Paleoenvironmental interpretation of the deposits of the Saldeño Formation (Upper Cretaceous) in the High Cordillera of Mendoza (Argentina)

Abstract

The Saldeño Formation consists of up to 250 m of siltstones, sandstones, conglomerates and limestones located in almost a continuous belt from the Mesón de San Juan (33° 33´ SL) up to Laguna del Diamante area (34° 06´ SL), in the high Cordillera of Mendoza. A paleoenvironmental interpretation has been made for these deposits. The lower section of the unit was deposited in an alluvial fan environment and it is not genetically related with the uppermost sections. The analyses of the middle and upper section of the unit suggested that the deposition took place in a transitional environment from a muddy distal fluvial system to a restricted shallow marine environment with intervals laid under brackish conditions and tidal influence. Marine fossils including bivalves, gastropods, fishes and lobsters were discovered for first time on the upper section of this unit. However, the maastrichtian age of the Saldeño Formation were established with nannofossils and micropalinological analyses. These marine deposits show strong evidences of having been laid by an Atlantic transgression.