New stratigraphic constraints on the late Miocene–early Pliocene tectonic development of the Aorangi Range, Wairarapa

Abstract

ABSTRACTA revised stratigraphy is presented for the late Miocene–early Pliocene sedimentary rocks of the northern Aorangi Range, Wairarapa. Despite major differences in lithology, the Clay Creek Limestone and Bells Creek Mudstone are shown to be partially coeval, while the overlying Makara Greensand is shown to be a diachronous unit that ranges from late Miocene (Kapitean) to early Pliocene (Opoitian) age. This revised stratigraphy raises questions about the current classification of the Palliser and Onoke groups, and provides new insights into regional geological history. Previous seismic imaging studies have identified an episode of accelerated crustal shortening and deformation in the Wairarapa region near the Miocene–Pliocene boundary. The Clay Creek Limestone has proven to be a useful marker horizon for constraining the timing and style of this deformational episode, which is interpreted to have occurred prior to 7.2 Ma.