Stratigraphy and Structure of the Sandur Schist Belt, Karnataka

Sandur schist belt comprises predominantly of volcanic rocks with subordinate amount of metasediments. Mineralogy of the clastic sediments indicates a pre-existing sialic crust. The schist belt represents a fracture-controlled basin having an unstable tectonic set-up. Two distinct phases of folding deformation (SD₁ and SD₂), of which the earlier one (SD₁) is quite pronounced producing the NW-SE trending regional structure of the schist belt, are noted. SD₁ is associated with the development of macroscopic folds (F₁), tight to isoclinal mesoscopic folds (f₁ ), schistosity (S₁ ), mineral lineation I_m), fold mullion (I_n), and pebble lineation (I_p). SD₂ is associated with the development of broad warps (F₂) with axial traces along ENE-WSW direction, open to close mesoscopic folds (f₂) and crenulation cleavage (S₂).