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Victoria University Antarctic Research Expedition Science and Logistics Reports 1979-80: VUWAE 24

Report on Foraminifera from MSSTS 1 (RML, BLW)

Report on Foraminifera from MSSTS 1 (RML, BLW)

We sampled 72 intervals from the MSSTS 1 drill core taken in western McMurdo Sound. Core recovery was 100.15 m, 43.6% of the drilled succession. Our average sample frequency of recovered sediment is 1.4 m. The size of the samples was generally small and became progressively smaller down hole as narrower diameter core barrel was utilized. Sample sizes range from 15cc to 30cc.

Most of the samples proved to be semi-lithified diamictons. To extract the Foraminifera, we originally used the procedure of soaking and boiling each Sample in hydrogen peroxide to disaggregate the sediment. As this proved to be insufficient for most of the samples, we attempted to improve break-down of the material by drying the fragments in an oven at 120°C for three hours, then placing them in kerosene to soak overnight. Following this, the samples were removed from the kerosene and boiled in water. This procedure was applied to seven of the samples known to contain Foraminifera. This also proved to be inadequate. A second chemical, dimethyl sulfoxide (DMSO), was used on one sample, 36-5, 17-19cm, on an experimental basis to determine if it would penetrate the sediment and thus facilitate disaggregation. The sediment was boiled in DMSO at 100°C for several hours. This method also did not substantially increase disaggregation of the sediment, and as the chemical is very caustic, we returned to the use of hydrogen peroxide. This time, we preceeded the boiling treatment by crushing the larger fragments of the core samples with a hammer or mortar and pestle. The crushing was first page 24 tried on Sample 36-5, 17-19 cm, to determine the effects on the Foraminifera and other fossil material known to be present in the sediment. It had little or no detrimental effect, so we adopted this technique for all the compacted samples. Table 6 lists the samples and treatment each received.

Further processing included washing, sieving through a 63 micron standard mesh to remove clay-sized particles, followed by floatation in carbon tetrachloride to concentrate the biogenic material. Microscopic examination was then made of the floated portion. Table 7 lists the samples, the contained biogenic material, and the sub-bottom depths from which each sample was taken.