华北陆台北缘中晚元古代坳拉谷

吕梁运动铸成的华北陆台地壳厚度增大，在地幔热柱上涌作用下陆台拉开，出现地堑盆地，发展演化为坳拉谷，自西至东为：①白云鄂博 化德坳拉谷，②渣尔泰 尚义 隆化坳拉谷，③燕山 汛河坳拉谷，④复州 太子河 浑江坳拉谷。每个坳拉谷内均为稳定－次稳定型的中上元古界。各地拉张幅度不同，岩相建造略有差异，均具有燕山型中上元古界特点，可以对比，显示各坳拉谷同步发展演化。

BASIC SEDIMENTARY CHARACTERS AND PALEOCLIMATIC IMPLICATIONS OF SALINE LAKES IN INNER MONGOLIA

In the saline lakes in Inner Mongolia, complete persistent sequences are lain of clast, clay mud and saline sediments. the clastic sediment gives informations of arid climate and poor vegetation when it deposited. In contrast with this is the clay mud which makes a diagnosis about conditions of warmness and wetness. The third sedement, massive mirabilite and natron, is products of a continuously arid, but intermittently seriously cold, climate. According to the researches on the sedimentary evalution of the saline lakes, the paleoclimate in Inner Mongolia has been characterized throughout the past 20000 years essentially by alternation of warmness wetness with coldness aridness. In this period, three prominent temperture dropping events took place between 15000 and 12000, 11000 and 10000,and 5000 later on.