Estudo paleoambiental preliminar do cretaceo da bacia potiguar

lntegration of micropaleontological information, based mainly on the study of foraminifers and palynomorphs from seven wells, led to the recognition of the paleoenvironmental development of the Potiguar Basin from the Alagoas to the Maastriehtian. Seventeen bioestratigraphical zones and one subzone have been recognized. Seven episodes - four transgressive and three regressive - could be detected between the Early-Middle Albian to the Maastriehtian, and have been regarded as result from relative global fluctuat ions of the Cretaeeous sea level. A distinctive hiatus of Late Albian age may be inferred from the absenee of diagnostic index fossils. Fine grained clastic sediments deposited during the Late Cenomanian and the Early Turonian show evidence of anoxia. This is assumed to be synchronous with similar events detected elsewhere in many Cretaceous basins (including some in Brasil). Carbonatic cycles have been found to occur in the Early-Middle Albian, Early-Middle Cenomanian, Turonian and Coniacian/Santonian, each of them being represented by shallow neritic paleoecological units with distinctive microfaunal assemblages: Early-Middle Albian - Favusella spp., calcispherulids association; Early-Middle Cenomanian - Trocholina spp. association; Turonian - marine ostracods-gastropods-worm tubes association; Santonian - Buliminidae-Siphogenerinoides spp.-Dinogymnium spp.-Deflandrea spp. association.