Evolutionary dynamics of the Holocene alluvial fan system of Las Carreras Valley (Sierras Pampeanas, NW Argentina)

Sampietro-Vattuone, María Marta ; Peña-Monné, José Luis ; Báez, Walter Ariel

Resumen: The Las Carreras Valley, part of the Tafí Valley in Northwestern Argentina, offers a detailed geomorphological record of Holocene evolution within a tectonic intermontane depression in the Sierras Pampeanas. This study aimed to examine the evolutionary morphology of the main alluvial fans along the western edge of the Las Carreras Valley, at the piedmont of the Sierra de Aconquija. Through geomorphological mapping, stratigraphic profiling, and chronological analyses, this study examines the complex interplay between sedimentary processes, tectonic activity, climatic variability, and human occupation across the three principal alluvial fans: Rodeo, Las Carreras, and Los Alisos. Key findings highlight the influence of Pleistocene-Holocene glacial phases (Younger Dryas, Pre-Boreal Oscillation, Neoglacial Cold Phase) on the formation of Unit H1 (13–4.2 kyr BP) and the dominance of Unit H2 (4.2 kyr BP–600 BP) across fan surfaces. Late Holocene transformations include significant basin captures —such as the Muñoz River headwaters by the Los Alisos River basin— avulsion processes, and neotectonic activity linked to the Las Carreras double fault. These geomorphological changes shaped alluvial fan dynamics, altering drainage networks, fan morphologies, and sedimentary deposits. Stratigraphic profiles reveal Pleistocene deposits as foundational layers, overlain by Holocene units, with volcanic ash markers (V1, V0) serving as chronological indicators. The geomorphology further correlates with human settlement patterns, notably the Tafí culture (360 BCE–1000 CE), whose agricultural adaptations relied on alluvial fan resources. This comprehensive analysis underscores the critical role of tectonic, fluvial, and climatic processes in shaping alluvial fan systems. It provides a framework for assessing environmental risks, land-use strategies, and conservation efforts in tectonically active and semiarid regions.

Idioma: Inglés

DOI: 10.1016/j.catena.2026.109851

Año: 2026

Publicado en: Catena 264 (2026), 109851 [15 pp.]
ISSN: 0341-8162

Tipo y forma: Article (Published version)