. Mineralogy, Petrology and Geochemistry of Siliciclastic Rocks (Tordillo Fm, Upper Jurassic Fluvial Systems, Neuquén Basin, Argentina).

SPALLETTI, L.; MATHEOS, S. D.; COLOMBO, F.; QUERALT, I.

Coimbra (Portugal)

Congreso; XXIII European Meeting International Association of Sedimentologists; 2004

IAS

A number of stratigraphic sections allow us to define different lithofacies by means a primary sedimentary structures and rock bodies´ stratigraphic geometries. The facies denomination is un adaptation (Spalletti, 200 1) of the classical Miall´s nomenclature (Miall, 1978). There are some stratigraphic logs displaying their lithofacies distribution and the main paleocurrent vectors. The facies assemblages were delined by means of the spatial relationships between minor rock bodies, which are physically, and genetically rc1ated (Spalletti, 2001). The delined facies assemblages enabled lhe implementation of a conceptual model for the regional distribution of the main Kimmeridgian depositional systems´ of the Austral Neuquen basin in the studied area (Spallctti&Colombo, 2003). Tordillo formation was interpreted as an ephemeral fluvial system developed under a generalized phase of arid to semiarid climate. The volcaniclastic nature of the Tordillo deposits and the palaeocurrent trends suggest a positive topography of the land located southwards (Dorsal de Huincul). The uplift of this structure was intense and active at the time of the deposition of the Tordillo Formation.