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Environmental variability on the Bolivian Altiplano during the Middle and Late Holocene inferred from paleoenvironmental records from the southern basin of Lake Titicaca and Andean ice cores
The Altiplano, especially Lake Titicaca, was an important center for Pre-Columbian Andean civilizations, with an archaeological record dating back to ~3500 cal yr BP. There have been many studies on the Lake to reconstruct past climate and environment, but uncertainty exists about the timing and duration of Holocene lake-level changes. This dissertation examines paleoenvironmental records from Lake Titicaca and Andean glaciers in an effort to clarify environmental conditions during the Holocene. Geological and archaeological processes operate at different temporal and spatial scales, and their inherent properties affect and limit interpretation of the data. Thus, integrating data from different fields can be challenging. Two studies from the Titicaca Basin are discussed in light of the differences in scales inherent in the deposits that were analyzed. This project proposes that understanding these scales helps to understand what questions can and cannot be addressed with a specific record. Prior studies have shown a desiccation of Lake Titicaca’s southern basin, Lago Huiñaimarca, prior to ~3500 cal yr BP, followed by fluctuating lake level. The timing and duration of dry periods are unclear, because current records are based on event stratigraphy of extreme lake-level declines rather than a continuous record of lake-level change. Archaeologists need sub-century resolution of the lake-level record to understand how human culture adapted to the changes that may have affected aquatic resource use. This study presents high-resolution diatom data from Lago Huiñaimarca (~6500 cal yr BP). It demonstrates that lowstands were probably of shorter duration than previously thought and that lake level fluctuated on the sub-century scale. Ice cores from tropical glaciers offer high-resolution records of past climate events in South America, often providing annual resolution. This chapter examines diatoms observed in ice cores from three glaciers in the tropical Andes (Quelccaya, Coropuna, and Sajama) and documents the species, many of which are cosmopolitan and aerophilic. These diatoms may have originated from local wetlands or seasonal melt water ponds. However, long-distance transport is also a possibility. Furthermore, due to the cosmopolitan nature of the species present and low abundance, these records are limited in their utility for paleoenvironmental reconstruction.
Weide, Denise Marie, "Environmental variability on the Bolivian Altiplano during the Middle and Late Holocene inferred from paleoenvironmental records from the southern basin of Lake Titicaca and Andean ice cores" (2016). ETD collection for University of Nebraska - Lincoln. AAI10141691.