Journal and Proceedings of
The Royal Society of New South Wales
Volume 123 Parts 3 and 4 [Issued December, 1991]
CONTENTS
AUTHORS & TITLES
Fowler, T.J., Limestone Olistoliths in the Kildrummie Formation near Cow Flat, New
South Wales
PAGES
Osborne, R.A.L., Palaeokarst Deposits at Jenolan Caves, New South Wales
Coenraads, Robert R., Palaeogeography of the Braemar Deep-Lead Sapphire Deposit,
New South Wales
Theses Abstracts
[Available in a separate page]
Fenton, Ronald R., Stereochemical Studies on Metal Chelates of Novel Asymmetric
Ligands
Minty, Jnr., E.J., Late Pleistocene Geocryology of the Bogong High Plains.
59-73
49-57
75-84
85-86
87
v123 pts 3-4, pp.49-57
Limestone Olistoliths in the Kildrummie Formation Near Cow Flat, New South Wales
T. J. Fowler
Abstract. The Cow Flat limestone quarries, south of Bathurst expose massive tabular megaliths
(up to 750m long) of coarsely granular limestone designated as Kildrummie Formation (formerly
Group). These blocks are enclosed within a silicia volcaniclastic unit of the Campbells
Formation.
Facies characteristics of the silicic volcaniclastics suggest that they are deep-water massflow
deposits. Structural relations of limestones to host volcaniclastics indicates that the former are
allochthonous blocks (olistoliths) . The silicic volcaniclastics and limestones are correlated with
the shallow-marine Late Silurian Mullions Range Volcanics on the western side of the Hill End
Trough, northwest of Cow Flat. It is suggested that at this time the Hill End Trough had a
southward sloping basin floor. This and other occurrences of limestone olistoliths in the deepmarine areas flanking the Molong Rise may have resulted from vertical movements associated
with the Late Silurian Bowning Orogeny, or from collapse of unstable fault scarps bordering the
rifting Hill End Trough.
Return to Top
v123 pts 3-4, pp.59-73
Palaeokarst Deposits at Jenolan Caves, New South Wales
R.A.L. Osborne
Abstract. Limestone breccias and internal sediments with unconformable stratigraphic relations
to bedrock are exposed in cave walls at Jenolan Caves. These deposits show no sign of
deformation and geopetal structures in the deposits indicate that they were deposited after the
last major deformation to affect the limestone. They are highly lithified and clearly pre-date the
development of the present cave system. The breccias and internal sediments are interpreted
here as palaeokarst deposits filling caves, or possibly an extensive cave system, that developed in
the limestone during Permo-Carboniferous times.
Return to Top
v123 pts 3-4, pp.75-84
Palaeogeography of the Braemar Deep-Lead Sapphire Deposit, New South Wales
Robert R. Coenraads
Abstract. Exploration areas for deep lead sapphire deposits, such as those found at Braemar in
the New England gemfields, northeastern New South Wales, may be defined via mapping of
palaeochannels in which the deposits are situated. Palaeotopographic reconstruction was carried
out using the elevation of the contact between the Tertiary volcanic rocks and the Palaeozoic
basement, as well as drill hole data where available. The potential sapphire-bearing
palaeochannels have been delineated within the zone in which the 19-23 million year old
volcanics forming the western portion of the Central Volcanic Province (the West Central
Province) overlap onto 32-38 million year old sapphire bearing volcanics forming the eastern
portion of the province (the East Central Province). In this zone, the 19-23 million year old
basaltic lavas flooded a number of major palaeodrainage systems already containing 32-38
million year old basalt flows and alluvial deposits reworked from them.
Potential sapphire deposits have been delineated in the Braemar palaeochannel and its tributaries
up-palaeostream from the Braemar sapphire mine, in which sapphires are recovered along with
other heavy minerals, with the highest concentration occurring at the base of the channel.
"Braemar-type" deep lead deposits considered in this paper had approximately 10 million years
in which to form, and required the presence of a younger basalt capping (19-23 niillion year old)
for their preservation.
Potential sapphire-bearing alluvials are also delineated along the topographically inverted palaeoSwan Brook. The extent of these "deep lead" deposits to the east of Braemar, in palaeochannels
that drained the sapphire-bearing East Central Province, is related to the easternmost incursions
of the lavas of the West Central Province.