华北地块北缘中新元古界沉积构造演化

Sedimentary and Tectonic Evolution of the Meso-Neoproterozoic Strata in the Northern Margin of the North China Block

根据文献资料及对研究区8条实测剖面资料的综合分析结果表明,Columbia超级大陆的裂解导致华北陆块北缘大陆裂谷盆地的形成。随着大陆进一步伸展和洋壳的形成,华北地块北缘逐渐发展为被动大陆边缘。在1400Ma左右,即铁岭组沉积后,华北地块北缘转变为活动大陆边缘。早期洋壳向华北地块低角度的俯冲造成弧后地区发生挤压(芹峪上升),导致铁岭组抬升和剥蚀,而后期洋壳高角度的俯冲又造成弧后区域发生强烈的伸展和断陷,沉积了下马岭组,并伴随辉绿岩的侵入。华北地块与相邻地体之间的碰撞导致下马岭组的抬升(或蔚县抬升)以及碰撞花岗岩的形成,挤压构造发生的时间对应于Rodinia超级大陆的形成期。新元古代沉积是Rodinia超级大陆裂解的结果。龙山组石英砂岩和海绿石砂岩是Rodinia超级大陆裂解后的最早期沉积,记录了海侵初期的超覆过程。

The formation of continental rift basin in the northern margin of the Noah China block is caused by the breakup of the Columbia supercontinent according to previous study and analysis of our eight measured sections. Due to the continued crustal extension and creation of oceanic crust, the northern Noah China block involved into a passive continental margin, which then turned into an active margin around 1400 Ma after the deposition of the Tieling Formation. The low-angle subduction of the oceanic crust beneath the North China block resulted in a compression environment in the back-arc area （Qinyu Uplift）, thus leading to the uplift and erosion of the Tieling Formation. Presumably, high-angle subduction of the oceanic crust followed, and caused intense rifting and deposition of the Xiamaling Formation accompanied by the intrusion of diabase dykes. The uplift of the Xiamaling Formation （or Yuxian Uplift） was related to the collision between the North China block and the adjacent block, accompanied by occurrence of the collision-related granites. The time of contractional event coincided with the formation age of the Rodinia supercontinent. Neoproterozoic successions might be related to the breakup of the Rodinia supercontinent. Quartzarenites and glauconitic sandstones of the Longshan Formation is the earliest deposition after the breakup of the Rodinia supercontinent, recording the early transgressive processes.