The time sequence of paleoclimatic changes from 245.2 to 147.9 ka B.P. has been established by high precision U-series dating by Thermal ionization Mass Spectrometry and the analysis of the oxygen isotopes from a stalagmite of Shuinan Cave in Guilin. The oxygen isotope pattern is divided into three main intervals. The top part of the stalagmite (interval C) displays mainly relatively heavy oxygen isotopes, mostly -7 to -5‰VPDB, but at a depth of 86.5 cm below the top, there is a sharp change to values lighter than -8 ‰. This boundary, dated at 192.6 ± 3.9 ka B.P. is correlated with the boundary between marine oxygen isotope stages 6 and 7. The underlying interval B has δ18O values consistently between -7.5 and -8.5‰ until 271 cm depth when there is a sharp rise in δ18O values towards values as heavy as -5‰. The upper position of this change is dated at 242.5 ± 6.4 ka B.P. and is correlated with the boundary between marine isotope stages 7 and 8. Carbon isotope values lie between -8.5 and -11‰ and are not uniquely high or low in the three intervals, but also show rapid changes at the boundaries between intervals in the same sense as the shifts in δ18O. The pronounced shifts in δ18O are attributed to changes in the paleo-monsoon intensity which reflect major reorganizations of the climate system, but some regional characteristics are also present. The results are also consistent with previous studies of climate proxies from loess-palaesol sequences in northern China. These characteristics show that paleo-climate evolution since the late stage of the middle Pleistocene Epoch in the Guilin area not only follows the global characteristics, but also has the strong district or regional patterns.
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Acknowledgements This work was supported by a project of Science and Technology Ministry (Grant No. 2003 DEB6J069), that is‘‘The construction of keeping storeroom of the stalagmite samples in cave, China’’, and a key project of National Science Foundation of China (Grant No. 40152002). The authors thank Prof. Ian J. Fairchild (School of Geography, Earth and Environmental Sciences,University of Birmingham, UK) for improving English and the manuscript. About the author Zhang Meiliang, born in 1956, graduated from the Department of Geology of Beijing University in 1980. He is a professor in Institute of Karst Geology (Chinese Academy of Geological Sciences, Guilin, China), and has dealt with research of the regional karst, palaeokarst and global change.
- Guilin, China
- Isotope records
- Palaeo-climate reconstruction
- Shuinan Cave
- TIMS-U series ages