摘要
末次冰期间冰阶(40～22kaBP),黄旗海最高古湖面稳定在1310～1318m之间,比现代湖面约高50m,湖泊面积达到450～515km2(平均为466km2),是现代湖面101km2(1950～1961年平均值)的4.4～5.1倍,湖泊补给系数7.8～9.1。利用逐次逼近法寻找古流域的现代气候相似区域,从而确定相关参数定量重建古降水量;在此基础上,附加另外两个过程,检验了重建结果的可靠性。重建结果认为:40～22kaBP古湖面稳定存在时,黄旗海流域的古降水量可达479～497mm/a,比现在年平均值(353mm/a)高约126～144mm/a。
In monsoon area of eastern Asia, the interstadial of the Last Glacial, that is MIS3a or 40-22 kaBP, was a warm and wet stage. There was probably more precipitation at this interval than the present in South-east Monsoon area. In the Tibetan plateau there were more precipitation during 40-22 kaBP than the Megathermal Maximum in the Holocene reconstructed with hydrological and energy balance of closed lake basin. Evidence from gravel-sand bars around lakes shows that Huangqihai Lake have experienced high-level stage during 40-22 kaBP. These gravel-sand bars are mainly found at the foot of mountain, Libaisi northern hill and Gu hill, such as. At the Libaisi northern hill, the sand-bar, with a. s. 1 1 310-1 318 m, covered by stripe-like meadow, was dated 24.43 ～ 2.33 ka BP by OSL method. This paper calculated palaeo-precipitation of this stage in Huangqihai basin, in order to analyze the difference of precipitation in the monsoon area of eastern Asia and the Tibetan plateau. Based on the modern relief map, if the high lake level stand on the 1 310-1 318 m, 50 m higher than the present, Huangqihai Paleolake had an area of 450～515 km^2（average 466 km^2） , 4.4-5.1 times of that of the present （1950-1961A. D）. Using J. E. Kutzbach＇s equation of energy balance to compute the land evaporation and water surface evaporation with step-after-step approaching method to obtain the parameters, we modeled the combined hydrological and energy balance of Huangqihai basin, and the following estimates of precipitation were yielded： 479- 497mm/a during 40-22 ka BP, higher 126-144 mm/a than the present. But we do not think the precipitation is more than that of the highest lake level stage in Holoeene. The precipitation, however, in the Tibetan Plateau, was higher at 40-24 kaBP than at 14-4.0 ka BP. Certainly, the reestablished palaeo-precipitation, is only when the high lake level stand at a. s. 1 1 310-1318 m during some stage of 40-22 ka BP, not that of stage of 40-22 ka BP when lake level was lower than 1310-1 318 m.
出处
《沉积学报》
CAS
CSCD
北大核心
2005年第3期523-530,共8页
Acta Sedimentologica Sinica
基金
中国科学院知识创新工程项目(CXNGLASA012
KZCX2SW118)资助.
关键词
黄旗海
末次冰期间冰阶
古降水量
逐次逼近法
Huangqihai Lake, the interstadial of the Last Glacial, palaeo-precipitation, step-after-step approaching method
