ARE THE VINJAMUR ROCKS CARBONATITES OR META-LIMESTONES

New whole-rock rare earth element (REE) data for the metacarbonate roc ks interbedded with schists at Vinjamur in the Nellore Schist Belt of Andhra Pradesh, show low total REE contents (Sigma 9-128 ppm) that are inconsistent with an igneous carbonatitic origin but which correspond more closely with a sedimentary limestone origin. The REE data of the se rocks however, do not give absolute discrimination between marbles of meta-limestone and metacarbonatite origin. Micro-probe analytical d ata give better discrimination, and the chemical compositions of the c alcite, micas, amphibole, plagioclase, apatite, monazite and staurolit e in the Vinjamur marbles give strong and consistent evidence of a met amorphosed sedimentary rather than an igneous origin.