Dissertation/Thesis Abstract

Tying Hydrologic Balance and Human Settlement through Stable Isotope Analysis of Lacustrine Sediments (Titicaca Basin, Peru)
by Vaught-Mijares, Roxanna, M.S., University of Louisiana at Lafayette, 2018, 59; 10813699
Abstract (Summary)

Drought and flood events are thought to have shaped the ways in which Andean societies have adapted to life in the Titicaca Basin region, particularly regarding land use practices and settlement patterns. Therefore, water balance is intricately connected to the livelihood of these societies and our objective is to understand that balance. Here, we measure oxygen (δ18O) and carbon (δ13C) isotopes of authigenic carbonate minerals in two AMS radiocarbon dated sediment cores collected from Lagunas Orurillo and Umayo in the Titicaca Basin of Peru in order to reconstruct paleohydrology across the last 5,000 and 7,000 years, respectively. We hypothesize that if the Holocene is becoming increasingly wet, then we expect the isotope values of both cores to reflect similar trends towards wetter conditions. Results indicate that Orurillo became wetter during the late Holocene, consistent with our hypothesis and existing hydrologic records from Titicaca, Junin, and Pumacocha, whereas data from Umayo confirm an earlier study (Baker et al., 2009) that suggested increasingly dry conditions throughout the Holocene. Regional wetting has been partially attributed to large-scale phenomena such as El Niño Southern Oscillation (ENSO) and variations in the South American Summer Monsoon (SASM). This observed departure at Umayo might be associated with a more regional glacial groundwater source as opposed to any overarching climate factors, such as El Niño Southern Oscillation (ENSO) or the increasing strength of the South American Summer Monsoon (SASM). Results from Umayo suggest that interpretations of δ13C and δ18O from lake sediments must consider local hydrologic conditions before interpreting regional climate trends, such as ENSO and SASM.

Indexing (document details)
Advisor: Hillman, Aubrey L.
Commitee: Gottardi, Raphael, Schubert, Brian
School: University of Louisiana at Lafayette
Department: Geology
School Location: United States -- Louisiana
Source: MAI 58/05M(E), Masters Abstracts International
Source Type: DISSERTATION
Subjects: Geology, Paleoclimate Science, Limnology
Keywords: Andes, Paleolimnology, Peru, South American Summer Monsoon (SASM), Stable isotopes, Titicaca Basin
Publication Number: 10813699
ISBN: 978-1-392-04128-4
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