Journal and Proceedings of
The Royal Society of New South Wales
Volume 102 Part 1 [Issued October 13, 1969]
CONTENTS
AUTHORS & TITLES
Dulhunty, J. & Eadie J. Geology of the Talbragar Fossil Fish Bed Area
Flood, P.G. Lower Devonian Conodonts from the Lick Hole Limestone, Southern
New South Wales
Guy, B.B. Granitic Development and Emplacement in the Tumbarumba-Geehi
District, N.S.W. (1) The Foliated Granites
Hails, J.R. The Nature and Occurrence of Heavy Minerals in Three Coastal Areas of
New South Wales
Lindsay, J.R. Stratigraphy and Structure of the Palaeozoic Sediments of the Lower
Macleay Region, North-eastern New South Wales
Ward, C.R., Wright-Smith, C.N. & Taylor, N.F. Stratigraphy and Structure of the
North-East Part of the Barrier Ranges, New South Wales
Brown, R.D. Where are the Electrons?
Keane, A. A problem with Mine Ventilation
PAGES
1-4
5-9
11-20
21-39
41-45
57-71
73-81
83-86
Vol. 102 Pt 1, pp.1-4
Geology of the Talbragar Fossil Fish Bed Area
J. A. Dulhunty & J. Eadie
Abstract Chert containing Jurassic plant and fish fossils occurs as loose blocks floating in soil
derived by weathering from Jurassic Purlawaugh sediments overlain by remnants of Pilliga
sandstone and underlain by Triassic Narrabeen sandstone. From field investigations it is
concluded that the loose blocks of chert represent displaced erosional remnants, and all that is
left, of an isolated lake-bed deposit now almost completely removed by erosion. The chert bed
appears to have accumulated over a relatively short period of time, probably less than 250 years,
and possibly as little as several seasons.
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Vol. 102 Pt 1, pp.5-9
Lower Devonian Conodonts from the Lick Hole Limestone, Southern New
South Wales
P. G. Flood
Abstract. Fifteen species and subspecies of disjunct conodonts are recorded from a measured
section of the Lick Hole Limestone. The conodonts, in particular Polygnathus lieguiformis dehiscens
Philip and Jackson, suggest a Lower Devonian (late Siegenian-early Emsian) age for the Lick
Hole Limestone.
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Vol. 102 Pt 1, pp.11-20
Granitic Development and Emplacement in the Tumbarumba-Geehi District,
N.S.W. (1) The Foliated Granites
Brian B. Guy
Abstract. In the Tumbarumba-Geehi district some of the granitic bodies that are in part foliated
display a close association in mineralogy, chemistry and field relationships with the surrounding
regionally metamorphosed psammopelitic sequence. These foliated rocks the Cooma-type
granites are characterized by the presence of clusters of biotite, occasional cordierite and patchy
zoning in the plagioclases. Chemically the rocks display low Ca contents and a high K:Na ratio,
features that are evident in the associated metamorphics. There is a distinct similarity in the
chemistry of biotites from the granites, their inclusions, and the high-grade metamorphics.
The following sequence of events is envisaged for the formation and emplacement of the
Cooma-type granites: (a) high-grade metamorphism of a psammopelitic sequence, segregation of
quartzo-feldspathic and biotite-rich sections, and some increase in Ca contents; (b) introduction
of sodium, breakdown of micas and the formation of a partial melt, with development of alkali
feldspars. Such reactions involve an increase in volume and thus a decrease in specific gravity of
the granites with consequent migration and emplacement to higher levels in the crust.
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Vol. 102 Pt 1, pp.21-39
The Nature and Occurrence of Heavy Minerals in Three Coastal Areas of New
South Wales
J. R. Hails
Abstract. A detailed mineralogical study has been undertaken in an attempt to determine the
sources of heavy minerals in three areas of New South Wales. The areas studied are Twofold Bay
and neighbouring South Coast districts between Pambula and Disaster Bay, Broken Bay near
Sydney, and the Mid-North Coast between Port Macquarie and Grassy Head. The percentage
variations of different minerals in both Pleistocene and Holocene sediments have been
evaluated. Diagnostic heavy minerals have been traced in some barrier and dune sands, and it is
believed that these were transported shorewards during marine transgressions accompanying
interglacial periods, and reworked locally by longshore drifting. Most of the minerals in the
unconsolidated deposits on the east Australian coast can be described as polygenetic because
they have been derived from various sources, and their origin is very complex in relation to both
time and place.
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Vol. 102 Pt 1, pp. 41-55
Stratigraphy and Structure of the Palaeozoic Sediments of the Lower Macleay
Region, North-eastern New South Wales
John F. Lindsay
Abstract. The Palaeozoic sedimentary rocks of the lower Macleay region have been divided into
six stratigraphic units which are, in ascending order; the Boonanghi Beds, the Majors Creek
Formation, the Kullatine Formation, the Yessabah Limestone, the Warbro Formation and the
Parrabel Beds.
The lowest exposed Carboniferous sedimentary rocks are turbidites; these pass up into poorlywashed sandstones and mudstones, which are in turn overlain by a well-washed shallow-water
sequences of sandstones, conglomerates and mudstones. The oldest Permian rocks exposed are
bioclastic limestones that pass upwards into interbedded mudstones and sandstones, some of
which are laminated.
There are two distinct sets of faults, one intersecting and displacing the other, and a set of major
folds carries some incongruent minor folds.
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Vol. 102 Pt 1, pp.57-71
Stratigraphy and Structure of the North-East Part of the Barrier Ranges, New
South Wales
C. R. Ward, C. N. Wright-Smith and N. F. Taylor
Abstract. The succession of beds outcropping along the axis of the Caloola Syncline, between
Sturt's Meadows and Nundooka is described. The lowermost strata are Upper Proterozoic beds
of the top part of the Torrowangee Group and they consist of shales, dolomites and tillites
overlain by shales and quartzites with a few dolomites. Detailed geological mapping has led to a
subdivision of this part of the Torrowangee Group into several rock units, and has shown an
unconformable relationship with overlying strata both of (?) Cambrian and of (?) Upper
Devonian age.
A thick sequence of (?) Upper Devonian quartzose sandstones and associated sediments of a
red-bed facies has also been mapped. These are apparently the marginal beds of the molasse
phase of the Lachlan Geosyncline.
Small deposits of (?) Lower Tertiary sediments occur, and these are overlain by widespread
remnants of silcrete, and younger deposits of ferricrete and kunkar. The eastern edge of the area
is covered by substantial deposits of Quaternary age, mainly alluvial silt and clay.
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Vol. 102 Pt 1, pp.73-81
Where Are the Electrons?
R. D. Brown
[Liversidge Lecture 1968]
First paragraph. When chemists come to interpret their observations in terms of the atomic
molecular theory of matter one of the first questions to be settled is: where are the electrons?
This may arise at a relatively elementary level in balancing a redox equation or using the octet
rule to derive a structural formula. At more sophisticated levels of valency theory the
interpretation of virtually all chemical and physical properties of compounds depends heavily on
a knowledge of how the electrons are distributed over a molecule.
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Vol. 102 Pt 1, pp.83-86
A Problem in Mine Ventilation
A. Keane
[Presidential Address 2nd April 1969]
1. The Problem. I am often asked, What does an Applied Mathematician do? Perhaps there are
as many answers to this question as there are applied mathematicians, but a review of a problem
which was attacked by a number of us about ten years ago and which is currently being further
investigated by an M.Sc. student at Wollongong will give some insight into applied mathematics
in action.
Applied mathematics is concerned with deducing solutions of problems in the real world by
using abstract mathematical techniques. The most important step involves the specification of a
model simple enough to be treated mathematically yet containing sufficient detail to approximate
reality. Herein lies the art of applied mathematics.
To illustrate the gradual development of sophistication, a problem on the ventilation of coal
mines is examined, starting with the simplest model and progressing through a series of
refinements. Ultimately, the complication of the model outstrips known techniques and the
interest shifts from the original problem to the justification of the mathematical methods used in
its solution.
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