Depositional model of Pliocene–Holocene Fluvial Systems and Alluvial Fans in the southern Pampean Range (Córdoba-Argentina)

Abstract

The limited sedimentary successions preserved in intramontane valleys, together with the stratigraphic complexity of piedmont deposits in the southern sector of the C´ordoba Ranges, remain poorly documented. The Alpa Corral/Seco basin (Comechingones Range and eastern piedmont) provides a suitable case study to address these issues. An integrated approach combining detailed facies analysis, paleocurrent data, and correlations with lithostratigraphic units recognized in the region, allows for the reconstruction of the braided fluvial systems developed in the intramontane valley. These systems contribute to the construction of alluvial fans in the piedmont, which record alternating episodes of eolian activity. The basin evolution occurred under climatic and tectonic controls. The tectonic processes influenced the development of the intramontane depression, as well as the accommodation and the generation of structural discontinuities and deformation. However, its influence was subordinate but continuous through time. Conversely, the climatic conditions represented the main control on sediment supply, sequence architecture, facies distribution, and depositional system dynamics. This is reflectedin marked Pliocene–Holocene variability, where warm and humid periods promoted enhanced erosion and sediment transport processes and expansion of the drainage network. In contrast, arid and cold periods produced the fluvial system contracted, alluvial fans developed along the piedmont, coexisting with sheet-flow processes, and predominant the eolian deposition. This study improves the understanding of the Pliocene–Holocene sedimentary successions and provides a framework to characterize the geological record of these modern systems.