FLUORAPATITE FROM ALKALINE PEGMATITES OF THE KERALA KHONDALITE BELT -A PETROLOGIC AND FLUID INCLUSION STUDY

We report the occurrence of primary apatite crystals in association wi th graphite within alkaline pegmatite dykes in the Kerala Khondalite B elt (KKB). Petrologic and X-ray diffraction studies identify the miner al to be fluorapatite. Fluid inclusion studies show that the fluorapat ites contain abundant CO2-rich inclusions with densities in the range of 0.85-0.72 gcm(-3). A subsequent generation of trail-bound CO2-H2O i nclusions with low salinity were entrapped along hydraulic cracks. The abundance of CO2-rich; inclusions, and the intimate association of fl uorapatite with fluid-precipitated graphite suggest that the pegmatite dykes hosting fluorapatite were rich in CO2-dominated fluids. We iden tify that among the magmatic conduits proposed for the transfer of CO2 -rich fluids in granulite processes in the KKB, the fluorapatite and g raphite bearing pegmatites reported in this study form important examp les.