Petrography and Clay Mineralogy of Intertrappean Beds of Mumbai, India

Petrographic attributes of intertrappean beds exposed at four localities in Mumbai, one each at Malabar and Worli Hills and two at the Amboli quarry, Jogeshwari are studied in detail. Microfacies of vitric tuff, lithic tuff and black carbonaceous shale have been identified, which differ from their counterparts in other intertrappean localities of peninsular India in having a significant amount of pyroclastics. Bulk XRD anatyses of intertrappean beds of Malabar Hill show similar mineral assemblage in tuffs as well as black carbonaceous shales pointing towards the same provenance for these beds. Further, the XRD analysis of the clay fraction of these samples reaffirms their pyroclastic nature, the pyroclasts being reworked in most cases.