Petrography and geochemistry of proterozoic clastic sedimentary rocks of dhumwad, northern karnataka: weathering history, provenance and tectonic setting implications Sukhaye Raju1, Manjunatha S.1,* 1Department of Geology, Karnatak Science College, Dharwad, Karnataka, India *E-mail: manjunathas29@yahoo.in
Online published on 22 May, 2019. Abstract The petrography and geochemical (major, trace and rare earth elements) studies of Proterozoic clastic sedimentary rocks of Dhumwad region, which resemble the Kaladgi Group, and are unconformably separated by the Eparchaean Unconformity, occur over Archaean gneisses and schistose formations at Dhumwad, Northern Karnataka. The study area is mainly composed of sandstones, grit and conglomerate. The present petrographic studies of different samples from the Dhumwad section reveal that they are sub-mature to mature in nature. Geochemistry of the clastic sedimentary rocks of Dhumwad area reflects high SiO2 content followed by low Fe2O3 and MgO. The REE pattern of the rock samples shows LREE enrichment and the relatively flat nature of HREE with negative Eu anomalies. Al2O3/TiO2 ratio of these samples varies from 22.53–89.40 with an average of 51.49, which suggests that the samples from the study area were derived from felsic igneous rocks. Furthermore, a felsic origin is supported by the elemental ratios of Eu/Eu*, (La/Lu)CN, La/Sc, Th/Sc, Th/Co, Cr/Th, La/Ca. It is seen from A-CN-K diagram and CIA values, which range from 74.33 to 82.76 with an average of 78.41, that the source material of these rock samples had undergone moderate to high degree of chemical weathering. Geochemical discrimination diagrams for these clastic sedimenatry rocks from the Dhumwad study area reflect their deposition in a passive margin tectonic setting. Top Keywords Provenance, Weathering History, Tectonic Setting, Geochemistry, Clastic Sedimentary Rocks, Dhumwad. Top |