Sediment focusing in Mirror Lake, New Hampshire1

作者：Margaret Bryan Davis, Mary S. Ford · 发表于：Limnology and Oceanography · 年份：1982 · DOI：10.4319/lo.1982.27.1.0137 · 被引用次数：231 · 研究领域：Geology and Paleoclimatology Research、Pleistocene-Era Hominins and Archaeology、Isotope Analysis in Ecology

Analyses of multiple sediment cores from Mirror Lake, New Hampshire, dated by 14C and pollen, show that between 14,000 and 11,000 b.p. silts and sands were deposited over 85% of the basin. After 11,000 b.p. organic‐rich sediments were focused into the deeper parts of the basin, and no sediment accumulated in water <5 m deep. Late‐glacial particulate inorganic inputs were 33 times greater than modern losses from forested watersheds at Hubbard Brook. After trees became established, inorganic inputs fell sharply to modern levels. Late‐glacial organic inputs were a half the average during the last 11,000 years. At four of the sites studied, accumulation rates reached a maximum between 7000 and 4000 b.p. The precise date varies from site to site, suggesting that it would be misleading to link peak accumulation in a single core to events in the watershed. After 4000 b.p. organic sediment accumulation rates declined at all four sites. Parallel declines in accumulation rates of both pollen and inorganic sediments suggest that this decline is due to the process of sediment focusing rather than to a change in decomposition rates or in organic inputs related to autochthonous or allochthonous primary production.