Vista Alegre - Hypervelocity Impact Crater

Alternate Names N/A
Coordinates 25° 56' 52" S; 52° 41' 32" W
Notes
  1. Paraná state, S. Brazil.
Country Brazil
Region Paraná
Date Confirmed 2010
Notes
  1. Confirmed by presence of shatter cones in fine-grained volcanic rock (Crósta et al., 2004).
Buried? No
Drilled? No
Target Type Mixed
Notes
  1. Mostly basalt, with uplifted sandstone from Jurassic to Cretaceous.
Sub-Type Basalt, Sandstone
Apparent Crater Diameter (km) 9.5 km
Age (Ma) 111 - 134
Notes :
  1. 111-134 Ma based on a minimum 40Ar/39Ar age of impact melt fragments (Crósta et al., 2019). Previous work estimated the impact occurred during Mesozoic time in Cretaceous basalts (Acevedo et al., 2015).

Method :
  1. Stratigraphy
Impactor Type Unknown

Advanced Data Fields

Notes

Local Language
N/A
Erosion
6
  1. Crater-fill removed.
Final Rim Diameter
Unknown
Apparent Rim Diameter
9.5 km
  1. Circular structure has a diameter of 9.5 km (Crosta et al., 2004).
Rim Reliability Index
2
  1. Stratigraphic uplift at least ~700-800 m (Crósta et al., 2010). Central uplift has a vertical displacement of nearly 900 m (Crosta et al., 2013).
Crater Morphology
Complex
Central Uplift Diameter
Unknown
Central Uplift Height
180 m
Uplift Reliability Index
2
Structural Uplift
900 m
Thickness of Seds
Unknown
Target Age
Mesozoic
Marine
No
Impactor Type
Unknown
Other Shock Metamorphism
Feather features
  1. (Crosta and Reimold, 2017)
Shatter Cones
Yes
  1. Shatter cones were first reported in an abstract by (Crosta et al., 2004). Shatter cones in a fine-grained volcanic rock (basaltic to basalt-andesite in composition; high-Fe tholeiite; (Crosta et al., 2010)) occur in the form of large (and small) clasts within polymict breccia. The shatter cone-bearing breccias are found at different locations within the structure, separated by several kilometers. The nested shatter cones range in size from ~0.5 to 20 cm for individual cones, and up to half a meter for complete assemblages (Crosta et al., 2009) (Crosta et al., 2010). In some cases, almost complete and perfect cones were found (Crosta et al., 2010). Shatter cones formed in fine-grained basalt and are decorated with a continuous quenched melt film consisting of a crystalline phase, mica, and amorphous material (Pittarello et al., 2015). Shatter cones developed in almost unshocked basaltic volcanic clasts within polymict breccias, mainly composed of plagioclase, pyroxene, and magnetite, and are covered by a melt film (Pittarello et al., 2010).
Planar Fractures
Yes
  1. (Crosta and Reimold, 2017)
Planar Deformation Features
Yes
  1. PDFs found in isolated quartz grains within breccias (Crosta et al., 2004). Some sandstone clasts from polymict breccia containing quartz grains with abundant PDFs, most of them with one or two sets (Fig. 14; Crosta et al., 2010). The polymict breccias contains clasts of quarzose sandstone with the development of at least two sets of PDFs per grain with orientations allowing for estimations of ~ 20GPa shock pressure (Pittarello et al., 2010).
Diaplectic Glass
Yes
  1. Complete transformation of plagioclase to maskelynite found in the outer regions of the crater (Pittarello et al., 2010).
Coesite
No
  1. Did not find in literature.
Stisovite
No
  1. Did not find in literature.
Crater Fill
LB, MB
  1. Polymict impact breccias occur at central portion of the crater; consist of weathered and highly deformed angular basalt fragments, dolerites, gabbros, sandstones and fragmented minerals, in a medium to fine-grained matrix (Crosta et al, 2004). Shocked sandstone clasts in impact breccia (suevite); suevite filled the crater before hydrothermal circulation was established; shatter cones found within polymict breccia (Pittarello et al, 2015).
Proximal Ejecta
Unknown
Distal Ejecta
Unknown
Dykes
Unknown
Volume of Melt
Unknown
Depth of Melting
Unknown

References

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A P Crósta, C Kazzuo-Vieira, A Schrank (2004) Vista Alegre: A newly discovered impact crater in Southern Brazil, Meteoritics and Planetary Science Supplement 39, p. 5051, url

A P Crósta, C Koeberl, D Jalufka (2009) Shatter cones confirm the Vista Alegre meteorite impact structure in the Parana flood basalt province, southern Brazil, Abstracts with Programs - Geological Society of America 41(7), p. 532, Geological Society of America (GSA), Boulder, CO, url

W D MacDonald, A P Crósta (2009) Impact structures in Serra Geral Basalt, southern Brazil, Meteoritics & Planetary Science 44, SUPPL., p. 0-Abstract 5163, Meteoritical Society, Fayetteville, AR, url

L Pittarello, C Koeberl, A P Crósta (2010) Shock features in rocks from the Vista Alegre impact structure (Brazil), Abstracts with Programs - Geological Society of America 42(5), p. 172, Geological Society of America (GSA), Boulder, CO

Alvaro P Crósta, C Koeberl, R A Furuie, C Kazzuo-Vieira (2010) The first description and confirmation of the Vista Alegre impact structure in the Parana flood basalts of southern Brazil, Meteoritics & Planetary Science 45(2), p. 181-194, Meteoritical Society, Fayetteville, AR, url, doi:http://dx.doi.org/10.1111/j.1945-5100.2010.01015.x

V M Pinto, L A Hartmann (2011) Flow-by-flow chemical stratigraphy and evolution of thirteen Serra Geral Group basalt flows from Vista Alegre, southernmost Brazil, Anais da Academia Brasileira de Ciencias 83(2), p. 425-440, Academia Brasileira de Ciencias, Rio de Janeiro, url, doi:http://dx.doi.org/10.1590/S0001-37652011000200006

L Pittarello, C Koeberl, A P Crósta (2011) Melt on the striated surface of shatter cones in basalt, Meteoritics & Planetary Science 46, SUPPL., p. 1, Meteoritical Society, Fayetteville, AR, pdf, doi:http://dx.doi.org/10.1111/j.1945-5100.2011.01241.x

V M Pinto, L A Hartmann, W Wildner (2011) Epigenetic hydrothermal origin of native copper and supergene enrichment in the Vista Alegre District, Parana basaltic province, southernmost Brazil, International Geology Review 53(9-10), p. 1163-1179, Taylor & Francis, Abingdon, url, doi:http://dx.doi.org/10.1080/00206810903464547

A P Crósta, F Jourdan, C Koeberl (2012) 40Ar/ 39Ar dating of the Vista Alegre impact crater, Brazil, International Geological Congress, Abstracts = Congres Geologique International, Resumes 34, p. 3781, [International Geological Congress], [location varies]

C Guerin, M Faure (2013) Un nouveau Toxodontidae (Mammalia, Notoungulata) du Pleistocene superieur du Nordeste du Bresil, Geodiversitas 35(1), p. 155-205, Editions Scientifiques du Museum, Paris, doi:http://dx.doi.org/10.5252/g2013n1a7

L Pittarello, F Nestola, C Viti, A P Crósta, C Koeberl (2015) Melting and cataclastic features in shatter cones in basalt from the Vista Alegre impact structure, Brazil, Meteoritics & Planetary Science 50(7), url, doi:10.1111/maps.12466

N Posnov, G R Osinski, R L Flemming, A Pontefract, Alvaro P Crósta (2019) Hydrothermal alteration of Vista Alegre basalts: Implication for the search for life on Mars, 50th Lunar and Planetary Science Conference 2019 (LPI Contrib. No. 2132)

Jitse Alsemgeest, Fraukje M. Brouwer, Luis F. Auqué, Natalia Hauser, Wolf Uwe Reimold (2021) Hydrothermal alteration at the basalt-hosted Vista Alegre impact structure, Brazil, Meteoritics and Planetary Science 56(12), p. 2155-2174, University of Arkansa, doi:10.1111/maps.13763