TY - JOUR
T1 - Last glacial to post glacial climate changes in continental Asia inferred from multi-proxy records (geochemistry, clay mineralogy, and paleontology) from Lake Hovsgol, northwest Mongolia
AU - Watanabe, Takahiro
AU - Minoura, Koji
AU - Nara, Fumiko Watanabe
AU - Shichi, Koji
AU - Horiuchi, Kazuho
AU - Kakegawa, Takeshi
AU - Kawai, Takayoshi
N1 - Funding Information:
N. Fagel, T.M. Cronin and two anonymous reviewers are acknowledged for their helpful comments and suggestions for improving the manuscript. We thank the captain and crew of the R/V Dybovsky and the Russian/Japanese/Mongolian scientific party researching Lake Hovsgol sediments in 2001 for their cooperation in collecting the sediment core samples. We thank D. Tomurhuu for the preservation and transportation of the sediment cores. T. Sakai, Y. Kobayashi, and T. Kegai were helpful during sample preparation and analyses. We acknowledge the financial assistance from the Japan Baikal Association (JABIRP). This work was partly supported by Sumitomo Foundation grant to K.H. (No. 033425 ) and by a Grant-in-Aid for JSPS Fellows to T.W. (No. 20-4967 ).
PY - 2012/5
Y1 - 2012/5
N2 - Multi-proxy records (geochemistry, clay mineralogy and paleontology) from three sediment cores from Lake Hovsgol, northwest Mongolia, provide paleoenvironmental changes in continental Asia from the last glacial to the present (during the last 29calka BP). This paper presents the first continuous δ13C and δ18O dataset for ostracod shells (Cytherissa lacustris) from Lake Hovsgol sediments. A positive shift in ostracod δ13C values (from +0.5‰ to +3.2‰) began at ca. 21calka BP, and was associated with a decrease in δ13C values of total organic carbon (from -24.7‰ to -27.3‰) and an increase in the mass accumulation rate of total organic carbon (MAR-TOC). These results suggest that increased lake productivity led to the 13C-enrichment of dissolved inorganic carbon in Lake Hovsgol. In addition, decreases in clay content and the illite crystallinity index (full width at half maximum of the 10Å peak) began at ca. 21calka BP, indicating an increase in surface runoff and a change in sources of clastic materials in the watershed. The highest δ18Oostracod values (up to -4.8‰) at 16-15calka BP indicate the increases in precipitation from the East Asian monsoon. The total pollen amount increased, and Betula, Alnus, and Salix were dominant (up to 53%, 30%, and 6%, respectively) after 16-15calka BP. These findings indicate that broad-leaved trees expanded around Lake Hovsgol. In addition, fossil diatom valves appeared after 16-15calka BP, suggesting climate amelioration, and increased input of soil-derived nutrients and dissolved silica. Between 10 and 5calka BP (Holocene climate optimum), productivity was high in and around the lake (MAR-TOC, up to 47.3mg/cm2kyr; MAR-diatoms, up to 14.4×108 valves/cm2kyr; total pollen concentration, up to 9.0×105 grains/cm3). Environmental changes during the last 29kyr in and around Lake Hovsgol are clearly associated with fluctuations in summer insolation and East Asian monsoon intensity.
AB - Multi-proxy records (geochemistry, clay mineralogy and paleontology) from three sediment cores from Lake Hovsgol, northwest Mongolia, provide paleoenvironmental changes in continental Asia from the last glacial to the present (during the last 29calka BP). This paper presents the first continuous δ13C and δ18O dataset for ostracod shells (Cytherissa lacustris) from Lake Hovsgol sediments. A positive shift in ostracod δ13C values (from +0.5‰ to +3.2‰) began at ca. 21calka BP, and was associated with a decrease in δ13C values of total organic carbon (from -24.7‰ to -27.3‰) and an increase in the mass accumulation rate of total organic carbon (MAR-TOC). These results suggest that increased lake productivity led to the 13C-enrichment of dissolved inorganic carbon in Lake Hovsgol. In addition, decreases in clay content and the illite crystallinity index (full width at half maximum of the 10Å peak) began at ca. 21calka BP, indicating an increase in surface runoff and a change in sources of clastic materials in the watershed. The highest δ18Oostracod values (up to -4.8‰) at 16-15calka BP indicate the increases in precipitation from the East Asian monsoon. The total pollen amount increased, and Betula, Alnus, and Salix were dominant (up to 53%, 30%, and 6%, respectively) after 16-15calka BP. These findings indicate that broad-leaved trees expanded around Lake Hovsgol. In addition, fossil diatom valves appeared after 16-15calka BP, suggesting climate amelioration, and increased input of soil-derived nutrients and dissolved silica. Between 10 and 5calka BP (Holocene climate optimum), productivity was high in and around the lake (MAR-TOC, up to 47.3mg/cm2kyr; MAR-diatoms, up to 14.4×108 valves/cm2kyr; total pollen concentration, up to 9.0×105 grains/cm3). Environmental changes during the last 29kyr in and around Lake Hovsgol are clearly associated with fluctuations in summer insolation and East Asian monsoon intensity.
KW - East Asian monsoon
KW - Lake sediment
KW - Mongolia
KW - Stable carbon and oxygen isotope ratios
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U2 - 10.1016/j.gloplacha.2012.03.005
DO - 10.1016/j.gloplacha.2012.03.005
M3 - Article
AN - SCOPUS:84860526512
VL - 88-89
SP - 53
EP - 63
JO - Global and Planetary Change
JF - Global and Planetary Change
SN - 0921-8181
ER -
