HR: 14:05h
AN: V43E-02    [Abstracts]
TI: Cathodoluminescence (CL) Petrography of UHP-metamorphic Rocks: New Avenues for Petrological Applications
AU: * Schertl, H
EM: hans-peter.schertl@rub.de
AF: Institut fuer Geologie, Mineralogie und Geophsik, Ruhr-Universitaet Bochum, Bochum, 44780, Germany
AU: Neuser, R
EM: rolf.neuser@rub.de
AF: Institut fuer Geologie, Mineralogie und Geophsik, Ruhr-Universitaet Bochum, Bochum, 44780, Germany
AB: Since the first application of CL microscopy on rock samples (Sippel, 1965; Marfunin, 1979), this technique has become a standard tool in mineralogy. First CL-studies, however, have mainly focused on sedimentary rocks and on zircon-zonations connected with ion probe dating. Here, we would like demonstrate the great advantages of a hot cathode CL microscope applied to UHP metamorphic rocks, in particular in conjunction with electronmicroprobe (EMP)-studies. The compilation of data presented include samples from Dora Maira/Italy, Kokchetav/Kazakhstan, Sulu/China, Western Gneiss region/Norway and Pohorje/Slovenia. Colored images of important but otherwise invisible growth features and internal structures of minerals, like small-scale growth zoning, inhomogeneities, exsolution lamellae, dissolution and deformational effects etc. can be easily achieved within seconds. Examples shown are oscillatory zoning patterns of garnet and kyanite, change of morphology during growth, regular and irregular zoning patterns of garnet, jadeite, omphacite, carbonates, clinopyroxene (partly with cracking/annealing structures), exsolution textures (dolomite/Mg-calcite; K-feldspar/pyroxene), different CL-colours of SiO₂-phases (coesite: bluish- green, quartz: dark red to violet, chalcedony: yellow), and special features of accessory minerals like zircon, diamond, apatite, and bearthite. Although being mainly descriptive, the conclusions drawn open new avenues for petrological applications. The knowledge of detailed structural characteristics of rock-forming minerals has an invaluable impact on the more precise and detailed derivation of PT-paths and thus on the evolution of geodynamic processes with any metamorphic rocks involved. Thus we propose the CL-technique to be used more intensively for routine investigations of thin sections as a pathfinder prior to chemical characterization by EMP.
DE: 3600 MINERALOGY AND PETROLOGY
DE: 3625 Petrography, microstructures, and textures
DE: 3652 Pressure-temperature-time paths
DE: 3654 Ultra-high pressure metamorphism
DE: 3900 MINERAL PHYSICS
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting