PETROLOGY OF THE CENTRE HILL COMPLEX

Abstract

Field relations of the banded mafic“Ultramafic Centre Hill complex were studied cad a single cross-section of the sill carefully napped and sampled. Modal analyses were completed from thin sections of each specimen. Samples of all specimens were spectrographically analysed for nine elements: calcium, cobalt, chromium, copper, manganese, nickel, titanium, vanadium and sirconium. Thirteen samples, representing the major hands of the complex, wore chemically analysed for the major oxides. Mineral composition variations were determined either by x-ray or optical methods and the trends plotted on a variation diagram. The criteria of classification and the magma differentiation trend were examined and discussed.