American Museum of Natural HistoryBuilding a banded iron formation [ENG]Zoom + / -Formacoes ferriferas bandadas (tambem conhecidas como itabirito, jaspilito, taconito, ironstone bandado ou BIFs) sao rochas sedimentares quimicas de idade pre-cambriana compostas por bandas alternadas de oxido de ferro (hematita, Fe2O3, ou magnetita, Fe3O4) e bandas chert e/ou jasper. O bandamento tipico e caracterizado pela repeticao de bandas ricas em oxido de ferro com cor cinza a preta, alternando com bandas pobres em oxido de ferro, geralmente de cor vermelha ou branca, e de espessuras milimetricas ou centimetricas.As formacoes ferriferas bandadas tiveram sua formacao quase toda restrita ao periodo Pre-Cambriano (>542 Ma), sendo os maiores depositos formados durante o Arqueano e o Paleoproterozoico (formacoes ferriferas do tipo Algoma e Lago Superior) e os menores depositos durante o Neoproterozoico (formacoes ferrifera do tipo Rapitan e Urucum).Algumas das formacoes rochosas mais antigas, se formaram ao longo de mais de 3.700 milhoes de anos atras, e incluem camadas de ferro bandado.Camadas bandadas ricas em ferro, em sua grande maioria, foram depositadas entre 2.400 e de 1.900 milhoes de anos atras. Ironstones fanerozoicos geralmente tem genese diferente.As formacoes ferrifera bandadas sao uma importante fonte exploratoria de minerio de ferro, como nas regiao de Pilbara do Oeste da Australia e o Grupo Animikie em Minnesota. Os maiores depositos de minerio de ferro se encontram no Brasil e na Australia, e correspondem ao depositos de Carajas e Hamersley, respectivamente.FONTEBanded iron formations (also known as banded ironstone formations or BIFs) are distinctive units of sedimentary rock that are almost always of Precambrian age.A typical BIF consists of repeated, thin layers (a few millimeters to a few centimeters in thickness) of silver to black iron oxides, either magnetite (Fe3O4) or hematite (Fe2O3), alternating with bands of iron-poor shales and cherts, often red in color, of similar thickness, and containing microbands (sub-millimeter) of iron oxides.Some of the oldest known rock formations, formed over 3,700 million years ago, include banded iron layers. Banded layers rich in iron were mostly deposited between 2,400 and 1,900 mya. Phanerozoic ironstones generally have a different genesis.Banded iron beds are an important commercial source of iron ore, such as the Pilbara region of Western Australia and the Animikie Group in Minnesota.External linkBanded Iron Formations (BIFs)YouTubeThis video shows the creative process of the formation of Banded Iron Formations. It is intended as an educational video for High School Students made by two Australian Year 12 students (In about an hour). We hope you enjoy and don't subscribe because I will not be posting any more videos. Unless for some reason I go viral. Doubt it.Episode 2 - Banded Iron FormationsYouTubeEpisode 2 of the Early Earth series, this video features Dr. Russell Shapiro (California State University, Chico) and Dr. John Spear (Colorado School of Mines) in the Wind River Range, WY, where they discuss Banded Iron Formation dated to ~2.4 Billion years ago. O maior Mamute do mundo e achado em Dudinka na peninsula de Taimyr na Russiahttps://oglobo.globo.com/sociedade/ciencia/encontrado-maior-mamute-dos-ultimos-100-anos-6300421Wool Mammoth Find in Russia Flesh Bones & Furhttp://www.ibtimes.co.in/child-discovers-intact-remains-of-woolly-mammoth-391531https://en.wikipedia.org/wiki/Sopkarga_mammothhttp://www.dailymail.co.uk/sciencetech/article-2212946/Almost-intact-carcass-30-000-year-old-woolly-mammoth-11-year-old-boy.html Comprado em Ouro Preto - MG - Brasil Calcita obtida no Rio