Geology and impact features of Vargeao Dome, southern Brazil

Autor(es)

Crosta, Alvaro P. ^[1] ; Kazzuo-Vieira, Cesar ^[2] ; Pitarello, Lidia ^[3] ; Koeberl, Christian ^{[3, 4]} ; Kenkmann, Thomas ^[5]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Inst Geosci, Campinas, SP - Brazil

^[2] Petroleo Brasileiro SA, Petrobras - Brazil

^[3] Univ Vienna, Dept Lithospher Res, A-1090 Vienna - Austria

^[4] Nat Hist Museum, A-1010 Vienna - Austria

^[5] Univ Freiburg, Inst Geowissensch Geol, D-79104 Freiburg - Germany

• Tipo de documento: Artigo Científico
• Fonte: METEORITICS & PLANETARY SCIENCE; v. 47, n. 1, p. 51-71, JAN 2012.
• Citações Web of Science: 16

Resumo

Varge (a) over tildeo Dome (southern Brazil) is a circular feature formed in lava flows of the Lower Cretaceous Serra Geral Formation and in sandstones of the Parana 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 12 km 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 Piramboia formations. We present the morphological/structural characteristics of Varge (a) over tildeo 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 Varge (a) over tildeo Dome, making it one of the largest among the rare impact craters in basaltic targets known on Earth. (AU)

• Processo FAPESP: 04/03295-2 - Caracterizacao geologica e geofisica do domo de vargeao (sc) a partir de imagens de sensores remotos e de dados magnetometricos e sismicos.
• Beneficiário: Cesar Kazzuo Vieira
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 01/01068-0 - Construção de imagens e inversão de atributos de reservatório através do processamento sísmico
• Beneficiário: Martin Tygel
• Modalidade de apoio: Auxílio à Pesquisa - Temático