Library Open Repository

Structure and sedimentology of the Curdimurka Subgroup, northern Adelaide Fold Belt, South Australia

Downloads

Downloads per month over past year

Mackay, WG (2011) Structure and sedimentology of the Curdimurka Subgroup, northern Adelaide Fold Belt, South Australia. PhD thesis, University of Tasmania.

[img] PDF (Front matter)
Final_Thesis_De...pdf | Download (830kB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapters 1-2)
Chs_1_and_2.pdf | Download (6MB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapter 3)
Ch3.pdf | Download (6MB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapter 4)
Ch4.pdf | Download (3MB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapters 5-6)
Chs5_and_6.pdf | Download (5MB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapter 7)
Ch7.pdf | Download (12MB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapter 8)
Ch8.pdf | Download (6MB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapters 9-10)
Chs9-10.pdf | Download (3MB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (References and appendix)
References_and_...pdf | Download (1MB)
Available under University of Tasmania Standard License.

Abstract

The Curdimurka Subgroup is the upper unit of the Callanna Group, the basal group of
a thick Neoproterozoic metasedimentary dominated succession that is preserved as the
Adelaide Fold Belt. Throughout the fold belt, the Curdimurka Subgroup typically crops
out as megaclasts within breccias, the majority of which formed as salt diapirs or other
salt-tectonic related bodies. However, within the Willouran Trough, a depocentre that
formed early in the evolution of the northern Adelaide Fold Belt, the package is less
fragmentary, albeit bounded by tectonic and brecciated contacts. In this type area of the
Curdimurka Subgroup, about 6,000 m of semi-coherent strata are preserved. By examining
the stratigraphy and structure of the Curdimurka Subgroup, this study intends to develop an
understanding of the early development of the northern Adelaide Fold Belt.
Deposition of the Curdimurka Subgroup was mainly in low energy, shallow water to emergent
conditions, with periods of sub-wave base deposition. Evidence from evaporite mineralogy
and stable isotope geochemistry suggest that it was deposited in marine conditions, but
a lacustrine setting cannot be ruled out. Curdimurka Subgroup depocentres evolved
within a rift environment, subsequent to an initial phase of syn-rift, mantle-plume related
volcanism. The outcropping part of the succession is lacking in coarse-grained rudaceous
facies, a feature interpreted to record sedimentation distal to basin-marginal sediment input
points. Detrital zircon age populations demonstrate a clear upsection trend from proximalto
distal-source area contribution, a trend which is consistent with conceptual models of
broadening drainage patterns with increasing rift basin maturity.
Field relationships show that the area was subject to three deformation events. D1 produced a
diverse array of macroscopic structures, including listric normal faults, inclined to recumbent
folds and low angle reverse faults. Deformation is interpreted to have accommodated bulk
extension associated with gravity spreading above a décollement positioned at the base
of the Curdimurka Subgroup. Localised compressional structures formed in response to
translation above perturbations along both the décollement surface, and additional layer-subparallel
fault zones positioned higher in the Curdimurka Subgroup succession. Withdrawal
and local diapirism of a parent salt layer positioned in older Arkaroola Subgroup strata
provided the gravitation instability to drive D1. The timing of this event is constrained by
associated high level accommodation development, involving complex sub-basin growth,
during Cryogenian Umberatana Group sedimentation,
D2 produced upright, northwest – southeast trending folds with a penetrative axial plane
cleavage, and northeast dipping reverse faults. D3 produced open, southwest trending folds,
local refolding of F2, and a spaced cleavage oriented at a high angle to bedding. Both
D2 and D3 occurred during a Cambrian basin inversion event, the Delamerian Orogeny.
Monazite geochronology shows that peak metamorphism occurred during the Delamerian
Orogen, at 509 ± 5 Ma. A second thermal event occurred at 429 ± 9 Ma, approximately
contemporaneous with the intrusion of the British Empire Granite in the Mt Painter Inlier,
130 km east of the study area.

Item Type: Thesis (PhD)
Keywords: South Australia, Adelaide Fold Belt, structure, sedimentology, Callanna group, Neoproterozoic
Additional Information:

Copyright © the Author

Date Deposited: 09 Dec 2011 01:27
Last Modified: 15 Sep 2017 01:06
Item Statistics: View statistics for this item

Actions (login required)

Item Control Page Item Control Page