Stratigraphy of the lower Maitai group at west dome, southland, New Zealand

Abstract

Five formations (Upukerora Formation, Wooded Peak Limestone, Tramway Formation, Little Ben Sandstone, and Greville Formation) representing the lower to middle Maitai Group are mapped on the southern flanks of West Dome, northern Southland. The rocks are dominantly redeposited volcaniclastic sediments and include breccia, conglomerate, sandstone, mudstone, and tuff, as well as redeposited atomodesmatinid (bivalve) limestone. Felsic tuffs are unusually abundant in the Tramway Formation and Wooded Peak Limestone at West Dome. A new unit, the Waitaramea Member, is introduced for distinctive strata in the upper part of the Wooded Peak Limestone characterised by devitrified felsic tuff, red mudstone, and reddish green sandstone. The biostratigraphic age of the lower Maitai Group on West Dome remains poorly constrained but bryozoan genera described from fossiliferous conglomerate lenses in the Wooded Peak Limestone confirm a late Early Permian to Late Permian age. These incude Dyscritella, Paralio‐clema, Fenestella, Maychella, Shulgapora, and others. Trace fossils are locally abundant in the Wooded Peak Limestone and Tramway Formation, and include Scalarituba, Pla‐nolites, and Lophoctenium. Lower Maitai strata at West Dome are overturned, dipping steeply to the north. They are weakly metamorphosed and contain abundant fine‐grained authigenic minerals including both lawsonite and laumontite.