辽河断陷中元古代构造演化

Mesoproterozoic Tectonic Evolution of Liaohe Fault Depression

摘要:

辽河断陷的中元古代构造演化与华北北缘和郯庐断裂带的构造演化密切相关。大红峪期，华北北缘在大陆裂谷的基础上进一步发展成被动大陆边缘，郯庐断裂带随之响应发生张裂接受沉积。之后海平面升降，辽宁境内表现为杨庄上升和凌源上升，其不整合面均为沉积属性，在这期间，郯庐断裂带与华北北缘一致保持着裂解趋势。由兴城上升至芹峪上升，辽河断陷沉积了大红峪组、高于庄组、杨庄组和雾迷山组，洪水庄组和铁岭组尚待确定。芹峪上升表示华北北缘开始由被动大陆边缘转换成主动大陆边缘，洋壳低角度俯冲使华北北缘挤压抬升并迫使华北克拉通向南挤压，NE向郯庐断裂由张裂转换成挤压滑动，辽河断陷抬升遭受剥蚀。辽河断陷内的杨庄组和雾迷山组可能就在这一时期剥蚀殆尽。随后洋壳高角度俯冲，华北北缘形成弧后盆地，辽河断陷与燕山地区一样沉积下马岭组。蔚县上升为华北北缘陆陆碰撞造成，陆陆碰撞使华北北缘再次抬升，郯庐断裂挤压走滑增强，辽河断陷褶皱抬升，下马岭组遭受剥蚀。直到罗迪尼亚大陆开始裂解，郯庐断裂带再次张裂，辽河断陷沉积长龙山组和景儿峪组。

Abstract:

Tectonic evolution of Liaohe fault depression is closely related to tectonic evolution of northern margin of North China and Tanlu fault belt in Mesoproterozoic period. In Dahongyu period, the northern margin of North China have a development of a passive continental margin on the basis of the continental rift. Along with the evolution of northern margin of the North China, tensional fracture and sedimentary happened in Tanlu fault belt. Then sea level rise and fall, and the surface in Yangzhuang and Lingyuan rise in Liaoning province. Its unconformity has the deposition attributes. In this period, Tanlu fault belt and the northern margin of the North China still keep splitting tendency. From Xingcheng rise to Qinyu rise, Liaohe rift deposited Dahongyu formation, Gaoyuzhuang formation, Yangzhuang formation and Wumishan formation; while Hongshuizhuang formation and Tieling formation still need to be determined. Qinyu rise shows that the northern margin of North China began from the passive continental margin converted to active continental margin. The low angle subduction of oceanic crust maked the northern margin of North China extrusion and uplift, and forced the North China craton move to the south, north and east Tanlu fault belt by splitting into extrusion and sliding. Liaohe rift was lift and suffered from erosion. Yangzhuang formation and Wumishan formation may be eroded during this period in the Liaohe rift. Along with the high angle subduction of the oceanic crust, the northern margin of North China forming backarc basin, Liaohe rift deposited Xiamaling formation as Yanshan area. Weixian rise was caused by continental collision, and maked the northern margin of North China rise again. The extrusion and strikeslip of Tanlu fault zone become stronger, Liaohe rift folded and uplifted, and Xiamaling formation suffered from erosion. Utill Rodinia began to crack, Tanlu fault belt cracked again, Liaohe rift deposited Changlongshang formation and Jingeryu formation.