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88. Jahrestagung 88Th Annual Meeting Wissenschaftliches Programm • Sontag, 19.9.2010 FROM DUST TO DUST 88. JAHRESTAGUNG der Deutschen Mineralogischen Gesellschaft 88th ANNUAL MEETING of the German Mineralogical Society 19.–22. September 2010 •1 Münster Abstracts Table of Content PLENARY TALKS 4 GOLDSCHMIDT LECTURE 8 S 01: Early differentiation and core formation of the terrestrial planets Oral Presentations 11 Poster Presentations 215 S 02: Functional materials, Archaeometry Oral Presentations 22 Poster Presentations 221 S 03: Metamorphic processes Oral Presentations 33 Poster Presentations 228 S 04: CO2 sequestration into geological reservoirs and laboratory Oral Presentations 43 Poster Presentations 235 S 05: Early solar system Oral Presentations 55 Poster Presentations 258 S 06: Experimental and theoretical petrology Oral Presentations 77 Poster Presentations 267 S 07: General and applied crystallography Oral Presentations 87 Poster Presentations 281 S 08: Subduction zone processes Oral Presentations 105 Poster Presentations 303 S 09: Environmental mineralogy and geochemistry Oral Presentations 112 Poster Presentations 308 S 10: Mineralogy of the deep earth Oral Presentations 125 Poster Presentations 316 S 11: Fluid-rock and fluid-mineral interaction Oral Presentations 132 Poster Presentations 321 S 12: Geochemical signatures in environmental archives: Formation, preservation and application Oral Presentations 149 Poster Presentations 330 2 S 13: Ion Microprobe characterization of geo-materials Oral Presentations 163 Poster Presentations 349 S 14: Magmatic processes Oral Presentations 170 Poster Presentations 358 S 15: Time constraints on geological processes Oral Presentations 202 Poster Presentations 365 AUTHOR INDEX 367 3 PLENARY TALKS 4 Mineralogical Evolution of Meteorites Timothy J. McCoy (presenting author)1 1Dept. of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560-0119 USA. In a provocative paper, Hazen et al. (2008) argued that the mineralogy of terrestrial planets evolves as a consequence of a range of physical, chemical and biological processes. From an initial inventory of approximately a dozen currently-known presolar minerals, processes including melting in the solar nebula, impact, melting and differentiation, plate tectonics, metamorphism, evaporation, atmospheric oxidation, and the rise of life produced the ~4300 mineral known today. Examining mineralogy in the light of planetary evolution introduces geologic time to the study of, and teaching of, this fundamental geological discipline. In this abstract, I explore the earliest stages of such evolution, examining how the mineralogy recorded in meteorites tracks this diversification and questioning whether such a diversification is, in fact, linear. The earliest mineral record dates from before the formation of our own Solar System. Presolar grains formed in a previous generation of stars seeded the solar nebula. First inferred from noble gas anomalies, acid dissolution and physical separation led to the identification of the carbon-bearing phases diamond, silicon carbide and graphite. In situ studies have subsequently identified nitrides, carbides, oxides and silicates. Among the most active areas of meteorite research, the inventory of minerals, including the identification of new minerals and the recognition of abundant amorphous materials, is likely to grow dramatically in the coming decade. Condensation during cooling of the solar nebula produced the precursors of calcium-aluminum-inclusions (CAIs) and chondrules which were subsequently remelted by transient heating events. Composed of refractory oxides and silicates, the minerals found in CAI’s sample all the crystal systems. Magnesian silicates dominate primitive, chondritic meteorites but are joined by a range of sulfides, oxides, carbides, silicides, and phosphides that reflect the oxygen fugacity under which the meteorites formed. The accretion of chondritic components into km-sized asteroids initiated thermal and aqueous alteration, as well as leading to a dynamic impact environment. Within these asteroids, melting of ice produced phyllosilicates, oxides, carbonates, sulfates and halides. Thermal metamorphism produced albitic plagioclase and may have been responsible for the formation of phosphates, silica polymorphs, sinoite (Si2N2O), amphibole and others. Shock metamorphism transformed olivine into ringwoodite and wadsleyite, while pyroxene, ilmenite and SiO2 all suffered similar fates. The onset of melting first created additional diversity with S,C,P-rich metallic melts reacting to form Na-Ca-Mg phosphates and carbides. At this point, the seemingly unending increase in mineralogical diversity essentially reversed itself, as near-total melting produced a molten planet that may have only had olivine as a residual, solid mineral phase. However, separation into core, mantle and crust gave rise to a new set of minerals, with new silicates and oxides forming in the crust as a result of fractional crystallization and Fe,Ni, phosphide, nitride, sulfide and phosphate phases appearing in the core. Absent from Earth, some meteoritic minerals were formed in environments that would never be repeated. A more remarkable feature is that many meteoritic minerals formed from processes – aqueous alteration, metamorphism, igneous differentiation – that formed and would continue to form many of the diverse minerals found on Earth. Reference: Hazen, R.M. et al. (2008) Mineral evolution. American Mineralogist 93, 1693-1720. 5 Oceanic floor basalts - a view of mantle processes and mantle history from the experimental study of phase relations and trace-element distributions Hugh O’Neill1, Xi Liu2 and Frances Jenner3 1Research School of Earth, The Australian National University, Canberra ACT, Australia 2Now at: School of Earth and Space Sciences, Peking University, Beijing 100871, P. R. China 3Now at: Institute for Study of the Earth's Interior, Okayama University at Misasa, Yamada 827, Misasa, Tottori 682-0193, Japan. The processes leading to the production of ocean-floor basalts (OFBs) by passive upwelling at mid-ocean ridges and other spreading centres are now considered to be reasonably well understood, but many interesting questions remain, such as what the variations in chemical composition of OFBs reveal about the physical conditions of melting, as opposed to chemical inhomogeneity in the mantle. The phase equilibrium relations of partial melting of peridotitic mantle can be parameterized starting with a four- component system, the components being SiO2, AlO1.5, CaO and MO, where M stands for Mg and Fe2+. Partial melting of upper mantle peridotite involves five phases, namely melt plus four solid phases: olivine, orthopyroxene, clinopyroxene, and an aluminous phase – plagioclase, spinel or garnet, depending on pressure. With five phases and four components, partial melting is thermodynamically univariant, so melt compositions and melting temperatures can be rigorously parameterized as a function of pressure without specifying the compositions of the solid phases. The isobaric invariance of the system is maintained if the concentration of each minor component added to the system is specified in just one phase. Hence the parameterization can be extended to natural composition using the concentrations of Na2O, TiO2, K2O, P2O5, H2O and CO2 in the melt, all of which components are concentrated in the melt during partial melting. The effect of varying Mg/Fe2+ in the system can also be explicitly accounted for using this ratio in the melt; importantly, it has only a minor influence. The only significant compositional variable that cannot be accounted for adequately by its concentration in the melt is Cr, because of its highly compatible nature. Cr is important because Cr-Al solid solutions in the solid phases determine the activity of Al2O3 in the melt. The effect of Cr is parameterized using the molar Cr/(Al+Cr) (i.e., the Cr#) in spinel. Hence the parameterization is at present limited to melting in the spinel-lherzolite facies. Calibration of the parameterization utilizes the extensive experimental database in the literature on multiply saturated melting in both simple and complex (“natural”) systems from 0 to 3.0 GPa. This database now comprises over 200 experiments. We have applied the parameterization to analyses of mid-ocean ridge basaltic glasses from active spreading centres that are sufficiently primitive to have crystallized only olivine (± minor chromite) at low pressure, to infer for each glass: 1) its pressure of partial melting, assuming batch melting; 2) the Cr# of residual spinel; and 3) the extent of subsequent olivine fractionation. Unlike other petrologic methods aimed at obtaining the pressure of origin of oceanic basalts, no assumption needs to be made about the composition of the source mantle, nor does the calculated extent of olivine fractionation depend on assumptions about Mg-Fe partitioning. The calculated melting pressure of the glasses correlates well with the depth of water over the mid-ocean ridge from which it was sampled. However, variations in mantle potential temperatures are calculated to be small, suggesting that the variations in melting pressure may be due to cessation of melting due to heat loss by conduction to the surface. The concentrations of 66 elements have been determined by electron microprobe and laser-ablation ICP-MS in 340 ocean floor basaltic glasses from the Smithsonian collection (Melson et al. 2002). The statistical distributions of K, P and
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