Abstract

A sediment core from northwestern Lake Huron contains a sequence of red and gray layered sediments that are postglacial and early Holocene glaciolacustrine varves. Two hundred and sixty four couplets were identified and measured using a newly developed image-analysis technique that produces records of seasonal and total varve thickness. On the premise that changes in varve thickness can serve as a proxy for climate variability, we use this information, along with oxygen-isotope records and seismic reflection profile data, to characterize a period immediately following the Younger Dryas. A time-series analysis of the thickness data was performed using two different techniques to characterize changes in spectral density that occur throughout the time span of the record. The results indicate that there are concentrations in variance that occur in the same frequency band as the quasi-periodic El Niño - Southern oscillation (ENSO) and the quasi-biennial oscillation (QBO). The effects of ENSO-like variability have not previously been documented in the postglacial and early Holocene of the Great Lakes region.

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