摘要
泥河湾盆地井儿洼剖面古地磁测年结果全部为正向极性 ,剖面顶面下 3.0 8m处白垩质粘土层铀系不平衡法测年结果为 (50 6 0 0± 6 70 0 )aBP ,据此确定其磁性地层学时代为布容正向极性时 .剖面底部未出露B/M界限 ,说明地层时代晚于 78万aBP .依据磁性地层学特征 ,井儿洼剖面可与虎头梁剖面对比 ,并能与红崖南沟、大道坡、郝家台等剖面的上部或顶部对比 ,属泥河湾组Ⅲ段 .井儿洼、虎头梁剖面下部的石膏沉积晚于红崖、铺路等剖面下部的石膏沉积 ,它们分属不同的石膏沉积旋回 .井儿洼剖面出露的湖相地层记录了古湖的消亡过程 。
The results of paleomagnetic measurements of 219 samples from an outcrop of 54.19 m at Jingerwa in Nihewan basin show normal polarity features. U series dating of chalky clay sample at 3.08 m from the top of the profile is 50 600±6 700 a BP, which confirms that the magnetostratigraphic date of it is Brunhes normal polarity chron. As the B/M boundary is not exposed at the bottom of the profile, the deposits are formed after 78×10 4 a BP and belong to the third part of Nihewan group. Based on magnetostratigraphic features, Jingerwa profile can be correlated with Hutouliang profile, and correlated to the upper parts of Hongya Nangou, Dadaopo, Haojiatai profiles etc in Nihewan. The gypsum deposits in the lower parts of Jingerwa and Hutouliang are younger than those in the lower parts of Hongya and Pulu profiles. They belong to different gypsum depositing cycles. The lacustrine deposit exposed at Jingerwa is the youngest part of Nihewan beds and has recorded the last history of Nihewan lake.
出处
《北京师范大学学报（自然科学版）》
CAS
CSCD
北大核心
2001年第1期137-142,共6页
Journal of Beijing Normal University(Natural Science)
基金
国家自然科学基金资助项目 !(4 94710 6 7)
