摘要
广布于我国北方的新第三纪红层多由中新统保德组和上新统静乐组组成，这两个组岩性相似，一般情况下难以区分。地层结构详细研究显示，两组中钙质结核赋存方式相差很大，前者呈层状产出，后者为星散状，地层形成时古气候条件的差别是导致该现象的主要原因。由于大气状况具有区域性特点。
The earth sediments called Baode Formation or “ Hipparion Red Clay”are well developed in Shaanxi,Shanxi, Gansu,etc.It may be subdivided into two stratigraphic units,namely,Baode Formation(or Lantian Formation)(Upper Miocene)and Jingle Formation(Pliocene).The features of the fossil assemblages in the Formations are quite different.They have been regarded as one unit “ Hipparion Red Clay” and have seldom been subdivided since the Jingle Formation was set up because no interruption of sedimentation was observed them.Few fossils were found in the Jingle Formation.Both of two Formations were composed of purplish,pink red clay,silty clay with abundand carbonate nodules.The major differences between the two Formations are as follows:(1)the carbonate nodules in the strata occurs as nodule layer in the Baode Formation and as scattered specks or net veined form in the Jingle Formation; (2)the stratigraphic structures are different,the former shows the feature of layered structure and the latter shows the massive one; (3)the geomorphic features are diffierent,the former often exixts as precipitous because of the great resistance to weathering of nodule strum,but the latter generally forms the smooth relief; (4)the colors of the sediment between the two Formations are also different,the Jingle Formation essentially is fresh red and the pale yellow is the main color in the Baode Formation.All of differences mainly resulted from the different occurrence of the carbonate nodules in two Formations.As the characteristic mark of earth sediments,carbonate nodules may well correlate with climatic condition and ground water.The existence and the distributing feature of carbonate nodules have a certain geological significance.
出处
《地层学杂志》
CSCD
北大核心
1997年第1期63-67,共5页
Journal of Stratigraphy
关键词
上第三纪
静乐组
地层划分
古气候
岩石学
petrographic marks, stratigraphical division, Hipparion Red Clay, Jingle Formation, Baode Formation, Neogene
