Melting and cataclastic features in shatter cones in basalt from the Vista Alegre impact structure, Brazil
- Autor(en)
- Lidia Pittarello, Fabrizio Nestola, Viti C., Alvaro P. Crosta, Christian Koeberl
- Abstrakt
Shatter cones are one of the most widely recognized pieces of evidence for meteorite impact events on Earth, but the process responsible for their formation is still debated. Evidence of melting on shatter cone surfaces has been rarely reported in the literature from terrestrial impact craters but has been recently observed in impact experiments. Although several models for shatter cones formation have been proposed, so far, no one can explain all the observed features. Shatter cones' from the Vista Alegre impact structure, Brazil, formed in fine-grained basalt of the Jurassic-Cretaceous Serra Geral Formation (Paraná large igneous province). A continuous quenched melt film, consisting of a crystalline phase, mica, and amorphous material, decorates the striated surface. Ultracataclasites, containing subrounded pyroxene clasts in an ultrafine-grained matrix, occur subparallel to the striated surface. Several techniques were applied to characterize the crystalline phase in the melt, including Raman spectroscopy and transmission electron microscopy. Results are not consistent with any known mineral, but they do suggest a possible rare or new type of clinopyroxene. This peculiar evidence of melting and cataclasis in relation with shatter cone surfaces is interpreted as the result of tensile fracturing at the tip of a fast propagating shock-induced rupture, which led to the formation of shatter cones at the tail of the shock front, likely during the early stage of the impact events.
- Organisation(en)
- Department für Lithosphärenforschung
- Externe Organisation(en)
- Università degli Studi di Padova, Universidade Estadual de Campinas, Università Degli Studi di Siena, Naturhistorisches Museum Wien (NHM)
- Journal
- Meteoritics and Planetary Science
- Band
- 50
- Seiten
- 1228-1243
- Anzahl der Seiten
- 16
- ISSN
- 1086-9379
- DOI
- https://doi.org/10.1111/maps.12466
- Publikationsdatum
- 07-2015
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105105 Geochemie
- ASJC Scopus Sachgebiete
- Geophysics, Space and Planetary Science
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/melting-and-cataclastic-features-in-shatter-cones-in-basalt-from-the-vista-alegre-impact-structure-brazil(284480ba-d570-437a-9086-9c799e86a2eb).html