analysis and GIS-based (automated) prospectivity analysis was used for identifying the most prospective ground for hydrothermal nickel deposits in Tasmania. The manual analysis involved a conceptual review of all geological regions of the state, while the GIS-based automated approach used a spatial fuzzy model. The results of the two analyses were subsequently integrated and, after a detailed geological follow-up study, were used to generate a hydrothermal nickel prospectivity map of the state. The methodology developed in this study could be potentially applied to frontier exploration grounds with similar geological setting, such as Papua New Guinea.

  3. Hydrothermal alteration in the EPF replacement wells, Olkaria Geothermal field, Kenya

    SciTech Connect

    Mungania, J. [Kenya Power & Lighting Co. Ltd., Naivasha (Kenya)

    1996-12-31

    Olkaria Geothermal area is located in the central sector of the Kenya, Rift Valley. A 45MW Geothermal power station has been operational at Olkaria since 1985 supplied by 22 of the 26 wells drilled in the Eastern production field (EPF). Between 1988 and 1993, eight more wells referred to as {open_quote}replacement wells{close_quote} were drilled in the same field to boost steam supply to the station. Petrographic analyses of the drill cuttings is usually done to determine detail stratigraphy of the field, extends of hydrothermal activity, subsurface structures and other parameters which may influence production potential of a well. Analyses of the drill cuttings from the EPF wells show that: Variations in the whole rock alteration intensities correlate with differences in rocktypes. Permeable horizons, especially the productive feeder zones are well marked by enhanced hydrothermal minerals depositions, mainly quartz, calcite, pyrite and epidote. Other aspects of state of reservoir like boiling are signified by presence of bladed calcite.

  4. Coupling geophysical investigation with hydrothermal modeling to constrain the enthalpy classification of a potential geothermal resource

    NASA Astrophysics Data System (ADS)

    White, J. T.; Karakhanian, A.; Connor, C. B.; Connor, L.; Hughes, J. D.; Malservisi, R.; Wetmore, P.

    2015-06-01

    An appreciable challenge in volcanology and geothermal resource development is to understand the relationships between volcanic systems and low-enthalpy geothermal resources. The enthalpy of an undeveloped geothermal resource in the Karckar region of Armenia is investigated by coupling geophysical and hydrothermal modeling. The results of 3-dimensional inversion of gravity data provide key inputs into a hydrothermal circulation model of the system and associated hot springs, which is used to evaluate possible geothermal system configurations. Hydraulic and thermal properties are specified using maximum a priori estimates. Limited constraints provided by temperature data collected from an existing down-gradient borehole indicate that the geothermal system can most likely be classified as low-enthalpy and liquid dominated. We find the heat source for the system is likely cooling quartz monzonite intrusions in the shallow subsurface and that meteoric recharge in the pull-apart basin circulates to depth, rises along basin-bounding faults and discharges at the hot springs. While other combinations of subsurface properties and geothermal system configurations may fit the temperature distribution equally well, we demonstrate that the low-enthalpy system is reasonably explained based largely on interpretation of surface geophysical data and relatively simple models.

  5. Hydrothermal plumes along segments of contrasting magmatic influence, 158888200

    E-print Network

    Langmuir, Charles H.

    ridges have emphasized a positive correlation between local magmatic budget and hydrothermal activity the segment-scale incongruity between hydrothermal activity and magmatic budget, the fraction of total ridge to predictions based on data from other Pacific ridges, hydrothermal plumes over the inflated 168N segment were

  6. Calcium Isotope Fractionation in mid-ocean ridge hydrothermal systems

    Microsoft Academic Search

    M. Sharma; C. Holmden

    2008-01-01

    The purpose of this study is to investigate Ca isotope fractionation during hydrothermal alteration of mid- ocean ridge basalts. Both high and low temperature hydrothermal fluids are enriched in calcium relative to seawater reflecting its derivation from the ocean crust. Indeed, hydrothermal alteration at ridge-crests and at ridge-flanks provides significant amounts of Ca and affects the Ca isotopic composition of

  7. Biogeochemistry of hydrothermally and adjacent non-altered soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a field/lab project, students in the Soil Biogeochemistry class of the University of Nevada, Reno described and characterized seven pedons, developed in hydrothermally and adjacent non-hydrothermally altered andesitic parent material near Reno, NV. Hydrothermally altered soils had considerably lo...

  8. Olivine Carbonation and Multiple Episodes of Carbonate Veining during Basement Rock Denudation in an Oceanic Core Complex, ODP Site 1275, Mid-Atlantic Ridge: A Natural Analog for Engineered Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    Schroeder, T. J.; Bach, W.; Joens, N.; Rausch, S.; Monien, P.; Kluegel, A.

    2014-12-01

    Carbonate precipitation in oceanic olivine-bearing rocks provides a natural case to study engineered CO2-sequestration via olivine carbonation. ODP Site 1275 recovered tectonically denuded gabbro and troctolite on the west flank of the Mid-Atlantic Ridge (15°45'N). Carbonate veins comprise ~0.15 vol.% of the recovered core, corresponding to CO2 uptake of only 0.075 wt.%. However, troctolite cores are comprised of 0.8 vol.% calcite veins, and individual troctolite samples contain up to 15 vol.% calcite that directly replaced olivine in association with talc. Carbonate precipitated from multiple types of fluids during and following denudation. Calcite replaced olivine concurrently with the formation of high-temperature (?18OSMOW = 11 to 20‰, corresponding to 75-180°C for fluid ?18OSMOW of 0‰) calcite veins in active shear zones. These veins are enriched in LREEs (2-10x chondrite) with strong positive Eu anomalies (Eu/Eu* = 5 to 500), and have 87/86Sr ratios of ~0.704 and ?13CVPDB ranging from -2 to -5‰. Later veins (70% calcite and 30% aragonite) cut high-T veins. These veins precipitated near seawater temperatures (?18OSMOW ~ 35.1), and have seawater C and Sr isotopic signatures. Both late calcite and aragonite veins have lower REE contents than high-T veins and have little or no Eu anomalies; aragonite veins have negative Ce anomalies. These low-T veins precipitated in both gabbro and troctolite from seawater with varying degrees of rock interaction. High-T veins and replacive calcite precipitated from a mixture of seawater and high-T hydrothermal fluids, and are common in troctolite but rare in gabbro. Geochemical reaction path modeling suggests that the replacive calcite-talc assemblage in troctolite forms only at high fluid-to-rock ratios. The calcite's low 87/86Sr ratios, however, indicate that the seawater-derived fluids had exchanged Sr with large volumes of rock. The olivine carbonation may hence result from upflow of deeply rooted fluids during basement denudation.

  9. Hydrothermal alteration of sediments associated with surface emissions from the Cerro Prieto geothermal field, Baja, California, Mexico

    SciTech Connect

    Valette-Silver, J.N.; Esquer-Patino, I.; Elders, W.A.; Collier, P.C.; Hoagland, J.R.

    1981-01-01

    Surface emissions from the Cerro Prieto geothermal reservoir are restricted to a 100 km/sup 2/ area on the western side of the field, near the volcano Cerro Prieto and the lake Laguna Vulcano. Some 57 surface emissions, explored in 1979, were classified into hot springs, mud pots, pools, fumaroles and geysers (Valette and Esquer-Patino, 1979). 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/sup 0/C: increase of quartz, feldspar and illite, with subsequent disappearance of kaolinite, montmorillonite, calcite and dolomite. These mineral assemblages seem to be characteristics of the discharge from high intensity geothermal fields.

  10. Kinematics of crystal growth in syntectonic fibrous veins

    Microsoft Academic Search

    J. L. Urai; P. F. Williams; H VANROERMUND

    1991-01-01

    Abstract--Detaded observations of a set of fibrous antitaxial calcite veins in a slate reveal that some,of the calcite fibres do not connect material markers,on both sides of the vein and can therefore not have tracked the full opening trajectory dunng,vein growth. Thts calls for a better understanding,of the mechanisms,of fibre formation and reliable criteria to test the tracking hypothesis. Based

  11. Can vein patterns be used to estimate rock permeabilities?

    NASA Astrophysics Data System (ADS)

    Koehn, Daniel; Vass, Anna; Ghani, Irfan; Toussaint, Renaud; Bons, Paul; Gomez-Rivas, Enrique; Urai, Janos L.; Arndt, Max; Virgo, Simon; Wendler, Frank; Blum, Philipp; Schwarz, Jens-Oliver

    2014-05-01

    Fracturing of rocks due to tectonic stresses or local high fluid pressures and the formation of fluid pathways is important for a whole range of industrially relevant processes in the Earth's upper crust reaching from groundwater transport, hydrocarbon migration to geothermal systems. Fracturing and the opening of fluid pathways become especially important in tight rocks where fluid migration through the rock matrix is restricted. In addition observations show that fractures are often partly or completely sealed and occur as veins in geological systems. How can we interpret the permeability of these vein systems? The internal structure of veins often indicates that they are formed by several cracking and sealing events. In addition some geological systems contain partly sealed veins that have a preserved porosity and may add to the overall permeability of the system. We are comparing field areas that contain different vein patterns with hydrodynamic numerical models where fractures develop as a function of gravity, extension and fluid pressure gradients. In addition fractures seal where the developing veins can have variable properties in terms of elasticity, breaking strength and porosity. Results indicate that permeability in such systems is not a constant but may vary strongly over time. In an active system the amount of veins and number of open fractures depends not only on the timing of sealing but also on the breaking strength of the veins. Strong veins can clog the system whereas weak veins tend to lead to possible connected fracture networks. In addition one cannot link veins directly to fluid flow, intense veining does not mean that the system has or had a high permeability. We will present a first attempt to classify different fracturing and sealing systems based on field observations and numerical models.

  12. Identification of hydrothermal alteration minerals for exploring of porphyry copper deposit using ASTER data, SE Iran

    NASA Astrophysics Data System (ADS)

    Pour, Amin Beiranvnd; Hashim, Mazlan

    2011-11-01

    The NW-SE trending Central Iranian Volcanic Belt hosts many well-known porphyry copper deposits in Iran. It becomes an interesting area for remote sensing investigations to explore the new prospects of porphyry copper and vein type epithermal gold mineralization. Two copper mining districts in southeastern segment of the volcanic belt, including Meiduk and Sarcheshmeh have been selected in the present study. The performance of Principal Component Analysis, band ratio and Minimum Noise Fraction transformation has been evaluated for the visible and near infrared (VNIR) and, shortwave infrared (SWIR) subsystems of ASTER data. The image processing techniques indicated the distribution of iron oxides and vegetation in the VNIR subsystem. Hydrothermal alteration mineral zones associated with porphyry copper mineralization identified and discriminated based on distinctive shortwave infrared (SWIR) properties of the ASTER data in a regional scale. These techniques identified new prospects of porphyry copper mineralization in the study areas. The spatial distribution of hydrothermal alteration zones has been verified by in situ inspection, X-ray diffraction (XRD) analysis, and spectral reflectance measurements. Results indicated that the integration of the image processing techniques has a great ability to obtain significant and comprehensive information for the reconnaissance stages of porphyry copper exploration in a regional scale. The results of this research can assist exploration geologists to find new prospects of porphyry copper and gold deposits in the other virgin regions before costly detailed ground investigations. Consequently, the introduced image processing techniques can create an optimum idea about possible location of the new prospects.

  13. Multiple Abdominal Veins Thrombosis Secondary to Protein S Deficiency - A Case Report

    PubMed Central

    Kodali, Venkata Umakant; Borra, Seshulakshmi; Mandarapu, Surendra Babu; Sanda, Mallikarjuna Rao

    2014-01-01

    Abdominal venous thrombosis may present either as Budd-Chiari syndrome (BCS) caused by hepatic vein or proximal inferior vena cava (IVC) obstruction or as an extra hepatic portal obstruction (EHPVO) caused by Portal vein thrombosis or mesenteric vein thrombosis, but a mixed involvement is uncommon. Multiple abdominal venous obstructions presenting with thrombosis of hepatic vein, IVC, portal vein and renal vein are very rarely seen . We are reporting a rare case with thrombosis of IVC, hepatic vein, portal vein and renal vein, with protein S and protein C deficiencies, which was managed by giving anticoagulant therapy. PMID:25121018

  14. Late failure of reversed vein bypass grafts.

    PubMed Central

    Berkowitz, H D; Greenstein, S; Barker, C F; Perloff, L J

    1989-01-01

    Late failure of reversed vein bypass grafts is preceded by the appearance of stenotic lesions, which progress to total occlusion. These lesions appear either as intrinsic graft lesions or as new arteriosclerotic lesions in contiguous arteries. The present study summarizes the University of Pennsylvania experience with these lesions in 521 vein grafts inserted from 1979 to 1985. The grafts were grouped according to the site of the distal anastomosis; 231 above-knee popliteal (FP AK), 171 below-knee popliteal (FP BK), and 119 tibial (FT). The overall incidence of stenotic lesions was essentially identical with the three grafts (21%), but the relative incidence of intrinsic graft to arterial lesions was higher with the more distal grafts. The most common graft lesions developed adjacent to the proximal anastomosis, which is the narrowest part of a reversed vein graft. The popliteal artery was the most common site of outflow stenosis. There was negligible incidence of tibial lesions. The most common inflow arterial lesion was located in the common femoral and iliac arteries. The superficial femoral artery (SFA) was a rare site of inflow stenosis, even though it was at risk because 96 grafts originated from the SFA or popliteal artery. Sixty-seven per cent of the graft and 52% of the arterial lesions were treated successfully by percutaneous transluminal angioplasty; the rest had minor surgical revisions. This resulted in a 19%, 10%, and 9% improvement in 5-year patency for the FT, FP BK, and FP AK bypasses. These results justify an aggressive policy of graft surveillance to identify and treat stenotic graft lesions before graft occlusion. PMID:2589891

  15. Interpretation of fluid inclusions in quartz deformed by weak ductile shearing: reconstruction of differential stress magnitudes and pre-deformation fluid properties

    NASA Astrophysics Data System (ADS)

    Tarantola, Alexandre; Diamond, Larryn W.

    2015-04-01

    A well developed theoretical framework is available in which paleofluid properties, such as chemical composition and density, can be reconstructed from fluid inclusions in minerals that have undergone no ductile deformation. Fluid inclusions are known to reequilibrate during strong post-entrapment changes in hydrostatic confining pressure (e.g. Sterner and Bodnar 1989). The present study extends this framework to encompass fluid inclusions hosted by quartz that has undergone weak ductile deformation following fluid entrapment. Recent piston-cylinder experiments (Griggs apparatus) made on single quartz crystals have shown that such deformation causes inclusions to become dismembered into clusters of irregularly shaped relict inclusions surrounded by planar arrays of tiny, new-formed (neonate) inclusions (Diamond et al. 2010; Tarantola et al. 2010, 2012). Comparison of the experimental samples with a naturally sheared quartz vein from Grimsel Pass, Central Alps, Switzerland, reveals striking similarities. This strong concordance justifies applying the experimentally derived rules of fluid inclusion behaviour to nature. Thus, planar arrays of dismembered inclusions defining cleavage planes in quartz may be taken as diagnostic of small amounts of intracrystalline strain. Deformed inclusions preserve their pre-deformation concentration ratios of gases to electrolytes, but their H2O contents typically have changed. Morphologically intact inclusions, in contrast, preserve the pre-deformation composition and density of their originally trapped fluid. The orientation of the maximum principal compressive stress (?1) at the time of shear deformation can be derived from the pole to the cleavage plane within which the dismembered inclusions are aligned. Finally, the density of neonate inclusions is commensurate with the pressure value of ?1 at the temperature and time of deformation. This last rule offers a means to estimate magnitudes of shear stresses from fluid inclusion studies. Application of this new paleopiezometer approach to the Grimsel vein yields a differential stress (?1 - ?3) of ~300 MPa at 390 ± 30 °C during late Miocene NNW-SSE orogenic shortening and regional uplift of the Aar Massif. This differential stress resulted in strain-hardening of the quartz at very low total strain (<5%) while nearby shear zones were accommodating significant displacements. Further implementation of these experimentally derived rules should provide new insight into processes of fluid-rock interaction in the ductile regime within the Earth's crust. Diamond, L.W., Tarantola, A., Stünitz, H., 2010. Modification of fluid inclusions in quartz by deviatoric stress II: Experimentally induced changes in inclusion volume and composition. Contrib. Mineral. Petrol. 160, 845-864. Sterner, S.M. and Bodnar, R.J., 1989. Synthetic fluid inclusions-VII. Re-equilibration of fluid inclusions in quartz during laboratory-simulated metamorphic burial and uplift. J. Metamorph. Geol., 7, 243¬-260. Tarantola, A., Diamond, L.W., Stünitz, H., 2010. Modification of fluid inclusions in quartz by deviatoric stress. I: Experimentally induced changes in inclusion shapes and microstructures. Contrib. Mineral. Petrol. 160, 825-843. Tarantola, A., Diamond, L.W., Stünitz, H., Thust, A., Pec, M., 2012. Modification of fluid inclusions in quartz by deviatoric stress. III: Influence of principal stresses on inclusion density and orientation. Contrib. Mineral. Petrol. 164, 527-550.

  16. Soil chemistry in lithologically diverse datasets: the quartz dilution effect

    USGS Publications Warehouse

    Bern, Carleton R.

    2009-01-01

    National- and continental-scale soil geochemical datasets are likely to move our understanding of broad soil geochemistry patterns forward significantly. Patterns of chemistry and mineralogy delineated from these datasets are strongly influenced by the composition of the soil parent material, which itself is largely a function of lithology and particle size sorting. Such controls present a challenge by obscuring subtler patterns arising from subsequent pedogenic processes. Here the effect of quartz concentration is examined in moist-climate soils from a pilot dataset of the North American Soil Geochemical Landscapes Project. Due to variable and high quartz contents (6.2–81.7 wt.%), and its residual and inert nature in soil, quartz is demonstrated to influence broad patterns in soil chemistry. A dilution effect is observed whereby concentrations of various elements are significantly and strongly negatively correlated with quartz. Quartz content drives artificial positive correlations between concentrations of some elements and obscures negative correlations between others. Unadjusted soil data show the highly mobile base cations Ca, Mg, and Na to be often strongly positively correlated with intermediately mobile Al or Fe, and generally uncorrelated with the relatively immobile high-field-strength elements (HFS) Ti and Nb. Both patterns are contrary to broad expectations for soils being weathered and leached. After transforming bulk soil chemistry to a quartz-free basis, the base cations are generally uncorrelated with Al and Fe, and negative correlations generally emerge with the HFS elements. Quartz-free element data may be a useful tool for elucidating patterns of weathering or parent-material chemistry in large soil datasets.

  17. Micromechanics of quartz sand breakage in a fractal context

    NASA Astrophysics Data System (ADS)

    Assadi Langroudi, Arya; Jefferson, Ian; O'hara-Dhand, Kenneth; Smalley, Ian

    2014-04-01

    From a Quaternary science perspective, sand-sized quartz as well as silt-sized quartz is often acknowledged as final products of glacial abrasion through different evolution mechanisms. This view challenges the existence of any universal comminution process, which may relate the formation of detrital quartz sand and silt. The contribution of grain size, energy input, and crystalline integrity in the scale of quartz crushability has long been the matter of much debate. The present empirical work examines the micromechanics of sand-to-silt size reduction in the quartz material. A series of grinding experiments was performed on Leighton Buzzard Lower Greensand using a high-energy agate disc mill. Analogous conditions to glacial abrasion are provided due to the combined abrasion between grains' asperity tips, and also between grains and rotating smooth tungsten carbide pestle. Simulation of discontinuous grain breakage allowed the examination of grains' crystalline defects. To enable an objective assessment of micromechanics of size reduction, measurements of particle and mode size distribution, fractal indexes and micro-morphological signatures were made. The crushing approach was probed through varied grinding times at a constant energy input, as well as varied energy inputs at constant grinding time. Breakage pathway was inspected via laser diffraction spectroscopy and transmission light microscopy. Results suggested that the grain breakdown is not necessarily an energy-dependent process. Non-crystallographically pure (amorphous) quartz sand and silt are inherently breakable materials through a fractal breakdown process. Results also revealed that the internal defects in quartz are independent from size and energy input.

  18. [Catheter-based treatment for acute deep vein thrombosis].

    PubMed

    Engelberger, Rolf P; Alatri, Adriano; Qanadli, Salah D; Calanca, Luca; Mazzolai, Lucia

    2015-02-01

    Nearly half of patients with acute lower limb deep vein thrombosis (DVT) develop a post-thrombotic syndrome (PTS). This risk is particularly high in case of proximal DVT of the common femoral and iliac vein, the major lower limbs venous outflow vessel. Several studies have demonstrated that PTS incidence can be reduced with early vein recanalisation. Currently, catheter-based recanalisation therapies can be offered to selected patients with acute ilio-femoral deep vein thrombosis. Aim of the present article is to summarize current knowledge on these catheter-based recanalisation therapies. PMID:25854044

  19. Finger-vein verification based on multi-features fusion.

    PubMed

    Qin, Huafeng; Qin, Lan; Xue, Lian; He, Xiping; Yu, Chengbo; Liang, Xinyuan

    2013-01-01

    This paper presents a new scheme to improve the performance of finger-vein identification systems. Firstly, a vein pattern extraction method to extract the finger-vein shape and orientation features is proposed. Secondly, to accommodate the potential local and global variations at the same time, a region-based matching scheme is investigated by employing the Scale Invariant Feature Transform (SIFT) matching method. Finally, the finger-vein shape, orientation and SIFT features are combined to further enhance the performance. The experimental results on databases of 426 and 170 fingers demonstrate the consistent superiority of the proposed approach. PMID:24196433

  20. Absence of the superior petrosal veins and sinus: Surgical considerations

    PubMed Central

    Matsushima, Ken; Ribas, Eduardo Santamaria Carvalhal; Kiyosue, Hiro; Komune, Noritaka; Miki, Koichi; Rhoton, Albert L.

    2015-01-01

    Background: The superior petrosal vein, one of the most constant and largest drainage pathways in the posterior fossa, may result in complications if occluded. This study calls attention to a unique variant in which the superior petrosal veins and sinus were absent unilaterally, and the venous drainage was through the galenic and tentorial drainage groups. Methods: This study examines one venogram and another anatomic specimen in which the superior petrosal vein and sinus were absent. Results: The superior petrosal veins, described as 1–3 bridging veins, emptying into the superior petrosal sinus, are the major drainage pathways of the petrosal group of posterior fossa veins. In the cases presented, the superior petrosal vein and sinus were absent and venous drainage was through the galenic and tentorial groups, including the lateral mesencephalic or bridging vein on the tentorial cerebellar surface. Conclusions: In cases in which the superior petrosal sinus and veins are absent, care should be directed to preserving the collateral drainage through the galenic and tentorial tributaries. Although surgical strategies for intraoperative management and preservation of venous structures are still controversial, knowledge of the possible anatomical variations is considered to be essential to improve surgical outcomes. PMID:25745589

  1. Deep Vein Thrombosis - Multiple Languages: MedlinePlus

    MedlinePLUS

    ... sharing features on this page, please enable JavaScript. Arabic (???????) Bosnian (Bosanski) French (français) Russian (???????) Somali (af Soomaali) Spanish (español) Arabic (???????) Deep Vein Thrombosis (DVT) (Arabic) ??????? Bilingual ...

  2. Fractionation factor of 238U and 235U isotopes in the process of hydrothermal pitchblende formation: A numerical estimate

    NASA Astrophysics Data System (ADS)

    Chernyshev, I. V.; Dubinina, E. O.; Golubev, V. N.

    2014-09-01

    Owing to the rapid increase in available data on the natural variations of the 238U/235U ratio, new isotopic geochemical mark of redox processes are beginning to emerge. In this connection, numerical estimates of the 238U and 235U fractionation factor (?(UIV-UVI)) accompanying the reduction UVI ? UIV are needed. Such an estimate has been obtained for hydrothermal pitchblende formation based on results of high-precision (±0.06‰) measurements of the 238U/235U ratio in local microsamples of coarse spherulitic pitchblende from carbonate-pitchblende veins at the Oktyabr'sky deposit (Strel'tsovsky uranium ore field, eastern Transbaikal region). For this purpose, we used the formation temperature of hydrothermal pitchblende and a maximum estimate of the fractionation factor for 238U and 235U isotopes in the solution-solid phase system under normal (25°C) conditions (Murphy et al., 2014). The most probable isotopic fractionation factor accompanying pitchblende crystallization from hydrothermal solution at T = 320-250°C falls into the interval ?(UIV-UVI) = 1.00020-1.00023.

  3. Pediatric aneurysms and vein of Galen malformations

    PubMed Central

    Rao, V. R. K.; Mathuriya, S. N.

    2011-01-01

    Pediatric aneurysms are different from adult aneurysms – they are more rare, are giant and in the posterior circulation more frequently than in adults and may be associated with congenital disorders. Infectious and traumatic aneursyms are also seen more frequently. Vein of Galen malformations are even rarer entities. They may be of choroidal or mural type. Based on the degree of AV shunting they may present with failure to thrive, with hydrocephalus or in severe cases with heart failure. The only possible treatment is by endovascular techniques – both transarterial and transvenous routes are employed. Rarely transtorcular approach is needed. These cases should be managed by an experienced neurointerventionist. PMID:22069420

  4. Medical treatment of retinal vein occlusions.

    PubMed

    Parodi, Maurizio Battaglia

    2004-01-01

    The medical treatment of retinal vein occlusion (RVO) is comprised of three main stages: identification and therapy of the detectable risk factors, specific treatment aimed at the occlusive form and treatment of RVO complications. Even though the possible medical management of RVO includes several treatments, the most interesting approaches have been: anticoagulant/antiaggregating agents, troxerutin, corticosteroid, fibrinolytic/thrombolytic agents, and hemodilution. Overall, the medical approach to RVO is still awkward and unsatisfactory. Randomized clinical trials are needed to assess the degree of efficacy of the medical treatment of the specific forms of RVO. PMID:15590533

  5. Lymphangioma: surrounding the ovarian vein and ovary

    PubMed Central

    Gonen, Korcan Aysun; Abali, Remzi; Oznur, Meltem; Erdogan, Cuneyt

    2013-01-01

    Lymphangiomas are usually benign lesions seen in the head and neck region in children. Intra-abdominal localisation is rare and the majority of these cases are in early childhood. Retroperitoneal lymphangiomas constitute approximately 1% of all lymphangiomas. They are generally diagnosed incidentally, may be asymptomatic or may present with a palpable abdominal mass. A limited number of cases of ovarian lymphangiomas have been reported in women, whereas there are no reported cases of paraovarian localisation. We present a rare case of lymphangioma located in bilateral paraovarian region and along the left ovarian vein with radiological findings. PMID:23814093

  6. Variability in the microbial communities and hydrothermal fluid chemistry at the newly discovered Mariner hydrothermal field, southern Lau Basin

    Microsoft Academic Search

    Ken Takai; Takuro Nunoura; Jun-ichiro Ishibashi; John Lupton; Ryohei Suzuki; Hiroshi Hamasaki; Yuichiro Ueno; Shinsuke Kawagucci; Toshitaka Gamo; Yohey Suzuki; Hisako Hirayama; Koki Horikoshi

    2008-01-01

    A newly discovered hydrothermal field called the Mariner field on the Valu Fa Ridge in the southern Lau Basin was explored and characterized with geochemical and microbiological analyses. The hydrothermal fluid discharging from the most vigorous vent (Snow Chimney, maximum discharge temperature 365°C) was boiling at the seafloor at a depth of 1908 m, and two distinct end-member hydrothermal fluids

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

    USGS Publications Warehouse

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

    2009-01-01

    The Assif El Mal Zn-Pb (Cu-Ag) vein system, located in the northern flank of the High Atlas of Marrakech (Morocco), is hosted in a Cambro-Ordovician volcaniclastic and metasedimentary sequence composed of graywacke, siltstone, pelite, and shale interlayered with minor tuff and mudstone. Intrusion of synorogenic to postorogenic Late Hercynian peraluminous granitoids has contact metamorphosed the host rocks giving rise to a metamorphic assemblage of quartz, plagioclase, biotite, muscovite, chlorite, amphibole, chloritoid, and garnet. The Assif El Mal Zn-Pb (Cu-Ag) mineralization forms subvertical veins with ribbon, fault breccia, cockade, comb, and crack and seal textures. Two-phase liquid-vapor fluid inclusions that were trapped during several stages occur in quartz and sphalerite. Primary inclusion fluids exhibit Th mean values ranging from 104??C to 198??C. Final ice-melting temperatures range from -8.1??C to -12.8??C, corresponding to salinities of ???15 wt.% NaCl equiv. Halogen data suggest that the salinity of the ore fluids was largely due to evaporation of seawater. Late secondary fluid inclusions have either Ca-rich, saline (26 wt.% NaCl equiv.), or very dilute (3.5 wt.% NaCl equiv.) compositions and homogenization temperatures ranging from 75??C to 150??C. The ??18O and ??D fluid values suggest an isotopically heterogeneous fluid source involving mixing between connate seawater and black-shale-derived organic waters. Low ??13CVPDB values ranging from -7.5??? to -7.7??? indicate a homogeneous carbon source, possibly organic matter disseminated in black shale hosting the Zn-Pb (Cu-Ag) veins. The calculated ??34SH2S values for reduced sulfur (22.5??? to 24.3???) are most likely from reduction of SO42- in trapped seawater sulfate or evaporite in the host rocks. Reduction of sulfate probably occurred through thermochemical sulfate reduction in which organic matter was oxidized to produce CO2 which ultimately led to precipitation of saddle dolomite with isotopically light carbon. Lead isotope compositions are consistent with fluid-rock interaction that leached metals from the immediate Cambro-Ordovician volcaniclastic and metasedimentary sequence or from the underlying Paleo-Neoproterozoic crustal basement. Geological constraints suggest that the vein system of Assif El Mal formed during the Jurassic opening of the central Atlantic Ocean. ?? Springer-Verlag 2009.

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

    NASA Astrophysics Data System (ADS)

    Bouabdellah, Mohammed; Beaudoin, Georges; Leach, David L.; Grandia, Fidel; Cardellach, Esteve

    2009-08-01

    The Assif El Mal Zn-Pb (Cu-Ag) vein system, located in the northern flank of the High Atlas of Marrakech (Morocco), is hosted in a Cambro-Ordovician volcaniclastic and metasedimentary sequence composed of graywacke, siltstone, pelite, and shale interlayered with minor tuff and mudstone. Intrusion of synorogenic to postorogenic Late Hercynian peraluminous granitoids has contact metamorphosed the host rocks giving rise to a metamorphic assemblage of quartz, plagioclase, biotite, muscovite, chlorite, amphibole, chloritoid, and garnet. The Assif El Mal Zn-Pb (Cu-Ag) mineralization forms subvertical veins with ribbon, fault breccia, cockade, comb, and crack and seal textures. Two-phase liquid-vapor fluid inclusions that were trapped during several stages occur in quartz and sphalerite. Primary inclusion fluids exhibit T h mean values ranging from 104°C to 198°C. Final ice-melting temperatures range from -8.1°C to -12.8°C, corresponding to salinities of ˜15 wt.% NaCl equiv. Halogen data suggest that the salinity of the ore fluids was largely due to evaporation of seawater. Late secondary fluid inclusions have either Ca-rich, saline (26 wt.% NaCl equiv.), or very dilute (3.5 wt.% NaCl equiv.) compositions and homogenization temperatures ranging from 75°C to 150°C. The ?18O and ?D fluid values suggest an isotopically heterogeneous fluid source involving mixing between connate seawater and black-shale-derived organic waters. Low ?13CVPDB values ranging from -7.5‰ to -7.7‰ indicate a homogeneous carbon source, possibly organic matter disseminated in black shale hosting the Zn-Pb (Cu-Ag) veins. The calculated ?34SH2S values for reduced sulfur (22.5‰ to 24.3‰) are most likely from reduction of SO4 2- in trapped seawater sulfate or evaporite in the host rocks. Reduction of sulfate probably occurred through thermochemical sulfate reduction in which organic matter was oxidized to produce CO2 which ultimately led to precipitation of saddle dolomite with isotopically light carbon. Lead isotope compositions are consistent with fluid-rock interaction that leached metals from the immediate Cambro-Ordovician volcaniclastic and metasedimentary sequence or from the underlying Paleo-Neoproterozoic crustal basement. Geological constraints suggest that the vein system of Assif El Mal formed during the Jurassic opening of the central Atlantic Ocean.

  9. Physical and chemical aspects of fluid evolution in hydrothermal ore systems

    SciTech Connect

    Cline, J.S.

    1990-01-01

    A one-dimensional, physical model describing two-phase fluid flow is used to simulate the effect of boiling on silica precipitation in geothermal and epithermal precious metal systems. The extent to which decreasing temperature and fluid vaporization are responsible for quartz precipitation is dependent on three related factors-the temperature of the fluid entering the two-phase system, the change in fluid temperature with respect to distance of fluid travel, and the extent of fluid vaporization in regions of gradual temperature decline. Boiling contributes to significant quartz precipitation in systems with high-temperature basal fluids, and in deeper portions of systems in which extensive vaporization occurs. Temperature reduction is a dominate precipitation mechanism in near-surface regions where temperature reduction is rapid, and in systems with lower temperature fluids. Quartz precipitation is most intense in systems with high mass flux/permeability ratios and low initial fluid temperatures. Geothermal systems with high mass flux/permeability and moderately low initial fluid temperatures are most effective in producing epithermal systems with abundant gold. Fluid evolution during the magnetic-hydrothermal transition and coincident molybdenite precipitation at Questa, New Mexico, has been traced using fluid inclusion microthermometry. The lack of cogenetic liquid- and vapor-rich inclusions, plus final homogenization of most saline, liquid-rich inclusions by halite dissolution indicate that high-salinity fluids were generated by a mechanism other than fluid immiscibility. Pressure flucuations are capable of producing the observed fluids and inclusion behavior. Solubility data indicate that the crystallizing aplite porphyry generated fluids with salinates as high as 57 wt.% NaCl equivalent.

  10. Endovenous saphenous vein ablation in patients with acute isolated superficial-vein thrombosis

    PubMed Central

    2015-01-01

    Objective: The possible benefits of endovenous saphenous ablation (EVSA) as initial treatment in patients presenting with isolated superficial-vein thrombosis (SVT) and saphenous vein reflux include: (1) definitive treatment of the underlying pathology and (2) elimination of the saphenous vein as a path for pulmonary emboli, which (3) may eliminate the need for anticoagulation. Methods: In a ten-year review of 115 limbs presenting with acute isolated SVT, 72 limbs (71 patients) with saphenous reflux were given a choice of two treatments following an explanation of the risks and benefits of each. Group I limbs (n?=?41) were treated with office EVSA using radiofrequency or laser with or without thrombophlebectomy if performed within 45 days of diagnosis. Post-treatment anticoagulants were not given. Group II limbs (n?=?31) were treated with compression hose and repeat Duplex within one week, with added anticoagulants if SVT extended into the thigh. Results: In group I, mean interval from diagnosis to treatment was 13.7 days. One calf deep vein thrombosis was noted. In group II no complications were noted. In late follow-up of group II patients, 12/29 underwent EVSA more than 45 days after initial presentation. Conclusions: The safety and efficacy of EVSA and thrombophlebectomy appear indistinguishable from conservative measures and may be offered as initial treatment to patients presenting with SVT and saphenous reflux. PMID:24307241

  11. PHYSICAL PREPARATION OF QUARTZ SAMPLES FOR Al/Be EXTRACTION This method describes the initial stages of quartz separation from rocks or

    E-print Network

    Stone, John

    the initial stages of quartz separation from rocks or sediments intended for 26 Al/10 Be analysis. Rock samples are crushed, and then crushed rock or natural sediment is sieved to an appropriate grain size on the appropriate amount of rock to crush. The goal is to wind up with ~30 g of quartz at the very end of the quartz

  12. Relict hydrothermal zones in the TAG hydrothermal field, Mid-Atlantic Ridge 26°N, 45°W

    Microsoft Academic Search

    Peter A. Rona; Yury A. Bogdanov; Evengy G. Gurvich; Nick A. Rimski-Korsakov; Anatoly M. Sagalevitch; Mark D. Hannington; Geoffrey Thompson

    1993-01-01

    Two relict hydrothermal zones were delineated between water depths of 3400 and 3500 m at the lower part of the east wall of the rift valley of the Mid-Atlantic Ridge in the TAG hydrothermal field using a deep-towed side scan sonar tow and a camera-temperature tow along the northern 3 km of the wall, and a submersible transect. Named the

  13. Distribution of saphenous vein valves and its pratical importance

    PubMed Central

    Portugal, Isabella Batista Martins; Ribeiro, Igor de Lima; de Sousa-Rodrigues, Célio Fernando; Monte-Bispo, Rodrigo Freitas; da Rocha, Amauri Clemente

    2014-01-01

    Objective Among the veins used as a graft in myocardial revascularizations and ends, great saphenous vein is the most used. Knowing the presence and location of valves has great importance when evaluating the surgical anatomy of the great saphenous vein. Despite major surgical application and many works involving great saphenous vein, the number of valves present in it from the saphenous hiatus to the medial epicondyle of the femur is still described inaccurately. The objective of this study is to quantify the valves of the great saphenous vein from the saphenous hiatus to the medial epicondyle of the femur to determine the best portion of the great saphenous vein to perform revascularization surgeries. Methods This is a crosssectional observational study in which it was analyzed great saphenous vein extracted from 30 cadavers. It was measured the length of the veins; (diameter) at its proximal, middle and distal, quantifying the number of valves in each one and the total number of valves at the great saphenous vein. Results The frequency of valves in the great saphenous vein taken from the medial epicondyle of the femur to the saphenous hiatus was 4.82, ranging between 2 and 9. Moreover, there is a significant difference in the number of valves in the proximal and distal relative to the average. Conclusion the median and distal portions of the saphenous vein in the thigh, are the best options for the realization of bridges due to the fact that these portions have fewer valves which therefore would tend to decrease the risk of complications connected with the valves in these grafts. PMID:25714210

  14. Fungal colonization of an Ordovician impact-induced hydrothermal system

    PubMed Central

    Ivarsson, Magnus; Broman, Curt; Sturkell, Erik; Ormö, Jens; Siljeström, Sandra; van Zuilen, Mark; Bengtson, Stefan

    2013-01-01

    Impacts are common geologic features on the terrestrial planets throughout the solar system, and on at least Earth and Mars impacts have induced hydrothermal convection. Impact-generated hydrothermal systems have been suggested to possess the same life supporting capability as hydrothermal systems associated with volcanic activity. However, evidence of fossil microbial colonization in impact-generated hydrothermal systems is scarce in the literature. Here we report of fossilized microorganisms in association with cavity-grown hydrothermal minerals from the 458?Ma Lockne impact structure, Sweden. Based on morphological characteristics the fossilized microorganisms are interpreted as fungi. We further infer the kerogenization of the microfossils, and thus the life span of the fungi, to be contemporaneous with the hydrothermal activity and migration of hydrocarbons in the system. Our results from the Lockne impact structure show that hydrothermal systems associated with impact structures can support colonization by microbial life. PMID:24336641

  15. Efficiencies of Power Plants Using Hydrothermal Oxidation

    Microsoft Academic Search

    Kazuma Hirosaka; Korakot Yuvamitra; Akira Ishikawa; Tatsuya Hasegawa

    2008-01-01

    Wet biomass is hard to handle as a fuel for power plants because it contains high moisture and its drying process needs more energy input than it produces. Hydrothermal oxidation could be one of the promising technologies to overcome this problem because this process does not need drying process at all. We focus on recovery of thermal energy produced by

  16. DRILLED HYDROTHERMAL ENERGY Drilling for seawater

    E-print Network

    Water Desalination Fuel Production Waste Water Treatment Increased CO2 Absorbtion Agriculture & Mari) of cold water pipe WAS LOST 3 TIMES before demonstrating power generation #12;DRILLED HYDROTHERMAL ENERGY BACKGROUND After a 2006 earthquake on the Big Island The NELHA cold water pipe cracked allowing warm water

  17. The Discovery of Marine Hydrothermal Vents

    NSDL National Science Digital Library

    OceanLink

    As part of OceanLink, a website dedicated to ocean education, this site gives an overview of the discovery, geology and ecology of marine hydrothermal vents. The site also provides a menu of links to access other OceanLink pages for further ocean-related information.

  18. Hydrothermal gasification of biomass and organic wastes

    Microsoft Academic Search

    H. Schmieder; J. Abeln; N. Boukis; E. Dinjus; A. Kruse; M. Kluth; G. Petrich; E. Sadri; M. Schacht

    2000-01-01

    Wet biomass and organic wastes can be efficiently gasified under hydrothermal conditions to produce a hydrogen rich fuel gas. New experiments in two tubular flow reactors and in two batch autoclaves with carbohydrates, with aromatic compounds, with glycine as a model compound for proteins and with real biomass are reported for different residence times, temperatures and pressures. It was found

  19. Hydrothermal carbonization of municipal waste streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydrothermal carbonization (HTC) is a novel thermal conversion process that can be used to convert municipal waste streams into sterilized, value-added hydrochar. HTC has been mostly applied and studied on a limited number of feedstocks, ranging from pure substances to slightly more complex biomass ...

  20. Hydrothermal alteration and magnetic properties of rocks in the Carolina de Michilla stratabound copper district, northern Chile

    NASA Astrophysics Data System (ADS)

    Townley, Brian; Roperch, Pierrick; Oliveros, Verónica; Tassara, Andres; Arriagada, César

    2007-10-01

    In the Carolina de Michilla district, northern Chile, stratabound copper mineralization is hosted by Jurassic volcanic rocks along the trace of the Atacama fault system. In this study, we present the overall effects of hydrothermal alteration on the magnetic properties of rocks in this district. Two types of metasomatic alteration associations occur, one of regional extent and the other of local hydrothermal alteration associated with copper mineralization (e.g., Lince Estefanía Susana). Regional alteration is interpreted as a low-grade “propylitic association” characterized by an epidote chlorite smectite titanite albite quartz calcite association. The local hydrothermal alteration is characterized broadly by a quartz albite epidote chlorite calcite mineral assemblage. The most pervasive alteration mineral is albite, followed by epidote and, locally, actinolite. These minerals contrast sharply against host rock minerals such as chlorite, calcite, zeolite, prehnite, and pumpellyite, but alteration is constrained to mineralized bodies as narrow and low contrast alteration halos that go outwards from actinolite albite to epidote albite, to epidote chlorite, and finally to chlorite. Hydrothermal alteration minerals, compared to regional alteration minerals, show iron-rich epidotes, a lower chlorite content of the chlorite smectite series, and a nearly total albite replacement of plagioclase in the mineralized zones. Opaque minerals associated with regional alteration are magnetite and maghemite, and those associated to hydrothermal alteration are magnetite, hematite, and copper sulphides. We present paleomagnetic results from nine sites in the Michilla district and from drill cores from two mines. Local effects of hydrothermal alteration on the original magnetic mineralogy indicate similar characteristics and mineralogy, except for an increase of hematite that is spatially associated with the Cu sulphide breccias with low magnetic susceptibilities. Results indicate that it is impossible to magnetically differentiate mineralized bodies from unmineralized lavas, except for pyrite-rich hydrothermal breccias. In conclusion, for stratabound copper deposits of the Michilla type, the overall effect of hydrothermal alteration on the paleomagnetic properties of rocks is of low contrast, not clearly discernable even at a small scale. From an exploration point of view, magnetic exploration surveys should not discern mineralized bodies of Cu sulphide breccias except in detailed ground surveys due to the small size of contrasting bodies. Unoriented drill cores with primary ore mineralization record a characteristic remanent magnetization of reverse polarity. Taking into account the azimuth and dip of the drill cores, we were able to compare the magnetization of the mineralized bodies with the characteristic directions from sites drilled in situ from Late Jurassic Early Cretaceous intrusives mostly. The characteristic direction recorded by the Pluton Viera is similar to the magnetization of the ore bodies of the Estefania mine. If copper mineralization mostly postdates the tilt of the volcanic flows, the low paleomagnetic inclinations suggest an age for the mineralization near 145 Ma, the time of the lowest paleolatitude for the South American plate during the Mesozoic.

  1. Experimental constraints on hydrothermal activities in Enceladus

    NASA Astrophysics Data System (ADS)

    Sekine, Y.; Shibuya, T.; Suzuki, K.; Kuwatani, T.

    2012-12-01

    One of the most remarkable findings by the Cassini-Huygens mission is perhaps water-rich plumes erupting from the south-pole region of Enceladus [1]. Given such geological activity and the detection of sodium salts in the plume, the interior of Enceladus is highly likely to contain an interior ocean interacting with the rock core [2]. A primary question regarding astrobiology and planetary science is whether Enceladus has (or had) hydrothermal activities in the interior ocean. Because N2 might be formed by thermal dissociation of primordial NH3 [3], the presence of N2 in the plume may be a possible indicator for the presence of hydrothermal activities in Enceladus. However, the Cassini UVIS revealed that the plumes do not contain large amounts of N2 [4]. Although these observations may not support the presence of hydrothermal activities, whether NH3 dissociation proceeds strongly depends on the kinetics of hydrothermal reactions and interactions with the rock components, which remain largely unknown. Furthermore, the Cassini CDA recently showed that small amounts of SiO2 might have been included in the plume dusts [5]. Formation of amorphous SiO2 usually occurs when high-temperature and/or high-pH solution with high concentrations of dissolved SiO2 cools and/or is neutralized. Thus, the presence of SiO2 in the plume dusts may suggest the presence of a temperature and/or pH gradient in the ocean. However, no laboratory experiments have investigated what processes control pH and SiO2 concentrations in hydrothermal fluids possibly existing in Enceladus. Here, we show the results of laboratory experiments simulating hydrothermal systems on Enceladus. As the initial conditions, we used both aqueous solution of high concentrations (0.01-2%) of NH3 and NaHCO3 and powdered olivine as an analog for the rock components. Our experimental results show that formation of N2 from NH3 is kinetically and thermodynamically inhibited even under high temperature conditions (< 400°C). This is because NH3 decomposition proceeds inefficiently due to efficient H2 production via serpentinization. Our experimental results also suggest that SiO2 concentration dissolved in hydrothermal fluids simulating Enceladus' condition would be buffered by the serpentine-brucite system. The presence of NH3 in the hydrothermal conditions keeps pH of the solution high (pH 9-11). We suggest that under such conditions, SiO2 concentrations in the fluids would be 0.1 mmol/L or less for temperature < 350°C. Given the SiO2 solubility of 1-10 mmol/L at 0°C and pH 9-11, direct formation of amorphous SiO2 would not occur in Enceladus' hydrothermal systems. To produce amorphous SiO2, large-scale hydrothermal activities and subsequent concentration of dissolved SiO2 in the ocean (due to freezing and/or evaporation of liquid water) would be required, which is consistent with high concentrations of radiogenic Ar and sodium salts in the plume [2, 6]. [1] Porco et al., Science 311, 1393 (2006). [2] Postberg et al., Nature 459, 1098 (2009). [3] Matson et al., Icarus 187, 569 (2007). [4] Hansen t al., Geophs. Res. Lett. 38, L11202 (2011). [5] Hsu et al., EOS Trans. AGU, (2010). [6] Waite et al., Nature 460, 487 (2009).

  2. Hydrothermal systems in small ocean planets.

    PubMed

    Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael

    2007-12-01

    We examine means for driving hydrothermal activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of hydrothermal system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of hydrothermal activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive hydrothermal fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive hydrothermal circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1). PMID:18163874

  3. Plasma Endothelin1 Release in Normal and Varicose Saphenous Veins

    Microsoft Academic Search

    Roberto Antonio Mangiafico; Lorenzo Salvatore Malatino; Maurizio Santonocito; Rosario Sebastiano Spada; Francesco Antonio Benedetto

    1997-01-01

    The aim of the study was to investigate the release of endothelin-1 (ET-1) in normal and varicose saphenous veins at baseline and after venous stasis test. Ten patients (eight women and two men, mean age 43 ±4) with primarily varicose great saphenous veins and ten controls (eight women and two men, mean age 42 ±6) were recruited. After 30 minutes

  4. Neurovascular Compression of the Common Peroneal Nerve by Varicose Veins

    Microsoft Academic Search

    N Yamamoto; K Koyano

    2004-01-01

    Compression of the common peroneal nerve occurs sometimes, but compression caused by varicose veins has not been reported before. We report a case of common peroneal nerve compression syndrome which was confirmed and treated surgically. A 63-year-old woman complained of paræsthesia on the lateral aspect of the right leg, which was worse in the evening. A primary varicose vein arising

  5. Design and implementation of a contactless palm vein recognition system

    Microsoft Academic Search

    Goh Kah Ong Michael; Tee Connie; Lau Siong Hoe; Andrew Teoh Beng Jin

    2010-01-01

    This paper presents an innovative contactless palm vein recognition system. We design a hand sensor that could capture the palm vein image using low-resolution web camera. The design of the sensor is simple and low-cost, and we do not need to install specialized infrared sensor. We allow subjects to position their hands freely above the sensor and they can move

  6. Persistence of a single pulmonary vein in a child.

    PubMed

    Mainard, L; Hoeffel, J C; Worms, A M; Marcon, F

    1992-01-01

    Persistence of a single pulmonary vein with normal pulmonary venous return is a rape and unusual radiographic finding. We report such a case with the venous opacity partially visible on the right border of the heart on a plain frontal chest film. MRI showed beautifully the pulmonary vein and can now replace angiocardiography. PMID:1603604

  7. Endoscopic vein harvesting with the aid of carbon dioxide insufflation

    Microsoft Academic Search

    Malcolm J. R Dalrymple-Hay; Aiman Alzetani; Robert Costa; Sunil K Ohri

    2001-01-01

    Endoscopic harvesting of the long saphenous vein has been introduced to decrease the morbidity of obtaining venous conduit for coronary artery bypass grafting. Herein is described an endoscopic method using carbon dioxide insufflation into the tissues around the vein. This has several advantages; improved vision, no physical retraction required, easier development of tissue planes, and improved hemostasis.

  8. Exercise-Induced Deep Vein Thrombosis of the Upper Extremity

    Microsoft Academic Search

    Leonardo R. Brandão; Suzan Williams; Walter H. A. Kahr; Clodagh Ryan; Michael Temple; Anthony K.C. Chan

    2006-01-01

    Paget-Schroetter syndrome or effort-related upper extremity deep vein thrombosis is a rare condition that usually afflicts young healthy individuals, most commonly males. The cause is multifactorial but almost always involves extrinsic compression of the subclavian vein at the thoracic inlet, causing venous stenosis from repetitive trauma. The diagnosis of this condition may be difficult, and its delay may contribute to

  9. Tissue Fibrinolytic Activity in Different Types of Varicose Veins

    Microsoft Academic Search

    Viola Hach; Monika Fink; Norbert Blees; Inge Scharrer

    1986-01-01

    The fibrinolytic activity of the venous wall was investigated by using Todd's technique 1 in 92 patients with different types of varicosis.A control group consisted of 19 patients with apparently normal superficial veins who had had a saphenectomy prior to an aortocoronary bypass operation. Fibrinolytic activity was mainly localized in the adventitia of varicose and nor mal veins. It significantly

  10. Green Veining: Landscape Determinants of Biodiversity in European Agricultural Landscapes

    Microsoft Academic Search

    Carla J. Grashof-Bokdam; Frank van Langevelde

    2005-01-01

    Many semi-natural landscape elements, the so-called green veining, are disappearing from the intensively used agricultural landscapes of Europe. In order to develop or restore biodiversity in these networks, it is necessary to quantify the relation between biodiversity and amount, spatial arrangement and management intensity of green veining elements. In this review, we investigate whether biodiversity increases with the amount of

  11. Fossil evidence for Cretaceous escalation in angiosperm leaf vein evolution

    E-print Network

    Bermingham, Eldredge

    Fossil evidence for Cretaceous escalation in angiosperm leaf vein evolution Taylor S. Feilda,1 plants that dominate modern vegetation possess leaf gas exchange potentials that far exceed those of all. Using vein density (DV) measurements of fossil angiosperm leaves, we show that the leaf hydraulic

  12. Subclavian vein repair in patients with an ipsilateral arteriovenous fistula

    Microsoft Academic Search

    Wayne S. Gradman; Paul Bressrnan; J. David Sernaque

    1994-01-01

    Management of subclavian vein occlusive disease in persons with an ipsilateral arteriovenous fistula can be challenging. From July 1991 to May 1993, nine patients underwent direct exploration and repair of an obstructed subclavian vein following medial claviculectomy. Eight patients had polytetrafluoroethylene (PTFE) grafts; one patient had a Brescia-Cimino fistula. Intractable arm edema was the major symptom in five of eight.

  13. Cross-Database Evaluation Using an Open Finger Vein Sensor

    E-print Network

    recognition is a recent biometric ap- plication, which relies on the use of human finger vein pat- terns the vein patterns inside a person's finger [1]. Compared to other biometric modalities such as fingerprint made available in 2002 and logical access for ATMs in 2005 [2]. Nowadays this technology is widely used

  14. Spontaneous rupture of the left common iliac vein.

    PubMed

    Gaschignard, N; Le Paul, Y; Maouni, T; Le Priol, P D

    2000-09-01

    We report a case of spontaneous rupture of the left common iliac vein in a 58-year-old woman. Because of hemorrhagic shock, the intervention had to be performed under emergency circumstances, precluding repair of the external iliac vein, which was ligated. The postoperative course was uneventful. We also review the 17 prior cases found in the literature. PMID:10990565

  15. Endoscopic and traditional saphenous vein harvest: a histologic comparison

    Microsoft Academic Search

    Gary L. Griffith; Keith B. Allen; Bruce F. Waller; David A. Heimansohn; Robert J. Robison; John J. Schier; Carl J. Shaar

    2000-01-01

    Background. Vein trauma after saphenectomy by endoscopic or longitudinal techniques may influence the progression of medial and intimal hyperplasia and ultimately affect graft patency. This study compared the histologic characteristics of saphenous veins after endoscopic and longitudinal harvest.Methods. One hundred seventy patients who underwent elective coronary artery bypass grafting had saphenectomy performed endoscopically (n = 88) or by a longitudinal

  16. Endoscopic versus traditional saphenous vein harvesting: a prospective, randomized trial

    Microsoft Academic Search

    Keith B Allen; Gary L Griffith; David A Heimansohn; Robert J Robison; Robert G Matheny; John J Schier; Edward B Fitzgerald; Carl J Shaar

    1998-01-01

    Background. Saphenous vein harvested with a traditional longitudinal technique often results in leg wound complications. An alternative endoscopic harvest technique may decrease these complications.Methods. One hundred twelve patients scheduled for elective coronary artery bypass grafting were prospectively randomized to have vein harvested using either an endoscopic (group A, n = 54) or traditional technique (group B, n = 58). Groups

  17. Sphincters of the pulmonary veins in man, and their significance

    Microsoft Academic Search

    L. L. Kapuller; M. Lo Shik

    1961-01-01

    Pressure curves in the pulmonary vein and in the left auricle were recorded in patients with stenosis of the left atrioventricular valve before and after mitral valvotomy. The curves showed that the sphincters of the pulmonary veins may fail when the mean pressure in the left auricle exceeds 20 mm Hg. Normally, by blocking the reverse flow, the sphincters protect

  18. Investigating fossil hydrothermal systems by means of fluid inclusions and stable isotopes in banded travertine: an example from Castelnuovo dell'Abate (southern Tuscany, Italy)

    NASA Astrophysics Data System (ADS)

    Rimondi, Valentina; Costagliola, Pilario; Ruggieri, Giovanni; Benvenuti, Marco; Boschi, Chiara; Brogi, Andrea; Capezzuoli, Enrico; Morelli, Guia; Gasparon, Massimo; Liotta, Domenico

    2015-05-01

    Southern Tuscany (Italy) hosts geothermal anomalies with associated widespread CO2 gas-rich manifestations and active travertine-deposing thermal springs. Geothermal anomalies have been active since the Late Miocene and have led to the formation of widespread Late Miocene-Pleistocene travertine deposits and meso- and epithermal mineralizations. This study investigates the travertine deposit exposed in the Castelnuovo dell'Abate area of southern Tuscany. Here, a fissure-ridge type travertine deposit and its feeding conduits, currently filled with banded calcite veins (i.e. banded travertine), represent a spectacular example of fossil hydrothermal circulation in the peripheral area of the exploited Monte Amiata geothermal field. The Castelnuovo dell'Abate travertine deposit and associated calcite veins were analysed to establish the characteristics of the parent hydrothermal fluids, and the age of this circulation. The focus of the study was on fluid inclusions, rarely considered in travertine studies, but able to provide direct information on the physico-chemical characteristics of the original fluid. Uranium-thorium geochronological data provided further constraints on the: (1) age of tectonic activity; (2) age of the hydrothermal circulation; and (3) evolution of the Monte Amiata geothermal anomaly. Results indicate that brittle deformation (NW- and SE-trending normal to oblique-slip faults) was active during at least the Middle Pleistocene and controlled a hydrothermal circulation mainly characterized by fluids of meteoric origin, and as old as 300-350 ka. This is the oldest circulation documented to date in the Monte Amiata area. The fluid chemical composition is comparable to that of fluids currently exploited in the shallow reservoir of the Monte Amiata geothermal field, therefore suggesting that fluid composition has not changed substantially over time. These fluids, however, have cooled by about 70 °C in the last 300-350 ka, corresponding to a cooling rate of the Monte Amiata geothermal area of about 20 °C 100 ka-1.

  19. Complete hydrothermal re-equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001 Ma minimum age of impact?

    NASA Astrophysics Data System (ADS)

    ScherstéN, Anders; Garde, Adam A.

    2013-08-01

    Zircon in five samples of variably comminuted, melted, and hydrothermally altered orthogneiss from the Maniitsoq structure of southern West Greenland yield a weighted mean 207Pb/206Pb age of 3000.9 ± 1.9 Ma (ion probe data, n = 37). The age data constitute a rare example of pervasive and nearly complete isotopic resetting of zircon during a regional hydrothermal event. Many zircon grains are homogeneous or display weak flame-like patterns in backscattered electron images. Other grains show complex internal textures, where homogeneous, high-U fronts commonly cut across relict igneous-type oscillatory zonation. Inclusions of quartz, plagioclase, mica, and other Al ± Na ± Ca ± Fe-bearing silicates are very common. In two samples, selective replacement of zircon with baddeleyite occurs along concentric zones with relict igneous zonation, and as specks a few microns large within recrystallized, high-U areas. We interpret the 3000.9 ± 1.9 Ma date as the minimum age of the recently proposed impact structure at Maniitsoq. The great geographical extent and intensity of the hydrothermal event suggest massive invasion of water into the currently exposed crust, implying that the age of the hydrothermal alteration would closely approximate the age of the proposed impact at Maniitsoq. At the western margin of the Taserssuaq tonalite complex, which postdates the Maniitsoq event, a 207Pb/206Pb mean age of 2994.6 ± 3.4 Ma obtained from zircon has mostly retained igneous-type oscillatory zonation. A subsequent thermal event at approximately 2975 Ma is recorded in several samples by zircon with baddeleyite replacement textures.

  20. Fluid inclusion gas studies, carrock fell tungsten deposit, england: implications for regional exploration

    Microsoft Academic Search

    T. J. Shepherd; P. Waters

    1984-01-01

    A fluid inclusion investigation of the Carrock Fell tungsten deposit, Northern England, confirms that the quartz-wolframite-scheelite veins associated with the Caledonian Skiddaw Granite are almost exclusively related to an exocontact hydrothermal system developed at the margin of a local cupola. Fluid circulation, as defined by the spatial variation in temperature and H2O\\/CO2 ratios for inclusions in vein quartz, reveals a

  1. Hydrothermal Activity on ultraslow Spreading Ridge: new hydrothermal fields found on the Southwest Indian ridge

    NASA Astrophysics Data System (ADS)

    Tao, C.; Li, H.; Deng, X.; Lei, J.; Wang, Y.; Zhang, K.; Zhou, J.; Liu, W.

    2014-12-01

    Ultraslow spreading ridge makes up about 25% of global mid-ocean ridge length. Previous studies believed that hydrothermal activity is not widespread on the ultraslow spreading ridge owing to lower magma supply. Southwest Indian ridge (SWIR) with the spreading rate between 1.2cm/a to 1.4cm/a, represents the ultraslow spreading ridge. In 2007, Chinese Cruise (CC) 19th discovered the Dragon Flag deposit (DFD) on the SWIR, which is the first active hydrothermal field found on the ultraslow spreading ridge. In recent years, over 10 hydrothermal fields have been found on the SWIR between Indomed and Gallieni transform faults by the Chinese team. Tao et al. (2012) implied that the segment sections with excess heat from enhanced magmatism and suitable crustal permeability along slow and ultraslow ridges might be the most promising areas for searching for hydrothermal activities. In 2014, CC 30thdiscovered five hydrothermal fields and several hydrothermal anomalies on the SWIR. Dragon Horn Area (DHA). The DHA is located on the southern of segment 27 SWIR, with an area of about 400 km2. The geophysical studies indicated that the DHA belongs to the oceanic core complex (OCC), which is widespread on the slow spreading ridges (Zhao et al., 2013). The rocks, such as gabbro, serpentinized peridotite, and consolidated carbonate were collected in the DHA, which provide the direct evidence with the existence of the OCC. However, all rock samples gathered by three TV-grab stations are basalts on the top of the OCC. A hydrothermal anomaly area, centered at 49.66°E?37.80° S with a range of several kms, is detected in the DHA. It is probably comprised of several hydrothermal fields and controlled by a NW fault. New discovery of hydrothermal fields. From January to April 2014, five hydrothermal fields were discovered on the SWIR between 48°E to 50°E during the leg 2&3 of the CC 30th, which are the Su Causeway field (48.6°E, 38.1°S), Bai Causeway field (48.8°E, 37.9 °S), Dragon Well West field (49.6°E, 37.8°S), Dragon Well East field (49.8°E, 37.8°S), and Landing Stage field (51.0°E, 37.5°S), respectively.

  2. Relict hydrothermal zones in the TAG Hydrothermal Field, Mid-Atlantic Ridge 26°N, 45°W

    NASA Astrophysics Data System (ADS)

    Rona, Peter A.; Bogdanov, Yury A.; Gurvich, Evengy G.; Rimski-Korsakov, Nick A.; Sagalevitch, Anatoly M.; Hannington, Mark D.; Thompson, Geoffrey

    1993-06-01

    Two relict hydrothermal zones were delineated between water depths of 3400 and 3500 m at the lower part of the east wall of the rift valley of the Mid-Atlantic Ridge in the TAG hydrothermal field using a deep-towed side scan sonar tow and a camera-temperature tow along the northern 3 km of the wall, and a submersible transect. Named the North and MIR relict zones, they are located about 4 km and 2 km northeast, respectively, of the known active high-temperature sulfide mound between water depths of 3625 and 3670 m on the rift valley floor near the base of the east wall. The North zone extends about 2 km along the northern end of the lower east wall. The zone includes two moundlike features up to 30 m high by 200 m in diameter imaged by side scan sonar within a 2-km-long line of discontinuous hydrothermal deposits comprising inactive toppled and standing chimneys, layered material, and patchy dark stains on sediment photographed by the camera-temperature tow. Several other moundlike features were imaged with the side scan sonar outside of the photographic coverage. The MIR relict hydrothermal zone 2 km south of the North zone, named after the MIR submersible used to investigate it, consists of three subzones: (1) a 200-m-wide area of diverse types of hydrothermal materials exposed by normal faulting at its western margin; (2) a 400-m-wide by 700-m-long central area of discrete groups of toppled and standing inactive sulfide chimneys up to 25 m high on a substrate of red metalliferous sediment and carbonate lutite; spires sampled on the highest chimneys are composed of coarse-grained, recrystallized sulfides dominated by pyrite and chalcopyrite which contain the first primary, free gold grains (2-3 ?m diameter) found at a hydrothermal site on a mid-ocean ridge; and (3) a 150-m-wide hummocky area of layered hydrothermal material with the appearance of low temperature precipitates and carbonate lutite with patchy dark stains at its eastern margin. The active sulfide mound, the North zone, and the MIR zone are each located on the fractured western margins of gentle, dome-shaped areas of pillow flows typically 500 m in diameter interpreted as summits of volcanic centers that may have supplied heat to drive adjacent hydrothermal activity. The distribution and size of the active and inactive hydrothermal zones of the TAG field, the chronology, and the characteristics of relict samples recovered indicate a history of at least 100 ×103 years of high-temperature hydrothermal episodes with multiple overprinting stages of mineralization accompanied by alteration.

  3. Quartz microbalance device for transfer into ultrahigh vacuum systems

    SciTech Connect

    Stavale, F.; Achete, C. A. [Divisao de Metrologia de Materiais (DIMAT), Inmetro, CEP 25250-020, Xerem, Duque de Caxias, Rio de Janeiro (Brazil); Programa de Engenharia Metalurgica e de Materiais (PEMM), Universidade Federal do Rio de Janeiro, Cx. Postal 68505, CEP 21945-970, Rio de Janeiro (Brazil); Niehus, H. [Divisao de Metrologia de Materiais (DIMAT), Inmetro, CEP 25250-020, Xerem, Duque de Caxias, Rio de Janeiro (Brazil); Institut fuer Physik, Humboldt Universitaet zu Berlin, Newtonstrasse 15, Berlin 12489 (Germany)

    2008-10-15

    An uncomplicated quartz microbalance device has been developed which is transferable into ultrahigh vacuum (UHV) systems. The device is extremely useful for flux calibration of different kinds of material evaporators. Mounted on a commercial specimen holder, the device allows fast quartz microbalance transfer into the UHV and subsequent positioning exactly to the sample location where subsequent thin film deposition experiments shall be carried out. After backtransfer into an UHV sample stage, the manipulator may be loaded in situ with the specimen suited for the experiment. The microbalance device capability is demonstrated for monolayer and submonolayer vanadium depositions with an achieved calibration sensitivity of less the 0.001 ML coverage.

  4. The relationship of Olpidium brassicae (Wor.) Dang. to the big-vein disease of lettuce

    Microsoft Academic Search

    P. R. Fry

    1958-01-01

    Inoculation of lettuce with tobacco-necrosis virus isolated from big-vein plants did not cause big-vein symptoms.Olpidium brassicae was always found in roots of lettuce grown in big-vein-infected soil but not in two gardens where big vein did not occur.Olpidium resting spores were sedimented from big-vein root sap by low-speed centrifuging. Inoculation of lettuce with resuspended sediment produced big-vein symptoms while inoculation

  5. Design of a clinical vein contrast enhancing projector

    NASA Astrophysics Data System (ADS)

    Zeman, Herbert D.; Lovhoiden, Gunnar; Deshmukh, Harshal

    2001-06-01

    A clinical study has been initiated to compare an experimental IR device, the Vein Contrast Enhancer (VCE), with standard techniques for finding veins for venipuncture. The aims of this proposal are (1) to evaluate the performance of the VCE in a clinical setting, specifically by comparing its sensitivity of detection with existing vein-finding techniques used by experienced nurses or phlebotomists, (2) to study its usefulness in subjects who are obese, who have difficult venous access or thrombosed veins, or whose veins are not visible or difficult to palpate, and (3) to show that it performs as well on subjects with darkly pigmented skin as on subjects with lightly pigmented skin. The VCE will first be studied in adult subjects, and then in pediatric subjects.

  6. Balloon-Occluded Retrograde Transvenous Obliteration of Gastric Varix Draining via the Left Inferior Phrenic Vein into the Left Hepatic Vein

    SciTech Connect

    Ibukuro, Kenji; Mori, Koichi; Tsukiyama, Toshitaka; Inoue, Yoshihiro [Department of Radiology, Mitsui Memorial Hospital, 1-Kanda Izumicho, Chiyoda-ku, Tokyo 101-8643 (Japan); Iwamoto, Yukako; Tagawa, Kazumi [Department of Gastroenterology, Mitsui Memorial Hospital, 1-Kanda Izumicho, Chiyoda-ku, Tokyo 101-8643 (Japan)

    1999-09-15

    We encountered a patient with gastric varix draining not via the usual left suprarenal vein but via the left inferior phrenic vein joining the left hepatic vein. Transfemoral balloon-occluded retrograde transvenous obliteration (BRTO) of the varix was performed under balloon occlusion of the left inferior phrenic vein via the left hepatic vein and retrograde injection of the sclerosing agent (5% of ethanolamine oleate) into the gastric varix. Disappearance of the gastric varix was confirmed on endoscopic examination 2 months later.

  7. [Effort thrombosis of the right subclavian vein].

    PubMed

    Tamar, Michael; Farah, Raymond

    2012-11-01

    This case report illustrates a primary upper extremity DVT of the right subclavian vein in an otherwise healthy young male. The pathogenesis of primary upper extremity DVT may be anatomical, such as thoracic outlet syndrome, vascular microtrauma e.g. effort thrombosis, or both. After examining the patient's clinical presentation and imaging results, a diagnosis of effort thrombosis, or "Paget-Schroetter syndrome" was made. Due to the clear insulting factor, the mild clinical presentation, and the fast response to anti-coagulant treatment, a conservative treatment was followed, which included anti-coagulation and close follow-up, as advised by the American College of Chest Physician's evidence-based clinical practice guidelines. PMID:23367728

  8. NET impact on deep vein thrombosis

    PubMed Central

    Fuchs, Tobias A.; Brill, Alexander; Wagner, Denisa D.

    2012-01-01

    Deep vein thrombosis (DVT) is a major health problem that requires improved prophylaxis and treatment. Inflammatory conditions such as infection, cancer and autoimmune diseases are risk factors for DVT. We and others have recently shown that extracellular DNA fibers produced in inflammation and known as neutrophil extracellular traps (NETs) contribute to experimental DVT. NETs stimulate thrombus formation and coagulation and are abundant in thrombi in animal models of DVT. It appears that, in addition to fibrin and VWF, NETs represent a third thrombus scaffold. Here we review how NETs stimulate thrombosis and discuss known and potential interactions of NETs with endothelium, platelets, red blood cells, coagulation factors and how NETs could influence thrombolysis. We propose that drugs which inhibit NET formation or facilitate NET degradation may prevent or treat DVT. PMID:22652600

  9. Repair of peripheral nerve with vein wrapping*

    PubMed Central

    LEUZZI, S.; ARMENIO, A.; LEONE, L.; DE SANTIS, V.; DI TURI, A.; ANNOSCIA, P.; BUFANO, L.; PASCONE, M.

    2014-01-01

    Objective The post–traumatic neuro-anastomosis must be protected from the surrounding environment. This barrier must be biologically inert, biodegradable, not compressing but protecting the nerve. Formation of painful neuroma is one of the major issues with neuro-anastomosis; currently there is no consensus on post-repair neuroma prevention. Aim of this study is to evaluate the efficacy of neuroanastomosis performed with venous sheath to reduce painful neuromas formation, improve the electrical conductivity of the repaired nerve, and reduce the discrepancies of the sectioned nerve stumps. Patients and methods From a trauma population of 320 patients treated in a single centre between January 2008 and December 2011, twenty-six patients were identified as having an injury to at least one of the peripheral nerves of the arm and enrolled in the study. Patients were divided into two groups. In the group A (16 patients) the end-to-end nerve suture was wrapped in a vein sheath and compared with the group B (10 patients) in which a simple end-to-end neurorrhaphy was performed. The venous segment used to cover the nerve micro-suture was harvested from the superficial veins of the forearm. The parameters analyzed were: functional recovery of motor nerves, sensitivity and pain. Results Average follow-up was 14 months (range: 12–24 months). The group A showed a more rapid motor and sensory recovery and a reduction of the painful symptoms compared to the control group (B). Conclusions The Authors demonstrated that, in their experience, the venous sheath provides a valid solution to avoid the dispersion of the nerve fibres, to prevent adherent scars and painful neuromas formation. Moreover it can compensate the different size of two nerve stumps, allowing, thereby, a more rapid functional and sensitive recovery without expensive devices. PMID:24841688

  10. Central retinal vein occlusion and pseudoexfoliation syndrome

    PubMed Central

    Karagiannis, Dimitrios; Kontadakis, Georgios A; Klados, Nektarios E; Tsoumpris, Ioannis; Kandarakis, Artemios S; Parikakis, Efstratios A; Georgalas, Ilias; Tsilimbaris, Miltiadis K

    2015-01-01

    Purpose The purpose of this study was to investigate the existence of pseudoexfoliation syndrome (PXF) as a risk factor for the development of central retinal vein occlusion (CRVO). Methods This was a retrospective, comparative study of the prevalence of pseudoexfoliation in three groups of patients: 48 patients with CRVO, 164 patients with branch retinal vein occlusion (BRVO), and 70 control patients (70 eyes). All patients were phakic and had no previous diagnosis of glaucoma. Patients were matched in terms of age and systemic hypertension. All patients had normal intraocular pressure (IOP) at presentation (defined as less than or equal to 21 mmHg). Results In the CRVO group, 14 out of 48 patients were diagnosed as having PXF (29.17%). In the BRVO group, 14 out of 164 patients had PXF (8.5%), and in the control group, six out of 70 patients had PXF (8.6%). Differences of percentage between groups were statistically significant (P<0.001, ?2 test). When comparing patient subgroup with ischemic CRVO with subgroup with non-ischemic CRVO, we found that in the ischemic CRVO group, 13 out of 27 patients were diagnosed as having PXF (48.15%), and in the non-ischemic CRVO group, one out of 21 patients was diagnosed as having PXF (4.7%; P<0.001, ?2 test). The relative odds of having CRVO in patients with PXF versus patients without PXF were 4.406 (confidence interval [CI], 2.03–9.54). Conclusion PXF and CRVO, especially ischemic, are strongly associated in our study. Our results indicate that PXF might be an independent factor for CRVO, as it is related with CRVO independently from glaucoma.

  11. An Early Paleozoic orogenic gold belt along the Jiang-Shao Fault, South China: Evidence from fluid inclusions and Rb-Sr dating of quartz in the Huangshan and Pingshui deposits

    NASA Astrophysics Data System (ADS)

    Ni, Pei; Wang, Guo-Guang; Chen, Hui; Xu, Ying-Feng; Guan, Shen-Jin; Pan, Jun-Yi; Li, Lin

    2015-05-01

    There are several gold deposits in the eastern section of the regional Jiang-Shao Fault between the Yangtze and Cathaysia Blocks in South China. Auriferous quartz veins in these deposits are strictly hosted in second-order NE-trending ductile shear zones. The ores generally contain low amounts of sulfide minerals (<5%), with pyrite as the most common sulfide mineral hosting native gold. Detailed fluid inclusion work and Rb-Sr dating were conducted on the auriferous quartz veins from the Pingshui and Huangshan deposits. H2O-CO2 inclusions (type I) and aqueous inclusions (type II) ubiquitously coexist in the main mineralization stage veins in the Huangshan and Pingshui deposits. Type I and II inclusions in the Huangshan deposit have similar homogenization temperatures at 214-282 °C, but different salinities with 1.2-6.0 and 2.7-8.7 wt.% NaCl equivalent, respectively. In the gold orebodies from the Pingshui deposit, type I and II inclusions also have similar homogenization temperatures ranging from 236 to 304 °C, but different salinities ranging from 1.2 to 6.4 and from 3.2 to 9.8 wt.% NaCl equivalent, respectively. Fluid inclusion observations and microthermometric results show that the ore fluids are low salinity and CO2-rich. Petrography and microthermometric results of fluid inclusions suggest that extensive fluid immiscibility occurred during the gold mineralization stage. Rb-Sr dating of quartz-hosted fluid inclusions (ca. 450 Ma) for the gold mineralization at Pingshui, combined with previous radiometric age data (ca. 397 Ma) of gold mineralization at Huangshan, suggest that the regional gold mineralization was formed in the Early Paleozoic. This study suggests that there is an Early Paleozoic orogenic gold belt in the eastern section of the Jiang-Shao Fault, formed in response to the coeval northward underthrusting of the Cathaysia Block beneath the Yangtze Block during the Caledonian Orogeny in South China.

  12. Evidence for Hydrothermal Vents as "Biogeobatteries" (Invited)

    NASA Astrophysics Data System (ADS)

    Nielsen, M. E.; Girguis, P. R.

    2010-12-01

    Hydrothermal vents are unique systems that play an important role in oceanic biogeochemical cycles. As chemically reduced hydrothermal fluid mixes with cold oxic seawater, minerals precipitate out of solution resulting in chimney structures composed largely of metal sulfides and anhydrite. Pyrite, which is a natural semi-conductor, is the primary sulfide mineral, but other minerals within chimneys are also conductive (e.g. chalcopyrite, wurtzite, and some iron oxides). Sulfide chimneys are also known to host an extensive endolithic microbial community. Accordingly, submarine hydrothermal systems appear to be examples of biogeobatteries, wherein conductive mineral assemblages span naturally occuring redox gradients and enable anaerobic microbes to access oxygen as an oxidant via extracellular electron transfer (or EET). To test this hypothesis, we ran a series of electrochemical laboratory experiments in which pyrite was used as an anode (in a vessel flushed with hydrothermal-like fluid). When placed in continuity with a carbon fiber cathode, pyrite was found to accept and conduct electrons from both abiotic and biological processes (microbial EET). Specifically, electrical current increased 4-fold (5 nA/m2 to 20 nA/m2) in response to inoculation with a slurry prepared from a hydrothermal vent sample. Inspection of the pyrite anode with SEM revealed ubiquitous coverage by microbes. DNA was extracted from the anodes and the inoculum, and was subjected to pyrosequencing to examine prokaryotic diversity. These data suggest that key microbial phylotypes were enriched upon the pyrite, implicating them in EET. In addition, we deployed an in situ experiment based on microbial fuel cell architecture with a graphite anode inserted into a vent wall coupled to a carbon fiber cathode outside the vent. We observed current production over the course of one year, implying microbial EET in situ. Via pyrosequencing, we observed that the microbial community on the anode was significantly enriched in gammaproteobacteria (with respect to the community on an inert substrate deployed in the same vent, which was dominated by epsilonproteobacteria). The observation of electrical current and the enrichment of distinct microbial communities in both laboratory and in situ experiments provide evidence that hydrothermal vents enable microbes capable of EET to access molecular oxygen in the surrounding seawater as an oxidant. This geochemical and microbial phenomenon may influence the chemistry and mineralogy of vent systems, resulting in localized variations in pH that can influence metal mobilization on a global scale.

  13. Multifractal spatial organisation in hydrothermal gold systems of the Archaean Yilgarn craton, Western Australia

    NASA Astrophysics Data System (ADS)

    Munro, Mark; Ord, Alison; Hobbs, Bruce

    2015-04-01

    A range of factors controls the location of hydrothermal alteration and gold mineralisation in the Earth's crust. These include the broad-scale lithospheric architecture, availability of fluid sources, fluid composition and pH, pressure-temperature conditions, microscopic to macroscopic structural development, the distribution of primary lithologies, and the extent of fluid-rock interactions. Consequently, the spatial distribution of alteration and mineralization in hydrothermal systems is complex and often considered highly irregular. However, despite this, do they organize themselves in a configuration that can be documented and quantified? Wavelets, mathematical functions representing wave-like oscillations, are commonly used in digital signals analysis. Wavelet-based multifractal analysis involves incrementally scanning a wavelet across the dataset multiple times (varying its scale) and recording its degree of fit to the signal at each interval. This approach (the wavelet transform modulus maxima method) highlights patterns of self-similarity present in the dataset and addresses the range of scales over which these patterns replicate themselves (expressed by their range in 'fractal dimension'). Focusing on seven gold ore bodies in the Archaean Yilgarn craton of Western Australia, this study investigates whether different aspects of hydrothermal gold systems evolve to organize themselves spatially as multifractals. Four ore bodies were selected from the Sunrise Dam deposit (situated in the Laverton tectonic zone of the Kurnalpi terrane) in addition to the Imperial, Majestic and Salt Creek gold prospects, situated in the Yindarlgooda dome of the Mount Monger goldfield (approximately 40km due east of Kalgoorlie). The Vogue, GQ, Cosmo East and Astro ore bodies at Sunrise Dam were chosen because they exhibit different structural geometries and relationships between gold and associated host-rock alteration styles. Wavelet-based analysis was conducted on 0.5m and 1m resolution down-hole gold assay concentrations, hyperspectral main mineral concentrations, alteration mineralogy composition (sericite) and structural feature (foliation, alteration and veining) intensity within the systems. The aim is to determine whether hydrothermal systems exhibit distinguishing multifractal signatures that may be used to quantify them, and differentiate system size, high-grade from low-grade, 'successful' versus 'unsuccessful', and proximity to mineralisation.

  14. The Influence of Exotic Calcite on the Mechanical Behavior of Quartz Bearing Fault Gouge

    NASA Astrophysics Data System (ADS)

    Carpenter, B. M.; Di Stefano, G.; Collettini, C.

    2014-12-01

    The interseismic recovery of frictional strength is a fundamental part of the seismic cycle. This restrengthening, and related phenomena, plays a key role in determining the stability and mode of tectonic faulting. Recent experimental data has shown that gouge mineralogy has a strong influence on the rate of frictional healing, with calcite-dominated gouges showing the highest rates. Combining these data with widespread observations of calcite as cement or veins in non-carbonate hosted faults, indicates that the presence of calcite within a fault gouge could play an important role in shallow- and mid-crustal earthquakes. We report on laboratory experiments designed to explore the mechanical behavior of quartz/calcite mixtures as a means to better understand the evolution of fault behavior in faults where carbonate materials are present. We sheared mixtures of powdered Carrara marble (>98% CaCO3) and disaggregated Ottawa sand (99.8% SiO2) at constant normal stress of 5 MPa under saturated conditions at room temperature. We performed slide-hold-slide tests, 1-3,000 seconds, and velocity stepping tests, 0.1-1000 ?m/s, to measure the amount of frictional healing and velocity dependence of friction respectively. Small subsets of experiments were conducted at different boundary conditions. Preliminary results show that the presence of calcite in quartz-based fault gouge has a hardening effect, both in overall frictional strength, where the strength of our mixtures increases with increasing calcite content, and in single experiments, where mixtures with low percentages of calcite show a consistent strain-hardening trend. We also observe that the rates of frictional healing and creep relaxation increase with increasing calcite content. Finally, our results show that the addition of as little as 2.5% calcite within a fault gouge results in a 30% increase in the rate of frictional healing, with further increases in calcite content resulting in larger increases in the rate of healing. Combined with our previous work, our results show that the presence of calcite in fault gouge can lead to accelerated frictional healing and velocity-weakening frictional behavior, favoring seismicity at shallow crustal conditions where faults are thought to fail mostly by aseismic creep.

  15. Super eruption environments make for "super" hydrothermal explosions: Extreme hydrothermal explosions in Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Morgan, L. A.; Shanks, W. P.; Pierce, K. L.

    2006-12-01

    Hydrothermal explosions are violent events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments over areas that range from a few meters in diameter up to several kilometers in diameter. Hydrothermal explosions occur where shallow interconnected reservoirs of steam-saturated fluids underlie thermal fields. Sudden reduction in pressure causes the fluids to flash to steam resulting in significant expansion, rock fragmentation, and debris ejection. In Yellowstone, at least 20 large (>100 meters in diameter) hydrothermal explosions have been identified, and the scale of the individual events dwarfs similar features in other hydrothermal and geothermal areas of the world. Large explosions in Yellowstone have occurred over the past 16 ka at an interval of ~1 per every 700 yrs and similar events are likely to occur in the future. Our studies of hydrothermal explosive events indicate: 1) none are associated with magmatic or volcanic events; 2) several have been triggered by seismic events coupled with other processes; 3) lithic clasts and matrix from explosion deposits are extensively altered, indicating long-term, extensive hydrothermal mineralization in areas that were incorporated into the explosion deposit; 4) many lithic clasts in explosion breccia deposits contain evidence of repeated fracturing and cementation; and 4) dimensions of many documented large hydrothermal explosion craters in Yellowstone are similar to the dimensions of currently active geyser basins or thermal areas in Yellowstone. The vast majority of active thermal areas in Yellowstone are characterized by 1) high-temperature hot-water systems in areas of high heat-flow, 2) extensive systems of hot springs, fumaroles, geysers, sinter terraces, mud pots, and, in places, small hydrothermal explosion craters, 3) widespread alteration of host rocks, 4) large areal dimensions (>several 100 m) and 5) intermittent but long-lived activity (40,000 to 300,000 years). Critical requirements for large hydrothermal explosions are an interconnected system of well-developed joints and fractures along which hydrothermal fluids flow and a water-saturated system close to or at boiling temperatures. Important factors are the active deformation of the Yellowstone caldera, active faults and moderate seismicity, high heat flow, climate changes, and regional stresses. Ascending fluids flow along fractures that develop in response to active deformation of the Yellowstone caldera and along edges of impermeable rhyolitic lava flows. Alteration, self sealing, and dissolution further constrain the distribution and development of hydrothermal fields. A partial impermeable cap can contribute to the final over-pressurization. An abrupt drop in pressure initiates steam-flashing and is instantly transmitted through interconnected fractures, resulting in a series of multiple large-scale explosions and excavation of an explosion crater. Strong similarities between large hydrothermal explosion craters and thermal fields in Yellowstone may indicate that catastrophic failures leading to large hydrothermal explosions represent a unique phase in the life cycle of a geyser basin.

  16. Subseafloor Boiling Within the PACMANUS Hydrothermal System Indicated by Anhydrite-Hosted Fluid Inclusions from ODP Leg 193 Cores

    NASA Astrophysics Data System (ADS)

    Vanko, D. A.; Bach, W.; Scott, S. D.; Yeats, C.; Roberts, S.; Beaudoin, Y.

    2001-12-01

    Drilling during Leg 193 was in an area of active hydrothermal venting from dacitic rocks on Pual Ridge in the Manus Basin. All the cored rocks underlying the fresh surficial volcanic rocks are intensively hydrothermally altered. Primary fluid inclusions preserved in anhydrite veins provide unique fluid samples that provide direct evidence on the chemical and physical properties of hydrothermal fluids present beneath the seafloor. Site 1188 is located on Snowcap Knoll, an area of diffuse warm venting at a water depth of ~1645 m. Fluid inclusions have been studied from a coarse anhydrite +/- pyrite vein from ~123 m below the seafloor. The ambient hydrostatic pressure for this sample is calculated to be ~180 bars. The ambient temperature is unknown, but the T measured after 8 days of thermal rebound at a depth of 360 m in this hole was 313° C. Primary fluid inclusions measuring up to 100 ? m across are dominantly two-phase L + V inclusions, yet fluid inclusions with up to three daughter crystals are also observed. The largest daughter crystal is halite, commonly accompanied by a small transparent granular daughter crystal and an even smaller granular opaque crystal. Consequently, optical inspection alone demonstrates the co-occurrence of both hypersaline, multicomponent brines and less saline aqueous fluids. Ice melting temperatures for L+V inclusions vary from -0.1° to -14.5° C, with a strong mode at -2° C, corresponding to a seawater-like salinity. However, the range in Tm(ice) indicates that a significant number contain quite fresh water, and others contain quite saline water. Ice melting temperatures from the multiphase inclusions, measured in the presence of hydrohalite, range from -29.5° to -39.9° C, confirming their hypersaline composition. These data, as well as measured halite dissolution temperatures ranging from 125° to 257° C, indicate salinities of ~30+/-3 wt.% NaCl equivalent. Most two-phase inclusions homogenize to liquid between 191° C and 351° C. Two very low-salinity inclusions homogenize by critical behavior at 372° C and 385° C. A small subset of inclusions was crushed in oil, whereupon the vapor phase expanded, indicating an internal pressure >1 atm. This indicates the presence of a yet-to-be determined compressible gas component such as CO2 or CH4. During the formation of the anhydrite vein, primary fluid inclusions trapped samples of seawater-like fluid, saline brines, very low-salinity fluid, and mixtures between these three groups. The brines and very low-salinity fluids resulted from fluid phase separation at P>180 bars and T>=380° C.

  17. Tertiary meteoric hydrothermal systems and their relation to ore deposition, northwestern United States and southern British Columbia

    NASA Astrophysics Data System (ADS)

    Criss, Robert E.; Fleck, Robert J.; Taylor, Hugh P., Jr.

    1991-07-01

    Tertiary meteoric hydrothermal systems have altered the rocks exposed over more than 5 % of the land surface of the northwestern United States and southern British Columbia, including at least 25,000 km2 in Idaho. The systems typically involved convective circulation of fluid derived from ordinary meteoric groundwaters around crystallizing, calc-alkaline, epizonal plutons emplaced into coeval volcanic cover rocks. These individual systems had widely ranging "lifetimes" of 103 to 106 years and operated locally throughout the Cenozoic, although the most profound development of such activity occurred during Eocene time. Individual systems varied in size from a few tens of square kilometers (Yankee Fork, Idaho) or less to several thousand square kilometers (Sawtooth and Castro ring zones, Idaho) Typically, regional propylitization aacompanied the fluid circulation, although the higher-temperature alteration assemblages were developed locally, as were intense alteration effects (e.g., silicification, sericitization, etc.) near some veins and in mining districts. A significant amount, probably 25-50%, of the mineral production and potential in the region is closely related to Tertiary meteoric hydrothermal systems. Oxygen and hydrogen isotopic data clearly demonstrate the close geologic association of meteoric hydrothermal systems and mineralization in (1) the Paleocene, Cu-Zn-Pb-Mn Main Stage mineralization at Butte, Montana; (2) numerous Eocene epithermal deposits principally valued for Au and Ag but also including significant deposits of Cu, Pb, Zn, F, Sb, etc., as at Republic, Washington, and in several mining districts in the Idaho batholith and the Challis volcanic field; (3) several Eocene skarn deposits valued for W (Ima, Idaho) and Cu (Mackay, Idaho); (4) important lead-silver vein and replacement deposits of Tertiary (Bluebell, British Columbia) and of probable Cretaceous and early Tertiary age (Wood River, Idaho); (5) several potentially economic Mo-, Be-, and U-bearing Eocene "porphyry" plutons; and (6) Miocene epithermal deposits, most prominently the Au and Ag bearing veins at Silver City and DeLamar, Idaho, the Hg deposits at the McDermitt caldera, Nevada and Oregon, and at Weiser, Idaho, and Au deposits in the Western Cascade Range and Lake County, Oregon. A close spatial association has been demonstrated between ore deposits and rocks having anomalous ?18O values and low ?D values. The most important deposits are associated with relatively small (generally 5-300 km2) zones of low ?18O values, and they are particularly closely linked with zones of very steep 18O/16O gradients in the altered rocks. These associations hold much promise for the use of ?18O and ?D contour maps in future exploration efforts.

  18. Removal of trace elements in hydrothermal plume at submarine volcanic arc hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Shitashima, K.

    2007-12-01

    On the study of geochemical fluxes of trace elements from the hydrothermal system, it is necessary to collect not only samples by the hydro-cast from surface ship and fluid samples using a submersible but also temporally and spatially continuous samples ranging from a fluid to a hydrothermal plume. For that purpose, the sampling method along the diluting and rising plume just after erupting from a hydrothermal vent is effective. The mini CTDT-RMS was installed onto the submersible. The hydrothermal plume samples were collected with monitoring the anomalies of temperature and turbidity by taking the distance from the hydrothermal vent gradually. Unfiltered sample for total (particulate + dissolved) trace element concentration and filtered sample for dissolved trace element concentration were analyzed on land. In V, Ni, Cu, Mo, Cd, Pb and Zn, particulate form was predominant in the fluid. The elements that are easy to form a sulfide such as Cu, Cd and Pb were removed as a sulfide precipitate from the fluid before erupting to the deep ocean. Therefore, the concentration of these trace elements in the hydrothermal plume showed superiority of a dissolved form, and was slightly high or same concentration in the deep ocean. The concentration of Fe in the fluid was extremely higher (500 - 100,000 times) than that in the deep ocean, and showed a fifty-fifty partition between dissolved form and particulate form. In the hydrothermal plume, Fe formed hydroxide mainly and was removed gradually from the plume as a particulate form in dilution and diffusion process of the plume. These hydroxides may play a role of the precipitant that coprecipitate with absorbing the other trace elements. Because Mn is hard to deposit as a sulfide, dissolved form was predominant in the fluid and Mn showed extreme high concentration same as Fe. Mn was discharged to the deep ocean as a dissolved form and removed from the plume as an oxide with increasing the particulate form gradually in dilution and diffusion process of the plume. In addition, existence of an organic trace element as one of a chemical species of dissolved form was confirmed in the hydrothermal plume, and the relationship between the hydrothermal ecosystem and the organic trace elements is very interesting.

  19. Interaction between graphene oxide nanoparticles and quartz sand

    NASA Astrophysics Data System (ADS)

    Sotirelis, Nikolaos P.; Chrysikopoulos, Constantinos V.

    2015-04-01

    In this study, the influence of pH, ionic strength (IS), and temperature on graphene oxide (GO) nanoparticles adsorption onto quartz sand were investigated. Batch experiments were conducted at three controlled temperatures (4, 12, and 25 °C) in solutions with different pH values (pH=4, 7, and 10), and ionic strengths (IS=1.4, 6.4, and 21.4 mM), under static and dynamic conditions. The surface properties of GO nanoparticles and quartz sand were evaluated by electrophoretic mobility measurements. Derjaguin-Landau-Verwey-Overbeek (DLVO), and extended-DLVO (XDLVO) potential energy profiles were constructed for the experimental conditions, using measured zeta potentials. The experimental results shown that GO nanoparticles were very stable under the experimental conditions. Both temperature and pH did not play a significant role in the adsorption of GO nanoparticles onto quartz sand. In contrast, IS was shown to influence adsorption. Increasing the IS, dramatically increased. The adsorption of GO particles onto quartz sand increased dramatically with increasing IS, mainly due to secondary-minimum deposition, as indicated by the XDLVO interaction energy profiles. Furthermore, the experimental data were fitted nicely with a Langmuir type sorption isotherm, and the adsorption kinetics were satisfactorily described with a pseudo-second-order model.