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An n-alkane and carbon isotope record during the last deglaciation from annually laminated sediment in Lake Xiaolongwan, northeastern China
- Sun, Qing, Xie, Manman, Lin, Yuan, Shan, Yabing, Zhu, Qingzeng, Xu, Deke, Su, Youliang, Rioual, Patrick, Chu, Guoqiang
- Journal of paleolimnology 2016 v.56 no.2-3 pp. 189-203
- C3 plants, alkanes, biomarkers, carbon, climatic factors, deciduous forests, ice, lakes, latitude, limnology, macrophytes, monsoon season, oxygen, paleontology, sediments, stable isotopes, temperature, time series analysis, China, Greenland
- The last deglaciation is of great interest because Northern Hemisphere climate has gone through several abrupt changes. We present an n-alkane and compound-specific carbon isotope record of the last deglaciation from the annually laminated sedimentary sequence of Lake Xiaolongwan, northeastern China. The n-alkane distribution suggests that the sparsely distributed vegetation prior to 14.7 ka BP, changed to wood plants and aquatic macrophytes in the early Bølling-Allerød, and was followed by a broadleaved deciduous forest after 11.4 ka BP. In this forest region, where the vegetation is dominated by C3 plants, the compound-specific δ¹³C value of the long-chain n-alkanes (nC₂₇, nC₂₉ and nC₃₁) is interpreted as a proxy of effective precipitation, while temperature might play a minor secondary role. The positive δ¹³C₂₇–₃₁ values during the Bølling-Allerød suggest a dry-warm climatic condition, while the negative δ¹³C₂₇–₃₁ at 13.0–11.4 ka BP indicates a cold-wet climate during the Younger Dryas in this region. Two periods with lower δ¹³C₂₇–₃₁ occurred at 16.1–16.5 and 17.3–17.7 ka BP and could be associated with the Heinrich event-1a and the Heinrich event-1b, respectively. The synchroneity between the biomarker time series in Lake Xiaolongwan and the δ¹⁸O record from the Greenland ice core suggest the dominance of high latitude processes on regional monsoon evolution from the last glacial, the Bølling-Allerød, the Younger Dryas to early Holocene. Regionally, the Okhotsk High might have played an important role for abrupt changes during the glacial/interglacial transition.