Early carbonate veining and gold mineralization in the Timmins camp: Depositional context of the Dome mine ankerite veins

The earliest auriferous veining event in the development of the over 16 Moz gold endowment at the Dome mine was an extensive set of ankerite veins (over 5400 m strike length). The depositional context of the Dome mine ankerite veins has been historically contentious and their role in the mineralization history of the deposit not well understood. We present a deposit wide geochemical study of the ankerite veins and their host rocks, with observations from new underground mapping. Ankerite veining across the mine is almost exclusively restricted to the Vipond Formation, which is Fe rich and tholeiitic in nature. Metamorphic fluids and ankerite vein formation generally focused along flow boundaries in the volcanic sequence, however, carbonatization is ubiquitous. The flows of the Vipond Formation maintain their protolith geochemical signatures as REE, Zr, Al2O3, TiO2, and Y are largely immobile during mineralization and alteration, which mobilized Na2O, K2O, and locally Fe2O3. The ankerite vein structures are reactivated and overprinted by quartz and quartz-tourmaline veining, and gold grade is variable, ranging from