A New LA ‐ ICP ‐ MS Method for Ti in Quartz: Implications and Application to High Pressure Rutile‐Quartz Veins from the Czech Erzgebirge

Experimental determination of the pressure and temperature controls on Ti solubility in quartz provides a calibration of the Ti-in-quartz (TitaniQ) geothermometer applicable to geological conditions up to ~ 20 kbar. We present a new method for determining 48Ti mass fractions in quartz by LA-ICP-MS at the 1 μg g−1 level, relevant to quartz in HP-LT terranes. We suggest that natural quartz such as the low-CL rims of the Bishop Tuff quartz (determined by EPMA; 41 ± 2 μg g−1 Ti, 2s) is more suitable than NIST reference glasses as a reference material for low Ti mass fractions because matrix effects are limited, Ca isobaric interferences are avoided, and polyatomic interferences at mass 48 are i…

Fe-rich Dunite Xenoliths from South African Kimberlites: Cumulates from Karoo Flood Basalts

Fe-rich dunite xenoliths within the Kimberley kimberlites comprise olivine neoblasts with minor elongated, parallel-oriented ilmenite, and rarely olivine porphyroclasts and spinel. Compared with typical mantle peridotites, olivines in the Fe-rich dunites have lower forsterite (Fo87^89) and NiOcontents (1300^2800 ppm), which precludes a restitic origin for the dunites. Chrome-rich spinels are remnants of a metasomatic reaction that produced ilmenite and phlogopite.Trace element compositions differ between porphyroclastic and neoblastic olivine, the latter having higherTi, V, Cr and Ni and lower Zn, Zr and Nb contents, documenting their different origins.The dunites have high Os/Os ratios (0 …

Sr/Ca and Mg/Ca ratios of ontogenetically old, long-lived bivalve shells (Arctica islandica) and their function as paleotemperature proxies

International audience; The Sr/Ca and Mg/Ca ratios of many biogenic skeletons provide useful paleotemperature estimates. As yet however, it has remained largely impossible to obtain such information from bivalve shells. In the present study, metal-to-calcium values in the hinge plate (aragonite, outer shell layer) of four ontogenetically old (85 to 374 year-old) specimens of the long-lived bivalve, Arctica islandica, were measured on a LA-ICP-MS. The shells were collected alive in 1868, 1986 and 2003 from three different localities around Iceland. With increasing ontogenetic age and decreasing growth rate, a distinct trend toward increasing Sr/Ca (max. 5.17 mmol/mol) and Mg/Ca values (max. …

Kidney Stones in Primary Hyperoxaluria: New Lessons Learnt

To investigate potential differences in stone composition with regard to the type of Primary Hyperoxaluria (PH), and in relation to the patient’s medical therapy (treatment naïve patients versus those on preventive medication) we examined twelve kidney stones from ten PH I and six stones from four PH III patients. Unfortunately, no PH II stones were available for analysis. The study on this set of stones indicates a more diverse composition of PH stones than previously reported and a potential dynamic response of morphology and composition of calculi to treatment with crystallization inhibitors (citrate, magnesium) in PH I. Stones formed by PH I patients under treatment are more compact and…

Freshening of the Alaska Coastal Current recorded by coralline algal Ba/Ca ratios

Arctic Ocean freshening can exert a controlling influence on global climate, triggering strong feedbacks on ocean‐atmospheric processes and affecting the global cycling of the world’s oceans. Glacier‐fed ocean currents such as the Alaska Coastal Current are important sources of freshwater for the Bering Sea shelf, and may also influence the Arctic Ocean freshwater budget. Instrumental data indicate a multiyear freshening episode of the Alaska Coastal Current in the early 21st century. It is uncertain whether this freshening is part of natural multidecadal climate variability or a unique feature of anthropogenically induced warming. In order to answer this, a better understanding of past var…

MPI-DING reference glasses for in situ microanalysis: New reference values for element concentrations and isotope ratios

We present new analytical data of major and trace elements for the geological MPI-DING glasses KL2-G, ML3B-G, StHs6/80-G, GOR128-G, GOR132-G, BM90/21-G, T1-G, and ATHO-G. Different analytical methods were used to obtain a large spectrum of major and trace element data, in particular, EPMA, SIMS, LA-ICPMS, and isotope dilution by TIMS and ICPMS. Altogether, more than 60 qualified geochemical laboratories worldwide contributed to the analyses, allowing us to present new reference and information values and their uncertainties (at 95% confidence level) for up to 74 elements. We complied with the recommendations for the certification of geological reference materials by the International Associ…

The compositional variability of eudialyte-group minerals

AbstractEudialyte-group minerals (EGM) represent the most important index minerals of persodic agpaitic systems. Results are presented here of a combined EPMA, Mössbauer spectroscopy and LA-ICP-MS study and EGM which crystallized in various fractionation stages from different parental melts and mineral assemblages in silica over- and undersaturated systems are compared. Compositional variability is closely related to texture, allowing for reconstruction of locally acting magmatic to hydrothermal processes. Early-magmatic EGM are invariably dominated by Fe whereas hydrothermal EGM can be virtually Fe-free and form pure Mn end-members. Hence the Mn/Fe ratio is the most suitable fractionation …

Determination of Reference Values for NIST SRM 610-617 Glasses Following ISO Guidelines

We present new reference values for the NIST SRM 610–617 glasses following ISO guidelines and the International Association of Geoanalysts’ protocol. Uncertainties at the 95% confidence level (CL) have been determined for bulk- and micro-analytical purposes. In contrast to former compilation procedures, this approach delivers data that consider present-day requirements of data quality. New analytical data and the nearly complete data set of the GeoReM database were used for this study. Data quality was checked by the application of the Horwitz function and by a careful investigation of analytical procedures. We have determined quantitatively possible element inhomogeneities using different …

Micro-Raman spectroscopy of pigments contained in different calcium carbonate polymorphs from freshwater cultured pearls

The metastable calcium carbonate polymorph vaterite has recently been found to occur commonly in freshwater cultured pearls from Japan and China. Organic pigment molecules in these vaterite regions of freshwater cultured pearls were analysed by resonance and near-resonance micro-Raman spectroscopy, in single spectra and in mapping modes and are compared with their aragonitic counterparts. Four different excitation wavelengths (487.9, 514.5, 532.2 and 632.8 nm) were used, resulting in differential increase of resolution for the pigments. Although vaterite areas were always lightly coloured (light yellow, light brown or white), ten different pigments were identified and a single colour is for…

The composition of near-solidus melts of peridotite in the presence of CO2 and H2O between 40 and 60 kbar

Abstract Partial melting experiments at 40, 50 and 60 kbar pressure on three peridotite compositions with 0.5–0.63 wt.% H2O and 2.0–3.2 wt.% CO2 added indicate melting temperatures only marginally above continental geotherms. Most experiments were performed on a composition with 1.5 wt.% K2O added, which causes a further decrease of about 40 °C in melting temperature. Melts progress gradually from carbonate-rich to carbonated silicate in composition: near-solidus melts have Ca/(Ca + Mg) of 0.46–0.53, which fall to  30 wt.%) and Al2O3 (  9 wt.%) and concomitant decrease in CaO (> 20 to Partial melts of peridotite with CO2 and H2O are too low in MgO to resemble kimberlites, but will act as ef…

The Palaeoanthropocene – The beginnings of anthropogenic environmental change

Abstract As efforts to recognize the Anthropocene as a new epoch of geological time are mounting, the controversial debate about the time of its beginning continues. Here, we suggest the term Palaeoanthropocene for the period between the first, barely recognizable, anthropogenic environmental changes and the industrial revolution when anthropogenically induced changes of climate, land use and biodiversity began to increase very rapidly. The concept of the Palaeoanthropocene recognizes that humans are an integral part of the Earth system rather than merely an external forcing factor. The delineation of the beginning of the Palaeoanthropocene will require an increase in the understanding and …

Melting phlogopite-rich MARID: Lamproites and the role of alkalis in olivine-liquid Ni-partitioning

Abstract In this study, we show how veined lithospheric mantle is involved in the genesis of ultrapotassic magmatism in cratonic settings. We conducted high pressure experiments to simulate vein + wall rock melting within the Earth's lithospheric mantle by reacting assemblages of harzburgite and phlogopite-rich hydrous mantle xenoliths. These comprised a mica-, amphibole-, rutile-, ilmenite-, diopside (MARID) assemblage at 3–5 GPa and 1325–1450 °C. Melting of the MARID assemblages results in infiltration of melt through the harzburgite, leading to its chemical alteration. At 3 and 4 GPa, melts are high in K2O (> 9 wt%) with K2O/Na2O > > 2 comparable to anorogenic lamproites. Higher pressure…

Trace-element partitioning and boron isotope fractionation between white mica and tourmaline

High-grade metamorphic tourmaline and white mica from the Broken Hill area, NSW, Australia, were analyzed with laser-ablation ICP–MS and ion-probe techniques to investigate the partitioning of trace elements and fractionation of boron isotopes between these two coexisting phases. The results indicate that most trace elements show partition coefficients close to one; only elements such as Zn, Sr, the light rare-earth elements La and Ce, and Th, partition preferentially into tourmaline, whereas Rb, Ba, W, Sn, and Nb and Ta are preferentially partitioned into coexisting mica. The ion-probe measurements demonstrate that boron isotopes are strongly fractionated between mica and tourmaline, with …

Towards understanding isotope variability in elephant ivory to establish isotopic profiling and source-area determination

Abstract We present here new isotopic data (δ 13 C, δ 15 N, δ 18 O, δ 2 H, and δ 34 S) from pulverised ivory powder, measured by continuous flow isotope ratio mass spectrometry from an unprecedented large dataset of 507 ivory samples, derived from twenty-eight African and six Asian elephant range states. The aim of this study is to assess the accuracy of isotopic fingerprinting and to evaluate its forensic potential and limitations to predict the provenance of ivory of unknown origin. We constructed a nominal assignment framework for the African reference samples, consisting of 208 different sites and applied the weighted k -Nearest Neighbor Classifier with reference site as classifier and …

Non-Matrix-Matched Calibration for the Multi-Element Analysis of Geological and Environmental Samples Using 200 nm Femtosecond LA-ICP-MS: A Comparison with Nanosecond Lasers

LA-ICP-MS is one of the most promising techniques for in situ analysis of geological and environmental samples. However, there are some limitations with respect to measurement accuracy, in particular for volatile and siderophile/chalcophile elements, when using non-matrix-matched calibration. We therefore investigated matrix-related effects with a new 200 nm femtosecond (fs) laser ablation system (NWRFemto200) using reference materials with different matrices and spot sizes from 10 to 55 μm. We also performed similar experiments with two nanosecond (ns) lasers, a 193 nm excimer (ESI NWR 193) and a 213 nm Nd:YAG (NWR UP-213) laser. The ion intensity of the 200 nm fs laser ablation was much l…

Structural characterization and chemical composition of aragonite and vaterite in freshwater cultured pearls

AbstractVaterite and aragonite polymorphs in freshwater cultured pearls from mussels of the genus Hyriopsis (Unionidae) were structurally and compositionally characterized by Raman spectroscopy, Micro computer tomography, high resolution field emission scanning electron microscopy, electron microprobe analysis and laser ablation inductively coupled plasma mass spectrometry. The appearance of vaterite in pearls is related to the initial stages of biomineralization, although we demonstrate that vaterite can not be a precursor to aragonite. It is not related to a particular crystal habit and therefore does not have a structural functionality in the pearls. Larger contents of elements typically…

Contrasting types of metasomatism in dunite, wehrlite and websterite xenoliths from Kimberley, South Africa

Abstract Dunite, wehrlite and websterite are rare members of the mantle xenolith suite in the Kimberley kimberlites of the Kaapvaal Craton in southern Africa. All three types were originally residues of extensive melt extraction and experienced varying amounts and types of melt re-enrichment. The melt depletion event, dated by Re–Os isotope systematics at 2.9 Ga or older, is evidenced by the high Mg# (Mg/(Mg + Fe)) of silicate minerals (olivine (0.89–0.93); pyroxene (0.88–0.93); garnet (0.72–0.85)), high Cr# (Cr/(Cr + Al)) of spinel (0.53–0.84) and mostly low whole-rock SiO2, CaO and Al2O3 contents. Shortly after melt depletion, websterites were formed by reaction between depleted peridotit…

The coralline red alga Lithophyllum kotschyanum f. affine as proxy of climate variability in the Yemen coast, Gulf of Aden (NW Indian Ocean)

Abstract Recent investigations have shown the potential of red coralline algae as paleoclimatic archive. A previously unexplored subfamily of coralline algae, the Lithophylloideae, was investigated from the Gulf of Aden (Balhaf, Yemen). Seasonal changes in Mg/Ca, Li/Ca and Ba/Ca composition of Lithophyllum kotschyanum f. affine were investigated by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). For the first time in coralline algae, the Li/Ca composition was analyzed and showed a highly significant and positive correlation with Mg/Ca and SST. Monthly algal Mg/Ca and Li/Ca variations indicate a positive correlation with sea surface temperature (SST), and sea surface…

Petrological characterization of the mantle source of Mediterranean lamproites: Indications from major and trace elements of phlogopite

Lamproites are among the most enigmatic mantle generated melts, and are typically abundant in phlogopite. We investigated the major and trace element chemistry of phlogopite crystals from Mediterranean lamproite occurrences in Spain, Serbia and Turkey. The most primitive lamproite samples were selected in order to evaluate the generation of the different phlogopite populations in their distinct mantle setting(s). Phlogopite hosted in Mediterranean lamproites can be grouped into different compositional arrays on the basis of their major element chemistry using Al2O3, FeOT and TiO2 concentrations. Contents of Cr, F and presumably Ti allow discrimination of the macrocrysts into phlogopite phen…

Evidence from Antarctic mantle peridotite xenoliths for changes in mineralogy, geochemistry and geothermal gradients beneath a developing rift

Abstract Garnet and spinel peridotite xenoliths associated with the Phanerozoic Lambert–Amery Rift in eastern Antarctica contain evidence for several stages in the development of the mantle beneath the rift. Despite the fact that equilibria were only partly attained, a combination of petrography, whole-rock geochemistry, mineral chemistry and thermobarometry can be used to decipher four stages prior to entrainment of the xenoliths in the host magma during the initial stages of the breakup of Antarctica, India and Madagascar. The first chronological stage is represented by harzburgitic protoliths represented by rare occurrences of low-Ca olivines and orthopyroxenes in spinel lherzolites: the…

Bio-vaterite formation by glycoproteins from freshwater pearls

Abstract A 48 kDa acidic and putative calcium-binding glycoprotein was isolated from pearls of the freshwater mussel Hyriopsis cumingii . This protein was compared with a related 46 kDa polypeptide, obtained from the nacreous shell of the same species. Separation by two-dimensional gel electrophoresis revealed that the difference in molecular weight is due to the higher extent of glycosylation of the 48 kDa protein existing in pearls. Evidence is presented that the sugar moieties of the protein contribute to crystal growth, starting with the nucleation step. In in vitro precipitation experiments, the 48 kDa glycoprotein of pearls directed the formation of round-shaped vaterite crystals whil…

Subduction-related origin of eclogite xenoliths from the Wajrakarur kimberlite field, Eastern Dharwar craton, Southern India: Constraints from petrology and geochemistry

Abstract Major and trace elements as well as the first oxygen isotopes are reported on eclogite xenoliths from the Mesoproterozoic KL2 and P3 kimberlite pipes of the Wajrakarur kimberlite field, Eastern Dharwar craton, Southern India. Garnets in kyanite-bearing samples are rich in grossular, whereas they are predominantly pyrope-almandines in the bimineralic (kyanite-free) samples. The kyanite eclogite from the P3 pipe is more Mg-rich than those from KL2 pipe. Equilibration temperatures indicate derivation from 4.5 to 5.3 GPa and 1060 to 1220 °C for the KL2 samples and 3.6 GPa, 918 °C for the P3 sample. Garnet rare earth element patterns show two characteristic types, one with relatively lo…

Rutile crystals as potential trace element and isotope mineral standards for microanalysis

Abstract The present paper reports trace element concentrations of 15 elements (V, Cr, Fe, Zr, Nb, Mo, Sn, Sb, Hf, Ta, W, Lu, Pb, Th and U) as well as Pb and Hf isotope data for four relatively homogeneous and large (centimeter size) rutile grains. Methods employed are SIMS, EMP, LA-ICP-MS, ID-MC-ICP-MS and TIMS. For most elements homogeneity is usually within ± 10% and occasionally variations are even narrower (± 5%), particularly in the core of two of the studied grains. The trace element concentrations of the grains span a broad compositional range (e.g., Zr concentrations are ca. 4, 100, 300 and 800 ppm). Provisional concentration values, calculated based on the homogeneity of the eleme…

Polymer-Functionalised Nanograins of Mg-Doped Amorphous Calcium Carbonate via a Flow-Chemistry Approach

Calcareous biominerals typically feature a hybrid nanogranular structure consisting of calcium carbonate nanograins coated with organic matrices. This nanogranular organisation has a beneficial effect on the functionality of these bioceramics. In this feasibility study, we successfully employed a flow-chemistry approach to precipitate Mg-doped amorphous calcium carbonate particles functionalized by negatively charged polyelectrolytes&mdash

Eclogites and garnet pyroxenites: Similarities and differences

Eclogites and garnet pyroxenites are genetically linked to basaltic precursors. Traditionally garnet pyroxenites are linked to fractionation of basaltic Magmas Over a range of mantle pressures and more recently they have been implicated in the genesis of ocean islands. in contrast eclogites are linked to the subduction of slab basalt and gabbro precursors which may be hydrothermally altered. Recently this subduction paradigm has been questioned. We present mineralogical, trace element and O isotopic data for eclogites and garnet pyroxenites that reveal some similarities but also important chemical and isotopic differences that support a distinct provenance (i.e., age and process). Continent…

The effect of titanite and other HFSE-rich mineral (Ti-bearing andradite, zircon, eudialyte) fractionation on the geochemical evolution of silicate melts

Abstract We present trace element data for HFSE-rich minerals (titanite, eudialyte, Ti-bearing andradite, zircon) from plutonic rocks of the Eocene Tamazeght complex, High Atlas Mountains, Morocco. In most lithologies significant amounts of titanite are present and as such, titanite fractionation played a major role in the evolution of the HFSE budget of the whole complex. By combining our data with published titanite–melt partition coefficients we explore the effects of titanite fractionation on the evolution of geochemical parameters (Zr/Hf, Nb/Ta, La/Lu and Th/U ratios) during differentiation of silicate melts in detail. Based upon this, we further discuss the genetic relationships betwe…

ASSESSING TRACE ELEMENT (DIS)EQUILIBRIUM AND THE APPLICATION OF SINGLE ELEMENT THERMOMETERS IN METAMORPHIC ROCKS

Abstract Empirical and experimental calibration of single element solubility thermometers, such as Zr-in-rutile, Zr-in-titanite, Ti-in-zircon, and Ti-in-quartz, within the past 13 years has greatly expanded our ability to assess the pressure and temperature conditions of individual minerals associated with specific textures in metamorphic rocks. Combined with advances in in situ techniques for analyzing trace concentrations, this has led to an increase in the combined use of single element thermometers, geochronometers, and isotope ratios, often simultaneously, in metamorphic minerals. Here we review the calibration and application of single element thermometers at the pressure and temperat…

Laminated carbonate deposits in Roman aqueducts: Origin, processes and implications

Carbonate deposits in Roman aqueducts of Patara and Aspendos (southern Turkey) were studied to analyse the nature of their regular layering. Optical microscopy and electron-backscattered diffraction results show an alternation of dense, coarsely crystalline, translucent laminae composed of bundles and fans of elongate calcite crystals with their c-axes parallel to the long axis, and porous, fine-grained laminae with crystals at near-random orientation. The ?18O and ?13C data show a strong cyclicity and anti-correlation, whereby high and low ?18O values correspond to dense columnar and porous fine-grained laminae, respectively. Geochemical analyses show similar cyclic changes in carbonate co…

Investigation of matrix effects in 193nm laser ablation-inductively coupled plasma-mass spectrometry analysis using reference glasses of different transparencies

Abstract The degree of transparency of glasses, which depends on the Fe content, may influence the ablation behavior during laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis. To test possible matrix effects when using a 193 nm Nd:YAG laser, we have analyzed transparent and opaque NIST, BAM and USGS reference glasses. These reference materials are ideal for such investigations, because they are well characterized, most elements are homogeneously distributed at the micrometer scale, and their Fe content varies over a very large range, from 16 to 130,000 μg g− 1. Our measurements show that the fractionation factors of refractory and volatile lithophile elements, …

Nonclassical crystallization in vivo et in vitro (I): Process-structure-property relationships of nanogranular biominerals.

A distinct nanogranular fine structure is shared by a wealth of biominerals from several species, classes and taxa. This nanoscopic organization affects the properties and behavior of the biogenic ceramic material and confers on them attributes that are essential to their function. We present a set of structure-relationship properties that are rooted in the nanogranular organization and we propose that they rest on a common pathway of formation, a colloid-driven and hence nonclassical mode of crystallization. With this common modus operandi, we reveal the most fundamental and wide spread process-structure-property relationship in biominerals. With the recent increase in our understanding of…

The Magmatic to Hydrothermal Evolution of the Intrusive Mont Saint-Hilaire Complex: Insights into the Late-stage Evolution of Peralkaline Rocks

The Cretaceous Mont Saint-Hilaire complex (Quebec, Canada) comprises three major rock units that were emplaced in the following sequence: (I) gabbros; (II) diorites; (III) diverse partly agpaitic foid syenites. The major element compositions of the rock-forming minerals, age-corrected Nd and oxygen isotope data for mineral separates and trace element data of Fe-Mg silicates from the various lithologies imply a common source for all units. The distribution of the rare earth elements in clinopyroxene from the gabbros indicates an ocean island basalt type composition for the parental magma. Gabbros record temperatures of 1200 to 800 degrees C, variable silica activities between 0 center dot 7 …

Eclogite xenoliths from Kimberley, South Africa — A case study of mantle metasomatism in eclogites

Abstract Eclogite xenoliths from the Kimberley diamond mine dumps were studied for major, trace elements and oxygen isotopes. The suite consists of typical garnet and clinopyroxene rocks as well as kyanite-eclogites and olivine- or orthopyroxene-bearing samples. All samples have Al[6]/Al[4] ratios > 2 which indicate high equilibration pressures, i.e. in the eclogite stability field as opposed to pyroxenites. Most samples are modally and cryptically metasomatized and contain up to 10 vol.% phlogopite plus ilmenite and rutile. Trace element geochemical characteristics of phlogopite and Ti-oxides are similar to those described for metasomatized peridotite xenoliths from the Kaapvaal craton, an…

Probing the Multiple Structures of Vaterite through Combined Computational and Experimental Raman Spectroscopy.

First-principles Raman spectra have been computed for several new vaterite structural models that have been recently proposed, and compared with spectra recorded on a set of biogenic, geological and synthetic samples. This set includes new measurements collected on Herdamania momus spicules (Great Barrier Reef, Queensland, Australia), which are known to have purity and crystallinity that are higher than for other biogenic samples. Overall, due to the close structural connection between the various models, the computed Raman spectra are found to be broadly similar. However, the spectra obtained for the two most stable models (monoclinic C2 and trigonal P3221, corresponding to two different p…

Combined thermodynamic and rare earth element modelling of garnet growth during subduction: Examples from ultrahigh-pressure eclogite of the Western Gneiss Region, Norway

Abstract Major and trace element zonation patterns were determined in ultrahigh-pressure eclogite garnets from the Western Gneiss Region (Norway). All investigated garnets show multiple growth zones and preserve complex growth zonation patterns with respect to both major and rare earth elements (REE). Due to chemical differences of the host rocks two types of major element compositional zonation patterns occur: (1) abrupt, step-like compositional changes corresponding with the growth zones and (2) compositionally homogeneous interiors, independent of growth zones, followed by abrupt chemical changes towards the rims. Despite differences in major element zonation, the REE patterns are almost…

Amorphous calcium carbonate in the shells of adult Unionoida

Shells of adult individuals from two different bivalve families, Hyriopsis cumingii and Diplodon chilensis patagonicus, were studied by Micro-Raman spectroscopy and Focussed Ion Beam-assisted TEM. The shells contain amorphous calcium carbonate in a zone at the interface between the periostracum and the prismatic layer. In this area, the initial prism structures protrude from the inner periostracum layer and it is demonstrated that these structures systematically consist of highly disordered and amorphous calcium carbonate. Within this zone, ordered and disordered areas are intermingled discounting the existence of a crystallization front and favouring models of domainal crystallization proc…

Rare earth elements in apatite as a monitor of magmatic and metasomatic processes: The Ilímaussaq complex, South Greenland

Abstract Textural and compositional variations of apatite from the plutonic Ilimaussaq complex in South Greenland and its surrounding country rocks track magmatic and metasomatic processes. Detailed back-scattered electron (BSE) imaging reveals various types of apatite textures including (i) growth zonation (concentric, oscillatory as well as sector zonation) formed during magmatic differentiation, (ii) resorption and overgrowth textures due to fluid/melt induced metasomatic overprint of precursor apatite and (iii) replacement textures indicating the destabilization of apatite in favor of monazite. In the least evolved rocks of the Ilimaussaq complex, apatite incorporates rare earth element…

Raman spectroscopy of synthetic, geological and biological vaterite: a Raman spectroscopic study

Raman spectroscopy was used to study vaterite samples of biological, geological and synthetic origin. The Raman band positions and the full width at half-maximum (FWHM) of the lattice modes and the internal modes of the carbonate ion of all specimens show no significant differences between vaterites of different origin. With increasing Mg concentrations, synthetic vaterite samples show increasing FWHM in the region of the lattice modes and the three ν1 bands, whereas no change in luminescence was detected. In contrast, in situ measurements of vaterite areas in freshwater cultured pearls (FWCPs) by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) together with the Rama…

Tropical marine climate during the late Paleozoic ice age using trace element analyses of brachiopods

Abstract The late Paleozoic ice age can be considered an important analogue to the modern ice age, but comparisons between the two time intervals have been hampered by the difficulty of resolving climatic changes that occur over short (e.g., seasonal) time scales in the Paleozoic record. As a first step toward overcoming these limitations, this study employed Mg/Ca trace element ratios sampled across the growth bands of six specimens of the brachiopod Composita to assess differences in tropical marine mean temperature and seasonality in Visean and Moscovian time. These time intervals bracket the onset of the late Paleozoic ice age, which occurred in mid-Serpukhovian time, and thus provide a…

Nano-inclusion suite and high resolution micro-computed-tomography of polycrystalline diamond (framesite) from Orapa, Botswana

Abstract A single polycrystalline diamond aggregate from the Orapa kimberlite (Botswana) contains a syngenetic micro- and nano-inclusion suite of magnetite, pyrrhotite, omphacite, garnet, rutile and C–O–H fluid in order of abundance. This suite of inclusions is distinctly different from those in fibrous diamonds, although the presence of sub-micrometer fluid inclusions provides evidence for a similarly important role of fluids in the genesis of polycrystalline diamond. It is the first study of polycrystalline diamond by High resolution μ-CT (Computed Tomography) reaching a resolution of 1.3 μm using polychromatic X-rays. Combined with Focused Ion Beam assisted Transmission Electron Microsco…

A Pearl Identification Challenge

Element variability in the coralline alga Lithophyllum yemenense as archive of past climate in the Gulf of Aden (NW Indian Ocean)

This study presents the first algal thallus (skeleton) archive of Asian monsoon strength and Red Sea influence in the Gulf of Aden. Mg/Ca, Li/Ca, and Ba/Ca were measured in Lithophyllum yemenense from Balhaf (Gulf of Aden) using laser ablation inductively coupled plasma mass spectrometry, and Mg/Ca ratio oscillation was used to reconstruct the chronology (34 y). Oscillations of element rates corresponding to the algal growth between 1974 and 2008 were compared with recorded climate and oceanographic variability. During this period, sea surface temperatures (SST) in Balhaf recorded a warming trend of 0.55 degrees C, corresponding to an increase in Mg and Li content in the algal thallus of 2.…

Cold plumes trigger contamination of oceanic mantle wedges with continental crust-derived sediments: Evidence from chromitite zircon grains of eastern Cuban ophiolites

The origin of zircon grains, and other exotic minerals of typical crustal origin, in mantle-hosted ophiolitic chromitites are hotly debated.We report a population of zircon grains with ages ranging from Cretaceous (99 Ma) to Neoarchean (2750 Ma), separated from massive chromitite bodies hosted in the mantle section of the supra-subduction (SSZ)-type Mayarí-Baracoa Ophiolitic Belt in eastern Cuba. Most analyzed zircon grains (n = 20, 287 +/- 3 Ma to 2750 +/- 60 Ma) are older than the early Cretaceous age of the ophiolite body, show negative εHf(t) (+/-26 to +/-0.6) and occasional inclusions of quartz, K-feldspar, biotite, and apatite that indicate derivation from a granitic continental crust…

Eclogites and Garnet Pyroxenites: Problems Resolving Provenance Using Lu-Hf, Sm-Nd and Rb-Sr Isotope Systems

Cratonic eclogites and garnet pyroxenites from the Kaapvaal craton have heterogeneous Hf^Nd^Sr^(O) isotope ratios that define a positive Hf^Nd isotope array and a negative Nd^Sr isotope array. Isotopic variability encompasses depleted (mid-ocean ridge basalt and ocean-island basalt) to enriched mantle compositions (Group I and II kimberlites) and overlaps with that of the Kaapvaal craton garnet peridotite xenoliths. Isotopic heterogeneity at Roberts Victor is less extreme than previously reported and ranges from eclogites with a highly depleted MORB-like signature to enriched eclogites similar to Group II and transitional kimberlites and Group II megacrysts (eHf1⁄4 ^32·8). Much of this simi…

Goldschmidt Abstracts 2010 – R

Seasonal periodicity of growth and composition in valves of Diplodon chilensis patagonicus (d'Orbigny, 1835)

Freshwater mussels of the genus Diplodon (Unionida) are common inhabitants of lakes and rivers in South America, and have slow growth and long life spans. We established the annual periodicity of incremental shell growth in Diplodon chilensis patagonicus (d'Orbigny, 1835) and calculated growth rates at different ages, using internal ring counting supported by dyeing methods and δ 18 O isotope analyses, in two Patagonian populations (Lago Steffen and its effluent Rio Manso Inferior, Argentina). Longevities of ca. 90 years (Lago Steffen) significantly extend the life spans reported in the past. Growth rates for old individuals (>30 years) from both lake and river populations average 0.16 mm p…

Nature and origin of eclogite xenoliths from kimberlites

Abstract Eclogites from the Earth's mantle found in kimberlites provide important information on craton formation and ancient geodynamic processes because such eclogites are mostly Archean in age. They have equilibrated over a range of temperatures and pressures throughout the subcratonic mantle and some are diamond-bearing. Most mantle eclogites are bimineralic (omphacite and garnet) rarely with accessory rutiles. Contrary to their overall mineralogical simplicity, their broadly basaltic-picritic bulk compositions cover a large range and overlap with (but are not identical to) much younger lower grade eclogites from orogenic massifs. The majority of mantle eclogites have trace element geoc…

Terpenoid composition and origin of amber from the Cape York Peninsula, Australia

The terpenoid composition of fossil resin from the Cape York Peninsula, Australia has been analysed by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) to determine its origin. The pyrolysis products were dominated by cadalene-based C15 bicyclic sesquiterpenoids including some C30–C31 bicadinanes and bicadinenes typical of Class II resin derived from angiosperm plants of Dipterocarpaceae. This observation contrasts with the Araucariaceae (Agathis sp.) source previously suggested for the resin based on Fourier transform infrared (FTIR) analyses. Dipterocarpaceae are not known in Australian vegetation but grow abundantly in Southeast Asia including New Guinea, indicating that the geo…

Mineral and trace element composition of the Lokpanta oil shales in the Lower Benue Trough, Nigeria

Abstract The concentrations of minerals and trace elements in the Lokpanta oil shale from the Lower Benue Trough, Nigeria have been determined by X-ray diffraction (XRD) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), respectively. X-ray diffraction data were evaluated using the SIROQUANT™ interactive data processing system based on Rietveld interpretation methods. A new method of trace element determination in oil shale, involving LA-ICP-MS analysis of glass beads prepared by fusing oil shale ash on an iridium strip heater was used, and the accuracy of the method was assessed by including a standard shale reference material (SGR-1b) in the analysis program. The…

Rubies and Sapphires from Snezhnoe, Tajikistan

Restoration of premetasomatic protolith compositions in mantle xenoliths

Minor and trace elements in olivines as probes into early igneous and mantle melting processes

Abstract The trace element composition of olivine is a rapidly growing research area that has several applications of great potential. Mantle olivines can be distinguished from volcanic olivines by lower concentrations of Ca (

Towards the development of a fossil bone geochemical standard: An inter-laboratory study

Ten international laboratories participated in an inter-laboratory comparison of a fossil bone composite with the objective of producing a matrix and structure-matched reference material for studies of the bio-mineralization of ancient fossil bone. We report the major and trace element compositions of the fossil bone composite, using in-situ method as well as various wet chemical digestion techniques. For major element concentrations, the intra-laboratory analytical precision (%RSDr) ranges from 7 to 18%, with higher percentages for Ti and K. The %RSDr are smaller than the inter-laboratory analytical precision (%RSDR; 100% was found for the high field strength elements (Hf, Th, Zr, Nb). The…

Geochemistry of Chromian Spinels from the Indo-Myanmar Ophiolite Belt of Northeastern India

Chromite is commonly used for deciphering the petrogenesis and geodynamic setting of ultramafic rocks. Chromespinels from the Indo-Myanmar ophiolite belt occurring in the form of podiform chromitites associated with the mantle sequence and associated volcanic rocks are studied to characterise their geochemical composition. We have measured major and trace element concentrations of the chrome-spinels. Cr/(Cr+Al) (Cr#) and Mg/(Mg+Fe 2+ ) (Mg#) range from 66 to 70 and 66 to 69 respectively in the chromitite and 47 to 56 and 67 to 70 in volcanic spinel. The computed crystallization conditions show that the studied samples crystallized in an upper mantle environment. Using the chrome spinel comp…

Manganese speciation inDiplodon chilensis patagonicusshells: a XANES study

X-ray absorption near-edge spectroscopy (XANES) at the Mn K-edge was used to investigate the environment of Mn in situ within the growth increments of the long-lived freshwater bivalve species Diplodon chilensis patagonicus. Single XANES spectra and Mn Kalpha fluorescence distributions were acquired at submillimetre resolution (up to 100 microm x 50 microm), at Mn concentrations below the weight percent range (100-1000 microg g(-1)) in a high Ca matrix. The position and intensity of the pre-edge feature in the shell spectrum resembles best that of the Mn(II)-bearing reference compounds, suggesting that this is the oxidation state of Mn in the bivalve shells. By comparison with the XANES spe…

Crystal fabrics and element impurities (Sr/Ca, Mg/Ca, and Ba/Ca) in shells of Arctica islandica—Implications for paleoclimate reconstructions

Sr/Ca, Mg/Ca and Ba/Ca values are heterogeneously distributed in shells of Arctica islandica. These patterns are largely associated with crystal fabrics (size, habit and orientation of crystals) or the processes controlling them. The outer sublayer of the outer shell layer (oOSL; homogenous and irregular simple prismatic crystal fabrics,) contained element/Ca values up to 62% higher than the inner sublayer (iOSL; crossed-acicular, crossed-lamellar, fine crossed-lamellar and irregular simple prismatic crystal fabrics). A gradual decrease in Sr/Ca and Mg/Ca values was observed from the outer portions of the oOSL toward the oOSL/iOSL transition zone. This chemical shift was accompanied by a gr…

Accurate trace element analysis of speleothems and biogenic calcium carbonates by LA-ICP-MS

The high spatial resolution of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) microanalysis of speleothems and biogenic calcium carbonates makes it possible to improve our understanding of past climatic conditions. However, there are analytical problems associated with this method, such as molecular interferences, elemental fractionation, and mass-load-dependent matrix effects, when using NIST silicate reference glasses for calibration. Our study with a sector-field ICP-MS shows that many masses are affected by interferences, such as 24Mg+ by 48Ca++ or 31P+ by 15N16O+. Elemental fractionation and mass-load-dependent matrix effects have been detected for both 213 and…

Nanostructure, composition and mechanisms of bivalve shell growth

Abstract Freshwater and marine cultured pearls form via identical processes to the shells of bivalves and can therefore serve as models for the biomineralization of bivalve shells in general. Their nanostructure consists of membrane-coated granules (vesicles) which contain amorphous calcium carbonate (ACC) at the beginning of the biomineralization sequence, preceding the crystallization of aragonite and vaterite. In contrast to the commonly accepted view, crystallization of ACC occurs rapidly and within the granular nano-compartments mediated by organic molecules much earlier than platelet formation. The interlamellar organic sheets in nacre that form the platelet structure of nacre themsel…

A Look Inside a Remarkably Large Beaded South Sea Cultured Pearl

Quantitative Estimation of Major and Trace Elements in Coals of the Benue Trough, Nigeria

The concentrations of major and trace elements in ash residues of coals of the Benue Trough, Nigeria have been determined by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry, respectively. Major and trace element determination in rocks by fusion on an iridium strip heater followed by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry is extended here to coal ash, and the accuracy of the method is evaluated by including an Argonne Premium Coal reference sample in each analysis program. Si and Al are the major elements detected in the coal ashes. An assessment using worldwide concentration ranges of trace elements in coal ash…

The olivine macrocryst problem: New insights from minor and trace element compositions of olivine from Lac de Gras kimberlites, Canada

This study presents detailed petrographical and geochemical investigations on remarkably fresh olivines in kimberlites from the EKATI Diamond Mine™ located in the Tertiary/Cretaceous Lac de Gras kimberlite field within the Slave craton of Canada. Olivine, constituting about 42 vol.% of the analyzed samples, can be divided into two textural groups: (i) macrocrystic olivines, > 100 μm sub-rounded crystals and (ii) groundmass olivines, < 100 μm subhedral crystals. Olivines from both populations define two distinct chemical trends; a “mantle trend” with angular cores, showing low Ca (< 0.1 wt.% CaO) and high Ni (0.3–0.4 wt.% NiO) at varying Mg# (0.86–0.93), contrasts with a “melt trend” typifie…

Major and trace element compositions (including REE) of mineral, thermal, mine and surface waters in SW Germany and implications for water–rock interaction

Abstract The near-surface water cycle in a geologically complex area comprises very different sources including meteoric, metamorphic and magmatic ones. Fluids from these sources can react with sedimentary, magmatic and/or metamorphic rocks at various depths. The current study reports a large number of major, minor and trace element analyses of meteoric, mineral, thermal and mine waters from a geologically well-known and variable area of about 200 × 150 km in SW Germany. The geology of this area comprises a Variscan granitic and gneissic basement overlain in parts by Triassic and Jurassic shales, sandstones and limestones. In both the basement and the sedimentary rocks, hydrothermal mineral…

Coralline algal growth-increment widths archive North Atlantic climate variability

Over the past decade coralline algae have increasingly been used as archives of paleoclimate information. Encrusting coralline algae, which deposit annual growth increments in a high Mg-calcite skeleton, are amongst the longest-lived shallow marine organisms. In fact, a live-collected plant has recently been shown to have lived for at least 850 years based on radiometric dating. While a number of investigations have successfully used geochemical information of coralline algal skeletons to reconstruct sea surface temperatures, less attention has been paid to employ growth increment widths as a temperature proxy. Here we explore the relationship between growth and environmental parameters in …

Effect of organic matrices on the determination of the trace element chemistry (Mg, Sr, Mg/Ca, Sr/Ca) of aragonitic bivalve shells (&lt;i&gt;Arctica islandica&lt;/i&gt;)&amp;mdash;Comparison of ICP-OES and LA-ICP-MS data

The element chemistry of biogenic carbonates can provide important data on past environments. However, the Sr/Ca and Mg/Ca ratios as well as the Mg and Sr concentrations of biological carbonates, especially aragonitic bivalves often depart from apparent thermodynamic equilibrium. When measured in situ by means of LA-ICP-MS, the Mg concentration is often substantially enriched (two- to threefold) near the organic-rich, annual growth lines. To test the hypothesis that some organic components exert a major influence on the skeletal metal content, the element chemistry of different shell components (insoluble organic matrix, IOM; dissolved CaCO3 and soluble organics, SOM) of Arctica islandica w…

Re-enrichment of cratonic lithospheric mantle beneath an evolving rift: Mantle xenoliths from East Antarctica

Terpenoid composition and chemotaxonomic aspects of Miocene amber from the Koroglu Mountains, Turkey

Abstract A recently discovered fossil resin from Koroglu Mountain in Turkey has been analyzed by gas chromatography–mass spectrometry and pyrolysis gas chromatography–mass spectrometry to determine its structural class and botanical origin. The sesqui- and diterpenoids contained in the amber extract were used as chemosystematic markers when compared with terpenoids in extant conifers. The pyrolysis products were dominated by labdanoid derived bicyclic products together with succinic acid indicating Class Ia type amber. The biomarker compositions of the resin comprise mainly sesqui- and diterpenoids, and lack triterpenoids. This distribution suggests a gymnosperm, and more specifically a con…

Amorphous, nanocrystalline and crystalline calcium carbonates in biological materials

Raman spectroscopy is a powerful tool in identifying different calcium carbonate polymorphs. Here, the method is applied to cultured pearls from freshwater (genus Hyriopsis) and marine bivalve species (Pinctada maxima) as well as to shells of Diplodon chilensis patagonicus bivalves. Raman spectra for vaterite, detected for the first time in an adult shell, and amorphous calcium carbonate (ACC) are discussed. Results for ACC are compared with those of synthetically produced ACC and with the Raman spectroscopic features of stable biogenic ACC from the crustacean Porcellio scaber. Decomposition of the most intense signal of all calcium carbonate polymorphs—the ν1 symmetric stretching mode of t…

Novel findings in patients with primary hyperoxaluria type III and implications for advanced molecular testing strategies

Identification of mutations in the HOGA1 gene as the cause of autosomal recessive primary hyperoxaluria (PH) type III has revitalized research in the field of PH and related stone disease. In contrast to the well-characterized entities of PH type I and type II, the pathophysiology and prevalence of type III is largely unknown. In this study, we analyzed a large cohort of subjects previously tested negative for type I/II by complete HOGA1 sequencing. Seven distinct mutations, among them four novel, were found in 15 patients. In patients of non-consanguineous European descent the previously reported c.700+5G>T splice-site mutation was predominant and represents a potential founder mutation, w…

Akoya Cultured Pearl Farming in Eastern Australia

Anatectic amphibole and restitic garnet in Variscan migmatite from NE Sardinia, Italy: insights into partial melting from mineral trace elements

We report results of a laser-ICP-MS investigation of trace element contents in the main constituent minerals of an amphibole-bearing migmatite from the Variscan orogen in northeastern Sardinia. The migmatite is associated with migmatised orthogneiss and Al-silicate-bearing pelitic migmatites. The protolith of the amphibole-bearing migmatite was a mid-Ordovician igneous rock of intermediate composition characterised by a biotite + plagioclase + quartz assemblage. The migmatite consists of mesosomes and tonalitic (or, less frequently, granodioritic) leucosomes, characterised by amphibole crystals (potassian ferropargasite) up to 2 cm in size. The tonalitic leucosomes are made up of quartz, pl…

Nano‐Powdered Calcium Carbonate Reference Materials: Significant Progress for Microanalysis?

THE REDISTRIBUTION OF RARE-EARTH ELEMENTS IN SECONDARY MINERALS OF HYDROTHERMAL VEINS, SCHWARZWALD, SOUTHWESTERN GERMANY

Minerals of the rare-earth elements (REE) occur as supergene phases in the Schwarzwald ore district, southwestern Germany. They form by alteration of hydrothermal fluorite – barite – quartz – carbonate veins with various associations, including Cu– Pb, Pb–Zn and Co–Bi–Ag–U assemblages in sandstones, gneisses and granites. The REE minerals, including mixite-group minerals ([REE,Bi,Ca,Pb]Cu 6 (AsO 4 ,AsO 3 OH) 3 OH 6 •3H 2 O), rhabdophane and churchite (REEPO 4 •H 2 O and REEPO 4 •2H 2 O), chukhrovite (Ca 3 REEAl 2 SO 4 F 13 •10H 2 O) and bastnasite (REECO 3 F), were analyzed by electron microprobe and LA–ICP–MS. In addition, REE concentrations in secondary fluorite, calcite and Mn oxides cog…

Designed peptides for biomineral polymorph recognition: a case study for calcium carbonate

With their unique ability for substrate recognition and their sequence-specific self-assembly properties, peptides play an important role in controlling the mineralization of inorganic materials in natural systems and in controlling the assembly of soft materials into complex structures required for biological functions. Here we report the use of an engineered heptapeptide that can differentiate between the crystalline anhydrous polymorphs of calcium carbonate. This peptide contains the positively charged amino acid arginine as well as proline rather than the prototypical negatively charged aspartate or glutamate units. Its affinity to vaterite compared to aragonite was demonstrated by fluo…

Mg/Ca ratios in coralline algae record northwest Atlantic temperature variations and North Atlantic Oscillation relationships

Climate variability in the North Atlantic has been linked in part to the North Atlantic Oscillation (NAO). The NAO influences marine ecosystems in the northwestern Atlantic and transport variability of the cold Labrador Current. Understanding historic patterns of NAO variability requires long‐term and high‐resolution climate records that are not available from instrumental data. Here we present the first century‐scale proxy record of sea surface temperature (SST) variability from the Newfoundland shelf, a region from which other annual‐resolution shallow marine proxies are unavailable. The 116 year record was obtained from three sites along the eastern Newfoundland shelf using laser ablatio…

High-resolution analysis of trace elements in crustose coralline algae from the North Atlantic and North Pacific by laser ablation ICP-MS

We have investigated the trace elemental composition in the skeleta of two specimens of attached-living coralline algae of the species Clathromorphum compactum from the North Atlantic (Newfoundland) and Clathromorphum nereostratum from the North Pacific/Bering Sea region (Amchitka Island, Aleutians). Samples were analyzed using Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) yielding for the first time continuous individual trace elemental records of up to 69 years in length. The resulting algal Mg/Ca, Sr/Ca, U/Ca, and Ba/Ca ratios are reproducible within individual sample specimens. Algal Mg/Ca ratios were additionally validated by electron microprobe analyses (Amch…

Recycling plus: A new recipe for the formation of Alpine-Himalayan orogenic mantle lithosphere

Abstract The origin of the lithospheric mantle beneath accretionary orogens is enigmatic; although severe compression of the buoyant crust occurs, the mantle lithosphere is generally thought to be removed and returned to the convecting mantle. We suggest that during the accretion of oceanic arcs and small continental blocks in the Mediterranean region, and more generally throughout the whole Alpine–Himalayan orogenic belt, the mantle lithosphere is newly created and composed of intimately mixed peridotite and crustal material from the forearc region. Potassium-rich volcanic rocks emplaced sometimes more than 30 Ma after the formation of this lithosphere carry evidence for the presence of ex…

HYDROTHERMAL CARBONATES OF THE SCHWARZWALD ORE DISTRICT, SOUTHWESTERN GERMANY: CARBON SOURCE AND CONDITIONS OF FORMATION USING  18O,  13C, 87Sr/86Sr, AND FLUID INCLUSIONS

Diagenetic carbonates, metamorphic carbonates, primary hydrothermal carbonates, and secondary remobilized carbonates (including sinters) from the Schwarzwald ore district in SW Germany formed in various tectonic settings and hydrothermal environments over a period of almost 300 Ma. They were investigated in order to define sources of carbon, dispersion of carbon during fluid-rock interaction processes and, where possible, to specify geochemical fingerprints for carbonates formed during different processes and in different geochemical and tectonic environments. For this purpose, 335 samples of calcite, ankerite, dolomite, siderite, and strontianite from 92 localities in 46 mining areas in th…

SHRIMP ZIRCON AGES AND PETROLOGY OF LOWER CRUSTAL GRANULITE XENOLITHS FROM THE LETSENG-LA-TERAE KIMBERLITE, LESOTHO: FURTHER EVIDENCE FOR A NAMAQUA-NATAL CONNECTION

Recrystallized zircons extracted from intermediate granulites of the Letseng-la-Terae Diamond Mine in northeastern Lesotho provide evidence that the Tugela Terrane of the Mesoproterozoic high-grade Namaqua-Natal mobile belt may extend ~200 km farther west than previously thought. The rock-forming minerals in the investigated lower crustal granulites contain garnet, clinopyroxene, plagioclase and quartz or garnet, wollastonite, plagioclase and quartz. Calculated values for peak granulite-facies metamorphism are ~13 kbar and ~850°C. Thermal overprint and therein granulite-facies metamorphism occurred during the late Mesoproterozoic and is documented by SHRIMP metamorphic zircon ages of 1018 ±…

The geochemistry of Tl and its isotopes during magmatic and hydrothermal processes: The peralkaline Ilimaussaq complex, southwest Greenland

Abstract We use thallium (Tl) concentrations, K/Rb, K/Tl and Rb/Tl ratios and Tl isotopes in minerals from the alkaline to peralkaline Ilimaussaq complex (South Greenland) to trace magmatic differentiation, crustal assimilation, magmatic degassing, ore precipitation and hydrothermal metasomatism. Closed-system magmatic differentiation is marked by a coherent decrease of K/Tl- and K/Rb-ratios, whereas crustal assimilation results in a strong Tl-enrichment, causing low K/Tl-ratios compared to K/Rb-ratios. Thallium isotopes show only slight changes during orthomagmatic differentiation and the assimilation of crustal material cannot be traced, since the isotopic composition of the average crust…

Eclogite xenoliths from the Kuruman kimberlites, South Africa: geochemical fingerprinting of deep subduction and cumulate processes☆

The mineralogically diverse eclogite xenolith suite sampled by the >1.6 Ga Zero kimberlite in the Kuruman group, close to the western edge of the Kaapvaal craton consists of bimineralic eclogites, orthopyroxene-bearing eclogites with and without sanidine, and kyanite eclogites. Garnet exsolutions in clinopyroxene occur in all Zero eclogite types, and orthopyroxene and, where present, sanidine are also exsolved from clinopyroxene in orthopyroxene-bearing eclogites. Mineral thermobarometry indicates that the last P–T condition prior to the kimberlite eruption was 900–950 °C at 3.5–4.0 GPa. However, inclusions of quartz, rutile and rarely K-feldspar, plus former fluid inclusions in garnets, in…

Trace element systematics of tourmaline in pegmatitic and hydrothermal systems from the Variscan Schwarzwald (Germany): The importance of major element composition, sector zoning, and fluid or melt composition

article An extensive data set on the compositional variation of tourmaline from granitic pegmatites, from migmatitic gneisses and from various types of hydrothermal veins from the Schwarzwald, Germany, is provided. The investigated tourmalines are members of the alkali and X-vacant groups representing mostly dravite- schorl solid solutions with some analyses belonging to the foitite-Mg-foitite series. Oxygen isotope data on quartz-tourmaline pairs indicate formation temperatures between 550 and 350 °C for most of the quartz-tourmaline veins. Most of the tourmalines show strong sector zonation, fractionating certain major (e.g., Na, Mg), minor (e.g., Ti, Ca) and trace elements (e.g., Sr, Pb,…

Melting and dynamic metasomatism of mixed harzburgite + glimmerite mantle source: Implications for the genesis of orogenic potassic magmas

Abstract Tectonically young, orogenic settings are commonly the sites of post-collisional silica-rich ultrapotassic magmas with extreme K2O-contents of up to 9 wt% and K2O/Na2O > 2. Many experimental studies investigating the generation of these melts have concentrated on melting of homogenous phlogopite bearing peridotites, whereas geochemical signatures indicate the involvement of at least two types of source rocks: ultra-depleted and K and trace elements-enriched ones. We report the results of melting experiments at 1–2 GPa of mixed glimmerite and harzburgite, in which these rock types make up two halves each capsule. Melting begins in the glimmerite, and its metasomatic effects on the h…

Coralline algal Barium as indicator for 20th century northwestern North Atlantic surface ocean freshwater variability

During the past decades climate and freshwater dynamics in the northwestern North Atlantic have undergone major changes. Large-scale freshening episodes, related to polar freshwater pulses, have had a strong influence on ocean variability in this climatically important region. However, little is known about variability before 1950, mainly due to the lack of long-term high-resolution marine proxy archives. Here we present the first multidecadal-length records of annually resolved Ba/Ca variations from Northwest Atlantic coralline algae. We observe positive relationships between algal Ba/Ca ratios from two Newfoundland sites and salinity observations back to 1950. Both records capture episodi…

Assigning Elephant Ivory with Stable Isotopes

The international ivory trade remains one of the world’s most controversial wildlife trade issues. One of the main arguments for the trade prohibition is the fact that it is very difficult to distinguish legal from illegal ivory in the markets, so that the legal ivory trade would provide a perfect cover for smuggling. The purpose of this study was to analyze the variability of isotope ratios in ivory samples from Appendix I and II elephant populations in Africa to validate their potential for forensic purposes more quantitatively. We selected a subset of 293 data of ivory samples from the www.ivoryid.org database that stores isotopic ratios of δ13C, δ15N, δ18O, δ2H, and δ34S from more than …