摘要
Modern meteorological observations have proved that climate change in the northeast Tibet plateau is characteristic of alternations of plateau summer and winter monsoons, and climate change in Chinese Loess plateau is geared by variations of East Asian summer and winter monsoon strengths. A transitional zone between regions dominated by plateau monsoon and East Asian monsoon respectively is located at around 110°E in China. The two monsoon systems are driven by different forcing aspects.Here we show the two climatic systems change during the last interglacial period (IG) by examining geological records. Two aeolian loess\|paleosol sequences,one is located in northeast Tibet plateau closed to Xining and the other one in the northwest Loess plateau closed to Huanxian, were investigated. Age frames of the paleosol and intercalated loess are achieved by Thermoluminescence dating, palaeomagnetic measurements and stratigraphy correlation. Samples taken from Huanxian section were at 5cm intervals, and samples from Xining section were taken at every 10cm. The samples were measured for magnetic susceptibility (MS), rubidium/strontium value (Rb/Sr), Calcium carbonate content (CaCO\-3) and grain\|size distribution (GS). Detail time scale is obtained by two steps. First, correlate MS curves with deep\|sea oxygen isotope time series of stage 4,5 and 6 of Martinson et al (1987) to assign ages of boundaries of stratigraphic units. Second, linearly interpolate ages between the obtained ages and therefore get age of each sampling point.
Modern meteorological observations have proved that climate change in the northeast Tibet plateau is characteristic of alternations of plateau summer and winter monsoons, and climate change in Chinese Loess plateau is geared by variations of East Asian summer and winter monsoon strengths. A transitional zone between regions dominated by plateau monsoon and East Asian monsoon respectively is located at around 110°E in China. The two monsoon systems are driven by different forcing aspects.Here we show the two climatic systems change during the last interglacial period (IG) by examining geological records. Two aeolian loess\|paleosol sequences,one is located in northeast Tibet plateau closed to Xining and the other one in the northwest Loess plateau closed to Huanxian, were investigated. Age frames of the paleosol and intercalated loess are achieved by Thermoluminescence dating, palaeomagnetic measurements and stratigraphy correlation. Samples taken from Huanxian section were at 5cm intervals, and samples from Xining section were taken at every 10cm. The samples were measured for magnetic susceptibility (MS), rubidium/strontium value (Rb/Sr), Calcium carbonate content (CaCO\-3) and grain\|size distribution (GS). Detail time scale is obtained by two steps. First, correlate MS curves with deep\|sea oxygen isotope time series of stage 4,5 and 6 of Martinson et al (1987) to assign ages of boundaries of stratigraphic units. Second, linearly interpolate ages between the obtained ages and therefore get age of each sampling point.
出处
《地学前缘》
EI
CAS
CSCD
2000年第S1期389-390,共2页
Earth Science Frontiers
基金
theNationalKeyProjectforBasicResearchonTibetPlateau (G19980 4 80 0 )andtheNationalNaturalSci encesFoundationofChina (No.4 990
