Recognizing drainage reorganization in the stratigraphic record of the Neogene foreland basin of the Central Andes

Abstract

Changes in drainage basin reorganization as preserved in the stratigraphic record have direct implications for the composition, organization, and scaling relationships of sedimentary systems. However, isolating the stratigraphic signature of drainage basin reorganization in response to tectonic and/or climatic drivers can be challenging. In the Neogene foreland basin of the southern Central Andes between 28°–31°S, the tectonically-controlled reorganization of basin catchment area has been cited as an important control on the basin stratigraphy. To resolve the signature of drainage basin reorganization in the Central Andean foreland, we conducted a basin-scale study integrating detailed sedimentology from four measured sections with multi-method provenance analysis to reconstruct foreland sediment routing pathways between 28°–31°S. Our regional synthesis suggests that the foreland basin has been connected by an axial sediment routing system since the early Miocene. Statistical analysis and graphical comparison using multidimensional scaling of new and published detrital zircon data from 45 samples resolves tectonically controlled changes in the catchment area in the late Miocene, including an eastward shift of the Andean drainage divide. This study provides the first evidence for expansion of the catchment area east of the basin draining the emerging basement-cored highlands of the Sierras Pampeanas. This study demonstrates that, when combined, provenance and detailed sedimentologic data sets provide a powerful tool to recognize and interpret drainage basin reorganization in the stratigraphic record and thus reconstruct the tectono-climatic and paleogeographic evolution of sedimentary systems.