The paleohydrology of Sluice Pond, NE Massachusetts, and its regional significance

Seismic, pollen, stable isotope and lithologic stratigraphies of Sluice Pond, northeastern Massachusetts, were investigated to reconstruct local climate conditions from the latest Pleistocene to present. We present a new lake-level curve, constrained largely by acoustic reflectors and well-dated sediment cores from the deep basin and margin of the lake. Bulk δ34S data from the basin core provide valuable information regarding anoxia and water-column stratification. The lake-level history is corroborated with pollen-based, transfer-function-derived reconstructions of temperature and precipitation from the basin core. The lower stratigraphy reveals a time of cold/dry climate from ca. 11.7–8.2 ka BP (1 ka = 1,000 cal yr), with a minor lake-level increase centered at ca. 11.0 ka BP. An increase in regional temperature/moisture is apparent in sediments younger than 8.2 ka BP. A warm/dry climate is reconstructed from ca. 5.1–3.5 ka BP, concomitant with the well-established regional Tsuga (eastern hemlock) minimum. Sediments deposited since 3.5 ka BP reveal a general deepening of the pond and organic-rich conditions, with another minor dry episode from ca. 2.0–1.3 ka BP. Uppermost sediments record anthropogenic disturbance. The hydroclimate variability inferred from the Sluice Pond sediment record is consistent with previous reconstructions of lake level and vegetation in the southern portion of the northeastern US. It is not, however, consistent with reconstructions from locations farther north, many of which possess evidence of a dry period ca. 9.0–5.0 ka BP. The likely explanation for this discrepancy lies in air mass distribution associated with the position and amplitude of the circumpolar vortex throughout the Holocene. This new record of Holocene regional hydroclimate variability adds to the spatial coverage of existing reconstructions, and helps constrain forcings associated with such variability.