The stratigraphy and chronology of the Hawera Series marginal marine succession of the North Canterbury coast
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Hawera Series sediments of the coast of North Pegasus Bay are ideally suited for the study marginal marine stratigraphy and facies relations, and for examining the effect o the interaction of tectonic deformation and glacioeustatic sealevel fluctuation. Througout Hawera Time, the patterns of coastal change and changes in river behaviour appear to have been cyclic and repetitious. The coastal belt has been affected by four major transgressions of the sea, viewed the have resulted from retrogradation of the coastline and inundation of the land as the sea rose in level eustatically to consecutive interglacial high stands. Each transgression is referred to a stage of warming and succeeding warmth, and has been named after the coastal platform so formed. The Leonard-Stonyhurst-lit Seddon platform is referred to the Waiwheran Stage, the Bobs Flat-Motunay (older)-Manuka Bay to the Terangian, the Tiromoana-Motunau (younger)-Port Robinson to the Oturian, and the Amberley Beach to the Aranuian. Subsequent to each high stand of the sea, there was a regression, thought in part to have resulted from coastal progradation and in part from eustatically sealevel as climate deteriorated towards glacial conditions. Regressive withdrawal of the sea was accompanied by mantling of the emergent coastal plains and strong river aggradation. The Waimaungan glacial episode resulted in the deposition of the Bennydale Formation, the Waimean in the deposition of the Teviotdale Gravel and the lit. Gerrard Formation, and the Otiran of the Seadown, Tormore, and Wharenui Foundations. During emergence, each coastal plain underwent a complex pattern of regressive mantling with littoral strata, and non-marine alleviation. Non-marine strata can be divided into various facies, each with its own sediment characteristics, lithology, geometry, and fossil assemblage. The Facies are representative of paludal, alluvial fan, fan-plain, and stream, environments. Tectonic deformation has apparently been active throughout Hawera Time.