Nova ocorrência de Crinoidea no Pensilvaniano da Formação Itaituba, Pedreira Caltarém, norte da Bacia do Amazonas

Abstract

Crinoidea from the Pennsylvanian deposits of the Itaituba Formation, Northern Amazonas Basin. The Itaituba Formation comprises part of the marine section of the Tapajós Group in the Amazonas Basin. This unit mainly comprises Pennsylvanian carbonate deposits associated with various marine invertebrate fossils. In this work, we present new records of crinoids in the Itaituba Formation in the Caltarém quarry, north platform of the Amazonas Basin. There are described and taxonomically identified, two genera of crinoids, through the study of columnals and pluricolumnals, in addition to the interpretation of the depositional environment through the analysis of carbonate microfacies. The identified specimens correspond to the species Cyclocaudex aff. typicus Moore & Jeffords, and to the genus Pentaridica Moore & Jeffords (first record in the Itaituba Formation). The textural, compositional, and paleontological analysis suggests four standard microfacies MPF 09, 10, 16, 23) and two faciological zones (ZF 7 E 8). The bioturbated bioclastic wackestones (MFP 09) and bioclastic wackestones/packstones (MFP 10) microfacies, with fossils of brachiopods, crinoids, echinoids, miliolid and fusulinid foraminifera, trilobites, and bryozoans, characterize an interior shelf environment, with a connection to an open marine circulation (ZF 7). The peloidal wackestones (MFP 16) and mudstones (MFP 23) microfacies, with a fossiliferous assemblage limited to brachiopods, echinoids and miliolid foraminifera, characterize a restricted lagoon environment (ZF 8). Paleontological data and microfacies analysis indicate the development of a lagoon environment with a diverse paleofauna of marine invertebrates in the carbonate platform of the northern bord of the Amazonas Basin, in the Monte Alegre County, during the Pennsylvanian. Keywords: taxonomy, echinoderms, microfacies, paleoenvironment, Pennsylvanian.