Environmental and climatic proxies for the Cañadón Asfalto and Neuquén basins (Patagonia, Argentina). Review of Middle to Upper Jurassic continental and near coastal sequences.

VOLKHEIMER W,; QUATTROCCHIO M.E.; CABALERI N.; NARVÁEZ, P.L.

REVISTA BRASILEIRA DE PALEONTOLOGIA

SOC BRASILEIRA PALEONTOLOGIA

Lugar: Porto Alegre; Año: 2015 vol. 18 p. 71 - 82

1519-7530

ABSTRACT - In this review we include several proxies (sedimentology, palynology, 31 invertebrates) from the Cañadón Asfalto and Neuquén basins, to infer the environments 32 and regional climatic context during the Middle to Late Jurassic of Patagonia. In central 33 Patagonia, early in the Middle Jurassic, and associated with a magmatic arc, began the 34 sedimentary filling of Jurassic continental sub-basins in the Cañadón Asfalto Basin. 35 Lacustrine and fluvio-deltaic sediments, bearing a continental Middle Jurassic palynobiota, 36 correspond to the Las Chacritas Member, while the sediments and palynobiota from the 37 Late Jurassic Puesto Almada Member (both in the Cañadón Asfalto Fm) indicate a 38 palustrine wetland subenvironment immersed within an arid macroenvironment. 39 Paleoinvertebrates (conchostracans and sponges) of this Formation suggest wet-dry cycles 40 in the water bodies they inhabited. The sedimentological information together with the 41 continental and coastal palynomorph assemblages of the back arc Neuquén Basin, allowed 42 distinguishing a complete regressive-transgressive sequence for the Middle Jurassic Lajas 43 Formation. For the Late Jurassic in this basin, the thick gypsum and anhydrite deposits of 44 the evaporitic coastal Auquilco Formation, correlate with extended deposits of eolian 45 sandstones corresponding to the Botucatú paleodesert, and a saltmarsh environment is 46 inferred from the palynoflora. The palynologic associations from both basins indicate a 47 regional warm climate with seasonal aridity. Climatic conditions would have been drier in 48 the continental interior (Cañadón Asfalto Basin), with strongly seasonally distributed 49 temperatures, and moister in the western coast of the continent (Neuquén Basin), during 50 the marine transgressions