41 Interpreting Sedimentary Records of Past Changes in Climate and Ecology (Posters)

Monday, 24 March 2014
8:00 AM - 12:00 PM
Freedom Hall A

LATEST PLEISTOCENE AND HOLOCENE SEDIMENT RECORDS FROM WETLANDS IN WESTERN NEW YORK

Paper number: 41-13
Program: Theme Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

We analyzed the post-glacial sediment record of a wetland and adjacent kettle pond at the Beaver Meadow – Buffalo Audubon Society site near the town of Java in western New York. Our goal was to determine climate and environmental fluctuations throughout the late Pleistocene and Holocene. The Beaver Meadow (BM) site is 0.2157 km2 and contains ~3.5 m of post-glacial sediment fill. In contrast, the Dragonfly Kettle bog site (DFK) is smaller (0.0037 km2), has up to 8 m of post-glacial sediment fill, and has fewer disturbances. Sediments at each site were probed with a Russian peat corer and subsequent cores were obtained with a Livingstone coring system in multiple one-meter-long drives. A core from Beaver Meadow (13BM-D) has a total of 3.1 m of sediment; a core from the kettle (13DFK-A) contains 5.96 m of sediment. We completed basic sediment analyses (moisture content, organic content, carbonate content and magnetic susceptibility) at 5 cm resolution on each of the cores. Core 13BM-D contains 1.13 m of silty clay overlain by 0.88 m of marl overlain by 1.8 m of peat. The DFK core stratigraphy includes 0.21 m of fine sand overlain by 2.13 m of gyttja overlain by 3.63 m of peat.

The stratigraphies represent basal glacial sediments followed by lacustrine units (gyttja in kettle, marl in wetland), succeeded by peat. The timeline of post-glacial changes in sedimentation is constrained by radiocarbon dating, which is used to construct age-depth models for each core. An age model based on four radiocarbon ages in the BM core indicates that the transitions from glacial sediments to lacustrine sediments to bog sediments occurred at ~20.9 ka and ~11.1 ka, respectively. An age model based on six radiocarbon ages from 13DFK-A indicates that the transitions from glacial sediments to lacustrine sediments to bog sediments occurred at ~15.5 ka and ~10.8 ka, respectively.

We have a new constraint on deglaciation of this part of New York. We trust DFK’s basal age of 15.5 ka more than the 20.9 ka age from the BM site because the latter was aquatic material in the marl unit that may be influenced by a hard water effect. Both sites have a transition from lacustrine to peat that occurred around the same time (~ 11 ka); therefore, this transition may have a climatic origin, such as increased aridity. Depositional environments may be further constrained with future analyses.