A CRETACEOUS EARLY TERTIARY MACROTIDAL ESTUARINE-FLUVIAL SUCCESSION -PUPONGA COAL MEASURES IN WHANGANUI INLET, ONSHORE PAKAWAU SUBBASIN, NORTHWEST NELSON, NEW-ZEALAND

Detailed lithofacies analysis of the Puponga Coal Measures Member alon g the western shore of the Whanganui Inlet, northwest Nelson, is based on five measured sections that incorporate parts of the interfingerin g and underlying North Cape Formation and overlying Farewell Formation . Two contrasting depositional systems. lithofacies Association A and B, are recognised on the basis of sedimentary structures, textures, pa leocurrent data, and the local presence of coal and dinoflagellates. A ssociation A1-3, North Cape Formation, which includes the Puponga Coal Measures Member (Haumurian - Lower Teurian), represents a progradatio nal sequence of estuarine, fluvial, floodplain, and mire deposits. Sub environments include: high energy subtidal channels, upper-flow regime subtidal to intertidal sand shoals or flats, intertidal mixed sand/mu d and mud flats, salt marsh, mires, fluvial distributary or crevasse c hannels and levees, and open/closed bays. The overall setting is a mac rotidal estuary over which mires and fluvial deposits prograded. An ab rupt basinward shift in the depositional system is implied by lithofac ies Association B, the Farewell Formation (Paleocene), that represents alluvial plain deposits. Association B is separated from the underlyi ng Association A by an erosional (Lower Teurian) unconformity. This un conformity marks the Pakawau Group and Kapuni Group contact.