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Type: Artigo
Title: Insights about the formation of a complex impact structure formed in basalt from numerical modeling : the Vista Alegre structure, southern Brazil
Author: Rodrigues Vasconcelos, Marcos Alberto
Rocha, Fernanda Farias
Crosta, Alvaro Penteado
Wuennemann, Kai
Gueldemeister, Nicole
Leite, Emilson Pereira
Ferreira, Julio Cesar
Reimold, Wolf Uwe
Abstract: We present the outcomes of simulations of the formation of the Vista Alegre impact structure, Parana Basin, Brazil. The target comprised a thick sequence of volcanic rocks of predominantly basaltic composition of the Serra Geral Formation that had been deposited on top of sedimentary rocks (sandstones) of the Piramboia/Botucatu formations. The cratering process was modeled using the iSALE shock physics code. Our best-fit model suggests that (1) the crater was originally ~10 km in size; (2) it was formed in ~115 s by a stony projectile of 1000 m in diameter, for an assumed impact velocity of 12 km s(-1); (3) target rocks underwent a peak pressure of ~20 GPa, in agreement with previous petrographic investigations of shock deformation. Furthermore, the model points out that the sedimentary strata below the layer of volcanic rocks were raised by ~650 meters at the central part of the crater, which resulted in the current partial exposure of the sandstones at the surface. The outcomes of our modeling suggest that parameters like cohesion and strength of the target rocks, after shock compression, determined the final morphology of the crater, especially the absence of a topographically prominent central peak. Finally, the results of the numerical modeling are roughly in agreement with gravity data over the structure, in particular with respect to the presence of the uplifted sedimentary strata, which are responsible for a low gravity signature at the center of the structure
Subject: Basalto
Country: Estados Unidos
Editor: Wiley
Rights: Fechado
Identifier DOI: 10.1111/maps.13298
Date Issue: 2019
Appears in Collections:IG - Artigos e Outros Documentos

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