Date of Award

Spring 2023

Document Type

Open Access Thesis



First Advisor

Andrew Leier


Wind-blown dust from southern South America links the terrestrial, marine, atmospheric, and biologic components of Earth’s climate system. The Pampas of central Argentina (~33-40° S) contain an extensive upper Miocene to Holocene eolian record that spans the relatively warm conditions of the Late Miocene to cooler climates of the Plio-Pleistocene and Holocene. We collected 13 loess, paleosol, and fluvial samples from the upper Miocene Cerro Azul and Rio Negro Formations which resulted in n = 5129 new detrital zircon U-Pb ages. Late Miocene rivers conveyed sediment from northern Patagonia, the Andes adjacent to the Pampas, and the Sierras Pampeanas to the foreland where it was entrained and transported by prevailing winds. Upper Miocene sediment provenance is nearly identical to recent eolian deposits, indicating the Pampas are part of a long-lived fluvial-eolian dust production system in operation since at least the Late Miocene. The onset of the eolian transport in the Pampas coincided with a global phase of cooling temperatures and aridification. The role of Late Miocene rivers in supplying sediment to the foreland underscores the importance of fluvial transport in the development and maintenance of temporally persistent mid-latitude loess provinces during the Neogene


© 2023, Blake Marcus Stubbins

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