Structural study of the Officer, Arrowie and Stansbury Basins

Cambrian and Neoproterozoic basins in SA are underexplored despite bona fide oil or gas shows in all of them, and PIRSA has commenced a project to promote a higher level of awareness of these within the petroleum industry.

In March 2001, PIRSA commissioned SRK Consulting to provide an integrated regional interpretation of basement composition, structure and depth in the SA portions of the Arrowie, Stansbury and Officer Basins, and to investigate the effect of basement geology on basin evolution and petroleum systems. SRK’s approach primarily relied on the interpretation of magnetic and gravity data, calibrated with many other data sets including mapped geology, topography, event histories, wells and seismic. This involved a ‘bottom-up’ approach to basin analysis, starting with a rigorous understanding of basement geology. By integrating the plate-scale kinematic event history for these basins, an interpretation of their structural evolution through time could be mapped. Combined with a SEEBASE (Structurally Enhanced view of Economic Basement) map of depth to basement, these data will be applied by PIRSA to understand basin-phase architecture and petroleum systems in these underexplored early Palaeozoic – Neoproterozoic regions.

The results of these projects were presented by SRK at a June 2001 workshop organised by PIRSA and attended by ~40 delegates from the petroleum and mineral exploration industry, academia, and PIRSA geologists and geophysicists. SRK’s key findings for each of the three basins have been extracted from the project reports and are summarised below.

Arrowie Basin

  • The eastern Arrowie Basin overlies the Curnamona ‘Craton’, an almost circular crustal block which was not deformed during the Delamerian Orogeny but is surrounded by Delamerian mobile belts.
  • The craton was not significantly deformed in the Delamerian due to the presence of a large, strong mid-upper crustal Mesoproterozoic pluton.
  • Basin architecture is controlled by new Neoproterozoic and Cambrian rift structures and reactivated basement structures.
  • Four basin phases and tectonic events shaped the Arrowie Basin during the Neoproterozoic, early Paleozoic and Tertiary.
  • A SEEBASE model for the eastern Arrowie Basin shows basement topography, and can be used to map basin-phase distribution, migration pathways, and trap type and distribution.
  • The geometry of the eastern Arrowie Basin is dominated by a central basement ridge which separates two thick Neoproterozoic–Cambrian depocentres.
  • Up to 4 km of Neoproterozoic sediment fill the deepest parts of the eastern Arrowie Basin.

View the report online (PDF - 8.5Mb)

Stansbury Basin

  • The basement geology of the Stansbury Basin is dominated by three contrasting terranes which behaved very differently during basin evolution.
  • Terrane boundaries are a first-order control on basin architecture. Palaeoproterozoic shear zones are a second-order control.
  • Basin architecture is largely controlled by basement structures, composition, fabric and rheology.
  • Four basin phases and tectonic events shaped the basin during the Neoproterozoic, early Paleozoic and Tertiary.
  • Early Cambrian rifting and late Cambrian foreland flexure were the principal basin-forming events.
  • A SEEBASE model for the western Stansbury Basin shows basement topography, and can be used to map basin-phase distribution, migration pathways, and trap type and distribution.
  • A previously unrecognised sub-basin has been defined just to the south of Yorke Peninsula.

View the report online (PDF - 10Mb)

Officer Basin

  • The basement geology of the Officer is dominated by northeast-trending, contrasting terranes which amalgamated during the Mesoproterozoic along a network of major northeast-trending shear zones.
  • The present-day geometry of the Officer Basin was established in the late Cambrian – early Neoproterozoic Petermann Orogeny.
  • Basin architecture is largely controlled by basement structures, composition, fabric and rheology.
  • Northeast-trending Mesoproterozoic shear zones and terrane boundaries were a first-order control on basin evolution during the Paleozoic.
  • Northwest-trending Neoproterozoic fractures were a second-order control on basin evolution during the Palaeozoic.
  • The Officer Basin has largely evolved during compression, and has been significantly influenced by intracratonic processes operating in the Musgrave and Arunta Blocks to the north.
  • Seven basin phases and tectonic events shaped the basin during the Neoproterozoic and Palaeozoic.
  • A SEEBASE model for the Officer Basin shows basement topography, and can be used to map basin-phase distribution, migration pathways, and trap type and distribution.

View the report online (PDF - 8.5Mb)

Warburton Basin Atlas

For several years, the PIRSA Petroleum Group has undertaken a number of Warburton Basin studies addressing the issues of reservoir quality, natural fracture density and distribution, source rock quality, and hydrocarbon shows and discoveries. With the opening up of acreage in the Cooper Basin and entry of a number of new explorers, there is a need to consolidate previous reports and to value add the data such that industry can make informed decisions when siting petroleum exploration wells and more effectively evaluate the basin.

The current Warburton Basin study will result in creation of a GIS-based CD that could also prove beneficial to well site geologists when assessing cuttings and cores in exploration, appraisal and development wells. The CD, to be available in August 2001, will include:

 

  • lithology map
  • subcrop map (including dips and strikes)
  • stratigraphy (including formation tops)
  • well locations and status
  • thin-section descriptions
  • core photography
  • hydrocarbon shows
  • natural fracture system
  • petrophysical log responses
  • seismic sections and synthetic seismograms
  • top and base of ‘weathered horizon’
  • Z Horizon depth structure map
  • relevant reports.

This atlas is now part of the Cooper & Eromanga Consolidated Data Package.
To order a free copy please email pirsa.petroleum@sa.gov.au

For further information contact:

    Rod Boucher
    Linex Ltd
    2 McGowan St
    Bendigo Victoria 3550
    Ph. 03 5443 3216, fax 03 5443 3216
    E-mail: rodney@linex.com.au
    Website: www.linex.com.au