A multi-proxy lithostratigraphic record of Late Glacial and Holocene climate variability from Piper Lake, Nova Scotia

Abstract

A multi-proxy lithostratigraphic record from Piper Lake, Nova Scotia reveals environmental variability during the Late Glacial and Holocene. Piper Lake is a small, shallow (3 m), closed dystrophic basin located in the eastern Nova Scotia Highlands. The site was deglaciated about 14.5 cal (calibrated) ka BP and elevated loss on ignition values and relatively low carbon/nitrogen (C/N) isotope ratios indicate the establishment of a productive aquatic environment consistent with Allerød warming. The Late Glacial Lake record is punctuated by two thin, very fine-grained clay layers that are correlative to the Killarney and Younger Dryas (YD) oscillations; they were deposited when perennial ice covered the lake. The post-YD lithostratigraphy indicates the rapid establishment of an increasingly productive and stable landscape. This trend is reversed three times during the Holocene by minerogenic units. A complex 25 cm thick diamicton unique to Piper Lake was deposited ca. 10.8–10.3 cal ka BP by slumping that was associated with periglacial slope processes and (or) lake level changes; a direct correlation to early Holocene (Preboreal) cooling appears unlikely. Two thin minerogenic units deposited at ca. 8.1 and ca. 4.9 cal ka BP were likely the result of regional cooling and are broadly correlative with events noted in the GISP2 (Greenland Ice Sheet Project 2) ice-core record. The Holocene lithostratigraphic record from Piper Lake may be a consequence of unique limnological factors. Alternatively, the strong lithostratigraphic response may be the result of the absence of a strong and persistent regional climate mechanism (North Atlantic oscillation?), which if present might have obscured the impact of hemispheric or larger-scale climate forcing.