辽宁朝阳凤凰山古土壤序列粒度特征与古气候变化

Grain-Size Characteristics and Climatic Changes of a Paleosol Sequence atF enghuang Mountain in Chaoyang,Liaoning Province

通过对朝阳凤凰山剖面风成古土壤序列进行2cm间距的高密度连续采样,测量样品的粒度百分含量,分析不同粒度组分的古气候意义,选择了粗粒组分、超细粒组分和细粒组分的百分含量分别作为研究区冬、夏季风和西风强度变化的替代性指标,分析了71～453kaBP间该剖面记载的冬、夏季风和西风的演化和古气候变迁。结果表明:71～453kaBP辽宁地区冬、夏季风和西风变化较同步,其中夏季风和西风的变化趋势较一致,明显存在着4个增强阶段和4个减弱阶段,与深海氧同位素曲线的MIS5～MIS12这8个阶段相对应。冬季风的变化趋势与夏季风和西风的变化趋势相反。该时期辽宁地区的古气候变化可以划分为8个阶段:其中71～148kaBP,176～208kaBP,225～243kaBP和311～403kaBP阶段为温暖湿润气候;148～176kaBP,208～225kaBP,243～311kaBP和403～423kaBP阶段为较寒冷干燥气候。

Based on the grain-size analysis of the paleosol section at Fenghuang Mountain in Chaoyang, Liaoning Province, the percentages of the coarse grains, fine grains and supper-fine grains were used as indicators of winter monsoon, westerly wind and summer monsoon strengths, respectively. The results show that the winter monsoon, westerly wind and summer monsoon change synchronously. The westerly wind and summer monsoon have the same variation trend, and there are 4 enhanced stages and 4 decreased stages plotted. The winter monsoon has the opposite variation trend. The climate was warm and wet at the following stages： 71-148 ka BP, 176-208 ka BP, 225-243 ka BP, and 311-403 ka BP ; and the climate was cold and dry at the following stages： 148-176 ka BP, 208-225 ka BP, 243-311 ka BP and 403-423 ka BP.