Abstract
Large (up to 3 m), xenolith-like boulders of dioritic gabbros are found in the Deccan basalts near Shahada and Shirpur in northern Maharashtra, along ENE–WSW-trending structural ridges. Both these dioritic gabbros have been dated by the 40Ar-39Ar incremental heating technique, and have yielded typical Deccan ages of ~ 66 Ma. These ages rule out the possibility of these rocks representing the basement crust of the area. The rocks from both ridges are petrographically, chemically and isotopically similar. In addition, their Sr–Nd–Pb isotopic ratios indicate that they are isotopically identical with some of the Mahabaleshwar Formation lavas of the Western Ghats Deccan. However, these rocks are more evolved chemically compared to typical Mahabaleshwar Formation lavas. These characteristics suggest that they are the likely products of fractional crystallization of a parental Mahabaleshwar-like magma generated in this region.