No abstract available

The Gawler Craton has been defined as that region of South Australia where Archaean to Mesoproterozoic crystalline basement has undergone no substantial deformation (except minor brittle faulting) since 1450 Ma (Figure 1; Thomson, 1975; Parker, 1993; Daly et al, 1998). The eastern and southeastern boundaries conventionally are defined by the Torrens Hinge Zone (THZ), although Gawler Craton basement that was deformed during the Delamerian Orogeny is known to the east of the THZ (eg Barossa Complex, Peake and Denison Inliers). The southern boundary corresponds to the inboard edge of the continental shelf. The Gawler Craton and the East Antarctic Craton are rifted segments of the Mawson Continent (Fanning et al, 1995). Western, northwestern and northern boundaries of the Gawler Craton are defined by the faulted margins of thick Neoproterozoic and younger basins. As a consequence of the extensive surficial and sedimentary basin cover, the level of understanding of the craton's geology and prospectivity are limited in comparison with most other Australian Archaean and Proterozoic cratons. Application of high-resolution regional aeromagnetic surveying during the mid-1990s (South Australian Exploration Initiative - SAEI), for the first time allowed an integrated interpretation and synthesis of the geology of the craton (Fairclough and Daly, 1995a; Fairclough and Daly, 1995b; Schwarz, 1996). A revised interpretation of the tectonic evolution of the Gawler Craton incorporating SHRIMP U-Pb geochronology, was presented by Daly et al (1998). Three principal orogenies have been proposed: The Sleafordian Orogeny (peak metamorphism at ~2420-2440 Ma), the Kimban Orogeny (KD1-KD2-KD3: 1845-1700 Ma), and the Kararan Orogeny (~1650 Ma and 1565-1540 Ma). It has been suggested that the Kararan Orogeny in the western and northern Gawler Craton represents the continental collision of the 'eastern proto-Yilgarn' and the Mawson Continent (Daly et al, 1998). The geodynamic significance of the Sleafordian and Kimban Orogenies is unclear. Subdivision of the Gawler Craton into tectonic domains has evolved as further information has become available (Figure 1; eg Parker, 1993; Flint and Parker, 1982; Drexel et al, 1993; Teasdale, 1997). In general the definition and nature of the domain boundaries are not well understood - addressing this problem is a key objective of the Gawler Craton Project. The resultant framework will be important for assessing prospectivity because the ore-forming systems are products of crustal-scale processes that may vary between tectonic domains. The contents of this GA Record were written in 2000, and were presented on the Gawler Project website prior to the publication of this GA Record.

Existing age constraints for geological events in the Tanami Block come predominantly from U-Pb geochronology of i) detrital zircons in sediments, and ii) magmatic zircons in granitoids. These constraints have been used together with observed and inferred geological relationships to help constrain timing of stratigraphy, magmatism, deformation, metamorphism and Aumineralisation (e.g. Vandenburg et al., 2001). Ongoing GA/NTGS zircon geochronology is continuing to refine our understanding of the stratigraphy and magmatic history of the Tanami, with attendant implications for tectonic evolution. In this regard it is noteworthy that detrital zircon ages of ~1815 Ma from the Killi Killi formation require either (or both) a revision of existing stratigraphy, or that the so-called Tanami Orogenic Event significantly post-dates ~1815 Ma, in contrast to previous estimates of ~1845 - 1830 Ma. However, detrital and magmatic zircons can provide no direct constraints on timing of deformation, metamorphism and Au-mineralisation, and consequently our current understanding of these processes in the Tanami region is relatively poor, despite being critical to predictive exploration models.

No abstract available

Presented at the Evolution and metallogenesis of the North Australian Craton Conference, 20-22 June 2006, Alice Springs. The Tennant Creek goldfield, the third largest goldfield in the Northern Territory, producing over 150 tonnes of gold (Wedekind et al., 1989), was only discovered in the mid-1930s due to the association of gold with ironstone rather than quartz veins. Over the last two decades ironstone-hosted gold deposits have been included in the group of deposits termed iron-oxide copper-gold (IOCG) deposits (Hitzman et al., 1992). Elsewhere in the Northern Territory, prospects with IOCG characteristics have been recognised in the southeastern Arunta (Hussey et al., 2005), and potential for these deposits has been recognised in the Mount Webb area of the Warumpi Province (Wyborn et al., 1998). <p>Related product:<a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=64764">Evolution and metallogenesis of the North Australian Craton Conference Abstracts</p>

This abstract discusses the metallogeny of the North Australian Craton and possible links to the assembly and breakup of Nuna, the Paleoproterozoic supercontinent. Before ~1750 Ma, deposits such as VHMS, porphyry Cu and orthomagmatic Cu-Ni deposits formed during the assembly of the NAC as the Kimberley, Numil-Abingdon and Aileron provinces converged and were then accreted onto the NAC. These deposits were formed in arc and backarcs, which generally involved local extension, within overall convergent geodynamic settings. After ~1750 Ma, the metallogeny changed, with deposits such as Broken Hill- and Mt Isa-type Zn-Pb-Ag deposits, unconformity U and iron oxide Cu-Au(U) deposits forming largely during extension associated with the breakup of Nuna.

As part of the 11th SGA Biennial meeting in Townsville, Australia, the Organising Committee is offering a series of field trips to examine the geology and setting of important mineral provinces in Australia, New Zealand and Papua New Guinea. The purpose of this short article is to provide an overview of the metallogeny of Australia, which is considered within the framework of the geological evolution of the Australian continent.

A metallogenic map depicts concentrations of deposits of metals within their geological framework, and attempts to relate one to the other. The more familiar mineral deposits map, on the other hand, is designed to show the geographical distribution of mineral deposits, possibly with indications of their size, state of exploitation, and other factors.The exact nature of the legend for a metallogenic map is governed by the relationships assumed to exist between the concentrations of metals and their settings: map design can be used to emphasize the more important facts and employs symbols each of which incorporates several parameters. Metallogenic maps are not simple and easily read documents, but are complex representations of complex relationships, and so should convey a great deal of information. In 1956, at the 20th Session of the International Geological Congress in Mexico, the Commission for the Geological Map of the World set up a Sub-Commission for the Metallogenic Map of the World. After studying available maps showing mineral deposits, the sub-commission recommended that although countries should continue experimentation towards suitable presentation of data, an Editorial Committee for the Metallogenic Map of Europe should be set up; this committee would work towards firstly a legend for metallogenic maps in general, and secondly a Metallogenic Map of Europe. The committee was fortunate in that the compilation of the Tectonic Map of Europe was well advanced when it began its work. In 1964 a legend reflecting the basic philosophy of the Metallogenic Map of Europe was prepared and compilation begun. The first two sheets of the Metallogenic Map at a scale of 1:2 500 000 were published in 1969. Australia was represented on the sub-commission from 1960 onwards. The presentation of the legend for the map of Europe paved the way for the Australian compilation. A suitable area was selected for a pilot compilation early in 1965 and the main study began in 1966. A suitable geographical base map of Australia at 1:5 000 000 was available and a geological map on this base was in the final stages of publication. The second edition of the Mineral Deposits Sheet of the Atlas of Australian Resources (scale 1:6 000 000) was published during 1965. In that year the Tectonic Map Committee of the Geological Society of Australia began work on a Tectonic Map of Australia, and the philosophies and preparation of that and the Metallogenic Map were developed together.

Extended abstracts from the conference

Legacy product - no abstract available