Napier Complex

The Napier Complex in East Antarctica is probably the most famous UHT terrane, largely because it is the location where the concept of regional UHT metamorphism was first recognized. Despite the early recognition that the UHT metamorphism there affected nearly 100,000 km2 of crust, the duration of this event(s) remains the subject of ongoing debate. The Napier Complex is characterized by the regional occurrence of UHT mineral assemblages that imply peak metamorphic temperatures of 1,050–1,120°C at pressures of 7–11 kbar

The Napier Complex consists of poly-deformed and potentially poly metamorphosed Archean rocks that crop out along the coast, islands and mountain ranges of Enderby Land in East Antarctica. The rocks within the Napier Complex are dominated by 2,990–2,800 Ma tonalitic to granitic orthogneiss, with interleaved, layered metasedimentary rocks and minor mafic and ultramafic units The terrane has experienced at least three deformation events, some of which are only locally developed The D1–D3 structures and associated fabrics are cut by three generations of mafic dykes whose ages range between 2,400 and 1,200 Ma. A suite of amphibolite facies shear zones and pseudotachylites are the final deformational phase; activity on these shear zones has been attributed to reworking during the c. 1,000 Ma Rayner event, and 550–500 Ma PanAfrican-related reworking.