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。
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= 630~680℃ and P= 0. 67GPa, respectively. The average strainvalue is 4. 47 , and the differential strain is 44. 57~ 79. 5MPa. This system was formed inthe extention and rifting stage of the early Mesoproterozoic orogenic evolution.② Contraction compressional ductile shear system: The deforrnation mechanism isfeatured mainly of intergranular gliding, and of intracystalline dislocation creep, and themetamorphic P-T Condition of this ductile shear system are T= 600~ 700℃, P= 0. 77~0. 85GPa, respectively. The shear strain value varies between 1. 2 and 2. 1, and thedifferential strain is 62. 22 MPa. This system was formed in the compression - upliftingorogenic stage of the early - middle Neoproterozoic period.③Thrusting - napping ductile shear system: the deformation mechanism is featuredmainly by dislocation gliding and dislocation creep,with intergranular gliding as well,and themetamorphic P-T Conditions are T = 514 ℃ and P = 0. 77GPa, respectively. The shearstrain value varies between 3 and 5, and the differential strain varies between 69. 96 and 86.75MPa. This system was forrned in the thrusting - nappe orogeny of the middle stage ofNeoproterozoic period.
出处
《山东地质》
1997年第2期10-18,共9页
Geology of Shandong
