极移与构造运动
PALAR WANDER AND TECTOGENETIC MOVEMENT
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摘要: 真极移现象已由古地磁学家观测到,数量级约为1°/Ma,它还得到流变学的证明。一个大陆的视极移减去真极移等于该大陆在地幔上的运动。笔者用真极移模型研究了华北中生代地壳运动,其结果与地质证据相容。此外还求出200Ma以来华北陆块的纬度变化和方位角变化,得出华北陆块受地幔的作用使纬度变化比其方位角变化稍大,证明华北大地构造有其方向性特征。Abstract: The large displacements of the Earth rotation axis with respect to the entire mantle on a geologic time-scale, called true polar wander (TPW), is detected by paleomagneticians, and its order of magnitude is about 1°/Ma.TPW is supported by mantle rheology. Apparent polar mantler (APW) of a continent minus TPW equals motions of this continent across the mantle.The author has studied Mesozoic crustal movements in North China with the TPW model, with the result that the variation of the latitude is greater than the variation of the azimuth relative to the mantle for North China Block since 200Ma.This is compatible with geologic evidence.It indicates the tectonic structures of North China had been definitely oriented.And the arc structures with the apex facing the south will have a different explanation for their existence with the TPW model than with the rotational deformation model.
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