Abstract: Sedimentary-Tectonic Evolution of Brazilian Craton--Comparison with North America
Paulo C. Soares, L. L. Sloss
Correlatives of certain of the major stratigraphic sequences recognized in the Phanerozoic record of the North American craton are identified on the Brazilian craton. The earliest of the Brazilian sequences (Alpha sequence, Cambrian-Early Ordovician) is represented only in the Amazon basin where it lies on Precambrian basement and is separated by an unconformity from the overlying Beta sequence, Late Ordovician and Early Silurian in age. The Beta sequence is confined largely to the Amazon basin, although recent data suggest representation in the Paranaiba basin.
Major Phanerozoic sedimentation beyond the Amazon basin began with overstep of an interregional unconformity in the Early Devonian, marking the base of the well-documented Devonian-Early Carboniferous Gamma sequence. The Delta sequence, deposited on a fourth interregional unconformity, extends from the Late Carboniferous to a major unconformity separating Upper Permian and Middle(?) Triassic strata. The latter form the base of the Delta-A sequence, which includes continental and volcanic units of the Parana and Parnaiba basins with an upper age limit of earliest Cretaceous. The succeeding postvolcanic Epsilon sequence, Cretaceous, is topped by an unconformity above which is the Tertiary Zeta sequence.
There are obvious similarities between the Paleozoic histories of the Brazilian and North American cratons; major differences appear in the Mesozoic record and its interpretation. Geodynamic implications in terms of the evolution of Gondwana and the Atlantic require further exploration.
AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC