Palynofacies associated to hyperpycnite deposits of the Miocene, Cabo Viamonte Beds, Austral Basin, Argentina

• Autores: Quattrocchio, Mirta E.; Olivera, Daniela E.; Martínez, Marcelo A.; Ponce, Juan José; Carmona, Noelia Beatriz
• Año de publicación: 2018
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Ambientales y de la Tierra; Hyperpycnites; Palynofacies; Miocene; Cabo Viamonte Beds; Austral Basin; Argentina; Ciencias Ambientales y de la Tierra
• Institución: Universidad Nacional de Río Negro

Fil: Quattrocchio, Mirta E. Instituto Geológico del Sur-Consejo Nacional de Investigaciones Científcas y Técnicas CONICET), Departamento de Geología (UNS), San Juan 670, B8000ICN Bahía Blanca, Buenos Aires, Argentina
Fil: Olivera, Daniela E. Instituto Geológico del Sur-Consejo Nacional de Investigaciones Científcas y Técnicas CONICET), Departamento de Geología (UNS), San Juan 670, B8000ICN Bahía Blanca, Buenos Aires, Argentina
Fil: Martínez, Marcelo A. Instituto Geológico del Sur-Consejo Nacional de Investigaciones Científcas y Técnicas CONICET), Departamento de Geología (UNS), San Juan 670, B8000ICN Bahía Blanca, Buenos Aires, Argentina
Fil: Ponce, Juan José. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro; Argentina.
Fil: Carmona, Noelia Beatriz. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro; Argentina.
The Miocene deposits in the Punta Basílica locality, southernmost Argentina, are included within the Cabo Viamonte Beds, Cabo Domingo Group, in the Austral foreland basin of Tierra del Fuego province. The prograding clinoform systems were accumulated during a weak compressional tectonic regime that allowed the development of a narrow shelf. Paleoenvironmental reconstructions suggest that these clinoforms comprise two dominant architectural elements, channel-levee and lobe complexes, formed mainly by density hyperpycnal currents in outer shelf to depositional slope environments. The transitional and recurrent (vertical and lateral) alternation between sedimentary structures without rheologic boundaries associated with the co-occurrence of plant remains (Nothofagus) are diagnostic criteria for the recognition of hyperpycnites. This type of density fow typically transports large volumes of sediment and organic matter from proximal to deep-marine settings. Four palynofacies types were recognized in a cluster analysis. In general, the palynofacies show predominance of spores and pollen grains, tissues, cuticles, and spongy to fbrous amorphous organic matter (plant and/or freshwater to brackish algae derived), which refect diferent positions within the depositional system (e.g., levee-channel and lobe deposits). The co-occurrence of inshore (Batiacasphaera spp., Lingulodinium sp.) with relatively more oceanic (Operculodinium centrocarpum, Spiniferites spp.) dinofagellates is a strong indication that shallow-water assemblages have been displaced into deep-water settings. Due to the presence of Lingulodinium hemicystum (frst appearance data: 23.0 Ma.) and Pentadinium laticinctum (last appearance data: 11.6 Ma.) an age not older than Miocene and not younger than the Serravallian/Tortorian boundary for the Punta Basílica section is proposed.
The Miocene deposits in the Punta Basílica locality, southernmost Argentina, are included within the Cabo Viamonte Beds, Cabo Domingo Group, in the Austral foreland basin of Tierra del Fuego province. The prograding clinoform systems were accumulated during a weak compressional tectonic regime that allowed the development of a narrow shelf. Paleoenvironmental reconstructions suggest that these clinoforms comprise two dominant architectural elements, channel-levee and lobe complexes, formed mainly by density hyperpycnal currents in outer shelf to depositional slope environments. The transitional and recurrent (vertical and lateral) alternation between sedimentary structures without rheologic boundaries associated with the co-occurrence of plant remains (Nothofagus) are diagnostic criteria for the recognition of hyperpycnites. This type of density fow typically transports large volumes of sediment and organic matter from proximal to deep-marine settings. Four palynofacies types were recognized in a cluster analysis. In general, the palynofacies show predominance of spores and pollen grains, tissues, cuticles, and spongy to fbrous amorphous organic matter (plant and/or freshwater to brackish algae derived), which refect diferent positions within the depositional system (e.g., levee-channel and lobe deposits). The co-occurrence of inshore (Batiacasphaera spp., Lingulodinium sp.) with relatively more oceanic (Operculodinium centrocarpum, Spiniferites spp.) dinofagellates is a strong indication that shallow-water assemblages have been displaced into deep-water settings. Due to the presence of Lingulodinium hemicystum (frst appearance data: 23.0 Ma.) and Pentadinium laticinctum (last appearance data: 11.6 Ma.) an age not older than Miocene and not younger than the Serravallian/Tortorian boundary for the Punta Basílica section is proposed.