Resumen de Estudio bioestratigráfico integrado del perfil La Horqueta (límite Aptiano-Albiano), lago Cardiel, Patagonia, Argentina
Francisco Medina, Sergio Archangelsky, Verónica Guler, Ana Archangelsky, Orlando Cárdenas
Integrated biostratigraphical study of La Horqueta section (Aptian-Albian boundary),Cardiel lake, Patagonia, Argentina. La Horqueta at Cardiel lake is a classical section in Santa Cruz provincewhere marine invertebrates include ammonites of the Aptian-Albian transition. New collections at this siteyielded palynological remains from several horizons in both Río Mayer Formation (latest Aptian) and PiedraClavada Formation (earliest Albian). Marine dinoflagellate cysts are found in the lower part of the section; theyagree with an Aptian to earliest Albian age suggested by ammonites. Statistical counts of six palynologicalgroups show the dominance of the conifer family Cheirolepidiaceae in the Río Mayer Formation coinciding withthe presence of dinoflagellate cysts and the gradual increase of pteridophitic spores and saccate pollen, mainlyof the family Podocarpaceae in the upper Piedra Clavada Formation. Angiosperm pollen is present throughoutthe section although it is more significant in the upper Piedra Clavada Formation where several new types havetheir first appearance (tricolpate, tricolporoidate and other types). Most palynological taxa are found across thewhole section and many are known to occur in other units cropping out in this area, as the Baqueró Group(Early Aptian) or Kachaike Formation (Mid-Late Albian). Only few selected and probably significant specieshave been found to be of a possible biostratigraphic value and their distribution along the section is shown in achart.
