青藏高原东北缘若尔盖盆地晚新近纪地层的多重划分与对比

以新构造运动为背景,以岩石地层特征为基础,以多种方法的测年数据为依据,以生物化石种属与产出层位和气候地层为参考,按照多重地层划分观点,本文首次对若尔盖盆地更新统及全新统的生物地层、气候地层和年代地层的划分做了深入研究,进而提出了若尔盖盆地晚新近纪地层的多重划分与对比方案.在以新构造运动为背景下沉积的更新统一全新统生物地层、气候地层等在不同发展阶段具有不同的特征,相同时期不同沉积物之间可以相互对比.利用植物、孢粉和测年数据,"阿坝砾石层"时代划归为早更新世.黄河干流、黑河和白河地层中所产古脊椎动物化石和介形类化石的地质时代为晚更新世.由泥炭孢粉剖面和RM孔孢粉资料揭示出晚冰期到冰后期以来,若尔盖地区的气候表现出极大的不稳定性,冷暖变化频繁,可与由冰期与间冰期或干旱期与湿润期交替演进的气候地层划分的中更新世4366高地冰期和尼格曲一公巴拉克冰期,晚更新世末次冰期早期的木哈隆冰阶、扎尔吉冰阶、羊拱海冰阶、希门错沟冰阶和末次冰期晚期的安纳尔冰阶、全新世冰后期气候地层单位,以及河流堆积阶地划分和风成堆积划分相对应.

Stratigaphic multiple classification and correlation of Late Neogene deposits in the Zoige Basin,northeastern margin of the Qinghai-Tibet plateau

In the light of stratigraphic multiple classification,the paper, based on field surveys,laboratoey datings and a background of neotectonic movements,studied synthetically and systemitally the lithostratigraphy,biostratigraphy,climatostratigraphy and chronostratigraphy of Late Neogene deposits in the Zoigê Basin in northeastern margin of the Qinghai-Tibet plateau.Our study revealed that the vegetation,glaciation and climate changing were constrained by rising of the plateau,so the strata with varied sedimentary fades could be well correlation.Furthermore,a scheme on stratigraphic multiple classification and correlation of the Late Neogene deposits in the basin and its environs was presented in the paper.And we also learned the following knowledges.1)The Aba conglomerate layer should be in an age of Early Pleistocene.2) The fossils of vertebrate and Ostracoda from the Yellow River, Heihe River and Baihe River indicated an age of Late Pleistocene.3)The glacial activities could be divide into 4 epochs in Zoigê area, namely, the Highland 4366 and Nyigê Qu-Gongbalake Glaciations in Middle Pleistocene, the Last(Qomolangma)Glaciation in Late Pleistocene and the modern glaciation in Holocene.4)The climate in Zoige area displayed an extreme instability from late glacial epoch to post glacial epoch,with temperature rising and falling frequently.5)The glacial deposits could be well correlation with the sediments on river terraces and the eolian deposits.