Magmatic uraniferous albitite bodies around Geratiyon ki Dhani, Sikar district, Rajasthan, India

A number of uraniferous albitite occurrences have been reported in Rajasthan associated with Archaean basement and Meso-proterozoic rocks of Delhi Supergroup. Albitite bodies in Geratiyon ki Dhani are located along NE-SW trending eastern albitite zone in Khetri sub-basin of North Delhi Fold Belt. The albitite occurs as a NNW -SSE trending linear ridge extending over 1.5 km strike length intruding metasediments of Ajabgarh Group represented by quartzite, quartz-biotite schist and calc-silicate rock. The magmatic origin of albitite is characterised by sharp (intrusive) contact of albitite with metasediments, xenoliths of quartz-biotite schist and presence of igneous textures and absence of replacement textures in albitite. Subsurface exploration in the area has established uranium mineralization over 1200 m strike length and 300 m vertical depth, occurring as steeply dipping low grade lodes with varying thickness. The uraniferous albitites are dominantly pink to red coloured fine- grained rocks, composed of albite (85-90%), quartz (5-10%), K-feldspar (1-2%), minor biotite «1 %) and secondary chlorite and calcite. Davidite is the most abundant radioactive phase with minor brannerite and U-Ti complex. REE mineral assemblages such as monazite, xenotime, bastnaesite and zircon were identified. Geochemical studies of the uraniferous albitite recorded high Na₂O (av. 9.67 %) and low K₂O (av. 0.40 %) content. Albitites are enriched in REE (av. 1249 ppm), especially LREE (av. 1143 ppm) leading to high LREE/HREE ratio (av. 12.27). Recognition of uraniferous albitites with distinct magmatic characteristics around Geratiyon ki Dhani has enhanced the uranium potentiality of eastern albitite zone and has strengthened the scope of exploration activities in the adjacent ares. (author)