Quantitative Analysis of Finite Strain Accumulation and its Variation Across the Fold System in Southern Kaladgi Basin Around Bagalkot, India

Deformative forces exert stress on rock formations, when sufficient, these forces turn penetrative, correspondingly causing the rocks to accommodate strain. Numerous strain measurement techniques (Finite strain analysis) have been documented by early pioneers in kinematics, among which R_f/ϕ method is utilized in the current investigation of the southern region of the Proterozoic Kaladgi basin near Bagalkot. The Kaladgis show significant structural disturbance (joints, faults, and shears), making them suitable for Kinematic Study. This study focuses on measurement of the strain across the doubly plunging fold, which includes both anticline and syncline in a fold system. Oriented samples were used for thin sections. Meticulously procured Optical photomicrographs of these samples were analysed using the R_f/ϕ approach in Ellipse Fit V3.11.0 software with designated tools and methods. The samples exhibit a strain range of R_s 1.16 to 1.99 for XZ sections and, ε_s (Strain amount) 0.099 to 0.427 which accounts the amount of force acting on a plane at an angle. In Flinn and Logarithmic diagrams to visualise data, all samples fall within the apparent flattening field, indicating compressional forces exerted on a spherical body resulted in a flattened oblate ellipsoid geometry (σ1 = σ2>>σ3) indicative of compressional tectonic and progressive deformation. These are defined by the Flinn parameter (k) and d value, a potential measure of strain intensity, (0.1189 to 0.6242) whose variation proves strain localisation defined by higher ellipticity of grains.