Geikielite-Mg.Al.Spinel -Titanoclinohumite Association from a Marble Quarry near Rajapalaiyam Area, Part of the 550 Ma Old Southern Granulite Terrain, Southern India

Abstract

Geikielite and titanoclinohumite in association with Fo-Mg.Al.Spl-Ap-Phl-An-fassaitic Cpx-Chu-Cal-Dol assemblage, are being reported for the first time from a marble quarry in the vicinity of Rajapalaiyam town. This locality forms part of the Madurai block of the 550 Ma Southern Granulite Terrain and exhibits metamorphic P-T conditions ranging from 7–9 Kbars at 800–1000°C as deduced from the Sil-Opx-Grt-Crd-Bt bearing pelitic assemblages. The role of CO 2 in the formation of the granulites has been dealt with most of the papers, but, only recently, attention is being paid to the role of F rich halogenated fluids, in the formation of humite bearing minerals and in the migration of elements like Ti, Zr and REE. The metamorphic fluid activity which led to the formation of the above unique Fo-Spl-Ap-Chu assemblage including the geikielite and titanoclinohumite minerals can be associated with intrusive granites. The charnockitic pods in the deformed calcitic marble zone may also have helped in providing Ti, P, and Zr. K-rich halogenated fluid activity seems to be common to the 550 Ma eastern Gondwana segments.