K047: Petrology of Sirius Tillite Antarctica New Zealand 1996/97
Antarctica New Zealand November 1996 - December 1997
The main goal of the project is to understand the Sirius Group tillite in the Dry Valleys area. The significance of this deposit centres on an intense international debate concerning the extent of the East Antarctic ice sheet three million years ago. The dynamic view in the debate favours a nearly complete deglaciation, while the stabilist view favours an ice sheet which formed nearly 14 million years ago and retained its shape through until the present day.
The aims of the field work, as established by the PGSF grant in December 1995, were to collect data for a geologic and geomorphic map of the Sirius Group at Table Mt and Mt Feather. Cores at least one metre long of the Sirius Group outcrops were to be obtained from at least three sites each at Table Mt and Mt Feather. Coring locations were to be selected on the basis of geomorphic mapping and previous sites where study samples were taken.
The achievements of the November - December 1996 field season were significantly greater than the initial goals of the project established in December 1995. Over the 23 field days, enough geologic and geomorphic data were collected to provide a detailed map of about four square kilometres on the northwest flank of Table Mt. Detailed glacial fabric analyses of the Sirius were made at 12 sites. Hand-held aerial photographs were taken of the area from an altitude of about 3000 metres. Included in the photographs were four GPS positions, accurately surveyed to within 0.5 metres with reference to the Table Mt trig.
A total of about 49 metres was drilled at seven locations on Table Mt. Of this, about 42 metres of core was collected, giving an average recovery rate of 87%. On average, the core holes were 3.5 metres deep, but two of those reached a depth of 9.5 and 8 metres. The significant amount of ice in the pores and fractures of the core was a surprise. The age and origin of this ice is open to much speculation and research.
Ground temperatures from the surface to a depth of 3.5 metres were measured in four holes. Measurements were taken at 25 cm spacings down the hole. These were taken for a duration of five days at one hole but for only one to two days at the other holes.
A full camp move to Mt Feather was not made due to the condition of the drilling equipment and high risk of minimal core recovery. Instead, we made a reconnaissance of Mt Feather with a light amount of drilling equipment. With a helicopter standing-by, two holes were drilled to a depth of 0.8 and 0.4 metres. This drilling established that the coring characteristics of the Sirius at Mt Feather were similar to those at Table Mt. We also established that the success of coring depends largely on the use of compressed air as a cooling and flushing medium for drilling these types of ice-cemented glacial deposits. Prior to leaving Table Mt, a reconnaissance was made for Sirius deposits at the same elevation as Table Mt and directly across the Ferrar Glacier on Knobhead. Outcrops of Sirius were not found, but the soil regolith on Knobhead was identical to that on Table Mt suggesting that Sirius may have also been deposited on Knobhead.
|Warren Dickinson 101 Beauchamp St Karori, Wellington||Event leader/coordinator, responsible for overseeing and assisting with all of the duties performed by event personnel|
|Jon DeVries 62 Buckley Rd Melrose, Wellington||Field leader, mountaineer, safety officer, loadmaster, mechanic|
|James Goff School of Earth Science Victoria University PO Box 600 Wellington||Site geologist, geologic/geomorphic mapping, assisting with coring, core analysis; provide compiled base maps for field mapping|
|Ian Jennings School of Earth Science Victoria University PO Box 600 Wellington||Mapping and measuring of field data, logging/packing/processing of core, core analysis|
|Pat Cooper Cooper Drilling Services Rapid Creek Waimangaroa, Westport||Driller and mechanic|
|Bain Webster Webster Drilling PO Box 50-354 Porirua||Drilling contractor and designer of drilling equipment|
3 Event Diary (Nov - Dec 1996)
|Nov 14||Dickinson, Goff, Jennings, and Webster depart (13:00) Wellington for Christchurch; fitting of field clothing; night at Windsor|
|Nov 15||Christchurch to Scott Base (Dickinson, Goff, DeVries, Webster, Jennings)|
|Nov 16-18||Antarctic Field Training (Dickinson, Goff, Jennings, DeVries-assistant instructor); Webster unpacking and setting up drilling equipment|
|Nov 19-21||Tested drill equipment on permafrosted ground at Scott Base and on sea ice; Dickinson and Webster packing and testing drill equipment for field; DeVries, Jennings and Goff packing food, and field equipment. Webster returns to Wellington Thur, 21 Nov.|
|Nov 22-24||All equipment staged into four loads on helio pad. Dickinson, Goff, Jennings, DeVries, R & R Scott Base|
|Nov 25||Goff and DeVries depart for Table Mt 10:00 from McMurdo; Dickinson and Jennings depart for Table Mt 14:30 from McMurdo arrive at Table 15:30.|
|Nov 26-27||Set-up and establish camp; reconnaissance of area, drill site selection; start geologic and geomorphic mappingpage break|
|Nov 28||Cooper arrives with load #2 at Table Mt; final load #4 arrives at 16:30. Sent back rock for Thornley memorial and Nerida Bleakley's samples from Dec 1994. Set-up kero heater in Pol-haven tent. Set up drill rig after dinner.|
|Nov 29||Set-up and drilling by 12:30 and first metre is very slow. Become stuck in hole at 17:30p, break for dinner to make plans.|
|Nov 30||Whole day spent trying to recover frozen bit; recovered core barrel drill rod but unsuccessful with bit and reamer and decided to continue with productive drilling.|
|Dec 1||Recovered 6.05m (nearly 100%) at site TM-1C.|
|Dec 2||Requested 9m of NQ drill rod from Cape Roberts Project so we can reach bedrock contact. Did not have more pipe because did not expect to be able to drill this deep.|
|Dec 3||Decision made to not take camp to Mt Feather. Equipment is stressed and time would be better spent doing complete job at Table. However, a reconnaissance with light drilling equipment should be made to Mt Feather.|
|Dec 4||Helio arrives 13:30 with additional pipe and Terralink crew (Belgrave, Cairns, and Simonson) run GPS survey and photograph NW Table Mt area.|
|Dec 5||TD hole TM-1C at 7.29m in bedrock. Sledge compressor down hill to site TM-6.|
|Dec 6||Site move to TM-7 using helio to carry compressor.|
|Dec 7-9||Drilling slow due to many repairs and complications in drilling unfrozen clast-rich material near the surface.|
|Dec 10||Resupply helio due to arrive at 14:00 but delayed by mechanical problems. The NSF, Bell 212 arrives 20:30, and Dickinson, DeVries, & Cooper travel to Mt Feather for reconnaissance and test coring; Return Table Mt at 01:00 (Dec 11) to pick up Terralink GPS; Goff returns (01:30) to Scott Base for treatment of eye injury.|
|Dec 11||Late start! Move core box to upper helio pad. Start drilling of TM-8B. Early dinner as three of us are still quite tired.|
|Dec 12||BBC (Kate O'Sullivan) arrives unannounced 09:00 to film. TD hole TM-8B at 5.9m in hard dolerite clast; much core loss in this hole due to gravels.|
|Dec 13||Reach 9.52m in TM-7B without penetrating bedrock contact, but equipment won't allow deeper drilling.|
|Dec 14||Goff arrives back at Table Mt; Jennings and Goff reconnaissance of Knobhead; Cooper and load #1 of drilling equipment return to Scott Base|
|Dec 15||Continue temperature measurements, Goff and Jennings recon south end of Table Mt and in the afternoon recon they recon to the north. We all fill in Prentice trench dug in 1993 to look at Sirius. Light snow in late afternoon.|
|Dec 16||Continued temperature measurements, clean up of drill sites and reclamation of tracks with rake and broom. Finest weather day of the trip.|
|Dec 17||Scheduled field departure and return to Scott Base delayed because of light snow and cloud.page break|
|Dec 18||Dickinson, Goff, DeVries and Jennings depart (10:45) Table Mt arrive Scott Base; field gear unpacked and returned by 17:00.|
|Dec 19-20||R & R Scott Base while waiting for flight to Christchurch|
|Dec 21||Flight to Christchurch (clear skies, light wind) 11:30-18:30; night at Windsor Hotel|
|Dec 22||Dickinson, Goff, DeVries and Jennings depart Christchurch 08:30 for Wellington.|
4 Event Maps
Table 1. GPS Positions1
|STATION||LATITUDE (South)||LONGITUDE (East)||MSL ELEVATION||MAP DISTANCE|
|Table Mt Trig*||77 58
|Ian's Rock||77 57
|Sta-1 to Camp||201.4 m|
|Sta-1 to Sta-2||309.0 m|
|Ians's to Camp||402.5 m|
|Ian's to Sta-1||426.4 m|
|Ian's to Sta-2||552.7 m|
- Latitude is accurate to the nearest 0.5 seconds and the longitude is accurate to about 2.0 seconds. These equate to around 15 metres on the ground. The absolute height relative to mean sea level is within 20 metres. This is absolute position on the earth's surface relative to the coordinate of the Table Mt trig which has the above tolerances. Each of the four stations measured at Table Mt are, however, accurate relative to each other to within 0.10 metres for position and height.
Maps on the following two pages were compiled and drafted by Ian Jennings.
- Crate containing five Stihl chainsaw motors, with spare parts, assortment of drill bits and reamers, drilling tools
- Air compressor
- Sling container of drill rods and core tubes
- Six insulated core storage containers
6 Field Preparations
Because Jon DeVries was involved in field training with the event personnel, it was possible to cover exercises that were directly applicable to the conditions relevant to the field area of the event. Day one of Antarctic field training followed the standard exercises, but the use of fixed ropes on the steep rocky terrain of Observation Hill was covered on day two.
All of the drilling equipment was assembled, tested, and checked out in the vicinity of Scott Base. All other equipment (tents, radios, stoves etc) was checked at Scott Base and was fully operational before departure to the field.
7 Field Equipment
Generally all of the necessary field equipment was at Scott Base and in good working condition. All equipment was thoroughly checked before the event left for the field. Two of the primus stoves, which were issued, were found to be faulty. Of note is that one of them was brand new and had a faulty thread (manufacturing fault) where the burner screws into the fuel tank. This fault was not obvious and only showed up when the stove was hot which caused the thread to loosen and bleed off gas pressure.
- Erect any other available tents (polar, mountain) before setting up the Polar Haven. This is in case the weather deteriorates.
- Allow 2 hours to fully erect the tent with at least two people and ideally three.
- Reasonably calm conditions are needed to erect the tent.
- Allow 1 hour to take the tent down and pack it away with at least two people and ideally three.
Due to the nature of our field event which involved constant use of drilling gear, we requested extra spill kits and a tarpaulin to minimise environmental damage which could result from leaking oil or gas. However, we were only able to get one very old canvas tarpaulin and one extra spill kit (small size) before deployment. We finally acquired the large size, spill kit refills three days before returning to Scott Base.
To minimise the risk of environmental damage from this type of project, any machinery which is likely to have oil or fuel leaks should if possible have a drip tray. Further protection could then be given by the use of a tarpaulin.
One of the 20 litre containers of kerosene was contaminated with mineral turpentine which appeared to cause incomplete combustion in the primus stoves. All fuel containers 10 litres or larger should be able to either be fitted with a spout or a tap. All human waste needs to be triple bagged to be safe for handling and transportation.
8 Field Transport Operations
On the whole helicopter operations ran smoothly once schedules had been worked out. Our main camp moves and some of the drill site moves were done with the 3 Squadron UH-1H and went very smoothly and efficiently. There was a one day delay, due to weather, for our pull-out of the field.
The set-up in the BH 212, with the rear facing seats and the permanently fitted auxiliary fuel tank, limited its effectiveness when it came to moving cargo as an internal load. The other problem with the rear facing seats was that it was difficult to give the pilot directions when trying to locate a landing site for close support work. The lack of any ground to air communication with the BH 212 made it difficult to work with when the helicopter was approaching our camp or drill site and when moving drill gear from site to site.
For a moderate sized event such as this one, it was extremely useful and efficient to have a spread-sheet with all the helicopter loads for the put-in (Table 1). This information was also made it much easier to figure out loads for the pull-out. A copy of Table 1 was given to Rex Hendry.
9 Field Communications
After initial problems with an intermittent transmitter, communications with the Tait handheld radio and high-gain aerial, using the Mt Newall (Ch. 5) repeater, proved to be reliable from our camp site. High frequency communication was not successful from our location. The Tait radios were also used for communication between team members away from base camp.
In general the transfer of requests and information given over the radio were passed on to the appropriate people at Scott Base. However, on occasion this did not appear to happen. The format of the scheduled radio check-in was at times inconvenient for our event because we were still drilling. On numerous occasions when contacted for the evening check-in we explained our situation and requested leave of the weather and news. This was noted and given approval by the base operator. Then after the reading of the new and weather, we would be repeatedly called until we acknowledged the weather and news. This situation would not have been a problem except that we had to again stop work and go to the closest high point to transmit. A solution to this problem would be for Scott Base to contact all field parties and then pass on the weather and any messages to all parties, get an acknowledgment, and then anyone who wanted to listen to the news could do so. However, I believe the news is an important part of the communications set-up and should be continued.
The quantities of food taken into the field were certainly adequate. With the addition of the extra food (tortillas etc.), which the event supplied, there was a good variety. Unfortunately, we didn't count on the meat eating appetite of the ravenous hell driller from the West Coast. Only major complaints were not enough cheese due to a supply problem, and too many munchy bars which was our fault.
11 Drilling Operations
If the same system is used down to a depth of nine metres and at higher altitudes, the motor for the drill rig needs to be larger because it was working at its maximum capacity at 2000 metres. The Stihl 056 motor which was used to drive the compressor would probably be suitable. This system also needs modifications to the air cooling system. The simplest of these would be to extend the air intake away from the warm air environment created by the compressor.
The Winkie Drill tripod supplied by ANTNZ was also used beyond its safe working load at these depths. Unless the legs of the tripod can be braced at mid-height, the leg with the attached winch will bow out dangerously. The loading on the tripod was also increased by the addition of a block in the system to give a 2:1 ratio. The winch on the tripod is reasonably page break light weight and should be more robust for future drilling projects of this nature.
Any project which involves the use of machinery has industrial type risks. The project was completed without any injuries which is a reflection of the teamwork and competence of those involved in the project. The only medical problem was an pre-existing eye condition, which could have been aggravated by the exhaust fumes from the drill motor. Some thought needs to be put towards the modification of the exhaust system of the drill rig if the same system is used in the future, the exhaust system needs to be modified so that it is vented away from the drilling personnel. There is also a risk of burns from the present exhaust system.
A recommendation for future projects of this nature is that all personnel involved in drilling should wear steel capped Sorrels and safety helmets with attached grade 5 hearing protectors.
All party members were either in visual or radio contact at all times when we were doing field work on Table Mountain. The area covered during the time in the field was relatively safe terrain.
In general, weather conditions at Table Mt were mild enough to allow field work nearly the entire time (Table 2). However, the conditions were often very localised with warm coastal air masses moving up the Ferrar Glacier and cold Polar Plateau air masses flowing down the glacier. When these two air masses met in the Table Mt area, they would cause a local build-up of Stratus or Stratocumulus clouds. This would commonly occur from mid morning to late afternoon. This weather pattern occurred about 30% of our total time in the field. These conditions would sometimes result in light snowfall.
During the field season, no winds above 25 knots were experienced even though reasonably strong katabatic winds could be seen and heard blowing down the Ferrar and Tedrow Glaciers. The wind was predominantly 5 knots from the south west.
1 Data surveyed by Belgrave, Cairns, and Simonsen 4 Dec - 10 Dec, 1996.
* Used as fixed control for the other sites.