The section of the Sierra de la Ventana Range

SICCARDI, ARÓN; MOREL, EDUARDO ; CINGOLANI, CARLOS ALBERTO; URIZ, NORBERTO JAVIER

Planet Earth - In deep time. Palaeozoic Series. Devonian & Carboniferous

Schweizerbart'sche Verslagsbuchhandlung

Lugar: Stuttgart; Año: 2016; p. 206 - 207

The Sierra de la Ventana range lies in the southwest of the Buenos Aires Province towards the southern edge of the Río de la Plata craton. It is characterised by the Palaeozoic siliciclastic sequence that is superposed to the Neoproterozoic basement. Tectonically the range conforms with a Permian-Triassic fold- and thrust-belt of an East structural vergence. The Palaeozoic sequence is formed by three groups known as Curamalal (Cambrian-Orodovician), Ventana (Silurian-Devonian) and in unconformity, the Pillahuincó (Carboniferous-Permian). The Pillahuincó Group shows the presence of diamictites with the galacial event on Gondwana. The Ventana Group (1300 , thick) includes in its upper part the Lolén Formation that is composed mainly of lithic feldspar,; quartzose and micaceous sandstones; wackes and interbedded black shales, with shallow marine water sedimentary structures such as: tabular beds; cross-beddingg; thin lamination and ripple marks. The unit records in the lower section deformed marine invertebrates (brachiopods, bivalves) assigned to the Emsian and correlated with the Bokkeveld Group from South Africa and other outcrops in Gondwana that characterised the Malvinokaffric realm. In the upper section of the unit, the Lolén Formation record continentalisation processes with Middle Devonian lycopsid plants from high southern palaeolatitudes of Gondwana. The sedimentary and biostratigraphic features represent a shallow marine clastic platform with diverse source area.