Application of Geochemical Mapping in Unraveling Paleoweathering and Provenance of Karewa Deposits of South Kashmir, NW Himalaya, India

Abstract

Ninety Six composite stream sediment samples of Karewa deposits from parts of Pulwama and Budgam districts of south Kashmir were analysed for major, trace and rare earth elements to understand the nature of weathering and provenance. A-CN-K and A-CNK-FM plots of the samples indicate almost similar contents in Al2O3, CaO, Na2O, K2O and MgO as those of upper crust, reflecting very poor to moderate weathering history. Similarly, the low to moderate chemical index of alteration (CIA) values (33.97 to 68.87), chemical index of weathering (CIW) values (57.68 to 84.80) and plagioclase index of weathering (PIA) values (31.49 to 75.67) suggest a low to moderate intensity of weathering in source area. The discriminant function diagrams revealed quartzose sedimentary provenance, with some of the samples falling in intermediate igneous source, probably reflecting recycled orogen provenance. The sample data show fractionated REE patterns with (La/Yb)cn varying from 7.42 to 9.52 and a negative Eu anomaly 0.64–0.71, is regarded as evidence for a differentiated source. In La–Th–Sc diagram, sediments fall in a region of mixed source rocks with two samples falling in basic source rock area. The samples fall close to the values of UCC, PAAS and NASC, indicating large provenance with variable geographical and geological setting. On La/Th plot, the sediment data fall into the range of UCC, indicating that the sediments did not have a uniform provenance.