Transport of Core (DBW)

Forty-one boxes of core were transported from the drillsite to Scott Base by U.S. Navy Helicopters, Power Wagon and octago sledge pulled behind by a D4 crawler tractor.

Although some core damage has occurred, mainly in the larger size HQ and NQ cores, this is attributed to drying out of the core, rather than damage due to transport. No difference in core preservation was observed between the different modes of transport.

The first 2 1/2 metres of core recovered, considered to be from a frozen layer deteriorated rapidly. No deterioration in the consolidated material occurred.

Storage and processing at Scott Base:

Transport to New Zealand:

Core boxes were packed into a wooden cargon which was consigned from Scott Base about the 5th of December.

It was despatched from Christchurch on the 7th December, by rail to Wellington where it arrived on the 21st December. The cargon was picked up by carrier and arrived at the Geology Department on 28th January.

Core condition:

Little physical damage to the core occurred during transport back to New Zealand although a fair amount of relative movement of core pieces occurred within individual boxes.

A preliminary investigation by Dr Ann Bell (Botany Department, VUW] showed the presence of Hyphomycete fungi in four of the forty-four boxes, growing on core labels (gummed paper) wooden blocks and in some cases on the core.

Fungi growing on the core labels was either Penicillium sp or Paecilomyces while an Actinomycete, possible a Streptomyces sp, with very fine hyphae and chains of cauidia was growing on the core. Neither organisms could be mistaken for pollen grains.

Core Photography (AHR)

Duplicate photographs of boxed core were made with both FP4 black and white film and Ektachrome 200 colour slide film. The core was photographed following the insertion of wooden blacks showing core number and sub-bottom depth and where possible prior to both core description and sampling.

Two 35 mm cameras with 50 mm lenses, mounted 1.1 metres above the core on adapted tripods were used. A Sunpack model 411 electronic flash was used for lighting with a double layer of tissue taped to the front to diffuse the light. A centimetre scale, Kodak colour separation guide and grey scale were used and are visible in each photograph.

The black and white film was processed at Scott Base and printed on 10 × 8 Ilfospeed grade 3 paper. These photographs were found to be extremely useful for both locating sample positions and for general use.

Colour film was processed in New Zealand.

Core Sampling (DBW)

535 samples for ten investigators were collected from the core during the drilling period (Table 6). Each sample is recorded in a sample register and the position labelled with the investigators initials in the core box. This should enable sample localities to be accurately located even if some disturbance of core occurs during transport or handling.

Samples have been defined by core and sections numbers respectively and measured in centimetres from the top of each section. Sub-bottom depths for each sample are calculated by adding this distance in centimetres to the sub-bottom depth of the section top.

Core Description (PJB, BC McK)

The detailed cote description was carried out at Scott Base, and the summary logs on a scale of 1:50 are being prepared along with photographs of the boxed core, for publication in the VUW Antarctic Data Series. A log of the hole with the main lithologies is given in Figure 9.

Although a procedure for description was outlined in the Scientific Operations Handbook, pressure of time, facilities and differences in background of the four people involved lead to some unevenness in the descriptions. This problem is being overcome by reference to the core to check the summary logs. However, it is now clear that it would have been more satisfactory to carry Out a small full description at the drill site.

The strata cored at MSSTS 1 represent a moderately varied sequence of diamictite, muddy sandstone, sandy mudstone and well-sorted sandstone in units from a few to about 30 m thick. Pebbles and a few cobbles are scattered throughout, floating in the mud and sand and indicating a continuous glacial influence in sedimentation. Preliminary paleontological data [HTB; SML, BLW in this report] indicate that the sequence is entirely marine and. from 32 m to the oldest core, is mid-Miocene in age. The younger strata are Pliocene to decent in age. The MSSTS 1 core contrasts with the Late Miocene-Recent cores from nearby DVDP 10 and 11, in lower Taylor Valley, in that it is wholely marine, the amount and size of coarse debris is less and there is much less textural diversity.

Lithology

Three main lithologies are recognised in the core recovered; diamictite, muddy sandstone or sandy mudstone, and sandstone. The diamictite is characteristically a non-stratified, very poorly sorted muddy sandstone with evenly scattered pebbles and cobbles forming 1 or 2 percent of the rock. However, all diamictite units include some intervals of stratification. The muddy sandstone and sandy mudstone units also have scattered pebbles, but are better sorted and lack the granule and coarse sand components of the diamictite, and are widely, if faintly, stratified. An indistinct mottling, attributed to bioturbation, is also common. The third lithology is the non-stratified homogeneous well sorted medium grained quartzose sand that forms unit 12. It is far more mineralogically and texturally mature than any other sediment encountered, the size and roundness of the groups indicating direct derivation from the Devonian quartzose sandstones 50 km inland.

Deformation

Soft sediment deformation occurs in many parts of the core, but is more marked in Units 9 and 10. Three types are recognised: page 21

1. Wavy bedding. Stratification is slightly undulose with an amplitude of only a few centimetres, and occurs almost wherever stratification can be discerned. It is thought to have formed at or soon after sedimentation.
2. Inclined bedding. This was mainly confined to the interval from 145 to 1B6 metres. Inclinations of 20 to 40° are common, though at 157 and 182 m stratification is vertical. No overturning was recognised.
3. In situ brecciation of at least partly lithified strata, usually accompanied sand injection. This is common between 148 and 156 m, and was also seen elsewhere (e.g. 126 m).

Diagenesis

The upper 12 m of the hole are unconsolidated sediment, but below this the resistance to the bit increased dramatically and the subsequent core from level to the bottom of the hole, showed a high degree of lithification, reflected in the sonic velocities of 2 to 3 km.s⁻¹, which record an irregular increase down the hole (Table 2). Highly cemented layers of the order of a metre thick occur at a number of levels below 140 m, and several are correlated with seismic reflectors (Table 3, Fig. 9).

Conclusions

1. The texture of the Miocene core from MSSTS 1 suggests moderately rapid sedimentation from debris laden melting ice below wave base. The diamictites were probably deposited when the glacier front was closer and soma intervals may have resulted from grounding of the ice, but there is no clear evidence of this.
2. Extensive and complex soft sediment deformation within Units 9 and 10 may have resulted from shearing by ice, or slumping due to depositional instability. For Unit 10 the alternation of inclined and horizontal layers with no indication of ice contact suggests the latter.
3. Composition of the core suggests it was derived from the Transantarctic Mountains to the west, mainly from the Devonian quartz sandstones of the Beacon Supergroup below 142 m, in contrast to a significantly higher basement component above that level.
4. The degree of lithification suggests that the sequence below 12 m has been buried at least a kilometre at some stage in its history.

TABLE 5 Summary of Core Sampling

Figure 9 Stratigraphic column for MSSTS 1.

Smear Slide Analysis (BW)

The core was sampled for smear slide analysis at varying intervals depending on lithology.

Cadex was used as a mounting media and after initial problems in its application, proved to be a reasonable substitute for Canada Balsum. The slightly higher refractive index of cadex did not allow differentiation between Ca and Na plagioclase feldspar.

The smear slide analysis proved useful in determining sediment texture (sand: silt: clay ratio), mineralogy of the sand size fraction and nature of the biogenic component.

Micritized carbonate (micarb) often occurs in large quanities, probably derived from the dissolution of foraminifera and other calcareous fossils or from erosion of marble basement rocks in southern Victoria Land. No calcareous nannoplankton were observed in the smear slides. Micarb appeared at 40 metres (s.b.) and occurred consistently to the bottom of the hole.

Coarse-grained, well rounded quartz, with occasional silica overgrowth, characteristic of Beacon Sandstone sediments were found in significant proportions at 130 metres (s.b.).

The smear slide analysis has proved to be useful for a quick and effective determination of mineralogical changes that occurred in the core. It is useful for determining the presence of diatoms and was the basis for detailed sampling for diatoms.

The exclusion of the coarse fraction during slide preparation caused a textural bias which resulted in an apparent increase in the amount of mud-size sediment.

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.

Foraminiferal Assemblages

There are two foraminiferal assemblages evident in the samples we collected from the MSSTS 1 drill core. The upper fauna was found in cores 2, 10, 11, 15 and 16. It consists of twelve species, as follows: Trochammina sp., Pyrgo sp., one other species from the Miliolidae family, Fissurina sp., Rosalina globularis, Epistominella exigua, Spirillina sp., Globocassidulina subglobosa, Globocassidulina crassa, Nonion sp. (possibly Elphidium sp.), and a planktonic from the Globigerinidae family (see Table 6). The sub-bottom depths from which this fauna was extracted range from 9.72m to 32.15m. The assemblage consists of several species which are long-ranging in time, making it very difficult to determine an age for the sediments of this upper sequence.

This fauna exhibits some similarities to Pleistocene faunas from the DVDP holes 10 and 11 in Taylor Valley and also to that of the elevated marine deposits of the Cape Barne-Royds area of Ross Island (Wrenn, 1977, Ward, 1979). Rosalina globularis, Epistominella exigua (?vitrea), Globocassidulina crassa and G. subglobosa are found in all three of these sites. Species of Pyrgo, Trochammina, Fissurina, and Trifarina are also found at all three locations, though all those present in MSSTS 1 drill core have not been specifically identified to the species level. None of these taxa are particularly definitive as to time range, but the comparisons of the MSSTS 1 material with the known Pleistocene collections seen to indicate a similar age for the upper fauna of MSSTS 1.

The lower foraminiferal assemblage is also characterized by sparse faunal occurrences. The largest populations are confined to the interval from 118m to 127m sub-bottom (Cores 36 through 39), although scattered tests are found between 63m (Core 29) and 186m (Core 59). The interval from 186m to the bottom of MSSTS 1 (229m) appears to be barren of Foraminifera. Fifteen species are recognized in this lower assemblage: ?Verneuilina sp., Fissurina cf. annectens, Cassidulinoides parkerianus, C. ?porrectus, Epistominella exigua, Rosalina globularis, Elphidium Sp., Trochoelphidiella sp., Cribrononion cf. magellanicum, Globigerina quinqueloba, ?Candeina sp., Eponides tumidulus, Ehrenbergina sp., Nonionella bradii, and Anomalinoides sp. Two of these species are also present in the upper assemblage.

The small size of the lower foraminiferal assemblage and its sparse occurrences put some constraints on age determination. This fauna has strong similarities to the early and mid-Miocene assemblages from DSDP Sites 270, 272 and 273 in the Ross Sea (Leckie, Koch, D'Agostino, these in progress). The planktonic foraminiferid Globigerina quinqueloba has a New Zealand range of Otaian (early Miocene) to Recent (Jenkins, 1971). A potentially useful bioseries in the genus Trochoelphidiella Webb has been recognized in the early Miocene sequence of DSDP Stie 270 (Leckie, in progress). Continued investigations of Trochoelphidiella sp. from MSSTS 1 using the scanning electron microscope may permit better age resolution and correlation.

The preservation of the Foraminifera from MSSTS 1 is generally moderate to good. The tests have a characteristic yellowish color, differing from the clean white forms found on the floor of McMurdo Sound today. The presence of fragmented diatoms, sponge spicules, and other macrofossil debris as well as stratification of the sediments, suggests some reworking. There is no clear evidence for mixing of foraminiferal faunas of different ages. This observation, along with the quality of preservation, argues against extensive recycling of sediments. The very low abundance of Foraminifera may, in part, be explained by the small sample sizes. Oceanographic conditions page 25 influenced by the glacial regime prevalent at the time of deposition on an unstable sea floor may also be important factors inhibiting benthic productivity.

TABLE 6: Samples and processing techniques for foraminifera for MSSTS 1

TABLE 7 Foraminifera and other biogenic material recovered from MSSTS 1 cores.

Report on diatoms from MSSTS 1 (HTB)

Two hundred and thirty samples (approx. 5 cc) were taken from the MSSTS core at Scott Base for fossil diatom analysis. These were treated with Hydrogen Peroxide in the U.S. Thiel Earth Laboratory at McMurdo and smear slides were made using Naphrax as a mounting media.

Fossil diatom fragments occur in at least 60% of the samples. Preservation is poor and identification difficult. No samples have been found which can provide an easy key to the stratigraphy such as occurred in DVDP 10 and DVDP 11. There is so much evidence of reworked Middle Miocene material that this author provisionally interprets the core interval from 35.43 m to 222.43 m as sediments scoured from ancient Miocene fjords during the uplift Of the Transantarctic Mountains.

So far, no Pliocene or Pleistocene diatoms have been found in the 38.43 −222.54 m interval. This suggests a Miocene age for the material even if it has been reworked. Fossil diatoms themselves indicate a Middle Miocene age with close affinities to the RISP J9 cores. No subdivision of this large interval has yet been found except there are some intervals barren of fossil material (148.63 - 167.17 m and 186.09 - 213.70 m).

The upper section 9.71 m - 21.70 m is different. Even though the majority of diatom fragments are similar to those in the lower core, non-marine diatoms occur. The analysis of DVDP 10 & 11 indicates that this flora is a Pleistocene to Early Pliocene flora which lived in terrestrial lakes, or in freshwater lakes wedged between ice shelves and the land, or in freshwater pools on ice shelf surfaces. As yet no definite date can be assigned to this upper section other than to indicate a Pleistocene - Pliocene age.

In August-September a fuller report will be available on the diatom stratigraphy of the MSSTS core. There are some intervals which may provide some control if the diatom fration can be concentrated by heavy liquid techniques.