摘要
对位于关中盆地的大荔地区甜水沟和垣雷两个剖面末次冰期 -间冰期旋回的碳酸盐和有机质碳同位素组成、磁化率和频率磁化率进行了系统研究 ,初步讨论了MIS 3后期 (即MIS 3a)的“高温大降水事件”对黄土高原南部气候和植被的影响。在 40～ 30kaB .P .的MIS 3a时期 ,大荔地区气候总体表现为湿润、温暖 ,植被覆盖程度高 ,植被中C4植物的相对含量增加 ,土壤发育较好。中国大陆黄土 -古土壤序列在MIS 3的磁化率较之末次冰期的其他时段均有所增加 ,但不同地区的增幅各不相同。
Malan loess was formed during the last glacial period, corresponding to MIS 2～4. In Tiansuigou and Yuanlei loess-paleosol sequence of the Dali area, Shaanxi provinces, Carbon isotopic ratios of carbonate in L 1-2 and L 1-4 are lighter than L 1-1, L 1-3 and L 1-5. Carbon isotopic ratios of organic matter in L 1-2 and L 1-4 are heavier than L 1-1, L 1-3 and L 1-5. Magnetic susceptibility and frequency magnetic susceptibility in L 1-2 and L 1-4 are higher than L 1-1, L 1-3 and L 1-5. The carbon isotopic ratios, the magnetic susceptibility and the frequency magnetic susceptibility obtained in the profiles show that the paleoclimate of this area was wetter and warmer during MIS 3 than during MIS 2 and MIS 4, but dryer and colder than during MIS 5. During 26～62ka B.P., MIS 3, the paleoclimate of MIS 3a was wetter and warmer than that of MIS 3b and MIS 3c. That is to say, in the period of MIS 3a, about 40～30ka B.P., the Dali area was humid and warm. So it can be deduced that the high temperature and large precipitation event recognized in the Tibet Plateau could also occurred in Loess Plateau, but the event in Loess Plateau was not so strong as in the Tibet Plateau. ; ;
出处
《第四纪研究》
CAS
CSCD
北大核心
2003年第1期69-76,共8页
Quaternary Sciences
基金
国家自然科学基金 (批准号 :4 989170 )
中国科学院知识创新工程 (KZCX2 - 10 3)
中国科学院地球化学研究所环境地球化学国家重点开放实验室基金资助项目
