【摘要】 若尔盖盆地和西秦岭造山带作为青藏高原东北缘典型的新生代盆山构造,其接合部位的岩石圈结构及其深部构造关系为青藏高原东北缘板块碰撞的深部过程等研究奠定基础。横过盆山结合部位的深地震反射剖面长约63km,记录时间30s(TWT),探测深度超过莫霍面深达岩石圈地幔。该剖面首次揭露出青藏高原东北缘的盆山结合部位地壳和上地幔盖层的结构,发现了若尔盖盆地和西秦岭造山带下地壳以北倾为主的强反射特征,这种北倾的反射特征提供了若尔盖盆地俯冲到西秦岭造山带之下,而西秦岭造山带逆冲推覆到若尔盖盆地之上的地震学证据,初步揭示出若尔盖盆地和西秦岭造山带在挤压构造体系下形成的岩石圈尺度的构造关系,近于平坦的Moho反射特征反映两者在造山后期又经历了强烈的伸展作用。更多还原

【Abstract】 The Zoigê basin and the west Qinling orogen constitute a typical basin-range structural pair on the northeastern margin of the Qinghai-Tibet plateau. The lithosphere structure and the deep structural relationship between the plateau boundary and the basin-range pair have laid the foundation for studying the collision of blocks on the northeastern margin of the Qinghai-Tibet plateau. A deep seismic reflection profile across the Zoigê basin and the west Qinling orogen about 63 km long had a recorded time length up to 30s (TWT), with the data reaching the mantle depth. The profile disclosed for the first time the structure of the whole crust and the upper mantle in the basin-range boundary zone on the northeastern margin of the Qinghai-Tibet plateau, and discovered a north-dipping strong reflection. The north-dipping reflection constitutes seismic evidence for the underthrusting of the Zoigê basin beneath the west Qinling orogen. The seismic profile preliminarily reveals the structural relationship between the Zoigê Basin and the west Qinling orogen during Tibetan extrusion at the lithosphere scale. The nearly horizontal reflection from the Moho suggests that the Zoigê basin and the west Qinling orogen underwent intensive extension during the post-orogenic period.更多还原