Sedimentary Responses to Tectonic and Climatic Forcing: A High-Resolution, Integrated Sedimentological-Geochemical Study in Terrestrial Foreland Deposits (Mendoza, Argentina)

Abstract

Numerous studies relate foreland-basin infill to allogenic forcing, but to date only a few have been able to clearly disentangle the relative roles of tectonics and climate on long-term deposition. Here we present preliminary observations on the continental sedimentology and stratigraphy of the Central Argentinian Foreland. The basin infill records local environmental changes from the late Oligocene to the Quaternary, during active Andean orogeny. The Mariño Formation comprises a large part of the basin infill, dating from ~15.7 to 12.0 Ma and extending over almost 1100 m in stratigraphy. The basal part is characterized by the intercalation of aeolian and fluvial deposits, followed vertically by the stacking of fluvial deposits with highly differentiated facies associations and architectures. This stratigraphic picture developed during the uplift of the Principal Cordillera suggests the interaction of different allogenic controls in the region. This project aims to provide a detailed reconstruction of paleoenvironmental dynamics and to unravel the relative roles of climate and tectonics through a high-resolution, integrated compositional and sedimentological analysis of the Mariño Formation. The main objectives are: to detect geochemical signatures of allogenic controls; to track changes in sediment provenance and relative information on magmatism and exhumation in the uplifting Andes; and to recognize the effects of different allogenic drives on sedimentary processes and local environmental changes. Our approach consists of high-resolution mineralogical and petrographical study using both conventional approach and automated QEMSCAN technology, heavy-minerals analysis, geochemistry, radiogenic isotope analysis, U-Pb and fission-track dating of detrital zircons. The exceptional lateral exposure and the possibility to develop stratigraphic correlations calibrated with quantitative analytical approaches will constrain the relative role of different allogenic processes and offer insights for understanding similar sedimentary complexes in the subsurface. Exploration and extraction of energy resources is increasingly reliant in the detailed characterization of sedimentary reservoirs. Besides providing an extensive outcrop analogue for the characterization and prediction of subsurface reservoirs, this project represents an important, ground-based test of mineralogical and geochemical methods for reservoir correlation and evaluation.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015