47 Records of Environmental Change from Lacustrine Archives (Posters)

Tuesday, 22 March 2016
1:30 PM - 5:30 PM
Convention Hall

A ~13,000 YEAR RECORD OF CLIMATE AND ENVIRONMENTAL CHANGE AT ZURICH BOG, NY

Paper number: 47-3
Program: Theme Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Long, continuous sediment core records are critical for assessing the evolution of climate and ecosystems during the Holocene. A ~7.3 m long vibracore was collected from Zurich Bog in order to learn about past climate and environmental conditions in the New York Finger Lakes region over the last ~13,000 years. We analyzed the core using several climate proxies: loss-on-ignition (weight percent organic matter, carbonate, and terrigenous sediment), bulk magnetic susceptibility, atomic C/N ratios, and the stable carbon isotopic composition (δ13C) of bulk organic matter. Five radiocarbon ages, from three stratigraphic levels in the core, were calibrated to calendar years using CALIB 7.1 and then a constant linear sedimentation rate was assumed between these dated intervals to create an age-depth model.

We recognized three main units in the core. The base of the core (Unit 1) is ~0.4 m thick and comprised of alternating light gray silty clay and sand beds with very minor, if any, organic matter. The middle unit (Unit 2), ~3.2 m thick, is made up of banded to laminated brown to beige silt. Autochthonous organic matter and calcite are the primary components of this unit. The uppermost unit (Unit 3), ~3.7 m thick is made of peat. This unit exhibits a gradual increase in terrestrial organic matter from ~70 to ~95% upcore. Each transition between units demarcates an important shift in the landscape. Between Unit 1 and 2, the region abruptly transitioned from a relatively shallow bay of proglacial Lake Iroquois to a smaller isolated lake at ~13,000 years ago. This small, relatively shallow lake probably existed for ~7,000 years. The lake slowly became more eutrophic as it filled in with mainly terrigenous sediment and terrestrial organic matter. Since then, this site has been a fen to bog-type environment. Future work includes spectral analysis of the climate proxy datasets to identify significant periodicities using the Singular Spectrum Analysis and Multi Taper Method.

Geological Society of America Abstracts with Programs. Vol. 48, No. 1

doi: 10.1130/abs/2016NE-272679

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