Cedrela campbeli, Pliocene Fonseca Basin

The Fonseca basin, located in the Quadrilátero Ferrífero region, in the state of Minas Gerais, southeastern Brazil, is a classic example of tertiary sediments, having aroused the interest of several researchers since the second half of the last century, as it contains deposits of “canga”, lignite and fossiliferous sediments. The main lithotypes constitute the sandy and clayey sediments, probably Eocene, of the Fonseca Formation. These deposits are covered by the ferruginous conglomerates (“canga”) of the Chapada de Canga Formation. The fossiliferous record of the Fonseca Formation is characterized by a wide variety of Angiosperm families, with Melastomataceae and Mimosaceae being the most abundant. The small Fonseca basin, located in the Quadrilátero Ferrífero region, in the state of Minas Gerais, represents a classic example of tertiary sediments in Brazil and is here recognized as an important Brazilian geological and paleontological site. Since the first studies carried out by Gorceix (1876, 1884), the importance of this basin for the knowledge of the Brazilian tertiary flora has been admitted by several researchers. The geological and paleontological interest in the Fonseca basin has both economic and scientific reasons, in both cases due to canga deposits and, mainly, lignite. These, economically exploited occasionally, preserve an exceptional wealth of plant fossils, which attests to the presence of luxuriant vegetation for the age of formation of the deposits.