【摘要】 黄河三门峡水库北岸的山西省平陆县黄底沟剖面，较完整地保存着古三门湖湖相沉积记录。经磁性地层研究结果表明，古三门湖沉积起始于吉尔伯特负极性时中期，大约在５ＭａＢＰ；结束于布容正极性时晚期，结合热释光年龄，大约在１５０ｋａＢＰ。鉴于古三门湖沉积地层从晚第三纪上新世早期延续至第四纪中更新世晚期。因此，我们将这套地层统称为三门群，并据其岩性特征自上而下划分为三段，上段以砂层为主；中段以粘土层为主；下段为底砾石层。黄底沟剖面是已知的记录古三门湖发育起始时间最早、结束年代最晚的地层剖面。更多还原

【Abstract】 The lacustrine deposits of the ancient Sanmen Lake have been preserved in good condition in the Huangdigou profile which is located at the north of Sanmenxia Reservoir in Pinglu County of Shaanxi province.From a study of the magnetostratigraphy,the deposition of the ancient Sanmen Lake is known to have started in the middle of Gilbert reversal polarity chron,about 5MaBP,and ended in the late of Brunhes normal polarity chron,about 150kaBP.Since the sedimentary sequence has persisted from the early Pliocene of Neogene to the end of middle Pleistocene of Quaternary,it is referred to as the Sanmen group.Based on the lithological characters,the sequence can be subdivided into three members,the upper member consisting dominantly of sand layers,the middle member of clay layers and the lower member of basal gravel.The series is now known to have the longest period of deposition that commenced earlier and terminated later than all the others.更多还原