An occurrence of Kawakawa Tephra from the Grey River valley, South Island, New Zealand

Abstract

Abstract A new locality for Kawakawa Tephra from Graham Terrace, near Nelson Creek in the Grey River valley, South Island, is described. The tephra occurs in loess and is clearly visible as a macroscopic layer where the loess is thickest (about 130 cm) close to the presumed loess source at Nelson Creek, to the north and east. Variable tephra thickness (up to 8 cm), lack of layering within the tephra, and inclusion of locally derived minerals are thought to indicate slight reworking. Electron microprobe and X-ray fluorescence analyses of glass separated from the tephra show that it is chemically indistinguishable from samples of Kawakawa Tephra elsewhere. The tephra represents a datum plane of about 20 000 years B.P. Location and recognition of Kawakawa Tephra allows Graham Terrace loess to be correlated confidently with the latest glacial loess found in the northeastern South Island and southern North Island of New Zealand.