Vein Sets Research Articles

Superficial Veins in the Cubital Fossa Regions among the Nepalese and Indian Medical Students of a Medical College in Nepal: A Descriptive Cross-Sectional Study

Background The veins in the upper limb are classified as superficial or deep, with deep veins, such as the venae comitantes and axillary vein, coming after the major arteries. The subcutaneous tissue contains the superficial veins, which link to the deep veins. These veins include the basilic, cephalic, median cubital, and median antebrachial veins. These superficial veins are clinically significant for phlebotomy, transfusion, and cardiac catheterization, and it joins the median cubital vein at the elbow. It is essential to comprehend the structure and patterns of cubital superficial veins in order to design dialysis access and minimise hazards. Materials and Methods Studying the superficial venous organisation in the cubital fossa of 192 MBBS preclinical sciences students, ages 18 to 24, was a cross-sectional observational study carried out at the Nobel Medical College Teaching Hospital in Nepal. A tourniquet and skin marker/tailor's chalk were used in the study to examine 384 anterior aspects of the arms. Six sets of veins were distinguished from the skin's veins. Tiny veins, cubital wounds, or thick tissue layers disqualified students. Results A study of 192 preclinical sciences students at Nobel Medical College Teaching Hospital in Biratnagar found that type II variant was the most common venous pattern in the cubital fossa region, followed by type I in 24.75%, and the lowest being the type VI pattern in 3.35%. Conclusion It was discovered that the patterns of superficial veins at the cubital fossa did not significantly alter based on the gender or nationality of the individual. Overall, the most common venous pattern was type II, though type I was more frequently seen in female subjects but the difference was statistically insignificant.

The Geometry, Spatial Distribution and Texture of Slate‐Hosted Calcite Veins in the Helvetic Flysch Units—Insights in Structural and Fluid Processes Within a Paleo‐Accretionary Complex

AbstractThe exhumed Infrahelvetic Flysch Units in the eastern central Alps in Switzerland are a field analog to modern accretionary wedges at active plate boundaries. In these seismically active convergent settings, water‐saturated sediments undergo consolidation, and diagenetic to low‐grade metamorphic processes cause complex fluid‐rock interactions. To contribute to the understanding of structural and fluid processes and their interaction with seismic activity, we present quantitative information on the geometrical and spatial distribution of slate‐hosted calcite veins from the Infrahelvetic Flysch Units that show mutual overprinting relationships with the ductile phyllosilicate‐rich matrix. Two vein systems that form in the deeper part of the inner wedge are characterized: (a) layer‐parallel veins (meter‐scale) forming spatially repetitive vein‐arrays and (b) pervasively distributed, steep micron‐veinlets, that cross‐cut the thicker layer‐parallel veins and the ductile matrix. Synchrotron X‐ray Fluorescence Microscopy (XFM) is instrumental in detecting previously unseen densely spaced micron‐veinlets. The spatial distribution of micron‐veinlets indicates pervasive layer‐perpendicular fluid transport in response to dissolution‐precipitation creep through the wedge. Layer‐parallel veins form vein‐arrays with thicknesses on the meter‐scale suggesting that fluids are progressively localized in channels up‐scale. Both vein sets form in an alternating fashion with two different enhanced flux directions, which could be indicative for a critically stressed wedge with near‐lithostatic fluid pressures. The layer‐parallel veins and vein‐arrays could represent seismic events with low magnitude earthquakes (Mw up to 4.0) or slow‐slip events currently found at active plate boundaries, while micron‐veinlets and dissolution‐precipitation processes accommodate slow interseismic deformation.

Superposed fracture networks

AbstractThe concept of superposed fracture networks consisting of different generations, and often types, of fractures that have developed sequentially is discussed. Superposed networks can consist of different types of extension or shear fractures, and each fracture may abut, cross or follow (reactivate) earlier fractures. An example of a superposed fracture network in Liassic limestones in Somerset, UK, is presented, which comprises two sets of veins and a later joint network. The veins develop as damage zones around faults, with veins of the later set crossing or trailing along the earlier set. The later joints either cross-cut the earlier veins or reactivate them, the latter being common for the thicker (more than about 5 mm) veins. The veins and joint networks have markedly different geometries and topologies. The veins are spatially clustered and are typically dominated by I-nodes, while the joints are more evenly distributed and tend to be dominated by Y-nodes. The combined network of veins and joints at Lilstock is dominated by X-nodes because so many joints cross-cut the earlier veins. Understanding the development of superposed fracture networks leads to better understanding of the kinematic, mechanical, tectonic and fluid flow history of rocks.

Application of checklist-based nursing in management of pediatric intravenous infusion via scalp vein set

Application of checklist-based nursing in management of pediatric intravenous infusion via scalp vein set

Nb-Ta-Ti oxidy v topazových granitech cíno-wolframového rudního ložiska Ehrenfriedersdorf (Krušné hory, Německo)

Nb-Ta-Ti-bearing oxide minerals represent the most common hosts of Nb and Ta in high-F, high-P2O5, Li-mica granites from the Sauberg granite stock in the Krušné hory/Erzgebirge Mts. batholith (Figure 1). The stock hosts the Ehrenfriedersdorf ore deposit, representing the most significant Sn-W ore deposit in this area. This ore deposit was mined from the 13th century until the year 1990. Since July 2019, the Ehrenfriedersdorf mining landscape makes a significant part of the UNESCO world heritage site, the Montanregion ore mountains. Fine- to medium-grained granites of the Sauberg granite stock are composed by quartz, albite (An 0.1–0.5), K-feldspar (Or97–99, Ab1–3), Li-mica and topaz. Both feldspars are partly enriched in phosphorus (up to 0.52 wt. % P2O5). Apatite, zircon and monazite are accessory phases. The Nb-Ta-Ti-bearing oxide minerals – Nb-Ta-rich rutile, Fe-columbite, W-ixiolite occur in accessory amounts in ore-bearing structures together with cassiterite and wolframite. The main ore-bearing structures are represented by mineralised vein structures and metasomatic stringer zones, which are the most significant. The latter are characterised by numerous parallel to sub-parallel E-W striking en-echelon sets of ore veins. The Sauberg granite stock hosting the Nb-Ta mineralization is mostly formed by highly fractionated, highly peraluminous S-type granites (ASI = 1.2–1.4) with Nb/Ta ratio = 1.8–5.5 and depletion in CaO, MgO, Ba, Sr and high-field-strength elements. (Table 1, 2). The Nb-Ta-bearing rutile is the most common Nb and Ta carrier and occurs mostly as subhedral inclusions in Li-mica flakes. It has very low Mn/(Mn Fe) ratio (0.0–0.01) and low Ta/(Ta Nb) ratio (0.04–0.25) (Table 3). Columbite-group minerals are represented by columbite-(Fe) with a Mn/(Mn Fe) ratio varying from 0.11 to 0.14 and with relatively low Ta/(Ta Nb) values (0.08–0.26) (Table 4). The rare, W-ixiolite was observed as needle-like subhedral crystals and/or as inclusions in needle-like aggregates of wolframite. The W-ixiolite is Fe-rich with relatively low Mn/(Mn Fe) and Ta/(Ta Nb) values of 0.11–0.13 and 0.07–0.25, respectively (Table 5).

Precise U-Pb dating of incremental calcite slickenfiber growth: Evidence for far-field Eocene fold reactivation in Ireland

Abstract The Variscan orogen in southern Ireland and Britain is characterized by an intensely deformed, E-W–trending fold-and-thrust belt. Farther north in Ireland, the Carboniferous North Dublin Basin exhibits tight chevron folds and kinematically linked en echelon vein sets, along with bedding-parallel veins with slickenfibers. This deformation is assumed to be Variscan in age, despite lying 150 km north of the supposed Variscan “front.” The laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U-Pb dating of these calcite veins undertaken for this study showed that relict Variscan U-Pb ages are very poorly preserved. Instead, late Eocene ages were obtained from many calcite veins, including fold hinge breccias and bedding-parallel slickenfiber veins associated with N-S shortening (flexural slip). Also, U-Pb ages from one bedding-parallel vein showed protracted flexural slip over ~5 m.y. during late Eocene times. Detection of the growth domains within this vein was facilitated by the imaging approach to LA-ICP-MS U-Pb dating adopted in this study, which can identify age-homogeneous domains by integrating spatial U-Pb isotopic information with maps of petrogenetically diagnostic major and trace elements. The late Eocene fold reactivation phase was hitherto undetected on the Irish mainland, but regional Cenozoic N-directed shortening has been documented in Mesozoic–Cenozoic sequences of the southern Irish Sea, Celtic Sea, southern England, and the Paris Basin. We attribute late Eocene fold reactivation to far-field, N-directed shortening associated with the Alpine/Pyrenean orogenies. It is likely that many Variscan or Caledonian folds, particularly in southern onshore Ireland, were reactivated during Eocene–Oligocene shortening, which has not been recognized to date because of the lack of post-Variscan markers (e.g., dikes, Mesozoic–Cenozoic cover sequences).

Shattered Veins Elucidate Brittle Creep Processes in the Deep Slow Slip and Tremor Region

AbstractDeep Slow Slip and Tremors (SSTs) are a combination of transient clusters of tectonic tremors and slow slip associated with extremely elevated fluid pressures. SSTs are thought to reflect a transition from viscous to brittle plate interface rheology and likely exert a first‐order control on megathrust seismicity. Nevertheless, the deformation mechanisms governing the source of SSTs remain elusive. We herein document the occurrence of vein networks precipitated and brecciated within the deep SST region under blueschist‐facies conditions. These lawsonite‐rich vein sets exhibit extensive evidence of brittle deformation and are spatially related to localized, finely milled (cataclastic) shear bands. Petro‐geochemical data reveal that brittle deformation was accompanied by the injection of several ultramafic‐, mafic‐ and metasedimentary‐derived fluid pulses, imprinting characteristic Cr, high field strength elements, and light over heavy rare earth elements positive anomalies in the vein breccias while leaching light rare earth elements from the cataclastic blueschist host. Our results suggest that metamorphic veins represent zones of mechanical anisotropy within the rock volume prone to localized shearing, brittle deformation and episodic injection of externally derived fluids. These networks demonstrate the importance of former vein sets as structural heterogeneities in triggering fluid‐controlled brittle creep events. The combined effects of high pore fluid pressures and rheological heterogeneities in the form of metamorphic veins could trigger the nucleation and propagation of SSTs at the margins of this mechanically anisotropic environment, and thus determine where slip will take place along deep subduction interfaces.

Geology of Winu-Ngapakarra, Great Sandy Desert of Western Australia, a Recently Discovered Intrusion-Related Cu-Au Deposit

Abstract The Winu-Ngapakarra Cu-Au deposit (Winu) was discovered in late 2017. Winu is hosted in metamorphosed massive sandstones, siltstones, and lesser mafic rocks that are possible distal and deep-water correlatives of the Malu Formation of the Yeneena basin, also host to the large Telfer Au-Cu deposit. Structure at Winu is dominated by an inclined dome formed through interference between NNW- and WNW-trending folds. Copper-gold mineralization occurs in en echelon left-stepping lodes with strike lengths between 350 and 750 m and vertical depths exceeding 750 m, northerly trends, and moderate easterly dips. These higher-grade lodes are surrounded by an extensive halo of low-grade mineralization. Two gold-rich lodes in the southeast part of the Winu deposit strike roughly easterly, toward a gold-rich satellite deposit (Ngapakarra) approximately 2 km east of Winu. Mineralization at Winu is hosted by numerous thin, brittle veins and breccias. At least four distinct vein sets associated with Cu-Au mineralization are recognized: V1—early, weakly mineralized K-feldspar-white mica stockworks; V2—transitional magmatic-hydrothermal K-feldspar–rich veins; V3—quartz-sulfide–rich veins, breccias, and fractures and quartz-bismuth-gold veins with similar timing; and V4—poorly mineralized quartz veins. Barren carbonate-, chlorite-, white mica-, and pyrite-rich fractures (V5), breccias, and faults as well as thin dolerite dikes cut mineralization at Winu. Re-Os dating of molybdenite intergrown with chalcopyrite yielded ages of 658 to 655 Ma for the mineralized veins at Winu, and Ar-Ar dating of biotite yielded 619 Ma for an unmineralized post-ore quartz-biotite vein. A well-developed supergene chalcocite blanket overlies the primary mineralization. Element associations and vein and alteration textures and mineralogy classify Winu as an intrusion-related Cu-Au deposit of Neoproterozoic age. Although it shares features with the reduced porphyry copper-gold group, other features, such as the dominance of pyrite over pyrrhotite and the presence of trace amounts of sulfate minerals in the mineralization, are more in accordance with oxidized, intrusion-related systems. Mineralization at Winu was most likely triggered by rapidly changing stress fields during the Paterson orogeny and cooling of multiple fluid pulses above an intruding granite pluton that progressively decreased in temperature over time. Winu is unique in this region in that it preserves evidence for an early, reduced intrusion-related gold system overprinted by a more oxidized intrusion-related copper system.

MINERAL ASSEMBLAGES, FLUID INCLUSIONS, PYRITE TRACE ELEMENTS, AND S-O ISOTOPES OF GOLD ORES FROM THE CENOZOIC DAPING DEPOSIT, SW CHINA: IMPLICATIONS FOR THE GENESIS OF COMPLEX OROGENIC LODE GOLD SYSTEMS

Abstract The Cenozoic Daping orogenic gold deposit, on the southeastern margin of the Tibetan Plateau, China, contains four lode types that contain a total of 55 t gold. Pyrite-chalcopyrite–dominated (VA) and galena-dominated polymetallic sulfide veins (VB) hosted by Neoproterozoic diorite are associated with quartz-sericite-chlorite ± epidote (± barite in VB veins) alteration. Pyrite-dominated (VC) and pyrite-pyrrhotite–dominated veins (VD) hosted by Silurian dolostone (intercalated with carbon-bearing argillaceous limestone in VD veins) are related to ankerite-siderite-quartz ± sericite alteration. All have free gold spatially and temporally associated with pyrite, chalcopyrite, galena, pyrrhotite, or quartz. Most VA and VB veins are controlled by steeply SW-dipping ductile-brittle shear zones with jigsaw wall-rock breccias in VB veins, whereas gently SW-dipping faults host VC and VD veins. There are some significant differences between different veins: (1) there were more acidic mineralization conditions for VA and VB veins relative to VC and VD veins, and more oxidized conditions for VB veins relative to other veins; (2) pyrite is rich in Co-Ni in VA and VB veins, compared to enrichment in As-Au for VC and VD veins; (3) sulfide δ34S values of 3.2 to 11.8‰ (median 8.2‰) for VA, VC, and VD veins contrast with –4.6 to +0.9‰ (median 0‰) for VB veins. The contrasting mineral parageneses, pH values, and pyrite geochemistry can be attributed to fluid-rock interaction as evidenced by replacements of amphibole by sericite in diorite and dolomite by ankerite and siderite in dolostone. The lower (~8‰) VB sulfide δ34S values and interpreted fluid oxidation relative to other veins, together with the presence of breccias and barite, can be explained by phase separation due to flash vaporization triggered by extreme hydrofracturing. The consistent NW-trending vein sets, similar median S-O isotope ratios of original ore fluids, and lack of multistage overlap of gold mineralization and alteration zones support a single-source fluid for gold mineralization at Daping. This study is diagnostic rather than just indicative in that it systematically and quantitatively portrays the mineralization diversity in an orogenic gold system formed by a single-source fluid regulated by the external fluid-rock interactions and internal hydrofracturing.

Scalp vein set for venous cannulation in transfusion dependent thalassaemia major – A safe and effective long-term measure

Scalp vein set for venous cannulation in transfusion dependent thalassaemia major – A safe and effective long-term measure

Regional Intravenous Anaesthesia (Bier's block) in Black-headed Vulture (Coragyps atratus) Submitted to Digit Amputation

Background: The Coragyps atratus flies long distances in search of food and has a marked behaviour of food competition. Since they are frequently found in areas of recent human occupation, they are subject to trauma, which may require surgical interventions. Locoregional blocks are used as part of a balanced-anaesthesia protocol and are currently being evaluated in birds, with brachial plexus block being the main technique described in the literature. However, to our knowledge, this is the first description of intravenous regional anaesthesia (Bier's block) in a vulture. Thus, we aim to report the use of Bier's block with 1% lidocaine, in a black-headed vulture submitted to digit amputation. Case: A black-headed vulture (Coragyps atratus), weighing 2 kg, was rescued and referred to the Veterinary Hospital due to its inability to fly. Physical examination revealed a swollen digit in the right pelvic limb. Radiographic examination confirmed the intermediate phalanx fracture of the 4th digit of the right pelvic limb with signs suggestive of advanced osteomyelitis. The animal was referred to surgery for amputation of the affected digit. Before surgery, water and food were withdrawn for 12 h. Pre-anaesthetic medication consisted of 1 mg/kg midazolam and 0.5 mg/kg morphine intramuscularly (IM). Anaesthetic induction was performed through face mask with isoflurane, followed by orotracheal intubation with a 3 mm-endotracheal tube. Anaesthesia was maintained with isoflurane through a non-rebreathing circuit in 100% oxygen. Using a multiparametric monitor, heart rate (HR), respiratory rate (RR), end-tidal CO2 (EtCO2), oxyhemoglobin saturation (SpO2), electrocardiography (ECG), systolic blood pressure (SBP) and core temperature (CT) were evaluated. Antisepsis of the right pelvic limb was performed and an elastic band was applied around the distal region of the affected tibia to serve as a tourniquet. A scalp vein set was used to access the lateral saphenous vein in the region distal to the tourniquet, and 5 mg/kg lidocaine 1% was injected intravenously. The patient remained stable during the procedure, with no need for analgesic rescue. The tourniquet was gradually released 40 min past its application, being completely removed after 45 min of surgery. The anaesthetic supply was interrupted, with extubation after 4 min; the patient had satisfactory anaesthetic recovery. Discussion: The present report describes the success in using the technique of intravenous regional anaesthesia with 1% lidocaine for digit amputation performed on a specimen of black-headed vulture. The pre-anaesthetic medication provided analgesia, satisfactory sedation for venoclysis, and anaesthetic induction without complications. Anaesthetic induction and maintenance in birds are preferably performed with inhaled anaesthetics, thus the choice of mask induction. Despite the reduction in RR soon after induction, the patient remained on spontaneous ventilation. Bier's block using 5 mg/kg lidocaine showed to be an easy and safe technique in vultures, but doses up to 6 mg/kg lidocaine are not associated with adverse effects in birds. The intravenous regional anaesthesia technique described in this manuscript promoted adequate analgesia for the digit amputation procedure in black-headed vultures and allowed hemodynamic stability without significant anaesthetic complications. Thus, the present report points to the potential use of this locoregional block in other birds. Keywords: locorregional block, lidocaine, anaesthesia. Título: Anestesia regional intravenosa (bloqueio bier) em urubu-de-cabeça-preta (Coragyps atratus) submetido à amputação de dígito. Descritores: bloqueio locorregional, lidocaína, anestesia.

Genesis of the Island Gold Deposit, Ontario, Canada: Implications for Gold Mineralization in the Wawa Subprovince of the Superior Province

Abstract The Island Gold deposit represents an uncommon example of known economic mineralization in the Wawa subprovince, which has been tectonically correlated with the neighboring Abitibi subprovince that hosts worldclass orogenic gold deposits. The Island Gold deposit is hosted in dacite, gabbro, and tonalite-trondhjemite, and accompanied D2 deformation. The main ore zone dips steeply toward the south and consists of early shear-hosted laminated quartz veins and late extensional veinlets; both vein sets host gold mineralization. A set of shallowly dipping extensional quartz veins in the Goudreau zone located north of the main ore zones also host economic gold mineralization. Multiple sulfur isotope analysis of pyrite associated with gold-bearing alteration envelopes in the main ore zone indicates no involvement of sulfur affected by mass-independent fractionation, which rules out sulfur (± gold) sourced from nearby banded iron formation or metasedimentary material. However, a single analysis of pyrite from an auriferous Goudreau zone vein indicates the involvement of sulfur that underwent mass-independent fractionation, which suggests a different fluid source. Zircon U-Pb geochronology of pre- and postmineralization rock samples at Island Gold restricts the timing of mineralization to between ca. 2724 and 2672 Ma. Including previous results of detrital zircon geochronology, gold mineralization occurred between ca. 2680 and 2672 Ma. This age range is similar to the timing of gold mineralization at the Hemlo deposit in the Wawa subprovince but is slightly older than the bulk of orogenic gold mineralization in the neighboring southern part of the Abitibi subprovince. Multiple sulfur isotopes indicate that gold mineralization at Island Gold results from fluids of igneous affinity associated with second-generation transpressional deformation. The ore-controlling structures were developed in bends in regional shear zones focused around relatively competent premineralization plutons.

Progressive veining during peridotite carbonation: insights from listvenites in Hole BT1B, Samail ophiolite (Oman)

Abstract. The reaction of serpentinized peridotite with CO2-bearing fluids to form listvenite (quartz–carbonate rock) requires massive fluid flux and significant permeability despite an increase in solid volume. Listvenite and serpentinite samples from Hole BT1B of the Oman Drilling Project help to understand mechanisms and feedbacks during vein formation in this process. Samples analyzed in this study contain abundant magnesite veins in closely spaced, parallel sets and younger quartz-rich veins. Cross-cutting relationships suggest that antitaxial, zoned magnesite veins with elongated grains growing from a median zone towards the wall rock are among the earliest structures to form during carbonation of serpentinite. Their bisymmetric chemical zoning of variable Ca and Fe contents, a systematic distribution of SiO2 and Fe-oxide inclusions in these zones, and cross-cutting relations with Fe oxides and Cr spinel indicate that they record progress of reaction fronts during replacement of serpentine by carbonate in addition to dilatant vein growth. Euhedral terminations and growth textures of magnesite vein fill, together with local dolomite precipitation and voids along the vein–wall rock interface, suggest that these veins acted as preferred fluid pathways allowing infiltration of CO2-rich fluids necessary for carbonation to progress. Fracturing and fluid flow were probably further enabled by external tectonic stress, as indicated by closely spaced sets of subparallel carbonate veins. Despite widespread subsequent quartz mineralization in the rock matrix and veins, which most likely caused a reduction in the permeability network, carbonation proceeded to completion within listvenite horizons.

Structural Controls on Mineralization within the Huanggou Gold Deposit in the Southern Mesozoic Xuefengshan Orogen, South China

The Mesozoic Xuefengshan Orogen (XFSO) in South China hosts abundant gold ore deposits. The XFSO records a history of polyphase tectonic deformation and the structural controls on gold mineralization are poorly understood. The recently discovered quartz-vein type Huanggou gold deposit in the southern XFSO is characterized by multiple stages of deformation and represents an excellent natural laboratory for deciphering structural controls on gold mineralization in a complex orogenic belt. A systematic structural analysis indicates that the geometry of the Huanggou gold deposit and adjacent areas mainly resulted from four stages of deformation: (1) D1 top-to-the-NW sense of shearing; (2) D2 SE-directed back-folding and back-thrusting; (3) D3 NW–SE upright folding; and (4) D4 NW–SE normal faulting and fracturing. Two sets of quartz veins are exposed in the deposit: (1) SE-dipping Au-bearing quartz veins; and (2) NW-dipping non-mineralized quartz veins. The SE-dipping Au-bearing quartz veins were likely formed by the main deformation phase of the XFSO. During D1 top-to-the-NW simple shearing, these synkinematic Au-bearing quartz veins progressively evolved into sigmoidal shapes and rotated to a preferred SE-dipping orientation. Subsequently, D2 SE-directed back-folding and back-thrusting resulted in the formation of synkinematic NW-dipping non-mineralized quartz veins. D3 upright folding locally steepened the dips of both Au-bearing and non-mineralized quartz veins. Our results may provide new insights into the structural controls of gold mineralization in the XFSO.

Deformed Vein Sets as a Record of Synmetamorphic Volume Change: Quantifying Solution Mass Transfer in Subduction‐Type Metasediments of the Del Puerto Canyon Region, Franciscan Belt, USA

AbstractThe volume change component of deformation is often ignored or assumed to be zero in tectonic studies of metamorphic belts. However, when estimating the original geometries of deformed regions, the volume change is just as important as the other two components of deformation, finite strain, and rotation. Major permanent volume change in metamorphic rocks is accomplished by solution transfer facilitated by H2O fluids and estimates of volume change can be combined with solubilities to provide required time‐integrated volumes of fluid flow. Previously applied methods for estimating rock volume change are based on absolute stretch or changes in whole‐rock chemical compositions. Estimates based on absolute stretches generally indicates large volume reductions whereas geochemical measurements generally imply limited volume change. These contrasting results exist even when the two methods are applied to the same region. In this study, we develop a largely unexplored method for estimating volume change using the direction and deformation type of deformed mineral veins. The assumptions in this method are few and appropriate uncertainties can be estimated. Application of the new method to the metagreywacke in the Del Puerto Canyon of the Franciscan belt constrains the syn‐metamorphic volume change to be greater than 7 vol.%, contrasting with previous proposals for large volume‐loss in the same region. The results of previous studies can be modified by taking into account grain rigid body rotation and grain boundary sliding. The final result of our approach yields a volume change of 7–21vol.% and implies large amounts of water‐rich fluid must have passed through the rock.

Ovarian suspension loop: an assembled device for ovarian lifting and immobilization during laparoscopic cystectomy

The mobility and smooth surface of the ovaries can pose a challenge during laparoscopic cystectomy, with difficulties in manipulation and visualization. We describe assembling a device for ovarian lifting and immobilization that utilizes a nylon suture and a “scalp vein set” to create a loop. The loop can be passed into the pelvic cavity and then slid beneath the ovary, elevating and stabilizing it during surgery without the need to puncture the ovarian tissue or grabbing and damage the utero-ovarian infundibulopelvic ligaments. This device is inexpensive, and its components are easily accessible. This assembled device prevents repetitive falling of the ovary into the pelvic cavity, facilitates laparoscopic ovarian cystectomy, and saves operative time.

Fracture stratigraphy of Mesozoic platform carbonates, Agri Valley, southern Italy

AbstractThe Viggiano Mt. platform carbonates form a layered succession cross-cut by a dense array of pressure solution seams, and five sets of fractures and veins, which together form a sub-seismic structural network associated with polyphasic tectonic evolution. To assess the influence exerted by depositional and diagenetic heterogeneities on fracture geometry, distribution and multiscale properties, we present the results of stratigraphic, petrographic, mineralogical and mesoscale structural analyses conducted at the Viggiano Mountain, southern Italy. Based on rock textures and fossil associations, we documented that the Sinemurian–Pleinsbachian carbonates were deposited in a low-energy open lagoon, the Toarcian carbonates in a ramp setting rimmed by sand shoals, and the Cenomanian carbonates in a medium- to high-energy, lagoonal–tidal setting. Fracture-density (P20) and intensity (P21) values computed after circular scanline measurements show similar trends in both Sinemurian–Pleinsbachian and Toarcian carbonates, consistent with the bed and bed-package heterogeneities acting as efficient mechanical interfaces during incipient faulting. On the other hand, P20 and P21 do not show very similar variations throughout the Cenomanian carbonates due to pronounced bed amalgamation. Throughout the study area, the aforementioned parameters do not vary in proportion to the bed thickness, and show higher values within the coarse-grained carbonate beds. This conclusion is confirmed by results of linear scanline measurements, which focus on the P10 properties of the most common diffuse fracture set. The original results reported in this work are consistent with burial-related, physical–chemical compaction and cementation processes affecting the fracture stratigraphy of the Mesozoic platform carbonates.

Tourmaline and zircon trace the nature and timing of magmatic-hydrothermal episodes in granite-related Sn mineralization: Insights from the Libata Sn ore field

AbstractThe Bin Yauri-Libata polymetallic ore district is a Sn and Au ore-bearing district in the Zuru schist belt, Northwestern Nigeria. The Libata Sn ore field is characterized by a set of cassiterite-bearing hydrothermal veins associated with Neoproterozoic Pan-African granites affected by deformation and low-grade metamorphism. The hydrothermal alteration associated with cassiterite-bearing quartz veins in the Libata deposit includes silicification, albitization, chloritization, and potassic alteration. In this study, geochemical and geochronological data from tourmalines and zircons from Sn-bearing lodes, unmineralized and altered granites is applied to reveal the timing, fluid composition, and source of ore-forming materials for tin mineralization in the Libata ore field. Zircon trace element and Hf isotopes [εHf(t) = +4.37 to +10.85] reveal a mantle-derived source with some crustal contribution for the melts forming the Libata Sn-bearing granites. LA-ICP-MS zircon U-Pb dating constrains the magmatic and hydrothermal ages to 650–646 and 649–646 Ma for the Libata granites. Overlapping zircon εHf(t) and 176Hf/177Hf but distinct 176Lu/177Hf and 176Yb/177Hf ratios from magmatic and hydrothermally altered zircons reveal a magmatic source for the hydrothermal fluids which triggered cassiterite deposition in the Libata ore field. Major element chemistry constrain tourmalines from the Libata ore field as schorls that show high alkalis, low-Ca contents, and moderate ☐ values (where ☐ is x-site vacancy). High Li, Zn, and Sn concentrations in tourmaline as well as Li/Sr and Ca-Fe-Mg ratios demonstrate that the tourmaline formed from granite-sourced fluid likely derived from the host Libata granites. Measured δ11B values from the Libata tourmaline range from –15.7‰ to –14.1‰. The δ11B of the mineralizing fluid is estimated to be –13.1 to –11.9‰ for the Libata tourmalines at 400–500 °C and overlaps with averages from fractionated granites worldwide. Therefore, our data show that tourmaline and zircon are useful tracers of magmatic-hydrothermal evolution in rare-metal-bearing granite systems.

The effects of fault-zone architecture, wall-rock competence and fluid pressure variations on hydrothermal veining and gold mineralization along the Sheba Fault, Barberton Greenstone Belt, South Africa

Hydrothermal vein systems illustrate the spatial and temporal evolution of structural permeabilities along the Sheba Fault, the first-order fault structure in the Sheba-Fairview complex of gold mines in the Archaean Barberton greenstone belt. The fault juxtaposes competent Moodies Group metapsammites against rheologically weaker metaturbidites and intercalated serpentinites of the Fig Tree and Onverwacht groups. Strain localization into the weaker lithologies results in the pronounced asymmetric zonation of the fault into a fault core and a fault-damage zone. The fault core in the weaker Fig Tree and Onverwacht lithologies is characterized by the transposition of earlier bedding and pervasive foliation development. In contrast, hydrothermal veining, alteration and mineralization are confined to competent Moodies Group rocks that form the tens of meter wide damage zone in the immediate footwall of the fault core. Vein systems of the Sheba West ore body disclose the multistage evolution of the fluid flow system along the fault. An early phase of crackle-breccia formation and associated carbonate (dolomite) alteration is regionally widespread and largely pre-dates the main phase of gold mineralization. Crackle breccias are overprinted by successive sets of subhorizontal and subvertical extension (mode I) veins, steeply inclined shear veins and moderately-dipping late-stage cataclasites. The orientation and controls of the vein sets demonstrate their formation during (1) progressive NW-SE directed subhorizontal shortening, and (2) waning fluid pressures from lithostatic values (mode I veins) to sub-lithostatic fluid pressures (mode II shear veins and cataclasites). The economic-grade mineralization of the Sheba West ore body relates to an undulation of the controlling Sheba Fault that corresponds to a releasing bend during top-to-the-NW thrusting. The vein systems along the Sheba Fault illustrate the controls of permeability structures as a result of lithological and rheological contrasts, geometric variations (fault bends) and fluid-pressure fluctuations during faulting.

Deep External Fluid Source Along the Gubbio Normal Fault (Italy): Implications for Slip Along the Altotiberina Active Low-Angle Normal Fault System

Fluids play a critical role in fault slip, fault and damage zone development, and the distribution of seismicity in regional fault systems; however, determining the source of fluids within fault damage zones is complicated by superposition of fluid-related fabrics. Clumped isotopes applied to tectonic studies offer an opportunity to distinguish between fluid sources based on temperature and stable isotopic composition. Here we use the clumped isotope geothermometer and field observations and compare them with microstructural analysis to investigate the Gubbio normal-fault (GuF) core, a major SW-dipping epidetachment fault conjugate to the active Altotiberina low-angle normal fault in central Italy. Several distinct calcite vein sets reveal the incorporation of multiple generations of fluids during development of the damage zone. Clumped isotope results from these various precipitation phases record crystallization temperatures ranging from 87–154°C. These temperatures are broadly consistent with the presence of calcite deformation twin types II and III and are higher than estimates of regional peak burial temperatures. Additionally, stable isotope compositions within vein calcite are distinct from published isotopic values of the Apennine sedimentary succession, which constitutes the local bedrock. We propose that these observations suggest hydrothermal fluids migrated from depths greater than 6 km, which requires hydraulic connectivity along structural pathways between the shallow and deep crust, and fluid overpressures. These fluids reach the GuF via migration along the Altotiberina low-angle normal fault plane ​​and they may be either of diagenetic or of deeper subduction origin. We suggest they possibly originated from the proximal retreating Apennine subduction system, implying that subduction processes exert spatial control on the distribution of fluid-assisted normal faulting and related seismicity which is consistent with the co-migration of closely coupled subduction and hinterland extension in the Apennines from Miocene to Present.