| 词条 | Cerro do Jarau crater |
| 释义 |
| name = Cerro do Jarau crater | other_name = | photo = | photo_size = | photo_alt = | photo_caption = | map = Brazil | map_alt = | map_caption = Location of the crater in Brazil | map_size = | location = Paraná Basin | label = | label_position = | coordinates = {{coord|30|11|53.3|S|56|32|40.8|W|display=inline,title}} | coordinates_ref = [1] | confidence = Probable[1] | diameter = ~{{convert|13.5|km|mi|abbr=on}} | depth = | rise = >{{convert|200|m|ft|abbr=on}} | imp_size = | age = 105 to 128.7 Ma Early Cretaceous | exposed = Yes | drilled = No | bolide = | translation = | language = | pronunciation = | topo = | access = | country = {{BRA}} | state = Rio Grande do Sul | province = Sudoeste | district = Campanha Ocidental | municipality = Quaraí }}Cerro do Jarau crater is a {{convert|13.5|km|mi}} diameter circular feature in the Paraná Basin, Rio Grande do Sul in southern Brazil, close to the border with Uruguay. The Russian Academy of Sciences lists the structure as a probable impact crater.[1] DescriptionCerro do Jarau is a prominent, approximately {{convert|13.5|km|mi}} wide, circular landform rising more than {{convert|200|m|ft}} above the plains of the "pampas" in southern Brazil. The name (meaning Jarau hills) comes from the prominent crests of silicified sandstones, which form a semiring of elevated hills in the northern part of the structure. The origin of this structure has been debated for decades, and varied suggestions of its formation include either endogenous tectonic processes or large meteorite impact. However, no conclusive evidence to support either hypothesis has been presented to date. This structure was formed in Mesozoic volcano-sedimentary rocks of the Paraná Basin and consists of the Jurassic to Cretaceous Guará (sandstones), Botucatu (sandstones), and Serra Geral (basalts) formations. The Botucatu Formation sandstones are intensely silicified and deformed, and were subject to radial and annular faulting. Investigations at Cerro do Jarau identified the occurrence of parautochthonous monomict lithic breccia and polymict breccias resembling suevite and striated joint surfaces resembling crude shatter cones in sandstones and basalts. In addition, the first mineral deformation studies show the presence of rare planar features in quartz clasts in polymict breccias. The identification of these features at Cerro do Jarau is suggestive of an impact origin for the structure. If confirmed by further investigation of possible shock features, Cerro do Jarau would become the sixth known impact structure in Brazil, as well as the fifth basalt-hosted impact structure on Earth.[2] The crater formed in the same basaltic unit as the nearby Vista Alegre crater and the Vargeão Dome.[3] The age of impact has been given at 117 Ma (Aptian),[4] or a broader range from 128.7 to 105 Ma.[1] See also
References1. ^1 2 3 Mikheeva, 2017 2. ^Crósta et al., 2010 3. ^Crósta & Vasconcelos, 2013, p.1 4. ^Exoss, 2017 Bibliography
6 : Impact craters of Brazil|Possible impact craters on Earth|Cretaceous impact craters|Cretaceous Brazil|Landforms of Rio Grande do Sul|Paraná Basin |
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