Geology and Geochemistry of Granites Around Jaswantpura, Jalore District, Southwestern Rajasthan, India

The Neoproterozoic granite plutons around Jaswantpura, western India, form a large complex of granitic rocks and, at least, four distinct granite types, based on cross-cutting relationships, have been found: coarse- to medium-grained biotite granites; medium- to fine-grained two- mica granites; coarse- to medium-grained porphyritic hornblende granites and fine-grained biotite granites with accessory hornblende. Younger acidic and basic dykes cut these granites. The Jaswantpura granites show a narrow range of variation in terms of their chemistry. The hornblende granites are hypersolvus with mild peralkaline character as reflected by the enrichment in incompatible trace elements including Zr, Nb, La and REE but are characterized by relatively low Sr and Al2O3. The biotite granites are subsolvus, mildly to moderately peraluminous and are characterized by relatively high SiO2, Al2O3, Rb and low Zr, Nb and REE contents compared to the hornblende granites. The mineralogical and chemical characteristics of the different granite types exposed in the Jaswantpura area point to a continental crust source.