RECONSTRUCTING LATE PLIOCENE ENVIRONMENTAL CHANGE AT LAKE EL'GYGYTGYN, ARCTIC NORTHEAST RUSSIA

The Late Pliocene (~3.5-2.5 Million years ago, Ma) is the most recent period in Earth's history when atmospheric CO₂ levels were similar to present, suggesting it may provide a good analogue to future climate scenarios. Many studies have demonstrated that the Arctic was especially warm during the Pliocene, but there is a lack of temporally continuous climate records to characterize the spatial and temporal climatic variability of the Pliocene Arctic and provide a target for climate model hindcasts. Here we present the first measurements of leaf waxes (n-alkanes) and glycerol dialkyl glycerol tetraethers (GDGTs) from the Pliocene section of the Lake El'gygytgyn composite core. Lake El'gygytgyn is located in northeastern Arctic Russia, and contains a continuous climatic record for the last 3.6 Million years remarkably coherent with other records of global change. Our organic geochemical proxy reconstructions will provide insight into vegetation changes (based on n-alkane characteristics) and summer temperatures (the GDGT-based TEX₈₆ and MBT/CBT indicies) at the lake. In addition, we plan to measure the deuterium enrichment of n-alkanes, which linearly track the deuterium enrichment of precipitation and thus reflect how the mechanisms of the hydrological cycle vary through time. We present a subsection of the Pliocene section of the core (2.8 Ma to 2.4 Ma) and initial measurements of these proxies and discuss progress toward providing a sub-centenial reconstruction of hydrological cycling and summer temperatures in the Pliocene Arctic.