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- Cheraghi, Saeid, et al.
(författare)
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Reflection seismic imaging across a greenstone belt, Abitibi (Ontario), Canada
- 2023
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Ingår i: Geophysical Prospecting. - : John Wiley & Sons. - 0016-8025 .- 1365-2478. ; 71:7, s. 1096-1115
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Tidskriftsartikel (refereegranskat)abstract
- Established 2D seismic data processing methods such as Kirchhoff pre-stack time migration and Kirchhoff pre-stack depth migration function relatively well for regular acquisition geometries and well-constrained velocity models. Recently developed focusing pre-stack depth migration methods have the potential to enhance image quality in the case of sparse and non-regular source-receiver distribution. We have tested the performance of the coherency migration method as one of these focusing migration approaches in comparison to standard dip-moveout and Kirchhoff pre-stack time migration techniques by applying them to the Swayze East seismic profile acquired in the Abitibi greenstone belt of Canada. This seismic profile represents a crooked-line survey that intersects several metal-bearing deformation zones, providing good target geometries to examine various pre-stack migration methods. Analysis of the seismic data indicates reflectivity associated with shallowly dipping reflections appears relatively well preserved over the entire 0-6 km offset range for the frequency range between 20 to 90 Hz. Although most reflections are visible already in either the dip-moveout or the Kirchhoff pre-stack time migration results, the coherency migration method delivers the most improved image showing all reflective structures inferred for this area. The comparisons suggest the coherency migration method can be considered as superior in terms of resulting seismic image quality compared with conventional approaches for this type of crooked-line seismic survey in such a complex geological setting.
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| 2. |
- Hlousek, Felix, et al.
(författare)
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Three-dimensional reflection seismic imaging of the iron oxide deposits in the Ludvika mining area, Sweden, using Fresnel volume migration
- 2022
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Ingår i: Solid Earth. - : Copernicus Publications. - 1869-9510 .- 1869-9529. ; 13:5, s. 917-934
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Tidskriftsartikel (refereegranskat)abstract
- We present pre-stack depth-imaging results for a case study of 3D reflection seismic exploration at the Blotberget iron oxide mining site belonging to the Bergslagen mineral district in central Sweden. The goal of the study is to directly image the ore-bearing horizons and to delineate their possible depth extension below depths known from existing boreholes. For this purpose, we applied a tailored pre-processing workflow and two different seismic imaging approaches, Kirchhoff pre-stack depth migration (KPSDM) and Fresnel volume migration (FVM). Both imaging techniques deliver a well-resolved 3D image of the deposit and its host rock, where the FVM image yields a significantly better image quality compared to the KPSDM image. We were able to unravel distinct horizons, which are linked to known mineralization and provide insights on their possible lateral and depth extent. Comparison of the known mineralization with the final FVM reflection volume suggests a good agreement of the position and the shape of the imaged reflectors caused by the mineralization. Furthermore, the images show additional reflectors below the mineralization and reflectors with opposite dips. One of these reflectors is interpreted to be a fault intersecting the mineralization, which can be traced to the surface and linked to a fault trace in the geological map. The depth-imaging results can serve as the basis for further investigations, drilling, and follow-up mine planning at the Blotberget mining site.
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