摘要
研究陕西旬邑下墙完整的晚新生代红土 -黄土剖面后证实 ,磁化率也可以作为分析红土气候特征的一个替代性指标 ,但最好的办法是以磁化率为主 ,同时参考粒度、地球化学等资料进行综合分析。本区新近系红土的磁化率曲线特点是高频率、低幅度、短周期 ,第四系黄土 -古土壤的则是低频率、长周期。结合岩性、古生物、粒度及地球化学等资料得出 ,新近纪的气候在总体暖湿背景下有凉干 -暖湿的交替 ,而第四纪的气候则是在总体冷干背景下的冷干 -暖湿的交替。进入第四纪的气候突变及之后的气候亚突变 ,主导因素是该时期青藏高原的剧烈隆升 ,北极冰盖的形成与扩大也起着重要的作用。
The study of a complete late Cenozoic loess-red earth section in Xunyi County has proved that susceptibility could be used as a substitute index to analyze paleoclimate. The susceptibility curves of Neogene red earth are characterized by high-frequence, low-ampititute, and short-cycle, indicating an alternation of cool-dry and warm-humid phases against a generally warm-humid background, whereas the susceptibility curves of Quaternary loess are characterized by low-frequence and long-cycle, indicating an alternation of cold-dry and warm-humid phases against a generally cool-dry background. A key factor for Quaternary sudden climate changes and subchanges is intense uplift of the Qinghai-Tibet Plateau during that period, and the formation and amplification of Antarctic ice sheet could also have an important effect.
出处
《第四纪研究》
CAS
CSCD
北大核心
2003年第1期103-108,共6页
Quaternary Sciences
基金
国家攀登计划 (批准号 :95-预 - 40 )资助项目
关键词
陕西
晚新生代
红土
黄土
磁化率
环境变迁
Late Cenozoic, red earth-loess, susceptibility, environmental variation
