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Green beryl and the yellow beryl variety heliodor are well known from the Volyn pegmatite field in Ukraine, and this study presents details of their morphological characteristics. Visible etch pits are characteristic of beryl from this locality. In addition, they may contain an organic matter called kerite. Formation of the etch pits is asso ciated with a fluorine-rich, late-stage fluid phase. Etch pits on the pinacoidal face have a hexagonal outline and a pointed bottom (originating at linear defects) transitioning to etch pits with very steep walls, and they occur in three different orders of magnitude: =500 µm, =50 µm, and 1-3 µm. On the first-order prismatic faces, etch pits with a flat bottom (originating from point defects) or pointed bottom are square to rectangular, the latter oriented parallel or perpendicular to the beryl's c-axis. Flat bottom etch pits are more abundant than pointed bottom and also occur in three different orders of magnitude. In addition, small etch pits with a canoe shape and porosity on the nanometer scale were observed. Scanning electron microscopy of these etch pits was used to distinguish uncut stones from other pegmatitic beryls, but these phenomena are also visible with an optical microscope or even with a loupe. [ABSTRACT FROM AUTHOR]

Metabasic rocks of the ophiolitic sequences of the Glockner Nappe and Eclogite Zone in the south-central Tauern Window, Austria, reveal important insights into rifting and spreading of the Alpine Tethys. U–Pb dating of magmatic zircons yields a concordant 157 ± 2 Ma crystallization age for the precursor of a coarse-grained metagabbro from the Glockner Nappe. The Late Jurassic intrusion age is coeval with mafic plutonic activity in the Western and Central Alps. Although Penninic ophiolitic sequences in tectonic windows of the Eastern Alps are usually disrupted, an ocean–continent transition setting can be reconstructed for the Glockner Nappe, similar to many ophiolites in the Liguria–Piemont domain in the Western and Central Alps. Together, these observations strongly suggest a formation in the Liguria–Piemont branch of the Alpine Tethys and are inconsistent with a formation in the Valais domain. This finding has important implications for paleogeographic reconstructions of the Penninic realm in the Eastern Alps. Whereas the Glockner Nappe metagabbro and metabasalts clearly reveal their depleted mantle origin, the metabasic rocks of the Eclogite Zone record a more complex formation history involving depleted mantle melting and crustal assimilation in a continental margin setting. [ABSTRACT FROM AUTHOR]

We investigated emerald, the bright-green gem variety of beryl, from a new locality at Kruta Balka, Ukraine, and compare its chemical characteristics with those of emeralds from selected occurrences worldwide (Austria, Australia, Colombia, South Africa, Russia) to clarify the types and amounts of substitutions as well as the factors controlling such substitutions. For selected crystals, Be and Li were determined by secondary ion mass spectrometry, which showed that the generally assumed value of 3 Be atoms per formula unit (apfu) is valid; only some samples such as the emerald from Kruta Balka deviate from this value (2.944 Be apfu). An important substitution in emerald (expressed as an exchange vector with the additive component Al2Be3Si6O18) is (Mg,Fe2+)NaAl–1□–1, leading to a hypothetical end-member NaAl(Mg,Fe2+)[Be3Si6O18] called femag-beryl with Na occupying a vacancy position (□) in the structural channels of beryl. Based on both our results and data from the literature, emeralds worldwide can be characterized based on the amount of femag-substitution. Other minor substitutions in Li-bearing emerald include the exchange vectors LiNa2Al–1□–2 and LiNaBe–1□–1, where the former is unique to the Kruta Balka emeralds. Rarely, some Li can also be situated at a channel site, based on stoichiometric considerations. Both Cr- and V-distribution can be very heterogeneous in individual crystals, as shown in the samples from Kruta Balka, Madagascar, and Zimbabwe. Nevertheless, taking average values available for emerald occurrences, the Cr/(Cr+V) ratio (Cr#) in combination with the Mg/(Mg+Fe) ratio (Mg#) and the amount of femag-substitution allows emerald occurrences to be characterized. The "ultramafic" schist-type emeralds with high Cr# and Mg# come from occurrences where the Fe-Mg-Cr-V component is controlled by the presence of ultramafic meta-igneous rocks. Emeralds with highly variable Mg# come from "sedimentary" localities, where the Fe-Mg-Cr-V component is controlled by metamorphosed sediments such as black shales and carbonates. A "transitional" group has both metasediments and ultramafic rocks as country rocks. Most "ultramafic" schist type occurrences are characterized by a high amount of femag-component, whereas those from the "sedimentary" and "transitional" groups have low femag contents. Growth conditions derived from the zoning pattern—combined replacement, sector, and oscillatory zoning—in the Kruta Balka emeralds indicate disequilibrium growth from a fluid along with late-stage Na-infiltration. Inclusions in Kruta Balka emeralds (zircon with up to 11 wt% Hf, tourmaline, albite, Sc-bearing apatite) point to a pegmatitic origin. [ABSTRACT FROM AUTHOR]

Describes an electrolyte for anodic oxidation of indium phosphate. Applications of III/V compound semiconductors; Overview on the experiment; Electrolytes used in the experiment.

Metal contacts on semiconductors devices are normally defined by lift-off process, because no well-defined etch processes exist for some rare metals. In this work, an RIE process for gold contacts is introduced which requires a high-density plasma, generated by electron cyclotron resonance. The proof is given by the residual-free etching without fence-generation and micromasking in the vicinity of the mask. [ABSTRACT FROM AUTHOR]

The Volyn pegmatites from Volodarsk-Volynskyi in the Zhytomyr Oblast, NW Ukraine, are associated with granites genetically related to the Paleoproterozoic Korosten pluton. Their late-stage evolution is characterized by the formation of opal-cemented breccia. A polymineralic pseudomorph after beryl within the breccia includes bertrandite (±euclase) + F-muscovite (with tobelite component) + buddingtonite + organic matter (OM) + opal (+ traces of K-feldspar, albite, columbite, FeS2, barite, REE-minerals). Sector-zoned and platy to fibrous buddingtonite has variable (K[sup +]Na)- vs. NH4-contents (electron microprobe analyses) and some H2O or H3O[sup +], as indicated by microscope infrared spectroscopy. We suggest that ammonium was produced by decay of OM, which is partly preserved in the pseudomorph. Energy-dispersive electron microprobe data of the OM show with increasing O-decreasing C-N-content due to degassing; the OM contains the high field strength elements Zr (≤7 at%), Y (≤3 at%), Sc (≤0.8 at%), REE (≤0.3 at%), Th (≤0.2 at%), and U (≤1.25 at%), which increase with increasing O-content. Transmission electron microscopy of the OM confirms the presence of N; Zr, Si, and O (with other HFSE) are concentrated in nanometer-sized areas and at the transition from OM to opal in nanometer-sized platy Zr-Si-O crystals. C-rich areas are amorphous but show poorly developed lattice fringes. OM is present in the pseudomorph also as brown pigmentation of opal and in pegmatitic beryl from Volyn as a component in late stage fluid inclusions, identified by C-H vibrational bands in infrared spectra. Stable isotope investigations of C and N of buddingtonite, black opal and kerite (fibrous OM known from the literature to occur in the Volyn pegmatites and interpreted as microfossils) indicate a biogenic origin of the OM. We propose that OM in the pseudomorph is condensed kerite, which achieved the high concentrations of high field strength elements via fluid-pegmatite interaction. Although no age determination of minerals in the pseudomorph is available, textural arguments and phase equilibria indicate its formation in a late stage of the pegmatite evolution, at P-T conditions below ~100 MPa/150 °C. We favor a conceptual model for the formation of the Volyn buddingtonite in analogy to Phanerozoic occurrences of buddingtonite, where over and around the shallow anorthositegranite Korosten pluton hydrothermal convection cells introduced N-bearing hydrocarbons and its precursors into the cooling igneous rocks. Due to the elevated temperature, the OM disintegrated into degassing volatile and non-volatile residual components analogous to petroleum maturation. Organic N, released as NH4, was then incorporated into buddingtonite. [ABSTRACT FROM AUTHOR]

Introduces a spin-on diffusion technique for the improvement of shallow p[sup+] diffusion into InGaAsP. Advantage of the spin-on diffusion technique; Details of the experimental techniques used.

The occurrence of a trioctahedral analog of illite, the dioctahedral interlayer-deficient K-mica, has long been debated. Due to the inherent difficulties of determining structure and chemical composition of the extremely fine-grained material, earlier descriptions based on separated material are equivocal. Here we describe low-temperature (diagenetic) formation of fluorophlogopite, which is interlayer-deficient and therefore analogous to illite, using high-resolution in situ methods (transmission electron microscopy, TEM, with preparation by focused ion beam milling, combined with wavelength-dispersive analysis by field-emission gun electron microprobe). The average composition is K0.5Mg2.8V0.01Fe0.005 [Si3.15Al0.85O10 (OH) 0.65F1.35], including minor amounts of NH4 for charge compensation as determined by electron energy loss spectroscopy. The K-deficient Mg-mica occurs in layer packages of ~10 layers, and no indications for interlayering with other sheet silicate layers such as chlorite or vermiculite could be identified with TEM. X-ray powder diffraction patterns of separated material confirm the absence of smectite components. The mineral was identified in phosphorites from the lowermost Cambrian Tal Group, Mussoori Syncline, Lesser Himalayas, India. The rocks are alternating phosphatic mudstones and phosphatic dolostones, at times interbedded with phosphate-poor carbonate layers, which are rich in organic matter. Sedimentary fluorophlogopite occurs in both rock types and in two textural associations; one in vesicles filled with amorphic organic matter, the other as reaction rims around illite, which contains up to 5 wt% V2O3 in its rims. Textural arguments favor an early diagenetic formation of both, V-bearing illite and fluorophlogopite, closely associated with organic matter and linked to dolomitization. The high-F content stabilizes phlogopite to low temperatures. Our findings confirm that the stability field of fluorophlogopite extends from magmatic to metamorphic and sedimentary conditions. [ABSTRACT FROM AUTHOR]

The N-S running Espinhaço fold belt, situated in the São Francisco craton in central-eastern Brazil, separates this craton in a western and an eastern part along the Paramirim Corridor, a Brasiliano-Panafrican (~650-500Ma) deformation zone. The (meta)sediments of the Espinhaço basin consist of several synthems with dominantly siliciclastic deposits. Among them, Al- and P-rich, lazulite-bearing blue quartzite, the amphibolite-facies equivalent of a phosphatic sandstone, of the Veredas Formation in the Northern Espinhaço form a conspicuous horizon. Zircon crystals from these quartzites have been dated using laser ablation inductively coupled plasma mass spectrometry. The zircon crystals are both detrital and metamorphic in origin, the latter exhibiting highly unusual textures produced by dissolution-reprecipitation reaction and concomitant replacement of metamict areas: (REE, Y, Th, U) zircon+fluid=zircon+xenotime. Detrital zircons reveal relict age groups of 3.1-3.3Ga, 2.6-2.7Ga, 2.0-2.3Ga, and 1.5Ga. The end of sedimentation and erosion of the magmatic and metamorphic rocks of the Sao Francisco craton can be estimated therefore as ≤1.5Ga. The major metamorphic event recorded by reprecipitated zircon is Neoproterozoic and documented by a lower-intercept age of 634±19Ma, which was calculated from analyses of individual spots on19 grains with a common relict Orosirian-Rhyacian age of 2032±31Ma, temporal equivalent to Transamazonian. The Neoproterozoic age of the metamorphosed zircons of the Vereda formation corresponds to the Brasiliano-Panafrican remobilization of the São Francisco-West Congo craton along the eastern side of the Espinhaço fold belt in the Paramirim Corridor. [ABSTRACT FROM AUTHOR]

Highlights: [•] Secondary minerals preferentially accumulate on corroding surfaces. [•] Pore space of porous filter materials only partly filled with precipitates. [•] Complete conversion of ferric minerals to magnetite. [ABSTRACT FROM AUTHOR]

Highlights: [•] In situ dated zircons define Saharan Metacraton and Nubian Shield boundary. [•] We propose extension of the Bayudian Event to 900–1000Ma period. [•] Sr–Pb isotope separate juvenile and cratonic sources for Bayuda metagranitoids. [•] Peak of subduction magmatic–metamorphic activity occurred around 820–780Ma. [•] The final terranes collision occurred between 714Ma and 630Ma. [Copyright &y& Elsevier]

Trace element distribution in titanite overgrowths on rutile has been investigated experimentally at 600 °C, 400 MPa and f near NiNiO buffer. Compositionally homogenous Cr- or Nb-doped synthetic rutile single crystals or Nb-containing natural rutile crystals were the source of Cr, Nb and Ti to synthesize titanite using the double-capsule technique. All element exchange with the source of Si, Ca and Al occurred via a NaCl-HO fluid. Titanite forms quickly and exclusively around the rutile crystals. The titanite overgrowth separates rutile from the bulk fluid, and all elements from rutile dissolution have to pass through the titanite rim. Trace element concentrations in titanite show a considerable scatter in experiments with and without Al, although the average concentrations of Cr or Nb of titanite around compositionally homogeneous synthetic rutile approach the expected values for closed system conditions. Variability of Al with Cr or Nb in the titanite is not correlated. The Al zoning is irregular and patchy, and also the distribution of trace elements does not show systematic trends in the spatial distribution. In experiments using zoned natural rutile, the concentrations of Nb in titanite are related to the Nb zoning in rutile, but the contents also vary unsystematically. Under the controlled conditions of the experiment, the explanation for the strongly irregular spatial distribution is most likely due to variations in elemental concentrations during transport from the rutile along the titanite grain boundaries. The transport pathway is complex because grain boundary migration is important during titanite growth. Such irregular element distribution is also found in a natural sample of titanite overgrowth on rutile from an eclogite with retrograde overprint in the amphibolite facies. Transport of Ti and trace elements was focused on grain boundaries and shielded from the rutile as a source of these elements. We conclude that this type of zoning is not related to changes in P-T or composition in an open system, but solely controlled by transport in and through the titanite rim. [ABSTRACT FROM AUTHOR]

Fluid-assisted mass transport reactions by dissolution-precipitation, where a precursor mineral reacts with a fluid, play an important role in metamorphism and metasomatism. We investigated titanite growth on rutile in time series experiments between one and 107 days at constant P-T conditions of 600 °C and 400 MPa in the system TiO2-CaO-SiO2-Na2O-HCl-H2O. A two-capsule assemblage allows for transport of Ca and Si from dissolving wollastonite to dissolving rutile, the Ti-source, in a NaCl-bearing aqueous fluid, according to the general reaction CaSiO3 + TiO2 = CaTiSiO5. Complete overgrowth of rutile by titanite occurred after just one day of experiment. Fine-grained lozenge-shaped titanite crystals of short-time runs (up to 14 days) reorganize to larger predominantly prismatic crystals after >14 days. After investigation by scanning electron microscopy, the titanite overgrowth was removed from the rutile by hydrofluoric acid, to provide a three-dimensional view of the dissolution-reaction front on the rutile surface. The morphology of the rutile surface is dominated by humps or ridges beneath the central region of a titanite crystal and valleys at the grain boundaries between adjacent titanite crystals. The dissolution pattern on the rutile surface mimics the titanite overgrowth and changes with changing grain size and shape of the titanite with longer run times. The preferred dissolution of rutile in the valleys is clearly linked to the position of the titanite grain boundaries, which served as pathways for fluid-assisted element transport. Rutile-titanite and titanite-titanite boundaries show a significant porosity in transmission electron microscopy images of foils prepared by focused ion beam milling. The large-scale dissolution pattern on the rutile surface is independent of the crystallographic orientation of the rutile and entirely dominated by the arrangement of titanite crystals in the overgrowth. Dissolution features on a scale smaller than ~1 µm are dominated by stepwise dissolution and etch-pits following the crystallographic orientation of the rutile. Similar observations were made in experiments with an additional Al-source, although these experiments result in a different overgrowth pattern; i.e., an exposed rutile surface is always present and solitary titanite crystals are accompanied by partial overgrowths. Quantitative characterization of the surface morphology by white-light interference microscopy demonstrates that, with increasing grain size of titanite, dissolution of rutile is strongly enhanced at the titanite grain boundaries. Natural examples of titanite overgrowths on rutile show the same relations between element pathways, arrangement of titanite crystals and 3D dissolution pattern on rutile as in the experimental systems. We conclude that the transport of Ti away from the rutile and of Ca + Si into the reaction rim occurred in a grain boundary fluid, the composition of which must have been strongly different from the composition of the bulk fluid in the experiment, as well as in the natural system. The reaction progress depends on the availability of a fluid, and relicts of rutile in titanite indicate restricted availability of fluid in the natural system (e.g., a fluid pulse that was consumed by the reactions). The reaction examined here can serve as a proxy for other reactions of the conversion of oxide minerals (e.g., spinel or corundum) into silicates. [ABSTRACT FROM AUTHOR]

The isotopic composition of mafic small-volume intra-plate magmatism constrains the compositions of the sub-continental mantle sources. The Nd, Pb, and Sr isotope signatures of widespread late Mesozoic to Quaternary intra-plate magmatism in NE Africa (Sudan, South Egypt) are surprisingly uniform and indicate the presence of a high-μ (μ = 238U/204Pb) source in the mantle. The rocks are characterized by small ranges in the initial isotopic composition of Nd, Pb, and Sr and most samples fall within ε Nd ca. 3–6, 206Pb/204Pb ca. 19.5–20.5, 207Pb/204Pb ca. 15.63–15.73, 208Pb/204Pb ca. 39–40 and 87Sr/86Sr ca. 0.7028–0.7034. We interpret this reservoir as lithospheric mantle that formed beneath the Pan-African orogens and magmatic arcs from asthenospheric mantle, which was enriched in trace elements (U, Th, and light REE). Combining our new data set with published data of intra-plate magmatic rocks from the Arabian plate indicates two compositionally different domains of lithospheric mantle in NE-Africa–Arabia. The two domains are spatially related to the subdivision of the Pan-African orogen into a western section dominated by reworked cratonic basement (NE-Africa; high-μ lithospheric mantle) and an eastern section dominated by juvenile Pan-African basement (easternmost NE-Africa and Arabia; moderate μ lithospheric mantle). The compositions of the Pan-African lithospheric mantle and the MORB-type mantle of the Red Sea and Gulf of Aden spreading centers could explain the Nd–Pb-Sr isotopic compositions of the most pristine Afar flood basalts in Yemen and Ethiopia by mixtures of the isotopic composition of regional lithospheric and asthenospheric sources. [ABSTRACT FROM AUTHOR]

Abstract: The Late Triassic Cobquecura Pluton is a small epizonal intrusive body that was emplaced into the Paleozoic Basement at the western side of the Cordillera de la Costa, near to the town of Cobquecura (35°57′–36°12′S, central Chile). The pluton displays a wide spectrum of compositions that include gabbro and fayalite-granite, and less abundant hybrid rocks. SiO2-content ranges from 48 to 76 wt.% with a compositional gap between 57 and 63 wt.% SiO2. SiO2-poor rocks have Mg–Fe minerals olivine (Fa33–34), diopside‑augite (Mg#=56–91; Mg#=(Mg/(Mg+Fe2+)×100) and pargasite (Mg#=4–8), which with progressive differentiation become Fe-rich olivine (Fa89–98), hedenbergite–ferroaugite (Mg#=10–43) and ferroedenite (Mg#=8–29). Similar K/Ar isotopic ages, mingling structures, and coherent arrays in Harker diagrams, as well as mineral compositions show that the SiO2-poor and SiO2-rich rocks are comagmatic. The Fe-rich mineralogy and Ga-content of the Cobquecura Pluton point to an anorogenic A-type magmatism. The compositional similarities, as well as the bimodal character of the magmatism of Cobquecura and other Upper Triassic granitoids and lavas north of 30°S at the Chilean continental margin indicate a common origin of the magmatism with anorogenic signature and coeval processes along the southwestern margin of Gondwana in the Triassic. [Copyright &y& Elsevier]

The XeCI* excimer laser is a well-established system tool for many applications. During operation, highly volatile chlorides are often formed, which leads to enhanced electrode erosion and reduced lifetime. Therefore, special attention should be paid to the rate of erosion of all electrode materials that are used in chlorine based excimer lasers. In our work, we came to the result that the chemical behavior of the electrode material is much more important than the classical electrode parameters erosion rate and work function. To separate the erosion rate into a chemical and physical part, we used a nickel electrode as anode (almost no wear) and cathode (low wear compared to tungsten). We concluded that nickel as an electrode material is still the best material in our laser design. [ABSTRACT FROM AUTHOR]

Abstract: Sr–Nd–Pb isotope ratios of alkaline mafic intra-plate magmatism constrain the isotopic compositions of the lithospheric mantle along what is now the eastern foreland or back arc of the Cenozoic Central Andes (17–34°S). Most small-volume basanite volcanic rocks and alkaline intrusive rocks of Cretaceous (and rare Miocene) age were derived from a depleted lithospheric mantle source with rather uniform initial 143Nd/144Nd (∼0.5127–0.5128) and 87Sr/86Sr (∼0.7032–0.7040). The initial 206Pb/204Pb ratios are variable (18.5–19.7) at uniform 207Pb/204Pb ratios (15.60±0.05). A variety of the Cretaceous depleted mantle source of the magmatic rocks shows elevated Sr isotope ratios up to 0.707 at constant high Nd isotope ratios. The variable Sr and Pb isotope ratios are probably due to radiogenic growth in a metasomatized lithospheric mantle, which represents the former sub-arc mantle beneath the early Palaeozoic active continental margin. Sr–Nd–Pb isotope signatures of a second mantle type reflected in the composition of Cretaceous (one late Palaeozoic age) intra-plate magmatic rocks (143Nd/144Nd∼0.5123, 87Sr/86Sr∼0.704, 206Pb/204Pb∼17.5–18.5, and 207Pb/204Pb∼15.45–15.50) are similar to the isotopic composition of old sub-continental lithospheric mantle of the Brazilian Shield. Published Nd and Sr isotopic compositions of Mesozoic to Cenozoic arc-related magmatic rocks (18–40°S) represent the composition of the convective sub-arc mantle in the Central Andes and are similar to those of the Cretaceous (and rare Miocene) intra-plate magmatic rocks. The dominant convective and lithospheric mantle type beneath this old continental margin is depleted mantle, which is compositionally different from average MORB-type depleted mantle. The old sub-continental lithospheric mantle did not contribute to Mesozoic to Cenozoic arc magmatism. [Copyright &y& Elsevier]

The etching of the complete Bell contact consisting of a layer of Ti/Pt/Au was performed in highly reactive plasmas containing Cl2 for Ti, PF3/NF3 for Pt, and Cl2 and/or BCl3 for Au. All the constituents of the Bell contact form volatile compounds in either capacitively-coupled low-density plasmas or high-density plasmas generated by electron cyclotron resonance. This is conditio sine qua non for surfaces and sidewalls which have to remain free of any residues. [Copyright &y& Elsevier]

Presents a study which measured enthalpies of drop solution in molten lead borate for zoisite and clinozoisite samples spanning epidote solid solutions. Experimental procedure; Results; Discussion.

Intended roughening of SiC can be performed in a one-step procedure (simultaneous generation and tear-off of a temporary mask) or in a two-step process which is far easier to control. A method is described based on the “contamination-induced” mechanism which allows reproducible roughening even of polished surfaces applying a parallel process. It makes use of a very thin layer of silver which is sputtered on top of the SiC surface and subsequently etched by means of a fluorine-containing high-density plasma generated by electron cyclotron resonance. [Copyright &y& Elsevier]

We report an experimental study of an electron cyclotron wave resonance (ECWR) plasma source. The dimensions of the source are considerably larger than in similar experiments. The excitation frequency is 27.12 MHz, the working gas is argon at very low pressures below 0.13 Pa. Spectroscopic data connected with a global model yield electron temperature $T_{\mathrm{ e}}$ , electron number density $n_{\mathrm{ e}}$ , population of the metastable state $n_{\mathrm{ m}}$. The pressure dependencies of these quantities are discussed. Starting from $T_{\mathrm{ e}}\sim 5$ eV at pressure $p=0.13$ Pa the temperature grows as the pressure goes down until the discharge extinguishes at ${\sim }0.6\times 10^{-2}$ Pa. It becomes in the meantime so high that the emission spectra feature strong Ar(II) lines in the region 400–500 nm. At $p=0.13$ Pa and power 300 W the electron density on the axis is about $4\times 10^{10}~{\mathrm{ cm}}^{-3}$ and falls down due to the increase in $T_{\mathrm{ e}}$ as the pressure drops. The discharge was also electrically characterized to determine the plasma impedance $Z$. The impedance and the plasma resistance ${\mathrm{ Re}}(Z)$ are presented as functions of the static magnetic field $B_{\mathrm{ 0}}$. The distribution of power losses are also shown as $B_{\mathrm{ 0}}$ -dependencies. [ABSTRACT FROM AUTHOR]

Metaigneous mafic and ultramafic rocks from the juvenile Neoproterozoic Arabian Nubian Shield (ANS) and the Proterozoic, reworked Saharan Metacraton (SMC) have been analysed for major- and trace elements and Sr, Nd, and Pb isotopes. Most of the rocks are amphibolites metamorphosed at amphibolite facies conditions, some with relicts of a granulite facies stage. The other rocks are metapyroxenites, metagabbros, and some ultramafic rocks. Trace element compositions of the metabasaltic (dominantly tholeiitic) rocks resemble the patterns of island arcs and primitive lavas from continental arcs. Variable Sr and Nd isotope ratios indicate depleted mantle dominance for most of the samples. 207 Pb/ 204 Pb signatures distinguish between the influence of high 207 Pb/ 204 Pb old SMC crust and depleted mantle signatures of the juvenile ANS crust. The Pb isotope signatures for most metabasaltic rocks, metapyroxenites and metagabbros from SMC indicate an autochthonous formation. The interpretation of the new data together with published evidence from mafic xenoliths on SMC and ophiolite from ANS allows an extrapolation of mantle evolution in time. There are two lines of evolution in the regional mantle, one, which incorporates potential upper crust material during Neoproterozoic, and a second one with a depleted mantle signature since pre-Neoproterozoic that still is present in the Red Sea and Gulf of Aden spreading centres. [ABSTRACT FROM AUTHOR]

Chemical zoning according to the substitution Al + (OH,F) = Ti + O is a common phenomenon in natural titanite and can be used to reconstruct its growth conditions. We synthesized titanite, which has a zoning pattern similar to that found in natural titanite that grew at the expense of rutile, visible in element distribution maps as a patchy irregular pattern. Run conditions in the system CaO-Al2O3-TiO2-SiO2-NaCl-H2O(-CaF2) were 600 °C, 0.4 GPa, 1 to 107 days duration. Natural rutile crystals were placed in a perforated Pt-tube within an outer Au-capsule containing wollastonite, γ-Al2O3, optionally powdered CaF2, and a NaCl brine, to simulate conditions, where rutile is transformed into titanite by a hydrous Ca-Si-Al(-F) fluid, driven by a chemical potential gradient between inner and outer capsule. Spontaneous nucleation of titanite is restricted to a small number of crystals on the rutile surface in the inner capsule. Growth proceeds from sparse isolated titanite crystals after 1 day to assemblages of several 100 µm large crystals in a reaction rim in the long-time runs. Titanite is strongly zoned in Al-Ti and shows up to ~0.5 Al per formula unit (pfu) in experiments containing F; without F, substitution is limited to ~0.25 Al pfu. The range of the Ti-Al exchange is already large in short run times and the same heterogeneity is observed in long-time runs. The Al-Ti distribution (with and without F) in compositional domains (up to several tens of micrometers) is patchy and irregular. No relation of the zoning with time (core-rim) or preferred growth directions was observed. In the case of fluid-mediated growth, mineral growth zoning represents a disequilibrium at supersaturated conditions. The concentration of Ti in the fluid is likely the limiting factor for titanite growth considering the low solubility compared to that of Al, Ca, and Si. Titanium is not transported in significant amounts into the outer capsule, indicating low mobility, in contrast to Al, Ca, and Si, which are transported into the inner capsule. Assuming buffered Al concentration from dissolution of the Al-source, we speculate that the Ti/Al of the fluid at the precipitation site was controlled by the local Ti concentration, which varies over the distance from the rutile surface to the growing titanite crystal and produces the irregular patchy zoning. [ABSTRACT FROM AUTHOR]

The Ca-Sr fractionation between zoisite and, respectively, lawsonite and an aqueous fluid has been determined by synthesis experiments in the presence of a 1 M (Ca,Sr)Cl2 aqueous fluid at 2.0 GPa/550, 600, and 700 °C and 4.0 GPa/800 °C for zoisite and 2.0 GPa/400 °C and 4.0 GPa/600 °C for lawsonite. Solid run products were characterized by EMP, SEM, and XRD with Rietveld refinement and fluids were analyzed by ICP-OES. Zoisite exhibits notable intracrystalline Ca-Sr fractionation between the A1 and A2 sites and calculated intracrystalline exchange coefficients KD(Sr-Ca)A1-A2 = 1.5 to 26 show strong preference of Sr over Ca for the slightly larger A2 site. Calculated individual site-dependent zoisite/aqueous fluid (af, in superscripts)-exchange coefficients for the studied 1 M (Ca,Sr)Cl2 aqueous fluids are K(Sr-Ca)zo A1-af = 3.38 to 41.08 for the A1 site and K(Sr-Ca)zo A1-af = 0.45 to 6.51 for the A2 site. Assuming γCaaf = γSraf and a symmetric mixing model, the thermodynamic evaluation of the site-dependent exchange reactions Ca2+(af) + SrA1(M2+)A2 Al3[Si3O11(O/OH)] = Sr2+(af) + CaA1 (M2+)A2Al3[Si3O11(O/OH)] and Ca2+(af) + (M2+)A1 SrA2 Al3[Si3O11(O/OH)] = Sr2+(af) + (M2+)A1 CaA2 Al3[Si3O11(O/OH)] yields Δµ0 = --29 kJ/mol and WSr-Cazo A1 = 5.5 kJ/mol for the A1 site and Δµ0 = -1.1 kJ/mol and WSr-Cazo A2 = 0 kJ/mol for the A2 site at P and T of the experiments. The data indicates ideal Ca-Sr substitution on the A2 site. Lawsonite formed in both the orthorhombic Cmcm and the monoclinic P21/m form. Calculated lawsonite-aqueous fluid-exchange coefficients indicate overall preference of Ca over Sr in the solid and are KD(Sr-Ca)law Cm -cm-af = 1.12 to 11.32 for orthorhombic and KDD(Sr-Ca)law Cm -cm-af = 1.67 to 4.34 for monoclinic lawsonite. Thermodynamic evaluation of the exchange reaction Ca2+(af) + SrAl2Si2O7(OH)2·H2O = Sr2+(af) + CaAl2Si2O7(OH)2·H2O assuming γCaaf = γSraf and a symmetric mixing model yields similar values of Δµ0 = --9 kJ/mol and WSr-Calaw Cmcm-af = 10 kJ/mol for orthorhombic and Δµ0 = -10 kJ/mol and WWSr-Calaw P21/m = 11 kJ/mol for monoclinic lawsonite. Calculated Nernst distribution coefficients for the studied 1 M (Ca,Sr)Cl2 aqueous fluids are DSrzo-af = 2.8 ± 0.7 for zoisite at 2 GPa/600 °C and DSrlaw Cmcm-af = 0.6 ± 0.2 for orthorhombic lawsonite at 4 GPa/600 °C and show Sr to be compatible in zoisite but incompatible in lawsonite. This opposite mineral-aqueous fluid-fractionation behavior of Sr with respect to zoisite and lawsonite on the one hand and the ideal Ca-Sr substitution on the zoisite A2 site in combination with the strong intracrystalline Ca-Sr fractionation in zoisite on the other hand, make Sr a potential tracer for fluid-rock interactions in zoisite- and lawsonite-bearing rocks. For low Sr-concentrations, xSrzo directly reflects xSraf and allows us to calculate Sr-concentrations in a metamorphic aqueous fluid. During high-pressure aqueous fluid-rock interactions in subduction zone settings the opposite mineral-aqueous fluid-fractionation behavior of Sr results in different aqueous fluid characteristics for lawsonite- vs. zoisite-bearing rocks. Ultimately, subduction zone magmas may trace these different aqueous fluid characteristics and allow distinguishing between cold, lawsonite-bearing vs. warm, zoisite-bearing thermal regimes of the underlying subduction zone. [ABSTRACT FROM AUTHOR]

Aerial parts of Daphne pontica were collected from Ilgaz-Çankırı, and D. oleoides subsp. oleoides was collected from 2 different localities (Ayrancı-Karaman and Ilgaz-Çankırı) in Turkey. The samples were subjected to hydrodistillation and microdistillation. The resulting volatile samples were analyzed both by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS), respectively. The main components for D. pontica were identified as hexahydrofarnesyl acetone (8.6%), carvacrol (8.5%), dihydroedulane II (4.7%), (E)-geranyl acetone (4.6%), and thymol (4.5%), while nonacosane (42.5% and 27.2%), hexadecanoic acid (24.4% and 20.0%), phytol (12.3%), and carvacrol (5.0%) were identified as the main components of D. oleoides subsp. oleoides obtained by hydrodistillation. Carvacrol (12.0%), thymol (7.7%), dihydroactinidiolide (7.2%), bicyclosesquiphellandrene (5.5%), and (Z)-3-hexenal (4.1%) were the major components in D. pontica, while carvacrol (27.2% and 25.4%), nonacosane (24.6%), (Z)-3-hexenal (18.5% and 2.5%), decane (7.4%), hexahydrofarnesyl acetone (7.4% and 2.2%), hexanal (6.6% and 1.5%), heptacosane (6.1%), nonanal (5.6% and 1.9%), thymol (5.1% and 2.3%), and phytol (5.0%) were identified in the D. oleoides subsp. oleoides isolated by microdistillation, respectively. In addition, the volatile components were evaluated for their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals using a bioautographic thin layer chromatography (TLC) method, and the samples showed activity comparable with that of the tested standards, vitamins C and E. [ABSTRACT FROM AUTHOR]

The evolution of the Early Palaeozoic orogen of West Gondwana in the Cambrian to Ordovician basement of the Andes between ~18° and 32° S is investigated for pressure and temperature conditions and age of metamorphism. It is characterized by mid-crust temperatures commonly above the wet granite solidus (~650°C). Widespread felsic migmatite and rare granulite formed at pressures of ca 0.5-0.7 GPa, locally 1.0 GPa. These rocks represent the deepest exhumed sections of the Early Palaeozoic crust. High pressure-low temperature rocks are absent. The crystallization ages, compiled from the literature in combination with new data, for near peak metamorphic conditions of these high-grade metamorphic rocks in NW Argentina and N Chile are ~530-500 Ma and ~470-420 Ma. Both age groups are spatially overlapping. Radiogenic isotope signatures (Sr, Nd, Pb) are used to characterize the Early Palaeozoic basement. The Pb and Sr isotope compositions of the Early Palaeozoic basement indicate mixing arrays between pre-Palaeozoic unradiogenic and radiogenic crust. Crustal residence ages (Sm-Nd T) indicate a prominent event of crust formation around ~2 Ga, which is known continent-wide. This material was recycled during Midproterozoic and Early Palaeozoic orogenies without prominent additions of new crust present in the isotope record, i.e. accretion of compositional exotic material is absent. [ABSTRACT FROM AUTHOR]

New isotopic ages constrain the onset of the Andean Orogeny in central Chile (34°-37°S). They define three pulses of Early Mesozoic magmatism in the Cordillera de la Costa: granitic magmatism at 225-220 Ma, bimodal magmatism at 210-197 Ma, and mafic magmatism at 170-150 Ma. Each pulse has distinct field, petrographic, geochemical, and Sr-Nd-Pb isotopic characteristics and crystallization conditions. Major magmatic sources are the regional Mesozoic subarc-subcontinental mantle and the Paleozoic Chilean continental crust, with the importance of juvenile contributions increasing with time. All three Early Mesozoic magmatic pulses display geochemical signatures that are characteristic of subduction-related magmas of magmatic arcs, such as a Nb-Ta trough and a positive Pb anomaly. The 210-197-Ma magmatism is peculiar for its bimodal nature, the occurrence of transitional A-type granitoids, the presence of fayalite granites, and its association with an episode of crustal extension. A contemporaneous accretionary wedge nevertheless indicates ongoing subduction at that time. The 210-197-Ma magmatic pulse thus was formed in an extensional suprasubduction zone environment. It marks the transition from the Gondwana Orogeny to Andean- style subduction magmatism. We argue that the onset of the Andean Orogeny was related to a reconfiguration of the tectonic conditions of plate convergence during overall near-continuous subduction and arc magmatism since the Paleozoic. [ABSTRACT FROM AUTHOR]

Marine Quaternary trench and slope sediments were sampled along the margin of the Southern Andes, Chile between 36° and 40°S. Major and trace element contents indicate only minor influence of weathering and transport fractionation. The whole rock composition of the sediments is similar to the average rock of the Cretaceous to Holocene magmatic arc of this section of the southern volcanic zone. Sr, Nd, and Pb isotope composition of the sediments also resembles closely the average composition of the magmatic arc. The contribution of compositionally distinct Palaeozoic crust, which makes up most of the volume of the forearc, is ~0–20% crustal Sr, Nd, and Pb according to the isotope record of the trench and slope sediments. Input of sediments from the continent into the subduction system was dominated by detritus from the magmatic arc at least for the last 20 My on the basis of the Oligocene to Holocene exhumation history of the margin. [ABSTRACT FROM AUTHOR]

Abstract: Fayalite granitoids of the Cobquecura Pluton, Central Chile, occur in an active continental margin setting, which is unusual for such rocks. They are closely associated with gabbros, and both lithologies contain hercynite-rich, Fe-rich metapelitic xenoliths. The primitive magmas of the Cobquecura Pluton are derived from a mafic source, similar to the regional subarc subcontinental mantle. Sr–Nd–Pb isotope data demonstrate that crustal contributions were important in the petrogenesis of the fayalite granitoids. The crustal contribution, however, does not consist of rocks similar to the regionally exposed Paleozoic basement rocks, but rather resembles partial melts derived from metapelitic rocks at depth. The corresponding restites are the hercynite-rich xenoliths. A relatively high content of rare earth elements and high field strength elements in the fayalite granitoids is linked to selective assimilation of crust. This is evident from the abundant xenoliths that are entrained in the fayalite granitoids, and whose leucosomes are rich in accessory minerals carrying these elements. Such Fe-rich rocks similar to the hercynite-rich xenoliths could have acted as a chemical buffer keeping the oxygen fugacity low, which is crucial for the generation of fayalite bearing granitoids. [Copyright &y& Elsevier]

We determined experimentally the Nernst distribution coefficient $$ D_{i}^{{{\text{opx}} - {\text{melt}}}} = \frac{{c_{i}^{\text{orthopyroxene}} }}{{c_{i}^{\text{melt}} }} $$ between orthopyroxene and anhydrous silicate melt for trace elements i in the system Na2O–CaO–MgO–Al2O3–SiO2 (NCMAS) along the dry model lherzolite solidus from 1.1 GPa/1,230°C up to 3.2 GPa/1,535°C in a piston cylinder apparatus. Major and trace element composition of melt and orthopyroxene were determined with a combination of electron microprobe and ion probe analyses. We provide partitioning data for trace elements Li, Be, B, K, Sc, Ti, V, Cr, Co, Ni, Rb, Sr, Y, Zr, Nb, Cs, Ba, La, Ce, Sm, Nd, Yb, Lu, Hf, Ta, Pb, U, and Th. The melts were chosen to be boninitic at 1.1 and 2.0 GPa, picritic at 2.3 GPa and komatiitic at 2.7 and 3.2 GPa. Orthopyroxene is Tschermakitic with 8 mol% Mg-Tschermaks MgAl[AlSiO6] at 1.1 GPa while at higher pressure it has 18–20 mol%. The rare earth elements show a continuous, significant increase in compatibility with decreasing ionic radius from D ∼ 0.0008 to D ∼ 0.15. For the high-field-strength elements compatibility increases from D ∼ 0.001 through D ∼ 0.0015, D ∼ 0.002, D ∼ 0.005, D ∼ 0.02 and D ∼ 0.04 to D ∼ 0.14. From mathematical and graphical fits we determined best-fit values for D, D, r, r, E, and E for the two different M sites in orthopyroxene according to the lattice strain model and calculated the intracrystalline distribution between M1 and M2. Our data indicate extreme intracrystalline fractionation for most elements in orthopyroxene; for the divalent cations D varies by three orders of magnitude between D = 0.00098–0.00919 and D = 2.3–28. Trivalent cations Al and Cr almost exclusively substitute on M1 while the other trivalent cations substitute on M2; D reaches extreme values between 6.5 × 107 and 1.4 × 1016. Tetravalent cations Ti, Hf, and Zr almost exclusively substitute on M1 while U and Th exclusively substitute on M2. Our new comprehensive data set can be used for polybaric-polythermal melting models along the Earth’s mantle solidus. [ABSTRACT FROM AUTHOR]

This paper presents new insights on the evolution of continental crust in a segment of the southern Central Andes (Chile–Argentina; ca. 36–41 °S) from compositional and isotopic age data of metamorphic and magmatic rocks. The crustal reservoir of this long-standing active continental margin is characterized by the isotopic composition of Paleozoic (meta)sedimentary rocks which is typical of Proterozoic continental crust (Nd model ages 1.6–2.1 Ga; isotopic composition at ca. 300 Ma, the time of formation of the late Paleozoic granites: 87Sr/86Sr ca. 0.71–0.72; 143Nd/144Nd ca. 0.5117–0.5120; 207Pb/204Pb ca. 15.64–15.70, 206Pb/204Pb ca. 18.2–18.6, 208Pb/204Pb ca. 37.2–38.5). The late Paleozoic and late Triassic granitoids (ca. 220 Ma) contain 30–80% of this material assuming a mantle endmember with the isotopic composition of Pacific MORB. The proposed mechanism of magma generation in the late Paleozoic and Triassic granitoids is assimilation of crustal material by mantle derived melts, i.e. mixing between crustal and mantle melts. The isotopic composition of the Paleozoic rocks in the southern Central Andes indicates a coherent evolution of the western Gondwana margin (21–41°S) during the Paleozoic mainly recycling Proterozoic material by sedimentation, metamorphism and magmatism.The magmatism of the Andean cycle represents important additions of juvenile material to the crust. The Mesozoic to Tertiary intrusions have a relatively uniform isotopic composition (87Sr/86Sri ca. 0.7036–0.7066; 143Nd/144Ndi ca. 0.5125–0.5129; Pbi 207Pb/204Pb ca. 15.60–15.65, 206Pb/204Pb ca. 18.0–18.5, 208Pb/204Pb ca. 37.2–38.4) indicating only small contributions of the crustal reservoir (ca. 5–10%) to mantle derived magma with presumed MORB isotope signature. The proposed main mechanism of crustal contribution in these rocks is mixing of continent-derived sediments into the mantle wedge. [Copyright &y& Elsevier]

Presents the first systematic study of synthetic iron-free and iron-bearing zoisite using X-ray powder diffraction and infrared spectroscopy. Electrone microprobe analysis; Fourier-transform infrared analysis; Lattice parameters and atom coordinates of all of the samples.

Pb-isotope composition of feldspar determined for a suite of granitoid magmatic and metamorphic rocks of Cambrian to Permian age provides a guide to the crustal composition in the Central Andes as it evolved during the Paleozoic. The large range of Pb-isotope composition of magmatic rocks older than 500 Ma contrasts with the homogeneous Pb-isotope composition of magmatic and metamorphic rocks that formed between 500 Ma and the Late Paleozoic. There are four isotopically distinct crustal domains discernible. Three of them, associated with pre-500-Ma-old rocks, are characterised by similar 206Pb/204Pb of ca. 16.6–17.0 and are distinguished from each other by contrasting 207Pb/204Pb and 208Pb/204Pb signatures. We distinguish (i) an unradiogenic source with 207Pb/204Pb of ca. 15.4 and 208Pb/204Pb of ca. 36.5, which may have been the principal source of crustal lead for Cenozoic magmatic rocks north of 21°S, (ii) an old high-μ source with 207Pb/204Pb of ca. 15.8 and 208Pb/204Pb of ca. 36.5–37.5, and (iii) an Arequipa-type source with 207Pb/204Pb of ca. 15.6 and 208Pb/204Pb of ca. 38.5. The fourth crustal lead source, a radiogenic source, is characterised by a relatively small range of Pb-isotope compositions of Paleozoic gneisses of the basement (206Pb/204Pb ca. 18.0–18.8, 207Pb/204Pb ca. 15.55–15.75, 208Pb/204Pb ca. 37.5–38.5) and most intrusions which formed after high-grade metamorphism at ca. 500 Ma. The compositional range given by present day Pb-isotope ratios of the radiogenic source (average values of whole rock Pb-isotope ratios: 206Pb/204Pb 19.10, 207Pb/204Pb 15.70, 208Pb/204Pb 39.02) and the feldspar data (average values: 206Pb/204Pb 18.38, 207Pb/204Pb 15.64, 208Pb/204Pb 38.11), which also represent the present day composition of those parts of the radiogenic source depleted in U at ca. 500 Ma, is clearly reflected in the Pb-isotope ratios of the widespread Cenozoic ignimbrites and andesites from the Central Andes south of 21°S. Rocks of all lead sources have Proterozoic crustal residence ages (tDM=ca. 1.6–2.0 Ga). However, the three sources of little radiogenic 206Pb/204Pb experienced a dominantly metamorphic redistribution of U, Th, and Pb early in their history. The Early Paleozoic major metamorphic–magmatic cycle incorporated these inherited Pb-isotope domains of minor volume into the radiogenic source south of 21°S. [Copyright &y& Elsevier]

Focuses on a study which documented the mineral chemistry and boron-isotope composition of tourmaline in a suite of Palaeozoic to Mesozoic rock samples from the central Andes of Northwest Argentina. Geological setting and sample description; Techniques in analyzing boron isotopes; Chemical composition of whole-rocks and tourmalines.

Carbonates are excellent carriers for divalent cations such as Ca, Mg, and Sr, and knowledge about their stability and solid solutions is important to understanding the global strontium cycle. To shed light on the topology of the two-phase field between calcite-type and aragonite-type (Ca,Sr)CO3 solid solutions as a function of temperature and pressure, and to learn more about the distribution of Sr and Ca between carbonates and fluid, we studied the system CaCO3-SrCO3-H2O at 600 °C in the pressure range 0.5-5 kbar. Conventional and rapid-quench hydrothermal syntheses were performed using a range of different starting materials. All bulk compositions were within the assumed/postulated two-phase field of calcite-type and aragonite-type (Ca,Sr)CO3 solid solutions. The run products were analyzed by scanning electron microscopy, electron microprobe analysis, and powder X-ray diffraction with Rietveld refinement. The results show that the heterotype solid solution is more extensive than previously assumed, with calcite incorporating up to 20 mol% SrCO3, which is twice as much as previously predicted. The compositional range of the aragonite-type solid solution was identical to that found in the literature. Using the data from this study, an updated version of the phase diagram P-X (Sr) at 600 °C for the CaCO3-SrCO3 system was calculated. The phase diagram does not support a phase transition within the trigonal (Ca,Sr)CO3 solid solution associated with rotational disorder of the CO3-groups. This order-disorder phase transition was previously postulated to explain some observed compositional trends in this system. Our new data are in line with other more recent studies. The distribution of Sr and Ca between the fluid and solid phases D = XsolidSr/XfluidSr is near to 1.0 for calcite-type and on average around 2.0 for aragonite-type solid solutions. This contrasts with silicate-fluid systems in which Sr typically shows a strong preference for the fluid phase compared with Ca. [ABSTRACT FROM AUTHOR]

The metastable paragenesis of corundum and quartz is rare in nature but common in laboratory experiments where according to thermodynamic predictions aluminum–silicate polymorphs should form. We demonstrate here that the existence of a hydrous, silicon-bearing, nanometer-thick layer (called "HSNL") on the corundum surface can explain this metastability in experimental studies without invoking unspecific kinetic inhibition. We investigated experimentally formed corundum reaction products synthesized during hydrothermal and piston–cylinder experiments at 500–800 °C and 0.25–1.8 GPa and found that this HSNL formed inside and on the corundum crystals, thereby controlling the growth behavior of its host. The HSNL represents a substitution of Al with Si and H along the basal plane of corundum. Along the interface of corundum and quartz, the HSNL effectively isolates the bulk phases corundum and quartz from each other, thus apparently preventing their reaction to the stable aluminum silicate. High temperatures and prolonged experimental duration lead to recrystallization of corundum including the HSNL and to the formation of quartz + fluid inclusions inside the host crystal. This process reduces the phase boundary area between the bulk phases, thereby providing further opportunity to expand their coexistence. In addition to its small size, its transient nature makes it difficult to detect the HSNL in experiments and even more so in natural samples. Our findings emphasize the potential impact of nanometer-sized phases on geochemical reaction pathways and kinetics under metamorphic conditions in one of the most important chemical systems of the Earth's crust. [ABSTRACT FROM AUTHOR]

Presents a study to assess the value of cerebral magnetic-resonance imaging (MRI) in prediction of recovery from early post-traumatic vegetative state. Methods of assessment using MRI and the Glasgow Outcome Scale; Findings of a link between corpus callosum and dorsolateral brainstem injuries and non-recovery; Interpretation.

• Si isotopes document the appearance of siliceous sponges around Precambrian-Cambrian transition on the submerged, karsted 'Berkuty dolostone' • Cherts transition into silicified granular phosphorites during regression. • Organic matter mineralization in phosphatic facies controls redox-sensitive Ce*. • Reduced sponge abundance during elevated suspended particle concentrations. • Cambrian transgression created favorable condition for sponge proliferation. Ocean oxygenation during the Precambrian-Cambrian transition is thought to be one of the key factors for the rapid diversification of animals, known as the 'Cambrian Explosion'. Siliceous sponges inhabiting continental slope settings were capable of shifting the respiratory oxygen demand in the water column to depth, resulting in an increase in oxygen levels of shallow water. To assess the global importance of the impact of ecosystem engineering by sponges, we evaluated the palaeo-environmental conditions that confine sponge expansion using multiple geochemical proxies including silicon and carbon stable isotopes as well as major- and trace elements in cherts and siliceous sedimentary rocks that were deposited in shallow water around the Precambrian-Cambrian transition. We investigated three lithosections in the Malyi Karatau Range in southern Kazakhstan. The lowermost chert samples of these sections are typically characterized by comparably low δ 30Si values and exhibit molds of siliceous sponge spicules. Upsection the occurrence of cross-bedding structures and granular phosphorites document the shallowing of the depositional environment, where overall increasing δ 30Si values and increasing Al/Si indicate less settlement of sponges and higher suspended particle loads. Corresponding carbon isotope records of the carbonate fraction decrease from near-zero to negative carbon isotope values averaging −5.9‰. The δ 13C carb values overall coincide with Y/Ho, the redox indicator Ce/Ce*, and mass fractions of carbonate fluorapatite, suggesting that these ratios are predominantly controlled by the mineralization of organic matter in phosphatic sediment. The studied sections document the ecological requirements for sponge settlement and proliferation, such as the presence of a hard substrate and sufficiently low suspended particle concentrations and/or low wave energy. This work suggests that the widespread appearance of karsted surfaces around the Precambrian-Cambrian transition that were subsequently submerged during the Cambrian transgression would have created permissive habitats for sponges and large phosphate deposits. The capability of sponges to oxygenate shallow seawater and extensive phosphorous burial in epicontinental basins are thus feasible mechanisms for the seawater oxygenation around the Precambrian-Cambrian transition. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the efficacy of multiparametric magnetic resonance/transrectal ultrasound fusion (MRI/TRUS fusion) biopsy versus systematic biopsy and its association with PI-RADS v2 categories in patients with suspected prostate cancer. Materials and methods: 122 patients undergoing both MRI/TRUS fusion and systematic biopsy, with suspicion of prostate cancer, with suspicious findings on MRI based on PI-RADS v2, were included between April 2016 and March 2017. Comparison of tumor detection rates using each technique and combined techniques was performed for all lesions as well as those that are traditionally difficult to access (i.e., anterior lesions). Results: Prostate cancer was detected in 83/122 patients (68%) with 74.6% clinically significant lesions (Gleason 3 + 4 or greater). There was a statistically significant difference in presence of clinically significant prostate cancer in PI-RADS v2 categories of 3, 4, and 5 (20%, 52% and 77%, respectively, p < 0.001). Fusion biopsy was positive in a significantly higher percentage of patients versus systematic biopsy (56% versus 48%, respectively, p < 0.05). The fusion biopsy alone was positive in 20%. Of 34 patients with anterior lesions on MRI, 44% were detected only by fusion biopsy, with a joint yield of 71%. In patients with previous negative systematic biopsies, 48.7% lesions were found by fusion biopsy with 20.5% being exclusively positive by this method. The percentage of positive cores for fusion biopsies was significantly higher than for systematic biopsies (26% vs. 12.3%, p < 0.001). Conclusion: The incorporation of MRI/TRUS fusion biopsy significantly improves the detection rate of prostate cancer versus systematic biopsy, particularly for anterior lesions. [ABSTRACT FROM AUTHOR]

Depositing a film via chemical vapor deposition results in superior conformity compared with other deposition techniques, primarily due to the unique chemical interactions between the surface and the reactive compounds. This technique requires a readily accessible surface and so, if the transport of the reactive species is impeded, irrespective of whether this depletion is caused by diffusion or convective flow, a homogeneous layer thickness cannot be achieved. This is often the case when applying films to the interiors of tubes, especially tubes with a dead-end, such that the inevitable loss of film-building components leads to a drop in thickness along the deposition length. The present work examined the deposition of the organic polymer poly-p-xylylene, using a reactor with dimensions that were large compared with the mean free path and tubes in which this factor (the Knudsen number) becomes unity, such that the deposition can be approximately described with the continuum model. A so-called temperature seesaw was employed to mitigate variations in layer thickness by generating an opposing temperature gradient. It was found that, under a vacuum of several tens of mTorr, the polymer could be deposited on the interior wall of a tube with an aspect ratio of at least 100 with an accuracy of ±7.5 %. The true ceiling temperature for the N derivate of this polymer was also determined to be 70 ± 2 °C. [ABSTRACT FROM AUTHOR]

Tourmaline is a common accessory mineral in the metasedimentary Pfitsch Formation located in the Pfitscher Joch (Passo de Vizze) area in the Tauern Window of the Eastern Alps. These post-Variscan metasedimentary units experienced peak metamorphic conditions of ~ 550 °C, 1.0 GPa during the Alpine orogeny. Tourmaline is most abundant in a ~ 25 m thick unit of feldspathic gneiss (~ 20–200 μg/g B), where it occurs as idiomorphic crystals typically 10 mm in length. The abundance and size of the tourmaline crystals increase near coarse-grained quartzofeldspathic segregations (~ 1200 μg/g B), reflecting the mobilization and concentration of B by metamorphic fluids. Near segregations, individual tourmaline crystals have up to three growth zones, recording pro- (~ 350–500 °C, 0.7–1.0 GPa) and retrograde (~ 400 °C, 0.2 GPa) growth as determined by combining textural information and sector-zoning thermometry. Retrograde tourmaline occurs as individual crystals as well as overgrowths on prograde tourmaline crystals, especially on the surface of extensional fractures formed by E–W extension during regional decompression. Tourmaline in the Pfitsch Formation is dravitic with a variable Fe content that correlates with the Fe content of its respective host unit. Charge balance calculations suggest that a significant proportion of Fe in tourmaline is ferric, supporting the interpretation of a subaerial continental sedimentary protolith. Tourmaline near segregations has the highest inferred ferric iron content, which decreases across growth zones, potentially reflecting a reduction of the fluid during metamorphism. The Mg/(Mg + Fe) ratio increases with prograde tourmaline growth and decreases in retrograde overgrowths. In contrast, the Ca/(Ca + Na) ratio increases gradually from 0.05 to 0.20 with prograde growth and continues to increase up to 0.25 in the retrograde overgrowths, recording the maximum Ca/(Ca + Na) ratio of the fluid during Alpine metamorphism. The metasediments of the Pfitsch Formation have very low and variable whole-rock δ 11 B values (− 14.1 to − 33.6‰), with the highest values (− 17.7 to − 14.1‰) found in B-rich samples (165–1200 μg/g B) containing abundant tourmaline, and the lowest values (− 24.2 to − 33.6‰) in B-depleted samples (21–40 μg/g), which lack tourmaline. This observation supports preferential loss of 11 B from the rocks during prograde metamorphism. Zoned tourmaline crystals in the Pfitsch formation show successively decreasing B isotope ratios from − 7.8 to − 11.2‰ in their cores and − 17.3 to − 20.3‰ in their rims. As supported by a Rayleigh fractionation model, the B-isotope values of the host rocks and the tourmaline crystals are most easily explained by the internal redistribution of B from a B-rich precursor mineral (e.g. mica) to the tourmaline during Alpine metamorphism. [ABSTRACT FROM AUTHOR]

The article addresses the influence of an aerobic exercise program combined with relaxation on pain and psychological variables in migraine patients. A controlled, randomized design was used with the intervention group receiving a treatment program of exercise combined with progressive muscle relaxation. The program led to a significant reduction of self-rated migraine pain intensity. It mentions that although there was an improvement in depression-related symptoms within the aerobic exercise group, no significant differences in psychological variables between groups were found.

Ca-Na partitioning between tourmaline and a coexisting fluid is investigated in the system CaO-NaO-BO-AlO-MgO-SiO-HO-Cl between 0.2-4.0 GPa and 500-700 °C. The synthesis experiments produced a mineral assemblage of tourmaline, coesite/quartz, and in some cases additional phases, typically comprising <1 wt% of the solid product. The synthesized tourmalines are solid solutions of dravite [NaMgAlSiO(BO)(OH)(OH)], 'oxy-uvite' (i.e. 'Ca-Mg-O root name') [CaMgAlSiO(BO)(OH)O], and magnesio-foitite [☐(MgAl)AlSiO(BO)(OH)(OH)]. Starting materials comprised a fluid of constant ionic strength (2.00 m) and an oxide mixture with a constant Mg/Al ratio. As a result, the number of vacancies at the X site and the Mg/Al ratio of tourmaline crystals synthesized at the same temperature vary only slightly. The major solid solution is Ca-Na exchange at the X site via the exchange vector CaO[Na(OH)], with the exchange vector (Ca☐)[Na] serving as a secondary Ca-incorporation mechanism. Tourmaline's X-site composition reflects the fluid composition, whereby the Ca (or Na) concentration in the fluid corresponds with the Ca (or Na) content in tourmaline at each pressure and temperature. At 0.2 GPa, 700 °C, Ca preferentially partitions into tourmaline, producing the most Ca-rich tourmaline crystals synthesized here. At pressures >1.0 GPa, Ca partitions preferentially into the fluid, resulting in Na-dominant tourmaline compositions. Temperature has a secondary effect on Ca-Na partitioning, with higher temperatures correlating with increased Ca incorporation in tourmaline. Based on the experimental findings, tourmaline is expected to have Ca-rich compositions when it forms in low pressure, high-temperature Ca-rich rocks, consistent with the current record of tourmaline occurrence. The bulk Mg/Al ratio and the pH of the tourmaline-forming system may also affect Ca incorporation in tourmaline, but remain to be investigated experimentally. [ABSTRACT FROM AUTHOR]

Olenitic tourmaline with high amounts of tetrahedral B (up to 2.53 [4]B pfu) has been synthesized in a piston-cylinder press at 4.0 GPa, 700 °C, and a run duration of 9 days. Crystals are large enough (up to 30 × 150 μm) to allow for reliable and spatially resolved quantification of B by electron microprobe analysis (EMPA), single-crystal X‑ray diffraction, and polarized single-crystal Raman spectroscopy. Tourmalines with radial acicular habit are zoned in [4]B-concentration [core: 2.53(25) [4]B pfu; rim: 1.43(15) [4]B pfu], whereas columnar crystals are chemically homogeneous [1.18(15) [4]B pfu]. An amount of 1.4(1) [4]B pfu was found in the columnar tourmaline by single-crystal structure refinement (SREF) (R = 1.94%). The EMPA identify [T]Si–1 [V,W]O–1 [T]B1 [V,W](OH)1 as the main and [X]...–1 [T]Si–1 [X]Na1 [T]B1 as minor exchange vectors for [4]B-incorporation, which is supported by the SREF. Due to the restricted and well-defined variations in chemistry, Raman bands in the OH-stretching region (3000–3800 cm–1) are unambiguously assigned to a specific cation arrangement. We found the sum of the relative integrated intensity (Irel) of two low-frequency bands at 3284–3301 cm–1 (ν1) and 3367–3390 cm–1 (ν2) to positively correlate with the [4]B concentrations: [4]B [pfu] = 0.03(1) × [Irel (ν1) + Irel (ν2)]. Hence, those bands correspond to configurations with mixed Si/B occupancy at the T site. Our semi-quantitative correlation also holds for well-characterized natural [4]B-bearing tourmaline from the Koralpe, Austria. This work shows the potential for Raman spectroscopy as a non-destructive method for the chemical classification of (precious) natural tourmaline, and as a tool to rapidly characterize chemical zonation of tourmalines in thin section. [ABSTRACT FROM AUTHOR]

We performed hydration experiments of pure and Nb-, Cr-, and V-doped synthetic dry (H2O < 3 ppm) single rutile crystals. They were equilibrated with pure H2O in hydrothermal experiments at constant conditions of 600 °C, 400 MPa, and fO2 near the Ni-NiO buffer, run time between ~25 min and 14 days. Slabs cut parallel to (110) of the reacted single crystals (1 to 2 mm³) were analyzed for H+ by FTIR. Hydration occurs almost spontaneously and the H2O-equivalent is uniformly distributed in the samples, but depends extremely on trace element contents. In pure rutile, the average H2O-content is 314 ± 50 ppm, the saturation level at these conditions. Rutile doped with 500 ppm Nb has a lower average H2O content of ~235 ppm, rutile with 2000 ppm Cr has ~900 ppm H2O, and rutile with 2000 ppm V does not incorporate H2O. During stepwise heating at atmospheric pressure of a reacted Nb-doped rutile, H+ is quickly released between 450 and 550 °C. UV-VIS spectra of unreacted colorless and reacted deep blue pure rutile show the rutile-characteristic sharp absorption edge in the UV spectra. The reacted rutile has a broad absorption band at 6500 cm-1 wavenumber attributed to intervalence charge transfer transition Ti3++Ti4+ → Ti4++Ti3+. The reduction of Ti4+ to Ti3+ is charge balanced by the incorporation of H+. The Nb-doped rutile changed its color from light greenish-blue (untreated) to deep blue. In the untreated Nb rutile, the UV-VIS absorption band at 6500 cm-1 indicates that Nb5+ is charge balanced by Ti3+. In the reacted Nb-rutile the absorption band is more intense, but compared with the pure rutile, H+ incorporation is lower by the equivalent of Ti3+ reduced in the untreated rutile. Reacted Cr-rutile almost retains its brownish-orange color, but the spectrum shows a prominent Ti3+/Ti4+ IVCT band at ~6400 cm-1 with moderate intensity considering the high-H2O contents of ~900 ppm. The high-H+ contents are best explained by the reduction of Cr4+ to Cr2+. The UV-VIS spectra of the dark-blue to opaque V-doped rutile show a very strong absorption toward low energies, which is likely caused by reduction of Ti4+ to Ti3+ for charge balance of V5+. This forms a deep narrow window of transmittance in the range 25 000--20 000 cm-1, which causes the dark-blue color. To explore the possible use of H-in-rutile as a geohygrometer, geothermobarometer, and oxybarometer, we measured the H+ content in a natural rutile crystal from a retrograded eclogite with a zoned trace element (Fe, Nb, and Zr) content. The crystal reveals a slight correlation between the variable H2O (~200 to 900 ppm) and its trace element concentrations. The observations indicate that the preservation of H+ contents in this natural rutile is a complicated interplay of diffusive reequlibration of fast H+, slower Fe and very slow other trace elements. An interpretation of the H2O contents of the natural crystal in terms of fO2 or aH2O is not possible. [ABSTRACT FROM AUTHOR]

Interfacial tension between immiscible liquids is an important thermodynamic parameter of silicate melt unmixing and a property that determines the kinetics of phase separation. In this study, we present experimental measurements of interfacial tension between immiscible Fe-rich and silica-rich melts in the system K2O-FeO-Fe2O3-Al2O3-SiO2. We have also measured densities and surface tensions of the individual immiscible liquid phases. The measurements were carried out in air at 1500-1550 °C by the maximum detachment force method employing vertical cylinder geometry and using a gravimetric balance system. We have chosen the most oxidized and contrasting liquid compositions containing 73 and 17 wt% SiO2 and 14 and 80 wt% FeOt, respectively, that have been shown to coexist in air at and above 1465 °C. Interfacial tension between the synthetic immiscible liquids decreases with increasing temperature from 16.4 ± 3.1 mN/m at 1500 °C to 7.8 ± 1.1 mN/m at 1550 °C. Interfacial tension between natural, less compositionally contrasting ferrobasaltic and rhyolitic melts should be even lower by a factor of 2 or 3. Very low interfacial tension implies easy nucleation of immiscible liquid droplets and very slow coarsening of resulting silicate emulsions. [ABSTRACT FROM AUTHOR]

Titanite growth at the expense of rutile during retrograde hydration of eclogite into amphibolite is a common phenomenon. We investigated an amphibolite sample from the Tromsø eclogite facies terrain in Northern Norway to gain insight into the trace element distribution between rutile and titanite during incomplete resorption of the rutile by titanite. Patchy compositional zoning of Al, Ti, and F in titanite relates to the presence of a fluid with variable Ti/Al and/or F during its growth. Laser ablation ICP–MS and electron microprobe data for high field strength elements (HFSE: Nb, Zr, Ta, and Hf) of rutile resorbed by titanite indicate a pronounced enrichment of these elements in the rim of a large single rutile crystal (~8 mm) and a systematic decrease towards uniform HFSE contents in the large core. HFSE contents of smaller rutile grains (~0.5 mm) and rutile inclusions (<100 μm) in the titanite overgrowth are similar or higher than in the rims of large rutile crystals. Element profiles from the rim inward demonstrate that HFSE enrichment in rutile is controlled by diffusion. HFSE ratios in diffusion-altered rutile show systematic variations compared with the uniform core composition of the large rutile. Modelling of Zr and Nb diffusion in rutile indicates that diffusion coefficients in rutile in fluid-dominated natural systems must be considerably higher than those determined experimentally at 1 bar in dry systems. Variations of HFSE contents in the newly formed titanite show no systematic spatial distribution. HFSE ratios in titanite and the rims of rutile are different, indicating different solid/fluid distribution coefficients in these minerals. Element fractionation by diffusion into the relict rutile and during fluid-mediated growth of new titanite could substantially change the HFSE budget of these minerals and could affect their use for geochemical tracing and other applications, such as Zr-based geothermobarometry. [ABSTRACT FROM AUTHOR]

Although orthopyroxene (Opx) is present during a wide range of magmatic differentiation processes in the terrestrial and lunar mantle, its effect on melt trace element contents is not well quantified. We present results of a combined experimental and computational study of trace element partitioning between Opx and anhydrous silicate melts. Experiments were performed in air at atmospheric pressure and temperatures ranging from 1,326 to 1,420°C in the system CaO–MgO–Al2O3–SiO2 and subsystem CaO–MgO–SiO2. We provide experimental partition coefficients for a wide range of trace elements (large ion lithophile: Li, Be, B, K, Rb, Sr, Cs, Ba, Th, U; rare earth elements, REE: La, Ce, Nd, Sm, Y, Yb, Lu; high field strength: Zr, Nb, Hf, Ta, Ti; transition metals: Sc, V, Cr, Co) for use in petrogenetic modelling. REE partition coefficients increase from $$ D_{\text{La}}^{{\text{Opx}} {\hbox{-}} {\text{melt}}} \sim 0.0005 $$ to $$ D_{\text{Lu}}^{{{\text{Opx}} {\hbox{-}} {\text{melt}}}} \sim 0.109 $$, D values for highly charged elements vary from $$ D_{\text{Th}}^{{{\text{Opx}} {\hbox{-}} {\text{melt}}}} \sim 0.0026 $$ through $$ D_{\text{Nb}}^{{{\text{Opx}} {\hbox{-}} {\text{melt}}}} \sim 0.0033 $$ and $$ D_{\text{U}}^{{{\text{Opx}} {\hbox{-}} {\text{melt}}}} \sim 0.0066 $$ to $$ D_{\text{Ti}}^{{\text{Opx}} {\hbox{-}} {\text{melt}}} \sim 0.058 $$, and are all virtually independent of temperature. Cr and Co are the only compatible trace elements at the studied conditions. To elucidate charge-balancing mechanisms for incorporation of REE into Opx and to assess the possible influence of Fe on Opx-melt partitioning, we compare our experimental results with computer simulations. In these simulations, we examine major and minor trace element incorporation into the end-members enstatite (Mg2Si2O6) and ferrosilite (Fe2Si2O6). Calculated solution energies show that R2+ cations are more soluble in Opx than R3+ cations of similar size, consistent with experimental partitioning data. In addition, simulations show charge balancing of R3+ cations by coupled substitution with Li+ on the M1 site that is energetically favoured over coupled substitution involving Al–Si exchange on the tetrahedrally coordinated site. We derived best-fit values for ideal ionic radii r0, maximum partition coefficients D0, and apparent Young’s moduli E for substitutions onto the Opx M1 and M2 sites. Experimental r0 values for R3+ substitutions are 0.66–0.67 Å for M1 and 0.82–0.87 Å for M2. Simulations for enstatite result in r0 = 0.71–0.73 Å for M1 and ~0.79–0.87 Å for M2. Ferrosilite r0 values are systematically larger by ~0.05 Å for both M1 and M2. The latter is opposite to experimental literature data, which appear to show a slight decrease in $$ r_{0}^{{{\text{M}}2}} $$ in the presence of Fe. Additional systematic studies in Fe-bearing systems are required to resolve this inconsistency and to develop predictive Opx-melt partitioning models for use in terrestrial and lunar magmatic differentiation models. [ABSTRACT FROM AUTHOR]

The Jurassic to Early Cretaceous magmatic arc of the Andes in northern Chile was a site of major additions of juvenile magmas from the subarc mantle to the continental crust. The combined effect of extension and a near stationary position of the Jurassic to lower Cretaceous arc favoured the emplacement and preservation of juvenile magmatic rocks on a large vertical and horizontal scale. Chemical and Sr, Nd, and Pb isotopic compositions of mainly mafic to intermediate volcanic and intrusive rock units coherently indicate the generation of the magmas in a subduction regime and the dominance of a depleted subarc mantle source over contributions of the ambient Palaeozoic crust. The isotopic composition of the Jurassic (206Pb/204Pb: ∼ 18.2; 207Pb/204Pb: ∼ 15.55; 143Nd/144Nd: ∼ 0.51277; 87Sr/86Sr: ∼ 0.703–0.704) and Present (206Pb/204Pb: ∼ 18.5; 207Pb/204Pb: ∼ 15.57; 143Nd/144Nd: ∼ 0.51288; 87Sr/86Sr: ∼ 0.703–0.704) depleted subarc mantle beneath the Central and Southern Andes (18°–40°S) was likely uniform over the entire region. Small differences of isotope ratios between Jurassic and Cenozoic to Recent of subarc mantle-derived could be explained by radiogenic growth in a still uniform mantle source. [ABSTRACT FROM AUTHOR]