NEW PALYNOLOGICAL RECORDS FROM THE GLACIOMARINE DEPOSITS OF THE EL PASO FORMATION (LATE SERPUKHOVIAN-BASHKIRIAN) IN THE ARGENTINE PRECORDILLERA: BIOSTRATIGRAPHICAL IMPLICATIONS

摘要

New palynological information from the El Paso Formation cropping out at the southern Sierra de Barreal (Calingasta-Uspallata Basin), San Juan Province, Argentina is presented. The palynologic assemblages were recovered from the middle to upper part of the section. Abundant trilete (75-90%) and hilate (1-5%) spore species are recognized: Cyclogranisporites rinconadensis, Apiculatisporis variornatus, Raistrickia rotunda, Tricidarisporites gutii, Ahrensisporites sp. cf. A. cristatus, Cristatisporites stellatus, Indotriradites volkheimeri, Vallatisporites ciliaris and Psomospora detecta, among others. Also, subordinate pollen grains (1.5-20%): Circumplicatipollis plicatus, Costatascyclus crenatus, Plicatipollenites sp. cf. P. malabarensis, Potonieisporites spp. and Divarisaccus sp. cf. D. stringoplicatus. Recycled and autochthonous acritarchs (e.g., Cymatiogalea sp., Gorgonisphaeridium sp., Verhyachium sp.) and Zygnematalean algae (Tetraporina sp., Brazilea scisa) with less of 2.5% are also present. We propose a late Serpukhovian-Bashkirian age, and a correlation with the Subzone A of the Raistrickia densa-Convolutispora muriornata (DM) Biozone to the El Paso assemblages.