First Report of a Maastrichtian Palynoflora from the Golfo San Jorge Basin, Central Patagonia, Argentina

Abstract

This paper reports on the biostratigraphic, paleobiogeographic and paleoecologic aspects of palynoflora recovered from sedimentary rocks preliminarily assigned to the Lago Colhué Huapi Formation, in the Golfo San Jorge Basin. The present palynological assemblage includes Maastrichtian marker species of the austral Proteacidites/Nothofagidites Province such as Quadraplanus brossus and Tubulifloridites lilliei. Typical species of the Maastrichtian paleotropical Palmae Province, Buttinia andreevi and Gabonisporis vigourouxii, are also recognized in the palynoflora. These facts indicate the mixed character of the paleoflora and the prevalence of transitional climatic conditions at the paleolatitude of the Chubut Province in the uppermost Cretaceous. The palynoflora composition suggests the local existence of a warm and low energy freshwater body.

Salviniales from the Late Cretaceous of the Golfo San Jorge Basin

“…6H, I), which probably represents the pollen of extant Arecaceae (Nypa-type). A similar palynological assemblage was recently reported from another section at the headwaters of the Río Chico (Vallati et al, 2016). The aquatic community of the lower bed studied at Cerro de los Fragmentos (CF1 in Fig.…”

“…This unit overlies the Bajo Barreal Formation and underlies the Laguna Palacios Formation or the Salamanca Formation, according to its geographic position in the basin. The Lago Colhu e Huapi Formation shows gradational top and basal contacts and occasionally an erosion surface (local unconformity) separates this unit from the Salamanca Formation (Casal et al, 2015;Vallati et al, 2016). In addition, at the studied locality (Fig.…”

“…At its type locality, the Lago Colhu e Huapi Formation, represents fluvial conditions of deposition with high-sinuosity channel systems and wide well-drained floodplains (Allard and Casal, 2013;Casal et al, 2015). This unit includes remains of titanosaurids, hadrosaurids and rare theropods , as well as plant remains (palynoflora, mesofossils and leaves) at the uppermost beds (Vallati et al, 2016;this paper).…”

“…Stratigraphic horizon. Maastrichtian, based on a palynoflora studied in a nearby exposure at the same locality (Vallati et al, 2016). Derivation of name.…”

“…Salvinialean fossil remains consisting of massulae with septate glochidia, a single megaspore apparatus of Azolla and microspores of Gabonisporis vigourouxii Boltenhagen, 1967 have been reported from the uppermost part of the Lago Colhu e Huapi Formation from a section outcropping at the headwaters of the Río Chico (Vallati et al, 2016). This palynoflora, included significant biostratigraphic markers of the upper Maastrichtian such as Quadraplanus brossus Stover and Partridge, 1973 and Tubulifloridites lilliei (Couper) Farabee and Canright, 1986. In the present paper, we report additional aquatic plant material of the Salviniales from a nearby section at the headwaters of the Río Chico.…”