Implications of new 40Ar/39Ar age of Mallapur Intrusives on the chronology and evolution of the Kaladgi Basin, Dharwar Craton, India

The Kaladgi Basin on the northern edge of the Dharwar craton has characters diverse from the other epicratonic Purana basins of Peninsular India. Sedimentological studies in the basin have established the presence of three cycles of flooding separated by an event of intra-basinal deformation accompanied by low grade incipient metamorphism. The overall structural configuration of the basin indicates its development by supracrustal extension accompanied by shearing in a trans-tensional regime during the Mesoproterozoic. This was followed by sagging that yielded Neoproterozoic sedimentation in a successor nested basin. 40 Ar/ 39 Ar dating of an intrusive mafic dyke along the axial plane of a fold has yielded a plateau age of 1154 ± 4 Ma . This helps constraint the age of the various events during the evolution of this basin.