Macrofloristic assemblage of the Paraná Formation (Middle-Upper Miocene) in Entre Rios (Argentina).

ANZÓTEGUI, L Y P. ACEÑOLAZA

NEUES JAHRBUCH FUR GEOLOGIE UND PALAONTOLOGIE-ABHANDLUNGEN

E. Schweizerbart`sche Verlagsbuchhandlung

Lugar: Stuttgart; Año: 2007 vol. 24

0077-7749

Paraná Formation represents the marine ingression of Middle-Upper Miocene that invaded the Pampean plain and parts of Argentinean Mesopotamia. In its outcroppings, an abundant fossil fauna and plant remains (palynomorphs, logs, foliar impressions and phytoliths) have been recognized. In Villa Urquiza locality (Entre Ríos Province), the outcropping strata are constituted by white sands intermingled with pure clays, gray to grayish-green, with abundant diagonal and flat structures with paleochannels filled with clays. In this study, foliar impressions such as Myrciophyllum paranaesianum sp. nov.; Laurophyllum sp. (Lauraceae), and Schinus aff. terebinthifolia (Anacardaicaeae) are described. The assignment of Laurophyllum and Myrciophyllum and the existence of xerophytic forests are discussed. Taking into account both the habit and habitat of present plant species related to the fossil material, it is concluded that in high altitude zones of the marine environment in Paraná Formation there existed highland forests with Podocarpaceae and Araucariaceae. It is considered that these species integrated an heterogeneous environment with highlands and flooded lowlands, as part of the Seasonal Dry Neotropical Forest. The climate would have been warm and humid and among the environmental units; there were hydrophylous and mesophylous forests, marshy environments, lentic and lotic aquatic communities. Considering plant leaves impressions and the communities they formed, vegetation of the Paraná Formation is comprised in the Neotropical Paleophytogeographic Province. Key words. Leaves, Macroflora, Middle Miocene, Paleocommunity, Entre Ríos, Argentina.