Journal and Proceedings of
The Royal Society of New South Wales
Volume 109 Parts 1 and 2 [Issued 26 May, 1976]
CONTENTS
AUTHORS & TITLES
Morgan T. L. and Robertson W. H. Precise Observations of Minor Planets at Sydney
Observatory During 1973 and 1974
Percival Ian G., The Geology of the Licking Hole Creek Area, near Walli, Central
Western New South Wales
Ashley, Paul M. and Chenhall, Bryan E., Mylonitic Rocks in the Young Granodiorite,
Southern New South Wales
Dulhunty, J. A., Potassium-Argon Ages of Igneous Rocks in the Wollar-Rylstone
Region, New South Wales
Pogson D.J., and Scheibner, Erwin, Structural Interpretation of New England Region
– Discussion
Rod, Emile, Structural Interpretation of New England Region – Reply
Moore, David and Roberts, John, The Early Carboniferous Marine Transgression in
the Merlewood Formation, Werrie Syncline, New South Wales
De Deckker, Patrick, Late Silurian (Late Ludlovian) Conodonts from the Kildrummie
Formation, South of Rockley, New South Wales
PAGES
1-6
7-23
25-33
35-39
41-44
45-47
49-57
59-69
Vol 109 pts 1-2, pp.1-6
Precise Observations of Minor Planets at Sydney Observatory During 1973 and
1974
T.L. Morgan and W.H. Robertson
Abstract. Positions of 1 Ceres, 3 Juno, 11 Parthenope, 18 Melpomene, 39 Laetitia, 40 Harmonia
and 185 Eunike obtained with the 23 cm camera are given
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Vol 109 pts 1-2, pp.7-23
The Geology of the Licking Hole Creek Area, near Walli, Central Western New
South Wales
Ian G. Percival
Abstract. In the Licking Hole Creek area, of central N.S.W., the Early-Middle? Ordovician Walli
Andesite is overlain unconformably? by 363 m of Cliefden Caves Limestone. The latter, of
probable Gisbornian-Eastonian age, includes a bedded Lower Member (consisting of big shell
unit, and overlying thinly-bedded unit), a massive Middle Member, and an Upper Member
(comprising the ‘Island’ unit, and overlying grey unit). Much of the limestone sequence is
inferred to have been deposited in a shallow-water environment, at or somewhat below wave
base. The conformably overlying Malongulli Formation contains graptolites of the Dicranograptus
hians Zone at the base, and an assemblage of the Pleurograptus tinearis Zone at the top. The
Angullong Tuff (of Bolindian age) succeeds conformably, and is in turn overlain unconformably
by Late Devonian clastics. The Ordovician succession is faulted, along the Columbine Mountain
Fault, against the Early Silurian Millambri Formation. The latter is disconformably overlain by
the late Llandovery Liscombe Pools Limestone. Intrusives mapped in the area include the
Licking Hole Creek Diorite, and a quartz-porphyry neck. Another major fault, the Wonga Fault,
extends obliquely across the area, merging with the Columbine Mountain Fault to the southwest.
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Vol 109 pts 1-2, pp.25-33
Mylonitic Rocks in the Young Granodiorite, Southern New South Wales
Paul M. Ashley and Brian E. Chenall
Abstract. Discontinuous zones of steeply dipping mylonitic rocks occur along the western
margin of the Young Granodiorite in southern New South Wales. The mylonitic zones are up to
300m wide and are best developed where the Young Granodiorite abuts against the Coolac
Serpentinite. Mylonitic rocks grade through foliated into relatively massive blotite granodiorite.
Primary biotite and plagioclase in the biotite granodiorite undergo mineralogical breakdown
during the mylonitization process, whereas quartz, microcline and muscovite appear simply to
recrystallize. Plagioclase tends to be the phase most resistant to deformation. Microstructures
developed progressively with increasing mylonitization suggest that ductile deformation, dynamic
recovery and recrystallization were the major operative processes.
The mylonitic rocks were possibly formed during an episode in which rocks of the YassCanberra Rise were thrust at a high angle over an ophiolite suite forming the eastern boundary of
the Cowra Trough. The thrusting may have been coincident with the final deformation and
cratonization of the Cowra Trough in the early Devonian.
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Vol 109 pts 1-2, pp.35-39
Potassium-Argon Ages of Igneous Rocks in the Wollar-Rylstone Region, New
South Wales
J.A. Dulhunty
Abstract. Potassium-argon age determinations are recorded for intrusive and extrusive alkaline
intermediate rocks, and teschenite intrusions, and the significance of the results is considered in
relation to the igneous chronology and geomorphology of the region. Late Triassic ages were
obtained for teschenite intrusions; middle Jurassic ages for alkali microsyenite and phonolite sills
and laccoliths, and late middle Triassic ages for trachyte and phonolite flows. Early Oligocene
and middle Miocene basalt flows are correlated with dated flows in adjoining areas, and the
significance of their mode of occurrence in relation to the development of the Goulburn Valley
is noted.
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Vol 109 pts 1-2, pp.41-44
Structural Interpretation of New England Region—Discussion
D. J. Pogson and Erwin Scheibner
Initial paragraphs. The paper, “Structural,Interpretation of New England Region” by Dr.
Emile Rod (1974), represents a criticism of the recent work of the Geologial Survey of New
South Wales compiled by Pogson (1972) and the suggested structural subdivision of State by
Scheibner (1972).
Although Rod (1974) rightly criticises the uage of the redundant term “Brisbane Block”
(Scheibner, 1972), this was corrected before his criticism (cf. Scheibner, 1974), there are many
points on which Rod (1974) himself should be corrected. Unfortunately, he has relied mainly on
previously published geological maps and other published geological information (cf. Rod, 1974,
p. 98). It is hazardous to rely solely on published information, because the rapid progress of
geological investigations means that publications are outdated before they reach the reader.
Geological maps become outdated during the process of drafting and printing, especially
preliminary large-scale maps of the 1:250 000 series, and technical production cannot keep up
with the flow of new information. This problem is being overcome by the updating of all
available information at the Geological Survey of New South Wales and this is available on
request. Therefore, Rod’s remark (p. 90) that “Not one map agrees with the other on the age
assignment” indicates that he does not appreciate this situation. If some of Rod’s criticism is
based on direct observation and field evidence, then he gives no reference to this work in his
paper.
The State geological map was compiled on the basis of information available in December, 1971
which is still to a large extent unpublished or has been published only recently (for example
Leitch 1974). This information was not considered by Rod and therefore his criticism is
unjustified. The structural subdivision of New South Wales was first published by Scheibner
(1972) and not Pogson (1972); hence, his criticism is wrongly directed. Rod, instead of
approaching the State Survey with a request for an explanation (which is the normal procedure in
the search for unpublished information), has made allegations of “guesswork” (Rod, 1974, p. 90).
His criticism is not constructive. He has retreated even from the stage of knowledge achieved 15
years ago (Voisey, 1959), leaving the eastern part of the New England Fold Belt as an unnamed
white “terra incognita” (Rod 1974, fig. 5).
The geology of the New England Fold Belt is very complicated and its explanation is hindered
by the fact that the mostly flysch-like, metamorphosed and often structurally highly deformed,
sequences contain few fossils. Despite this, it has been possible to establish several major
lithological associations which have general stratigraphic validity. Recently, Leitch (1974) gave a
brief description of these lithostratigraphic associations. More fossil evidence was gathered and
reviewed by Fitzpatrick (1975), and the bio- and lithostratigraphy of Silurian sequences is
reviewed in Pickett (in prep.). Further relevant data have been published by Runnegar (1974),
McKelvey (1974) and Leitch (1974, where a useful list of published and unpublished sources is
given).
In the light of the above facts, we have to refute the statements and arguments of Rod (1974) as
unfounded in respect of stratigraphic position of lithological associations shown on the State
geological map (Pogson 1972). This of course does not mean that changes and improvements
have not been made or will not occur in the future.
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Vol 109 pts 1-2, pp.45-47
Structural Interpretation of New England Region—Reply
Emile Rod
Initial paragraphs. I appreciate the opportunity provided by Pogson and Scheibner in their
discussion of my paper (Rod, 1974b) to set right some misconceptions.
The scope of the paper under discussion – as stated in the introduction – was to present the
results of a study of the geology and to set forth the conclusions of my investigations on the
structural interpretation of the New England Region. Pogson and Scheibner allege in their
introductory sentence that my paper “represents a criticism of the recent work of the Geological
Survey of New South Wales compiled by Pogson (1972) and the suggested structural subdivision
of the State by Scheibner (1972).” I disagreed with many structural interpretations of Scheibner
as advanced by him in several publications and also shown on some maps issued by the
Geological Survey of New South Wales. I found some deficiencies on maps and have
commented on them previously. If the scope would have been to write a detailed criticism of the
documentation which I had to use, it would have required a book.
In early 1973, when I started to scrutinize the geological maps of the New England Region in
preparation of the paper under discussion, I found that on several maps the sections were not
correctly constructed, that the effects of vertical exaggeration on angles of dip and on the
distribution of the rock masses in cross-sections was not understood by some geologists
compiling those sections. On nine adjoining sheets of the New England Region the sections
were compiled at six different vertical exaggerations and on two sheets the ratio of vertical
exaggeration shown on the maps was erroneous.
Prompted by my findings on those maps of the New England Region and by some observations
on indiscriminate use of vertical exaggeration in geological sections in other publications, I
decided to write a concise discussion on the use of vertical exaggeration in cross-sections (Rod,
1974a). This was a critical study which I wished to separate from the main body of my paper.
However, for obvious reasons nobody from the Geological Survey had any comments to make
up to now on this short paper entitled “Misrepresentations by indiscriminate use of vertical
exaggeration in geological sections”.
None of my critical remarks about the quality of some information shown on certain geological
maps produced by the Geological Survey of New South Wales have been refuted. Merely a few
weak excuses have been made.
However, if as a result of my comments the maps produced by the Geological Survey of New
South Wales should one day reach the standards of excellence of the maps issued by the
Geological Surveys of the neighbouring States of South Australia and Queensland (produced in
Queensland in partnership with the Bureau of Mineral Resources, Geology and Geophysics),
then my remarks will have served a good purpose.
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Vol 109 pts 1-2, pp. 49-57
The Early Carboniferous Marine Transgression in the Merlewood Formation,
Werrie Syncline, New South Wales
David Moore and John Roberts
Abstract. The Kyndalyn Member of the Merlewood Formation in the Werrie Syncline
represents a marine transgression into a sequence of terrestrial sandstone, conglomerate, shale
and interbedded volcanics. Lithologically the Kyndalyn Member consists mainly of mudstone,
but has concentrations of oolitic limestone conglomerate and polymictic conglomerate in the
south, and oolitic and skeletal limestone in the north. Analysis of the fabric of the oolitic
limestone conglomerate and the distribution of sediment types suggests that the Kyndalyn
Member was deposited on a shallow marine shelf east of a north-south trending coastline: the
coast was marked by a pebbly beach in which the gravel was concentrated by wave action during
the transgression; mudstone accumulated below wave base on the shelf; and oolitic and
biohermal limestone accumulated on local banks, oolites occasionally being swept on to the
beach forming oolitic limestone conglomerate. Geological mapping shows that the Kyndalyn
Member incorporates the fossil horizons from Hill 60, Watts Babbinboon, and Wolli in a
discrete unit within the Merlewood Formation, providing confirmation of Roberts’ (1975)
contention that faunas from all of these localities belonged to the same stratigraphic level: the
Gigantoproductus tenuirugosus Subzone of the Delepinea aspinosa Zone. Consequently, the Namoi
Formation, to which the Watts Babbinboon fauna was originally assigned, can confidently be
dated as no younger than Schellwienella cf. burlingtonensis Zone, or late Tournaisian to early Visean;
and the Merlewood Formation, which contains the Kyndalyn Member, as middle to late Visean.
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Vol 109 pts 1-2, pp.59-69
Late Silurian (Late Ludlovian) Conodonts from the Kildrummie Formation,
South of Rockley, New South Wales
Patrick de Deckker
Abstract. The Kildrummie Formation, previously known as Kildrummie Group, is redefined
and a type section is selected and described. Fifty-eight limestone samples from two parallel
sections were treated for the recovery of conodonts, thirty-eight of which yielded conodonts
belonging to forty-six form-species. The occurrence of Spathognathodus crispus, Ozarkodina jaegeri
and Ozarkodina anajdri in samples from the upper half of the Kildrummie Formation indicates a
Late Ludlovian age (interval of upper crispus to lower eosteinhornensis zones). No short ranging
conodonts have been recovered from the lower part of the formation but the occurrence of
Atrypoidea cf. australis Mitchell & Dun, in approximately the middle of the lower half of the
formation, also indicates a Late Silurian age.
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