Biostratigraphic Study of Eocene Interval in Te Ranga-1

The main objective was to confirm, and if possible better clarify the stratigraphic age relationships and paleoenvironments within upper Kapuni Group strata encountered in Te Ranga-1 between 2084 and 2313 m. The unit was named Te Ranga Member in the well completion report, but later classed as Mangahewa Formation in GNS reports and publications. Previous biostratigraphic work as part of well completion studies identified these strata as deposited in a shallow marine environment. Abundant Triassic palynoflora was also reported. Based on foraminifera and nannofossils, this report shows the Mangahewa Formation age is no older than Kaiatan (Late Eocene) or younger than Duntroonian (Late Oligocene). A Kaiatan to early Runangan (early Late Eocene) age is inferred.