70 Limnogeology (Posters)

Tuesday, 22 March 2011
1:30 PM - 5:30 PM
Grand Ballroom

REGIONAL CORRELATION OF SEDIMENT CORES FROM TEA POND, EUSTIS, ME AND CONROY LAKE, MONTICELLO, ME THROUGH A MULTI-PROXY ANALYSIS OF HOLOCENE SEDIMENTS

Paper number: 70-3
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Tea Pond, Eustis, ME and Conroy Lake, Monticello, ME each contain complete Holocene sedimentary records. The purpose of this study is to correlate paleoenvironmental indicators from both lakes, located approximately 237km apart, through a multiple proxy analysis. The total length of sediment sections recovered at Conroy Lake was 743cm and at Tea Pond was 683cm. Age models created from radiocarbon dates taken from these sections have shown the basal age of the Tea Pond core to be ~12,547 14C years BP and Conroy Lake core to have a basal age of ~10,566 14C years BP. Sedimentation rates calculated from the age models show Tea Pond to have a higher average sedimentation rate. Proxies used in this study include, percent organic carbon, percent CaCO3, dry and wet bulk densities, percent H2O, magnetic susceptibility, δ13C, δ15N, atomic C/N ratios and percent nitrogen. Analyzing proxies within constrained ages has allowed for a regional correlation of proxy data.

This study focuses on the analysis of organic matter (OM) preserved in the sedimentary record and has revealed periods of time at which there are correlations in proxy data between lakes and times at which there are not. Analyses into the source of OM through δ13C and atomic C/N ratios have shown lacustrine algae and C3 vascular plants to be the primary OM sources at both Conroy Lake and Tea Pond. Average OM percentages at Tea Pond are 38.7% and at Conroy Lake are 37.8%. Average CaCO3 percentages at Tea Pond are 13.7% and at Conroy Lake are 17.8%. The higher percent of CaCO3 at Conroy Lake can be explained by the limestone bedrock of the Carys Mills Formation. Analyses have led to the interpretation that correlations represent periods of time during which the paleoenvironmental conditions at each lake were influenced by regional climates. Correlations between OM percentages are observed from 0 - 1,500 14C years BP and at 3,700 - 5,000 14C years BP. Conversely, when correlations are not seen in this data between 1,500 - 3,700 14C years BP, the paleoenvironmental conditions may have been influenced more strongly by local environmental conditions. This study has shown correlations in paleoenvironmental proxies from Tea Pond and Conroy Lake throughout the Holocene, which provide useful data in the reconstruction of Holocene climate.