TRACKING FLUVIAL-EOLIAN TRANSPORT IN THE HOLOCENE ANDEAN FORELAND OF ARGENTINA

Continental drainage systems archive records of rock uplift and source area relief (driven by tectonics), precipitation and glaciation (driven by climate), natural resources, and climate/carbon cycles. There has been significant progress in linking such environmental signals to the geomorphic expression of landscapes, as well as in the stratigraphic record of depositional basins in coastal and offshore areas. However, there are large uncertainties regarding the degree to which terrestrial transfer zone processes can modify signals en route from the erosion zone to a sedimentary basin. We investigate a Holocene sediment transfer zone with two competing sediment transport mechanisms: wind and water, to understand how distal eolian systems impact preservation of environmental signals in continental-scale drainage systems. To quantify eolian transport influence in continental drainage systems we employ multiple sediment fingerprinting methods for sand-sized sediment (detrital zircon U-Pb, sandstone petrology), incorporate sediment mixing models, and correlate the findings to the sedimentary record. Three unique fluvial sediment sources from the metamorphic basement outcropping in the Sierras Pampeanas, sedimentary metasedimentary rocks from the Precordillera, and volcanic units from the Frontal Cordillera deliver sediment to the Andean foreland. Though all samples faithful record inputs from the three source regions, a mixing trend is consistent with the north directed paleowind vector where southern Frontal Cordillera river sediment are transported and gradually mixed with Precordillera and Sierras Pampeanas river sediment. The data shows promise to record climatic conditions in Holocene to historical eolian systems that drives sediment storage of Andean river sediment, which starves down-system accumulation zones. Arid regions are particularly sensitive to modern environmental change, where eolian systems are an important component of dryland ecological and hydrological systems. A thorough understanding of processes operating in eolian systems will be important to predicting how these regions will continue to evolve as anthropogenic warming and increased agricultural development continues to shape the Earth’s landscape, resource management, and human land use.