STRATIGRAPHIC RECORDS OF FLUVIAL-FAN PROGRADATION: RECENT INSIGHTS AND A MODEL FOR ARID SETTINGS BASED ON THE OLIGO-MIOCENE OF THE CENTRAL ARGENTINIAN FORELAND

VENTRA, D.; MOSCARIELLO, A.; HUNGER, G.; VEIGA, G.D.

Conferencia; 5th International Conference on Alluvial Fans; 2015

Recent debates on the importance of fluvial (mega)fans for the infill of continental sedimentary basins areleading to a reconsideration of genetic relationships between stratigraphic units previously interpreted to resultfrom generic changes in allogenic forcing. Hypotheses on the dominance of fluvial-fan deposits in continentalrecords are followed by the inference that very thick facies successions of dominantly alluvial origin (butfrequently including facies associations from different depositional systems) may relate to long-term fanaggradation / progradation, ideally reflected by vertical stacking of relatively coarse clastic facies associationsfrom proximal, high-energy fluvial environments over relatively fine-grained facies associations representingdistal, low-energy alluvial environments. The progressive downfan decrease in runoff competence and channel /overbank surface ratios implies enhanced preservation for climatically controlled sedimentary and pedogenicsignatures over the distal domain.