Vein Material Research Articles

HYPOGENE Ba-RICH TODOROKITE AND ASSOCIATED NANOMETRIC NATIVE SILVER IN THE SAN MIGUEL TENANGO MINING AREA, ZACATLAN, PUEBLA, MEXICO

The San Miguel Tenango area, in the northern part of the State of Puebla, Mexico, is an old, now-abandoned silver mining district worked intermittently since Colonial times until the 1970s. Ores were high in grade, but had a low metallurgical recovery. We characterize the main ore mineral of this mining area, a Ba-rich manganese oxide with associated native silver, to investigate the cause of the low recovery. The ore deposits of this area consist of veins in Mesozoic limestone and shale, and hydrothermal breccias in early Pliocene dacitic volcanic rocks. Because of the present inaccessibility of the mine workings, only one vein was available for sampling. The ore mineral is Ba-rich todorokite with associated native silver, both occurring as cavity fillings. The vein-type ore deposits are related to adjacent early Pliocene dacitic volcanic rocks consisting of ash-fall tuffs, ash flows, volcanic necks, and a volcanic dome. Transmitted- and reflected-light petrography show that todorokite precipitated during the first stage of mineralization in a wide variety of habits. A second stage of mineralization consists of botryoidal to massive oxides and hydroxides of iron, ending with specular hematite. Filling open spaces in minerals of the second stage are minerals of a third stage consisting of irregular masses of pyrite, chalcopyrite, and pentlandite a few μm across. On the basis of this stage, a hypogene origin is assumed for the previous two stages. An XRD analysis of the vein material revealed the presence of todorokite and an amorphous phase, and probably also a hydrous manganese oxide. Semiquantitative analysis made with SEM–EDS and quantitative analysis with EPMA–SEM showed that the cations in both Mn oxide phases are Ag, Mn, Ba, Ca, Zn, K, Na, Mg, Fe, and Cu, with lesser amounts of Ni, Co, Sb, and Au, the absence of Pb being noteworthy. A TEM study corroborates the presence of todorokite and of an amorphous phase of hydrous manganese oxide, and shows a nanometric crystalline phase that corresponds to manganosite. Also, TEM analyses show that Ag occurs as nanometric particles of native silver adsorbed on the external surfaces of todorokite (not in the tunnels of its structure) and of the amorphous phase. In addition, IR analysis confirms the presence of todorokite. We attribute the low recovery of silver to scavenging of the dissolved silver by todorokite during the metallurgical process.

Drosophila melanogaster gene Merlin interacts with the clathrin adaptor protein gene lap

The protein Merlin is involved in the regulation of cell proliferation and differentiation in the eyes and wings of Drosophila and is a homolog of the human protein encoded by the Neurofibromatosis 2 (NF2) gene whose mutations cause auricular nerve tumors. Recent studies show that Merlin and Expanded cooperatively regulate the recycling of membrane receptors, such as the epidermal growth factor receptor (EGFR). By performing a search for potential genetic interactions between Merlin (Mer) and the genes important for vesicular trafficking, we found that ectopic expression in the wing pouch of the clathrin adapter protein Lap involved in clathrin-mediated receptor endocytosis resulted in the formation of extra vein materials. On the one hand, coexpression of wild-type Merlin and lap in the wing pouch restored normal venation, while overexpression of a dominant-negative mutant Mer(DBB) together with lap enhanced ectopic vein formation. Using various constructs with Merlin truncated copies, we showed the C-terminal portion of the Merlin protein to be responsible for the Merlin-lap genetic interaction. Furthermore, we showed that the Merlin and Lap proteins colocalized at the cortex of the wing imaginal disc cells.

Management of Carotid Dacron Patch Infection: A Case Report Using Median Sternotomy for Proximal Common Carotid Artery Control and In Situ Polytetrafluoroethylene Grafting

We report on a 58-year-old male who presented with an enlarging cervical hematoma 3 months following carotid endarterectomy with Dacron patch repair, due to septic disruption of the Dacron patch secondary to presumed infection. The essential features of this case are the control of the proximal common carotid artery gained through a median sternotomy, because the patient was markedly obese with minimal thyromental distance, and the treatment consisting of in situ polytetrafluoroethylene bypass grafting, due to the absence of a suitable autogenous saphenous vein. Median sternotomy is rarely required in case of reintervention for septic false aneurysms and hematomas following carotid endarterectomy but should be considered whenever difficult control of the common carotid artery, when entering the previous cervicotomy, is anticipated. In situ polytetrafluoroethylene grafting can be considered if autogenous vein material is lacking.

Evolving deformation along a transform plate boundary: Example from the Dead Sea Fault in northern Israel

We analyzed geologic structures adjacent to the Dead Sea Fault (DSF) along the margins of the Sinai and Arabian plates in northern Israel in order to investigate the style and sequence of deformation associated with a transform plate boundary. The field area, located between the Hula basin in northern Israel and the Lebanese restraining bend in southern Lebanon, is divided into distinct structural blocks by a series of distributed faults that comprise this approximately N‐S trending section of the DSF. Cretaceous and Tertiary rocks within and adjacent to the structural blocks are folded into broad anticlines and synclines, with more intense localized shortening manifested by tight folds and thrust duplexes. Kinematic analyses of folds, faults, and veins provide evidence for two directions of regional shortening: (1) NW‐SE shortening responsible for the formation of NE‐SW trending fold axes and left‐lateral strike‐slip motion along N‐S trending faults and (2) E‐W shortening as indicated by N‐S trending fold axes, N‐S striking thrust faults, and extensional calcite‐filled veins that strike E‐W. Crosscutting relations and U‐Th ages of the vein material suggest that the E‐W phase of transform‐normal shortening represents the most recent and presently active phase of deformation. The structural analysis provides evidence for the transition from an early (Miocene–lower Pliocene) phase of pure strike‐slip motion to a late (Pleistocene to Recent) phase of convergent strike slip. The latter phase is characterized by strain partitioning, which is manifested by discrete left‐lateral strike‐slip motion across weak N‐S faults and the development of a fold‐thrust belt in response to transform‐normal shortening. Analogous to the strain partitioning observed in southern California, we suggest that blind thrust faults adjacent to the DSF in the study area may pose a seismic risk to populations in northern Israel and southern Lebanon.

Arterielle Gefäßverletzungen im Rahmen offener Frakturen – Management und Versorgung

Vascular injuries are an uncommon finding. In times of peace vascular injuries occur in approximately 1-4 % during traffic accidents. Especially challenging is the treatment of open fractures combined with arterial lesions. These fractures are usually accompanied with severe soft tissue damage and injuries to neurological structures. The overall prognosis of these trauma patients is dependent on fast and sufficient diagnostics and therapy. In particular, for unstable patients time-consuming diagnostics can be dispensed and a primarily operative therapy should be targeted. Vascular reconstruction by direct suture is sometimes only possible with interposition and should be the primary goal. Interposition should be performed with autologous vein material because of the high risk of infection. Here we demonstrate on the basis of our patients the interdisciplinary -management of such trauma patients in our hospital.

Initial Experience with a New Method of External Polyester Scaffolding for Infrainguinal Vein Grafts

This study aims to evaluate the feasibility of external polyester scaffolding in infrainguinal bypass grafting when available vein material is suboptimal due to varicosity or dilatation. Primary objectives were short-term primary patency, assisted primary patency and secondary patency. Secondary objectives were to assess the rate of graft stenoses, infections and other adverse effects related to the use of external scaffolding. A total of 50 consecutive patients were included in this prospective, multicentre, feasibility study from six centres. The indication for infrainguinal bypass was critical limb ischaemia (64%), severe claudication (34%) or popliteal aneurysm (2%). Indications for the use of the external scaffolding were varicosity of the vein graft, ectatic vein graft or the use of spliced vein grafts with segments of widely differing diameters. Duplex scanning of the graft was done perioperatively and at follow-up visits at 1, 3, 6 and 12 months after operation. Primary patency, assisted primary patency and secondary patency at 6 months were 82.3% (+/-SE 6.2%), 88.6% (+/-SE 4.8%) and 92.1% (+/-SE 4.4%), respectively. Six graft stenoses were detected in duplex surveillance. There were no infections related to polyester mesh. External scaffolding of infrainguinal vein grafts may be a promising innovation. Early results from this multicentre study show that polyester mesh is safe and feasible adjunct to peripheral revascularization enabling the use of otherwise non-optimal vein grafts with acceptable short-term patency.

Between carbonatite and lamproite—Diamondiferous Torngat ultramafic lamprophyres formed by carbonate-fluxed melting of cratonic MARID-type metasomes

New U–Pb perovskite ages reveal that diamondiferous ultramafic lamprophyre magmas erupted through the Archean crust of northern Labrador and Quebec (eastern Canada) between ca. 610 and 565 Ma, a period of strong rifting activity throughout contiguous Laurentia and Baltica. The observed Torngat carbonate-rich aillikite/carbonatite and carbonate-poor mela-aillikite dyke varieties show a large spread in Sr–Nd–Hf–Pb isotope ratios with pronounced correlations between isotope systems. An isotopically depleted component is identified solely within aillikites ( 87Sr/ 86Sr i = 0.70323–0.70377; εNd i = +1.2–+1.8; εHf i = +1.4–+3.5; 206Pb/ 204Pb i = 18.2–18.5), whereas some aillikites and all mela-aillikites range to more enriched isotope signatures ( 87Sr/ 86Sr i = 0.70388–0.70523; εNd i = −0.5 to −3.9; εHf i = −0.6 to −6.0; 206Pb/ 204Pb i = 17.8–18.2). These contrasting isotopic characteristics of aillikites/carbonatites and mela-aillikites, along with subtle differences in their modal carbonate, SiO 2, Al 2O 3, Na 2O, Cs–Rb, and Zr–Hf contents, are consistent with two distinctive metasomatic assemblages of different age in the mantle magma source region. Integration of petrologic, geochemical, and isotopic information leads us to propose that the isotopically enriched component originated from a reduced phlogopite-richterite-Ti-oxide dominated source assemblage that is reminiscent of MARID suite xenoliths. In contrast, the isotopically depleted component was derived from a more oxidized phlogopite-carbonate dominated source assemblage. We argue that low-degree CO 2-rich potassic silicate melts from the convective upper mantle were preferentially channelled into an older, pre-existing MARID-type vein network at the base of the North Atlantic craton lithosphere, where they froze to form new phlogopite-carbonate dominated veins. Continued stretching and thinning of the cratonic lithosphere during the Late Neoproterozoic remobilized the carbonate-rich vein material and induced volatile-fluxed fusion of the MARID-type veins and the cold peridotite substrate. Isotopic modelling suggests that only 5–12% trace element contribution from such geochemically extreme MARID-type material is required to produce the observed compositional shift from the isotopically most depleted aillikites/carbonatites towards enriched mela-aillikites. We conclude that cold cratonic mantle lithosphere can host several generations of contrasting vein assemblages, and that each may have formed during past tectonic and magmatic events under distinctively different physicochemical conditions. Although cratonic MARID-type and carbonate-bearing veins in peridotite can be the respective sources for lamproite and carbonatite magmas when present as the sole metasome, their concomitant fusion in a complex source region may give rise to a whole new variety of deep volatile-rich magmas and we suggest that orangeites (formerly Group 2 kimberlites), kamafugites, and certain types of ultramafic lamprophyre are formed in this manner.

Attempt to determine U-Th ages of calcite veins in the Nojima fault zone, Japan

Fluids within fault zones can change the physical and chemical properties of fault materials and have a substantial influence on faulting. Therefore it is important to understand the nature and timing of fluid migration through fault zones. In order to evaluate the timing of fluid infiltration into a deep fault zone on Awaji Island in southern Japan, we attempted to measure U-Th radioactive disequilibrium of carbonate minerals from the Nojima fault, which triggered the 1995 Kobe earthquake. Bulk carbonate samples of vein material have U concentrations of 1.2 to 2 ppm and Th concentrations of 1.6 to 6.5 ppm. The high Th abundances derived from detritus requires correction for initial 230Th in order to acquire an accurate U-Th age. Bulk carbonate samples plot near the equiline in a (230Th/232Th)-(234U/232Th) diagram, suggesting that they precipitated around or before 450 ka. Monte Carlo simulation with finite-age constraint in the IsoPlot program yields a 230Th/234U age of 486 (+380, -190) ka. The presence of radioactive disequilibrium in (234U/238U) indicates that the calcite precipitation age was younger than 1 Ma. The results of leaching experiments indicate that a leaching procedure after firing causes considerable laboratory fractionation of U and Th and does not provide usable age information.

Fluid Temperature and Salinity Characteristics of the Matagami Volcanogenic Massive Sulfide District, Quebec

Fluid inclusions hosted within various lithologic units of the >40 million metric ton (Mt) Matagami district, Abitibi greenstone belt, preserve samples of Archean volcanogenic massive sulfide (VMS) and postvolcanogenic massive sulfide hydrothermal fluid. Microthermometric measurements on ore-hosted primary two-phase liquid-vapor inclusions from Matagami’s south limb deposits indicate that the VMS hydrothermal fluid was highly saline (16.2 ± 4.7 wt % NaCl-CaCl2 equiv, 1σ, n = 230) and of moderate temperature (trapping temperature, Tt = 208° ± 32°C, 1σ, n = 230). A fluid with these characteristics is capable of transporting ~5 × 10−4 m (30 ppm) Zn as ZnCl3 − and ZnCl4 2− chloride complexes. However, the low temperature of this fluid precluded efficient Cu transport (≤ 3 ppm), which may in part explain the relatively Cu poor nature of the Matagami deposits. Calculated densities of this ore fluid as high as 1.10 g/cm3 are consistent with a bottom-hugging brine model. However, a subset of the data indicate a fluid less dense than ambient seawater, suggesting that buoyant hydrothermal plumes were also present. A microthermometrically determined high CaCl2 content (XNaCl <0.55, molar Na/Ca = 2.3/1) for the VMS ore-hosted primary fluid is consistent with an Archean hydrothermal fluid more Ca-rich than modern-day seawater. Quartz-epidote veins located in the hydrothermal cracking zone of the Bell River Complex host primary liquid-vapor-halite inclusions. These inclusions are interpreted to be samples of the deep-seated equivalent to the VMS ore-hosted hydrothermal fluid described above. Microthermometry indicates that these inclusions trapped a high-temperature brine (Tt = 373° ± 44°C, 1σ , n = 92; 38.2 ± 1.9 wt % NaCl equiv, 1σ , n = 92). We interpret this brine to be a phase-separated product of (modified) model seawater (3.2 wt % NaCl), an exsolved magmatic fluid, or a combination thereof, deep within the hydrothermal system at 650° to 670°C and a near-lithostatic pressure of 90 MPa. Phase separation and subsequent convection lowered the temperature of the brine prior to its entrapment within the hydrothermal cracking zone. The occurrence of high-temperature brine overlain by lower temperature/salinity fluid suggests a two-cell convection model, consistent with metal mass-balance calculations for the south limb. The high salinity of the ore-hosted fluid inclusions indicates two possibilities: (1) a significant amount of brine was incorporated into the upper cell and mixed with heated seawater during convection; (2) Archean seawater itself was very saline and of variable salinity. With the cooling of the Bell River Complex, lower temperature fluids, dominantly of seawater origin, circulated deep within the hydrothermal system. Modified by water-rock interaction, yet not phase separated, these fluids sealed off the remnant permeability of the fracture network of the hydrothermal cracking zone and were locally trapped as secondary liquid-vapor fluid inclusions (homogenization temperature, Th = 242° ± 17°C; 9.1 ± 1.6 wt % NaCl equiv, 1σ , n = 14) hosted within the Bell River Complex quartz-epidote vein material. Post- and/or waning-stage VMS hydrothermal activity is evident from the presence of quartz-epidote veins crosscutting Wabassee Group hanging-wall rocks. Microthermometry on quartz-hosted primary liquid-vapor fluid inclusions suggests that this activity occurred at relatively low temperatures (Th = 76°–177°C, n = 212), over a wide range of salinity (6.0–32.4 wt % NaCl-CaCl2 equiv, n = 212), and with a high apparent CaCl2 content (XNaCl <0.06). These fluid inclusion data illustrate the importance of subsea-floor chemical and physical processes directly related to metal transport and deposition in VMS systems. In particular, phase separation deep within the hydrothermal system is interpreted as a key process for generating saline brines capable of forming significant ore deposits.

Fault and vein relationships in a reverse fault system at the Centenary orebody (Darlot gold deposit), Western Australia: Implications for gold mineralisation

The Centenary orebody within the Darlot gold deposit is located in the Yandal greenstone belt in the Yilgarn Craton, Western Australia. At Centenary, moderately (∼45°) west dipping reverse faults and steeply dipping (>70°) faults of variable strike failed during gold mineralisation in response to sub-horizontal east-west shortening and sub-vertical extension. Gently dipping veins are temporally, genetically and spatially related subsidiary structures to west dipping reverse and steeply dipping faults. Line analyses of subsidiary vein distributions in 23 drill cores around Centenary suggest that the gold-related subsidiary veins are localised within a 200–300 m wide tabular linking damage zone between three west dipping faults (Thompson, Lords and Walters). The damage zone is a laterally stepping relay zone between the Thompson and Lords–Walters faults and has a pull-apart geometry. Anomalous vein-related extensional strain (>0.005), vein density (>0.20) and power-law vein thickness population characteristics ( D t 0.58–1.84) distinguish this zone from the surrounding rock. Within the linking damage zone the highest number and volume of veins are observed at the tip of the Walters fault. At the fault tip, the exponent of the power-law distribution of vein thickness is highest ( D t 1.84) indicating that vein-related extensional strain is distributed on a high number of relatively small thickness veins. At approximately 300 m distance from the fault tip the densities of veins and the measured exponents of power-law vein thickness distributions are lower (<0.80 and D t <1.3, respectively). However, bulk vertical extensional strain remains high (>0.005), indicating that subsidiary vein material is concentrated on a greater number of anomalously thick veins. These systematic variations suggest that the fault tip imparted a strong control on vein localisation. Strain localisation within the linking damage zone is complex with coefficients of variation of vein spacing greater than one implying vein clustering. Gently dipping veins occur as wing crack arrays to the reverse faults and also in arrays comprising curviplanar, intersecting networks of subsidiary veins. The linking damage zone corresponds closely with the Centenary gold resource indicating that it has been an important locus for the focussed flux of gold-bearing hydrothermal fluids. However, within the damage zone, individual veins and vein arrays on the tens of metre scale do not always correlate with high gold grade indicating additional complexity within the system.

Intraplate volcanism in New Zealand: the role of fossil plume material and variable lithospheric properties

The geologic evolution of the New Zealand microcontinent was characterised by intermittent Cretaceous to Quaternary episodes of intraplate volcanism. To evaluate the corresponding mantle evolution beneath New Zealand with a specific focus on the tectonic evolution, we performed a combined major and trace element and Hf, Nd, Pb, Sr isotope investigation on a suite of representative intraplate volcanic rocks from both main islands and the Chatham Islands. Isotopically, the data set covers a range between “HIMU-like” end member compositions (206Pb/204Pb: 20.57, 207Pb/204Pb: 15.77, 87Sr/86Sr: 0.7030, eHf: + 3.8, eNd: + 4.2), compositions tending towards MORB (206Pb/204Pb: 19.01, 207Pb/204Pb: 15.62, 87Sr/86Sr: 0.7028, eHf: + 9.9, eNd: + 7.0) and compositions reflecting the influence of subducted sediments (206Pb/204Pb: 18.99, 207Pb/204Pb: 15.67, 87Sr/86Sr: 0.7037, eHf: + 4.4, eNd: + 3.9). Whereas volcanism on the Chatham Islands constitutes the HIMU end member of our data set, intraplate volcanic rocks from the North Island are dominated by MORB-like compositions with relatively radiogenic 206Pb/204Pb signatures. Volcanic rocks from the South Island form a trend between the three end members. Assuming a polybaric melting column model, the primary melt compositions reflect variations in the degree of melting, coupled to variable average melting depths. As the three isotope and trace element end members occur throughout the volcanic episodes, the “HIMU-like” and the sediment influenced signatures most likely originate from a heterogeneous subcontinental lithospheric mantle, whereas an asthenospheric origin is inferred for the MORB-like component. For the South Island, affinities to HIMU wane with decreasing average melting depths whereas MORB and sediment-like signatures become more distinct. We therefore propose a polybaric melting model involving upper asthenospheric mantle and a lithospheric mantle source that has been modified by subduction components and veins of fossil “HIMU-like” asthenospheric melts. The proportion of asthenospheric versus lithospheric source components is controlled by variations in lithospheric thickness and heat flow, reflecting the different tectonic settings and rates of extension. Generally, low degree melts preferentially tap enriched vein material with HIMU signatures. The widespread occurrence of old Gondwana-derived lithospheric mantle beneath intraplate volcanic fields in East Gondwana is suggested by overall similarities between New Zealand intraplate volcanic rocks and volcanic rocks in East Australia and Antarctica. The petrogenetic model proposed here may therefore serve as a general model for the petrogenesis of Cretaceous to Recent intraplate volcanic rocks in former East Gondwana.

Origin of the secondary REE-minerals at the Paratoo copper deposit near Yunta, South Australia

AbstractThe Paratoo copper deposit, located in the Neoproterozoic to Cambrian Adelaide Geosyncline, South Australia, produced around 360 tons of Cu between 1888 and 1967 from oxidized ores. The deposit is located in the core of a breached, doubly plunging anticline, near a zone of disruption containing brecciated Adelaidean sedimentary rocks and dolerite (‘Paratoo Diapir’), and hosted in dolomitic shales of the Neoproterozoic Burra Formation. Near the surface, the mineralization resides mainly in deeply weathered quartz-magnetite-sulphide (pyrite, chalcopyrite) veins (⩽10 cm wide). At depth, drill cores reveal disseminated magnetite, pyrite, chalcopyrite, copper sulphide and native copper associated with extensive potassic alteration. K-Na-rich fluids also affected the dolerite in the ‘Paratoo diapir’, resulting in the precipitation of K-feldspar, dravite and K-bearing chabazite-Na. The most likely scenario for the genesis of the Paratoo deposit involves circulation of basinal fluids, focusing into the ‘Paratoo Diapir’, and ore precipitation through neutralization by fluid-rock interaction with the dolomitic shales hosting the mineralization.The Paratoo deposit is deeply weathered, with malachite and chrysocolla (± tenorite and cuprite) containing the bulk of the copper recovered from the shallow workings. A diverse assemblage of secondary REE-bearing carbonate minerals, including the new species decrespignyite-(Y) and paratooite-(La), is associated with the weathered base metal and magnetite ores. Whole-rock geochemical analyses of fresh and mineralized host rock and of vein material reveals that the mineralization is associated with a strong, albeit highly variable, enrichment in light rare earth elements (LREE). This association indicates that REE and base metals were introduced by the same hydrothermal fluid. The strong negative Ce anomaly found in secondary REE minerals and mineralized rock samples suggests an upgrade of the REE contents in the weathering zone, insoluble Ce4+ being left behind.The Fe-oxide-REE-base metal association at Paratoo is also characteristic of the giant Mesoproterozoic Fe oxide copper gold deposit of Olympic Dam, located 350 km to the NW. A similar association is found in the Palaeozoic deposits of the Mt Painter Inlier, 300 km to the NNE. The widespread occurrence of this elemental association in the Province probably reflects the geochemistry of the basement, which contains numerous Mesoproterozoic granites enriched in REE and U.

Remnants of boninitic melts in the upper mantle beneath the central Pannonian Basin?

We present a detailed textural and compositional study of two orthopyroxene-rich olivine websterites. One occurs as a vein in a harzburgite xenolith and the other is an individual xenolith, both found at Szentbekkalla in the Bakony–Balaton Highland Volcanic Field (central Pannonian Basin, western Hungary). The textural features of these orthopyroxene-rich rocks suggest that they crystallized from silicate melts to form veins in peridotite mantle rock. Their geochemical features, such as the presence of Al2O3-poor orthopyroxenes, Cr-rich spinels, and clinopyroxenes with U-shaped chondrite-normalized REE-patterns, indicate that the vein material formed from Mg-rich silicic (boninitic) melts at mantle depths. The olivine fabric investigation of both the veins and the wall-rock suggest that the development of the veins was followed by subsequent recrystallization during the Cenozoic evolution of the Carpathian–Pannonian region.

The development of bone-shaped structures in initially segmented layers during layer-parallel extension: numerical modelling and parameter sensitivity analysis

In orogenic zones the geometric occurrence of specific tectonic structures can often be related to contrasting rheological properties of rock materials. One of such tectonic structures is layer-perpendicular naturally fractured layers with vein infill that underwent subsequent deformation. Internal deformation by coaxial extension of these segmented layers, with host-rock material less competent than the vein material, gives rise to the development of bone-shaped structures (i.e. dogbones). In this paper, the formation of such dogbones is modelled using finite element techniques. A parameter sensitivity analysis of the model demonstrates that the degree of extension of the host-rock segments, their initial aspect ratio and the competence contrast between vein material and host-rock are the controlling parameters for the final shape of the dogbones during coaxial extension. The results, moreover, suggest that the specific geometry of the dogbones can serve to quantify competence contrasts between the host-rock and vein material during flow at geological strain rates.

Alkali-feldspathic material entrained in Fe,S-rich veins in a monomict ureilite

The Elephant Moraine (EET) 96001 ureilite contains a remarkable diversity of feldspars, which occur as tiny (no more than 60 ?m maximum dimension) grains within a few Fe,S-rich (now weathered to mostly Fe oxide) veins. Molar S:Fe ratio in the veins averages 0.08 0.02. The veins meander and feature large fluctuations in apparent width; they appear to have entered this monomict breccia by a gentle, percolative process, not by violent impact injection. The feldspars are accompanied by a diverse suite of K-rich (and generally also Ti-rich) feldspathic glasses, and also major proportions of silica and pyroxene, which is largely fassaitic. A rhnite-like phase is also found, and, as inclusions in one of the fassaites, a Cr-poor spinel-like phase. The feldspars mostly feature remarkably high K/Na compared to feldspars of comparable An from polymict ureilites. The EET 96001 feldspathic component was probably once part of a thin basaltic crust on a ureilite asteroid. The spinel included in one of the fassaites formed at remarkably high fO2 (apparent oxidation state of iron: 41 atom% Fe3+), suggesting that the parent magma possibly assimilated near-surface water (however, the Fe3+was not directly measured, and has conceivably been affected by terrestrial weathering; also, there is no assurance that this fassaite originated together with the typical feldspar). We speculate that the feldspathic component was mixed into the dense, Fe,S-rich vein material, and very soon thereafter the Fe,S-rich vein material was emplaced adjacent to the EET 96001 host ureilite, at an advanced stage in a chaotic catastrophic disruption and partial reassembly process that affected all ureilites. The high-K nature of the EET 96001 feldspathic component, including the feldspathic glasses, suggests that fractional fusion may not have been as common during ureilite anatexis as has been inferred from recent studies of clast assemblages in polymict ureilites.

Quality Monitoring of Thermally Degraded Stationary Gas Turbine Blade Material by Surface Wave Technique

For the quality monitoring and reliable application of stationary gas turbine blade (vane), near surface damages in the isothermally degraded vein material (i.e., cobalt based superalloy) were characterized by ultrasonic surface wave technique. Surface wave velocity and attenuation were measured for the artificially degraded specimens at 1100°C, together with microstructural analysis and micro-hardness measurement. Surface wave velocity increased with thermal degradation time, which was attributed to the increasing depletion of solute chromium near the surface. Strong frequency dependence of surface wave velocity was observed in the specimens with surface depletion layer. Attenuation coefficient of surface wave increased with increasing degradation time. The potential of ultrasonic surface wave technique to assess near surface damages in vein material was discussed with an emphasis on the relationship between the microstructural damage and the governing principles of ultrasonic response.

Sources of primitive alkaline volcanic rocks from the Central European Volcanic Province (Rhön, Germany) inferred from Hf, Os and Pb isotopes

Basanites and nephelinites from the Tertiary Rhon area (Germany), which are part of the Central European Volcanic Province (CEVP), have high MgO, Ni and Cr contents and prominent garnet signatures indicating that they represent near-primary magmas formed by melting of a CO2-bearing peridotitic mantle source at high pressure. The Pb and Hf isotope (and previously published Nd and Sr isotope) ratios of the Rhon lavas are rather uniform, whereas the Os isotope composition is highly variable. For the most primitive basanites, Pb, Os and Hf isotope compositions fall within the range of enriched MORB and some OIB. Other basanites and nephelinites with low Os concentrations have distinctly more radiogenic Os (187Os/188Os: 0.160–0.469) isotope compositions, which are inferred to originate from crustal contamination. The samples with the highest Os concentrations have the lowest Os isotope ratios (187Os/188Os(23 Ma): 0.132–0.135), and likely remain unaffected by crustal contamination. Together with their fairly depleted Sr, Nd and Hf isotope ratios, the isotopic composition of the Rhon lavas suggests derivation from an asthenospheric mantle source. Prominent negative K and Rb anomalies, however, argue for melting amphibole or phlogopite-bearing sources, which can only be stable in the cold lithosphere. We therefore propose that asthenospheric melts precipitated at the asthenosphere-lithosphere thermal boundary as veins in the lithospheric mantle and were remelted or incorporated after only short storage times (about 10–100 million years) by ascending asthenospheric melts. Due to the short residence time incorporation of the vein material imposes the prominent phlogopite/amphibole signature of the Rhon alkaline basalts but does not lead to a shift in the isotopic signatures. Melting of the lithospheric mantle cannot strictly be excluded, but has to be subordinate due to the lack of the respective isotope signatures, in good agreement with the fairly thin lithosphere observed in the Rhon area. The fairly radiogenic Pb isotope signatures are expected to originate from melting of enriched, low melting temperature portions incorporated in the depleted upper (asthenospheric) mantle and therefore do not require upwelling of deep-seated mantle sources for the Rhon or many other continental alkaline lavas with similar Pb isotope signatures.

The mercury and silver contents of gold in quartz vein deposits, Otago Schist, New Zealand

A regional study of gold from Otago Schist vein deposits from both Caples and Torlesse Terranes has revealed the presence of both Au‐Ag and Au‐Ag‐Hg alloys in both terranes. Almost all Hg‐bearing gold occurs in east Otago vein systems, and Hg‐free gold occurs in central and northwest Otago vein systems, irrespective of host terrane. One Central Otago mineralised zone has up to 1.7 wt% Hg in the gold. Au‐Ag alloy (3–8 wt% Ag) is typical for gold found in most Torlesse‐hosted vein deposits, and Au‐Ag‐Hg alloys with 1–4 wt% Hg are found in vein material from the Torlesse‐hosted Hyde‐Macraes Shear Zone. Au‐Ag‐Hg alloy (3–8 wt% Ag, 2–8 wt% Hg) is found in many Caples‐hosted vein deposits. There is no relationship between depth of vein emplacement and Hg content of gold, as both high and low Hg gold are found in shallow‐formed (<2 km) and deep‐formed (>6 km) deposits. There is no spatial relationship between Hg‐bearing gold and cinnabar‐bearing veins that occur in Caples Terrane rocks on the southern edge of the schist belt. Mercury‐bearing placer gold in eastern Southland may have been derived from erosion of east Otago veins. The source of Hg‐bearing placer gold in northern Southland is unknown as yet.

Early Transposition of the Sartorius Muscle for Exposed Patent Infrainguinal Bypass Grafts

The traditional approach for patent and exposed and infected infrainguinal bypass grafts in the groin has included wide operative debridement and secondary or delayed primary closure. However, this has been associated with significant risk of further contamination and length of stay. The authors reviewed their experience using the wide debridement, sartorius muscle flap transposition, and primary wound closure as an alternative. During the past 5 years, they have had 50 patients with major wound necrosis or infection in the groin or thigh with the graft or native artery being exposed after debridement. This group included 28 men; 74% of the patients had hypertension, 58% had diabetes, and 20% had renal failure. The grafts were split evenly between native vein and prosthetic material. After wide debridement, closure was performed by the vascular surgeon using the sartorius muscle flap. Postoperatively, there was an 8% major amputation rate and a 12% mortality rate in the first 30 days. One patient developed a pseudoaneurysm 5 weeks after placement of the flap. This patient underwent removal of the infected polytetrafluoroethylene graft with ligation of the common femoral artery. None of the procedures have resulted in further systemic or graft sepsis. None have resulted in arterial or graft blowout. Follow-up was for an average of 18 months. Closure of groin and thigh wounds with exposed bypass graft or native artery can be safely performed with the sartorius muscle flap with excellent results. The length of stay of these patients compared to historical controls is acceptable. Furthermore, the chance of infection of the native artery or bypass may be reduced. Familiarity with this simple technique can be a valuable tool for the vascular surgeon.

Bacillus cereus, gold and associated elements in soil and other regolith samples from Tomakin Park Gold Mine in southeastern New South Wales, Australia

Efficient exploration for new Au deposits is increasingly important as existing deposits become depleted. This is particularly relevant in Australia, where exploration can be difficult because of a thick regolith cover. New and effective methods of exploration need to be developed, and possibilities lie in geomicrobiological methods. For instance, Bacillus cereus, a common soil bacterium, has been shown to act as a biogeochemical indicator for concealed mineralisations, including vein-type Au deposits. We report the results of the first Australian case study of the association of B. cereus and Au at the Tomakin Park Gold Mine in southeastern New South Wales. Soil samples from the Ah horizon were analysed for B. cereus spores and 56 major and trace elements. The results show enrichment of Au, As, B. cereus spores and, to a lesser extent, Sb, Bi and Pb over the top of the Au deposit. Gold concentrations over the mineralisation range from 100 ppb to 1.1 ppm compared to a background of 2 ppb and As concentrations are enriched to 100 ppm from a background of 5 ppm. B. cereus spore counts were up to 10 times higher in soils with elevated concentrations of Au. Factor analysis indicates four main associations: TiO 2+lanthanides+actinides; CaO+MgO+Cs+Be+Ba(+Ga+Pb+Rb); B. cereus+Au+As+Sb+Bi(+Pb); Fe 2O 3+MnO+Co+Ni+Cu+Mo. Selective sequential leaching was used to study the fractionation of Au and As in soils, other regolith materials and Au-bearing vein quartz to infer their mobility and bioavailability. In unweathered quartz vein material, the majority of the Au was extracted only in the strongest, final step, with aqua regia. However, in soils from the Ah horizon, 50% of the Au was present in the water-, ammonium acetate- and sodium pyrophosphate- and hydroxylamine hydrochloride-extractable fractions. In contrast, As displays little change in fractionation with an increasing degree of weathering, and is predominantly associated with the operationally defined Mn- and Fe-oxides and oxyhydroxides. These results indicate that: (i) Au is mobilised during the weathering of the host rock; (ii) Au is bioavailable in these soils; and (iii) the increase in B. cereus spores is likely to be linked to elevated concentrations of bioavailable Au in these soils. The results indicate also that an effective biogeochemical exploration technique may be developed, where B. cereus spore counts are measured in the field and used as a pre-screening method to target areas useful for further sampling and complete geochemical analysis.