Earth and Planetary Sciences ETDs

Publication Date

Summer 7-15-2019

Abstract

Sediment cores from Lake Chalco, central Mexico, were analyzed to reconstruct paleoclimate in the neotropics. This study employs total organic carbon, organic carbon-organic nitrogen ratios, carbon and nitrogen stable isotope ratios of organic matter (OM), and lithology to reconstruct changes in lake level and productivity. During Marine Isotope Stage 3 (~42-29 ka) bulk OM d13C and d15N results suggest the lake experienced strong evaporation and high pH due to warm temperatures and moderate precipitation. Large amounts of terrestrial C3 plant matter were deposited during the Last Glacial Maximum (~22-19 ka), suggesting a swampy environment resulting from reduced precipitation and cooler temperatures because the Intertropical Convergence Zone was located south of, and the mid-latitude storm track north of, Lake Chalco. The deeper part of the core records repeated changes between a lower, evaporative lake and a deeper, productive lake; sections rich in terrestrial C3 plant-rich remains may represent previous glacial maxima.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Peter Fawcett

Second Committee Member

Maya Elrick

Third Committee Member

Zachary Sharp

Language

English

Keywords

paleoclimate, Quaternary, organic geochemistry, Mexico, neotropics, lacustrine

Document Type

Thesis

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