Vargeão Dome is a

meteorite A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical ...

crater A crater is a landform consisting of a hole or depression (geology), depression on a planetary surface, usually caused either by an object hitting the surface, or by geological activity on the planet. A crater has classically been described ...

Santa Catarina State Santa Catarina () is one of the 27 federative units of Brazil. It is located in the centre of the country's Southern region. It is bordered to the north by the state of Paraná, to the south by the state of Rio Grande do Sul, to the east by t ...

, Brazil, straddling the

municipalities A municipality is usually a single administrative division having municipal corporation, corporate status and powers of self-government or jurisdiction as granted by national and regional laws to which it is subordinate. The term ''municipality' ...

of Vargeão, Faxinal dos Guedes, and

Passos Maia Passos Maia is a municipality in the state of Santa Catarina in the South region of Brazil. The municipality contains part of the Araucárias National Park, a conservation unit created in 2005. See also *List of municipalities in Santa Catari ...

. The crater is an almost perfectly circular depression with steep walls, in diameter and up to deep, relative to its rim. It is of

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

age, or about 123 ± 2 Ma. The meteorite impacted on the

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

ic rocks of the Serra Geral Formation (

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

/Cretaceous). The crater displays several concentric rings and radial faults, and an eroded central bulge. The latter consists of impact breccias and

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s from the

Botucatu Botucatu is a city in the southeastern region of Brazil and is located from São Paulo, the capital of the state of São Paulo. It has an estimated population of 148,130 (as of 2020) in an area of . It lies on the top of a plateau ( high). Botuca ...

/ Pirambóia Formation (Cretaceous/

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

), which have been displaced about above their mean depth in the surrounding area. At least four post-impact lava flows have been identified between the rim and core. The impact origin of the structure is attested by the presence of shatter cones and

shocked quartz Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. Under intense pressure (but limited temperature), the crystalline structure of quartz is deformed along planes inside the crystal. These pla ...

grains.

Discovery and studies

In 1978, Brazilian geologists A. Paiva Filho, C.A.V. Andrade and L.F. Scheibe identified an anomalous circular structure in radar images produced by the RADAMBRASIL survey, and called it the Vargeão Dome. In the early 1980s, E. Barbour Jr. and W.A.G. Correa studied the structure in detail, in the context of oil/gas surveys of the area, and proposed a volcanic/

tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

origin for the structure. In 1982, Á. P. Crósta and A. Paiva Filho identified it as an impact crater. Shocked quartz was identified by M. V. Coutinho in 1987, and the occurrence of

maskelynite Maskelynite is a glassy material found in some meteorites and meteorite impact craters. Typical samples are similar in composition to plagioclase feldspar, and revert to that mineral when melted and recrystallized. It was named after British peopl ...

glass was reported by J. Hachiro and others in 1993

Conservation status

The area around and inside the crater has been heavily farmed since the end of the 19th century; Vargeão's

city hall In local government, a city hall, town hall, civic centre (in the UK or Australia), guildhall, or municipal hall (in the Philippines) is the chief administrative building of a city, town, or other municipality. It usually houses the city o ...

is located inside the crater, near the southern rim. Nevertheless, the crater is still well-preserved. The local population is well aware of the impact origin of the structure, to the point that the town's official nickname is ''Meteor City''.

References

External links

Earth Impact Database
{{DEFAULTSORT:Vargeao Dome Impact craters of Brazil Cretaceous Brazil Cretaceous impact craters Landforms of Santa Catarina (state) Craters