A STUDY OF APATITE MAGNETITE ROCKS

Abstract

The Purulia apatite-magnette body occurs along the South Purulia Shear Zone (SPSZ) or Northern Sheai. /one (NSZ). The study area is in Beldih (86011'E to 86023'E, 230 00'Nto 23007'N).The iock occurs as lense shaped body within the mica schists, calc-silicates, quartzites and biotite wieisses.'lhe other area of study is Sushnia (22057'N to 86037'E) 40km west of Beldih. Amphibolite saniples are collected From Sushnia. There is an occurrence of apatite body found in Panrkidih along the North Purulia Shear Zone (NPSZ):lherc are some diffi.rences in apatites of these NPSZ and SPSZ. The apatile rocks of these two areas are compared on the basis of petrographic and geochemical analysis (XRF and SIiM).'Fhe trace element data obtained From XRF analysis is also compared with the three major types of apatite-magnetite bearing rocks: Kiruna type, Nelsonite type and Carhonatite t pe. [he comparison shows that the apatites of Purulia are not hydrothermal but of magmatic origin. [lie trace element data are almost Following similar trend with the Nelsonite and Carhonatite type deposits. The study shows that the apatites are formed from primary magniatic melt. The mineralogical, textural and mode of occurrence of the apatite-magnetite body and the apatites suggest that the apatites are associated with carbonatite related magmatism. The presence of Amphiholite suggests there was a metamorphic event along the SPSZ and the texture of hornblende suggests that the metamorphism was before the tectonic activity along the shear zone.