Abstract The E-W striking Kachchh Rift Basin (KRB) at the western continental margin of Indian plate is located in the northern part of Gujarat state, India. KRB has undergone polyphase deformation owing to changing stress-field since Late Triassic. We establish the kinematic framework along the NW striking intra-uplift Vigodi-Gugriana-Khirasra-Netra Fault System (VGKNFS) located at the western part of the KRB. The VGKNFS consists of 0.25–50 km long, sub-parallel, striated, reactivated dip-slip faults. A total of 1150 fault-slip data consisting of fault plane and striations attitude were recorded from 66 sites (including a single site with systematic joints). Slip-sense of faults was determined by documenting kinematic indicators. Paleostress analysis was carried out using Win-Tensor, T-Tecto, FaultKin and SG2PS to compare and validate the results. The chi-square statistical analysis was undertaken to evaluate how relevant are paleostress analysis results to the present-day compressional stress field. Geophysical investigations were conducted at selected sites using Ground Penetrating Radar (GPR) to understand the shallow subsurface geometry and trace the continuity of faults buried below patchy alluvial cover. 15–17 m long, 2D GPR cross-sections were recorded across faults using monostatic antenna of 200 MHz frequency. Two major deformation events – D1 and D2 are determined in the present study. The extension event D1 shows W and NW-NNW extension during Late Triassic to Late Cretaceous. It occurred during the rift phase of KRB in response of the break-up of Gondwanaland. The latest event D2 shows NNE-NE compression from Late Cretaceous up to the present. It is interpreted to have developed during post-rift inversion phase, induced by collision of the Indian plate with the Eurasian plate at ∼55 Ma.

中文翻译：

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印度地震活跃的 Kachchh 裂谷盆地内隆起内 Vigodi-Gugriana-Khirasra-Netra 断层系统的构造演化：对印度板块西部大陆边缘的影响

摘要 位于印度板块西部大陆边缘的东西向克奇裂谷盆地（KRB）位于印度古吉拉特邦北部。由于晚三叠世以来应力场的变化，KRB 经历了多相变形。我们沿着位于 KRB 西部的 NW 显着的隆起内 Vigodi-Gugriana-Khirasra-Netra 断层系统 (VGKNFS) 建立了运动学框架。VGKNFS 由 0.25-50 公里长的、次平行的、条纹的、重新激活的倾滑断层组成。从66个站点（包括具有系统节理的单个站点）共记录了1150个由断层面和条纹姿态组成的断层滑动数据。通过记录运动学指标来确定故障的滑动感。使用 Win-Tensor、T-Tecto、FaultKin 和 SG2PS 进行古应力分析，以比较和验证结果。进行卡方统计分析以评估古应力分析结果与当今压缩应力场的相关性。使用探地雷达 (GPR) 在选定地点进行了地球物理调查，以了解浅层地下几何形状并追踪埋在斑驳冲积层之下的断层的连续性。使用 200 MHz 频率的单基地天线在断层上记录了 15-17 m 长的 2D GPR 横截面。本研究确定了两个主要的变形事件——D1 和 D2。伸展事件 D1 显示了晚三叠世至晚白垩世的 W 和 NW-NNW 伸展。它发生在 KRB 的裂谷阶段，以响应冈瓦纳大陆的分裂。最新事件 D2 显示了从晚白垩世到现在的 NNE-NE 压缩。