Mega-geomorphology of Tafí del Valle-Aconquija, Tucumán

Abstract

In the Aconquija mountain range, the Cenozoic sequence begins with a fine to medium conglomerate of light gray to yellowish pink gray color, remanent of the erosion during the general uplift of the mountain ranges. The mid-upper Tertiary sedimentary sequence is preserved on the sides of the Aconquija mountain range, in valleys formed by extensive tectonical processes through eastward dipping north-south strike faults. At the nortwest end of the Aconquija mountain range (El Infiernillo, Los Corrales, Las Ánimas) the Los Corrales syncline product of the Aconquija fault, which uplifted the mountain range, is formed with the upper sequence of the Santa María Group. The conglomerates of the Lomitas Pegadas Formation assigned to the Pleistocene would have formed extensive downward sloping surfaces filling almost all the Tafi Valley, extending throughout the eastern side of the Aconquija-Cumbres Calchaquíes and reaching the Tucumán basin. Over this great downward slope, and partialy over its bed rock, loess or loess-like sediments of the Tafí del Valle Formation were settled. These Quaternary deposits are dislocated by subsequent differential tectonic uplift which reactivated the pre-existing regional faults. The Aconquija mountain range was separated from the Cumbres Calchaquíes during the Pleisocene by the action of normal NW striking faults with horizontal displacement components, as a result of extensional and transpressive processes.