A high-resolution hydrogen isotope record of behenic acid for the past 16 kyr in the northeastern United States

摘要

D/H ratios of leaf lipids from lacustrine aquatic macrophytes have been shown to record precipitation dD values, which can reflect precipitation-weighted mean annual temperature (MAT) in the northeastern United States. Here we report a high-resolution hydrogen isotopic record from Little Pond, Massachusetts, USA, which we compare with other paleoclimate data from the region, including a similar dD record from Blood Pond, Massachusetts. Together the two datasets provide a > 16 ka record of dD variability in the region, affording new insights into Holocene climate history. First, the long-term trends in dD correlate significantly with regional temperatures inferred from alkenone records from nearby areas of the North Atlantic and lake-level inferred changes in precipitation and evaporation. The long-term dD trends reflect a period of maximum regional warmth at ca. 8-6 ka after the collapse of the Laurentide Ice Sheet. Second, unlike the positive relationship between temperature and dD observed over the long-term and during early events like the Younger Dryas, we find that a series of warm and dry events at 4.9-4.6, 4.2-3.9, 2.9-2.1, and 1.3-1.2 cal kya BP coincide with negative dD excursions from the long trends. These events were likely driven by summer drought dynamics. (C) 2017 Elsevier Ltd and INQUA. All rights reserved.