163-A 2.3

The objective of the proposal is to understand the evolution of the Andean foreland system in its initial stage in the NOA (Northwestern Argentina) region. On the basis of the present state of knowledge of the Paleogene foreland record, some questions emerge regarding the application of the traditional models of deformation-sedimentation in this area. Thus the main hypothesis to test is that the Andean Paleogene deformation-sedimentation occurred simultaneously in the Puna and in the western portion of the Eastern Cordillera, evolving under a broken basin style and without a systematic orogenic wedge migration. The features of the Precambrian- early Paleozoic basement and the distribution and geometry of mainly normal faults of the Cretaceous rift played an important role in the style and in the geometry of the broken foreland system. Considering these two points, the specific objectives are to reconstruct the paleogeography and paleoenvironments of the sedimentary basins, and to model the kinematic of structures and style of deformation, and volcanism related with the Andean orogenic system.
To reach these goals, two W-E trending transects along the northern Puna and the Eastern Cordillera (from Aguilar range to the Quebrada de Humahuaca, including also the Coranzulí Volcanic Complex farther west) and southern Puna and Eastern Cordillera (from the Arizaro salar to the Lerma valley) were selected. Along these transects there are found interesting sedimentary sequences, structures, and volcanic deposits. In each locality we are going to perform detail mapping, stratigraphic profiles, sedimentary studies (facies association, spatial distribution of environments and provenance), volcanological studies and structures measurements and reconstruction. With the integration of the results of the different lines of investigation we will propose a model of spatio-temporal variation of the foreland system in this part of the Andes.