The Brazilian backwoods was once sea

Carboniferous Itaituba-Piauí Sea (IPS) record in rocks from the José de Freitas region, Northern Piauí State

Abstract

A major transgressive-regressive event during the Carboniferous, was responsible for the deposition of Pennsylvanian carbonates from the west of the ancient continent of Gondwana. In the north of currently South America, the Amazonas sedimentary basins record evidence of this intracontinental sea, called Itaituba-Piauí Sea, which to the west was connected with the extinct Panthalassa ocean. These events are identified in the rocks of the northeastern portion of the Parnaíba intracratonic Basin, represented by fossiliferous carbonates from the Upper Member of the Piauí Formation. These rocks, widely known as “Calcário Mocambo”, are found near José de Freitas-PI, presenting a unique record of the Itaituba-Piauí Sea in the Parnaíba basin. Based on the stratigraphic technique of facies analysis, was identified the association of facies or an ancient sedimentary environment know shallow sea deposit, which consists of a succession of fossiliferous peloid carbonate rocks, laterally continuous for hundreds of meters, and interspersed with bituminous shale. Conodonts fossil genus of Neognathodus e Diplognathodus help to determine the Bashkirian age, over 300 millions of years ago, for these marine deposits. The extensive circulation of the sea over Gondwana favored the deposition of correlated marine sequences in several pre-Andean basins and the north and northeast of Brazil.