冀东青龙一带中元古代盖层与太古宙基底滑脱构造的厘定及其地质意义

Tectonic detachment zone between the Archean basement and the Mesoproterozoic cover rocks in the Qinglong region, eastern Hebei, China, and its implications

在区域地质调查的基础上,通过对构造、岩浆岩和构造岩的详细研究,厘定出冀东青龙一带太古宙基底与中元古界盖层之间的接触关系为构造滑脱关系。构造滑脱经历了明显的2期活动,早期为挤压体制下的逆冲-褶皱作用,中元古界表现为同倒转褶皱,滑脱带内发育断层泥和断层角砾岩;晚期为伸展体制下的伸展滑脱作用,表现为断层泥劈理化发育,指示明显的伸展滑脱特征。研究区太古宙基底与中元古界盖层滑脱构造的厘定,对再造该区的构造格局和沉积古地理格局具有重要意义。

Based on regional mapping, tectonic analyses and distribution of igneous rocks, together with studies on tectonic rocks, we infer that there is a tectonic detachment zone between the Archean basement and the Mesoproterozoic cover rocks in the Qinglong region, eastern Hebei Province. This detachment event probably underwent two dististinguished periods. The earlier period is characterized by overturned homoclinal folds, and fault gouge and breccia are formed in the detachment zone due to thrust-folding process. The later period shows a detachment process, in which the fault gouge was cleavaged. Determination of the detachment contact between basement and cover rocks is of importance to paleogeographic reconstruction in this region.