PALYNOLOGY OF THE EARLY TO MIDDLE DEVONIAN PESCADO FORMATION, SUBANDEAN RANGE, SALTA PROVINCE, ARGENTINA

Abstract

We present the palynoflora recovered from the Pescado Formation in the Subandean Range, Salta Province, Argentina. The palynological assemblage comprises well-preserved marine and terrestrial palynomorphs, including cryptospores (one species), trilete spores (16 species), acritarchs (six species), prasinophytes (three species), and chlorophytes (three species). Based on the quantitative analysis and stratigraphic distribution of palynomorphs, two palynological associations are recognized (RC1, RC2). The presence of Dictyotriletes emsiensis morphon and Acinosporites apiculatus, together with Duvernaysphaera angelae and D. tenuicingulata, suggests a late Emsian–Eifelian age for RC1 and RC2. The studied assemblages contain many taxa in common with other coeval assemblages of Gondwana that confirm the paleogeographical relationships among the Argentine Precordillera, the Tarija Basin, and the southern Chacoparaná Basin in Uruguay. The relative abundance of the palynomorphs encountered suggests a marine depositional environment close to the paleo-shoreline for the RC1, and a more distal marine setting for the RC2, possibly nearshore, reflecting the Eifelian transgression. This event, already documented by different authors, is also recognized in the southern portion of the Tarija Basin.