Geology of the Amazon and Parnaiba Basins

A new Mesozoic coelacanth from Brazil (Sarcopterygii, Actinistia)

“…If the age of the Pastos Bons Formation is Late Triassic (Bigarella, 1973) and Parnaibaia maranhaoensis is the sister taxon of Chinlea sorenseni Schaeffer, 1967, thus this new species possibly belongs to the genus Chinlea. Chinlea was widely distributed upon the joint continent, which was formed by North America and South America in the Late Triassic.…”

“…The Pastos Bons Formation is a deposit of exclusively continental origin (Góes and Feijó, 1994) in the Parnaiba Basin. Bigarella (1973) considered the formation to be Late Triassic in age on the basis of the fossil fish fauna, which includes Lepidotus piauhyensis and Semionotus sp. in a black-shale facies.…”

Electrical Imaging of the Intracratonic Parnaíba Basin, North-Northeast Brazil

“…The carbon-rich carbonates of the Cambro-Ordovician strata constitute the potential candidates for the mapped high conductivity zones. Based on the borehole lithology, Bigarella (1973) has also reported the occurrence of black shales in the Pedra De Fogo formations of Permian age. These black shales would also be a significant contributor to the high conductance.…”

“…As yet, most of the information on the sedimentary sequence has come from the geological mapping of the outcrops and from a few exploratory boreholes drilled by PETROBRAS (Petroleo Brasileiro S.A.) to evaluate the hydrocarbon prospects. The geology and sedimentation history of the Parnaiba basin have extensively been discussed by Mesner and Wooldridge (1964) and Bigarella (1973) and have recently been updated by G6es et at. (1990) in the light of updated information.…”

“…All these three adjoining basins, formed following the opening of the Atlantic ocean, carry thick successions of Mesozoic and Cenozoic sediments. Paleozoic sediments are also believed to be preserved in the graben under a Cretaceous cover, at least in the Marajo and Sao Luiz basins (Meaner and Wooldridge, 1964;Bigarella, 1973). Further to the northeast, concentration of the induced currents in the Atlantic ocean are expected to influence the geomagnetic variations recorded by the array stations.…”