黄土地层精确时间标尺的建立——以三门峡黄土地层研究为例

TIME SCALE OF LOESS IN THE SANMENXIA AREA

厚度153m的曹村剖面出露了厚145m的完整黄土地层,为L1—L33的连续风尘沉积,为黄土高原东南部三门峡地区黄土地层的代表。建立曹村黄土地层的精确时间标尺,不仅能在千年时间尺度下探讨黄土高原古季风变迁,而且着眼于全球古气候变化开展海陆对比研究。本文对现有的4种时间标尺模式进行了介绍,应用磁化率模式和粒度模式开展了三门峡黄土时间标尺研究,并进行了校验,说明了几种模式建立曹村黄土时间标尺的可行性。

The 153 m thick Caocun loess profile at Zhangbian Township located at the southeast margin of the Loess Plateau is typical of the Sanmenxia area.In the profile there occurs a complete,145 m thick loess-paleosol sequence consisting of continuous dust deposits from L1 to L(33) 145 m thick.The establishment of an accurate time scale of the Caocun loess sequence is important not only for the study of (millenial-scale) paleomonsoonal change on the Loess plateau but also for the correlation of global paleoclimate changes between land and sea.In this paper four available time scale models are introduced and the time scale of loess in Sanmenxia is studied using the susceptibility model and grain-size model and checked.It is feasible to establish the time scale of the Caocun loess using several models.