Intracontinental thrusts and inclined transpressio

Authors: Dilip Saha S Chakraborti V Tripathy

Publish Date: 2010/02/16

Volume: 75, Issue: 1, Pages: 323-337

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Abstract

Recent works suggest Proterozoic plate convergence along the southeastern margin of India which led to amalgamation of the high grade Eastern Ghats belt EGB and adjoining foldandthrust belts to the East Dhrawar craton Two major thrusts namely the Vellikonda thrust at the western margin of the Nellore Schist belt NSB and the Maidukuru thrust at the western margin of the Nallamalai fold belt NFB accommodate significant upper crustal shortening which is indicated by juxtaposition of geological terranes with distinct tectonostratigraphy varying deformation intensity structural styles and metamorphic grade Kinematic analysis of structures and fabric of the fault zone rocks in these intracontinental thrust zones and the hanging wall and footwall rocks suggest spatially heterogeneous partitioning of strain into various combinations of EW shortening toptowest shear on stratum parallel subhorizontal detachments or on easterly dipping thrusts and a strike slip component Although relatively less prominent than the other two components of the strain triangle nonorthogonal slickenfibres associated with flexural slip folds and mylonitic foliationstretching lineation orientation geometry within the arcuate NSB and NFB indicate left lateral strike slip subparallel to the overall NS trend On the whole an inclined transpression is inferred to have controlled the spatially heterogeneous development of thrust related fabric in the terrane between the Eastern Ghats belt south of the Godavari graben and the East Dharwar craton

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