Geochemistry of Karewa deposits of NW Himalaya: implications on provenance and tectonic setting.

The objective of the work is to understand the provenance and tectonic setting of the Karewa deposits of South Kashmir, NW Himalayas using major, trace and rare earth elements. Major elemental analysis shows that sediments are rich in SiO₂ followed by Al₂O₃, Fe₂O₃, CaO, MgO, K₂O, Na₂O, P₂O₅, TiO₂ and MnO. The geochemical classification diagram of Heron and Pettijohn suggested that the sediments were classified as lith-arenites, trending toward wackes, which suggested the immaturity of the sediments. The SiO₂/Al₂O₃ ratio of 3.99 to 4.9 and Al₂O₃/TiO₂ ratio of 12.2 to 18.7 reflected that the Karewa sediments were derived largely from intermediate and felsic sources. On V-Ni-(Th*10) ternary plot, the samples fall near the felsic source with an extension towards the mafic source rock field. Moreover, the fractionated chondrite normalized rare earth element patterns with enriched light rare earth elements (LREE) and nearly flat heavy rare earth elements (HREE) and negative europium anomalies (0.59 to 0.74) suggested that these rocks were derived from felsic to intermediate rocks of the upper continental crust with some contamination by a mafic component. The Th/Sc and Zr/Sc plot of the sediments suggest both compositional variation and new addition of Zr in the sedimentary system. Using high and low silica multidimensional discrimination diagrams and single axis discrimination plot, the source rocks of Karewa deposits show affinity towards passive margin and collision—arc tectonic settings. The ratios of Cu/Zn, U/Th and Ni/Co indicate that the Karewa sediments were deposited in oxidizing environmental conditions. [ABSTRACT FROM AUTHOR]