Cretaceous angiosperm pollen from the Kachaike Formation, south-western Santa Cruz Province, Argentina

<p>Thirty-three angiosperm pollen species are here reported from mid-Cretaceous deposits of the Kachaike Formation, Austral Basin, southern Argentina. <i>Clavatipollenites</i> is the most abundant angiosperm genus, with six well-defined morphological groups recognised on the basis of their reticulum morphology and sculpture. Pollen of eudicots are scarce, represented by tricolpate (<i>Psilatricolpites</i> spp. and <i>Tricolpites</i> spp.), tricolporoidate and tricolporate morphotypes (<i>Dryadopollis</i> spp.). Increasing complexity in the aperture structure is seen throughout the sequence; tricolpate and tricolporoidate forms are recorded in almost all samples, while tricolporate pollen grains are restricted to the middle and upper levels of the unit. The high species richness and abundance of monocolpate-ulcerate angiosperm related to monocots or magnoliids <i>sensu lato</i> recorded in the unit is comparable to that previously recognised in other assemblages from the early and middle Albian of the southern (e.g. Australia) and northern hemispheres (e.g. Western Portuguese basin, Europe). The recorded increase in the number of angiosperm species towards the middle and upper parts of the Kachaike Formation, with the presence of monocolpate, tricolpate, tricolporoidate and tricolporate pollen, suggests an early-early middle Albian age for these parts of the unit, in agreement with the early Albian age proposed for its basal levels on the basis of dinoflagellates.</p

Nuevos registros palinológicos en los depósitos glacimarinos de la formación el paso (Serpukhoviano tardío-Bashkiriano), Precordillera Argentina: implicancias bioestratigráficas.

Se presenta nueva información palinológica para la Formación El Paso. Esta unidad aflora en el sector austral de la Sierra de Barreal, provincia de San Juan, Argentina (Cuenca Calingasta-Uspallata), y las asociaciones palinológicas se recuperaron de la parte media a superior de la sección. Contiene abundantes esporas trilete (75–907%) e hilate (1–57%), asignadas a Cyclogranisporites rinconadensis, Apiculatisporis variornatus, Raistrickia rotunda, Tricidarisporites gutii, Ahrensisporites sp. cf. A. cristatus, Cristatisporites stellatus, Indotriradites volkheimeri, Vallatisporites ciliaris y Psomospora detecta, entre otros. También, granos de polen subordinados (1,5–20%): Circumplicatipollis plicatus, Costatascyclus crenatus, Plicatipollenites sp. cf. P. malabarensis, Potonieisporites spp., Divarisaccus sp. cf. D. stringoplicatus. Acritarcos retrabajados y autóctonos (e.g., Cymatyogalea sp., Gorgonisphaeridium sp., Verhyachium sp.) y algas Zygnematalean (Tetraporina sp., Brazilea scisa) estan presentes con menos de 2,57%. Se propone una edad serpukhoviana tardía-bashkiriana y la correlación con la Subzona A de la Biozona Raistrickia densa-Convolutlspora muriornata (DM) para las asociaciones de la Formación El Paso.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 (1–57%) 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 (1.5–207%): 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 2.57% 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.Fil: Vergel, Maria del Milagro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Cisterna, Gabriela Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Rioja; ArgentinaFil: Sterren, Andrea Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones Paleobiológicas; Argentin