Wise, et al. reported in 2015 that deep seismic reflection data is collected around the world in order to image the structure of the crust. Two-dimensional seismic data can be processed in a variety of ways, each technique permitting investigation of different aspects of the data and thus of the geology the line is transecting. A focus of deep crustal seismic surveys has been to investigate the nature of the lower crust, the geometry across the Moho, or the geometry of paleosuture zones between crustal blocks. The processing methods that are applied to image the Moho at depths of 30–50 km can smooth over higher order reflectivity features in the upper crust. For example, the application of a low-pass filter emphasizes continuity between individual seismic traces, which enhances consistency between individual traces to produce a ‘smooth’ image.
An alternative method to extract more detail on the upper crust is to apply a processing method known as partially preserved amplitude processing, a proprietary method of HiSeis Pty Ltd. This processing technique emphasizes variation in signal strength by preserving the temporal relative amplitude ratio, which has the effect of sharpening the output image. This resulting image is designed to be more sensitive to fabric within a rock, particularly in the upper crust, but also to the presence of discontinuities.
In this paper the authors provide new observations on the upper and middle crust around the Olympic Dam Cu–Au–U deposit, South Australia, from seismic data reprocessed using the partially preserved amplitude technique. Olympic Dam is the type example of hematite breccia iron oxide copper–gold (IOCG) style deposits and lies buried ~400 m beneath sedimentary cover of the Stuart Shelf. A major challenge to exploration in much of the Olympic Copper–Gold Province is thick sedimentary cover that results in a reliance on geophysical data and limited drill-holes to obtain an understanding of the geology. In 2003, two orthogonal deep crustal seismic lines were acquired by Geoscience Australia, centred on the Olympic Dam deposit – 03GA-OD1 and 03GA-OD2
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