Seismic signatures of complex geological structures in the Cue-Weld Range area, Murchison domain, Yilgarn Craton, Western Australia

Ahmadi, Omid; Koyi, Hemin; Juhlin, Christopher; Gessner, Klaus

doi:10.1016/j.tecto.2016.02.020

Cited by 4 publications

(3 citation statements)

References 31 publications

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“…Intrabasement seismic reflectivity, such as that identified and mapped by Fazlikhani et al (2017), may be the result of compositional and structural heterogeneities within the crust, and the type and amount of ductile and brittle deformation that an area experienced (e.g., Smythe et al, 1982;Jones and Nur, 1984;Wang et al, 1989;Goff and Holliger, 2003;Smithson and Johnson, 2003;Meissner et al, 2006;Bongajum et al, 2012;Ahmadi et al, 2016;Hedin et al, 2016). Although intrabasement structures have been described from regional, deep-imaging 2-D seismic reflection profiles (e.g., Wang et al, 1989;Allmendinger et al, 1987;Kern and Wenk, 1990;Reston, 1996;Cook et al, 1999;Abramovitz and Thybo, 2000;Juhojuntti et al, 2001;Simancas et al, 2003;Torvela et al, 2013;Ruiz et al, 2017), few studies use borehole data (e.g., Christensen and Szymanski, 1988;Zhang et al, 2005;Hedin et al, 2012Hedin et al, , 2014Hedin et al, , 2016Lorenz et al, 2015), synthetic seismogram modeling (e.g., Fountain et al, 1984;Hurich et al, 1985;Reeve at al., 2014;Phillips et al, 2016;Kennett et al, 2017;Veludo et al, 2017), and/or gravity and magnetic forward modeling (e.g., Ebbing et al, 2006;Ritzmann and Faleide, 2007;Marello et al, 2010;Gernigon and Brönner, 2012;…”

Section: Introductionmentioning

confidence: 99%

Structural architecture and composition of crystalline basement offshore west Norway

et al. 2019

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Numerous studies have investigated the geodynamic history and lithological composition of the Proterozoic basement, Caledonian nappes, and Devonian extensional basins and shear zones onshore west Norway. However, the offshore continuation of these structures, into the northern North Sea, where they are suspected to have influenced the structural evolution of the North Sea rift, is largely unknown. Existing interpretations of the offshore continuation of Caledonian and Devonian structures are based on simple map-view correlations between changes in offshore fault patterns and pronounced onshore structures, without providing evidence for the presence, nature, and geometry of offshore, basement-hosted structures. By integrating three-dimensional (3-D) seismic, borehole, and onshore geological and petrophysical data, as well as two-dimensional (2-D) forward modeling of gravity and magnetic data, we reveal the structural architecture and composition of the crystalline basement on the Måløy Slope, offshore west Norway. Based on 3-D mapping of intrabasement reflection patterns, we identified three basement units that can be correlated with the Caledonian thrust belt, and the major Devonian Nordfjord-Sogn detachment zone, located only 60 km to the east, onshore mainland Norway. Similar to that observed onshore, offshore crystalline basement of the Proterozoic basement (Western Gneiss Region) and allochthons is folded into large-scale antiforms and synforms. These units are separated by the strongly corrugated Nordfjord-Sogn detachment zone. Our analyses show that different types of crystalline basement can be distinguished by their seismic reflection character, and density and magnetic properties. We speculate that the main causes of the observed intrabasement reflectivity are lithological heterogeneities and strain-induced structures such as shear and fracture zones. Our interpretation of the architecture of crystalline basement offshore west Norway has important implications for the location of the suture zone between Baltica and Laurentia.

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Section: Introductionmentioning

confidence: 99%

Structural architecture and composition of crystalline basement offshore west Norway

et al. 2019

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“…The modelling was conducted using Tesseral Pro software. Figure 4 shows the geological model built (Ahmadi et al ., 2016; Singh et al ., 2020) from borehole data and mine information (Fig. 2).…”

Section: Physical Property Measurementsmentioning

confidence: 99%

Cost‐effective in‐mine seismic experiments to image platinum deposits and associated geological structures at Maseve platinum mine, South Africa

Rapetsoa

Manzi

Westgate

et al. 2022

Near Surface Geophysics

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The detection of mineral deposits and their related geological structures is of great importance to the mining industry as structures (such as dykes and faults) can affect the safety, cost and efficiency of mining. With the goal of testing cost-effective seismic methods for mineral exploration and mining, active and passive seismic experiments were conducted at Maseve platinum mine in the Bushveld Complex (South Africa) in 2020. The experiments involved surface-passive (using 5 Hz wireless nodes; single vertical component) and in-mine active reflection seismic surveys (using 4.5 Hz land streamer and 5 kg sledgehammer) to image geological structures and delineate economic platinum-group elements bearing Merensky and Upper Group-2 chromitite layers (known as reefs). This paper presents only the results from the in-mine active seismic experiments. The in-mine seismic surveys consisted of seven 2D reflection seismic profiles in the development tunnels, which were located ∼550 m below ground surface and a few tens of metres above known mineralizations: the Upper Group-2 and Merensky Reef. The data were carefully processed to enhance the reflections and suppress noise generated by mine infrastructure (e.g., equipment and ventilation). We successfully imaged the Merensky Reef and Upper Group-2 orebodies approximately 55 m and 124 m below the tunnel floor, respectively, and delineated faults and dykes that crosscut them. Furthermore, the seismic data reveal relatively strong amplitude and faulted reflections below the Upper Group-2 that may represent deeper chromitite-enriched orebodies. However, the economic value of these horizons can only be confirmed through drilling. The processed seismic data were combined with borehole data, synthetic modelling and geological models to constrain the interpretation. This study encourages the use of in-mine seismics for future mineral exploration, mine development and planning.

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“…3b). There is a wide range of successful applications of this approach in hard rock environment (e.g., Ahmadi et al, 2016 and references therein).…”

Section: Legacy 2d Seismic Data and 2d Seismic Modellingmentioning

confidence: 99%

Seismic delineation of the gold‐bearing structures in the South Rand goldfield (South Africa): A comparison of pre‐stack time and depth migration approaches on legacy seismic data

Sihoyiya

Manzi

James

et al. 2022

Near Surface Geophysics

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To better image complex geological structures and explore for the gold-bearing quartz pebble conglomerate (locally termed Kimberley Reef) near Burnstone mine in the South Rand goldfield (South Africa), we reprocessed legacy 2D reflection seismic data using up-to-date seismic processing algorithms. The mining region is dominated by steeply dipping normal and reverse faults, as well as dolerite intrusions that crosscut the tabular gold mineralization and complicate the extraction of the ore. The legacy seismic data were acquired in 1993 in the South Rand goldfield as part of the gold exploration programme by the Gold Division of Anglo-American Corporation. The pre-stack data quality was improved by cautiously removing noise and applying static corrections to enhance the continuity of the reflection events. Improved structural imaging was then achieved using pre-stack time migration and pre-stack depth migration through careful velocity analysis. In particular, pre-stack depth migration provided better imaging of near-surface stratigraphic units and deep-seated complex structures, relative to older post-stack migrated images produced in 1993. Other reprocessing improvements included accurate imaging of key seismic reflective interfaces that can be used as proxies to 2D map the gold deposit, its dip variations, and geological structures (faults/dykes) crosscutting it. Synthetic shot gathers data computed using a 2D finite-difference algorithm provided some insight into the source of seismic reflectivity observed on the reprocessed seismic data. The new structural information from reprocessing is essential for enhancing ore resource evaluation and guiding future exploration projects in the region.

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Seismic signatures of complex geological structures in the Cue-Weld Range area, Murchison domain, Yilgarn Craton, Western Australia

Cited by 4 publications

References 31 publications

Structural architecture and composition of crystalline basement offshore west Norway

Structural architecture and composition of crystalline basement offshore west Norway

Cost‐effective in‐mine seismic experiments to image platinum deposits and associated geological structures at Maseve platinum mine, South Africa

Seismic delineation of the gold‐bearing structures in the South Rand goldfield (South Africa): A comparison of pre‐stack time and depth migration approaches on legacy seismic data

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