Journal and Proceedings of
The Royal Society of New South Wales
Volume 116 Parts 1 and 2 [Issued August, 1983]
CONTENTS
| AUTHORS & TITLES | PAGES |
| Lomb, N.R., Precise Observations of Minor Planets at Sydney Observatory during 1982 | 1-6 |
| Brophy, Joseph M. and Lassak, Erich V., The Volatile Leaf Oils of Melaleuca armillaris, M. dissitiflora and M. trycostachya | 7-10 |
| Dulhunty, J.A., Lake Dieri and its Pleistocene Environment of Sedimentation, South Australia | 11-15 |
| Glen, R.A. and Hutton, J.T., Silcretes in the Cobar Area, New South Wales | 17-23 |
| Glen, R.A., Lewington, G.L. and Shaw, S.E., Basement/Cover Relations and a Silurian I-type Intrusive from the Cobar Lucknow Area, Cobar, New South Wales | 25-32 |
| King, David, S., Astronomic Determination of Mass Segregation and Membership Probabilities in Galactic Clusters | 33-40 |
Vol. 116 parts 1-2 pp.1-6
Precise Observations of Minor Planets at sydney Observatory during 1982
N.R. Lomb
Abstract. Positions of 1 Ceres, 3 Juno, 4 Vesta, 7 Iris, 39 Laetitia, 51 Nemausa and 704 Interamnia obtained with the 23 cm camera are given.
Vol. 116 parts 1-2 pp.7-10
The Volatile Leaf Oils of Melaleuca armillaris, M. dissitiflora and M. trycostachya
Joseph M. Brophy and Erich V. Lassak
Abstract. The composition of the steam-volatile leaf oils of Melaleuca armillaris, M. dissitiflora and M. trycostachya has been determined by use of gas-capillary chromatography and mass spectrometry. The oil of M. amillaris contained 1, 8-cineole as its main component whilst M. trycostachya leaf oil contained major proportions of both 1, 8-cineole and α-pinene. M. dissitiflora was found to exist in two chemical forms characterized by oils rich in 1, 8-cineole and terpinen-4-ol respectively.
Vol. 116 parts 1-2 pp.11-15
Lake Dieri and its Pleistocene Environment of Sedimentation, South australia
J.A. Dulhunty
Abstract. Recent geological investigations have shown that the Oligocene Cordillo Surface (Wopfner, 1974) was deformed in mid Tertiary time into the Lake Eyre and Lake Frome structural basins separated by a tectonic divide. Sediments from late Tertiary to Holocene were deposited on both sides of the divide. Thus, Lake Eyre and Lake Frome has separate late Pleistocene ancestral lakes, and one large lake (Loffler and Sullivan, 1979) covering both structural basins, was unlikely to have occurred. It is proposed that the name Dieri should be preserved for the late Pleistocene ancestor of Lake Eyre, and the name Pilatapa could be used for the equivalent ancestor of Lake Frome.
Vol. 116 parts 1-2 pp.17-23
Silcretes in the Cobar Area, New South Wales
R.A. Glen and J.T. Hutton
Abstract. A recent, detailed geological survey of the Cobar area in central-western New South Wales has disclosed areas of silcrete development. In hand specimen and in chemical analyses, these silcretes closely resemble previously know occurrences found west of Cobar (Dolo Hills, N.S.W.) and northwest of Cobar (Tibooburra, N.S.W. and adjacent area of southwest Queensland). However, on outcrop scale Cobar silcretes differ from those further west in that they form only localized occurrences, rather than extensive sheets. Localities, descriptions in hand specimen and thin section, and chemical analyses are given to document these silcrete occurrences. Although Wasson et al. (1979) have rightly questioned the earlier report by Dury (1966) of silcrete occurrences around Cobar, the new data presented here enable the Cobar area to be retained as a silcrete locality.
Vol 116 parts 1-2 pp. 25-32
Basement/Cover Relations and a Silurian I-type Intrusive from the Cobar Lucknow Area, Cobar, New South Wales
R.A. Glen, G.L. Lewington and S.E. Shaw
Abstract. In the Cobar Lucknow area, 10 km NE of Cobar in central western New South Wales, the Wild Wave Granodiorite is intrusive into the Cambro-Ordovician Girilambone Group and is nonconformably overlain by fossiliferous rocks belonging to the Meryula Formation of the Early Devonian Cobar Supergroup. A biotite Rb/Sr age from the granodiorite is 418 ± 2Ma (Middle-Late Silurian). This date is similar to other biotite Rb/Sr ages obtained from other granitoids in the Girilambone-Wagga Anticlinorial Zone. The Wild Wave Granodiorite has a low initial 87Sr/86Sr ratio of 0.7051 ± 0.002 and is to date the only Silurian I-type granitoid recognised north of the Lachlan River in the Girilambone-Wagga Anticlinorial Zone. Other bodies – the Thule and Erimeran Granites, the Nymagee Igneous Complex, and possibly the Tinderra Granite – are all S-type. From the low initial ratios and the range of Rb/Sr ratios of possible source rock compositions, the source of the Wild Wave Granodiorite is inferred to be from mafic rocks in the lower crust.
Vol. 116 parts 1-2 pp.33-40
Astronomic Determination of Mass Segregation and Membership Probabilities in Galactic Clusters
David S. King
Abstract. Using positional as well as proper motion information allows a more reliable determination of the membership probabilities in the region of the galactic clusters. Applying a positional fit to cluster members indicates that the more massive stars congregate towards the cluster centre in NGC 6087 and NGC 3532.