Age of granitic activity associated with copper?molybdenum mineralization at Malanjkhand, Central India

Abstract

The Malanjkhand copper–molybdenum deposit in the Bhandara Craton, Central India, is hosted by a granite complex which consists of regionally dominant “grey granitoid” and “pink granitoid” confined to the mineralized zone. New SHRIMP RG data on zircons from both granite types are inferred to have crystallized during the same magmatic pulse at ca 2.48 Ga. The discrepancy between zircon age and earlier obtained Rb–Sr whole-rock age is attributed to modification of the Rb–Sr system by hydrothermal overprint. Similarity in petrographic features and chemical affinity in combination with identical age strongly indicate that the pink granite is the hydrothermally altered variety (microclinization and silicification) of the grey granite. The spatially associated, main Cu–Mo mineralization event at Malankhand appears to be broadly contemporaneous with and genetically related to the emplacement of the host granitoids at about 2.48 Ga.