Late Cretaceous ? Cenozoic Biostratigraphy and Palaeoenvironmental reconstruction of the Salado and Punta del Este Basins, sw Atlantic Ocean

JUAN PABLO PÉREZ PANERA; DIANA RONCHI; GLADYS ANGELOZZI; LYDIA CALVO MARCILESE; LEONARDO TÓRTORA; NORBERTO CALARAMO; JUAN PABLO LOVECCHIO; PEDRO KRESS FRIELING

GENERAL ROCA

Congreso; CONGRESO DE LA ASOCIACIÓN PALEONTOLÓGICA ARGENTINA; 2016

ASOCIACIÓN PALEONTOLÓGICA ARGENTINA

Foraminifer and calcareous nannofossil data revision and new studies on ten boreholes fromSalado and Punta del Este basins, let a synthesis of its biostratigraphy and sedimentary cycles.Microfossil assemblages and markers of local interest were defined and correlated withseismic data when possible. Within the Late Maastrichtian ? late Miocene, three majorsedimentary cycles were identified. A Maastrichtian transgression indicates the beginning ofmiddle to outer shelf conditions that last until Danian. A second sedimentary cycle startedwith a regressive sequence in the Middle ? Late Paleocene, identified by marine to marginalmarine, and continental to marginal marine Eocene deposits in Punta del Este and Saladobasins, respectively. The sedimentary infill of the second cycle is bracketed by two hiatusspanning Middle Paleocene ? early Eocene at the base and late Eocene ? Oligocene at the top.Eocene age is interpreted on the basis of nannofossil markers found in Punta del Este. Duringthe Early Miocene, onset of a third sedimentary cycle is marked by a regional transgressionthat prevailed until the Miocene. Early Miocene foraminifers are very diverse including manyplanktonic species, with lower diversity and benthic forms in the late Miocene, whichindicates a progressive shallowing of the basins by that time. Nannofossil assemblages arealso more diverse and present low latitude affinity during the early and middle Miocene,which is interpreted as a record of the MMCO. Late Miocene assemblages become lessdiverse and are dominated by cold-water affinity species. *Proyectos I+D+i 620 (Y-TEC) y PICT 2013 - 0771