Mafic/ultramafic clasts in deformed biotite zone metaconglomerate, Macraes mine, Haast Schist, New Zealand

Abstract

A textural zone 4, biotite zone metaconglomerate cropped out temporarily in metamorphosed Torlesse Terrane rocks at the Macraes gold mine, eastern Otago. This is the highest textural and metamorphic grade at which a metaconglomerate has been recognisable in the Haast Schist. Clasts in the metaconglomerate are largely reconstituted, boudinaged, locally transposed, and are cut by quartz veins. Fuchsite (5% Cr2O3), talc, and feldspathic clasts are recognisable as distinct from enclosing schist. The feldspathic clasts may have been intermediate or mafic plutonic rocks, and the talc and fuchsite clasts may have had ultramafic parents. The clasts suggest that a minor mafic/ultramafic element existed in the largely continental source area of the Torlesse Terrane.

Key words:

• Otago Schist
• conglomerate
• Torlesse Terrane
• ultramafic
• fuchsite