文-威地区胶南造山带根部的韧性剪切系统

DUCTILE SHEAR SYSTEMS IN THE ROOT OF THE JIAONAN OROGENIC BELT IN THE WEN-WEI AREA

摘要:

胶东文-威地区的胶南造山带，属秦岭-大别-胶南造山带的北东段，区内广泛分布着规模巨大的前寒武纪中、深构造相韧性剪切系统。按其形成序列及方式，大致可分为3种；①近水平伸展式韧性剪切系统，变形机制以位错滑动、位错蠕变为主。其变质的温压条件T为630～680℃，P为0．67GPa，剪应变值平均为4．47，形成时的差异应力为44．57～79．5MPa。形成于中元古代造山带演化早期的伸展裂陷阶段。②收缩挤压式韧性剪切系统，变形机制以粒间边界滑移为主。变质的温压条件T为600～700℃，P为0．77～0．85Gpa。剪应变值为1．2～2．1，形成时的差异应力为62．22MPa。形成于新元古代早～中期造山带挤压抬升阶段。③逆冲推覆式韧性剪切系统，变形机制以位错滑动，位错蠕变为主。变质的温压条件T为514℃，P为0．77GPa。其剪应变值为3～5，形成时的差异应力为69．96～85．76MPa。形成于新元古代中期造山带逆冲推覆造山阶段。

Abstract:

Jiaonan orogenic belt in the Wen-Wei area belongs to the northeast section of the Qinling-Dabie-Jiaonan orogenic belt-In the area,jiant Precambrian ductile shear systemsof middle-deep tectonic facies are well developed. According to the sequence and ways offormation,they can be classified into three types,①Horizontally extentional ductile shear system: the deformation mechanism is featuredmainly of dislocation glide and dislocation creep, and the metamorphic P- T conditions of theductile shear system are T=...