LOS MINERALES ARCILLOSOS EN LAS ARENISCAS DE LA FORMACIÓN HUINCUL: SU ROL EN LA DELIMITACIÓN DE UN FRENTE REDOX INDUCIDO POR LA MIGRACIÓN DE HIDROCARBUROS. DORSO DE LOS CHIHUIDOS, CUENCA NEUQUINA

RAINOLDI A.L.; IMPICCINI A.; FRANCHINI M.; PONS M.J

San Juan

Congreso; XI Congreso de Mineralogía y Metalogenia; 2013

UNSJ, AMA

The Huincul Formation sandstones are exposed along the extended flanks of Los Chihuidos High, a Tertiary structure located in the central part of the Neuquén Basin. The Huincul Formation is the second of the seven units which conforms the Neuquén Group, a thick continental red bed sequence deposited in the Cenomanian-Campanian during the continentalization of the Neuquén Basin. Progressive burial diagenesis generate changes in the original red sandstone resulting in a colorful facies arrangement where the original red sandstones are interbedded with bleached sandstones and the contact between them is given by the presence of gray and minor brown sandstones. A visual distinction between the facies is internally reflected in variations in mineralogy, major oxides and trace elements and porosity. Compared to the red beds, bleached sandstones do not contain hematite coatings, present an increase in the secondary porosity, and contains secondary minerals such as smectite (montmorillonite) and late poikilotopic calcite. The Cu-montmorillonite and V-Cu mixed-layer Mg-chlorite-smectite with minor V-bearing hematite which characterize the gray and brown sandstones, mark the peneconcordant and laterally continuous level of the oxidized-reduced compartments, outlining the redox front in the system