Tourmaline rocks associated with stratabound tungsten mineralisation in the Bonya Block, eastern Arunta Inlier, central Australia - Products of early or late boron metasomatism?

Tourmaline rocks commonly occur in spatial association with coarse-grained scheelite-bearing calc-silicate rocks (oxidised magmatogenic tungsten skarns) in the Bonya Block, eastern Arunta Inlier, central Australia, in a Palaeoproterozoic supracrustal sequence interpreted as a distal rift. Emplacement of Late Strangways granites and pegmatites post-dates the peak of M1/D1 low-P metamorphism at c. 1.73 Ga and is early to syn-M2/D2. Field relations, petrographic and geochemical studies indicate that boron metasomatism also post-dates the peak of low-P metamorphism and that tourmaline rocks mainly formed by reaction of boron-rich magmatic-hydrothermal fluids with clastic sedimentary protoliths.