Brief description
Core MD88-779 was taken during the 1988 French ASPARA IV cruise in the South East Indian Ocean aboard the Marion DuFresne. The core was situated on the South Tasman Rise (47º50.690S, 146º32.750E) at a depth of 2260m. Although the core recovered was 6.7m long, only the top 2.6m were studied as preliminary investigations had indicated that this section covered the last two glacial cycles.Isotopic analysis was performed on tests of the benthic foraminifera Cibicidoides wuellerstorfi. The record contains two climatic cycles that reach into isotope-stage 7. The benthic isotope curve of core MD88-779, however, shows a melding of isotopic stages 3-5, which are difficult to separate with depth.
The age-model is derived through comparison with the benthic SPECMAP stack of Martinson et al. (1987). The core covers 200kyr over 260cm, and thus has a low sedimentation rate. It also shows a reduction of sedimentation from the Holocene rates to that of the last glacial (oxygen-isotope stage 2).
The complete loss of a diatom record at 170cm and 210/220cm in the core is extremely unusual. The diatom signal is interpreted as having been removed by increased water mass velocity, extreme post-depositional silica dissolution or decreased productivity. There is no sedimentological evidence from the core which provides further interpretation.
Lineage
Maintenance and Update Frequency: notPlannedThe method used to produce diatom slides from sediment samples is described in the 'methodology' document uploaded with this record.
Parameters: Oxygen-isotope core depth (cm), delta 18O from benthic foraminifera (C. wuellerstorfi), tie points in SPECMAP age scale (ka), corresponding SPECMAP age scale (ka), linear sedimentation rate (cm/ka), diatom core depth (cm), Analyseries extrapolated age scale (ka) at 10cm intervals, core sample dry weights (gm), field of views counted, diatom subtotal, number of diatom frustules (x1000000)/gm dry weight.
Notes
CreditMountain Mass Spectrometry Laboratory (Colorado)
Institute of Antarctic and Southern Ocean Studies (IASOS)
Institut Français pour la Recherche et Technologie Polaires (IFRTP)
Terres Australes et Antarctiques Françaises (TAAF)
Australian Postgraduate Research Award (APRA)
To reconstruct the first sea-surface temperature and sea-ice record history of the Southern Ocean south of Australia.
Issued: 29 08 2007
Data time period: 1988 to 1988
text: westlimit=146.5; southlimit=-48.00; eastlimit=147; northlimit=-47.50
text: uplimit=2266.7; downlimit=2260
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Methodology - Diatom preparation from sediment samples (App 1-1.pdf)
- global : 5e15b270-5a86-11dc-bd3f-00188b4c0af8