HOLOCENE CLIMATE CHANGES RECORDED BY MERCURY CONCENTEATION IN PEAT: A CASE FROM QINONGGOU OF YANGBAJING, TIBETAN PLATEAU

We tried in this endeavor to rebuild the time series of temperature changes in Qinonggou(QNG) of Yangbajing in the southeast of the Tibetan Plateau. It is found that the mercury concentration in peat is a kind of good climatic proxy to monitor the regional temperature changes. The QNG peat recorded the variation in temperature form 9.1 kaBP to 3.5 kaBP in Holocene and could be divided into three phases: The PhaseⅠ(about 9.1 ~7.2 kaBP)was in the Holocene Megathermal stage of high temperature, but started dropping. The PhaseⅡ(about 7.2 ~5.6 kaBP), was the stage with fluctuated temperature changes. There occurred two large cold events happened in 5.9 kaBP and 6.3 kaBP respectively. The Phase Ⅲ(about 5.6 ~3.5 kaBP), was a stage showing a falling pattern with violent and frequent fluctuations. They may be correlated with the three events of ice rafted debris(IRD) in the North Atlantic Ocean, i.e. the 8.2, 5.9 and 4.2 ka events. In addition to them, there were also some cold events in 7.5 kaBP, 6.3 kaBP and 4.7 kaBP respectively. Using REDFIT to make red noise spectrum analysis, we observed from the peat mercury concentration some cycles in aquasi-periods of 1 100, 650, 450, 310 and 110 a, as a response to different scales of solar activities, suggesting that the region is much sensitive to the climatic changes caused by solar activities.