Whitianga group sediments of the Table Mountain area, Coromandel peninsula

Abstract

A lower to mid-Pliocene sequence of rhyolitic Whitianga Group sediments is described and one new formation erected. The Wainora Formation includes basal rudites overlain by finer epiclastic lake sediments containing leaf and freshwater mussel impressions. It has a maximum thickness of 35 m and is inferred to have been deposited in two lakes on the dissected surface of the Beesons Island Volcanics' andesites. Conformable on the Wainora Formation are thicker (450 m maximum exposed thickness) and more extensive water-deposited and subaerially-deposited pyroclastic sediments and rarer ignimbrites of the undifferentiated Coroglen Subgroup. Many of these water-laid deposits are inferred to be the result of hot pyroclastic flows entering a valley system having lacustrine, fluviatile, and flood-plain environments. The paleogeography and eruptive history of the Whitianga Group in the Table Mountain area are inferred.