大别山造山带与安徽沿江中新生代盆地的盆山耦合关系

Basin-Range coupling between the Dabie orogen and the Meso-Cenozoic basins along the Yangtze River in Anhui Province

安徽沿江中新生代盆地位于大别山造山带南缘,为先挤压、后伸展形成的叠合盆地,是探讨扬子板块陆内深俯冲—大别山造山带隆起与中、下扬子盆地沉降的耦合关系的理想场所。在早中生代,大别山为华南和华北大陆碰撞造山带,华南地壳向深处俯冲并承受超高压变质作用,超高压变质岩不断向上折返,沿江坳陷具有前陆盆地性质,盆地充填有晚三叠世—中侏罗世磨拉石层序;在晚中生代,在中国东部整体的拉张背景下,大别山变质带完全折返上隆,处于变质核杂岩隆升状态,而沿江坳陷具有裂陷盆地性质,充填有晚侏罗世—早白垩世、晚白垩世—古近纪两个红色碎屑构造层序,起因于地壳拆沉而产生的均衡隆升和伸展断陷的构造耦合。

The Meso-Cenozoic basins along the Yangtze River in Anhui Province are located at the southern margin of the Dabie orogen.They are overlapped basins formed by compression and then by extension.These basins are ideal sites for the study of the coupling between the uplift of the Dabie orogen and the subsidence of the basins in the middle-lower Yangtze River region.In the Early Mesozoic,the Dabie Mountains area is a col-lisional orogen between the South and North China continental blocks.The South China continental crust was subducted to great depths and underwent ultrahigh-pressure metamorphism.Then the ultrahigh-pressure meta-morphic rocks were exhumed progressively to the surface.The depressions along the Yangtze River is of foreland basin nature,which are filled with Late Triassic-Middle Jurassic molasses.In the Late Mesozoic,in the wholesale extensional setting in eastern China,the Dabie metamorphic belt was entirely exhumed and was in a regime of metamorphic core complex.On the other hand,the depressions along the Yangtze River is of rift basin nature,which are filled by Late Jurassic to Early Cretaceous and Late Cretaceous to Paleocene red clastic sequences.These clastic sequences were formed as a result of the coupling of isostatic uplift and extensional rifting.