Hidas Károly online előadása, október 26. Regisztrálni kell! Seeing the unseeable: visualization of microstructures from ice to subduction zones


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Hidas Károly
A Spanyol Geológiai és Bányászati Intézet (Instituto Geológico y Minero de España) kutatójának előadására:

Seeing the unseeable: visualization of microstructures from ice to subduction zones

Helyszín: Zoom.
Időpont: 2020. október 26. 17.00
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Seeing the unseeable: visualization of microstructures from ice to subduction zones

Károly Hidas

Departamento de Investigación y Prospectiva Geocientífica (Department of Geoscientific Research and Prospective), Instituto Geológico y Minero de España (IGME; Geological and Mining Institute of Spain), Tres Cantos (Madrid), Spain

Based on a collaborative work with Fabrice Barou, Thomas Chauve, Nicole Dilissen, Carlos J. Garrido, Wolf-Achim Kahl, Vicente López Sánchez-Vizcaíno, David Mainprice, Maurine Montagnat, José Alberto Padrón-Navarta, Andréa Tommasi and many others.

With the advance and wide(r)-spread availability of novel analytical techniques, imaging and quantitative analysis of microstructure of geological materials is becoming a standard in many petrological studies. One of the techniques, which has gained increasing popularity in this field during the past decade, is the electron backscatter diffraction (EBSD). By now, this technique not only allows for the routine analysis of complicated rock microstructures, but it is also possible to carry out in-situ and semi in-situ experiments in the sample chamber on materials that behave analogous to major constituent minerals of the deep Earth interior. With this latter approach, the temporal evolution of microstructures can now be addressed, which is crucial for the better understanding of processes that occur at the grain scale in geological materials during deformation or annealing. On the other hand, in addition to the need for advanced microstructural analysis of 2-D thin sections, there is also an increasing demand for the reconstruction of microstructure in the rock volume. Representative 3-D microstructure of large geological samples composed of mm to cm-sized grains, however, is limited by currently available analytical techniques. X-ray micro computed tomography (µ-CT) is a powerful tool for imaging relatively large sample volumes with sufficient resolution but it does not allow for crystal orientation information, whereas EBSD provides quantitative microstructural data that is often difficult to translate into 3-D. Serial sectioning techniques combined with EBSD produce real 3-D microstructural data but they are destructive methods with very restricted available sample volume (max. 10-6 cm3).
In this contribution, I will show case studies that cover (i) the visualization of microstructural evolution of polycrystalline ice as an analog to that of anisotropic minerals in the deep lithosphere, and (ii) the reconstruction of 3-D microstructure by semi-destructive combination of µ-CT and EBSD in a coarse-grained rock sequence that formed by the high-pressure dehydration of antigorite serpentinite in a fossil subduction zone.