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Four separate projects involving nine people were approved by the Ross Dependency Research Committee for the 1982-83 field season:
Dr. Dibble was to continue his survey of seismic activity on Erebus volcano as part of an international programme. Transmission of data from sensors in the summit area ceased in July and an important task was to get transmission started again.
This project was planned in two parts - (1) an operation on the sea ice to recover cores and survey the Mackay Glacier Tongue in Granite Harbour, followed by a seismic survey for sub-seafloor structure in the southwest corner of the Sound, and (2) a shipboard programme of bottom sampling and bathymetry.
Although most work was directed toward understanding modern sedimentation, an important part, and especially the seismic work, was to provide more information on drill sites proposed for 1984 and 1985 as part of the CIROS project.
An extensive field programme around the head of the Dry Valleys was planned for Mr. Walker, who is working on the character of the river system that existed in Victoria Land during Triassic times. Because of the importance of climatic information a more detailed study of Triassic soils and vegetation was proposed.
A limited field programme was proposed for Dr. Korsch, recently appointed lecturer in structural geology, to introduce him to the basement rocks of the Dry Valley region, and to tackle the origin of rocks and structures on Shapeless Mountain, a volcanic-sedimentary complex.
The areas studied by VUWAE personnel are shown in Figure 1.
A grant of $16,960 was obtained from the University Grants Committee to run the expedition. This was to cover food, travel and freight, insurance, field clothing and some scientific supplies for the 9 VUW personnel. The university's Internal Research Committee provided a total of $9,460 for the three student expedition members, for the purchase of a JMC depth sounder,
A new portable winch capable of depths to 1000m was built for the sediment sampling programme by the Wellington firm, Accrescent Engineering. The VUW Engineering Workshop made the winch wire laying system and a load cell for measuring the tension on the wire.
The major part of the underwater camera housing was built in stainless steel by Centralloy Industries in Christchurch. The camera system which is being developed at VUW is designed to be deployed both from sea ice and shipboard platforms.
New equipment purchased this year consisted of a dual frequency echosounder used primarily for bathymetry surveys from the sea ice and a "Halda Twinmaster odometer" which was fitted to a toboggan for distance measurement. An accuracy of 5m per kilometre is expected over most sea ice "terrains".
Four new cargo boxes for scientific equipment were built in the Geology Department and orange peel grab and tide gauge recording mechanism borrowed from other departments within the University.
Two new sets of "Polar" sleeping bags and four sets of field clothing were purchased to replace worn stock.
1982 was our best year so far in terms of data collected. The summit induction loop, which was broken by a bomb, was repaired by W.I. McIntosh, R. Mason and party plus Helo on 25 January 1982, and recording tapes up to 16 February were dispatched to Japan before the last flight out. All sensors, transmitters, receivers and recorders were fully operational until late May when the loop stopped working. Abbott transmitter died in early June. Early on 21 July, Summit, Hooper and Bomb began recording a swarm of earthquakes. On 22 July they were occurring every minute or so, and died away during the next 3 days. There were vague reports of a glow in the sky on or about 21 July at this time.
By the 3rd of August, the Summit, Bomb and Abbott transmissions had all become very weak and intermittent, but Hooper and Terror were still O.K. Terror dropped out by 11 August, and on 17 August, Ross Mason wrote that all the equipment had stopped working. Fortunately, he did not turn the receiver/recorder off, because by 23 August there was enough sky light reaching the solar cells to revive Hooper and Abbott. Bomb was intermittent until about 24 September, but Summit stayed dead because it did not have a solar cell.
When the Japanese party (Kaminuma, Ueki and Koyama) arrived at McMurdo in November they examined the recordings from 23 August onward. Between 13 and 25 September, earthquakes were recorded at a rate of 92/day (average). From 25 to 30 September it was 117/day and then jumped to 184/day until 2 October, after which it was again 117/day until 7 October.
Suddenly at 0248 UT on 8 October a swarm of earthquakes began. In the next 24 hours at least 640 earthquakes occurred, initially separate earthquakes and with sharp P and S phases at Abbott (the closest station); S-P 2.8s), but after a few minutes continuous tremor began, and clear P and S phases were not often discernible. Five of the best recorded earthquakes in the first 7 minutes were grouped near Fang Ridge under the Fang Glacier.
Within a day after the swarm, earthquakes were back to 106/day, and slowly declined to 74/day by 9 November, the date up to which the recordings have been replayed.
Observations were made of Erebus crater activity in the 13 day period over which equipment in the summit area was being repaired, and are presented in Table 1.
This season a relatively small bathymetry and seafloor sampling programme was designed to cover an area in the southwest corner of McMurdo Sound, which we had not previously sampled and also to start a detailed study in Granite Harbour. Samples were collected in front of the Blue Glacier and 10km east of Cape Chocolate near the Dailey Islands. In addition, bathymetry transects were done in this area and for 3km off Scott Base.
Granite Harbour can be considered a "closed basin" which collects sediment deposited from the Mackay Glacier Tongue. Study of this "sedimentation system" will enable a more precise interpretation of the marine glacial contribution to recent McMurdo Sound-Ross Sea sediments and the older Cenozoic sediments that will be cored in the next few years.
The other major part of the sea ice programme was in support of CIROS, and comprised seismic refraction studies for drill site location at Butter Pt., Dailey Islands, sea ice movement monitoring off Butter Pt and tide movements at Cape Roberts. The only project not completed was seismic refraction work east of Cape Roberts which was to be a co-operative project with Northern Illinois University. A spreading crack in the sea ice 3km east of Cape Roberts could not be crossed by bulldozer (D4) or the vehicles used by the seismic party.
The 1982-83 GHSS science programme can be considered successful not only due to the favourable results obtained this season but also as a result of the initiation of long-term monitoring, (glacial movement and sedimentation rates), where results will not be available for a year or more.
In an attempt to determine both rate of movement and amount of plastic deformation of the Mackay Glacier Tongue, a network of eight poles was established up and down glacier from the grounding line, and was subsequently surveyed by K26. Difficulty was experienced in identifying the poles using a theodolite alone, and it proved necessary to have people moving to each successive pole on the glacier at the time of surveying.
Collection of undisturbed bottom sediment enables detailed paleontological and sedimentological studies of various core to be related spatially
In both cases, corer penetration appeared to be stopped by a coarse sand layer observed at the base of each core. It is unlikely that the addition of more weight would have increased the penetration. Distinct black mottling, thought to relate to reducing conditions at the time of deposition (and shortly after), was observed in both cores, and in addition, a general fining up sequence was recognised in core 83/2.
Sediment traps enable the capture of settling sediment within a known area and hence are a quantitative method of estimating rates of sedimentation.
Two traps were deployed at depths of 400m and 750m respectively, immediately east of the Mackay Glacier Tongue. It was planned to retrieve these traps during February 1983. However, due to calving of the Mackay Glacier these traps were lost.
A sediment trap was later successfully deployed using the "USCGS GLACIER" (see Part II).
Currents have the ability to distribute and rework sediment, but the importance of currents within a semi-enclosed basin such as Granite Harbour is not widely known.
A "savonius rotor" current meter which measures currents greater than 0.02m/sec−1 was used immediately east of the Mackay Glacier snout at 1/2 hour intervals, at depths of 5, 10, 20, 40, 60, 80, 100, 150, 200, 400, 650 metres. The programme was terminated when no measurements were recorded at any depths after 4 consecutive hours of monitoring.
A "spreading crack" formed in sea ice has been encountered east of Cape Roberts during the last two seasons (December 1981, November 1982). The crack has proved impassable by heavy surface transport (D4 and IH500 bulldozers) thereby preventing access further seaward. This season the crack was visited twice in November (6th and 18th) and detailed measurements were made both times at the same site.
On November 6, 1982 the crack was located 2.91km due east of Cape Roberts. It was traced for 5km south and north, and remained undiminished over the total 10km. The orientation was northwest-southeast over this short distance but it is thought to curve towards Mt Bird further south based on previous seasons' sea ice breakout observations. North of Cape Roberts the crack cut close to a distinctive grounded iceberg, as it had done in December the previous season. While the location and orientation of the crack is not yet well known it has probably been the same in both the 1981-82 and 1982-83 seasons.
The spreading crack is filled with ice that has a ridged and terraced surface and thins towards the central crack (Fig. 2). On November 6 the distance between the edges of the first year ice where initial rifting began was 33m. Ice cores were taken from the western side of the crack to define the thickness profile of the infilling ice on November 6 and 18 (see Fig. 2). Two pegs straddling the central crack were fixed in the ice on November 6 and resurveyed on November 18 to determine a spreading rate for that period. The total spreading for the 12 days was 1.2m (10cm/day) and 24 "growth lines" that ranged in width from 2.5 - 10cm were counted in the new ice. The growth lines for this period appear to form daily probably at "night" when temperatures are cooler. The variation in width of the growth lines and terraced surface of the infilling ice indicate that the spreading rate is not constant and was probably greater earlier in the season.
A tide gauge designed to automatically record tidal amplitude was established on the sea ice for 11 days at both Scott Base and Cape Roberts. The tide gauge is similar to that described in Pyne and Waghorn (1980) and records tidal amplitude by measuring the relative movement between the floating sea ice and a counterweighted line anchored to the seafloor.
At Scott Base recordings were made from 19-30 October in 80m of water approximately 200m off Scott Base. Unfortunately, good records were only obtained during the first five days (19-24 October), but showed a maximum tidal range of 0.75m for this period. Later recordings at Scott Base appeared to be dampened due to ice freezing on the steel anchoring wire immediately below the sea ice. The steel wire was replaced by monofilament nylon at Cape Roberts and no further dampening occurred.
Recording at Cape Roberts was made over the period 8-18 November with a recording break from 10-13 November, due to unwinding of the clockwork recording mechanism. Sufficient records were obtained, however, to show that the tidal cycle at Cape Roberts is similar to other parts of McMurdo Sound. The change from the "higher" amplitude single daily cycle to a "lower" amplitude double daily cycle was recorded. The maximum range measured was 0.76m and it is estimated that no tides would exceed 1m in the area.
These surveys were made to aid the selection of drill sites for the Cenozoic Investigations in the Western Ross Sea, and extended the work begun by lies and Dibble in 1980. The team consisted of Bay Dibble and Ian Paintin (geophysicists), Alex Pyne and Tony Macpherson (geologists), and Malcolm McLeod (mechanic/field assistant). We used the SIE-RS44 and Nimbus 1210 seismographs belonging to the Institute of Geophysics. Each has 12 recording channels, and a 330m cable spread.
At New Harbour, both seismographs were operated in a heated Wannigan, and the Nimbus was used with an extension cable so that the two spreads along the seismic line were 330m apart. Two seismic lines, each 8.66km long with shot points at each end and at the centre, were laid out in the form of a cross with 6 Wannigan sites and 12 evenly spaced spreads on each line. (A 7th site was added in the centre of line B). Lines were laid out dead straight and flagged at 320, 330, 340m intervals by means of a precision odometer fitted to one of the 2 motor toboggans.
Two shooting parties, each with a shot instant tone encoder and Compak radio, fired charges of between 1kg at 5m depth and 8.8kg at 15m depth at all 3 shot points for each Wanigan site. Shot depths were chosen to avoid damaging the shot holes, rather than avoiding bubble pulses. At the Wannigan a Compak receiver and tone decoder started the Nimbus automatically at the shot instant, and the tone code was fully recorded by the RS44. At each Wanigan site a 30cm hole was drilled through the 2m sea ice for the echo sounder, and the water depth was measured.
At the Dailey Islands, Tim Stern and Peter Whiteford (DSIR geophysicists) and Brian Smith (field assistant) joined us with their Nimbus seismograph and Snotrac vehicle, enabling three shooting parties and two separate recording parties to be used. Here, sea bottom depth and dip along the seismic line were determined at each spread by stacking sledge hammer blows on the ice in the Nimbus digital seismograph.
Two 8.66km lines similar to those at New Harbour were laid out in the form of a "T". Four extra shot points were included on line A because a complex sea bottom was expected near the islands.
Work on Cruise IV of USCGC GLACIER (February 12-19, 1983) for the McMurdo Sound Sediment Studies project produced 1200km of bathymetry, much of it in areas previously uncharted, and seafloor samples from 26 sites. Several preliminary conclusions are drawn:
The shipboard programme for the McMurdo Sediment Studies project had three main aims:
The ship's track and stations for bottom sampling are shown in Figure 4. Station data is given in Table 2.
Four deep water grab samples (Stations 3-6, 854-889m) were taken, all mud with a little sand, and rare mainly angular basaltic pebbles up to 8cm long. Biota are sparse with only a few worms and fine sponge spicules. The grab sample was normally sufficiently undisturbed to see a section from the seafloor down 10 to 15cm, which showed the upper 2cm to be soft and slightly oxidised, in contrast to a firmer layer beneath which had dark grey mottles and
Samples from slightly shallower depths (Stations 1, 2, 3A, 7, 8, 26; 547-755m) were also taken for foraminiferal studies by B.L. Ward to cover the range that includes the carbonate compensation depth. Sample 1, a few miles north of Scott Base, had pebbles encrusted with bryozoans, indicating their exposure above the seafloor and again a very low sedimentation rate.
With Granite Harbour virtually ice-free we first carried out a bathymetric survey, 250km of track in an area of about 400km2. The work in Granite Harbour also involved the setting of a sediment trap in 800m of water at the tip of the Mackay Glacier Tongue (to be retrieved in November 1983) and the recovery of 13 bottom samples. The latter were mainly grab samples, but included 2 cores 60cm long and 20cm across for detailed sedimentological study. A grab sample near the middle of the Harbour (Station 16, 849m) contained black mud, but a piston core attempt nearby (Station 16A, 880m) yielded only 25cm of core because the corer encountered stony till, showing that the pattern of sedimentation in Granite Harbour is not simple. The bathymetry is also quite complex for although the Harbour can be described in gross terms as a broad basin almost 900m deep, the floor is hummocky with a relief of 200-300m (Fig. 5B).
A bathymetry line was run east from Cape Roberts and two bottom samples were taken to help with CIROS site selection. The seafloor east of Cape Roberts is sandy or gravelly, even in 489m of water at Station 19, where a boulder of granite 30cm long was taken by the grab. Worm trails of cemented sand over part of the surface of the boulder show that it was partly buried in sand. Grabs from near Cape Roberts and the 108m deep shoal 18km offshore represented a gravel pavement, judging from the encrusting bryozoans and other organisms. Bathymetric data obtained off Granite Harbour can now be used to chart the North-South-trending ridge and West-facing scarp that is cut in the East-dipping sequence to be sampled by CIROS 3 and 4. Some idea of the sequence was obtained from pebbles in the till recovered at Station 8 which is on a broad, flat "delta" surface at 550m. Although most pebbles were granite and presumably from Granite Harbour, a number were sandy mudstone with scattered coarse sand grains, like the glacial mudstones in the Early-Mid Cenozoic MSSTS core. The west-facing scarp was also sampled by grab (Station 11) but recovery was poor and no new lithologies were seen. Nevertheless, we hope that processing the sand fraction may yield micro-fossils that indicate the age range of strata forming the scarp (Pig. 5C).
The bathymetric data obtained on this cruise is significant not only because of new areas charted but also because it confirms our view of a fundamentally different character of the Western Shelf and Slope than shown on previous bathymetric maps, such as that of McGinnis (1973). Earlier maps and
et al., 1974) show submarine valleys extending from the Dry Valleys into the "moat" around Ross Island. However, the Western Shelf is in fact a rather flat feature (average depth 180m) with two very narrow (about 1km) valleys running from its edge to near the foot of the slope. These features seem far too small and well-defined to be glacial in origin, especially when compared with the broad submarine extension of the valley now containing the Debenham Glacier (5km wide and 500m deep) or the 800m deep basin carved by the Mackay Glacier off Granite Harbour (Figs. 5D, E). The lack of broad glacial valleys in the Western Shelf east of the Dry Valleys, in contrast to those cut by the outlet glaciers north of 77 10′S, suggest that none of the Dry Valleys have served as outlet glaciers since the deposition of the near surface strata of the Western Shelf, which at MSSTS-1 are as old as Early Cenozoic (Webb, Leckie and Ward, in press).
The bathymetric data also revealed another feature no doubt seen before, but not to our knowledge taken into account in discussions of McMurdo Sound geology. Tracks along the edge of the McMurdo Ice Shelf showed a hilly topography superimposed on the gentle slope of the Western Shelf (Fig. 5F). Because of the nearby Dailey Islands, scattered basaltic cones that rise to 132m above sea level, these hilly features are also thought to be of volcanic origin. Defense Mapping Agency Hydrographic Center Chart 29321 shows a number of unusually shallow soundings in deep water around Ross Island, and one of these is crossed by Track XXX of Northey et al. (1976), showing it to have a conical section and an apparent height of 165m above the floor of Bird Basin. These are also judged to be of volcanic origin, and may present a significant extension of the Erebus volcanic Province (Figure 1).
Results of the cruise will appear in several different places. Selected samples will be used by Ms B. Ward in her study of the distribution of modern foraminifera in McMurdo Sound, and the Granite Harbour samples and data will be used as part of a thesis on the Mackay Glacier-Granite Harbour sedimentary system by Mr. Macpherson. The bathymetry will be added to an earlier compilation to complete a bathymetric map of McMurdo Sound with the assistance of Geophysics Division and the Institute of Marine and Freshwater Science, DSIR. The samples and bathymetry will also provide the basis for papers on recent sedimentation in McMurdo Sound.
A cruise plan is being prepared for work in February 1984 mainly to carry out further site investigation for CIROS drilling. A shipboard survey has become necessary because sea ice conditions off Cape Roberts prevented the planned "land" based seismic survey off Cape Roberts. The survey will link with previous shipboard surveys in the area. The cruise plan also includes some time for gravity cores from Bird Basin (not collected in 1983 because of equipment problems and
Previous geological investigations of the Beacon Supergroup outcropping on the polar plateau edge of the Transantarctic Mountains have shown that the Triassic strata forming the youngest part of the Beacon were deposited by rivers that flowed over a broad, alluvial plain.
The object of this PhD study has been to visit the better exposed localities of Triassic strata throughout south Victoria Land so as to establish a set of palaeohydraulic models that best represent the fluvial depositional processes that operated during this time.
During the 1982/83 Antarctic field season the excellent exposures at Mount Bastion, Portal Mountain, Shapeless Mountain and Allan Hills were visited. These widely separated localities offered the coverage necessary for understanding the Triassic depositional basin.
The 400 metres of Triassic Lashly Formation is divided into four members. Member A, which is 100 metres thick, consists of laterally extensive trough-cross-bedded and micro-cross-laminated tabular sandstone bodies in the order of 2 metres thick that were formed by the lateral migration of river channels. Straight channels had widths of at least 200 metres but were seldom deeper than 2 metres. The channel sandstones are interbedded with root-bearing mudstones, siltstones and fine sandstones that occur in beds up to 6 metres thick. These beds commonly contain abundant white roots, Skolithus burrows and in some places pedogenic features (Gabites, this report). The fine grained beds are interpreted as overbank sediment that accumulated in a swamp environment.
Member B represents a marked change in river behaviour. Over 100 metres thick and consisting of over 90% sandstone it is dominated by massive, horizontally laminated and trough-cross-bedded sandstones. These deposits are interpreted as being of flood origin. The floods commonly attained upper flow regime conditions, were capable of scouring deeply in older flood deposits and transporting large mud-stone clasts, mats of peat and logs.
The 70 metres of Member C marks another change in depositional conditions. Carbonaceous shales, thinly bedded and laminated siltstones are abundant. Interbedded mudstone and micro-cross-laminated sandstones and coal beds up to 1.2 metres thick are also common. These deposits are interpreted as being formed in extensive shallow lakes and swamps. Vegetation was abundant (Gabites, this report). The common occurrence within Member C of tabular, trough-cross-bedded and micro-cross-laminated sand-stone beds around 1 to 2 metres thick indicate that the paludal environment was occasionally inundated by flood sands of sheet flow origin.
Member D is 200 metres thick and represents conditions similar to Member B.
The sediments of the Lashly Formation were deposited by north-flowing rivers in a cratonic foreland basin now the present site of the Transantarctic Mountains. This basin may have extended south into the Beardmore Glacier area and possibly encroached upon some areas of North Victoria Land (Elliot, 1975; Walker, 1982). Basin width was at least 40 kilometres but most likely in the order of 100 to 200 kilometres.
Uplift of the Ellsworth and Pensacola Mountains supplied sediment to the Nilsen-Mackay Basin (Elliot, 1975). The rate of movement of sediment over the floodplain was largely controlled by differing intensities of tectonic uplift. Members A and C reflect relatively stable periods of crustal movement and near to equilibrium hydrologic conditions. Members B and D reflect deposition from periods of uplift, which provided an abundant source of sediment, increased the gradient of the palaeoslope and increased the amount of subsidence of the sedimentary basin. Secondary controls on sedimentation include a temperate climate with abundant rainfall and a well-vegetated floodplain.
The results of the geological data collected over three Antarctic field seasons will be presented ultimately as a PhD thesis in 1984, and then by a series of papers to internationally recognised sedimentological journals.
The results from this study will firstly provide an understanding of the environment of deposition for the Triassic part of the Beacon Supergroup and secondly will contribute to the understanding of similar alluvial plain deposits found elsewhere in the world.
Four mountains were visited during the nine-week field season to record and sample Triassic plant fossils and palaeosols (fossil soils) with the aim of establishing a model of vegetation on the Triassic alluvial plain. The results of this field work will go towards a MSc thesis. Work will concentrate on describing the Triassic vegetation in terms of communities, soil/plant relationships, climate and palaeohydrology.
Palaeosols with associated vegetation were recorded at Portal Mt. and Allan Hills, and undeveloped palaeosols with root traces at Mt. Bastion.
No macro-fossils were found in the Fleming Member. Well-preserved macro-fossils were recorded in Members A, B, C and D of the Lashly Formation. Equisetalean stems ("horsetails") are abundant in A; well-preserved gymnospermous logs in channel deposits of B and D; and a wide range of flora in lake, swamp and quiet backwater deposits of C, including a rich corytosperm ("seed-fern") assemblage. The corytospermous Dicroidium flora is restricted to the Triassic, but was recorded at Shapeless Mountain in a bed previously designated as Permian Weller Coal Measures.
Member A: At Portal Mt. the oldest recorded Triassic macroflora (Dicroidium) is found at the contact between Fleming Member and Member A. Neocalamitid stems and? Lycopod stem impressions are the most abundant macroflora. Grey-green undeveloped mudstone palaeosols contain white rootlet traces and often have a densely burrowed upper surface where not eroded. Developed palaeosols seen at Portal Mt. display gammate structure and eluviated horizons resulting from periodic waterlogging and drying in a "subhumid" environment. They support a small woody vegetation and large Neocalamitid stems with trunk bases around 6-8cm diameter.
Member B: Where stabilised muds and overbank deposits are preserved, a corytosperm association of 3 or 4 species and Neocalamitid stems can be found. The broad, deep, medium-grained flood channel deposits of Member B contain much coaly and silicified wood material. This may reflect an overall stability of channel course in the region disturbed by infrequent large floods which destroyed forested areas. (Some stumps at Mt. Bastion may be 200 years old). At Allan Hills a flood deposit bearing logs is exposed over almost 0.3km2. Trunks up to 10m in length with roots and branches are oriented with the channel flow; compression ranges from 10-60%. When the flood subsided, large rafts of peat 30cm thick were deposited. The only recognisable fragments in the peat are Dicroidium.
Member C: Rich in fossil material preserved in the shales, coals and carbonaceous sandstone beds characteristic of this member, in particular Dicroidium, Xylopteris and Johnstonia species. At Allan Hills a succession is preserved from Neocalamitid and Gingkophyte swamp vegetation to a drier Johnstonia flora. Approximately 20cm of Johnstonia - rich silt forms the substrate for evenly spaced trees up to 55cm diameter. Field growth ring counts give an estimated age of 100 years for this stand.
Member D: A similar situation on the floodplain as for Member B is envisaged.
Fossil types recorded were: Dicroidium, Xylopteris, Johnstonia, Sphenobaiera, Phoenicopsis, Neocalamites, Lepidopteris. ?Glossopteris, ?Taeniopteris, gymnospermous and ?lycophytic wood, seeds, microsporophylls, roots, infilled root traces, peat, horizontal and vertical burrows.
I can foresee value in extending the region of study at least as far as the Beardmore Glacier area, to compare floral diversity and environments of vegetation growth and deposition, with those 500km further down the alluvial floodplain.
Approximately six days were spent in the Miers Valley on a reconnaissance geological survey of the basement rocks so that Korsch could obtain a working knowledge of these rocks. The Miers Valley was selected because of its accessibility, facilities (Wannigan) and because a 1:25000 geological map which included the northern wall of the Miers Valley had been produced in the 1980-81 field season by G. Mortimer, F. Reid and S. Simmons (see report by Mortimer, 1981).
During our stay in the Miers Valley we were able to examine most of the rock units shown on Mortimer's map. Metasedimentary rocks of the Koettlitz Group include a wide variety of parent lithologies including pure and impure limestone, shale, sandstone, quartzose sandstone and intercalated basaltic volcanics. These rocks have been regionally metamorphosed to amphibolite facies and then suffered localised contact metamorphism during emplacement of various granitic plutons.
Deformation of the metasedimentary rocks produced isoclinal folds, an excellent example of which is well displayed in the Salmon Marble on the north wall of the Miers Valley. A second deformation refolded the first generation structures.
Granitic rocks observed in the field included the Buddha Diorite, Dais Granite, Miers Granite, Rivard Diorite and Grey Granite along with unnamed aplite, pegmatite, lamprophyre and basalt dykes. Wherever contacts were exposed good evidence for the intrusive nature of the plutons was observed. Detailed field descriptions of all the units can be found in Mortimer (1981).
During our reconnaissance study of the ridge between the Miers and Marshall valleys we found that the map of Mortimer (1981) stood up well under scrutiny, although minor modifications should be made. The biggest problem we faced was in the recognition of various plutonic units which in places seemed to grade into each other, but this will be overcome by experience with these rocks. One must question Mortimer's use of the term "Penance Pass Formation" as a suitable term - "Hobbs Formation" already exists in the literature and only needs redefining rather than the introduction of a completely new term.
This study represented an introduction to the basement rocks for Korsch, who is developing a programme to study various aspects of the basement geology over the next few field seasons.
Shapeless Mountain appears so because it is quite irregular structurally in contrast to the consistent near-horizontal stratification in the Beacon Supergroup elsewhere. Shapeless Mountain also has outcrops of the Mawson Formation, which at Allan Hills has been interpreted as volcanic mudflow deposits. The aim of the field season at Shapeless Mountain was to determine the nature of the Mawson Formation, and to study the structural geology in detail to establish any relationship between the structure of Shapeless Mountain and the volcanics of the Mawson Formation.
A detailed manuscript map of the geology of Shapeless Mountain was compiled by P.J. Barrett from earlier VUWAE work and we found this map invaluable during our field work.
Shapeless Mountain can be divided into several geologically distinct areas, based on the relationships between the Mawson Formation, Ferrar Dolerite and the Beacon Supergroup:
in Barrett and Webb, 1973) volcanic breccia and basalt lava flows were interbedded and both occurred stratigraphically above the Lashly Formation. The contact between the two appeared conformable. Barrett and Webb (1973, Section S11) also reported a conformable sequence of Mawson Formation above Lashly Formation on Mistake Peak.
Within the Mawson Formation several lithofacies are present:
Based on our field work at Shapeless Mountain we conclude that the Mawson Formation is a product of volcanic eruptions and subsurface intrusion of magma which occurred at essentially the same time as emplacement of the Ferrar Dolerite sills. The present structure of Shapeless Mountain results from the effects of the intrusions on the host sedimentary rocks.
It is intended to publish at least two papers, one dealing with the relationships between the Mawson Formation and the structure of Shapeless Mountain and the other examining aspects of the lithofacies and geochemistry of the Mawson Formation.
Following this field season, a detailed examination of the Mawson Formation in the Allan Hills would be profitable. Based on observations made by members of K6A this field season the situation is more complex in the Allan Hills than has been described in the literature, and a field season longer than the week proposed by Korsch for the 1982-83 season would be required. This work
The IMESS team this year was as follows:
To improve efficiency and reduce crowding in Erebus Hut, four occupation periods were planned this year, beginning on 24 November with Otway, Currie and Bell, overlapping next with Dibble and Paintin, then Kyle's U.S. party, and finally Ueki and Koyama until the end of December. The weather and the helo operational problems this year made this impossible.
After reaching the hut on 21 December, the whole party was involved in carrying 20 Gel-cell batteries (20 lbs. each) from the hut to the telemetry transmitter site. In the absence of the Alaskan telemetry experts (who spent their grant on equipment for IMESS instead of travel) the New Zealand party installed the new solar panel, serviced the transmitter, and installed a new pressure sensitive microphone (NS LX6002 G) and associated 1700 Hz preamp/VCO. The new microphone is a temporary inexpensive one necessitated by an edict from DPP (NSF) banning descents into the main crater, where the existing microphone was installed (but not calibrated) last season. It was hoped that the old microphone would still work, and could be calibrated by comparison with the new one, because the crater is free from wind and many eruption sounds have been recorded there. Unfortunately, the cable down the crater wall had broken. The new temporary microphone is at the old Carbonaire battery site on the ridge between the Main and Side Crater, and will be replaced by a high quality one (courtesy of NSF) next season.
The New Zealand party also repaired the magnetic induction loop, and reburied most of the exposed sections which were at risk from weather and volcanic activity.
Telemetry recordings began from the summit seismometer on 24 December - from the infrasonic microphone (calibrated by raising and lowering it 3m at 5 second intervals to create a 24 Pa signal) on 26 December, and from the induction loop (calibrated by moving a set piece of the loop inside Erebus Hut through the geomagnetic field) on 29 December.
On 28 and 29 December following the arrival by helo of a Yamaha motor toboggan an electromagnetic (E-M) survey over about a quarter of the summit plateau was made using a portable 50m square loop, 24V battery, and reversing switch as the transmitter, and the induction loop around the crater as the receiver. Signals via the loops and also via VHF radio were recorded on separate channels of a tape-seismograph recorder, and contain data on possible presence of electrically conductive magma under the summit plateau.
Twelve stations were occupied in an area extending to 2/3 of the plateau radius and 1/3 of its circumference. Limitations were the E-M transmitter power (400 W) and VHF radio shadows. Between 24 and 30 December, another tape-seismograph recorder was used to record a Willmore Mk2 geophone (To = 3s, horizontal component transverse to the crater direction) sited 220m from the hut towards the crater and from 26 December the spare pressure sensitive microphone at the winch site was also recorded. A log of audio-visually observed eruptions was kept, but as the speaker in the hut was not hooked up to the microphone the log is not as complete as in previous years.
Readings of tiltmeter installed by Otway's party continued until 1 January 1983, and a beacon light was operated for Pat Tinnelly (L & S) to sight onto from Cape Royds. The New Zealand party descended on 4 January 1983.
The U.S. party collected lava bombs, installed aerosol collectors, and took a still and movie record of the lava lake and work in progress. Some of the film was shot for Science Express (NZTV). The Japanese party made a video tape of the crater and lava lake, and also a gravity survey of the summit area. They descended from Erebus on 27 December.
On 8 January, the new infrasonic microphone stopped working in a manner which suggested that it was producing a full scale DC signal. A helo flight was immediately requested, and thanks to the support of Dr. Kaminuma at McMurdo, Dibble, Bell and the Science Express camera crew got 2 hours on the summit on 11 January. The fault was traced to the pressure sensor, and the spare microphone was installed and calibrated. The only known defect in the summit installation was then in the geophone preamp/VCO (2380 Hz) which was converting the smooth changes in vibration amplitude into step changes (i.e. digitising it). Following the arrival of spare units from Alaska, McIntosh and Harrall (Sci. Lab technician for IMESS) flew to the summit on 27 January and replaced the faulty preamp/VCO with one on Hz. They descended believing that the installation was free of defects, but on 8 February the new unit went off frequency and then the transmitter went dead. The VXE-6 helo operations had ceased, and as only one member of the Survival School (Phil Austin) was available, no attempt was made to cure the fault. As at 28 February, the other 4 telemetry seismographs on Erebus are functional.
Transport to and from Antarctica was as follows:
No problems were experienced going to Antarctica. Returning to New Zealand proved difficult because resupply flights to Pole and Siple Stations had been delayed, and were first priority. Pressure for seats can be gauged from Dibble's experience. Although already delayed 2 weeks and in spite of priority assigned by the DOIC for family weddings beginning 12 January and preparation for the Pacific Science Conference beginning 1 February, he had to toss for the last of the 26 Kiwi seats available on the 8 January flight (and lost).
Helo transport to and from Erebus also proved difficult. On 30 November while still with K5, Dibble, Paintin requested a helo for a move to the Fang and were assigned 6 December as the earliest opportunity. On 3 December Dibble and Paintin returned to Scott Base in the surveyor's snotrac. From then until 17 December, the days we were on the helo schedule began cloudy (sometimes clearing later but Erebus was always scheduled for 9 a.m. and not rescheduled later) and on fine days we were not on the schedule. Flights up Erebus need to be on a weather-opportunity basis, but with many parties waiting for the helos, good lobbying at McMurdo was needed for this. Few of the helo crews had flown up Erebus before. The crew rostered to take us to Fang on 17 December declined, and we were fortunate that other crews volunteered.
On 17 December a US/Japan/NZ party of 7 flew to Fang, and otway's party of 3 descended to Scott Base 8 days after they had completed their work. On 18 December, W. McIntosh, J. Gamble and J. Berg reached the Fang on 3 Skidoos and on 19 December, McIntosh's party (and P. Kyle) reached the summit hut on 2 Skidoos (one got stuck in snow) only 3 days after leaving McMurdo, but they were unable to take any load above Fang, and were not properly acclimatised, so they returned to McMurdo next day.
On 21 December a helo came up empty to take the US/Japan/NZ party to the hut, and then brought L. Bell plus cargo up from Scott Base. On 22 December the remaining cargo was flown up. This included a Yamaha toboggan (350 c.c.) which was subsequently used during surveys of the summit plateau. It was not tuned for altitude, was hard to start, and lacked power at low speeds. It is garaged in the hut for the winter.
On 27 December, the US/Japan party descended to McMurdo by helo on a clear but humid day. During the first attempt to land contrails enveloped the helo and it had to circuit while the pad cleared. On take-off, contrails
The NZ party were scheduled to descend on 30 December and asked for an afternoon flight. Instead they were rescheduled for the next day which was unflyable. The next scheduling was 4 January which was cloudy but clearing at 0800. We suggested the helo wait until mid morning, but they came at 9 a.m. and could not land. The cloud cleared, as predicted and we were brought down by Lt. Turner in a perfect flight (with the helo absolutely full) at 1830 McMurdo time.
On 11 January, Dibble, Bell and the Science Express camera crew flew to the hut and returned to Scott Base 2 1/4 hours later.
To summarise, few delays were experienced when ground transport was used, even on Erebus, but Dibble and Paintin were delayed 19 days waiting for Helos up (14 days) and down (5 days) Erebus, and Dibble was delayed a further 4 days waiting for a flight back to New Zealand.
The weather on Erebus between 17 December and 4 January was generally fine with a marked absence of wind.
Instrumental observations reported on 0800 sked were:
Once at the summit, weather reporting (and radio skeds) were taken over by the field leader, Lindsay Bell.
K4 had a compak and two VHF radios. We suffered less from the poor ionospheric conditions and high noise level on the Scott Base receiver than other field parties, and were often called upon to relay messages. This rapidly exhausted the batteries of Otway's party, and they were incommunicado for about a week. Our party took more batteries and also a solar panel and American radio. The latter performed disappointingly, but the solar panel (with a 50 ohm resistor in series to limit the current) proved invaluable for recharging the 10 volt VHF batteries. Voltage had to be constantly monitored to prevent overcharging, and for safety an automatic regulator would be essential.
The VHF radios were invaluable for communication with Andrew Harrall in the science lab at Scott Base, and also between Erebus Hut and the E-M survey
Field preparation at Scott Base.
Pyne and McLeod arrived at Scott Base on October 11 to find that the seafloor sampling Wannigan had already been removed from its cantago sledge. The cantago sledge was required to move Vanda rebuilding materials to Marble Pt prior to its use by K5. This gave us the opportunity to properly repair the runners of the Wannigan which had been badly damaged by forklift during a previous season. Two new runners were bolted through the floor and wall plates, and the wall access holes patched afterwards. This work took Pyne and MacLeod two complete days and was one of many unanticipated jobs.
The Wannigan and sledge were again modified to suit new equipment and procedures. The winch required a new fastening system on the sledge, and enlarged wire access hole and new observation hole in the side of the Wannigan. This season we intended to sleep in tents while using the Wannigan to operate the coring, seismic and lab equipment and for water melting and cooking. The "range hood" was shifted from the side to the end of the Wannigan near the Colman heater and a new primus bench was built and installed underneath.
We were very pleased to find most of our cargo at Scott Base upon our arrival. The toboggans allocated to K5 arrived from Christchurch on October 16 together with our new winch. The next phase of our work programme which involved the testing and use of this equipment, included calibrating a special high accuracy "Halda twinmaster" odometer for the toboggan. The calibration was done over a one kilometre straight section of the ice runway access road which was considered an ideal surface. On this surface the odometer repeatedly measured within 5m of the taped one kilometre.
The tide gauge was set up off Scott Base for 13 days for testing prior to our departure to the field. The instrument worked well for five days until ice crystals which grew on the steel wire going to the seafloor froze the wire to the bottom of the DFA filled pipe and prevented accurate measurement. The wire line was later substituted for monofilament line which did not suffer the same freezing problem.
An ice reconnaissance flight by helo was arranged for October 21 (afternoon) for Pyne, McLeod (K5) and the two K26 surveyors. The helo flew to Butter Pt, mapping ice conditions enroute and circling Trig Herb to check that the drum beacon erected the previous season had survived the winter winds. On landing at the Butter Pt hut two further drum beacons stored from the previous season were filled with sea ice then underslung to Mt Coleman and Hjorth Hill where they were erected. This completed the beacon erection programme in the New Harbour area started late the previous season. While on Hjorth Hill the helo left to refuel at Marble Pt and returned as we completed the erection of that beacon.
Sea ice conditions were mapped along the coast from Cape Bernacchi to Cape Roberts. At Granite Harbour aerial photography of the Mackay Glacier tongue was attempted. Due to timing and altitude miscalculations the photographs did not provide the 40-60% overlap anticipated but gave good coverage. These photographs became invaluable in the field to help locate our sampling sites and lay out the movement monitoring poles. We were grateful that the Scott Base Information Officer found time to process and print the film and hope that an official system to rapidly process scientific photography at Scott Base be available in future years. After checking a surveying point at Cape Roberts the helo returned to McMurdo.
The sea ice reconnaissance gave extremely good information enabling us to decide on a route to Granite Harbour and for setting out the Butter Pt. seismic lines. Regretfully if more time were available it would have been well spent checking the extent of the ice crack off Cape Roberts.
A total of 18 days were spent at Scott Base preparing for the field. This period could have been shortened by a day or two if Macpherson and Paintain had not been required to sit exams in Antarctica as we felt obliged to let them use the evenings for study.
The drawing of explosives from the McMurdo magazine delayed us a further day. Late in the evening of October 31 after receiving the explosives we finally left Scott Base for Butter Pt., only 3 days behind schedule.
The travelling conditions on the sea ice to Butter Pt. were very good with the first significant rough ice encountered east of Butter Pt. This leg of the journey took 11 hours by D4. On the Bowers Piedmont at Butter Pt. a cache of our seismic equipment, seismic explosives, 7 × 44 gal DFA and 2 × 44 gal Mogas was left for our return in mid-November. The east-west seismic line was located and bulldozed and three sea ice movement survey beacons established during the next three days. Pat Tinnely (K26 surveyor) joined K5 from Vanda during this period and was responsible for surveying.
The next leg from Butter Pt to Cape Roberts took a total of 16 hours and was broken into two days. Rough ice extending east of Butter Pt to Cape Bernacchi was avoided by travelling east along our seismic line then towards Marble Pt., along the American fuel train road. Travelling conditions from Marble Pt. to Cape Roberts were very good about three kilometres off the coast. Rough ice extended along the coast eastwards of our route coming in close to the coast at Cape Roberts but was easily negotiated.
Two days were spent camped at Cape Roberts while we began bulldozing a seismic road due east from Cape Roberts. An active ice crack was encountered 3km out which was impassable by D4 and caused the planned sea ice based seismic programme in this area to be abandoned. Ice thickness at the crack was measured
The sea ice conditions in Granite Harbour provided good travelling. Snow cover was minimal on the first year ice which penetrated to the front of the Mackay Glacier. Second year and multiyear ice was encountered westwards of the glacier snout. The second year ice was extremely hard with a scalloped surface except on the abundant frozen meltpools. This ice required a considerable reduction in travelling speed for comfortable riding.
The period 9-17 November was spent working in Granite Harbour with our base camp near the glacier tongue. The first part of our programme was to begin a movement survey of the tongue. Two sets of poles were put in on the tongue and surveying control was established on the Flatiron and on the ridge west of Cuff Cape. The New Glacier was used as a toboggan route to get people and surveying equipment to the Flatiron and Cuff Cape. Some difficulties were encountered on the bare ice at the snout of this glacier. Minor crevasses at the steeper top of the glacier were easily crossed. This part of the programme took longer than expected because new survey control was required and the initial difficulties of walking on the abundantly crevassed Mackay Glacier tongue. At the end of this part of the programme the surveyors (K26) left us by snotrac, checking the tide gauge at Cape Roberts for its continuing operation enroute to Butter Pt.
During the remainder of the time at Granite Harbour two good seafloor cores were taken within a large accessible sea ice filled crack in the tongue and at the front of the glacier. Current measurements were made and bathymetry measurements attempted. An electronic problem with the newly acquired echo sounder resulted in few successful measurements but this problem was fixed later in the season at the Blue Glacier. The weather was extremely good at Granite Harbour during this time and no days were lost due to adverse weather.
The seismic programme required us to leave for Butter Pt. on November 18 reluctantly bringing to an end the oceanographic work in Granite Harbour.
The journey from Cape Roberts to the Butter Pt. seismic line took 15.5 hours. Two days were spent awaiting the arrival of Ray Dibble and part of the seismic line was reflagged in poor weather during this time. K26 joined us to resurvey the sea ice beacons on November 27.
The seismic programme at Butter Pt. was completed on November 28 when we moved to the Dailey Islands, meeting the Geophysics Division party led by Tim Stern (K7) and continued a seismic programme in this area. The journey took 8 hours by D4 and of this about 1 hour was spent extracting an obstinate cantago sledge from a recently formed 1.5m wide ice crack trending east from Butter Pt. The sledge was extracted without much difficulty and was at no time in danger of losing its load. A further to wide crack trending eastwards from the Stranded Moraines was easily crossed.
The seismic programme at the Dailey Islands was completed on December 3. K7 and Dibble/Paintin returned to Scott Base. The next day while the remainder of K5 moved to the front of the Blue Glacier. A good seafloor core was obtained about 200m off the glacier front. We were joined by the Scott Base mechanics/science technician for a night while they replaced the engine on one of the Snotric toboggans, and examined the echo sounder.
The period December 7-9 was spent making bathymetry measurements from the Blue Glacier to Cape Chocolate, Cape Chocolate to Dailey Islands. Bathymetry measurements were also made at the shot points along the Dailey Islands seismic lines and along the McMurdo Ice Shelf front. A coring attempt near the Dailey Islands was only partially successful because of the compact sandy bottom.
K5 returned with the D4 to Scott Base on December 10.
Repairs were made to the toboggans enabling Macpherson and McLeod to set out for Explorers Cove in New Harbour 2 days later. At Explorers Cove they met the K26 surveyors and then moved to Butter Pt. to complete the final surveying of the sea ice movement beacons for this season. 3 days were lost owing to adverse weather. The Dailey Islands seismic lines were also surveyed before returning to Scott Base.
The "clean up operation" and return of equipment took just over a week. The sampling equipment required for the "Glacier operation" was prepared in readiness for February and left at Scott Base. Some minor damaged parts were returned to New Zealand for repair. During this period Pyne and Brian Smith set a series of explosions at the ice runway for K11. The explosions were intended to produce gravity waves which were recorded by K11 on the ice runway monitoring strain network. Bathymetry measurements were also made off Scott Base on a line to Mt Heine. The line extended 3km until depths greater than 560m could not be resolved.
During the period on the sea ice garbage was burned and the cans crushed by D4, bagged and returned to Scott Base for disposal. Human waste was deposited in augered holes in the sea ice.
Explosives were drawn by K5 from both U.S. and N.Z. stock held in the McMurdo Station magazines, and controlled by the U.S. Navy. The explosives were used mainly for seismic shooting although a small quantity was required to remove a large pressure ridge on the west/east trending Butter Pt. seismic line and for Robin Holdsworth at the ice runway.
This season for the sea ice work K5 was allocated the D4 bulldozer which towed 2 "cantago" sledges (carrying Wannigan, equipment and fuel). 2 Snotric toboggans 037 and 036 (later replaced by 039) and two Tamworth sledges.
The D4 was initially used this season for the fuel train and Vanda resupply to Marble Pt, and developed a fuel tank leak during this time. After returning to Scott Base the fuel tank was repaired, and the D4 given a general check and oil change by the Army Plant Operators and Malcolm McLeod before it was used by K5.
The only major problem with the D4 was the recurrence of the fuel tank leak in Granite Harbour. An attempt to replace the tank with a 44 gallon drum was not completely successful as vibration eventually sheared off the drum fittings and we reverted to the original tank. Over 4 gal/8 hours of DFA was collected from the leaking tank, while the D4 was stationary and idling. This contaminated fuel was used in the Wannigan heater.
The D4 was kept idling overnight and was only turned off intermittently during seismic recording. Average fuel and oil consumption for the field period is listed below:
SM 037. This toboggan gave few problems in the field. Four bogey springs were replaced during normal use. A complete bogey assembly was damaged when the allen cap screw came out of the bogey axle. This was attributed to a
The toboggan had a partial dunking in a frozen tide crack near the Mackay Glacier Tongue. Salt water entered the gear-box but was quickly removed by three successive oil changes and no starting problems occurred.
SM 036 was used for 3.5 weeks during which time only 4 bogey springs were replaced. While returning to camp down the New Glacier, the steering shaft sheared off where it attaches to the front ski. The remaining 7km to camp was negotiated with a person sitting on the front and steering with a length of rope and his feet. This toboggan was airlifted to Scott Base and replaced by SM 039.
SM 039 was airlifted from the lower Victoria Glacier, where it had been used by K1, to our camp in Granite Harbour. When it arrived we found the rubber sprockets on the right rear axle to be badly damaged and replaced the complete axle with our only spare. This machine was burning over 1/2 litre of oil per day unlike SM 037 and SM 036 which required only a small top up each week.
The engine on this machine "blew up" while carrying out critical seismic shots off Butter Pt. Piston, con rod and bearing were fragmented into several pieces. The engine was replaced with a new engine by the Scott Base mechanics while at the Blue Glacier five days later. The steering shaft also broke on 039 in the same manner as 036. On this occasion it occurred at a less critical time on flat sea ice one day before our scheduled return to Scott Base.
The distances travelled with each toboggan are listed below:
This is the second season that Cantago sledges have been used on sea ice. On hard multiyear ice and bare firstyear ice the sledges tended to crab sideways which was partly due to a bent and therefore off-centre draw bar. The absence of any chain tensioning devices meant that this could not be corrected in the field. It became evident that loading is crucial to the sledges' performance because of the flexible deck but unfortunately it is not always possible to redistribute the loads daily. Modification of the skis to increase the surface area and rocker forward and aft is still necessary for rough ice and soft snow. Without these sledges however it would not have been possible to carry out our successful sea ice programme of the last two seasons.
The Tamworth sledges towed by toboggans were used to ferry our heavy sampling equipment on the sea ice near the Mackay Glacier Tongue and people on New Glacier. The older sledge fitted with keels was easily controlled and used on New Glacier requiring rope brakes only on parts of the downward journey. A new sledge without keels was extremely difficult to control fishtailing badly on sea ice. All the laminated bridges along the left side were cracked after work in Granite Harbour although the sledge was never rolled with a load on. How this occurred is still puzzling but it is most likely that a sideswipe with a heavy load (800 lb) may have caused the cracks. A new type of longer keel should be considered for Tamworth sledges which permanently protrudes under the ski and does not require a slot cut in the ski like the present adjustable keels.
All 7 allocated helo hours were used this season. The sea ice reconnaissance to Granite Harbour and erecting beacons in New Harbour used 4.5 hours flying time and 1.5 hours ground time. The remaining 2.5 hours was used transferring 036 and 039 toboggans and flying urgently needed parts and surveyor to Granite Harbour.
Good weather conditions dominated our field season on the sea ice particularly in Granite Harbour which appears to be sheltered from the McMurdo Sound southerly winds and snow. Only 5 days in total were unworkable all in the vicinity of Butter Pt. strong winds and blowing snow disrupted seismic work on two separate days (late November) and three days were unsuitable for surveying in mid-December.
The VUW seismic party had 3 Compak radios with spare aerials and 5 spare batteries. Communication along the seismic lines on 4703 kHz was excellent
Communications with Scott Base were generally good although long scheds were sometimes a nuisance if we had messages to pass and were also awaiting seismic shots.
We were again unfortunate not to be allocated VHF radios for our scientific work especially when surveying on the Mackay Glacier tongue. Mirrors can be used for very simple messages but they just do not work on cloudy days.
A photographic service (person and facilities) at Scott Base could be of considerable use for some scientific field parties. If a person at Scott Base were available to develop and print photographs many scientists could take photographs by helo on field party put-ins expecting prints to be available to work from a few days later in the field. Such a service would be useful for geology field mapping (where available aerial photography is unsuitable), surveying especially in the case of mobile features which change each year, e.g. calving ice tongues, and biological studies, e.g. seal and penguin census. The information officer might be a suitable person to provide this service. However, it would have to be recognised as part of his duties.
A Scott Base explosives facility is becoming important as more field parties require explosives for their work. Two distinct problems are obvious:
This season it was very disappointing to find much of the packaged dehydrated meals to be of lower standard than normal. It would appear to have been a bad batch and often was only suitable to make soup. The only field situations where "dehy" is essential is mid-summer in the dry valleys where temperatures are well above 0°C and where weight is vital, such as backpacking. Even on the sea ice in mid-December frozen meat can be kept below 0°C by adding snow/ice to a food box (fridge). I would like to see a change from the present "dehy" meals to an easier access to frozen meat for field parties requiring it and modern N.Z. "freeze-dried" meals for the rarer special situations.
In December, tents, mattresses and sleeping bags often get very wet and salty when camping on bare sea ice making life miserable. Low camp stretchers that fit in a polar tent would prevent this and would be less bulky than the present foam mattresses. Waterproofing the present foam mattresses and PVC groundsheets may be a cheaper alternative.
The VUWAE programme for GLACIER CRUISE IV had three main aims:
An outline of the proposed programme was submitted to RDRC in September 1981, and a more detailed cruise plan passed to Antarctic Division in July 1982. A revised programme was drawn up at Scott Base in the days before the cruise, after consulting with Dr. Mabin, University of Auckland, who had travelled down on the ship. The ultimate success of the cruise for VUWAE was in no small measure due to discussions with Dr. Mabin, who prepared us well to use fully the potential of the ship.
Barrett, Macpherson and Pyne flew to Scott Base on February 4 to find that the cruise had been delayed until February 12. Three days were spent organising a University store in the hangar, and the rest of the time planning and checking equipment sent down earlier. A meeting of all cruise participants was held at the NSF chalet on February 6; and included a 6-man USARP team of biologists to carry out midwater trawling, Dr. Mabin to look at beaches, and Messrs. Mitchell and Hunt from NZ Oceanographic Institute to sample the upper 200m of the water column. The biologists had to leave the ship about February 15, so we agreed their programme should have priority for that period, with Dr. Robinson as Chief Scientist. Dr. Barrett was named Chief Scientist for the second part of the cruise.
On February 12 Dr. Barrett arranged to go on board early to talk with Dr. Anderson, Rice University, who was a scientist on Cruise III. This was extremely useful in finding out how to work in with "the bridge" so that station time was minimised. We also learnt of Dr. Demaster's programme to determine sedimentation rates from radiometric dating, and of Dr. Dunbar's study of modern sedimentation using sediment traps. We took up the offer of his last undeployed trap and later successfully set it in 800m of water in Granite Harbour.
The ship departed McMurdo at 1700 on February 12 and we occupied two stations for grab samples while the biologists were organising their equipment. During this time we came to terms with the satellite navigation system, and the fact that there was no automatic system for recording the ship's position. During the first part of the cruise we persuaded the quartermaster on duty to mark the position on the depth recorder chart every 30 minutes, but realised that this was insufficient for good navigational control. For the second part
Sampling strategy was to use first the grab to take a bulk sample and determine seafloor character, for if there were many stones the sphincter corer could be damaged. Stations 1 and 2 were gravelly and no core was attempted. The next twelve hours were committed to trawling up and down Bird Basin, which brought us on to Station 3 at about 1500 on February 13. At Station 3 the wind and drift rate were high. The grab was successful with few stones but with the high wind (30 knts) and drift we decided to forego our first sphincter core attempt. The ship then trawled to Station 5, another deep water site just east of the northern tip of Ross Island, where both grab and sphincter cores were successful, though the corer had penetrated only 10cm. At the next station (6) the grab was successful but the trigger on the corer did not release. This was the pattern at the next 3 sites (Stations 8, 7 and 4), despite several hours of thought and effort in the ship's engineering shop. By the end of the first part of the cruise, however, modifications had been completed which we were fairly sure would work and in fact this proved to be so. Evidently, the fine tolerances in the trigger mechanism that were quite satisfactory for coring from a stable sea ice platform, were unsatisfactory for a shipboard operation where the platform was rolling and heaving. The failure to collect good quality cores with the water-sediment interface preserved was to some degree mitigated by the excellent grab recovery, which yielded in most cases chunks of the seafloor to a depth of 15cm with the surface identifiable and more or less intact.
The second part of the cruise, with its main objective Granite Harbour, began near midnight on February 15. After a grab in 620m of water off Scott Base (Station 26), we followed the edge of the McMurdo Ice Shelf to within 2km of the Victoria Land coast and took 3 grab samples, all sand with varying amounts of gravel. We then headed north for Granite Harbour, making a slight detour to core near station 3. This was also the first opportunity to test the corer, which to our great relief, worked well.
The cruise track to Granite Harbour took us to a point east of Cape Roberts before heading on to Cape Archer. On the way north Messrs. Pyne and Macpherson carried out a sea ice reconnaissance of Granite Harbour by helo. They found it virtually ice-free, and we immediately worked to change our plans to take advantage of this. We decided firstly to carry out a bathymetric survey and then to sample on the basis of the new bathymetric data. Nevertheless, we did not expect to change our distribution of stations much, apart from moving them further into the Harbour.
The bathymetric survey took less than twenty hours, and revealed a rather less regular bottom topography than expected. During this period Pyne and Macpherson with helo support put in place a sediment trap on the seafloor at the tip of the Mackay Glacier Tongue for recovery next season. The first attempt by Zodiac failed because of carburettor icing.
The day following the bathymetric survey was spent sampling and yielded 6 grab samples and three sphincter cores, all 50 to 60cm long. Our only problem was in getting the ship into the right position, taking into account drift, so that the ship was over the right spot when the sampler reached the seafloor (20 minutes or up to 1km after the ship was stopped and due to the time required to lower the sampler). This was most difficult in sampling the west-facing scarp off the Harbour entrance (Station 11) but also delayed us at Station 16, where the deepest part of the Harbour was cored.
During the later part of the sampling programme, it became clear that the ship would be required at McMurdo Station early on February 19 for the departure of the "Southern cross", though the cruise had been planned through to February 20. We therefore had no time to obtain the sphincter cores from Bird Basin, and instead plotted a track back across the Western Shelf that would give useful bathymetric data and also accurately locate a deep narrow valley off Butter Point. During the survey, samples and equipment were packed for transit to Wellington. The survey used up all of the remaining 12 hours of ship time and we arrived off Hut Point at 0730, February 19.
Transport to and from Antarctica was by C-130 Hercules. However, the programme was carried out aboard the "Glacier", except that helos were used from the ship on two occasions (for ice surveillance and to set the sediment trap) and a Zodiac was used once (unsuccessfully).
The major difference between shipboard work and our traditional sea ice operation was in getting used to having so much assistance and so little time to think. We were fortunate in the first part of the cruise to share the ship with a team of USARP biologists so that we could work out a satisfactory scheme for recording navigation and find out the strengths and constraints of shipboard operation. McMurdo Sound is a small area for a ship that can, and on occasions did, steam at 12 knots. Also our team of three was small for an operation to utilise the ship fully 24 hours a day.
The chief problem was with navigation, as the printer for NAVSAT data was not working, and the data had to be recorded by hand. Also, because the ship's speed was manually entered into the system, the ship's location between fixes (which were obtained hourly on average) is subject to some error, but this will be reduced as we work on the track of the cruise with information from the ship's log. Nevertheless, these difficulties were far outweighed by the advantages of shipboard work which included:
The weather during our period at sea was overcast in the Sound, with winds up to 30 knts from the southeast in the first 2 days. In contrast, Granite Harbour most of the time had less than 4/8 cloud, and little wind.
Our orange peel grab generally performed well in sediment ranging from soft mud to a coarse gravel. However, it did not trigger on several occasions for one of two reasons, insufficient line out (with a strong drift we found it necessary to pay out as much as 1100m of wire to reach bottom in 800m of water), or the release hook jammed in a shackle. Both problems were easily overcome once identified. The trigger mechanism on the sphincter corer also gave trouble, and required several attempts before it was modified to work satisfactorily. Nevertheless, it worked extremely well for the second part of the cruise.
The hydrographic winches on "Glacier" were ideally suited to our work. Continuous display of wire speed and load was particularly useful, as we soon found the optimal working speeds for each piece of equipment. The grab could be sent down at 80m/minute but if it came up much faster than 25m/minute the sample was washed. The sphincter corer could go down at 80 speeding up to 150m/ minute over the lower 70m, then up at 60. Faster retrieval risked the butterfly valve and the core. Operating speeds were important to establish not only for the most satisfactory operation of the equipment, but also because the engine room required 30 minutes notice to provide power for the ship to get underway.
Geological studies of the Triassic part of the Beacon Supergroup were conducted by postgraduate students from Victoria university. The party consisted of Barry Walker, event leader, PhD student, geology, Isobel Gabites, MSc student, Palaeobotany, and Mike Hosted, DSIR field assistant.
Sixty-four days were spent camped on four mountains situated on the edge of the polar plateau, of these twenty-eight days were at Mt Bastion, seventeen at Portal Mt, eleven at Shapeless Mt and eight at Allan Hills. Adverse weather conditions at Portal Mountain and shapeless Mountain this year delayed helicopter movements by up to nine days. Overall 21 days (32% of the time in the field) were 24 hour "tent days". 38 days (59%) were work days and of this number several were only 1 to 3 hours long due to poor weather. The remaining 5 days (8%) were spent waiting for helicopters.
A scheduled move on December 7 from Portal Mountain to Shapeless Mountain was postponed due to VIP and DV helicopter commitments. During the following 9 days, the party was confined to the tent as we experienced gale force and stronger winds, blowing snow, white out conditions and −20°C temperatures. It was during this time that the party suffered mild carbon monoxide poisoning from the primus stoves. Our freedom of movement was considerably hindered during the next few days. During the last 3 days at Portal Mountain communication with Scott Base was confined to Yes/No morse key operation after our last battery became flat after only 5 days operation.
December 16 to December 27 was spent at Shapeless Mountain. During the last 6 days, heavy snow falls from the north completely covered all rock exposure and this still appeared to be the situation when flying past on January 5. A rapidly fluctuating low cloud cover frequently reduced visibility to under 1 kilometre. At the same time the dry valley regions and other mountains of similar altitude were experiencing relatively fine conditions. Following later talks with helicopter pilots it became apparent that Shapeless Mountain is at times prone to accumulating a local cloud cover capable of preventing helicopter entry.
At Mount Bastion and Allan Hills work days greatly outnumbered tent days and considerable scientific work was achieved. As temperatures warm later in the season Mount Bastion is commonly covered in thick snow and the relatively sheltered nature of the mountain hinders a quick clearance. Weather conditions at Allan Hills appeared to be consistently better than the dry valley region.
Radio batteries remained good for an average of only 10 days with one lasting 5 days. Radio signal strength from Scott Base was good. However, our signal was poor and no direct communication with Scott Base was possible once leaving Mount Bastion (November 29). Signal strength both to and from Vanda Station was nearly always good.
The North Face Dome Tent proved to be excellent and its lightness enabled an important extra camp to be put in by foot at Allan Hills.
No difficulty in movement in the field was encountered at any of the areas visited.
Overall, despite the season at times being difficult, all objectives were achieved.
Korsch and Napp arrived at Scott Base on November 14, one day behind schedule because of a turnaround by the C130. The next two days were spent on the Survival Course and organising field equipment and on November 17 we were transported to the Miers valley by helicopter. We "camped" in the Wannigan at the western end of Lake Miers which we found very comfortable compared with a polar tent. Over the next few days we carried out a reconnaissance geological survey, concentrating on the divide between the Marshall and Miers valleys and then the south wall of the Miers Valley. On one occasion when the winds started suddenly we were on an exposed part near the summit of the ridge and Korsch suffered a case of frost nip on the nose.
On November 19 we observed three dead seals approximately 400m above the valley floor on the north wall of the Miers Valley. They were about 100m apart on a steep talus slope consisting of jagged blocks up to 30cm in diameter, and were in various states of preservation. The youngest carcass had been there for a very short time, probably less than a season, because frozen blood had not yet been wind abraded.
Korsch and Napp were relocated to Shapeless Mountain on November 23 by helicopter which then transferred Hosted from K6A at Mt Bastion to K6B. After setting up camp in a small basin approximately 2 1/2km ENE of the summit of Shapeless Mountain we did a reconnaissance trip to the summit of the mountain. In the cold windy conditions Korsch suffered a second case of frost nip but after this Hosted made "Lone Ranger" masks out of leather to protect our noses, and these proved to be very effective in cold, windy conditions.
The first two field days at Shapeless Mountain were spent on reconnaissance surveys and then the rest of the field work was oriented towards detailed data and sample collection.
Our major handicap at Shapeless Mountain was the loss of work time due to strong winds, and although we worked whenever possible, sometimes in marginal conditions, we still lost approximately half our field days.
On November 27 K3 (coal geology) party arrived at Shapeless Mountain and camped approximately 3km from our site. When they departed on December 2 we were able to obtain a fully charged battery for the Compak radio from them to supplement our batteries.
On December 1 about 1km NE of the summit we observed a snow petrel in flight and on December 9 while at the western extremity of Shapeless Mountain we observed two snow petrels in flight.
HRH Prince Edward during his visit to Antarctica was scheduled to visit K6B as well as other Kiwi field parties on December 10, and hence we remained at camp for the whole day while weather conditions were good. The helicopter finally flew overhead just after 9 p.m. but was unable to land as the weather conditions had changed and the wind increased to strong gusts. Had we been informed on the morning radio sked of the expected arrival time of the royal party we could have utilised the good weather for field work.
Although we concentrated our field work on the rocks exposed at Shapeless Mountain we visited Mistake Peak on December 12 and found a similar geological situation there as to that on Shapeless Mountain.
After an extended stay on Portal Mountain K6A (Walker and Gabites) were finally relocated to Shapeless Mountain on December 16. Bad weather on the polar plateau side of the mountain meant they were unable to land at the site they had chosen and hence they joined us at our campsite. Highlight of the reunion was the birthday party for Isobel Gabites, celebrated with the resupply sent from Scott Base and for which we were very grateful.
Our relocation from Shapeless Mountain to the Allan Hills originally scheduled for December 13, was delayed for a few days and rescheduled for December 18. Bad weather in the Allan Hills region forced a postponement and on December 20 Korsch and Napp were transported to Scott Base by helicopter, the Allan Hills segment being cancelled due to lack of time.
At Scott Base we cleaned our field gear, packed rocks and equipment for shipment back to New Zealand and commenced report writing, eventually leaving Antarctica on January 2 arriving in Christchurch and then Wellington on January 3.
In the field all garbage was stored in plastic garbage bags and returned to Scott Base where it was sorted into combustible and non-combustible items. Plastic garbage bags were used for our campsite toilet and the excreta was also transported back to Scott Base.
Apart from minor problems outlined elsewhere the field season was extremely successful with the major aims being accomplished. This could not have been done without the support from the staff of Scott Base.
Excellent weather conditions were experienced early in the season, both in the Miers Valley and during the first ten days at Shapeless Mountain. However, out of the last 17 days on Shapeless Mountain we had suitable working weather on only four (4) days. The major factor was the wind which blew consistently at 20-30 knots with gusts to over 70 knots, coupled with temperatures
A Compak radio was provided for the twice daily radio skeds with Scott Base. We found that we always needed to transmit on high power and that the batteries had a life of only 8-10 days. Communication with Scott Base was often very difficult due to ionospheric disturbances, and a lot of skeds had to be relayed via Vanda Station or another field party. On the positive side it was only in extremely rare cases that we were unable to receive transmissions from Scott Base.
One problem we experienced in the field was that although we had provided a "shopping list" during the radio skeds, the items and our mail were not put on helicopters coming to Shapeless Mountain although there were at least 3 opportunities when this could have been done. The problem continued after we left the field as mail for K6A was not forwarded during their relocation from Shapeless Mountain to the Allan Hills. Information regarding possible helicopter moves was often patchy and when helicopters did not arrive when scheduled explanations via the radio were rarely given.
All transport in the field was by helicopter with the put in to the Miers Valley being on schedule. The relocation to Shapeless Mountain was one day late due to bad weather. The planned relocation from Shapeless Mountain to the Allan Hills was delayed for seven days due to several factors including the visit to Scott Base of HRH Prince Edward, bad weather and a backlog of helicopter requirements. Consequently, this part of our scientific programme had to be cancelled and we returned to Scott Base on the originally scheduled date.
The nature of the project at Shapeless Mountain required visiting all parts of the mountain and this often meant walking up to six hours a day. It was originally intended that K6A would camp on the opposite side of the mountain so that we could use their camp as a "resting point". However, they were delayed at Portal Mountain for nine days for the same reasons as our delay at Shapeless Mountain and when they eventually were moved to Shapeless Mountain bad weather forced them to camp with us.
A further problem was the lack of Hercules flights from McMurdo to Christchurch prior to Christmas and we had to spend 14 days at Scott Base waiting to be transported to Christchurch.
We were impressed with the quality of the clothing, the only exception being the woolen finger gloves. Due to collecting and packing rocks,
During one particularly bad spell of weather the "North Face" dome tent periodically collapsed in the gale-force winds as the flexible metal poles bent inwards. When the wind slackened it would "pop" out again. During this time the polar tent was very stable in the wind.
Minor damage to the dome tent occurred on December 7 and on December 19 and although the tent was easily repaired in the field it was not as well suited to the high winds as was the polar tent.
The only loss of equipment was one bush shirt, two pairs of socks and a geological hammer. These were sent in a cargon from Wellington to Scott Base but could not be found on arrival at Scott Base although most of the equipment sent in the same cargon did arrive safely.
We wish to thank the University Grants Committee and the VUW Internal Research Committee for financial support, to Antarctic Division, DSIR, for logistic and field support, and to the U.S. National Science Foundation for helicopter and shipboard support.
Practical assistance at VUW came from Ernie Millington and his team in the Engineering Workshop, especially Graham Hewitt, who overhauled the tide gauge recording mechanism, from Colin Heath, Electronics Facility, from Professor Christoffel and Eric Broughton, Physics Department, and Bill McQueen, Master of the "Tirohia"
In Antarctica this season we were grateful to all Scott Base staff, but especially John Thurston (leader), Kerry Kirkness and his mechanic assistants and Doug Martin (science technician). In the field we were ably assisted by Malcolm McLeod, Mike Hosted and Lindsay Bell. The work of Pat Tinnely and Tony Hawke, Department of Lands and Survey, was also appreciated.
Finally, we are grateful for the efforts of Antarctic Division toward securing us time on the GLACIER. We are especially appreciative of the excellent support and co-operation from Captain Taylor, his officers and crew. Their willingness to work near shore in uncharted waters and to respond positively to a programme that at times changed rapidly and radically was essential to the success of the cruise.
VUWAE programmes have become more sophisticated in recent years requiring considerably more equipment and our cargo to Antarctica is likely to increase as this trend in programmes continues. Much of the sophisticated equipment we use have dual roles both in Antarctica and New Zealand and thus cannot be left in Antarctica during the winter. Modifications to equipment also require the equipment to be returned to New Zealand. As suitable secure winter storage becomes available at Scott Base we will continue to look closely at which equipment can remain.
The schedule shows that although progress was nearly twice as fast with 2 parties rather than one, both survey procedures were efficient, and not critically dependent on the weather. Good records could be obtained with small shots even in blowing snow conditions.