Glaciomarine sequence stratigraphy in the Mississippian Río Blanco Basin, Argentina, Southwestern Gondwana. Basin analysis and paleoclimatic implications for the Late Paleozoic Ice Age during the Tournaisian

EZPELETA, M.; RUSTAN JJ; BALSEIRO D; DAVILA, F.M.

GEOLOGICAL SOCIETY OF LONDON SPECIAL PUBLICATION

GEOLOGICAL SOCIETY OF LONDON SPECIAL PUBLICATION

Año: 2020 vol. 177 p. 1107 - 1128

0305-8719

The Late Paleozoic Ice Age (LPIA) has been well-recorded in the Pennsylvanian ofGondwana. Nevertheless, little is known about the temporal and geographic dynamicsspecially during the early Mississippian. Here we report exceptional Tournaisiansiliciclastic marine stratigraphic sections from the Andean region of central Argentina(Río Blanco Basin). With ~1400 meters, these successions contain conspicuousglacigenic strata with age constraining from paleontological data and U/Pb detritalzircons. A variety of marine, glaciomarine, and fan-deltaic environments evidencerelative sea-level variations mainly associated with tectonism and repetitive cycles ofglacial activity. Provenance analysis indicate a source from the Sierras Pampeanasbasement (Eastern). Fifteen sequences were grouped into three depositional models:1) Low System Tracts (LST) to Transgressive System Tracts (TST) and finally HighSystem Tracts (HST) with glacial influence, 2) TST-HST sequences unaffected byglacial ice and 3) LST-TST-HST sequences interpreted as sea-level fall not related withice. The glacial evidences indicate that the oldest Mississippian glacial stage of theLPIA in southwestern Gondwana is mid Tournaisian. In contrast with previousdescriptions of Gondwanan coeval glacial records, our sequence analysis confirms acomplex hierarchical climatic variability, instead of a single episode of ice advance andretreat.