横断运动是指发生于吉尔伯特世与高斯世之间的地磁极性倒转期，覆盖着中国大部分区域的一次构造运动；青藏高原期则是指从横断运动开始的以青藏高原块状隆起为突出特征的地壳构造发展阶段，它相当于一般所说的新构造期。这是笔者在整理横断山系新构造调查所积累的资料，总结新构造基本问题过程中提出的。新构造运动在中国，尤其在中国西部的显现，以及新构造期从上新世末算起，已为众多的文献所论述(杨理华、刘东生，1974; 王乃梁，1981; 马杏元等，1987; 张宗站等，1990)。青藏高原大面积隆起开始于上新世末，业已为大量资料所证实(李吉均等.1979; 张青松等，1981; 李炳元等，1983)。显然，青藏高原隆起与新构造运动是密切关联的。以笔者的认识，一般所说的新构造运动或新构造期是地壳掬造发展最新阶段的总称，其中包含若干次构造变动;横断运动在这个阶段中为始发，也是最重要的一次构造变动$青藏高原块状隆起是横断运动引发的。因此，新构造运动与青藏高原隆起是地壳掏造演化中的因与果，横断运动与青藏高原隆起可作为新构造期亦即本文所称的青藏高原期的标志。

Acording to the data of lithostratigraphy , biostratigraphy and magnetostratigraphy in the southwest and north of China ,especially the imformation obtained in Hengduan Mountain System recently ,an important diastrophism is suggested to the early stage of Late Cenozoic. A set of fluvial-lacustrine facies in the graben basins which was dated from Gauss to Matsuyama epoch (wuch as Xigeda Formation in Sichuan , Yuanmou Formation in Yunnan , Nihewan Formation in Hebei and Yushe Formation in shanxi ,etc. ) are unconformably overlying on the Tertiary or Pre-Cenozoic , and along the unconformity surface developed a paleocrust of weathering of laterite type (Panzhihua red earth in Sichuan) or Hipparioll red earth (Baode Formation in Shanxi). Paleoenvironmental analysis of Hipparioll fauna and paleovegetation indicated that Western China (including Qinghai-Xizang region) remaied as peneplain with 500 -1000 m a. s. 1. generally. Until now , the paleocrust of weahering rises to 3670 m a.s.1. or buried under the basin (480 m a. s. 1. ) in diffrent places. The buried paleocrust of weathering represents a paleoplanation surface. The buried paleoplanation surface and the paleoplanation surface appeared at about 4500- 5500 m a. s. 1. of Western China belonged to a uIiited one , and then it was seperated by fault - block movement. The regional unconformity ,
the uplifting of Qinghai-Xizang CTibet) Plateau , the paleoplanation surface and also the deposition of graben basins occurred lately demonstrated the existence of an important diastrophism from the aspects of tectonics , stratum and landform , which was responsible for the uplifting of Qinghai-Xizang(Tibet) Plateau and the present pattern of landscape in China. For the major evidences which can support the exist of diastrophism in Hengduan Mountain System very popular. so we suggested that it can be named Hengduam Movement. The Movement is dated Gauss/Gilbert in geomagnetic polarity scale , about 3. 4 Ma BP. .

 

Hengduan Movement and the uplifting of Qinghai-Xizang (Tibet) Plateau which is started by the Movement marks the newest developing stage of crustal tectonics in geological term. The stage is characterized by tectonics landform ,Quaternary deformation, active faults and magmatic activities , but the most significance is the uplifting of Qinghai-Xizang Plateau. Therefore, it is suggested to take the name of Qinghai - Xizang Plateau Period, that is the neotectonic period.