【摘要】 <正> 渭河盆地位于秦岭和渭河北山之间。秦岭与渭河平原接触线是一条长350公里、断距近万米,依次北降的阶梯状断裂带。高差近千米的渭河北山与渭河平原接触线是一条长300余公里,断距大于千米,依次南降的断裂带。因此,渭河盆地是一个地堑构造(图1)。更多还原

【Abstract】 The Weihe River Graben consists of seven tensile fracture belts, of these, the 1st, 2nd and 3rd (from south to north) formed on the Archean-Proterozoic basement and are zigzag tenso-shearing fractures, while the 4th to 7th formed on the Paleozoic basement and are arcuate in form. A number of earthquakes are genetically related with them. Examples are the 1556 Huaxian earthquake (related with the 4th fracture belt) and the 780 B. C. Qishan earthquake (related with the 7th fracture belt). There occur a series of hot springs along these fracture belts.The graben began to form in the late Eocene and has been active up to now. The graben is asymmetrical and controlled sedimentation and magmatie intrusion during the Cenozoic. The Cenozoic sediments are more than 6800m thick in its southern part, whereas in its northern part they are ouly less than 1000m. Along the 1st and 2nd belts a few Cenozoic granite intrusions have been found underground.更多还原