Legacy product - no abstract available

No abstract available

The extended abstract describes the geophysical characteristics of the granite dominated geophysical map units of the Yilgarn Craton and the relationship between their deformation and gold mineralisation. Aeromagnetic data are not able to distinguish the five main granite geochemical groups. Gamma-ray spectromatric data provide some distinctin of the geochemical groups but their use is restricted to limited areas of outcrop. Faults host much gold but the majority of these structures are barren and spatial associations have been difficult to establish. Shear zones are irregularly distributed across the craton. Abundant intersecting shear zones, that transect both granite and greenstone, define a 200 km wide, north-trending corridor, with distinctive rhomboid to sigmoidal internal geometry. Greenstones in the corridor are extensively disrupded and strongly aligned with adjacent shear zones. This corridor correlates with the the region of highest gold endowment for the Yilgarn Craton and large deposits are spatially associated with bends and intersections of the shear zones. By contrast, shear zones are sparse in the Yalgoo Dome area in the north west of the Yilgarn Craton. The crustal architecture of this area is dominated by large ovoid bodies of granite. Adjacent greesntones are not regionally alligned, nor particularly disrupted internally, and gold endowment is low. These aparent contrasting structural styles and corresponding differences in gold endowment can be similarly applied to the Superior Province of Canada (Abatibi Belt, abundant intersecting shear zones, strongly aligned greenstone, and high gold endowment) and Australia's Pilbara Craton (few shear zones, oviod granite geometry dominant with little regional alignment of greenstone and low gold endowment).

In review Jan 2001 (internal)

No abstract available

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.

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.

A digital atlas comprising 25 plates

No abstract available

No abstract available