翻訳と辞書 ・ Colón Province
・ Colón River F.C.
・ Colón Sudeste
・ Colón, Buenos Aires
・ Colón, Cuba
・ Colón, Entre Ríos
・ Colón, La Libertad
・ Colón, Nariño
・ Colón, Panama
・ Colón, Putumayo
・ Colón, Querétaro
・ Colón, Venezuela
・ Colóquios dos simples e drogas da India
・ Colômbia
・ Colônia 31 de Março Biological Reserve
・ Colônia crater
・ Colônia do Gurguéia
・ Colônia do Piauí
・ Colônia Leopoldina
・ Colônia River
・ Colônia Santo Antônio (Amaral Ferrador)
・ Colônia, Rio de Janeiro
・ Colún Beach
・ Colún River
・ Colăcelul River
・ Colțea
・ Colțea Brașov
・ Colțea București
・ Colțești
・ Colți
|
|
| Colônia crater ： ウィキペディア英語版 |
Colônia crater
The Colônia crater is a presumed impact crater located in the municipality of São Paulo, Brazil. It is a round bowl-shaped depression, without any obvious central bulge, with a diameter of about 3.6 km, bounded by a circular ring of hills about 125 m high relative to the inner depression. Its approximate location is 23°52′15″ South and 46°42′30″ West, 770 m above sea level.〔 The name comes from the town district of Colônia located just north of the feature.
==Geology and ecology==
Some geologists believe that the feature was created by the impact of a meteorite with a diameter of about 200 m. It was formed between 1 million〔Cláudio Riccomini, Álvaro Crósta, Marie-Pierre Ledru, Renato Luis Prado, Bruno Turq, Lucy Sant'Anna, José Ferrari, and Wolf Reimold (2011), ''The Colônia structure, São Paulo, Brazil''. Meteoritic & Planetary Science, to appear.〕 to 20 million years ago,〔 in crystalline basement rocks 600 to 700 millions of years old. In any case, it would be one of the youngest South American impact craters known. It is partially filled by turfaceous sediment with maximum depth of 275 m,〔 which provides a precious record of ancient environment. The upper 8 m, in particular, have provided a detailed climate and ecological record of the last 130,000 years; the complete record may stretch back to 2.5 million years ago.〔
Data from seismic and other surveys indicate that below the sediment there are about 50 to 65 m of fragmented rock deposits, and another 50 m of shocked or deformed basement rock. Sediment analysis indicate that until 18,000 years ago a lake occupied the central part of the crater, which has become a swamp.〔Paulo Gomes Varella (2009) (A CRATERA DE COLÔNIA ) (in Portuguese).〕 The crater is drained towards the east by the Vargem Grande creek into the adjacent Billings Reservoir.〔
The tentative identification as an impact crater is based mainly on geomorphology, faulting pattern, and on the exclusion of other possible formation mechanisms. In particular, there are no carbonate rocks that could produce to karstic sinkholes. As of 2011 there were no reports of definite evidence, such as shatter cones or shocked quartz. To find such evidence one would have to drill through the sediment fill.〔〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Colônia crater」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|