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Re-equilibration processes in grain-internal domains: The interrelation of mineral reactions and deformation during metamorphism

2010-2015: Austrian Science Fund FWF I471-N19
International Joint Project in the framework of the DFG-FWF funded Research Group FOR741-DACH

Principal Investigators:
Gerlinde HABLER (University of Vienna, AUT)
Bernhard GRASEMANN (University of Vienna, AUT)
Rainer ABART (University of Vienna, AUT)

Predoctoral Researchers:
Thomas GRIFFITHS (University of Vienna, AUT)
Tobias EBERLEI (University of Vienna, AUT)
Anna ROGOWITZ (University of Vienna, AUT)
Elizaveta KOVALEVA (University of Vienna, AUT)

Cooperation Partners:
Stefan ZAEFFERER (MPIE Düsseldorf, DEU)
Dieter RHEDE (Helmholtz-Center GFZ Potsdam, DEU)
Richard WIRTH (Helmholtz-Center GFZ Potsdam, DEU)
Alexander PROYER (KFU Graz, AUT)
Petr SPACEK (Academy of Sciences/Masaryk University, CZE)
Martin THÖNI (University of Vienna, AUT)
Theodoros NTAFLOS (University of Vienna, AUT)
David SCHNEIDER (University of Ottawa, CAN)

 

Abstract: Mineral inclusions inside host crystals are widely used to infer information about evolution of rocks affected by changing conditions in the earth. Due to shielding by the host crystal, inclusions may retain information about relatively early events and conditions that may have been erased in the rock outside the host. However, information stored in inclusions can still be erased by adjustment of the inclusion properties in response to later events, a process called ‘re-equilibration’.
In the joint project “Nanoscale Processes and Geomaterials properties” we investigated relationships between host and inclusion crystals in different kinds of rocks, in order to understand how and under which circumstances information recorded by inclusions (e.g. their chemical and isotopic composition, their shapes and sizes, and the orientation of their crystal lattices) can be altered by re-equilibration. Special attention was paid to the feedbacks between the way host crystals had been deformed and alteration of the inclusion properties listed above. We found that knowing the behavior of a host crystal during deformation is important for understanding whether the inclusions within it have experienced re-equilibration, and that the effects of re-equilibration can help us to understand the timing of the deformation and the conditions at which it occurred.
Studying garnet crystals from deformed and altered igneous rocks in the Koralpe region of Austria, we found localized damage zones in the host crystal caused by cracking. Inclusions within these damaged zones adjusted their size and shape much faster than other inclusions according to changed conditions, even though the cracks themselves had sealed up before. This means that cracks in the host can have an important influence on the re-equilibration of nearby inclusions, even if they healed a long time ago.
Work carried out on samples from the Alps and Greece identified the specific types of deformation happening in the rocks studied and the effects of each type on chemistry and isotope ratios inside deformed crystals. Isotope ratios are used to date rocks, so future studies can use these results to test if their deformed samples can provide age-information and to identify samples where it may be possible to date the timing of deformation itself.
The orientation of the crystal lattices and shapes of inclusions relative to the orientation of the host crystal lattice has often been used to infer the origins of inclusions. Our study of crystallographic orientation relationships (CORs) in the Koralpe garnets revealed new, complex CORs, only detectable using large datasets. Unlike well-known “specific CORs”, which imply a fully fixed crystal orientation of the inclusions with respect to the host, “statistical CORs” allow for dispersion of inclusion orientations by rotation or clustering around host lattice directions. These CORs may have previously been overlooked, and with further research may provide new information on conditions during inclusion formation.

 

 

Publications (peer-reviewed):

Griffiths, T. A., Habler, G., Abart, R. (2016): Crystallographic orientation relationships in host–inclusion systems: new insights from large EBSD datasets American Mineralogist, 101, 690-705. DOI: 10.2138/am-2016-5442 (link to article)

Eberlei, T., Habler, G., Wegner, W., Schuster, R., Körner, W., Thöni, M., Abart, R. (2015): Rb/Sr isotopic and compositional retentivity of muscovite during deformation. Lithos, 227, 161-178. DOI: 10.1016/j.lithos.2015.04.007

Kovaleva, E., Klötzli, U., Habler, G., Wheeler, J. (2015): Planar microstructures in zircon from paleo-seismic zones. American Mineralogist, 100, 1834-1847. DOI: 10.2138/am-2015-5236 (link to preprint)

Pittarello, L., Habler, G., Abart, R., Rhede, D. (2015): Garnet growth in frictional melts of the Ivrea Zone (Italy). Italian Journal of Geosciences, 134, 149-161. DOI: 10.3301/IJG.2014.53 (link to preprint)

Rogowitz, A., Huet, B., Schneider, D., Grasemann, B. (2015): Influence of high strain rate deformation on 40Ar/39Ar mica ages from marble mylonites (Syros, Greece). Lithosphere, 7, 535-540. DOI: 10.1130/l455.1 (link to preprint)

Eberlei, T., Habler, G., Grasemann, B., Abart, R. (2014): Upper–greenschist facies intragrain deformation of albite in mylonitic meta–pegmatite and the influence of crystallographic anisotropy on microstructure formation. Journal of Structural Geology, 69, 47-58. DOI: 10.1016/j.jsg.2014.10.001 (link to preprint)

Griffiths, T. A., Habler, G., Rhede, D., Wirth, R., Ram, F., Abart, R. (2014): Localization of submicron inclusion re-equilibration at healed fractures in host garnet. Contributions to Mineralogy and Petrology, 168, 1077. DOI: 10.1007/s00410-014-1077-4 (link to preprint)

Jeřábek, P., Abart, R., Rybacki, E., Habler, G. (2014): Microstructure and texture evolution during growth of magnesio-aluminate spinel at corundum - periclase interfaces under uniaxial load: the effect of stress concentration on reaction progress. American Journal of Science, 314, 940-965. DOI: 10.2475/05.2014.02 (link to preprint)

Kovaleva, E., Klötzli, U., Habler, G., Libowitzky, E. (2014): Finite lattice distortion patterns in plastically deformed zircon grains. Solid Earth, 5, 1099-1122. DOI: 10.5194/se-5-1099-2014

Rogowitz, A., Grasemann, B., Huet, B., Habler, G. (2014): Strain rate dependent calcite microfabric evolution – An experiment carried out by nature. Journal of Structural Geology, 69, 1-17. DOI: 10.1016/j.jsg.2014.08.004 (link to preprint)

Proyer, A., Habler, G., Abart, R., Wirth, R., Krenn, K., Hoinkes, G. (2013): TiO2 exsolution from garnet by open-system precipitation: evidence from crystallographic and shape preferred orientation of rutile inclusions. Contributions to Mineralogy and Petrology, 166, 211-234. DOI: 10.1007/s00410-013-0872-7 (link to preprint)

Špaček, P., Ackerman, L., Habler, G., Abart, R., Ulrych, J. (2013): Garnet Breakdown, Symplectite Formation and Melting in Basanite-hosted Peridotite Xenoliths from Zinst (Bavaria, Bohemian Massif). Journal of Petrology, 54, 1691-1723. DOI: 10.1093/petrology/egt028 (link to preprint)

Ettler, V., Zdenek, J., Vítková, M., Skála, R., Kotrlý, M., Habler, G., Klementová, M. (2012): Reliability of chemical microanalyses for solid waste materials. Journal of Hazardous Materials, 221-222, 298-302. DOI: 10.1016/j.jhazmat.2012.04.015 (link to preprint)

Tajcmanová, L., Abart, R., Wirth, R., Habler, G., Rhede, D. (2012): Intracrystalline microstructures in alkali feldspars from fluid-deficient felsic granulites: a mineral chemical and TEM study. Contributions to Mineralogy and Petrology, 164, 715-729. DOI: 10.1007/s00410-012-0772-2 (link to preprint)

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