clinopyroxene; high-K magmatism; cation diffusion; shoshonites; mantel-petrogenesis; compositional zoning in pyroxene; magma differentiation
Fiedrich Alina M., Martin Lukas H. J., BachmannOlivier, Storck Julian-C., Ulmer Peter, Heinrich Christoph A. (2018), The influence of water in silicate melt on aluminium excess in plagioclase as a potential hygrometer, in Scientific Reports
, 8(1), 12421-12421.
Lierenfeld Matthias Bernhard, Zajacz Zoltán, Bachmann Olivier, Ulmer Peter (2018), Sulfur diffusion in dacitic melt at various oxidation states: Implications for volcanic degassing, in Geochimica et Cosmochimica Acta
, 226, 50-68.
Müntener Othmar, Ulmer Peter (2018), Arc crust formation and differentiation constrained by experimental petrology, in American Journal of Science
, 318(1), 64-89.
Ulmer Peter, Kaegi Ralf, Müntener Othmar (2018), Experimentally Derived Intermediate to Silica-rich Arc Magmas by Fractional and Equilibrium Crystallization at 1·0 GPa: an Evaluation of Phase Relationships, Compositions, Liquid Lines of Descent and Oxygen Fugacity, in Journal of Petrology
, 59(1), 11-58.
Wotzlaw Jörn-Frederik, Brack Peter, Storck Julian-Christopher (2018), High-resolution stratigraphy and zircon U–Pb geochronology of the Middle Triassic Buchenstein Formation (Dolomites, northern Italy): precession-forcing of hemipelagic carbonate sedimentation and calibration of the Anisian–Ladinian boundary interval, in Journal of the Geological Society
, 175(1), 71-85.
Müller Inigo A., Violay Marie E.S., Storck Julian-Christopher, Fernandez Alvaro, van Dijk Joep, Madonna Claudio, Bernasconi Stefano M. (2017), Clumped isotope fractionation during phosphoric acid digestion of carbonates at 70 °C, in Chemical Geology
, 449, 1-14.
Nandedkar Rohit H., Hürlimann Niklaus, Ulmer Peter, Müntener Othmar (2016), Amphibole–melt trace element partitioning of fractionating calc-alkaline magmas in the lower crust: an experimental study, in Contributions to Mineralogy and Petrology
, 171(8-9), 71-71.
Strock Julian-Christopher, Brack Peter, Wotzlaw Jörn-Frederik, Ulmer Peter, Timing and evolution of Middle Triassic magmatism in the Southern Alps (northern Italy), in Journal of the Geological Society
, online, 1-16.
This research proposal requesting funding for 2 PhD students for 36 months and addresses 2 different goals: Project A targets the petrogenesis and across crustal differentiation of shoshonitic magmas linked with a case study of the mid-Triassic magmatism in the Southern Alps. Project B is an ongoing project studying cation diffusion in clinopyroxene solid-solutions. Project A Shoshonitic magmatism in continental areas is extensively used as a geotectonic marker for specific environments and mantle sources, the most generally accepted is “subduction-related” metasomatism of subcontinental lithospheric mantle that becomes remobilized during subsequent tectonic events. There are widely different models proposed for their mantle sources and conditions of melt generation. Very limited information is available on the differentiation paths of such magmas ascending from mantle depth differentiating in crustal magma chambers on their way towards shallow levels. This prevents linking evident different geochemical trends observed in shoshonitic suites closely related in time and space with either variable source compositions/conditions of partial melting or variable differentiation trends controlled by the temperature-pressure-time evolution of the magmatic system. This experimental study targets two pertinent issues: (1) source composition and condition of partial melting by studying the high-pressure phase assemblages and conditions of multiple saturation of primary, mantle derived shoshonitic magmas under mantle conditions (1-3 GPa, 1100-1400°C); and (2) the influence of pressure and volatile content on the differentiation paths of primary and derivative shoshonitic magmas during their ascent from deep to middle crustal conditions (0.5-1.5 GPa, 800-1300°C). The investigation is linked to magmatic products of the short-lived mid-Triassic shoshonite activity in the Dolomites area of the Southern Alps (northern Italy) that provide a complete spectrum of plutonic and volcanic rocks from most primitive to highly evolved. Middle Triassic sediments and magmatic rocks in this area are currently among the best studied examples regarding the interplay of coeval tectonics, sedimentation and magmatic activity. Age and geochemical data provide tight constraints for a rigorous testing of experimental results which should also allow general conclusions to be drawn on the evolution of continental shoshonitic magmatism and its significance regarding tectonic environment.Project B is an ongoing experimental study (since 1.4.2013) determining the cation interdiffusion coefficients at low pressures under controlled oxygen fugacity in Ca-rich clinopyroxene solid solutions, a common igneous mineral characterized by slow cation diffusion kinetics. The experimental study combines established experimental techniques with state-of-the-art analytical methods (ATEM, FIB milling (both at EMEZ), secondary ion mass spectrometry, SIMS and NanoSIMS at the Lausanne (SwissSIMS consortium and EPFL respectively) to determine low cation diffusivities in pyroxenes. We employ the SOI (seed/overgrowth interdiffusion) technique to quantify cation interdiffusion along the diopside - CaAl2SiO6 (CaTs) and diopside - NaFe3+S2O6 (acmite) joins representing the most common clinopyroxene zoning patterns observed in igneous systems. This study provides crucial diffusivity data required for the modeling of zoning patterns in natural plutonic and volcanic rock samples in order to extract time durations and/or rates of processes such as magma differentiation, mixing/mingling, storage and transport ultimately controlling the fate of magmas passing through the Earth´s crust from their mantle sources to the volcanic edifices at the Earth´s surface. Clinopyroxenes are particularly useful to constrain long duration (100s to 1000s of years) processes and/or processes operating at slow rates in plutonic igneous environment within the Earth´s crust.