24-15 Late Pleistocene-Holocene Environmental Change from May Pond Sediment Cores and Upland 10Be Ages

Session: Lake Sedimentary Records of Past Climate and Environment (Posters)

Poster Booth No.: 43

Presenting Author:

Justin Stroup

Authors:

Drindak, Adrianna¹, Stroup, Justin S.², Clark, Hannah³, Axford, Yarrow⁴, Burdick, Aidan W.⁵, Kitchel, Nathaniel R.⁶, Oswald, Wyatt⁷, Randall, Anne⁸, Kelly, Meredith A.⁹

(1) Department of Earth Sciences, Dartmouth College, Hanover, , (2) Department of Earth Sciences, Dartmouth College, Hanover, , (3) Department of Earth Sciences, Dartmouth College, Hanover, , (4) Department of Earth, Environmental, and Planetary Sciences, Northwestern University, Evanston, , (5) Department of Earth, Environmental, and Planetary Sciences, Northwestern University, Evanston, , (6) Department of Earth Sciences, Dartmouth College, Hanover, , (7) Marlboro Institute for Liberal Arts & Interdisciplinary Studies, Emerson College, Boston, , (8) Department of Earth Sciences, Dartmouth College, Hanover, , (9) Department of Earth Sciences, Dartmouth College, Hanover, ,

Abstract:

The Pleistocene-Holocene transition (~15-11 ka) marks a shift from glacial to interglacial conditions and, in New England, involved the retreat of the Laurentide Ice Sheet (LIS). Relatively speaking, much is known about the timing of LIS retreat from some major river valleys; however, information from upland areas is sparse and discontinuous. The timing of deglaciation in these areas is critical for tracking the LIS’s dynamic response to rapid warming at the end of the last ice age. This project investigates an upland site in northern Vermont where we use lake-sediment cores and ¹⁰Be dating of the landscape to interpret the timing of deglaciation and the subsequent climatic conditions.

We collected and analyzed an ~11 m-long core from May Pond in Barton, VT. The basal core sediments are unstratified sand and gravel that grade into overlying silt and sand rhythmites. The clastic-organic transition occurs at ~5.8 m. We interpret the basal sediments to indicate deglaciation and the rhythmites to indicate an ice-contact lake environment which gave way to a period of landscape stabilization. The organic deposition above is consistent with a more stable landscape and an increase in lake productivity. We used 5 radiocarbon ages spread across the core to build an age model. Two of these radiocarbon ages, collected from the rhythmites, date to ~14.1 ka BP and provide a minimum age of ice retreat.  The transition from clastic to organic sediments occurred at ~11.6 ka BP and we interpret this transition to indicate landscape stability and a change in lake productivity. Current work entails pairing the lake-sediment record of deglaciation from May Pond with 10Be ages of boulders and bedrock from just northeast and southeast of the pond. A comparison of these data will allow for the interrogation of potential offsets between the minimum limiting lake-bottom radiocarbon ages and ¹⁰Be ages of local deglaciation. This study is one of the first in New England to combine sediment core and ¹⁰Be dating to reconstruct ice-sheet retreat and climate conditions during the Pleistocene and Holocene transition.

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