Late Holocene Paleoclimate and Environmental Reconstructions of Northeast China by High Resolution Stalagmite Records

<p>Late Holocene Paleoclimate and Environmental Reconstructions of Northeast China by High Resolution Stalagmite RecordsJui-Lin Wang1, Hong-Chun Li1,2*, Horng-Sheng Mii31 Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan, ROC2 School of Geographical Sciences, Northeast Normal University, Changchun, Jilin 130024, China3 Department of Earth Sciences, National Taiwan Normal University, Taipei 11677, Taiwan, ROC Two stalagmites, DSH-1 (7-cm long) and DSH-2 (10-cm long), were collected from Diaoshuihu Cave (43o20’32”N, 125o50’35”, 610 m a.s.l.) in southeast Changchun, Jilin, China in summer 2017. They grew on mud debris of an ancient groundwater flow channel inside the cave and contained significant detritus with yellowish color. 210Pb dating and 14C dating were used to determine the chronology of the stalagmites. The former indicates that both of them have modern deposition and the latter establishes the chronology of the stalagmites which cover 4600-year EAMS climatic record. The two stalagmites show a brief growth hiatus at 0.84-cm depth in DSH-1 and 1-cm depth in DSH-2. Above this hiatus, the stalagmites have lighter color and less detritus. The stalagmites were subsampled at 0.1~0.2 mm intervals for d18O and d13C analyses. A total of 486 measurements for DSH-1 and 698 measurements for DSH-2 of d18O and d13C analyses were made over the past 4800 years. The records of the two stalagmites exhibit similar stable isotopic patterns, demonstrating that they are good paleoclimate records. Based on the chronology determined by 210Pb dating and 14C dating, the stable isotope records compare with the local annual precipitation (1905~2012), warm season rainfall, air temperature, and TSI (Total Solar Irradiance). The comparison between stable isotope records and precipitation shows lighter d18O and d13C corresponding to higher rainfall. Good comparison between the d18O and TSI shows heavier d18O is corresponding to lower TSI, and vice versa. The d13C records co-varies with d18O before 1910 C.E., reflecting that surface vegetation (shown by the d13C) above the cave was mainly influenced by wetness (reflected by the d18O). It is interesting to see that both d18O and d13C values were lower, reflecting wetter climates during the Little Ice Age. A very dry and poor vegetation episode appeared between 1300 and 1400 yr BP. The study area is near the north boundary of East Asian Summer Monsoon and shows quite different precipitation patterns on decadal scales from central and south China, which should be very interesting for climatic study. Key words: Stalagmite, Stable isotope record, Late Holocene </p>