论文部分内容阅读
来自东亚夏季风北界内蒙古一个盐湖的岩心沉积物内发现粗粒沉积物 ,既可沉积在湖泊收缩期 ,也可以沉积在沙丘再次活动时期。这些沉积物有机磷含量低而碎屑组分高 ,说明它沉积在一种干旱的环境中 ;反之 ,有机质含量高而碎屑组分低的细粒沉积物则最终沉积在高湖面期 ,这是因为砂坪呈围迁状态及风成尘埃较好地保存于水体中。所揭示的三个湿期分别是 13.4～ 8kaBP、6 .4～ 5 .8kaBP和4.2～ 3.1kaBP ,第一期最湿 ,其次是第三期、第二期。上述干和湿期自始至终和早先发现的同一个干旱和半干旱转换带一致 ,但是 ,这和中国大陆东部、台湾岛、冲绳海槽和中国南海所揭示的湿润的全新世大暖期不一样 ,而且 ,全新世最冷期 (4～ 2kaBP)则对应内蒙古的一个湿期 (即 4.2～ 3.1kaBP) ,这些差别可能是由于高蒸发量远远地超过了较高的季风降水量 ,这是确定夏季风北界在该地区有效湿度的一个关键标志。
Coarse sediments are found in the core sediments of a salt lake in the northern part of the East Asian summer monsoon zone of Inner Mongolia, either during lake systole or during re-activity in the dunes. These sediments are low in organic phosphorus and high in detritus, indicating that they are deposited in arid environments; conversely, fine-grained sediments with high organic matter and low detrital components are eventually deposited on the high lake, Because the sand was subsided state and the wind into the dust well preserved in water. The three wet periods revealed were 13.4 ~ 8kaBP, 6.4 ~ 5.8kaBP and 4.2 ~ 3.1kaBP, respectively. The first period was the wettest, followed by the third period and the second period. The above dry and wet periods are consistent with the earlier arid and semi-arid zones found earlier, but this is not the same as the humid Holocene Holocene revealed by eastern China, Taiwan Island, Okinawa Trough and South China Sea, Moreover, the Holocene collimator (4 ~ 2 ka BP) corresponds to a wet period in Inner Mongolia (4.2 ~ 3.1ka BP). These differences may be due to the fact that the high evapotranspiration far exceeds that of the higher monsoon rainfall, which is determined A key sign of the effective summer humidity in the northern boundary of the region.