Resumo

TOVAR, Rosa E.; FASTOVSKY, David E.  e  BENAMMI, M.. Pedogenic calcrete in the Late Creataceous of Michoacán, Mexico. Bol. Soc. Geol. Mex [online]. 2012, vol.64, n.1, pp.61-70. ISSN 1405-3322.

Paleosols and sedimentological studies are useful tools in the reconstruction of past environments; they are also used as stratigraphic markers for correlation in small areas or for determining the rate of deposition. The oldest known paleosols are from the Precambrian, however the most studied are those from the Quaternary. The purpose of this work is to give a brief review of the uses and applications of paleosols, with a special emphasis on pedogenic calcretes, concluding with a case study in the Barranca Los Bonetes, Michoacán. Barranca Los Bonetes, in the south-center of Mexico, bears a volcaniclastic succession of Late Cretaceous age and the oldest hadrosaurs known in Mexico. The volcaniclastic succession contains pedogenic calcretes, identified as such by macro- and microstructural characteristics such as roots, and alpha and beta textures. Based on the environmental requirements for the formation and accumulation of calcareous paleosols, we infer an arid or semi-arid climate in the study area during the periods of non-deposition during the Cretaceous. This study is, to date, one of the few studies in Mexico in which pre-Quaternary paleosols have been used as a tool for reconstructing past environments.

Palavras-chave : Cretaceous paleosols; calcretes; paleoenvironment; Mexico; barranca Los Bonetes; dinosaurs.

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