PALYNOLOGICAL EVALUATION OF THE FAMENNIAN PROTOSALVINIA (FOERSTIA) ZONE IN THE AMAZON BASIN, NORTHERN BRAZIL - A PRELIMINARY-STUDY

Miospore assemblages recovered from a shallow borehole (Caima PH-2) an d outcrops near the Tapajos River (Itaituba area), on the southern mar gin of the Amazon Basin, permit the correlation of the Protosalvinia Z one in this region with the equivalent of the uppermost part of the VC o miospore Zone in the eastern USA. Therefore it is dated as late (not latest) Famennian (postera to early expansa conodont Zones). The Prot osalvinia Zone also exists in the eastern USA but cannot be considered there as one single floral zone, its age varying, from place to place , from the middle to the late (not the latest) Famennian (one of the m arginifera Zones to one of the expansa conodont Zones). As demonstrate d in well 1RX1AM, miospore evidence points to an important intraformat ional gap separating the lower and upper parts of the Curiri Formation . The lower section (which contains the Protosalvinia Zone) lacks diam ictites, and rests conformably on the upper, non-radioactive shales of the uppermost Barreirinha Formation, of similar late Famennian (VCo) age. The 'upper Curiri unit' contains diamictites, and invariably disp lays a latest Famennian (late 'Strunian', LE-LN) age; it may constitut e the whole formation in areas where 'lower Curiri' strata are missing , due to either erosion or non-deposition.