华北克拉通东部南北缘中生代火山沉积格局及其构造转折过程

通过华北克拉通东部北缘和南缘盆地充填序列和盆地分布演化对比研究，解析了该区中生代构造转折过程。研究发现两侧盆地均大致从早侏罗世开始发育，约以晚侏罗世为界，之前盆地充填记录反映以挤压作用、岩石圈增厚为主，之后以陆内伸展、岩石圈减薄为主，显示晚侏罗世明显的构造转折，并且地壳浅部的构造体制转变均滞后于岩石圈深部构造环境的变化。然而，两侧盆地演化也有明显差别：①北缘燕辽地区从早侏罗世到白垩纪，发育了多层系的从基性、中基性到中酸性的火山岩及火山碎屑岩组合，而南缘合肥盆地仅在晚侏罗世早白垩世产出钙碱性火山岩及火山碎屑岩组合，反映出不同的深部构造过程和源区特征；②北缘的岩石圈减薄可能始于约163 Ma，南缘明显的岩石圈减薄则始于约149 Ma，而反映在盆地构造与充填尺度上的伸展作用分别对应于大约145 Ma和132 Ma；③晚侏罗世构造转折期，北缘燕辽地区粗碎屑沉积以河流体系为主，反映盆山地势高差较小；而南缘该期发育冲积扇体系，盆山地势高差较大；④北缘盆地沉积中心迁移规律复杂，而南缘总体呈现由南向北的迁移趋势。显然，大别山碰撞造山和后造山期强烈的隆升和剥露对南缘盆地演化具有极大的主导和制约作用，而北缘则显示出强烈的壳幔相互作用并伴有区域性的陆内挤压推覆（转折前）和张裂 伸展（转折后）交替的特点。华北克拉通晚中生代构造转折的时限北缘较南缘早，说明诱发这一转折事件的区域构造动力可能首先与华北北部壳幔相互作用密切关联。

Mesozoic volcanic-sedimentary configurations in north and south margins of the eastern North China Craton: Implications for tectonic transition mechanism

The Mesozoic basin-filling records and the basin distribution and evolution in the north and south margins of the eastern North China Craton are compared, and the Mesozoic configurations are constructed in this paper. The above basins are characterized by similar evolutionary processes: Develop since the Early Jurassic, the basin-filling evolution from a compressional and lithospheric thickening setting in the Pre-Late Jurassic to a intracontinental tension and lithospheric thinning setting after Late Jurassic, showing a tectonic regime inversion during the Late Jurassic with a time lag in shallow crust to deep lithosphere. However, the basin-filling records mentioned above also show distinct differences between the two basin systems. Firstly, multiplayer basic, medium-basic and medium-acidic volcanic-pyroclastic assemblages were developed in the north Yanshan-Liaoxi basins from the Early Jurassic to Cretaceous; but limited calc-alkaline volcanic series filled the south Hefei Basin during the Late Jurassic-Early Cretaceous. Secondly, the Late Mesozoic lithospheric thinning began at ca. 163 Ma and 149 Ma in the north and south margins, which finally resulted in ca. 145 Ma and 132 Ma structural extensional events in a basin-scale, respectively. Thirdly, coarse clastic sediments occurred in the north and south margins during the tectonic inversion phase (Late Jurassic) were mainly deposited as fluvial and alluvial facies, respectively indicating topographic difference in elevation evident in the south and nonevident in the north. Fourthly, the Mesozoic depocenter migration shows a complicated track in the north margin but an evident trend from south to north in the Hefei Basin. Therefore, it is presented that basin-filling records in the south margins of the eastern North China Craton were dominantly controlled by the uplift and exhumation which resulted from collisional orogenesis and post-orogenesis in the Dabieshan area. On the other hand, the north basin evolution shows a control mechanism induced from intensive crust-mantle interaction, with a regional basin-range stress transition from pressing-thrusting to spreading-stretching across the tectonic inversion phase. In addition, as mentioned above, the tectonic regime inversion of the North China Craton shows an earlier time limit in the Yanshan-Liaoxi basins than that in the Hefei Basin, which probably indicates that the Late Mesozoic inversion is firstly driven by a deep crust-mantle interaction in the northern North China.