若尔盖与西秦岭地震反射岩石圈结构和盆山耦合

松潘地块北缘的若尔盖盆地与西秦岭造山带相接触，构成青藏高原东北缘典型的新生代盆山构造.其岩石圈结构与深部构造关系，记录了青藏高原东北缘板块碰撞的深部过程，同时又关联着若尔盖盆地油气远景的评价.2004年秋冬季，我们完成了第一条跨越若尔盖盆地和西秦岭造山带的深地震反射剖面.整个剖面全长254 km，分5段完成，其中第2段剖面（简称SP04_2）横过盆山结合部位.SP04_2剖面首次揭示若尔盖盆地－西秦岭造山带盆山结合部位的岩石圈结构，发现了若尔盖盆地和西秦岭造山带下地壳均以北倾为主的强反射特征，提供出若尔盖盆地下地壳整体向西秦岭造山带俯冲的地震学证据，揭示了若尔盖盆地和西秦岭造山带在挤压构造体系下形成的深部构造关系.而近于平的Moho反射特征又反映出两者在造山后期经历了强烈的伸展作用.

Basin-range coupling and lithosphere structure between the Zoige and the west Qinling

The Zoigê basin on the north boundary of the Songpan block contacting with the west Qinling orogen, is a typical Neozoic basin range structural pair on the northeastern margin of the Qinghai Tibet plateau. The lithosphere structure and the deep structural relationship of the plateau boundary with basin range pair not only establishes the foundation for studying the collision of blocks in the northeastern margin of the Qinghai Tibet plateau, but also relates oil and gas resource evaluation. Therefore, the first deep seismic reflection profile about 254 km long being five segments across the Zoigê basin and the west Qinling orogen is completed in 2004,whose second segment (SP04_2) cross the basin range contact zone. SP04_2 reflection profile has disclosed for the first time the structure of the whole crust and the upper mantle in the basin_range boundary zone in the northeastern margin of the Qinghai_Tibet plateau, and has discovered a north dipping strong reflection. The north dipping reflection constitutes seismic evidence for underthrusting of the Zoigê basin by the west Qinling orogen. The seismic profile preliminarily reveals the structural relationship between the Zoigê Basin and the west Qinling orogen at lithosphere scale during Tibetan extrusion. The almost horizontal reflection from the Moho suggests that the Zoigê basin and the west Qinling orogen underwent intensive extension during the post_orogenic period.