Differentiation of Tholeiitic Basalt to A-Type Granite in the Sept Iles Layered Intrusion, Canada

Canada) is a large igneous body of c. 20 000 km3. From the base to the top, it consists of a Layered Series dominated by troctolite and gabbro, an anorthositic Upper Border Series and a dominantly gran-itic Upper Series. The parent magma of the Layered Series is inferred to be an iron-rich tholeiitic basalt (48 wt % SiO2; 15 wt % FeOt).Whole-rock compositions from the chilled margin, dykes cross-cutting the Layered Series and silicic rocks from the Upper Series display continuous major and trace element geochemical trends ranging from basalts to ferroan metaluminous A-type granites (77 wt % SiO2). Initial 143Nd/144Nd (0·51201^0·51207) and 87Sr/86Sr (0·70353^0·70548) indicate a juvenile-mantle source and minimal contamination by old crust (1^2%) during crystallization. Geochemical modeling, using the MELTS thermodynamic calcula-tor combined with equations predicting mineral^melt equilibri