Eastern New Zealand Drifts, Miocene-Recent
Published:January 01, 2002
Lionel Carter, I. Nicholas McCave, 2002. "Eastern New Zealand Drifts, Miocene-Recent", Deep-Water Contourite Systems: Modern Drifts and Ancient Series, Seismic and Sedimentary Characteristics, D. A. V. Stow, C. J. Pudsey, J. A. Howe, J.-C. Faugères, A. R. Viana
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Sediment from New Zealand passes into the north-flowing SW Pacific deep western boundary current (DWBC) to form widespread drifts. South of 49¼S, where the DWBC is reinforced by the Antarctic Circumpolar Current, drifts are small and, in the case of Campbell ‘skin’ Drift, reduced to a veneer over oceanic sediments. North of 49¼S deposition prevails with (1) Chatham Terrace Drifts – 350 km long and 320 m thick deposits around eastern Chatham Rise at 3000 m depth, (2) Chatham Deep Drift – 400 m thick, 300 km long ridge around the 4500–5000 m deep rise base, (3) Louisville Moat Drift – 400 m of sediment within an isostatic depression along Louisville Seamount Chain and (4) Rekohu Drift – a 250 km long, 480 m thick ridge of Oligocene to Recent sediment. These drifts are sparsely surveyed, but two others have sufficient detail to be case studies. North Chatham Drift plasters northern Chatham Rise at 2000–4500 m depth. Drilling recovered 587 m of nannofossil ooze/chalk with cyclical amounts of terrigenous detritus and reworked subantarctic microfossils. Deposition has been almost continuous since the early Miocene. Hikurangi Fan-drift is a 300 km–long lobe, developed down-current of Hikurangi Channel/Fan through redirection of turbidity current plumes by the DWBC at 4850–>5500 m depth. Seismically, the drift core comprises 200–360 m of probable Miocene palaeo-drift formed prior to the Pleistocene inception of Hikurangi Channel when 400 m of fan-drift accumulated.
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Deep-Water Contourite Systems: Modern Drifts and Ancient Series, Seismic and Sedimentary Characteristics
Countourites are a widespread but poorly known group of sediments linked to the action of powerful bottom currents in deep water. Although we know they are especially common along continental margins and through oceanic gateways, they have been surrounded by contoversy since they were first recognized in the early 1960s. Where correctly recognized and decoded they can provide one of the keys to our better understanding of bottom water circulation and of the ocean–climate link. They are part of the spectrum of deposits that confronts the oil industry as exploration moves into progressively greater water depths.
This memoir is an important outcome of the International Geological Correlation Project 432 on Bottom Currents, Contourites and Palaeocirculation. It includes 30 papers involving over 75 key scientists from around the world. Following an introductory state–of–the–art paper by the editors, there are 25 separate case studies on modern drifts and four on ancient contourite series. Each contribution highlights the specific geological and oceanographic setting, bathymetry, physiographic and stratigraphic context, seismic attributes and sedimentary characteristics of that drift. Case studies range from some of the well-documented North Atlantic drifts to those much less known from the Mediterrenean, from important syntheses of the Gulf of Cadiz and Vema Channel Gateway, to completely new data on South Atlantic, Pacific and Antartic margin systems. The four papers on ancient series from Japan, China and Cyprus serve to emphasise the complex nature and subtle characteristics of contourites, which make their identification a scientific challenge.
This volume is dedicated to the memory of Charlie Hollister (1936–1999), one of the founding fathers and pioneers of countourite research.