The Continental Record of Marine Isotope Stage 3 (MIS 3; ~60?25 ka) in Central Argentina: Evidence from Fluvial and Aeolian Sequences

MEHL, ADRIANA; ZÁRATE, MARCELO A.; TRIPALDI, ALFONSINA

Marine Isotope Stage 3 in Southern South America 60 ka PB-30 ka PB

Springer

Lugar: Berlin; Año: 2016; p. 167 - 181

Marine Isotope Stage 3 (MIS 3) is characterized by high climatic variabilityresulting from numerous centennial to millennial scale events. The environmentaland climatic reconstruction of this interval is restricted by the sparsity ofhigh-resolution (centennial-scale) terrestrial records in most of South America. Thiscontribution is an attempt to reconstruct the general environmental and climaticconditions of southern South America during MIS 3 by means of continentalrecords located in central Argentina; this is an extensive and heterogeneous regionmade up of diverse geomorphological settings under different climatic conditions.Therefore, the main features of several aeolian and fluvial records situated in differentgeomorphological settings across the region are overviewed. The resultsindicate the predominance of regional aggradation during MIS 3 with differences inthe accumulation rates and dominance of either aeolian or fluvial depositsdepending on the geomorphological setting. The aggradation process was interruptedby stability intervals evidenced by paleosols in the San Rafael plain, the SanLuis paleo-dunefield, the eastern Sierras Pampeanas piedmont and the easternPampean plain. The paleosols might represent lapses of decreasing aeolian inputand perhaps more humid conditions. In addition, paleobiological indicators fromalluvial sequences suggest higher temperatures and water availability between 35and 31 ka in the Andean piedmont, while dry subhumid or strongly seasonalconditions with alternating subhumid-humid phases were inferred in the easternPampean plain during MIS 3. These intervals tend to cluster during the second partof MIS 3, and might reflect the environmental responses to some of the climatic oscillations that occurred during MIS 3. Detailed analysis and a more adjustedchronology are needed to correlate the aeolian and fluvial episodes along with thestability intervals at regional and continental scales.