Middle to Late Pleistocene Paleoenvironmental Reconstructions from Lake El'gygytgyn, Arctic Russia

• Main Author: Habicht, Mary Helen
• Format: Text
• Language: unknown
• Published: ScholarWorks@UMass Amherst 2019
• Subjects: Arctic; paleoclimate; biomarkers; branched GDGTs; plant leaf waxes; Pleistocene; Biogeochemistry; Earth Sciences; Geochemistry; Paleobiology; Anadyr; Anadyr'; Chukotka; Climate change; Ice; permafrost; Sea ice
• Online Access: https://scholarworks.umass.edu/dissertations_2/1669; https://doi.org/10.7275/15018735; https://scholarworks.umass.edu/context/dissertations_2/article/2757/viewcontent/Habicht_Dissertation_final_formatting.pdf

Climate change is a major issue challenging the world today. Our global society faces rising temperatures, variable weather patterns, and rising sea level among other associated issues. Our action (or inaction) to address current changes will have serious ramifications for life on our planet in the coming centuries and millennia. In order to provide context for these present and future changes, we can utilize the paleo record to understand the natural variability of Earth’s climate system. One region of the world is changing more rapidly than the global average. Over recent decades, the Arctic has experienced warmer temperatures, reduced sea ice, melting permafrost, and shifts in the amount and seasonality of precipitation. Unfortunately, paleoclimate and environmental records from the terrestrial Arctic, particularly beyond the last 120 ka, are few. This is due to the repeated extensive glaciation of the northern hemisphere high latitudes during the ice ages of the Quaternary. One area of the Arctic, in the Anadyr mountains of Chukotka, has remained unglaciated through the Pleistocene. Lake El’gygytgyn, a meteorite impact crater lake formed 3.6 million years ago lies in this area and so provides a continuous sedimentary sequence from the Mid-Pliocene to present. This dissertation includes four studies of Lake El’gygytgyn sediments over the last 800 thousand years. A variety of biogeochemical and stable isotope proxies are used to reconstruct climate and environmental variability throughout the study interval. These studies provide novel information about the natural variations of terrestrial Arctic climate on glacial-interglacial timescales. Chapter 2 of this dissertation involves the analysis of bacterial membrane lipids called branched glycerol dialkyl glycerol tetraethers (brGDGTs) and plant leaf wax n-alkanes to provide records of relative temperature change and terrestrial vegetation turnover in response to aridity during the glacial-intergacial cycles of the Mid-Pleistocene. Our data suggests that ...