Geochemistry of Late Eocene/Oligocene calcretes (caliche) of the Northwestern Himalaya, India

Late Eocene/Oligocene calcretes of the northwestern Himalaya were studied for their geochemical behaviour. Bulk chemical composition of these calcretes shows SiO2 Al2O3, and CaO as their major contituents. The laminar calcretes show higher percentage of CaO as compared to nodular and powdery varieties. Low percentage of CaO (<4.0%) in powdery calcrete samples may be because of poor accumulation of carbonate in them. The MgO and other minor oxides occur in low concentrations in them. The low concentration of the MgO suggests that carbonate phase is mainly calcite. The Al2O3 accounts for clay content in the calcretes and Pep, comes from iron minerals, which are the essential constituents of the host mudstones. The Sr and Ba occur in appreciable amounts but they do not follow a definite trend with respect to Ca. Other trace elements such as Cu, Cr, Co and Ni occur in small concentrations and either they have replaced Ca in calcite or they occur as a part of their own minerals.