Characteristics of miocene to pliocene sandy units in the Hikurangi forearc, North Island, New Zealand

This study was conducted to determine the petrographic characteristics, provenance, and reservoir potential of sandstone in the Wairoa syncline of North Island, New Zealand. Three intervals within the Middle Miocene to Pliocene section (Tolaga and Mangaheia Groups) were measured (total420 m), described, and sampled at spacing ranging from 2 m to 20 m. These outcrops consist primarily of thinly to medium bedded, moderately hard to hard mudstone and fine-to medium-grained sandstone with minor fossiliferous sandstone and limestone. Cretaceous to Lower Miocene outcrops northwest of the section area were also described and sampled. (See more in text.)