Reappraisal of Legacy Reflection Seismic Data for the Prospection of Iron Mineralisation

Westgate, M.; Manzi, M.; James, Ian W.; Harrison, Wesley

doi:10.3997/2214-4609.202020140

Cited by 3 publications

(7 citation statements)

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“…To present the physical property measurements, we used the lithological data and the physical property measurements to recreate downhole-logging results (Figure 9). To better understand the seismic response of the different rock units, we conducted 1D-synthetic seismogram using a MATLAB script (Westgate, 2020) by calculating the reflection coefficient and convolving it with a 130 Hz Ricker wavelet. Pyroxenites show the highest magnetic susceptibility (0.014224524 SI) and the lowest density (2744.5 kg/m 3 ) (Figure 9).…”

Section: Resultsmentioning

confidence: 99%

Multi‐geophysical methods for characterizing fractures in an open pit mine, western Bushveld Complex, South Africa

Rapetsoa,

Gomo,

Manzi

et al. 2024

Geophysical Prospecting

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In the Bushveld Complex, South Africa, open pit mines are faced with a challenge of rock slope stability due to geological structures (fractures, faults and dykes) that compartmentalize the rock mass. Geophysical surveys (seismics, magnetics and electrical methods) were conducted in a 0.2 km2 area at Tharisa mine, with the goal to delineate fractures that may be potential conduits for water migration into the pit. Special processing techniques were applied to the dataset to obtain good quality seismic, magnetic and resistivity models. The P‐wave velocity models show distinct low velocities in the centre of the seismic profile, indicating the presence of weak zones associated with faulting or fracturing. Seismic reflection method was used to image the deeper discontinuities and mineralization contacts. Near surface reflections are observed throughout the profiles and are correlated with the contact between the chromitite and host rock. Ground magnetic surveys were conducted to delineate dykes and fractures. De‐trending and de‐culturing techniques were applied on the magnetic data for correcting regional and temporal variations. The low magnetic regions indicate the presence of fracture systems in the subsurface, whereas the high magnetic region is correlated with the dolerite dyke that crosscuts the pit. The electrical resistivity tomography exhibits linear low resistivity contrast zones that differentiate between the fractured and undisturbed hard rock at an estimated depth of 4–10 m. Resistivity shows discontinuities that suggests the presence of fracturing and dyke‐host rock contacts. Correlation among magnetics, P‐wave velocity models, resistivity section and seismic data is evident when overlaying the different datasets, implying that the low magnetic regions are highly weathered and prone to fracturing. The integration of geophysical data is encouraging, because it was able to image the depth to the bedrock, fractures within the host rock and dyke in a complex mining environment.

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Section: Resultsmentioning

confidence: 99%

Multi‐geophysical methods for characterizing fractures in an open pit mine, western Bushveld Complex, South Africa

Rapetsoa,

Gomo,

Manzi

et al. 2024

Geophysical Prospecting

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“…The observation that the Moshaweng fault coincides with a distinct change in the pattern of the basement magnetic anomalies (smoother to the west vs. sharper to the east) strongly suggests that the Dwyka Group is limited to the western side of the Moshaweng fault. Surface exposures and suboutcrops of the Karoo Supergroup are currently unknown to the east of the Kuruman Hills (Haddon and McCarthy, 2005;Gabrielli, 2007;Westgate, 2020), but close to the western end of the profile, in Botswana, the Dwyka rocks are extensively overlain by younger Karoo Supergroup sediments attributed to the Ecca and Beaufort groups (Key and Ayres, 2000;Haddon, 2004).…”

Section: Surface Geology and Geophysics Of The Kbf03a Profilementioning

confidence: 99%

“…Westgate (2020) introduced an attribute that is a composite of either of the two above mentioned instantaneous attributes and the novel symmetry attribute (Manzi et al, 2019;Westgate, 2020). The composite attribute is a hue-saturation-intensity (HSI) image that is created by assigning one of the instantaneous attributes to the intensity component of the image and assigning the symmetry attribute to the hue component of the image.…”

Section: Seismic Attributesmentioning

confidence: 99%

“…The composite attribute is a hue-saturation-intensity (HSI) image that is created by assigning one of the instantaneous attributes to the intensity component of the image and assigning the symmetry attribute to the hue component of the image. The symmetry component, as explained by Westgate (2020), is calculated by running a window through the seismic section of user-defined size and the centre value of the window is calculated to give the local symmetry of the data within that window. The result is a doubling of the wavelet limbs -due to symmetry attaining a maximum at every trough and peak and a minimum at every point of inflection -which adds a layer of detail to the to the wavelet anatomy.…”

Section: Seismic Attributesmentioning

confidence: 99%

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A reappraisal of legacy reflection seismic data from the western margin of the Kaapvaal craton, South Africa, with implications for Mesozoic-Cenozoic regional tectonics

et al. 2021

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“…More than 20,000 line km of 2D data were acquired in the 1980s and 1990s, covering several important mining regions (Durrheim, 2016; Terracin & Manzi, 2017; von Ketelhodt et al., 2019). New insights obtained from legacy data may profit future mine planning operations by finding new ore deposits or constraining discovered ones with greater accuracy, ultimately giving a superior estimation of resources and providing information that may assist with, for example, siting and sinking future shafts (Manzi et al., 2019; Westgate, 2020). In addition, applying modern processing algorithms to legacy seismic data results in improved structural resolution and more accurate delineation of deeper ore deposits (Manzi et al., 2018a, b).…”

Section: Introductionmentioning

confidence: 99%

Seismic imaging of the gold deposit and geological structures through reprocessing of legacy seismic profiles near Kloof–Driefontein Complex East Mine, South Africa

Mutshafa¹,

Manzi²,

Westgate³

et al. 2022

Geophysical Prospecting

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Two legacy reflection seismic profiles were acquired in 1988, north of the Kloof–Driefontein Complex East Mine in the West Rand goldfield (South Africa), for the purpose of gold exploration and mine planning. These legacy 2D seismic data have been reprocessed using the latest processing tools to improve imaging. Special interest is given to the Black Reef Formation, which hosts a known gold orebody. The original legacy data are of poor quality, especially in areas that are dominated by dolomitic outcrops. To improve the quality of the data, special attention was given to the refraction static correction to enhance the continuity of the reflections below dolomitic rocks. Refraction seismic tomograms from both profiles exhibit three‐layer P‐wave velocity models: (1) topsoil (1000–2000 m/s), (2) a weathered layer ranging from ca. 100 to 300 m in thickness (2000–5000 m/s) and (3) bedrock (> 5000 m/s). Seismic profile OK‐212 shows poor imaging of the Black Reef Formation because of the scattering of seismic energy in the near‐surface due to dolomites from the Transvaal Supergroup, while seismic profile OK‐213 exhibits south‐dipping reflections that are associated with the Black Reef Formation. To improve the structural imaging resolution, we tried pre‐stack time migration, pre‐stack depth migration and post‐stack time migration using the Kirchhoff algorithm. PreSDM most improved the imaging of deeper reflections due to its ability to honour complex lateral variations in the velocity field. Both pre‐stack time migration and post‐stack time migration enhanced the continuity of the near‐surface reflections below the dolomitic rocks.

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Reappraisal of Legacy Reflection Seismic Data for the Prospection of Iron Mineralisation

Cited by 3 publications

References 0 publications

Multi‐geophysical methods for characterizing fractures in an open pit mine, western Bushveld Complex, South Africa

Multi‐geophysical methods for characterizing fractures in an open pit mine, western Bushveld Complex, South Africa

A reappraisal of legacy reflection seismic data from the western margin of the Kaapvaal craton, South Africa, with implications for Mesozoic-Cenozoic regional tectonics

Seismic imaging of the gold deposit and geological structures through reprocessing of legacy seismic profiles near Kloof–Driefontein Complex East Mine, South Africa

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