AN INTEGRATED MODEL OF HYPERPYCNITES RELATED TO PALYNOFACIES. A CASE OF STUDY: CABO VIAMONTE BEDS, CABO DOMINGO GROUP, AUSTRAL BASIN

QUATTROCCHIO MIRTA ELENA; OLIVERA, DANIELA E.; MARTÍNEZ, MARCELO; PONCE JUAN JOSÉ

La Plata

Simposio; XVI Simposio Argentino de Paleobotánica y Palinología; 2015

Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata; Asociación Latinoamericana de Paleobotánica y Palinología; Fundación Museo de La Plata ?Francisco Pascasio Moreno"

The Punta Basílica deposits are included within the Cabo Viamonte Beds, Cabo Domingo Group, and were formed during a weak compressional tectonic regime that allowed the development of prograding clinoform systems in the Austral foreland basin of Tierra del Fuego. Paleogeographic reconstructions suggest that the Cabo Viamonte Beds comprise two dominant architectural elements, channel-levee and lobe complexes, formed mainly by density hyperpycnal currents in outer shelf to deep-marine environments. The objective of this study was to establish the relationship between the sedimentary environment and the palynofacies types, and thereby to propose an integrated depositional model. Four Palynofacies Units were recognized after the Cluster Analysis and Principal Components Analysis. The palynofacies show predominance of spores and pollen, tissues, cuticles, and spongy and fibrous amorphous (plant derived), which reflect a continental input to the basin. The co-ocurrence of inshore (Batiacasphaera spp., Lingulodinium sp.) with oceanic (Operculodinium centrocarpum, Spiniferites spp.) dinoflagelates is a strong indication that shallow-water assemblages have been displaced into a deep-water setting. These observations together with the co-occurrence of plant remains (Nothofagus) and the transitional and recurrent sedimentary structures without rheologic boundaries are diagnostic criteria for the recognition of hyperpycnite deposits. This type of density flows typically transports important volumes of sediment and its palynological content from proximal to deep marine settings. Due to the presence of Lingulodinium hemicystum (FAD: 23,0 Ma.) and Pentadinium laticinctum (LAD: 11,6 Ma.) it is proposed an age not older than Miocene and not younger than the Serravalian/Tortorian boundary for the Punta Basílica section.