| Abstract | The Parana Delta is one of the most studied deltas in South America, holding one of the most complete records of the Late Holocene in southern South America. The delta encompasses an area of ~17,400 km2 enclosed in the Rio de la Plata estuary, growing steadily at a rate of approximately 2 km2 yr-1 for roughly the past 6000 yrs. This deltaic system has shifted from fluvial, to wave-dominated, and then back to its present day fluvial dominated system creating striking geomorphologic features across the delta. Aerial and satellite imagery, shallow boreholes, radiometric dating of shells and sand, and Ground Penetrating Radar are used to define the distinctive sedimentary features of the delta. Although these studies appear to encompass the entirety of the delta, the uppermost part of the delta remains poorly studied. Sedimentary cores collected from the lower reaches of the upper delta date the early stages delta growth. The one available OSL (Optically Stimulated Luminescence) date from the early set of beach ridges show the delta to be ~8100 yrs old. Previous dates collected from younger beach ridge sets estimated the delta was approximately 6000 yrs old. If the delta proves to in-fact be at least 8100 yrs old, this would make it one of the oldest if not the oldest modern deltas in the world. The purpose of this study is to establish a depositional and chronologic model for the upper, middle, and lower parts of the delta through the collection of sediment cores for facies analysis and radiometric dating. This model will determine early delta processes and test preliminary estimates of delta initiation at ~8500 yrs. B.P. Using the facies analysis and the radiometric dates, accurate depositional and chronological models will be generated to better understand the initiation and development of the Parana Delta. |
