Abstract
Abstract. Over the past decades, paleoenvironmental studies in the Indian summer monsoon region have mainly focused on precipitation change, with few published terrestrial temperature records from the region. We analysed the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) in the sediments of Lake Chenghai in southwest China across the Pleistocene–Holocene transition, to extract both regional hydrological and temperature signals for this important transition period. The lake level was reconstructed from the relative abundance of crenarchaeol in isoGDGTs (%cren) and the crenarchaeol′/crenarchaeol ratio. The %cren-inferred lake level identified a single lowstand (15.4–14.4 ka cal BP), while the crenarchaeol′/crenarchaeol ratio suggests a relatively lower lake level between 15.4–14.4 and 12.5–11.7 ka cal BP, corresponding to periods of weakened ISM during the Heinrich 1 and Younger Dryas cold event. A filtered TetraEther indeX consisting of 86 carbon atoms (TEX86 index) revealed that lake surface temperature was similar to present-day values during the last deglacial period and suggests a substantial warming of ∼4 ∘C from the early Holocene to the mid-Holocene. Our paleotemperature record is generally consistent with other records in southwest China, suggesting that the distribution of isoGDGTs in Lake Chenghai sediments has potential for quantitative paleotemperature reconstruction.
Highlights
Precipitation variation in the Indian summer monsoon (ISM) region has a strong influence over ecosystem function, water availability and economic security across the region (Sinha et al, 2011, 2015; Ljungqvist et al, 2016)
The %Glycerol dialkyl glycerol tetraethers (GDGTs)-0 values had a mean of 74.0 % between 15.4 and 14.4 ka cal BP and a mean of 19.6 % during the 14.4–7.0 ka cal BP interval (Fig. 3)
The lake-level history inferred from %cren shows a relative lowstand of Lake Chenghai during 15.4–14.4 ka cal BP, corresponding to a period of weakened ISM during the Heinrich 1 (H1) cold event
Summary
Precipitation variation in the Indian summer monsoon (ISM) region has a strong influence over ecosystem function, water availability and economic security across the region (Sinha et al, 2011, 2015; Ljungqvist et al, 2016). Scientific interest has been stimulated in understanding the underlying forcing mechanisms behind climate variability in the ISM region on a range of timescales, in order to better predict future monsoonal variations. Wang et al, 2014; Dutt et al, 2015; Wu et al, 2015; Kathayat et al, 2016; Zhang et al, 2017a, b, 2018, 2019; Li et al, 2018; Sun et al, 2019). These studies provide evidence of changes in ISM precipitation on orbital and millennial timescales, with a weakened ISM occurring dur-. Sun et al.: Archaeal lipid-inferred paleohydrology and paleotemperature of Lake Chenghai ing cold events and strengthened ISM occurring during warm intervals
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