摘要
在青藏高原东缘明显的分布着三个构造带,即:a.高原本体东缘的弧形构造带,由褶曲、断裂组成,弧顶均向南或南东突出,其排列多受高原边缘的限制;b.高原外前方的挤压隆起带,系由高原向东推挤产生的前方挤压隆起;c.推覆构造带,由高原向东超前蠕流部分叠覆于隆起带上形成。以上三个构造带又被两条南东向走滑断层切割成三段,使各段从北向南递次向东错移。造成这一构造格局的原因系由西藏地区受印度板块强烈挤压缩短时,物质发生大量向东蠕变流动引起的。
Many geologists believe that the Qinghai-Xizang Plateau has subjected to south-north compression. Due to this compression, theplateau material must have had lateral creep-flow to form a series of characteristic structures presently observed in the east margin. 1) Arcuate structural zone: It consists of arcuate folds and faults with apexes pointing to south or southeast and showing the materialcreep-flow to the same directions. 2) Frontal compression upwarping zone and nappe zone: The compression upwarping zone formed at the outlying front part of thecreep-flow, where Prepalaeozoic and Palaeozoic strata are often outcropped. Folds and thrusts are also common. Their axis-planes andfault-planes dip west. Nappes are observed in the area between the compression upwarping zone and the arcuate structural zone,wherethe plateau material creep-flowing eastward and overlaping onto the upwarping zone. 3) All the above mentioned three zones were successively displaced into three sections by a giant NW sinistral strike-slip. The dis-tance of displacement is 90-130km to SE. Development of this structural pattern is believed to have commenced at the end of Triassic, highlighted at Pliocene, and is being stillactive presently.
关键词
构造
变形
蠕变构造
青藏高原
Qinghai-Xizang Plateau
structural deformation
creep structure
arcuate structure
nappe structure
compression upwarping
strike-slip faults
