阜平地区太古宙地壳变形序列及演化

Archaean crustal deformation sequence and its evolution in Fuping Area

阜平地区的太古宙地壳，主要由变质表壳岩和变质深成岩（约占５０％）组成。变质表壳岩即阜平岩群可分为上、下两个岩组：下部叠卜安岩组；上部宋家口岩组。变质深成岩分为钠质和钾质两个系列。在其形成和发展演化过程中经历了三期褶皱变形及其相伴的两期韧性剪切变形：第一期褶皱变形发生于下部表壳岩麻粒岩相变质阶段；第二期褶皱形成于钠质深成岩侵位之后；第三期褶皱群形成于太古宙末期。在二、三期褶皱变形过程中形成两期韧性剪切带。他们共同造就了阜平穹状复合褶皱群的构造面貌。

rchaean crust in Fuping area is mainly composed of metamorphic supracrustal rocks and metamorphic plutonic rocks (about 50 percent in outcrop area). Metamorphic supracrustal rocks e. g. Fuping Group, is divided into two subgroups:the lower subgroup (Diebuan formation) and the uppersubgroup (Songjakou farmation)' The former is made up garnet-rich leptinite, plagioclase amphibolite, granulite and pyroxene- magnetite quartzite. Whereas the latter is composed of leptite. leptynite, amphibolite, calc-silicate rocks and marble. There are two series of metamorphic plutonic rocks. e. g, sodic and potassiac rocks. This region experenced three stage of fold deformation and the concurrent two stage of ductil shearing deformation. The first stage deformation occurred in the same time as the granulitic face metamorphism of the lower supracrustal rocks.The second stage of fold deformation took place after the intrusion of sodic rocks.The third stage of deformation. E-W-trending folds, were formed at the late Archaean.Two stage of ductile shearing deformation are coincide with the last two stage of deformation,respectively.All these process lead to the formation of the Fuping dome multiple folding system.