The effect of submerged plateaux on Pleistocene gyral circulation and sea-surface temperatures in the Southwest Pacific

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doi: 10.1016/j.gloplacha.2008.07.003
Author(s): Hayward, Bruce W.; Scott, George H.; Crundwell, Martin P.; Kennett, James P.; Carter, Lionel; Neil, Helen L.; Sabaa, Ashwaq T.; Wilson, Kate; Rodger, J. Stuart; Schaefer, Grace; Grenfell, Hugh R.; Li Qianyu
Author Affiliation(s): Primary:
Geomarine Research, Auckland, New Zealand
Institute of Geological and Nuclear Sciences, New Zealand
University of California, Santa Barbara, United States
Victoria University of Wellington, New Zealand
National Institute of Water and Atmosphere, New Zealand
University of Auckland, New Zealand
Tongji University, China
Volume Title: Global and Planetary Change
Source: Global and Planetary Change, 63(4), p.309-316. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0921-8181
Note: In English. Supplemental information/data is available in the online version of this article, at doi:10.1016/j.glopacha.2008.07.003. 69 refs.; illus., incl. 1 table, sketch maps
Summary: Uniquely in the Southern Hemisphere the New Zealand micro-continent spans the interface between a subtropical gyre and the Subantarctic Circumpolar Current. Its 20° latitudinal extent includes a complex of submerged plateaux, ridges, saddles and basins which, in the present interglacial, are partial barriers to circulation and steer the Subtropical (STF) and Subantarctic (SAF) fronts. This configuration offers a singular opportunity to assess the influence of bottom topography on oceanic circulation through Pleistocene glacial - interglacial (G/I) cycles, its effect on the location and strength of the fronts, and its ability to generate significant differences in mixed layer thermal history over short distances. For this study we use new planktic foraminiferal based sea-surface temperature (SST) estimates spanning the past 1 million years from a latitudinal transect of four deep ocean drilling sites. We conclude that: 1. the effect of the New Zealand landmass was to deflect the water masses south around the bathymetric impediments; 2. the effect of a shallow submerged ridge on the down-current side (Chatham Rise), was to dynamically trap the STF along its crest, in stark contrast to the usual glacial-interglacial (G-I) meridional migration that occurs in the open ocean; 3. the effect of more deeply submerged, downstream plateaux (Campbell, Bounty) was to dynamically trap the SAF along its steep southeastern margin; 4. the effects of saddles across the submarine plateaux was to facilitate the development of jets of subtropical and subantarctic surface water through the fronts, forming localized downstream gyres or eddies during different phases in the G-I climate cycles; 5. the deep Pukaki Saddle across the Campbell-Bounty Plateaux guided a branch of the SAF to flow northwards during each glacial, to form a strong gyre of circumpolar surface water in the Bounty Trough, especially during the mid-Pleistocene Climate Transition (MIS 22-16) when exceptionally high SST gradients existed across the STF; 6. the shallower Mernoo Saddle, at the western end of the Chatham Rise, provided a conduit for subtropical water to jet southwards across the STF in the warmest interglacial peaks (MIS 11, 5.5) and for subantarctic water to flow northwards during glacials; 7. although subtropical or subantarctic drivers can prevail at a particular phase of a G-I cycles, it appears that the Antarctic Circumpolar Current is the main influence on the regional hydrography. Thus complex submarine topography can affect distinct differences in the climate records over short distances with implications for using such records in interpreting global or regional trends. Conversely, the local topography can amplify the paleoclimate record in different ways in different places, thus enhancing its value for the study of more minor paleoceanographic influences that elsewhere are more difficult to detect. Such sites include DSDP 594, which like some other Southern Ocean sites, has the typical late Pleistocene asymmetrical saw-tooth G-I climate pattern transformed to a gap-tooth pattern of quasi-symmetrical interglacial spikes that interrupt extended periods of minimum glacial temperatures. Abstract Copyright (2008) Elsevier, B.V.
Year of Publication: 2008
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Australasia; Biostratigraphy; Bottom features; Cenozoic; Chatham Rise; Cores; Currents; DSDP Site 594; Deep Sea Drilling Project; Foraminifera; Geochemistry; IPOD; Invertebrata; Isotope ratios; Isotopes; Leg 181; Leg 90; Marine sediments; Microcontinents; Microfossils; New Zealand; O-18/O-16; ODP Site 1119; ODP Site 1123; ODP Site 1125; Ocean Drilling Program; Ocean circulation; Ocean currents; Ocean floors; Oxygen; Pacific Ocean; Paleo-oceanography; Paleocirculation; Plateaus; Pleistocene; Protista; Quaternary; Sea-surface temperature; Sediments; South Pacific; Southwest Pacific; Stable isotopes; Subantarctic regions; Subtropical environment; West Pacific
Coordinates: S453129 S453128 E1745653 E1745652
S444520 S444520 E1722336 E1722336
S414710 S414710 W1712956 W1712956
S423259 S423259 W1780959 W1780959
Record ID: 2009017127
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands