Abstract We present new fault slip data to decipher the tectonic stress regime in younger granites (2.61 Ga) of western Dharwar craton (WDC), south India. The study is based on paleostress reconstruction of the terrain using fault-slip data from the small scale oblique slip normal faults of Chitradurga granite. Paleostress analysis using Right Dihedron and Rotational Optimization methods reveal that these faults have developed under NNE-SSW directed extension. Similar results are also obtained when left-lateral and right-lateral oblique-slip normal faults are treated as separate entities. It is envisaged that all faults in Chitradurga granite have developed under a single tectonic event and are considered to be extensional shear fractures. We interpret that the oblique-slip normal faults in granite oriented along NNW-SSE to N-S (P shear), NW-SE (R shear), NE-SW (R′ shear), and WNW-ESE (T) are defined as the respective shear components of the regional riedel shear system. It developed due to sinistral movement along the Chitradurga Shear Zone (CSZ) during late D3 deformation at shallow crustal level. The fault planes act as primary or secondary shear planes, depending on their proximity to the CSZ and kinematically fit well with regional far-field compression. The present study addresses the formation of oblique slip normal faults in the Chitradurga granite and its implication in reconstructing the paleostress field in the Precambrian south Indian shield.

中文翻译：

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印度南部达尔瓦尔克拉通西部古应力场重建：来自年轻花岗岩脆性断层和相关结构的证据

摘要 我们提出了新的断层滑动数据来破译印度南部西达尔瓦尔克拉通 (WDC) 的年轻花岗岩 (2.61 Ga) 的构造应力状态。该研究基于使用 Chitradurga 花岗岩小规模斜滑动正断层的断层滑动数据对地形进行古应力重建。使用右二面体和旋转优化方法进行的古应力分析表明，这些断层是在 NNE-SSW 定向伸展下发育的。当将左侧和右侧斜滑正断层作为单独的实体处理时，也获得了类似的结果。预计 Chitradurga 花岗岩中的所有断层都是在单一构造事件下发育的，被认为是拉伸剪切断裂。我们解释为花岗岩中的斜滑正断层沿 NNW-SSE 到 NS（P 剪切）取向，NW-SE (R 剪切)、NE-SW (R' 剪切) 和 WNW-ESE (T) 被定义为区域里德尔剪切系统的各自剪切分量。它是由于在浅地壳水平的 D3 晚期变形期间沿 Chitradurga 剪切带 (CSZ) 的左旋运动而发展起来的。断层面作为主要或次要剪切面，取决于它们与 CSZ 的接近程度，并且在运动学上与区域远场压缩很好地吻合。本研究探讨了 Chitradurga 花岗岩中斜滑动正断层的形成及其对重建前寒武纪南印度地盾古应力场的意义。它是由于在浅地壳水平的 D3 晚期变形期间沿 Chitradurga 剪切带 (CSZ) 的左旋运动而发展起来的。断层面作为主要或次要剪切面，取决于它们与 CSZ 的接近程度，并且在运动学上与区域远场压缩很好地吻合。本研究探讨了 Chitradurga 花岗岩中斜滑动正断层的形成及其对重建前寒武纪南印度地盾古应力场的意义。它是由于在浅地壳水平的 D3 晚期变形期间沿 Chitradurga 剪切带 (CSZ) 的左旋运动而发展起来的。断层面作为主要或次要剪切面，取决于它们与 CSZ 的接近程度，并且在运动学上与区域远场压缩很好地吻合。本研究探讨了 Chitradurga 花岗岩中斜滑动正断层的形成及其对重建前寒武纪南印度地盾古应力场的意义。