Lignin Oxidation Products in Sediments of Lake Baikal: Indicators of Late Quaternary Paleovegetation and Paleoclimate Change in North-Central Asia

The use of organic molecular marker compounds such as lignin oxidation products (LOP) in studies of ancient sediments is a new approach that may provide useful information on changes in paleovegetation triggered by changes in climate. LOP’s are a series of methoxy phenols derived exclusively from the lignin of vascular plants. As a paleoenvironmental tool, LOP provides information on changes over time in the relative amounts of terrigenous organic matter transported to sediments, and on changes in the taxonomic characteristics of terrestrial vegetation in response to climate. We have used this LOP approach in studies of sediments from three cores collected in Lake Baikal during 1990, as part of a joint USA/Russian study of the paleoclimate of this region. These cores are from three different locations in the lake, with core bottoms ranging in age from about 8,000–38,0000 yr BP, based on radiocarbon dating. In all cores, the concentrations of organic C, total N, and LOP are low, with ranges of 0.2–2.8%, 0.02–0.3%, and 0.05–1.8 mg/10 g sediment, respectively. All three cores exhibit a large subsurface maximum in organic C at about 6,500 yr BP, which may be useful for stratigraphic correlation. Interpretation of the LOP results indicate seven paleovegetation zones from 14,000 yr BP to the present. These zones range from the grass and sedge dominated vegetation at the end of the last glacial maximum (at 14,000 yr BP) to mixed gymnosperm/angiosperm forests representing warmer and more humid periods during the Holocene.