Impact-induced hydrothermal dissolution in pyroxene: Petrographic and geochemical characterization of basalt-dominated polymict impact breccias from the Vargeão Dome, Brazil
- Autor(en)
- J. Epstein, Lidia Pittarello, Alvaro P. Crosta, Christian Koeberl
- Abstrakt
Constraints on impact-related hydrothermal alteration are important to enable the reconstruction of the possible processes affecting the surface of other terrestrial planets, such as Mars. Terrestrial impact structures excavated in basaltic targets provide the opportunity for analog studies. In Brazil, seven impact structures have been confirmed so far. Three of them, Vargeão Dome, Vista Alegre, and Cerro do Jarau, were formed in the same basaltic province belonging to the Paraná Basin, and they have several common characteristics. Oxidized basaltic breccias locally containing sandstone clasts occur in all these structures. In this work, selected samples of such breccias from the Vargeão Dome impact structure in southern Brazil were petrographically and geochemically investigated to further constrain the effects of the postimpact hydrothermal alteration. The breccia matrix shows typical oxidation effects induced by postimpact hydrothermal fluids, which highlight its heterogeneous nature, related to the impact event, and mixing components from different pre-impact stratigraphic formations. The detection of partially dissolved exsolution lamellae in pyroxene and of related alteration products constrains the effects of hydrothermal alteration in the basalts of the Vargeão Dome, which could serve as a terrestrial analog for planetary studies.
- Organisation(en)
- Department für Lithosphärenforschung
- Externe Organisation(en)
- Naturhistorisches Museum Wien (NHM), Universidade Estadual de Campinas, Universität Wien
- Journal
- Geological Society of America. Special Papers
- Band
- 550
- Seiten
- 537–549
- Anzahl der Seiten
- 13
- ISSN
- 0072-1077
- DOI
- https://doi.org/10.1130/2021.2550(24)
- Publikationsdatum
- 08-2021
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105105 Geochemie
- ASJC Scopus Sachgebiete
- Geology
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/78dc5dbc-1939-41c1-bce7-190fed1fdbb2