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Strain-partitioned dextral transpression in the Great Boundary Fault Zone around Chittaurgarh, NW Indian Shield
Geological Magazine ( IF 2.3 ) Pub Date : 2021-03-22 , DOI: 10.1017/s0016756821000157
Deepak C. Srivastava , Ajanta Goswami , Amit Sahay

Delimiting the Aravalli mountain range in the east, the Great Boundary Fault (GBF) occurs as a crustal-scale tectonic lineament in the NW Indian Shield. The structural and tectonic characteristics of the GBF are, as yet, not well-understood. We attempt to fill this gap by using a combination of satellite image processing, high-resolution outcrop mapping and structural analysis around Chittaurgarh. The study area exposes the core and damage zone of the GBF. Three successive phases of folding, F1, F2 and F3, are associated with deformation in the GBF. The large-scale structural characteristics of the GBF core are: (i) a non-coaxial refolding of F1 folds by F2 folds; and (ii) the parallelism between the GBF and F2 axial traces. In addition, numerous metre-scale ductile shear zones cut through the rocks in the GBF core. The damage zone is characterized by the large-scale F1 folds and the mesoscopic-scale strike-slip faults, thrusts and brittle-ductile shear zones. Several lines of evidence, such as the inconsistent overprinting relationship between the strike-slip faults and thrusts, the occurrence of en échelon folds and the palaeostress directions suggest that the GBF is a dextral transpression fault zone. Structural geometry and kinematic indicators imply a wrench- and contraction-dominated deformation in the core and damage zone, respectively. We infer that the GBF is a strain-partitioned dextral transpression zone.

中文翻译:

西北印度地盾 Chittaurgarh 周围大边界断层带的应变分区右旋挤压

大边界断层(GBF)在东部划定阿拉瓦利山脉的界线,是西北印度盾的地壳尺度构造线。迄今为止,GBF 的构造和构造特征还不是很清楚。我们试图通过结合使用卫星图像处理、高分辨率露头测绘和 Chittaurgarh 周围的结构分析来填补这一空白。研究区暴露了 GBF 的核心区和破坏区。三个连续的折叠阶段,F1,F2F3, 与 GBF 中的变形有关。GBF核心的大规模结构特征是:(i)非同轴重折叠F1折叠F2折叠; (ii) GBF 和F2轴向痕迹。此外,许多米尺度的韧性剪切带穿过 GBF 核心中的岩石。破坏区的特点是规模大F1褶皱和细观尺度走滑断层、逆冲断层和脆韧性剪切带。走滑断层与逆冲断层叠印关系不一致、梯形褶皱的出现、古应力方向等多方面的证据表明,GBF为右旋压断带。结构几何和运动学指标分别意味着核心区和损伤区的扳手和收缩主导的变形。我们推断 GBF 是一个应变分隔的右旋挤压带。
更新日期:2021-03-22
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