Lithostratigraphy of Paleozoic metasediments in southern Fiordland, New Zealand

Abstract

ABSTRACT The lithostratigraphy of Early Paleozoic metasediments from southern Fiordland is described, with three groups and 14 formations formally defined. In southwest Fiordland, the Fanny Bay Group is a quartz-rich succession of metamorphosed sandstone, mudstone, and quartzite; the Cameron Group is a lithologically variable succession of metavolcanic, psammitic, pelitic and calc-silicate rocks; the Edgecumbe Group is a volcaniclastic succession of metaconglomerate, metasandstone, and metabasalt. South-central Fiordland schists and gneisses are subdivided into either amphibolitic, pelitic, or psammitic lithological associations. Based on fossils, detrital zircon ages, intrusive relationships, and correlation with rocks in northwest Nelson, Fanny Bay Group is most likely latest Cambrian to Late Ordovician whereas Cameron and Edgecumbe groups, together with the south-central Fiordland metamorphic rocks, are likely to be middle to late Cambrian. Fanny Bay lithostratigraphy most closely matches that of the Buller Terrane of northwest Nelson, whereas the Edgecumbe Group most closely matches the northwest Nelson Cambrian lithostratigraphy of the Takaka Terrane. Cameron Group and south-central Fiordland metasediments are similar to each other but their relationship to northwest Nelson rocks is unclear. The Old Quarry Fault separates the Fanny Bay Group from the Edgecumbe and Cameron groups, and is probably a southern continuation of northwest Nelson’s Anatoki Fault.