compositional zoning in pyroxene; clinopyroxene; crystal- and bubble-bearing magmas; experimental rock deformation; elastic properties; magma rheology; cation diffusion
Tripoli Barbara, Cordonnier Bennoit, Zappone Alba, Ulmer Peter (2016), Effects of crystallization and bubble nucleation on the seismic properties of magmas, in Geochemistry, Geophysics, Geosystems (G3)
, 17, 602-615.
Lierenfeld M.B., Zajacz Z., Bachmann O., Ulmer P. (2016), The effects of oxygen fugacity on sulfur diffusion in dacite melts., in Goldschmidt Conference Abstracts
Weidendörfer Daniel, Mattsson Hannes, Ulmer Peter (2014), Dynamics of magma mixing in partially crystallized magma chambers: textural and petrological constraints from the basal complex of the Austurhorn intrusion (SE Iceland), in Journal of Petrology
, 55, 1865-1903.
Tripoli barbara, Cordonnier Benoit, Ulmer Peter (2013), Effects of crystallization and bubble nucleation on the seismic properties of magmas, in 11th Swiss Geoscience Meeting, Abstracts
, 11, P2.7.
Pistone Mattia, Caricchi Luca, Ulmer Peter, Reusser Eric, Ardia Paola (2013), Rheology of volatile-bearing crystal mushes: Mobilization vs. viscous death, in Chemical Geology
, 345, 16-39.
Tripoli Barbara, Cordonnier Benoit, Ulmer Peter (2013), Seismic properties of magmatic processes at laboratory scale: Effects of crystallization and bubble nucleation, in Geophysical Research Abstracts
, 16, EGU2014-74.
Madonna Claudio, Quintal Beatriz, Frehner Marcel, Almqvist Bjarne S.G., Tisato Nicola, Pistone Mattia, Marone Frederica, Saenger Erik H. (2013), Synchrotron-based X-ray tomographic microscopy for rock physics investigations, in Geophysics
, 80(1), D53-D64.
This research project is a continuation project merging ongoing projects 200021_125464 / 1 (12 month April 2011-March 2012) and 200020-120221 (24 months until September 2012). The continuation projects request funding for 2 PhD students for 36 and 30 months respectively and addresses 2 different goals: project A is the continuation of project 200021_125464 / 1 aimed at determining rheologic (viscosity) and elastic (seismic wave propagation velocities) properties of synthetic crystal-liquid-bubble bearing magmas; project B is the continuation of project 200020-120221 with a new PhD student studying cation diffusion in clinopyroxene solid-solutions. Project A investigates rheologic and elastic behavior and properties of intermediate composition (andesitic to trachytic) calc-alkaline magmas containing feldspar crystals and vapor bubbles. Such magmas span a wide range of eruptive style, from effusive flows to devastating explosive Plinian eruptions. This dynamic variety of volcanic unrest is a direct consequence of the underground driving forces, the magma rheological properties, and the complex feed-backs between them. To quantify this phenomenon, we propose continuation of the ongoing experimental investigation of the mechanical properties of crystal and bubble-bearing magmas of the hereto poorly constrained andesite and trachyte compositions using a Paterson-type internally-heated gas-pressure apparatus. The viscosity, shear strength, and elastic parameters are characterized over a broad range of extrinsic conditions (temperature, confining pressure and differential stress) and intrinsic rock properties (crystal fraction, bubble fraction and melt composition) relevant for crystal-rich, evolved magma compositions. The study consists of a rock-deformation investigation employing plagioclase, the predominant crystal phase in andesite and trachyte enabling us to quantify crystal-related effects on magma rheology such as crystal shape and crystal strength. Experiments on bubble-bearing samples are performed to constrain their impact on magma rheology. These experiments will provide the basis, for the first time, for realistic flow laws for a given melt-crystal-bubble relationship. The investigation of the ductile-brittle transition will be achieved by approaching the critical relaxation state by two different ways: (1) by lowering the temperature and (2) by increasing the strain rate. Throughout all experiments, Acoustic Emission (AE) monitoring will be employed to determine the switch from ductile to brittle and vice versa, as well as monitoring decompression effects (i.e. bubble growth, bubble coalescence and degassing) during experiments on the bubble bearing samples. Project B is an experimental study aiming at the determination of 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, new SwissSIMS at Lausanne) to determine low cation diffusivities in pyroxenes. We propose to 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 will provide 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.