Superimposed Folding in the Transitional Rocks (Precambrians) and its Influence on the Structure of South Eastern Margin of the Vindryan Basin, Jabalpur District, Madhya Pradesh

Abstract The author outlines the general geologic setting of the Transitional rocks (Precambrians) of the Jabalpur district, describes the principal characteristics of folding, records the divergence in orientation, and suggests an explanation for the regional tectonic setting. The folds occur in a thick sequence of sub-metamorphic rocks which have been subjected to repeated folding. Two successive phases of folding have been recognised; major folds of the first phase account for the over all structural pattern shown by the lithologic units; while the second phase occurs mostly as minor folds. The major folds are isoclinal to overturned folds and their axial planes and fold limbs strike north-east and dip steeply, the fold axes plunge steeply towards NE. The general strike of the axes and axial planes of the later phase is north-west, plunging SE. Along the south-eastern margin of the Vindhyan basin where it abuts against these repeatedly deformed rocks, a flat elongated dome has been developed around labera and Katangi. Regarding the mode of formation of the dome structure, it is suggested that it has resulted from the interference of two sets of folding in the basement rocks and the subsequent tectonic movement direction lay close to the axial plane of the second fold set.