Abstract

CARRASCO-VELAZQUEZ, Baldomero Everardo; MARTINEZ-HERNANDEZ, Enrique; RAMIREZ-ARRIAGA, Elia  and  SOLE VINAS, Jesús. Stratigraphy of the Pliocene Metztilán Formation (state of Hidalgo, central-eastern Mexico). Bol. Soc. Geol. Mex [online]. 2008, vol.60, n.1, pp.83-99. ISSN 1405-3322.

The study of continental rocks in the Metztitlán area allows to define a new lithostratigraphic unit. The Metztitlán Formation is formed by conglomeratic rocks which in the base have elastics of igneous extrusive rocks (basalt) and toward the top of the conglomeratic column change to elastics of carbonate rocks derived from cretaceous sedimentary rocks. The column of continental rocks rest over marine Albian-Cenomanian rocks with an unconformity contact. It is proposed to formalice the lithostratigraphy of continental rocks in the area as a type locality of the Metztitlán Formation is proposed the Santuario de las Cactáceas en Metztitlán. Toward the northeast of Metztitlán in Zacualtipán-Atotonilco El Grande areas there is a column of Pliocene volcanic rocks which are part of the eastern part of the Transmexican Volcanic Belt. The outcrops close to the deposit area of the Metztitlán Formation are of calcareous rocks of the Upper Tamaulipas Formation. The lithologic composition of the clasts in the Metztitlán Formation show that at beginning there were rivers that primary transport clasts of the Pliocene volcanic rocks coming from the Zacualtipán area. After formed alluvial fans that transported clasts of the surrounding cretaceous rocks. Palinologic studies of matrix in the conglomeratic rocks give Pliocene age in the Metztitlán Formation, similar to the radiometric age of the clasts of basalt (Pliocene). Suggesting that the calcareous clasts in the Metztitlán Formation were deposited after the magmatic event of the Transmexican Volcanic Belt.

Keywords : Pliocene; alluvial fans; Metztitlán; stratigraphy.

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