INVESTIGADORES
CABALERI nora Graciela
artículos
Título:
Sedimentology and palaeontology of the Upper Jurassic Puesto Almada Member (Cañadón Asfalto Formation, Fossati sub-basin), Patagonia Argentina: Palaeoenvironmental and climatic significance
Autor/es:
CABALERI, NORA G.; BENAVENTE, CECILIA A.; MONFERRÁN, M. D.; NARVAEZ, P. L.; VOLKHEIMER, W.; GALLEGO, OSCAR F.; DO CAMPO, M.
Revista:
Sedimentary Geology
Editorial:
Elsevier
Referencias:
Lugar: Londres; Año: 2013 vol. 296 p. 103 - 121
ISSN:
0037-0738
Resumen:
Six facies associations are described for the Puesto Almada Member at the Cerro Bandera locality (Fossati sub-basin). They correspond to lacustrine, palustrine, and pedogenic deposits (limestones); and subordinated alluvial fan, fluvial, aeolian, and pyroclastic deposits. The lacustrine-palustrine depositional setting consists of carbonate alkaline shallow lakes surrounded by flooded areas in a low-lying topography. The facies associations constitute four cycles defined by local exposure surfaces: 1) a shallowing upwards succession of Lacustrine-Palustrine-Pedogenic facies with a conchostracan-ostracod association; 2) a Palustrine facies association representing a wetland sub-environment, and yielding conchostracans, body remains of insects, fish scales, ichnofossils, and palynomorphs (cheirolepidiacean species and ferns growing around water bodies, and other gymnosperms in more elevated areas); 3) an Alluvial fan facies association indicating the area of sediment supply; and 4) a Lacustrine facies association representing a second wetland episode, and yielding conchostracans, insect ichnofossils, and a palynoflora mainly consisting of planctonic green algae associated with hygrophile elements. The invertebrate fossil assemblage found contains the first record of fossil insect bodies (Insecta-Hemiptera and Coleoptera) for the Cañadón Asfalto Formation. The succession reflects a mainly climatic control over sedimentation. The sedimentary features of the Puesto Almada Member are in accordance with an arid climatic scenario across the Upper Jurassic, and they reflect a strong seasonality with periods of higher humidity represented by wetlands and lacustrine sediments.