Characterization of an early metamorphic stage through inclusions in zircon of a diamondiferous quartzofeldspathic rock from the Erzgebirge, Germany

About 1000 zircon grains from a diamondiferous quartzofeldspathic rock of the Saxonian Erzgebirge were investigated for inclusions using optical microscopy and confocal laser-Raman spectroscopy. Cathodoluminescence imagery was applied to characterize the growth zone of zircon where the inclusions occurred. The most abundant inclusion minerals are microdiamonds. Coesite was not detected. However, garnet and jadeite occur as rare inclusions in zircon cores where diamonds are lacking. Jadeite was detected for the first time in quartzofeldspathic rocks from the crystalline complex of the Erzgebirge. The compositions of the pristine garnets in the zircons are similar to those of core areas of mi…

Radiation damage in zircon

A single, zoned, Sri Lankan zircon exhibits a range of microstructures from crystalline to nearly amorphous that are the result of radiation damage over a dose range of 2.1–10.1·1015 α-decay events/mg (0.16–0.47 dpa). The zones in the crystal were examined at a variety of length scales using optical microscopy, micro-Raman spectroscopy, electron microprobe analysis, and transmission electron microscopy. Birefringence varies linearly with dose: birefringence = −4.71·10−18 /g· D α + 4.86·10−2. Full width at half maximum (FWHM) measurements of the B1g(ν3) peak, as determined by micro-Raman spectroscopy, were used to estimate the extent of radiation damage in each zone. The radiation dose (calc…

Zircon M257 - a homogeneous natural reference material for the ion microprobe U-Pb analysis of zircon

We introduce and propose zircon M257 as a future reference material for the determination of zircon U-Pb ages by means of secondary ion mass spectrometry. This light brownish, flawless, cut gemstone specimen from Sri Lanka weighed 5.14 g (25.7 carats). Zircon M257 has TIMS-determined, mean isotopic ratios (2s uncertainties) of 0.09100 ± 0.00003 for 206pb/238U and 0.7392 ± 0.0003 for 207pb/235U. Its 206pb/238U age is 561.3 ± 0.3 Ma (unweighted mean, uncertainty quoted at the 95% confidence level); the U-Pb system is concordant within uncertainty of decay constants. Zircon M257 contains ∼ 840 μg g−1 U (Th/U ∼ 0.27). The material exhibits remarkably low heterogeneity, with a virtual absence of…

Decrespignyite-(Y), a new copper yttrium rare earth carbonate chloride hydrate from Paratoo, South Australia

AbstractDecrespignyite-(Y) is a new copper yttrium rare earth carbonate chloride hydrate from the Paratoo copper mine, near Yunta, Olary district, South Australia. Decrespignyite-(Y) occurs as blue crusts, coatings and fillings in thin fissures on the slatey country rock. Individual pseudohexagonal platelets are typically 10–50 µm in maximum dimension and are often curved. Associated minerals include caysichite-(Y), donnayite-(Y), malachite and kamphaugite-(Y). Electron microprobe and CHN analyses gave: Y2O3 42.2; La2O3 0.1; Pr2O3 0.1; Nd2O3 1.3; Sm2O3 1.0; Gd2O3 4; Tb2O3 0.4; Dy2O3 3.7; Ho2O3 2.6; Er2O3 2.5; CaO 0.5; CuO 10.9; Cl 3.0; CO2 19.8; H2O 10.8, yielding an empirical formula of (Y…

Evidence for fractional condensation and reprocessing at high temperatures in CH chondrites

We performed a detailed study of silica-rich components (SRC) in the paired CH chondrites Acfer 182 and 207. These SRCs appear either as chondrules or fragments, and they contribute <0.1 vol% to the bulk meteorite. They usually contain a silica and a silicate portion. Both portions are, in most cases, cryptocrystalline and have bulk SiO2-concentrations between 65 and 85 wt%. The silicate generally has a pyroxene normative composition. The silica often appears as blebs within the silicate matrix or vice versa. If there are no blebs, silica and silicate still form rounded interfaces. The SRCs are depleted in refractory elements like Ca, Al, and Ti relative to CI. A few SRC- like objects are e…

Zircon M127 - A Homogeneous Reference Material for SIMS U-Pb Geochronology Combined with Hafnium, Oxygen and, Potentially, Lithium Isotope Analysis

Faculty of Geosciences, Geography and Astronomy, University of Vienna; Beijing SHRIMP Centre, Chinese Academy of Geological Sciences; European Commission [MEXC-CT-2005-024878]; FWF Austrian Science Fund [P20028-N10, P24448-N19]; U.S. National Science Foundation [EAR 1524336]

PETTERDITE, THE Cr-DOMINANT ANALOGUE OF DUNDASITE, A NEW MINERAL SPECIES FROM DUNDAS, TASMANIA, AUSTRALIA AND CALLENBERG, SAXONY, GERMANY

Petterdite is a newly discovered hydrated lead chromium hydroxyl carbonate, the Cr 3+ -dominant analogue of dundasite, with a formula PbCr 2 (CO 3 ) 2 (OH) 4 ·H 2 O. The type locality is the Red Lead mine, on the Zeehan–Dundas mining field in northwestern Tasmania, Australia. The mineral also occurs in small amounts at the Callenberg nickel deposit, Saxony, Germany. Petterdite forms thin crusts made up of tiny platy crystals up to about 15 μm across, associated with crocoite and anglesite at the type locality, and with crocoite, cerussite, bindheimite, pyromorphite, and relict galena at Callenberg. The petterdite crusts are pale greyish to pinkish violet and non-fluorescent; they have an ea…

Resorption, growth, solid state recrystallisation, and annealing of granulite facies zircon—a case study from the Central Erzgebirge, Bohemian Massif

Zircon crystals have been investigated from a gneiss area in the Central Erzgebirge, Bohemian Massif, where small occurrences/lenses of granulites (and sometimes eclogites) are located within amphibolite facies gneisses. Geological relationships indicate that leucocratic quartzofeldspathic rocks within the granulite boudins represent melts, whereas garnet-rich melanocratic rocks are considered restites, derived through multiple extraction of the leucocratic melts. The morphology of zircon crystals is quite different in these two types of granulites, with rounding pointing to higher zircon resorption in garnet-rich rocks due to multiple interaction with melts. Extensive new zircon growth can…

Partial high-pressure aragonitization of micritic limestones in an accretionary complex, Tavşanlı Zone, NW Turkey

Pelagic micritic limestones within an upper Cretaceous accretionary complex in the Tavsanli Zone, NW Turkey, preserve textures indicating incomplete prograde transformation of micritic calcite to aragonite, representing the only known example of this type. Aragonitization starts at the central parts of the micritic limestone beds and advances towards the lower and upper parts of the layers at the expense of micrite. Micrite is very fine grained (<0.003 mm) and contains radiolaria, foraminifera and thin shell fragments. Aragonite forms large crystals, up to 3 cm across, with straight grain boundaries and c-axis mostly subparallel to the carbonate beds. Relict micritic portions are devoid of …

Raman Mapping Applied to Reveal Internal Structures of Natural Minerals

Incomplete retention of radiation damage in zircon from Sri Lanka

A suite of 18 zircon gemstones from placers in the Highland/Southwestern Complex, Sri Lanka, were subjected to a comprehensive study of their radiation damages and ages. The investigation included X-ray diffraction, Raman and PL spectroscopy, electron microprobe, PIXE and HRTEM analysis, as well as (U-Th)/He and SHRIMP U-Th-Pb age determinations. Zircon samples described in this study are virtually homogeneous. They cover the range from slightly metamict to nearly amorphous. Generally concordant U-Th-Pb ages averaging 555 ± 11 Ma were obtained. Late Ordovician zircon (U-Th)/He ages scattering around 443 ± 9 Ma correspond reasonably well with previously determined biotite Rb-Sr ages for rock…

ChemInform Abstract: Facile Synthesis and Characterization of Monocrystalline Cubic ZrO2Nanoparticles.

Abstract Crystalline ZrO2 nanoparticles were prepared from zirconium isopropoxide by slow hydrolysis and subsequent hydrothermal treatment of solutions containing various amounts of sodium hydroxide at 180 °C. Whereas moderately basic solutions lead to the formation of nanoparticles of monoclinic ZrO2 with plate-like morphology, and nanoparticles of the cubic ZrO2 high-temperature polymorph with diameters of approx. 5 nm were obtained from strongly basic solutions. The morphology, structure and properties of as-synthesized nanoparticles were characterized using HRTEM, XRD, Raman spectroscopy, UV–vis, PL spectroscopy and BET measurements. The formation of both, the monoclinic and the cubic p…

15. Spectroscopic methods applied to zircon

Natural and synthetic (pure and doped) zircon (ZrSiO4) have been studied with a variety of spectroscopic techniques. These techniques are based on different physical phenomena, for instance transitions between spin states of nuclei and electrons, energetic transitions of valence electrons, intra-molecular vibrations, or vibrations of atoms and molecular units in the lattice. All of the diverse spectroscopic techniques, however, have in common that they probe energy differences between a ground and excited states, mostly upon interaction of the mineral with incident radiation. Such interactions are not only determined by the excited elementary particles or molecules themselves but depend gre…

Spectroscopic methods applied to zircon

Natural and synthetic (pure and doped) zircon (ZrSiO4) have been studied with a variety of spectroscopic techniques. These techniques are based on different physical phenomena, for instance transitions between spin states of nuclei and electrons, energetic transitions of valence electrons, intra-molecular vibrations, or vibrations of atoms and molecular units in the lattice. All of the diverse spectroscopic techniques, however, have in common that they probe energy differences between a ground and excited states, mostly upon interaction of the mineral with incident radiation. Such interactions are not only determined by the excited elementary particles or molecules themselves but depend gre…

Effects of natural radiation damage on back-scattered electron images of single crystals of minerals

Generally, it has been assumed that signal intensity variations in back-scattered electron (BSE) images of minerals are mainly controlled by chemical heterogeneity. This is especially true for images of single crystals, where effects of different crystal orientations with respect to the incident beam on the observed BSE are excluded. In contrast, we show that local variations of the structural state within single-crystals (i.e., degree of lattice order or lattice imperfectness) may also have dramatic effects on the back-scattering of electrons. As an example, we present BSE images of single-crystals of natural zircon, ZrSiO 4 , whose intensity patterns are predominantly controlled by struct…

The nature of radiohaloes in biotite: Experimental studies and modeling

Several micro-techniques (confocal laser-Raman microprobe, optical absorption micro-spectroscopy, high-resolution transmission electron microscopy, electron microprobe analysis) were employed in the detailed characterization of radiohaloes in biotites from two Variscan rocks from Germany. The studied biotites are intermediate members of the phlogopite-annite series with Mg/Fe 2+ ratios in the range 1.6–1.0. Radiohaloes in biotite resulted from the impact of 4 He cores (α-particles) emitted from actinide-bearing inclusions. Monte Carlo simulations yielded α ( 238 U, 235 U, and 232 Th series) penetration ranges in biotite between 12.5 and 37.3 μm, which are in reasonable agreement with the ob…

Zircon ages of high-grade gneisses in the Eastern Erzgebirge (Central European Variscides)—constraints on origin of the rocks and Precambrian to Ordovician magmatic events in the Variscan foldbelt

Abstract This study is an attempt to unravel the tectono-metamorphic history of high-grade metamorphic rocks in the Eastern Erzgebirge region. Metamorphism has strongly disturbed the primary petrological genetic characteristics of the rocks. We compare geological, geochemical, and petrological data, and zircon populations as well as isotope and geochronological data for the major gneiss units of the Eastern Erzgebirge; (1) coarse- to medium-grained “Inner Grey Gneiss”, (2) fine-grained “Outer Grey Gneiss”, and (3) “Red Gneiss”. The Inner and Outer Grey Gneiss units (MP–MT overprinted) have very similar geochemical and mineralogical compositions, but they contain different zircon populations…

Growth of zircon and titanite during metamorphism in the granitoid-gneiss terrane south of the Barberton greenstone belt, South Africa

AbstractSHRIMP U-Pb zircon and titanite dating have been used to constrain the timing of mid- to lower- crustal metamorphism (∼650—700°C and 8—11 kbar) and syn-kinematic melting in the granitoid gneiss- dominated terrane south of the Barberton greenstone belt, South Africa. This study is concentrated on a clastic metasedimentary unit exposed in one of several greenstone remnants and a late-kinematic trondhjemite intrusive into spatially associated mixed gneisses. Locally, the clastic metasediments show extensive replacement of garnet and plagioclase by epidote and titanite. The titanites yield an upper intercept date of 3229±9 Ma, and provide a minimum age for the peak of metamorphism. Zirc…

In situ micro-Raman and X-ray diffraction study of diamonds and petrology of the new ureilite UAE 001 from the United Arab Emirates

International audience; A new olivine-pigeonite ureilite containing abundant diamonds and graphite was found in the United Arab Emirates. This is the first report of a meteorite in this country. The sample is heavily altered, of medium shock level, and has a total weight of 155 g. Bulk rock, olivine (Fo79.8-81.8) and pyroxene (En73.9-75.2, Fs15.5-16.9, Wo8.8-9.5) compositions are typical of ureilites. Olivine rims are reduced with Fo increasing up to Fo96.1-96.8. Metal in these rims is completely altered to Fehydroxide during terrestrial weathering. We studied diamond and graphite using micro-Raman and in situ synchrotron X-ray diffraction. The main diamond Raman band (LO=TO mode at ~1332 c…

Growth zoning and strain patterns inside diamond crystals as revealed by Raman maps

The Raman mapping technique provides a non-destructive means of studying internal growth textures and other micro-structural heterogeneity inside diamond single-crystals. Raman maps showing distribution patterns of the bandwidth (FWHM) of the main first-order lattice vibration of diamond ( LO=TO phonon at ~1332 cm −1 ) along two-dimensional planes inside diamond crystals may reveal the internal growth zoning of these crystals. The observed zoning is affected, and in some cases even obscured in micro-areas adjacent to inclusions, by patterns of heterogeneous strain in the diamond. We present Raman maps obtained from diamond crystals containing large, single-crystal graphite inclusions, from …

Detection of a Ca-rich lithology in the Earth's deep (&gt;300 km) convecting mantle

Earth's deep convecting upper mantle is believed to represent a rather homogenous geochemical reservoir of spinel or garnet lherzolite with primitive major element and moderately depleted trace element composition. Only where subduction occurs is this homogeneity disrupted by a suite of rocks ranging from eclogites/garnet pyroxenites (former oceanic crust) to residual harzburgites. In addition to these well documented peridotitic and metabasaltic rocks we have now discovered the presence of a chemically distinct reservoir in the deep convecting upper mantle. In situ structural analyses (micro X-ray diffraction and micro Raman spectroscopy) and three-dimensional trace element mapping (confoc…

Internal structures and dating of complex zircons from Meissen Massif monzonites, Saxony

Abstract U–Pb zircon ages were determined for accessory zircons from two monzonites from the Meissen Massif (Northern Bohemian Massif, Germany) by SHRIMP ion microprobe. BSE and CL imaging revealed that the monzonite zircons, showing oscillatory growth zoning, often contain inherited cores. Raman microprobe measurements showed that zoned rims (U 277–1426 ppm, Th 144–910 ppm) are slightly disordered to moderately metamict whereas cores have a wide spectrum of structural states, from well-crystallized to highly metamict. The radionuclide (U+Th) content of cores varies from a few hundred to more than 20,000 ppm. SHRIMP ion probe measurements on zoned rims, interpreted as zircon growth during c…

Spectroscopic 2D-tomography: Residual pressure and strain around mineral inclusions in diamonds

We have studied high-pressure inclusions (Ca-silicates, coesite, graphite) in three large diamonds, one from the Kankan district, Guinea, and the other two from the Panda kimberlite, Ekati diamond mines, Canada. Using the in situ point-by-point mapping technique with a confocal Raman system, the mineralogy of the inclusions, as well as their area distribution pattern ( e.g. , of different Ca-silicate phases) and their order-disorder distribution pattern (shown for graphite/disordered carbon), were determined. Raman mapping of the host diamonds yielded 2D-tomographic pressure and strain distribution patterns and provided information on the residual pressure of the inclusions (∼ 2.3 GPa for a…

An XRD, TEM and Raman study of experimentally annealed natural monazite

The healing of radiation damage in natural monazite has been experimentally studied in annealing experiments using XRD, TEM, Raman microprobe and cathodoluminescence analysis. The starting material was a chemically homogeneous monazite from a Brazilian pegmatite with a concordant U–Pb age of 474 ± 1 Ma and a U–Th/He age of 479 Ma. The monazite shows nm-scale defects induced by radioactive decay. The Xray pattern of the unheated starting material revealed two distinct monazite ''phases'' A and B with slightly different lattice parameters. Monazite A shows sharp reflections of high amplitudes and slightly expanded lattice parameters (1% in volume) compared to a standard monazite. Phase B exhi…

Crystallization of Vaterite Nanowires by the Cooperative Interaction of Tailor-Made Nucleation Surfaces and Polyelectrolytes

The concepts of template-induced crystallization on self-assembled monolayers (SAMs) and the use of polymer additives are combined into a new strategy, where, through the cooperative interaction of a SAM matrix involved in the nucleation process, poly(acrylic acid), a dissolved polyelectrolyte, and the dissolved ions, hierarchically ordered mineral structures are formed. The adsorption of poly(acrylic acid) to the SAM is monitored using a quartz microbalance. Transmission electron microscopy measurements on samples that are taken from polyacrylate solution in short intervals after the start of the reaction reveals that nanometer-sized particles pre-formed in solution are being attached to t…

Low-temperature Zr mobility: An in-situ synchrotron-radiation XRF study of the effect of radiation damage in zircon on the element release in $H_{2}O+HCl\pm SiO_{2}$ fluids

The release of Zr, U, and Pb from nearly metamict zircon and its recrystallized analog and of Zr from fully crystalline and slightly radiation-damaged zircon in H 2 O + HCl ± SiO 2 fluids was investigated in situ at temperatures between 200 and 500 °C using a hydrothermal diamond-anvil cell and time-resolved synchrotron-radiation XRF analyses. Dissolution of nearly metamict zircon proceeded much faster than that of zircon with little or no radiation damage and resulted in a 1.5 to 2 log units higher Zr molality in 6 to 7 m HCl fluids. Extensive recrystallization of the almost fully amorphous material started at 260 to 300 °C in H 2 O + HCl, and at about 360 °C if quartz was added, and was c…

Morphosynthesis of Strontianite Nanowires Using Polyacrylate Templates Tethered onto Self-Assembled Monolayers

Strontianite nanowires have been synthesized on self-assembled monolayers (SAM) in the presence of polyacrylate templates. The morphology of this product exhibits characteristic differences from that of products obtained in the absence of polyacrylate. It is demonstrated that the template-induced crystallization process involves the interaction between the SAM surface, polyacrylate (a dissolved polyelectrolyte), and the cations/anions in solution. By the combination of these components, hierarchically ordered mineral hybrid structures are formed.

Effects of irradiation damage on the back-scattering of electrons: silicon-implanted silicon

Radiation damage in an (initially crystalline) silicon wafer was generated by microbeam implantation with 600 keV Si+ ions (fluence 5 x 1014 ions/cm²). To produce micro-areas with different degrees of damage, 14 implantations at different temperatures (between 23 and 225 °C) were done. The structural state of irradiated areas was characterized using Raman spectroscopy and electron back-scatter diffraction. All irradiated areas showed strong structural damage in surficial regions (estimated depth <1 μm), and at implant substrate temperatures of below 130 °C, the treatment has caused complete amorphization. Back-scattered electron (BSE) images exhibited that observed BSE intensities correlate…

Long-term stability of alpha particle damage in natural zircon

Abstract We report the first discovery of radiation damage haloes generated by alpha particles in zircon. Proterozoic zircon crystals from a potassium-rich leucogranite from the Adirondack Mountains, New York State, have interior regions that are generally low in actinide elements (UO 2  + ThO 2  ≤ 0.02 wt.%) but show a remarkable pattern of heterogeneous metamictisation. The degree of radiation damage in these regions is not uniformly low, as would be expected if it corresponded to the observed actinide distribution patterns and age of the crystals. Rather, radiation damage is significantly increased in the outermost micro-areas of the low-actinide regions. The additional radiation damage …

Ronneburgite, K2MnV4O12, a new mineral from Ronneburg, Thuringia, Germany: Description and crystal structure

Ronneburgite is a new chain vanadate mineral from Ronneburg, Thuringia, Germany. It occurs as reddish-brown crystals of equant, flattened, or short prismatic habit, up to 0.5 mm in length. The crystals have an adamantine luster and are translucent. Ronneburgite is biaxial negative with refractive indices n α = 1.925(5), n β = 1.960(10), n γ = 1.988(4), and 2 V x = 82°. Electron microprobe analysis (K 2 O = 16.93, MnO = 12.44, MgO = 0.62, V 2 O 5 = 68.54; total = 98.53 wt%) gives the empirical formula K 1.91 Mn 0.93 Mg 0.08 V 4.00 O 11.96 , which simplifies to K 2 MnV 4 O 12 . Ronneburgite is mono-clinic, space group P 2 1 / n , with a = 8.183(3), b = 9.247(3), c = 8.651(2) A, and β = 109.74…

Origin of SiO2-rich components in ordinary chondrites

Abstract Silica-rich objects are common minor components in ordinary chondrites (OC), occurring as fragments and as chondrules. Their typical paragenesis is orthopyroxene + SiO 2 (with bulk SiO 2 >65 wt%) and occasionally with additional olivine and/or spinel. Individual silica-rich components (SRC) have previously been studied in various types of OCs, although there is only one comprehensive study of these objects by Brigham et al. [Brigham, C.A., Murrell, M.T., Yabuki, H., Ouyang, Z., El Goresy, A., 1986. Silica-bearing chondrules and clasts in ordinary chondrites. Geochim. Cosmochim. Acta 50, 1655–1666]. Several different explanations of how SRCs formed have been published. The main ques…

Facile synthesis and characterization of monocrystalline cubic ZrO2 nanoparticles

Abstract Crystalline ZrO2 nanoparticles were prepared from zirconium isopropoxide by slow hydrolysis and subsequent hydrothermal treatment of solutions containing various amounts of sodium hydroxide at 180 °C. Whereas moderately basic solutions lead to the formation of nanoparticles of monoclinic ZrO2 with plate-like morphology, and nanoparticles of the cubic ZrO2 high-temperature polymorph with diameters of approx. 5 nm were obtained from strongly basic solutions. The morphology, structure and properties of as-synthesized nanoparticles were characterized using HRTEM, XRD, Raman spectroscopy, UV–vis, PL spectroscopy and BET measurements. The formation of both, the monoclinic and the cubic p…

Further characterisation of the 91500 zircon crystal

This paper reports the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), secondary ion mass spectrometry (SIMS) and laser fluorination analyses. The focus of this initiative was to establish the suitability of this large single zircon crystal for calibrating in situ analyses of the rare earth elements and oxygen isotopes, as well as to provide working values for key geochemical systems. In addition to extensive testing of the chemical and structural homogeneity of this sample, the occurrence of banding in 91500 in both backscattered electron and cathodolumines…

CO2-recycling to the deep convecting mantle

Institut fur Geowissenschaften, Johann Wolfgang Goethe-Universitat Frankfurt, 60054 Frankfurt, Germany (f.brenker@ em.uni-frankfurt.de) Max Planck Institute for Chemistry, Mainz, Germany (cvollmer@mpch-mainz.mpg.de) Ghent University, Department of Analytical Chemistry, Belgium (Laszlo.Vincze@UGent.be) University of Antwerp, Department of Chemistry, Belgium (bart.vekemans@ua.ac.be; koen.janssens@ua.ac.be) Institute of Experimental Physics, University of Debrecen, Hungary (szaloki@tigris.klte.hu) Institut fur Geowissenschaften, Johannes Gutenberg-Universitat, Mainz, Germany (nasdala@uni-mainz.de) KM Diamond Exploration Ltd., Vancouver, Canada (felixvkaminsky@cs.com)