The Sandstone greenstone belt is located on the boundary between the Southern Cross and Murchison Domains of the Youanmi Terrane of the Yilgarn Craton. Geological mapping of the area, where extensive sheetwash and other regolith cover obscure large portions of the bedrock, was completed in 2005 by the Geological Survey of Western Australia. Projection of structural data to depth led to a hypothesis that the Sandstone greenstone belt is a refolded syncline. Model generation relied on the contrasting densities between the surrounding granites and the greenstone belt, and the strong magnetic susceptibility of the banded iron-formation units within the greenstone belt.
These physical characteristics were exploited during inversion of high-resolution potential-field data to define subsurface density and susceptibility distributions. The extents of these dense and magnetic bodies were defined by appropriate property value distributions and compared to profile information from a seismic reflection survey. The resulting 3D model constrains the thickness of the greenstone belt and geometry of its internal structure, which confirms the refolded syncline hypothesis.
Although the Sandstone greenstone belt is located in the hanging wall of the tectonic domain-bounding Youanmi Shear Zone, our model does not provide evidence for distinct differences between the Murchison Domain in the west and the Southern Cross Domain to the east of the Youanmi Shear Zone. More information can be found in GSWA Record 2015/11.
For further information contact:
3D.geoscience@dmirs.wa.gov.au