Climatic Instability Study of Lanzhou since Last Glacial Maximum

Organic carbon isotopes, CaCO3 content, coupled with carbonate carbon and oxygen isotopes are presented for identifying the climatic instability of Lanzhou from the Last Glacial Maximum (LGM). A wavelet analysis of these indices was conducted in the Hongzuisi Section, Lanzhou area. The results indicate that some important variations dominated by global factors occurred in 11.5, 13.9, and 15.1 kaB.P. Respectively. In addition, several abrupt oscillations on different time scales during the Holocene can be revealed, indicating the complexity of the climatic system. Although the mechanism of these events has not been interpreted successfully, wavelet analysis can offer a valuable mathematic tool for a detailed analysis and greater understanding of climatic instability, thus providing a useful basis for the research of abrupt events.