AGSO's 1995-1996 Petrel Sub-basin Study has defined the structural and stratigraphic evolution of the sub-basin. Results of this work will help to promote and focus future exploration activity and reduce exploration risk, as well as provide an important input to on-going AGSO research in other parts of the Timor Sea region. Well Folio: The well folio contains 1:5,000 scale composite well logs of 31 wells in the Petrel Sub-basin, together with 6 cross sections at 1: 10,000 scale, that were generated by StratLog II, GeoQuest software system for well interpretation and display. Well composities are arranged in alphabetical order (Plates 2-32); cross sections are in enclosed envelopes (Plates 33-38). Each well composite displays gamma and sonic logs from Wiltshire Geological Services, together with lithology, lithostratigrapic units (as defined in the original well completion report), sequence stratigraphic units defined in this study, biostratigraphic data, hydrocarbon shows and source rock data (averaged for each sequence stratigraphic unit). Map and Seismic Folio: The Map and Seismic Folio is a supplement to the Petrel Sub-basin Study 1995-1996 Summary Report AGSO Record 1996/40. AGSO deep-seismic lines 1000/101, 2, 3, 5 and 6 and 118/18 were imported from digital data using Geoquest software and interpretation were imported into Petroseis seismic data file (sdf) for mapping purposes. The seismic study, in conjunction with interpretation of well data, was undertaken using a sequence stratigraphic approach. Major sequence boundaries on the seismic sections were identified from onlap and truncation surfaces or by abrupt changes in seismic facies. In general, bases of sequences were 'carried' rather than tops. Location of seismic lines are shown on Plate 1. Time structure contours of key surfaces are shown in Plates 2 to 8. Time isopach maps of key surfaces are shown in Plates 9 to 25.

As part of the Broken Hill Exploration Initiative (BHEI), Geoscience Australia and the Department of Primary Industries South Australia (PIRSA) recently embarked on a two-year joint project to better understand the deformational history and tectonic evolution of Palaeoproterozoic rocks in the Outalpa Inlier, South Australia. This project is one of several structural studies undertaken on these rocks although to date no consensus has emerged regarding the number, orientation and geometry of the main deformational events. To address this problem, detailed structural and stratigraphic studies were undertaken around Ameroo Hill and Tommie Wattie Bore region in the central part of the inlier where a well defined stratigraphic succession is exposed. Comparable studies undertaken in other parts of the Olary Domain indicate that the same stratigraphy and structural history are developed across the entire Curnamona Province and that the structures developed around Ameroo Hill are not atypical of the province as a whole. Included in the Olary stratigraphy is the regionally extensive and highly prospective "Bimba Formation", a marble and calc-silicate dominated unit known for its high base-metal content (Pb, Zn, Mn, Cu, Co). Geochronological studies have recently confirmed this unit as a correlative of the Ettlewood Calc-silicate in the Broken Hill Group and there is growing geochronological evidence (Page et al., 2000) that other parts of the Olary sequence can be similarly matched to equivalent units in the Broken Hill Domain. Lithostratigraphic nomenclature follows Conor (2000, 2001) who subdivided the Willyama Supergroup into two major units of contrasting magnetic susceptibility and composition: the Curnamona and Strathearn Groups. REFERENCES: Conor, C.H.H., 2000. Definition of major sedimentary and igneous units of the Olary Domain, Curnamona Province. MESA Journal, V.19: 51-56. Conor, C.H.H., 2001. Geology of the Olary Domain, Curnamona Province, South Australia: Field Guide book. PIRSA, Adelaide. Page, R.W., Stevens, B.P.J., Gibson, G.M. and Conor, C.H.H., 2000. Geochronology of Willyama Supergroup rocks between Olary and Broken Hill, and a comparison to northern Australia. In: Peljo, M. (compiler) Broken Hill Exploration Initiative Abstracts Volume, AGSO Record 2000/10: 72-75.

Orogenesis in Phanerozoic systems is rapid, diachronous, episodic, and involves the switching of tectonic modes (extension-compression). In contrast, many Archaean orogens have traditionally been viewed as having developed by relatively simple, long-lived, mono-mode deformational processes. New results, however, reveal that the late Archaean eastern Yilgarn Craton (EYC) evolved episodically and rapidly, with a diachronous series of approximately E?W coaxial switches in tectonic mode. Tectonic mode switching changed stress regimes and resulted in the development of `late basins?, the emplacement of granites, and early orogenic gold mineralisation diachronously from east to west (NE?SW). Fluids were driven from the lower crust (and below) via large-scale crustal imbricating thrust faults. These fluids promoted the passage of a compression-extension couplet along a basal detachment by successively `lubricating? faults (preparing the ground), and facilitating a propagating wave of foreland surge (D2a) and hinterland extension (D2E) followed by inversion, uplift and annealing (D2b). In this way, orogenic Au and westward orogenic surge with associated tectonic mode switches are linked. We predict that the compres-sion-extension couplets and early orogenic gold mineralisation propagated from the east to the west diachronously at a rate of ~3-5 m.y. between domains from ~2670 Ma to ~2650 Ma. Multiple mineralising episodes are also a predicted consequence of the orogenic surge model.

The Jurassic-Cretaceous Bight Basin is situated along the western and central parts of the southern Australian continental margin. The largely offshore basin extends from the southern tip of Western Australia in the west, to just south of Kangaroo Island in the east, where it adjoins the Otway Basin. The thickest depocentre in the basin is the Ceduna Sub-basin, which contains a sedimentary section in excess of 15 km thick. The deepwater Recherche Sub-basin adjoins the Ceduna Sub-basin and extends west along the southern margin as far as the Leeuwin Fracture Zone. Perched half-graben systems of the Denmark, Bremer and Eyre sub-basins lie to the north of the Recherche Sub-basin. The Duntroon Sub-basin adjoins the Ceduna Sub-basin to the east, and consists of a series of oblique extensional depocentres. The Bight Basin evolved through repeated episodes of extension and thermal subsidence leading up to, and following, the commencement of sea-floor spreading between Australia and Antarctica. The basin was initiated during a period of Middle-Late Jurassic to Early Cretaceous upper crustal extension. A northwest-southeast to north-south extension direction, superimposed on east-west and northwest-southeast-oriented basement structures, resulted in oblique to strongly oblique extension and the formation of en echelon half graben in the Denmark, Bremer, Eyre, inner Recherche, eastern Ceduna and Duntroon sub-basins. The areal extent of the early extensional structures beneath the thick Ceduna Sub-basin cannot be determined at present. The anomalously thick nature of the Ceduna Sub-basin may indicate, however, that Jurassic-Early Cretaceous rifts are present at depth. Post-rift thermal subsidence was followed by a phase of accelerated subsidence, which commenced in the Late Albian and continued until continental break-up in the Late Santonian-Early Campanian. During this phase of enhanced subsidence, the dominant structural feature was a system of gravity-driven, detached extensional and contractional structures, which developed in the Ceduna Sub-basin during the Cenomanian as a result of deltaic progradation. Evidence for upper crustal extension during this basin phase is limited to Turonian-Santonian extensional faulting, and the reactivation and propagation of Cenomanian growth faults. The commencement of sea-floor spreading at ~83 Ma was followed by a further period of thermal subsidence and establishment of a passive margin

The Broadmere structure occurs in the Batten Trough in the southern McArthure Basin. Analysis of seismic data over the basin provides a basinfill architecture and an insight into the determining fluid pathways throughout the evolving basin. System requirements: The presentation on this CD was created using standard Adobe Acrobat PDF format. You will need version 3.0.1 or later of the Adobe Acrobat Reader, to view the presentation.

An integrated package comprising geological, structural, geophysical, geochronological and geochemical data. The GIS encompasses the outcropping and covered portions of Palaeoproterozoic and Mesoproterozoic rocks straddling the NSW-SA border (the Broken Hill, Euriowie, Olary, Mount Painter and Mount Babbage Inliers). The GIS features recent data collected by the Broken Hill Exploration Initiative.

The Australian Southern Margin SEEBASE® Compilation represents many years of work by SRK in southern Australia in the petroleum, mineral and coal sectors. During this time SRK has undertaken numerous projects in southern Australia with both the private and government sectors. These projects have resulted in the development of a model of the geological evolution of southern Australia from Archean to Recent that is summarised in this GIS and report. The model is consistent with a wide range of datasets including airborne and satellite remote sensing, seismic, well and outcrop observations. The basins of Australia's Southern margin formed by the repeated reactivation of long-lived basement structures. By understanding the genesis and geometry of the old basement structures, we have produced a model for the evolution of the Southern Margin basins that explains their structural framework and architecture. This SEEBASE model and structural interpretation can now be used as the basis for a new understanding of the sequence stratigraphy and petroleum systems of the margin.

The Early Permian to Middle Triassic Bowen and Gunnedah basins in eastern Australia developed in response to a series of interplate and intraplate tectonic events located to the east of the basin system. The initial event was extensional and stretched the continental crust to form part of the major Early Permian East Australian Rift System that stretched at least from far north Queensland to southern New South Wales. The most commercially important of the rift-related features are a series of half graben that form the Denison Trough, now the site of several producing gas fields. The eastern part of the rift system commenced at about 305 Ma and was volcanic dominated. In contrast, the half graben in, and to the west of, the Bowen Basin were non-volcanic, and appear to have initiated at about 285 Ma. These half graben are essentially north-south in length with an extension direction of approximately east-northeast. Mechanical extension appears to have ceased at about 280 Ma, when subsidence became driven by thermal relaxation. The extension occurred in a backarc setting, in response to far field stresses that propagated from the west-dipping subduction system at the convergent plate margin of East Gondwana that was located to the east of the East Australian Rift System.

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