IANIGLA   20881
INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
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, N.G.; BENAVENTE, C.A.; MONFERRAN, M.D.; NARVÁEZ, P.L; VOLKHEIMER, W.; GALLEGO, O.F.; DO CAMPO, M.D.
Revista:
SEDIMENTARY GEOLOGY
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2013 vol. 296 p. 103 - 103
ISSN:
0037-0738
Resumen:
Six facies associations are described for the Puesto Almada Member at the Cerro Bandera locality (Fossati subbasin). They correspond to lacustrine, palustrine, and pedogenic deposits (limestones); and subordinated alluvial fan, fluvial, aeolian, and pyroclastic deposits. The lacustrine?palustrine depositional setting consisted of carbonate alkaline shallow lakes surrounded by flooded areas in a low-lying topography. The facies associations constitute four shallowing upward successions defined by local exposure surfaces: 1) a Lacustrine?Palustrinepedogenic facies association with a ?conchostracan??ostracod association; 2) a Palustrine facies association representing a wetland subenvironment, 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 source 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 planktonic 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.fluvial, aeolian, and pyroclastic deposits. The lacustrine?palustrine depositional setting consisted of carbonate alkaline shallow lakes surrounded by flooded areas in a low-lying topography. The facies associations constitute four shallowing upward successions defined by local exposure surfaces: 1) a Lacustrine?Palustrinepedogenic facies association with a ?conchostracan??ostracod association; 2) a Palustrine facies association representing a wetland subenvironment, 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 source 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 planktonic 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.