Late Neogene sedimentation adjacent to the tectonically evolving North Island axial ranges: insights from Kuripapango, western Hawke's Bay

摘要

Kuripapango-Blowhard is a relatively small region in western Hawke's Bay, but one that displays a stratigraphically diverse Neogene sedimentary record. Earliest sedimentation on greywacke basement consisted of late Miocene (?Tongaporutuan-Kapitean) conglomerate, sandstone, and calcareous sandstone of the Blowhard Formation (new). Deposition of siliciclastic and mixed carbonate sediments of the Mangatoro, Te Waka, Kaumatua, and Sentry Box Limestone Formations continued through to late Pliocene (Nukumaruan) time. These sediments are divided into a broadly transgressive to regressive succession that is up to 2 km thick. The lithologies indicate a strong link between sediment supply and active tectonism through time. An initial pulse of uplift is suggested during the late Miocene, followed by widespread subsidence and relative tectonic quiescence. A later, and temporally distinctive period of late Pliocene tectonic uplift in the region has continued to the present day. Contrasts in the sedimentary record in adjacent fault-bounded blocks suggest different sedimentary histories related to whether the fault blocks were uplifted and eroded, or were subsiding and were depocentres for sediment.