Goldschmidt2013 Conference Abstracts 2297 Compacted Nanoparticles for Evaporation behavior of forsterite Quantification in LA-ICPMS (Mg2SiO4) in a H2O-H2 gas DANIEL TABERSKY1, NORMAN LUECHINGER2, SAMUEL S. TACHIBANA1* AND A. TAKIGAWA2 2 2 1 , HALIM , MICHAEL ROSSIER AND DETLEF GÜNTHER * 1 Department of Natural History Sciences, Hokkaido 1ETH Zurich, Department of Chemistry and Applied University, N10 W8, Sapporo 060-0810, Japan. Biosciences, Laboratory of Inorganic Chemistry (*correspondence: [email protected]) (*correspondence: [email protected]) 2Carnegie Institution of Washington, Department of Terrestrial 2Nanograde, Staefa, Switzerland Magnetism, 5241 Broad Branch Road NW, Washington DC, 20015 USA. Gray et al. did first studies of LA-ICPMS in 1985 [1]. Ever since, extensive research has been performed to Forsterite (Mg2SiO4) is one of the most abundant overcome the problem of so-called “non-stoichiometric crystalline silicates in extraterrestrial materials and in sampling” and/or analysis, the origins of which are commonly circumstellar environments, and its evaporation behavior has referred to as elemental fractionation (EF). EF mainly consists been intensively studied in vacuum and in the presence of of laser-, transport- and ICP-induced effects, and often results low-pressure hydrogen gas [e.g., 1-4]. It has been known that in inaccurate analyses as pointed out in, e.g. references [2,3]. the evaporation rate of forsterite is controlled by a A major problem that has to be addressed is the lack of thermodynamic driving force (i.e., equilibrium vapor reference materials. Though the glass series of NIST SRM 61x pressure), and the evaporation rate increases linearly with 1/2 have been the most commonly reference material used in LA- pH2 in the presence of hydrogen gas due to the increase of ICPMS, heterogeneities have been reported for some sample the equilibrium vapor pressure. The deviation of the actual charges [4,5]. In addition, geological relevant elements such as evaporation rate from the ideal evaporation rate, which is Ti, Fe and Mg are present in very low concentrations only and given by an equilibrium vapor pressure and the kinetic theory thus not well suited for calibration. Elements such as Rh, Ru, of gases, is expressed as an evaporation coefficient (=Actual Pd, Pt and Au (PGEs) are either absent or present in very low rate/Ideal rate) ranging from 0 to 1 (a measure of kinetic concentrations. hindrance for evaporation). The evaporation coefficient is The production procedure of glass limits the 0.1-0.01 for evaporation of forsterite in vacuum and in implementation of these elements into the glass matrix at hydrogen gas depending on temperature and crystallographic concentrations required for many applications. Therefore, orientation of the evaporating surface [e.g., 1-4]. Besides the alternative methods for the production of calibrants were free-evaporation dominated regime [FED] (evaporation in studied concerning the implementation of PGEs into Silicates, vacuum) and the hydrogen-reaction dominated regime [HRD] Carbonates, and Iron-Sulfides, which are homogeneous at the (evaporation in hydrogen gas), Tsuchiyama et al. [5] proposed spatial resolution commonly used in microbeam techniques. another evaporation regime called H2O/H2 buffer-dominated Flame synthesis was used to reproduce the NIST 610 regime [HBD] as a dominant evaporation regime for forsterite matrix at similar concentrations. Furthermore, PGEs and other in protoplanetary disks at temperatures of <1400 K and under elements were added to the matrix. The resulting powder H2O-rich conditions. In the HBD regime, the equilibrium 1/2 consists of nanoparticles in the size range of 20-50 nm, which vapor pressure of forsterite is not controlled by pH2 , but by is well below the commonly crater diameters used in LA- the H2O/H2 ratio in the ambient gas. In spite of its potential ICPMS. The PGE concentration is for most of the elements importance, no experimental study has been done to around 500 mg/kg. Multiple analyses of these powders investigate the evaporation kinetics in the HBD regime. We provide a RSD for PGEs in the order of 1-3 %. have performed evaporation experiments on forsterite at low The difference between the pressed powder analysis and pressures with controlled H2O/H2 ratios, and have found that calcinated pellets shows indistinguishable results for most of the evaporation rates are controlled by the H2O/H2 ratio as the elements. The setup of production, preliminary results and proposed by [5] and that the evaporation coefficient is first figures of merit will be discussed. consistent with that in FED and HRD regimes. [1] A.L.Gray (1985), Analyst, 111, 551. [2] J. Pisonero et al. [1] Hashimoto (1983) Nature 347, 53-55. [2] Nagahara and (2009) J Anal Atom Spectrom, 24, 1145. [3] J. Koch and D. Ozawa (1996) GCA 60, 1445-1459. [3] Tsuchiyama et al. Günther (2009) Appl Sectrosc, 65, 155. [4] P. Sylvester and (1998) Mineral J. 20, 113-126. [4] Takigawa et al. (2009) S.M. Eggins (1997) Geostandard Newslett, 21, 215. [5] S.M. ApJ. 707, L97-L101. [5] Tsuchiyama et al. (1999) GCA 63, Eggins and J.M.G. Shelley (2002), Geostand Geoanal Res, 26, 2451-2466. 269 www.minersoc.org DOI:10.1180/minmag.2013.077.5.20 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/77/5/2297/2920875/gsminmag.77.5.20-T.pdf by guest on 30 September 2021 2298 Goldschmidt2013 Conference Abstracts Southern Hemisphere orbital forcing CO3, OH, and halogen microanalysis and its effects on CO2 and tropical in apatite group minerals Pacific climate R. CHRIS TACKER1 K. TACHIKAWA1, A. TIMMERMANN2, L. VIDAL1, 1North Carolina Museum of Natural Sciences, 11 W. Jones C. SONZOGNI1 AND O. ELISON TIMM2 St., Raleigh, NC, USA 27601-1029, 1 [email protected] Aix-Marseille Université, UMR7330, CNRS, IRD, CEREGE UM34,13545 Aix en Provence, France, [email protected] 2 The last three years have seen a re-evaluation of IPRC, SOEST, University of Hawaii, Honolulu, HI 96822, microanalytical methods for apatite, including standards. This USA presentation presents new data and reviews recent results for analytical methodology for C, OH, and halogens for apatite The western Pacific warm pool (WPWP) is an important minerals. heat source for the atmospheric circulation and influences Initial documentation of anisotropic beam-driven halogen climate conditions worldwide. Understanding its sensitivity to diffusion [1] in apatites, long ignored, has been confirmed and past radiative perturbations may help better contextualize the shown to be more complex for varying F and Cl magnitudes and patterns of current and projected tropical concentrations [2]. Quantitative analysis requires constraints climate change. Here we present a new Mg/Ca-based sea on crystal orientation for both unknowns and standards, as surface temperature (SST) reconstruction over the past 400 well as controlled history under the electron beam. Analytical kyr from the Bismarck Sea, off Papua New Guinea, along with methods presented here use accelerating voltages <10keV and results from a transient earth system model simulation. Our short analytical durations to clearly define the rise and fall in results document the primary influence of CO forcing on 2 count rates for zero-time regression. Data in hand show that F glacial/interglacial WPWP SSTs and secondary effects due to and Cl are rapidly lost from the apatite during analysis at 15 changes in wind-driven tropical boundary currents. In addition and 20 keV in all crystal orientations. Analyses are unlikely to to the SST, deep ocean temperature reconstructions from this be valid without regression-to-zero techniques for unknown core are linked with Southern Ocean temperature and sea-ice and standard. Uncertainties in electron microprobe halogen variations on timescales of ~23 kyr. It is proposed that analyses are magnified in OH caclulated by the difference Southern Hemisphere insolation changes serve as pacemaker method. for sea-ice variations in the Southern Ocean, which in turn Problems with FTIR analysis of apatite (strongly polarized modulate windstress curl-driven upwelling of carbon-rich OH stretching, crystal size, sample thickness) have been waters, hence controlling atmospheric CO and tropical 2 overcome to allow analysis of unpolished mineral separates WPWP temperatures. and experimental products. Polarized radiation is preferred for OH analysis, but unpolarized radiation can be used on (100) sections [3] and euhedral synthetic crystals. The A and B type carbonate substitutions are not strongly polarized, allowing use of unpolarized radiation. Carbonate and OH standards for apatite are lacking. A large FTIR dataset for naturally occurring apatites shows homogeneities or complexities precluding their use as standards. For example, Durango fluorapatite shows trimodal OH distribution (n=5570). Synthetic standards are under development. Previously published apatite studies should be carefully evaluated in the light of these results. [1] Stormer et al. (1993) Am. Miner.78, 641-648. [2] Goldoff et al. (2012) Am. Miner. 97, 1103–1115. [3] Tacker (2004) Am. Miner. 89, 1411-1421. www.minersoc.org DOI:10.1180/minmag.2013.077.5.20 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/77/5/2297/2920875/gsminmag.77.5.20-T.pdf by guest on 30 September 2021 Goldschmidt2013 Conference Abstracts 2299 Thermochronological investigation of Geobotany and biogeochemistry of seismogenic fault zones: an overview Sungun Copper deposit, northern and examples from Japanese Islands Iran: An implication to mineral TAKAHIRO TAGAMI 1 exploration 1 Division of Earth and Planetary Sciences, Graduate School B. TAGHIPOUR1 AND M. HEMMATI1 of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, 1Department of Earth Sciences, Shiraz University, Shiraz, Iran Japan. [email protected] ([email protected]) The timing of faulting episodes can be constrained by Sungun porphyry copper deposit is located in the east of radiometric dating of fault-zone rocks. Fault-zone material Azarbaidjan, NW of Iran. Geobotany is one of the important suitable for dating is produced by tectonic processes, such as methods in mineral exploration.