Late Paleozoic Climatic Reconstruction of Western Argentina: Glacial Extent and Deglaciation of Southwestern Gondwana

• Main Author: Pauls, Kathryn N
• Format: Text
• Language: unknown
• Published: UWM Digital Commons 2020
• Subjects: Argentina; Gondwana; late Paleozoic ice age; Paganzo Basin; Paleoclimate; Provenance; Climate; Geochemistry; Geology; South Pole; Chaco; Uspallata; South pole
• Online Access: https://dc.uwm.edu/etd/2576; https://dc.uwm.edu/context/etd/article/3581/viewcontent/Pauls_uwm_0263D_12847.pdf

Throughout its history Earth has experienced both icehouse and greenhouse conditions. Shifts and transitions from one end member to the other are driven by numerous driving mechanisms on global, orbital and more local scales. In particular, the late Paleozoic ice age (LPIA) is thought to have been driven by global drivers such as the drift of the Gondwanan continent across the South Pole, fluctuations in atmospheric CO2 concentrations, and Milankovitch cycles. It was also affected by more local and regional drivers such as active tectonism along accretionary margins and changes in atmospheric and oceanic circulation patterns. South American Gondwana provides an excellent opportunity to examine and evaluate the effects that global versus local driving mechanisms had on regional climates during the shift from icehouse to greenhouse conditions around the Carboniferous-Permian boundary. Of particular interest to this study are the margin and foreland basins of western Argentina in comparison to their paleolatitudinal counterparts of Brazil and eastern Argentina (i.e. the Chaco-Paraná and Paraná basins). This study focuses on determining the extent of glaciation during the Serpukhovian-Bashkirian of the Paganzo and Calingasta-Uspallata basins, the subsequent and relatively early deglaciation and shift in climate from humid conditions to extreme aridity, and the driving mechanisms for this change. This study tracks changes in facies, sediment dispersal, and climate indicators throughout the late Paleozoic strata in the Paganzo, Calingasta-Uspallata and Paraná basins, with special focus on the Paganzo Group strata. Here, we conclude that glaciation of the Paganzo and Calingasta-Uspallata basins was restricted to the Precordilleran region and nucleated on a significant uplift known as the Protoprecordillera and adjacent uplands. A paleoclimate reconstruction for the late Carboniferous using the Chemical Index of Alteration (CIA) indicates a shift from cold and arid to warm and humid following the deglaciation of the ...