东秦岭造山带莫霍面展布与碰撞造山带深部过程的关系

根据P波走时反演重建的三维速度图像，研究东秦岭造山带莫霍面的展布性态结果表明，在华北板块南缘潼关-登封-阜阳-线、商丹主缝合带北侧卢氏-奕川-方城-信阳-线和扬子板块北缘佛坪-陨西-武当山-枣阳-线莫霍面沿着造山带走向呈带状隆起而介于这三条带间，莫霍面均不同程度地下陷因此，东秦岭造山带在岩石圈缩短方向上莫霍面的展布目前仍然存在着很大的非均一性结合造山带地质、岩石地球化学和同位素年代学综合分析，认为造成莫霍面这一展布格局，主要与该碰撞造山带在不同演化时期各岩石构造单元中发生不同性态的岩石圈-软流圈和壳-幔间物质与能量的相互作用方式不一所造成的大陆动力学过程不同有关加上碰撞期后造山带深部岩石圈均衡在不同岩石构造单元中的差异，形成了东秦岭造山带目前莫霍面的展布。

THe MORPHOLOCY OF MOHO DISCONTINUITY AND IT'S EVOLUTION GEODYNAMICS IN THE EASTERN QINLING COLLISIONAL OROGENIC BELT

Based on the 3-D seismic velocity images reconstructed from seismic tomographic tecdnique, the present authors outlined the morphology of Moho discontinuity in the eastern Qinling collisional orogenic belt. Conclusively, the distribution of Moho discontinuity in the mountain ranges is in the form of heterogeneity in the direction of mountain collision. Which is characterized by that the Moho discontinuity is relatively uplifted in the two sides of the main suture zone, namely along the Tongguan-Denfen-Fuyang, Lushi-Ruanchuan-Xinyang and along the Fuping-Yunxi-Zaoyang. Between these uplifted belts, the Moho discontinuity is relatively subsided along the Shangzhou-Lushan-Zhurnadian in the north,and along the Shangkian-Neikian in the south. By researches on the collisional tectonics in different tectono-stratigraphic units, the geochemistry and the isotopic chronology of the post-collisional volcanic rocks, the continental geodynamic processes to form the unique distribution of Moho discontinuity has been discussed. In the north border of the adn suturesone, the uplift of Moho discontinuity is banly caused by the post-collision geodynamic processes, which are derived from the upsurge of asthenospheric mantle owing to the break-off of relative cold slab from the mountain root with the increasing of negative buoyancy. Whereas the uplift of Moho discontinuity in the southern border of the main suture sone is mainly related to the geodynamic processes of the mantle-derived continental margin rifting developed before the collision between the north China plate and the Yangtse plate. Owing to the continental margin rifting, the lithosphere in the belt was thinned and the Moho was initially domed. In the processes of mountain building, the uplift of Moho discontinultyhad been intensified by the geodynamcs of lithospheric budge with the effect of tectonic inversion from extensive rifting to compressive thrusting. Under this geological conditions, the morphology of Moho discontinuity in eastern Qinling collisional orogenic belt had been evaluated.