Xiphosurid trackways in a Lower Cretaceous tidal flat in Patagonia: Palaeoecological implications and the involvement of microbial mats in trace-fossil preservation

The Agrio Formation (Early Cretaceous) in the Neuquen Basin.- The marine deposits of the Agrio Formation have an ample distribution in the outcrop areas and in the subsurface of the Neuquen Basin. The knowledge of this record, that covers a time span of about 7 my, is essential to better understand the development and evolution of the processes of deposition and the faunistic evolution of the Cretaceous in the Neuquen Basin. This paper presents a synthesis on the geologic knowledge of the Pilmatue (lower) and Agua de la Mula (upper) members of the Agrio Formation. A revision of the main stratigraphical studies is presented, as well as the outstanding contributions on palaeontology, biostratigraphy and chronology. Special attention is paid to geological correlation, in particular with the units located towards the marginal eastern and southern sectors of the Neuquen Basin. Siliciclastic and carbonate facies are described and interpreted in terms of main processes of accumulation. Based on sedimentological and palaeontological information the most recent conceptual palaeoenvironmental and palaeoecological models are presented. A revision on sequence stratigraphy, including key surfaces, hierarchies and controls, are also discussed. Finally, the potencial research topics that would contribute to a better understanding of the Upper Valanginian – Early Barremian marine record of the Neuquen Basin are suggested.

La formación agrio (cretácico temprano) en la cuenca neuquina

Sedimentological and ichnological characterization of muddy storm related deposits: The upper Hauterivian ramp of the Agrio Formation in the Neuquén Basin, Argentina

. This study includes a thorough systematic analysis of the ichnological record in the uppermost section of the Agua de la Mula Member of the Agrio Formation (Mendoza Group) in the Neuquen Basin (Argentina). The Bajada del Agrio section represents an environment evolving from marine to marginal-marine. Five main facies were defined: (1) an oolitic-skeletal bar; (2) transgressive pelites and coquinas (bioclastic conglomerates); (3) progradational coarsening-upward sandstones; (4) heterolithic deposits; and (5) heterolithic and carbonatic deposits. Fluctuating salinity and/or hypersalinity is inferred in the open tidal-flat deposits (facies 4). Sixteen ichnotaxa were identified and three types of trace fossils were described using open nomenclature because of the poor preservation of the material. Three ichnoassemblages are described. The section yielded trace fossils of callianasid decapods, palaeotaxodont bivalves, annelids and small tetrapods. Paleoenvironmental information drawn from trace fossi...

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Ichnology of marginal marine facies of the agrio formation (lower cretaceous, neuquén basin, argentina) at its type locality

Tectonic repetitions of the Early Cretaceous Agrio Formation in the Chos Malal fold-and-thrust belt, Neuquén Basin, Argentina: Geometry,kinematics and structural implications for Andean building

Palynofacies analysis and palynology of the Agua de la Mula Member (Agrio Formation) in a sequence stratigraphy framework, Lower Cretaceous, Neuquén Basin, Argentina

Fil: Lazo, Dario Gustavo. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geologicas; Argentina

Maria Veronica Guler

Papers

Palynofacies analysis and palynology of the Agua de la Mula Member (Agrio Formation) in a sequence stratigraphy framework, Lower Cretaceous, Neuquén Basin, Argentina

Bioestratigrafía integrada de la formación agrio en su localidad tipo, cretácico temprano de cuenca neuquina