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We present new partition coefficients for various trace elements including Cl between olivine, pyroxenes, amphibole and coexisting chlorine-bearing aqueous fluid in a series of high-pressure experiments at 2 GPa between 900 and 1,300°C in natural and synthetic systems. Diamond aggregates were added to the experimental capsule set-up in order to separate the fluid from the solid residue and enable in situ analysis of the quenched solute by LA-ICP-MS. The chlorine and fluorine contents in mantle minerals were measured by electron microprobe, and the nature of OH defects was investigated by infrared spectroscopy. Furthermore, a fluorine-rich olivine from one selected sample was investigated by TEM. Results reveal average Cl concentrations in olivine and pyroxenes around 20 ppm and up to 900 ppm F in olivine, making olivine an important repository of halogens in the mantle. Chlorine is always incompatible with Cl partition coefficients [D.sup.olivine/fluid.sub.Cl] varying between [10.sup.-5] and [10.sup.-3], whereas [D.sup.orthopyroxene/fluid.sub.Cl] and [D.sup.clinopyroxene/fluid.sub.Cl] are ~[10.sup.-4] and [D.sup.amphibole/fluid.sub.Cl] is ~5 x [10.sup.-3]. Furthermore, partitioning results for incompatible trace element show that compatibilities of trace elements are generally ordered as [D.sup.amph/fluid] ≅ [D.sup.cpx/fluid] > [D.sup.opx/fluid] > [D.sup.ol/fluid] but that [D.sup.mineral/fluid] for Li and P is very similar for all observed silicate phases. Infrared spectra of olivine synthesized in a F-free Tibearing system show absorption bands at 3,525 and ~ 3,570 [cm.sup.-1]. In F ± Ti[O.sub.2]-bearing systems, additional absorption bands appear at ~ 3,535, ~ 3,595, 3,640 and 3,670 [cm.sup.-1]. Absorption bands at ~ 3,530 and ~3,570 [cm.sup.-1], previously assigned to humite-like point defects, profit from low synthesis temperatures and the presence of F. The presence of planar defects could not be proved by TEM investigations, but dislocations in the olivine lattice were observed and are suggested to be an important site for halogen incorporation in olivine. Keywords Halogens * Trace element partitioning * Mantle * Defects * TEM, Introduction Mantle minerals such as olivine, ortho- and clinopyroxene can host up to several hundreds ppm water (Rauch and Keppler 2002; Hirschmann et al. 2005; Stalder et al. 2005, 2008; [...]

High-resolution laser ablation--inductively coupled plasma--mass spectroscopy scanning of resin-embedded laminated sediments is used to detail variability in the composition and magnitude of recent eolian dust deposition in the Eastern Mediterranean. The composition of dust accumulating in the anoxic Atalante basin varies in response to the strength of the summer blocking mode of Mediterranean climate. Dust sources located upwind on the westerly airflow are favored during phases of weaker blocking (hence stronger summer westerlies). This mode is in turn correlated to the pronounced multidecadai oscillation in Mediterranean sea-surface temperature (related to the Atlantic Multidecadal Oscillation), suggesting that coupled ocean-atmosphere dynamics control the large-scale transport of dust in the region. Variable precipitation in dust source regions may also exert an influence on the relative flux of dust from each source, and hence the net composition of dust deposited in the basin. Persistent oscillations in the composition of deeper sediments indicate that the basin offers a high-potential archive for reconstruction of climate-controlled variability in dust transport prior to the instrumental era. doi: 10.1130/G25287.1

The relationship between magnetic properties and chemical composition of 19 natural carbonate single crystals of the calcite, aragonite, and dolomite groups and of azurite were investigated. Magnetic susceptibility was determined in low fields, and magnetic anisotropy was measured at room temperature and at 77 K using a high-field torque magnetometer. The chemical composition was analyzed using LA-ICP MS. Planar arrangement of the C[O.sub.3]-groups generates an oblate diamagnetic anisotropy with the minimum susceptibility [k.sub.3] along the crystallographic c-axis in all investigated anhydrous carbonate minerals. A prolate paramagnetic anisotropy with the maximum susceptibility [k.sub.1] along the c-axis is produced by [Fe.sup.2+] in the trigonal carbonate lattice, which can lead to a transition from oblate to prolate shape of the total anisotropy. The transition occurs in the calcite structure above an Fe concentration of 400 ppm at room temperature and 150 ppm at 77 K. The susceptibility difference [k.sub.1]-[k.sub.3] for pure calcite is 4.06 x [10.sup.-10] [m.sup.3]/kg and increases to 9.4 x [10.sup.-9] [m.sup.3]/kg for 10800 ppm Fe. In the hexagonal aragonite structure, no paramagnetic anisotropy due to [Fe.sup.2+] was detected. Azurite shows a strong anisotropy with [k.sub.1]-[k.sub.3] = 1.5 x [10.sup.-8] [m.sup.3]/kg, which is assigned to [Cu.sup.2+]. The paramagnetic anisotropy due to [Fe.sup.2+] increases at 77 K in minerals of the calcite and dolomite group and in azurite, but not in minerals of the aragonite group. Upon cooling from room temperature to 77 K, [k.sub.1]-[k.sub.3] increases 13.3 times for 500 ppm to 100 000 ppm [Fe.sup.2+] in the trigonal lattice and 7.2 times for siderite. Keywords: Carbonate minerals, magnetic properties, anisotropy, calcite, siderite, rhodochrosite, LA ICP-MS

The capabilities of a millisecond pulsed glow discharge time-of-flight mass spectrometer for the quantitative analysis of organic molecules were investigated. Mixtures of analytes were separated by gas chromatography, and mass spectra were collected at three different time regimes during the pulse cycle--the prepeak, plateau, and afterpeak time regimes. Elemental information was collected in the prepeak, structural information in the plateau, and molecular ion information in the afterpeak. A sample mixture containing toluene, o-xylene, o-dichlorobenzene, and a binary mixture of methanol and sec-butanol were considered. Calibration curves were constructed for each time regime based on the intensities of the elemental, fragment, and molecular ions. Optimum linearity ([r.sup.2] = 0.999) was achieved during the plateau time regime, although calibration in the prepeak was also demonstrated, albeit with slightly poorer correlation coefficients ([r.sup.2] > 0.959). The minimum limits of detection (MDL) were 392, 422, and 557 ng, for toluene, o-xylene, and o-dichlorobenzene, respectively, using a 3-[micro]L injection and a split ratio of 68:1. For the binary alcohol mixture, MDLs of 1.87 and 2.44 [micro]g were determined for methanol and sec-butanol, respectively, based on the intensity of the [sup.16][O.sup.+] ion during the prepeak and using a split ratio of 58:1.

The crystal structure of the rare hexagonal mineral painite [a = 8.724(1), c = 8.464(2) [Angstrom]] from Mogok (Myanmar), with the ideal composition CaZrB[[Al.sub.9][O.sub.18]], was re-determined by single-crystal X-ray diffraction. Structure refinements were performed in space groups P[6.sub.3]/m and P[6.sub.3]. The centrosymmetric P[6.sub.3]/m model yielded excellent agreement ([R.sub.1] = 1.44%, 1189 reflections > 2[alpha] [I.sub.obs], 54 parameters) with the observed diffraction data without any unusual atomic displacement parameters, thus the acentric P[6.sub.3] model was rejected. A previous structural study claimed that painite was noncentrosymmetric and differed from the related structures of jeremejevite [B.sub.5][[cube root of (term)].sub.3][Al.sub.6][(OH).sub.3][O.sub.15]] and fluoborite [B.sub.3][[Mg.sub.9][(F,OH).sub.9][O.sub.9]] in having lower symmetry. The structure of painite comprises a framework of Al[O.sub.6] octahedra that features two types of channels parallel to the c axis. One channel has a trigonal cross-section and is occupied by threefold coordinated B and Zr in sixfold prismatic coordination. The other channel has a hexagonal cross-section and is occupied by Ca. Chemical analysis by laser-ablation inductively-coupled plasma-mass spectrometry indicated that the crystal studied has significant substitution of Na for Ca (ca. 20%) charge-balanced by [Ti.sup.4+] replacing octahedral Al leading to the formula [Ca.sub.0.77] [Na.sub.0.19][Al.sub.8.80][Ti.sub.0.19][Cr.sub.0.03][V.sub.0.01] [Zr.sub.0.94][Hf.sub.0.01][B.sub.1.06][O.sub.18].

In the anoxic Cariaco Basin of the southern Caribbean, the bulk titanium content of undisturbed sediment reflects variations in riverine input and the hydrological cycle over northern tropical South America. A seasonally resolved record of titanium shows that the collapse of Maya civilization in the Terminal Classic Period occurred during an extended regional dry period, punctuated by more intense multiyear droughts centered at approximately 810, 860, and 910 A.D. These new data suggest that a century-scale decline in rainfall put a general strain on resources in the region, which was then exacerbated by abrupt drought events, contributing to the social stresses that led to the Maya demise., Paleoclimatologists have developed an increasingly precise record of climate change for the past few millennia, coveting the same span of time over which literate human societies developed. Until recently, archaeologists [...]

Previous investigations on laser-induced aerosols of brass samples showed that preferential vaporization of zinc occurs during the ablation process leading to elemental fractionation and limited possibilities for non matrix matched calibration. In a variety of experiments carried out within this study it is shown that multiple effects are complicating the quantification of brass using LA-ICPMS. It is shown that the ablated copper and zinc is not homogeneously distributed within the laser-produced aerosol. Copper was found enriched up to 100% in particles larger than 100 nm as shown from EDX measurements (electron excited) on individual particles, and zinc was enriched by over 40% in the particles smaller than the lowest measurable particle size (below 100 nm or in the vapor phase). Solution nebulization analysis on digested filter-collected aerosols results in a higher Cu/ Zn ratio than the certified value for the brass sample. ESEM pictures with analysis of the electron excited X-rays measured on the filter-collected material support the results showing copper enrichment. However, online LA-ICPMS measurements carried out under the same operating conditions as for filtering show a copper depletion within the ICP, which leads to the conclusion of partial vaporization and ionization of the aerosol particles in the ICP. The larger particles containing more or exclusively copper are not completely ionized. Within this study, three sources of elemental fractionation can be distinguished and described: (A) The ablation process leads to no measurable copper enrichment at the ablation crater rim. (B) Zinc deposition between the ablation site and the aerosol collection on filters leads to an up to 37% higher Cu/Zn ratio on the filter in comparison to the certified value. (C) On-line laser ablation aerosols measured within the ICPMS lead to significantly lower Cu/Zn ratios in comparison to the certified value. (D) Combination of the various studied sources of fractionation can finally lead to an agreement between measured and certified values due to inverse overlapping of various fractionation sources.

Niobium-92 ([sup.92]Nb) decays to zirconium-92 ([sup.92]Zr) with a half-life of 36 million years and can be used to place constraints on the site of p-process nucleosynthesis and the timing of early solar system processes. Recent results have suggested that the initial [sup.92]Nb/[sup.93]Nb of the solar system was high (> [10.sup.-3]). We report Nb-Zr internal isochrons for the ordinary chondrite Estacado (H6) and a clast of the mesosiderite Vaca Muerta, both of which define an initial [sup.92]Nb/ [sup.93]Nb ratio of ~[10.sup.-5]. Therefore, the solar system appears to have started with a ratio of, Some extinct radionuclides were sufficiently abundant at the start of the solar system that they produced variations in the abundance of their daughter isotopes in early-formed objects (1). Such nuclides [...]

A dynamic reaction cell (DRC) has been used to minimize the formation of metal-argide ions in inductively coupled plasma mass spectrometry and applied to the determination of Zr and Nb in Cr-rich samples. The formation of Ar[Cr.sup.+] species from the plasma gas and the sample matrix was reduced by ion molecule reactions inside a DRC of the ICPMS used. Hydrogen was used as reaction gas, and the efficiency in the reduction of Ar[Cr.sup.+] was similar to that of other plasma-based polyatomic ions as reported in an earlier study. The formation of Cr[O.sub.x.sup.+] ions is enhanced when the DRC is operated in pressurized mode. Adjustment of the transmission properties of the band-pass quadrupole to reject precursor ions can be achieved without dramatic decrease of sensitivity but with a significant improvement in the signal/background ratio. Measurements in solutions containing concentrations of up to 2 g/L Cr showed that the determination of Nb and Zr is possible in the nanogram per liter range in such a matrix. The limits of detection for Nb and Zr in pure Cr metal have been estimated at 2 ng/g for Nb and 5 ng/g for Zr. Analysis of basaltic reference samples resulted in very good agreement with previously published data.

Modal metasomatism in the Kaapvaal craton lithosphere is well documented in upper mantle xenoliths sampled by both group I (mainly late Cretaceous) and group II (mainly early Cretaceous to late Jurassic) kimberlites in the Kimberley area. The metasomatic style is characterized by introduction of K, H and large ion lithophile/high field strength (LIL/HFS) elements into the lithospheric mantle leading to the crystallization of hydrous potassic phases such as phlogopite and/or K-amphibole. Textures indicate that the hydrous phases either replace pre-existing assemblages in peridotites, forming the metasomatized peridotite suite (phlogopite-K-richterite-peridotites: PKPs) or crystallize from K-rich melts, forming the mica-amphibole-rutile-ilmenite-diopside (MARID) suite of xenoliths. These K-rich assemblages become potential low melting source components for alkaline incompatible trace element enriched magmas. The timing of metasomatism and its temporal and possible genetic relation to kimberlite magmatism is poorly constrained because of the rarity of phases in the metasomatic assemblages suitable for precise dating. Here we present precise sensitive high resolution ion microprobe (SHRIMP) U-Pb formation ages of 88 [+ or -] 2 (1[sigma] = 1 standard deviation) and 82 [+ or -] 3 Ma data for zircons from a K-richterite-phlogopite-bearing metasomatized peridotite (PKP) and a MARID xenolith respectively, sampled by a group I kimberlite. Both average PKP and MARID zircon ages are indistinguishable from emplacement ages of group I kimberlites in the Kimberley area dated at 83 [+ or -] 4 (2[sigma]) and 84 [+ or -] 0.9 Ma. One exceptionally old age spot of 102 [+ or -] 5 Ma from a PKP zircon provides evidence for modal metasomatism predating group I kimberlite emplacement by several millions of years with minor resetting of the U-Pb isotopic system of most analyzed PKP zircons to a group I emplacement age. Detailed textural and mineral chemical analysis, including high energy X-ray mapping and analysis of fluid inclusion daughter crystals, indicates a complex reaction history for both PKPs and MARIDs. U-Pb zircon ages from this study combined with literature data and experimentally derived models for MARID formation are used to suggest that MARID-formation is concurrent and genetically related to both group I and II kimberlite magmatism in the Kimberley area. MARID and PKP zircon ages are also consistent with the idea first proposed by Dawson and Smith (Geochim Cosmochim Acta 41: 309-323, 1977) that metasomatized peridotites may form from interaction of hydrous fluids expelled by solidifying MARID-type melts with peridotitic wall rocks.

Research on quartz crystals found in Mole Granite, Australia reveal information regarding post-entrapment changes regarding fluid inclusions. The authors find that these modifications can be attributed to deformation processes, and are more common in phenocrysts and vein quartz than free-standing crystals quartz.

Microbial mats collected at cold methane seeps in the Black Sea have carried out anaerobic oxidation of methane (AOM) to carbon dioxide by using sulfate as the electron acceptor. The more stable isomer is an isolation artifact generated under the acidic conditions needed for the isolation of the cofactors from the calcium carbonate-encrusted mats.

It is here established that potentiometric polymeric membrane electrodes based on electrically neutral ionophores are useful analytical tools for heavy metal ion determinations in drinking water at nanomolar total concentrations. This means that they can compete with the most sophisticated techniques of instrumental analysis. With optimized ion-selective membranes based on the lead-selective ionophore 4-tert-butylcalix[4]arenetetrakis(thioacetic acid dimethylamide) as model example, a number of native and spiked drinking water samples are potentiometrically assessed for lead, and the results compared with ICPMS measurements. The goal of this work is to demonstrate that detection limits in real world samples are routinely achieved that are, with 1.5 ppb, at least 10-fold lower than the lead action limit imposed by the U.S. Environmental Protection Agency (15 ppb). In contrast to earlier reports, different conditioning and measuring protocols are followed, and membranes and inner filling solution of optimized composition are used. The sensors are shown to be useful for the speciation analysis of lead in water as well. Typical water samples are acidified to pH 4 to assess total lead rather than free, uncomplexed lead. For lead concentrations above 2 ppb, the values compare very well with ICPMS. Main interferences are found to be [H.sup.+] and [Cu.sup.2+], although [Cu.sup.2+] only shows significant interference at levels around or above its own action limit (1.3 ppm), in which case the water sample would anyway show quality problems. An explicit, simplified flux model targeted to the practical use of these sensors explains the extent of expected interference. Sensors are shown to require a higher selectivity than predicted by models not considering ion fluxes, since in dilute samples, the counterdiffusion flux of lead from the membrane into the sample becomes potential determining. The model and experiments shown here are a foundation for future trace level applications of potentiometric polymeric membrane electrodes.

Experimental investigations in the system albite-water have been carried out to evaluate the accuracy of a new procedure to determine major-element solubilities in fluid phases and water solubilities in melts. The system albite-water had been examined previously and some consensus has been achieved with respect to phase relations, solidi, and water solubilities in the melts. Above 15 kbar the system approaches a second critical end point, where a distinction between fluid and melt no longer can be made and the term solidus has to be reconsidered. All experimental runs were carried out at near-solidus conditions at 5-17 kbar and 625-775 [degrees] C. Experimental charges contained albite, water, and a layer of diamond crystals (grain size 50 [micro]m). The pore space between the diamonds is preserved during the run indicating that the fluid was able to circulate throughout the entire capsule. During quenching, the material dissolved in the fluid precipitated between the diamond crystals and, as a result, could so be separated from the solid residue. The recovered capsules were directly embedded in epoxy and the diamond layers were analysed by laser ablation microprobe (LAM-ICP-MS). The new method allows the determination of a broad range of silicate/water ratios in aqueous fluids and hydrous melts. In some experimental runs at 15 and 17 kbar, fluids with approximately 40 wt% solute could be trapped leading to the conclusion that supercritical conditions were reached. Results furthermore indicate that albite dissolves non-stoichiometrically at 5 kbar producing a higher Na/Al and Si/Al in the solute than in the melt. Dissolution and melting at 10 kbar and higher pressures appears to be congruent within the limits of this method.

A Cenozoic record of hafnium isotopic compositions of central Pacific deep water has been obtained from two ferromanganese crusts. The crusts are separated by more than 3000 kilometers but display similar secular variations. Significant fluctuations in hafnium isotopic composition occurred in the Eocene and Oligocene, possibly related to direct advection from the Indian and At[antic oceans. Hafnium isotopic compositions have remained approximately uniform for the past 20 million years, probably reflecting increased isolation of the central Pacific. The mechanisms responsible for the increase in [sup.87]Sr/[sup.86]Sr in seawater through the Cenozoic apparently had no effect on central Pacific deep-water hafnium., Variations in the radiogenic isotope composition of seawater through time have the potential to provide information on changes in continental weathering, ocean floor hydrothermal activity, and ocean circulation (1-3) and [...]