STRUCTURAL ARCHITECTURE OF THE VINDHYAN STRATA IN SON VALLEY - IMPLICATIONS FOR BASIN TECTONICS

Detailed field studies on the regional structure of the Vindhyan strat a in Son valley reveal that the Vindhyan strata define a broad synclin e with a gently plunging (westerly), mildly curved fold axis (average trend ENE-WSW) and a southerly inclined axial plane. The southern limb of the broad syncline shows several smaller folds which are conspicuo usly absent in the gently dipping, homoclinal, northern limb. The meso scopic folds also conform to the regional structural pattern. Progress ive deformation of horizontal strata under asymmetric compression asso ciated with a vertical shear displacement has been simulated with the help of a computer software. The computer-generated structural pattern is remarkably similar to the pattern revealed from field studies indi cating that the structural pattern of the Vindhyan strata is the conse quence of asymmetric compression with the northerly directed force far exceeding the magnitude of the southerly directed force. Absence of a ny northerly directed compressional movement in the Indian peninsula i n post-Vindhyan period suggests that the deformation of the Vindhyan h ad been syn-Vindhyan, perhaps associated with the Satpura orogeny. Thi s leads to the deduction that the origin and evolution of the Vindhyan basin was related to flexural subsidence:associated with repeated thr ust loading in the south.