The objective of this study is to evaluate progressive variation in the state of stress at ca 2.5 Ga in Hutti region of Eastern Dharwar Craton (EDC, southern India). Paleostress analysis is performed using quartz vein orientations in metavolcanic and granitoid rocks (ca 2.5 Ga) of the region. It is established that veins in the metavolcanic rocks formed during regional D3 deformation under N–S compression that is related to N–S directed far-field stress, which is also responsible for D3 folds with E-W striking axial planes in parts of the EDC. Anisotropy of magnetic susceptibility data from the granitoids yields NNW-SSE striking fabric anisotropy that developed during regional D1/D2 deformation. Paleostress analysis using veins in the granitoids of the region yields NE-SW compression. However, the kinematics of formation of these veins is shown to be compatible with dextral simple shear along pre-existing NNW-SSE oriented fabric under N–S directed D3 compression. Therefore, it is established that veins in the metavolcanic and granitiod rocks of the study area formed under the same N–S directed D3 far-field stress, an interpretation that is further supported by the similar values of stress ratio obtained from 3D Mohr circle analysis of vein data from the two lithologies. Thus, the study demonstrates that there are pitfalls in direct evaluation of paleostress using only vein orientations and that understanding kinematics of vein emplacement is critical in paleostress analysis. Our data further reveal that the granitoids were subjected to faulting during the final stages of D3 due to which the veins are displaced. Paleostress analysis using fault-slip data from the granitoids yields NNE-SSW compression. This local variation of paleostress in granitoids is due to late-D3 brittle deformation during cratonization of the Dharwar Craton at ca 2.5 Ga.

这项研究的目的是评估东部Dharwar Craton（EDC，印度南部）的Hutti地区约2.5 Ga处应力状态的逐步变化。使用该区域的超火山岩和花岗岩岩（ca 2.5 Ga）中的石英脉方位进行古应力分析。可以确定，在区域D3变形下，在N–S压缩下形成的中火山岩中的脉与N–S定向的远场应力有关，这也导致EW撞击EDC部分轴向平面时D3褶皱。来自花岗岩的磁化率数据的各向异性产生了在区域D1 / D2变形期间形成的NNW-SSE打击织物各向异性。使用该区域的花岗岩中的静脉进行古应力分析会产生NE-SW压缩。然而，这些脉线的运动学研究表明，在N–S方向D3压缩下，沿先前存在的NNW-SSE定向织物的右旋简单剪切是兼容的。因此，可以确定在相同的N-S定向D3远场应力作用下，研究区的准火山岩和花岗石岩石中的脉状形成，这一解释进一步得到了3D Mohr圆分析获得的相似应力比值的支持。来自两种岩性的静脉数据。因此，该研究表明仅使用静脉方向直接评估古应力是有缺陷的，了解静脉位置的运动学对古应力分析至关重要。我们的数据进一步揭示，在D3的最后阶段，由于类固醇脉被置换，花岗岩遭受断层作用。使用来自花岗岩的断层滑动数据的古应力分析产生NNE-SSW压缩。花岗岩中古应力的这种局部变化是由于Dharwar Craton在约2.5 Ga的克拉通化过程中后期D3的脆性变形引起的。