摘要
变形构造研究显示阿尔金断裂带东段可划分成具有近水平拉伸线理的韧性左行走滑变形域(SS)和具有陡角度倾伏拉伸线理的收缩变形域(PS)。在SS与PS之间的过渡区域还发现中等角度倾伏的拉伸线理。在SS区域内,大量的标志显示剪切作用为左旋走滑,在垂向剖面露头上可看到一些纯剪现象;而在PS变形域,则以垂向上的纯剪应变(垂向拉伸)为主,在水平露头上局部显示出左旋剪切特征。这些现象说明SS变形域以水平方向的简单剪切为主,具有少量垂向上的纯剪应变分量;而PS变形域则以纯剪应变为主,具有少量的水平简单剪切分量。因此,阿尔金东段可看作为一个转换挤压变形带,它可能为塔里木地块与柴达木地块斜向会聚作用的产物。在其韧性变形过程中,被分解成以左行走滑为主的变形域和以水平缩短、垂向拉伸为主的变形域,前者造成平行阿尔金走向的侧向运动,后者则引起阿尔金构造带的缩短、地壳加厚和山体隆升。
Studies of deformation structure in the eastern segment of the Altun fault zone indicate that it can be divided into the ductile sinistral strike-slip domain with subhorizontal stretching lineations (SS domain) and the contractional deformation domain with steeply plunging stretching lineations (PS). Moderate-angle plunging stretching lineations can been also found locally between the SS domain and PS domain. In the SS domain lots of shear sense indicators show sinistral strike-slip, features, and pure shear strain indicators are seen locally in outcrops perpendicular to foliations. However,in the PS domain lots of pure shear strain indicators are found in outcrops perpendicular to foliations , and sinistral shear indicators can been seen locally in subhorizontal outcrops. The phenomena show that in the SS domain horizontal simple shear is dominant with some pure shear strain, but in the PS domain pure shear strain is dominant with some horizontal simple shear. Therefore, The eastern segment of the Altun fault zone may be considered as a transpressional deformation zone which resulted from oblique convergence between the Tarim block and Qaidam block. During the ductile transpressional deformation, the deformation was partitioned into the dominantly sinistral strike-slip domain and the dominantly horizontal shortening and vertical stretching domains. The former brough about lateral movement paralled to the strike of the Altun fault zone, while the latter resulted in shortening of the Altun zone, crustal thickening and mountain uplift.
出处
《地质论评》
CAS
CSCD
北大核心
1998年第4期348-356,共9页
Geological Review
基金
国家305项目(编号06-04专题)及中法"阿尔金山-祁连山构造演化及岩石圈剪切作用"合作项目成果
关键词
断层
转换挤压带
变形分解作用
阿尔金断裂带
ductile sinistral strike-slip deformation domain
contractional deformation domain
transpressional zone
deformation partition
Altun fracture zone
