Structure of the Type Charnockite Area Near Madras

In the type area of the charnockites, south of the city of Madras, foliation attitudes of marker horizons of leptynites and of basic granulite bands trace a map pattern characterized by four-fold hinges. The overall structure of the area is brought out by the swerve of axial planes of these folds from NNE in south-west through E-W in the central part to N-S in southern part in a broad sweep. The folding is noncylindrical; and a probable structural interpretation, as advanced here, envisages a series of tight isoclinal folds on which a folding around a N-S axial plane has been superposed.