Taphonomic and paleoenvironmental reconstruction of the Triassic lacustrine system from the Agua de la Zorra Formation, Cuyana Basin, Mendoza, Argentina

ADRIANA C. MANCUSO; CECILIA A. BENAVENTE; TOMÁS E. PEDERNERA; EDUARDO G. OTTONE

General Roca

Congreso; 11° Congreso de la Asociación Paleontológica Argentina; 2016

Asociacion Paleontologica Argentina (APA)

Taphonomic studies and paleoenvironmental analysis have a central role in the interpretation and reconstruction of extinct macroflora paleocommunities. The Agua de la Zorra Formation (Triassic) crops out at the Paramillos de Uspallata locality (Cuyana Basin, Mendoza,Argentina) and represents a deltaic-lacustrine system. This work presents the paleoenvironmental reconstruction of this unit using sedimentological and taphonomic data provided by vegetal remains. Fossil plant remains were collected and identified and their taphonomic attributes were observed. Six taphofacies were identified and defined by the lithology of the rocks and taphonomic attributes like density, packing, sorting and orientation of the fossils were recorded. The taphofacies represent different sedimentary subenvironments within the deltaic-lacustrine system. Four of the taphofacies are characterized by siltstone deposits and represent a proximal-distal gradient from the margin to the prodelta. The other two taphofacies are associated with mudstones and represent the lake center. One of them shows more deltaic influence (mudrock with diffuse lamination) and articulated vegetal remains; and the other has less evidence of deltaic influence (massive mudstone) with disarticulated and broken relative smaller fragments of fossil plants. In the Agua de la Zorra paleolake were identify two depositional subenvironments, one with more input of sediment and oxygenated, linked to a delta; and another one dominated by anaerobic conditions linked to the center of the water body. *Subsidiado por PICT 2013-0805-(A.C. Mancuso) and PIP 00709 (E.G. Ottone).