Other formats

    Adobe Portable Document Format file (facsimile images)   TEI XML file   ePub eBook file  

Connect

    mail icontwitter iconBlogspot iconrss icon

Victoria University Antarctic Research Expedition Science and Logistics Reports 1971-72: VUWAE 16

SCIENTIFIC ACHIEVEMENTS

page 5

SCIENTIFIC ACHIEVEMENTS

VUWAE 16A - PARTS 1 & 3 (McMurdo area)

  1. An evaluation of the use of a portable coring drill for obtaining oriented paleomagnetic samples was undertaken. In all 19 sites were sampled using the drill at Cape Crozier, Cape Bird, Cape Barne and Hut Point Peninsula. Oriented block samples were also collected for paleomagnetic determinations at Cape Barne, Cape Crozier and Fang Glacier.
  2. Detailed mapping and sampling of the McMurdo Volcanic Group at Mt. Morning while the following localities around McMurdo Sound were visited and sampled:-
    • Inaccessible Island.
    • Mt. Cis (Cape Barne).
    • Summit crater Mt. Erebus.
    • Fang Ridge, Mt. Erebus.
    • Abbotts Peak
    and areas at Cape Crozier.

Petrographic examination and detailed geochemistry will be carried out by Kyle on the material collected and the data will be used as part of Kyle's Ph.D. thesis.

PART 2 (Evans Neve)

  1. Of major importance was the discovery of fossils in the Bowers Group at the head of the Mariner Glacier 12-15 km south-west of Mt. McCarthy. These are the first body fossils to be discovered in the Bowers Group, and the first (apart from some plant remains) to be found in Northern Victoria Land. The fossils consist mainly of brachiopods and trilobites, and preliminary study suggests a Late Cambrian (approximately 500 million years) age for the upper part of the Bowers Group. The sequence in which the fossils were found is 1700 m thick, consisting of fissile shale in the lower half, passing gradationally upwards into sandstones above. These probably represent shallow marine deposits. The upper 360 of the marine sequence consists mainly of red sandstones, with rare fossils, trilobite tracks, and mudcracks, suggesting very shallow marine, possibly inter-tidal conditions. Above the red beds quartzitic sandstone and conglomerate of probably fluviatile origin occur. This is correlated with the Camp Ridge Quartzite seen further north.
  2. A further important discovery was the presence of Bowers Group rocks in the northern part of the Evans Neve, lying far to the west of previously known occurrences. It is possible that unvisited nunataks lying further west may also be composed of Bowers Group sediments. The previously unvisited southern end of the Salamander page 6 Range was found to consist not only of granite, as previous maps showed, but also of dolerite. An isolated exposure of conglomerate of unknown affinities was also mapped.
  3. Geological mapping and sampling of the McMurdo Volcanic Group was undertaken at The Pleiades where a basalt-trachyte-basalt eruptive sequence was recognised.
  4. Geological data for compiling the 1:250,000 Freyberg Mountain map were collected.

References:

Askin, R.A., Barrett, P.J., Kohn, B.P., and McPherson, J. G. 1971. Stratigraphic sections of the Beacon Supergroup (Devonian and older (?) to Jurassic) in south Victoria Land. Antarctic Data Ser. 2, Victoria Univ., Wellington. 88 pp.

Barrett, P. J., Kohn, B.P., Askin, R.A. and McPherson, J. G. 1971. Preliminary report on Beacon Supergroup studies between the Hatherton and Mackay Glaciers, Antarctica. N. Z. Jl Geol. Geophys. 14, 605-614.

Grapes, R. H., and Reid, D. L. 1971. Rhythmic layering in the Ferrar Dolerite, south Victoria Land, Antarctica. N. Z. Jl Geol. Geophys. 14, 600-604.

page 7

VUWAE 16B

  1. Detailed stratigraphic sections were measured with staff and level at the following localities:-
    • Mistake Peak
    • Shapeless Mountain (6 sections)
    • Skew Peak
    • Mount Bastion
    • Robison Peak
    • Mount Fleming
    • Mount Feather
    • Mount Warren
    • Escalade Peak
    • Swartz Nunatak
    • Mount Kempe
    • Rotunda
    Collections of rock samples were taken for petrographic description and analysis from all sections measured. The section descriptions will be made available to interested geologists in the same way as last year's work (Askin et. al., 1971).
  2. The large collection of fossil plants made last season (Barrett et. al., 1971) was increased this season by even better specimens of leaves and stems from the Permian and Triassic coal measures. Glossopteris leaves up to 40 cm long with veins clearly preserved were found at Mt. Fleming, and a varied collection of well-preserved calamitid stems, ginkos, and fern-like fronds up to 50 cm across were recovered from a locality at Shapeless Mountain. In addition, Glossopteris and Gangamopteris leaves were found in shale that graded down into the uppermost glacial beds 30 cm below. This is the lowest stratigraphic occurrence of identifiable plant fossils in the Transantarctic Mountains, and will provide an age for the youngest glacial beds.
  3. A more precise age for the carbonaceous beds may be obtained from fossil pollen and spores to be extracted from samples collected this season. About 15 samples from last season have yielded pollen assemblages, though with varying degrees of preservation, and we hope that these, together with microfossils from samples collected this season, will allow detailed correlation with Australian microfloral zones.
  4. Further geological data were gathered for the compilation of a 1:250,000 map of the Mount Harmsworth 'Quadrangle', being prepared from the U.S. Geological Survey's reconnaissance series as a topographic base. Reconnaissance mapping of areas of Beacon strata in this area is now complete, and the University of Wyoming is providing data on areas of basement rock that they have been working on in the southeast corner of the sheet. In addition most of the Beacon areas on the Taylor Glacier sheet to the north have been mapped.page 8
  5. Samples were collected from the rhythmically layered Mount Warren intrusion for Mr. Grapes to continue his study (Grapes and Reid, 1971) of this unusual feature. From the same camp a stratigraphic section through the Aztec Siltstone was measured. This will be included by Mr. J. McPherson in his M. Sc. thesis on the depositional environment and geochemistry of the Aztec Siltstone, which is based largely on last season's fieldwork.