秦岭与桐柏-大别山的构造关系——兼论河淮盆地的构造演化

THE TECTONIC RELATIONSHIP BETWEEN THE QINLING MOUNTAINS AND TONGBAI-DABIE MOUNTAINS WITH NOTES ON THE TECTONIC EVOLUTION OF THE HEHUAI BASIN

原信阳群南湾组中已发现丰富的微古生物化石,其地质时代和沉积-构造特征与秦岭的泥盆系刘岭群一致;二郎坪群中已发现丰富的早古生代微古生物化石和少量珊瑚化石,其沉积序列基本显示了由海底扩张到洋盆消减的全过程。秦岭与桐柏-大别山各构造带之间可以彼此衔接,主缝合带位于丹凤-信阳-舒城-线。原信阳群龟山组就是沿主缝合带分布的前泥盆纪强应变构造地层体。同位素年代学的系统研究结果,充分反映出秦岭是一个加里东、华力西、印支、燕山多旋回复合造山带。中朝准地台南缘震旦-三叠系的沉积序列从另一个侧面反映了秦岭造山带的演化过程。白垩-第三纪河淮盆地是在特提斯与太平洋动力学体系联合作用下形成的。

Abundant microfossils have been found in the Nanwan Formation of the former Xinyang Group, which is consistant with the Devonian Liuling Group in the Qinling Mountains in age and sedimentary-structural characteristics. Also, abundant Early Paleozoic microfossils and a few corals have been discovered in the Erlangping Group, whose sedimentary sequence represents the process from sea-floor spreading to subduction of the ocean basin. The tectonic zones of the Qinling Mountains and the Tongbai-Dabie Mountains may link up one another, and the main suture zone is situated along Danfeng-Xinyang-Shucheng. It is the Guishan Formation of! the former Xinyang Group that is the strongly deformed pre-Devonian tectono-stratigraphic unit distributed in the main suture zone. The result of the systematic, isotopic dating clearly shows that the Qinling Mountains are a Caledonian, Variscan, Indosinian, and Yanshanian polycyclic composite orogen. The Sinian to Triassic sequence on the southern edge of the Sino-Korean platform has recorded the evolution of the Qinling orogen in different aspects of its process. The Cretaceous-Tertiary Hehuai basin was generated owing to the combined effect of the Tethys and Pacific Ocean dynamic systems.