赤峰西部高原第四系沉积环境初探

Approach to the Quaternary Sedimentary Environment of West Chifeng Plateau

下更新世本区地壳上升,气候干热。中、晚更新世总计有四次湖水出现,沉积有总厚度150多米的湖积砂;有4次河流出现,遗有50～80余米的冲积砂。每次湖水出现前均以河流作用为主,伴以地壳相对下降或稳定,气候干热。地壳上升气候湿冷。地壳升降,气候变化,河湖交替出现,贯川整个中、晚更新世。全新世地壳上升,湖水萎缩形成许多小湖泊,河谷窄切深大流程短。气候干冷以风作用为主,其南部被风少覆盖是小腾格里沙漠的一部分。

Influenced by bath the coustal movement and the climatie fluctuation, the sedimentary environment has occured alternately as fluvial and lake within the area of West chifeng Plateau since Quaternary.With the uplift of crust, it can be divided into five sedimentary stages under cold climate, in which fluvial deposits formed dominantly (not include the 5th stage) .The so and δi of the sediments in the first stage are higher than other stages. It shows strong hydrodynamic and the bad sorting. Because of the inrich of unstable mineral in eaeh cold stage, the associate section of unstable nrineral is easly seen (K< K) except a part of K> K, which causeel by climatie fluetuation.Most of the traee elemeuts are dispersed and a few are concentrated in every stage.This phenomenon is related to source of materials besides the influence of climate in our opinion.The temperature in the third stage is higher than the fourth. Similarily, it can be divided 5 sedimentary stages under Warm climate, when the crust descents or. stable relatively.The lacustrine seelimentation played a leading role in evey warm stage with the exception in the first one.Because of the inrich of stable minerals in each warm stage, the association seetions of stable minerals exist in the mineral content curve (K > K) except a part of K < K which coused by climatie fluctuation. The most of the trace elements are concentrateed and only a few are scattered as a result of the warm-humid climate and rapid deposition. Aceording to the materials on hand, the fourth and fifth warm stages helong to fresh-water or light salt-water environment.