SUPERPOSED FOLDING IN THE HONAKERE ARM OF THE CHITRADURGA-KARIGHATTA SCHIST BELT IN THE DHARWAR TECTONIC PROVINCE, SOUTHERN INDIA, AND ITS BEARING ON THE SARGUR-DHARWAR RELATION

The supracrustal enclave within the Peninsular Gneiss in the Honakere arm of the Chitradurga-Karighatta belt comprises tremolite-chlorite sc hists within which occur two bands of quartzite coalescing east of Jak kanahalli (12 degrees 39'N; 76 degrees 41'E), with an amphibolite band in the core. Very tight to isoclinal mesoscopic folds on compositiona l bands cut across in the hinge zones by an axial planar schistosity, and the nearly orthogonal relation between compositional bands and thi s schistosity at the termination of the tremolite-chlorite schist band near Javanahalli, points to the presence of a hinge of a large-scale, isoclinal early fold (F-1). That the map pattern, with an NNE-plungin g upright antiform and a complementary synform of macroscopic scale, t races folds of a later generation (F-2), is proved by the varying atti tude of both compositional bands (S-0) and axial planar schistosity (S -1), which are effectively parallel in a major part of the area A cren ulation cleavage (S-2) has developed parallel to the axial planes of t he F-2 folds at places. The F-2 folds range usually from open to rarel y isoclinal style, with the F-1 and F-2 axes nearly parallel. Evidence of type 3 fold interference is also provided by the map pattern of a quartzite band in the Borikoppalu area to the north, coupled with youn ging directions from current bedding and S-0 - S-1 inter-relation. Alt hough statistically the F-1 and F-2 linear structures have the same or ientation, detailed studies of outcrops and hand specimens indicate th at the two may make as high an angle as 90 degrees. Usually, in these instances, the F-1 lineations are unrollable around the F-2 axes, impl ying that the F-2 folding was by flexural slip. In zones with very tig ht to almost isoclinal F-2 folding however, buckling attendant with fl attening has caused a spread of the F-1 lineations almost in a plane. Initial divergence in orientation of the F-1 lineations due to extreme flattening during F-1 folding has also resulted in a variation in the angle between the F-1 and F-2 lineations in some instances. Upright l ater folding (F-3) with nearly E-W strike of axial planes has led to w arps on schistosity, plunge reversals of the F-1 and F-2 axes, and inc rease in the angle between the F-1 and F-2 lineations at some places. Large-scale mapping in the Borikoppalu sector, where the supposed Sarg ur rocks with ENE 'trend' abut against the N-'trending' rocks of the D harwar Supergroup, shows a continuity of rock formations and structure s across the hinge of a large-scale F-2 fold. This observation renders the notion, that there is an angular unconformity here between the ro cks of the Sargur Group and the Dharwar Supergroup, untenable.