metamorphic rocks; Alps; hydrothermal systems; fluid chemistry; LA-ICP-MS; thermodynamic modeling; fluid-rock interaction; reactive transport; geochronology
Wagner Thomas, Fusswinkel Tobias, Wälle Markus, Heinrich Christoph (2016), Microanalysis of fluid inclusions in crustal hydrothermal systems using laser ablation methods, in Elements
, 12, 323-328.
Lanari P., Wagner T., Vidal O. (2014), A thermodynamic model for di-trioctahedral chlorite from experimental and natural data in the system MgO-FeO-Al2O3-SiO2-H2O. Applications to P-T sections and geothermometry., in Contributions to Mineralogy and Petrology
, 167(2), 968.
Rauchenstein-Martinek Klara, Wagner Thomas, Wälle Markus, Heinrich Christoph (2014), Gold concentrations in metamorphic fluids: a LA-ICPMS study of fluid inclusions from the Alpine orogenic belt, in Chemical Geology
, 385, 70-83.
Rauchenstein-Martinek Klara, Wagner Thomas, Wälle Markus, Heinrich Christoph, Arlt Thilo, Chemical evolution of metamorphic fluids in the Central Alps, Switzerland: Insight from LA-ICPMS analysis of fluid inclusions, in Geofluids
This proposal is for an integrated PhD project to study the fluid chemistry and fluid-rock interaction processes of Alpine fissure quartz veins, Central Alps, Switzerland. Metamorphic veins are one of the most important sources of information about fluid flow and fluid-rock interaction during orogenic processes and have been extensively studied from a structural, fluid inclusion and stable isotope perspective. It has been established that vein formation takes place in a continuum between fluid- and rock-buffered environments. Previous studies of the Alpine quartz veins along a geotraverse in the Central Alps have documented the mineral assemblages, fluid inclusion characteristics and stable isotope relationships. Based on the results of these studies, it was concluded that the Alpine veins have formed at the transition between final collision and exhumation and uplift of the Alps, and that the fluid systems have evolved under essentially rock-buffered conditions that approach local fluid-rock equilibrium. Despite the considerable work done, several important questions remain open, such as the chemical composition (solute inventory) of the fluids, the differences in solute content between aqueous and aqueous-carbonic fluids, the chemical similarities between typical metamorphic fluids such as those found in the Alpine quartz veins and ore fluids responsible for gold mineralization, the precise geochronological age of the Alpine quartz veins, the lifetime of the fluid systems involved, and the relative importance of advective and diffusive processes in fluid-rock interaction and mineralization. The proposed project will address these questions through an integrated study that will combine field and petrographic work, fluid inclusion analysis, geochronology and rigorous numerical modeling of geochemical fluid-mineral reaction. The work program will include the following tasks: (1) Generating a structural framework for the Alpine quartz veins from selected localities showing relationships of ductile deformation, faults and possibly multiple generations of massive and open veins. (2) Obtaining a comprehensive data set of the fluid chemistry of different fluid inclusion generations and assemblages preserved in the Alpine quartz veins (with emphasis on the differences between aqueous and aqueous-carbonic fluids) using LA-ICP-MS analysis of single fluid inclusions. (3) Generating new geochronological data for selected Alpine veins to constrain more precisely the formation age and the lifetime of the fluid systems. (4) Test the model that the Alpine quartz veins formed under rock-buffered conditions where diffusion processes were dominant, through novel numerical geochemical modeling. The results from the proposed study will significantly contribute to the understanding of the relative importance and scales of different mass transfer mechanisms in vein formation and metamorphic fluid flow in the upper crust.