基于GPS矢量的河套–银川盆地“橡皮楔”拖带与斜张模式论

The Movement Model of “Rubber Wedge” Towing and Oblique Tension of Hetao-Yinchuan Basin Based on the GPS Vector

摘要: 本文根据河套–银川盆地及围区的GPS矢量规律，经分析认为目前河套盆地正在NNW-SSE向伸展拉张。研究发现，从武威到临洮所经过的四个地块“威洮四块”存在明显的GPS矢量发散，“威洮四块”西部向北运动，东部向东运动，两个GPS矢量分道扬镳，陇西地块正在向东推挤鄂尔多斯地块。针对这些GPS矢量格局，河套盆地目前的运动可以用“橡皮楔”模式来解释，“威洮四块”遭受到SSW方向来源的挤压力作用，由于“威洮四块”塑性伸展，其东部拖动鄂尔多斯地块向东南运动，西部拖动阿拉善地块向NNW向运动，由于阿拉善地块和鄂尔多斯地块被拖曳的运动方向不同，导致了河套盆地和银川地堑目前的伸展成盆。这种刚性地块和造山带的塑性伸展关系可以理解为造山带的“橡皮泥”受到的垂向挤压转化成平行于造山带方向的伸展，“橡皮楔”模式可以解释目前河套–银川盆地的运动。银川地堑的形成过程中，并不是单一的“挤开式”或“拉开式”，而是“挤开式”和“拉开式”共同作用的结果，属于斜张成盆模式。河套–银川盆地及围区盆地是“橡皮楔”拖带与右行斜张共同作用的结果。

Abstract: Based on the GPS vector of Hetao basin and analyzing its surrounding area, the authors think that the Hetao basin is NNW-SSE stretching. The four blocks that range from Gansu Wuwei to Shanxi Lintao can be called “Wei-Tao four Blocks”. There is an obvious separation of GPS vectors in “Wei-Tao four Blocks”. The west part of them is moving towards the north and the central-east part is towards the east. The Longxi Block is pushing The Ordos Block to the east. The authors put forward the current movement that can be explained by “rubber wedge” tectonic movement model in Hetao basin. The authors think the “Wei-Tao four Blocks” results from the extrusion of the SSW direction, which causes the “Wei-Tao four Blocks” plastic stretch. The plastic stretch drags the Ordos Block towards the SE direction and the Alashan Block towards the NNW direction. Because of the opposite movement direction of the Alashan Block and the Ordos Block, the Hetao Basin and the Yinchuan graben come into being. The Yinchuan Graben is not formed by the single model of “extrusion-apart” or “pull-open”, but the composite model of “extrusion-apart” and “pull-open”. This model is an oblique-extension basin forming model. The Hetao-Yinchuan Basin and its surrounding basins are the result of the joint action of the “rubber wedge” and the right-lateral slip-extension.