6 research outputs found

    Terrestrial impact structures as geoheritage: an assessment method of their scientific value and its application to Brazil

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    Terrestrial impact structures are geological and geomorphological features with particular importance to understand the history and evolution of the planet. Impact structures are scattered around the world but in many countries these features are under threat, essentially due to anthropic factors. Impact structures with higher scienti c value should be considered as geological heritage and, consequently, be subjected to geoconservation strategies. In order to select the most important impact structures to be properly conserved and managed, this paper proposes a quantitative assessment method of the scienti c value of these structures. The eight Brazilian impact structures were used to test this method that has the potential to be applied to any geological context in any country. The structures known as Araguainha Dome-MT and Serra da Cangalha-TO reached a higher scienti c value, which justi es the need to develop geoconservation strategies and a proper management.The Conselho Nacional de Pesquisa e Desenvolvimento (CNPq / National Council for Research and Development) and the Programa Ciências sem Fronteiras / Science Without Borders Programme are acknowledged for the support of the postdoctoral grant No 233209/2013-1 of the 1st author. The work was co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização), project ICT (UID/ GEO/04683/2013) with reference POCI-01-0145- FEDER-007690 and Portuguese funds provided by Fundação para a Ciência e Tecnologia.info:eu-repo/semantics/publishedVersio

    Vista Alegre: A Newly Discovered Impact Crater In Southern Brazil

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    [No abstract available]39SUPPL.Kazzuo-Vieira, (2004) Meteoritics and Planetary Science, , This issueCrósta, A.P., (1987) Research in Terrestrial Impact Structures, pp. 30-38. , Braunschweig: F. ViewegRomano, Crósta, (2004) 35th Lunar and Planetary Science Conferenc

    The first description and confirmation of the Vista Alegre impact structure in the Parana flood basalts of southern Brazil

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    Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The Vista Alegre structure, centered at 25 degrees 57'S and 52 degrees 41'W, has been recently proposed as a meteorite impact structure. The 9.5 km-diameter structure is located in the Parana state of southern Brazil, within the Parana Basin, which contains one of the largest and most extensive flood basalt provinces on Earth. The Parana flood basalts belong to the Serra Geral Formation and are temporally related to the opening of the South Atlantic Ocean, having been dated at about 133-132 Ma. Tholeiitic basalts dominate the western portion of Parana state, with some minor rhyodacites. Morphologically, Vista Alegre has a prominent circular outline, in the form of an incomplete ring of escarpments, and an inner depression. The presence of a central uplift is not obvious, but it is inferred by the occurrence of deformed sandstone blocks near the center of the structure. These sandstones are possibly related to the Triassic Piramboia Formation and/or to the Cretaceous Botucatu Formation. These units are normally at stratigraphic depths of about 700-800 m below the present surface in this portion of the Parana Basin. The structure appears to be in an advanced erosion stage and its interior is occupied by a soil cover several meters thick, extensively used for agriculture. As a result there are limited outcrops in the interior of the structure, all of polymict breccias, some of them melt-bearing. We report the extensive occurrence of shatter cones, in the form of fine-grained rock clasts within the polymict breccias. The shatter cone-bearing breccias occur at different locations within the structure, separated by several kilometers. The nested shatter cones range in size from about 0.5 to 20 cm for individual cones, and up to half a meter for complete assemblages. The shatter cones formed in fine-grained Parana flood basalt and might be the first examples of shatter cones in such a rock type. In addition, planar deformation features (PDFs) were found in quartz grains within sedimentary rock clasts of the polymict breccia. These findings confirm the impact origin of the Vista Alegre structure.452181194Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)University of ViennaConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [306829/2006-1

    Geophysical Characterization Of The Structure's Impact Dome Vargeão, Brazil [caracterização Geofísica Da Estrutura De Impacto Do Domo De Vargeão, Brasil]

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    Vargeão Dome constitutes a rare example of a complex meteoritic impact structure formed in the Cretaceous volcanic lava flows of Serra Geral Formation, in South America. This conspicuous circular depression has its center at 26°49′S and 52°10′W and a diameter of 12.4 km. Impact deformation features found at Vargeão include shatter cones in sandstone and basalt, as well as planar deformational features in quartz. Available geophysical data for this structure comprise airborne magnetics and seismic surveys, which were processed and interpreted in combination with remote sensing data, such as digital elevation model generated by the SRTM (Shuttle Radar Topographic Mission) and Radarsat-1 and TERRA/ASTER satellites images. Magnetic and seismic data analysis allowed: (i) to interpret it as shallow structure, with a strongly deformed zone underneath; (ii) to associate a magnetic high spatially coincident with the central portion of the structure to the occurrence of pseudotachylite impact breccia; (iii) to associate the circular magnetic low located near the rim of the structure to the occurrence of large blocks of the Ácidas Chapecó volcanics unit. Favorable exposure of the shocked rocks, combined with easy access, makes this impact structure potentially important for conducting analogue studies of planetary surfaces, thus helping to understand the evolution of solid bodies such as the Moon, Mars, Venus, among others. © 2009 Sociedade Brasileira de Geofísica.273375388Adepelumi, A.A., Fontes, S.L., Schnegg, P.A., Flexor, J.M., An integrated magnetotelluric and aeromagnetic investigation of the Serra da Cangalha impact crater, Brazil (2005) Physics of The Earth and Planetary Interiors, 150, pp. 159-181Adepelumi, A.A., Flexor, J.M., Fontes, S.L., An appraisal of the Serra da Cangalha impact structure using the Euler deconvolution method (2005) Meteoritics and Planetary Science, 40 (8), pp. 1149-1157Alvarez, L.W., Alvarez, W., Asaro, F., Michel, H.V., Extraterrestrial cause for the Cretaceous-Tertiary extinction (1980) Science, 208, pp. 1095-1108Barbour, E.J.R., Corrêa, W.A.G., (1981) Geologia Da Estrutura De Vargeão, SC, p. 65. , Relatório Técnico, PAULIPETROBellieni, G., Marques, L.S., Melfi, A.J., Nardy, A.J.R., Piccirillo, E.M., Roisenberg, A., High- and low-TiO2 flood basalts from Paraná Plateau (Brazil): Petrology and geochemical aspects bearing on their mantle origin (1984) Neues Jahr. Miner. Abh, 150, pp. 273-306Crósta, A.P., (1992) Processamento Digital De Imagens De Sensoriamento Remoto, p. 154. , Editora da Unicamp, CampinasCrósta, A.P., Gaspar, J.C., Candia, M.A.F., Feições de metamorfismo de impacto no Domo de Araguainha (1981) Revista Brasileira De Geociências, 11, pp. 139-146Crósta, A.P., LourençO, F.S., Priebe, G.H., CerrodoJarau, Rio Grande do Sul: A possible new impact structure in Southern Brazil (2010) Large Meteorite Impacts and Planetary Evolution IV, , In: GIBSON RL & REIMOLD WU (Eds.), The Geological Society of America, Special Paper #465 (no prelo)Donofrio, R.R., North American impact structures hold giant field potential (1998) Oil and Gas Journal, 96 (19), pp. 69-83von Engelhardt, W., Matthäi, S.K., Walzebuck, J., Araguainha impact crater, Brazil. The interior part of the uplift (1992) Meteoritics, 27, pp. 442-457Freitas, M.A., Caye, B.R., Machado, J.L.F., (2002) Projeto Oeste De Santa Catarina (PROESC): Diagnóstico Dos Recursos H ́i{dotless}dricos Subterrâneos Do Oeste Do Estado De Santa Catarina, p. 100. , Relatório Técnico: Convênio CPRM/ Governo do Estado de Santa CatarinaFrench, B.M., (1998) Traces of Catastrophe: A Handbook of Shock-metamorphic Effects In Terrestrial Meteorite Impact Structures, p. 130. , Lunar and Planetary Institute, HoustonGrieve, R.A.F., Masaitis, V.L., The economic potential of terrestrial impact craters (1994) International Geology Review, 36 (2), pp. 105-151Harris, J.R., Viljoen, D.W., Rencz, A.N., Integration and visualization of geoscience data (1999) Remote Sensing For the Earth Sciences - Manual of Remote Sensing, 3, pp. 307-354. , In: RENCZ AN (Ed.), John Wiley and Sons IncJacobsen, B.H., A Case for upward continuation as a standard filter for potential-field maps (1987) Geophysics, 52 (8), pp. 1138-1148Koeberl, C., Craters on the moon from Galileo to Wegener: A short history of the impact hypothesis, and implications for the study of terrestrial impact craters (2001) Earth, Moon and Planets, 85-86, pp. 209-224Lana, C., Souza Filho, C.R., Marangoni, Y.R., Yokoyama, E., Trindade, R.I.F., Tohver, E., Reimold, W.U., Structural evolution of the 40 km wide Araguainha impact structure, central Brazil (2008) Meteoritics and Planetary Science, 43 (4), pp. 701-716Mantovani, M.S.M., Marques, L.S., Souza, M.A., Civetta, L., Atalla, L., Inoccenti, F., Trace element and strontium isotope constraints on the origin and evolution of the Paraná continental flood basalts of Santa Catarina State (Southern Brazil) (1985) J. Petrol, 26, pp. 187-209McHone, J.F., (1986) Terrestrial Impact Structures: Their Detection and Verification With Two New Examples From Brazil, p. 210. , PhD thesis, Universidade de Illinois, Urbana-ChampaignMinty, B.R.S., Simple micro-levelling for aeromagnetic data (1991) Expl. Geoph, 22, pp. 591-592Paiva Filho, A., (2000) Estratigrafia E Tectônica Do Nível De Riodacitos Pórfiros Da Formação Serra Geral, p. 185. , Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista (UNESP), Rio Claro, São Paulo, Tese de DoutoradoPaiva Filho, A., Andrade, C.A.V., Scheibe, L.F., Uma janela estratigráficanooestedeSantaCatarina: ODomodeVargeão (1978) Cong. Bras. De Geol, pp. 408-412. , 30., 1978, Recife, Anais... Recife: SBGStöffler, D., Langenhorst, F., Shock metamorphism of quartz in nature and experiment: I. Basic observation and theory (1994) Meteoritics, 29, pp. 155-181Yilmaz, O., Seismic data processing (1994) Investigations In Geophysics, 2, p. 546. , In: NEITZEL EB & DOHERTY SM (Ed.), Society of Exploration GeophysicistsZalán, P.V., Wolff, S., Conceição, J.C.J., Marques, A., Baciado Paraná (1991) Origem E Evolução De Bacias Sedimentares, p. 415. , In: GABAGLIA GPR & MILANI EJ (Ed.), Ed. Gáve

    Geology and impact features of Vargeao Dome, southern Brazil

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    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)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.4715171Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundo de Apoio ao Ensino, Pesquisa e Extensao (FAEPEX) of the University of Campinas (UNICAMP) [475/2003]Austrian Science Foundation FWF [P21821-N10]University of ViennaFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [01/01068-0, 04/03295-2]CNPq [305203/2003-7, 303065/2004-4]Fundo de Apoio ao Ensino, Pesquisa e Extensao (FAEPEX) of the University of Campinas (UNICAMP) [475/2003]Austrian Science Foundation FWF [P21821-N10
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