Modern shelf carbonates and Neogene on-land equivalents have formed upon and adjacent to the New Zealand sector of the convergent Australia-Pacific plate boundary. They are exclusively skeletal hashes, dominated by bryozoans, bivalves, barnacles, and foraminifers, typical of nontropical foramol carbonates. Tectonism has influenced carbonate formation by determining terrigenous sediment supply rates and therefore the dilution factor and has affected the structure of the sea floor by forming imbricate thrust ridges and fault-bounded platforms that support the carbonates. The Neogene limestones are more abundant closer to the plate boundary than their modern counterparts, reflecting an increase in tectonism with time. In the late Pliocene, sea-level movements combined with uplift of the forearc and transform basins to form widespread limestones only during the glacials.