Geology and impact features of Vargeão Dome, southern Brazil

Autor(en)

Alvaro P. Crosta, César Kazzuo-Vieira, Lidia Pitarello, Christian Koeberl, Thomas Kenkmann

Abstrakt

Vargeão Dome (southern Brazil) is a circular feature formed in lava flows of the Lower Cretaceous Serra Geral Formation and in sandstones of the Paraná Basin. Even though its impact origin was already proposed in the 1980s, little information about its geological and impact features is available in the literature. The structure has a rim-rim diameter of approximately 12km and comprises several ring-like concentric features with multiple concentric lineaments. The presence of a central uplift is suggested by the occurrence of deformed sandstone strata of the Botucatu and Pirambóia formations. We present the morphological/structural characteristics of Vargeão Dome, characterize the different rock types that occur in its interior, mainly brecciated volcanic rocks (BVR) of the Serra Geral Formation, and discuss the deformation and shock features in the volcanic rocks and in sandstones. These features comprise shatter cones in sandstone and basalt, as well as planar microstructures in quartz. A geochemical comparison of the target rock equivalents from outside the structure with the shocked rocks from its interior shows that both the BVRs and the brecciated sandstone have a composition largely similar to that of the corresponding unshocked lithologies. No traces of meteoritic material have been found so far. The results confirm the impact origin of Vargeão Dome, making it one of the largest among the rare impact craters in basaltic targets known on Earth.

Organisation(en)

Department für Lithosphärenforschung

Externe Organisation(en)

Universidade Estadual de Campinas, Petróleo Brasileiro S.A, Naturhistorisches Museum Wien (NHM), Albert-Ludwigs-Universität Freiburg

Journal

Meteoritics and Planetary Science

Band

47

Seiten

51-71

Anzahl der Seiten

21

ISSN

1086-9379

DOI

https://doi.org/10.1111/j.1945-5100.2011.01312.x

Publikationsdatum

2012

Peer-reviewed

Ja

ÖFOS 2012

105101 Allgemeine Geologie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/abdbd0a1-c700-45de-8830-70146716f003