HR: 15:15h
AN: PP33D-06    [Abstracts]
TI: Holocene Lake Productivity and Inferred Climate Histories From High-Altitude Sites Within the Baroon Taiga Mountains, Northern Mongolia
AU: * Robinson, K D
EM: kdrst16@pitt.edu
AF: University of Pittsburgh, Department of Geology and Planetary Science, 4107 O'Hara Street, Pittsburgh, PA 15260, United States
AU: Rosenmeier, M F
EM: mrosenme@pitt.edu
AF: University of Pittsburgh, Department of Geology and Planetary Science, 4107 O'Hara Street, Pittsburgh, PA 15260, United States
AU: Ortiz, J D
EM: jortiz@kent.edu
AF: Kent State University, Department of Geology, McGilvrey Hall, Lincoln and Summit Streets, Kent, OH 44242, United States
AB: Diffuse reflectance spectroscopy, biogenic silica, and standard loss-on-ignition (LOI) analyses of radiocarbon- dated sediment core samples from Sanjin, Asgat, Ganbold, and Mustei Nuur provide a nearly 11,000 year history of aquatic productivity changes within lakes of the Baroon Taiga Mountains, northern Mongolia. Productivity within these lakes is most sensitive to temperature fluctuations because the catchments are small, nutrient poor, and located at relatively high elevations (greater than 2200 m) with very low annual average temperatures. Within the Mustei Nuur basin, long-term decreases in reflectance and LOI-inferred algal productivity follow orbitally-forced reductions in northern hemisphere solar insolation (i.e., energy receipt) after 8000 years before present (B.P.). Prior to 8000 years ago, enhanced algal productivity within the lake likely reflects increasing northern hemisphere temperature trends following late glacial conditions. Higher frequency (decadal to centennial-scale) changes in biogenic silica, organic matter, and reflectance-inferred algal pigment concentrations within the late Holocene sediment sequences of Sanjin, Asgat, and Ganbold Nuur are interpreted as representing aquatic productivity variations influenced by the length of the ice-free growing season and, by further inference, local temperature variations. Reduced productivity and inferred lower temperatures are documented between 300 and 100 years B.P., roughly coincident with the Little Ice Age, whereas warmer conditions existed from 900-1100 years B.P., and between (roughly) 100 years B.P. and the present. Inferred warming over the last century parallels instrumental data trends, numerous high-latitude (arctic) paleoenvironmental records, and several other notable northern hemisphere temperature reconstructions. Correlations between late Holocene reflectance, biogenic silica, and LOI-inferred aquatic productivity records from the Baroon Taiga alpine lakes and nearby temperature-sensitive tree-ring data sets further supports the inference that the sediment records are representative of regional temperature variations.
UR: http://www.pitt.edu/~mrosenme/central_asia.htm
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1650 Solar variability (7537)
DE: 4914 Continental climate records
DE: 9320 Asia
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting