Abstract
Abstract The medium‐ to coarse‐grained and porphyritic granitoid of Dharmawaram, Karimnagar district, Andhra Pradesh, south India is a biotite‐hornblende granite with notable contents of rare metal (Zr, Hf, Th) and rare earth (including Y) minerals like zircon, thorite, allanite, monazite and xenotime. Chemically, it is metaluminous (average A/C+N+K = 0.95)‐type, potassic (av. 5% K2O) granite, with dominantly sub‐alkaline characters. It shows up to 8 times enrichment of rare metals (Zr, Hf, U, Th) and rare earths (including Y, Sc), with reference to their abundances in normal unevolved granite, and hence, fertile for some of these elements. Field, petrological, geochemical and isotopic data of potassic granite (PG) indicate involvement of silica‐rich metasedimentary‐basic crustal rocks (amphibole‐quartzite, amphibolite, hornblende‐biotite gneiss, etc.) in its genesis, at a depth range of 30 km. Further, chondrite‐normalized REE patterns demonstrate that low‐degree partial melting of source rocks is the major controlling factor in the genesis of PG. Mild negative Eu‐anomaly (av. Eu/Eu* = 0.48), plots of Ba‐Rb‐Sr in the field of anomalous granite and K/Rb ratios (av. 239) in the range that is shown by normal unevolved granite together indicate less fractionated nature of the PG. Limited fractionation of metalumination‐type, involving hornblende, led to occasional weak alumina saturation. Interestingly, geochemical and petrogenetic features of the studied PG broadly match with those potassic granites which are already known to host anomalously high enrichment of rare metals and rare earths in other parts of Andhra Pradesh and adjoining Karnataka.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.