IMMEDIATE SCIENCE REPORT
K-048: WEST ANTARCTICA VOLCANO EXPLORATION (WAVE) EXPEDITION TO MOUNT MURPHY & EXECUTIVE COMMITTEE RANGE
Antarctica New Zealand October 1990 - January 1991
Phase two of the WAVE field programme involved detailed mapping and sample collection from the Mount Murphy Volcanic Complex (MMVC) and a return to the Executive Committee Range (ECR) to complete studies, at the northern end of this line of volcanoes.
The Mount Murphy Volcanic Complex has been deeply eroded to expose sections through the volcano which range from sub aqueous to sub aerial mode of eruption. The volcanic rocks rest on an eroded metamorphic basement complex of high grade metamorphic rocks cut by granitoid intrusions. A single outcrop of low grade sedimentary rock has yielded plant fossils - some of the first insitu fossil material to be discovered in Marie Byrd Land. Detailed study of continuous sections of volcanics up to 600m thick in the vicinity of Turtle Peak, Petril Nunatak, Heden Nunatak and Seechrist Peak has revealed a transition zone from sub aqueous to sub aerial eruption. These relationships together with high precision dating studies by the 40Ar/39Ar method promise to reveal much about the glacial-eruptive history of the volcano and to add to the growing knowledge concerning the level of the West Antarctic ice sheet during the Pliocene. Samples collected in association with this mapping will be used to assess the geochemical and penological evolution of the volcano. A number of satellite basaltic scoria cones on the flanks of the eroded MMVC have yielded upper and lower crustal and upper mantle xenoliths from which we can reconstruct a stratigraphic section through the lithosphere beneath the volcano.
For the last 10 days of field work the party transferred to Mount Hampton at the northern end of the Executive Committee Range (ECR). Here, sampling was assisted by close support from a BAS Twin Otter aircraft. This enabled some of the party to sample tephra layers from blue ice in the vicinity of Mount Waesche at the southern end of ECR and a visit to scoria cones of the USAS Escarpment. Samples for dating and geochemical study were collected from Mt Hampton, Whitney Peak (on the NW flank of Hampton) and the USAS Escarpment (Mt Aldaz). Lithospheric xenoliths were collected from scoria cones on Whitney Peak (NW Mt Hampton) and the USAS Escarpment.
2/ Proposed Programme
The second field season of the WAVE project aimed to visit several of the major volcanic complexes of the Kohler Range, principally Mount Murphy (Appendix 1) to undertake programmes of mapping and sample collection. Later in the season, it was proposed to move to the north end of the Executive Committee Range (ECR) to page break complete work from the foreshortened 1989/90 season. For the 1990/1991 season we aimed for a LC-130 put-in at Mount Murphy (75° 22′S, 110° 40′W) and from here to travel by sledge party to Toney Mountain (75° 48′S, 115° 50′W). In the latter part of the season the party would transfer (by LC-130) to Mount Hampton (northern ECR) and from here we planned visits to the USAS Escarpment (76°S, 124 - 129°W and Crary Mountains (76° 45′S, 117° 50′W) by a BAS supplied Twin Otter aircraft. Poor weather at Mount Murphy, which resulted in the loss of roughly 2/3 work time, necessitated a change in plans such that the proposed sledging trip to Toney Mountain was scrapped. Also, due to ski damage, the close support promised by the Twin Otter did not materialise and we were only able to transfer and return a party from Mt Waesche and to pay a brief visit to the USAS Escarpment before that aircraft returned to Rothera.
3/ Scientific Endeavours and Achievements
The two planned field seasons for the WAVE project have now been completed and despite rather poor weather conditions being encountered on both seasons, considerable success can be reported.
Detailed stratigraphic mapping has been undertaken on Mt Sidley, Mt Waesche and Mt Murphy. Sampling for geochemical study has been undertaken on Mt Sidley, Mt Waesche, Mt Cumming and Mt Hampton (ECR), the USAS Escarpment and Mt. Murphy. Suites of lithospheric xenoliths have been collected from numerous localities in ECR, the USAS Escarpment and Mt Murphy.
Results from the first field seasons work on xenoliths from ECR were presented at the Geological Society of New Zealand Annual Conference in December 1990. (Wysoczanski R.J. & Gamble J.A.: Lower Crustal xenoliths from the Executive Committee Range, West Antarctica.). Abstracts of papers have been submitted to the Organising Committee of the Sixth International Symposium on Antarctic Earth Sciences.
5/ Environmental Impact
Apart from the removal of rock specimens for scientific study the impact on the environment is assessed as negligible. Flags were removed from all flagged access routes on completion of work. All metallic, paper and plastic waste was returned to Mc Murdo for disposal. Human waste was buried at site.page break
6/ Future Research
Detailed analytical work on the materials collected during the 1989/90 and 1990/91 seasons is now underway. R.J. Wysoczanski has applied to the Royal Society of New Zealand for funding from the Prince and Princess Award Scheme to undertake important isotopic work at Royal Holloway & Bedford New College, University of London. Future work will involve placing the West Antarctic xenoliths into a plate tectonic perspective of the Pacific rim region. In the future it would be valuable to return to the Flood Range, Ames Range, Mt. Flint, Mt Petras, the Crary Mountains and Toney Mountain. Visits to these sites of volcanic activity were in the original scope of the WAVE programme, but they were cancelled due either to the inclement climatic conditions during the two seasons or to the breakdown of the Twin Otter.
7/ Management of Science in the Ross Dependency
The two WAVE field seasons involved seven personnel from three national Antarctic research programmes (NZARP, USAP & BAS). Planning and logistic arrangements proceeded according as anticipated. Our recce flight was delayed by several days but the put-in brought forward such that we were in the field on the designated day. Our pick-up at Mt Murphy was delayed form an anticipated 18 December 1990 until 2 January 1991 - frustrating, but a way of life in Antarctica. We had excellent support and advice from the base staff at Scott Base, but I would make a plea for a few more Macs in the science lab. I was never able to get on to a machine when I wanted to.
All WAVE personnel extend their thanks to all Scott Base staff for their assistance prior to and following our field season. Thanks also to our friends from "over the hill" notably Ric Campbell, Jill and the BFC staff and Kirk and Pete in the skidoo shop.