GEOCHEMISTRY OF AMPHIBOLITES AND ASSOCIATED ROCKS FROM THE CENTRAL AND SOUTHERN UCHEE BELT OF GEORGIA

Amphibolite-dominated rock units are an important component of the Uchee Belt (UB) of Georgia and Alabama. New analyses of amphibolites from southern and central UB (SCUB) allow comparison with previous analyses of northern UB (Hudson Rapids (HR) and Davis Mills (DM)), Inner Piedmont (IP), and Avalon terrane amphibolites. SCUB amphibolites vary more in silica content than northern UB amphibolites with a range from 41% to 54%. However, all these rocks are much less differentiated than samples of amphibolite from Junction City in the western part of the Avalon terrane. On Harker diagrams, SCUB share similar trends in MgO, TiO2 and Al2O3 relative to amphibolites from HR and DM. SCUB and DM amphibolites are alike with respect to total iron content, in contrast to greater total iron in HR. However, HR is depleted in P2O5 relative to SCUB and DM. There is also considerably more variation in the CaO content for SCUB compared to CaO in HR and DM. Although northern UB rocks are subalkaline to tholeittic, the SCUB amphibolites overlap the subalkaline-alkaline boundary. Amphibolite samples from Kendall Creek and a group of ultramafic to mafic rocks from the eastern UB share the least degree of similarity with SCUB and northern UB amphibolites. This presentation will review the geochemistry of these rocks to further evaluate their similarities and differences.