by Dr Ian Basson and Dr Corné Koegelenberg, Principal Members and Michael McCall, Senior Geoscientist
Tect Geological Consulting (Tect) is an industry-leading specialist in Structural- Economic Geology with well-established experience across the world, and a particular focus on Africa and the Middle East. Over the last 22 years, Tect has addressed over 180 projects in the mining, exploration and investment industries, building longstanding, value-driven partnerships focused on comprehensive and sustainable structural data collection, analysis and interpretation. The outcomes of these projects are robust, fully-constrained, fit-for-purpose, 3D geological models that are used in various Geotechnical, Mineral Resource Management (MRM), Mine Planning and Geohydrological applications. Such models are paramount to de-risking and optimizing projects.
Company history and development
Over two decades ago, Tect undertook detailed structural mapping and 3D geomodelling at Rössing Uranium Mine in Namibia and De Beers’ Venetia Mine in South Africa. Since then, Tect’s philosophy of careful, high-resolution mapping, structural interpretation, data custodianship and advanced, best-practice 3D geomodelling has resulted in over 100 fully-constrained 3D models of major structures, country rock and orebody geometries, alteration zones, fracture domains and bedding/ foliation domains. Although the core of our business is in Africa and the Middle East, Tect’s Associate Consultants and Associate Researchers have consulted on mining projects in Bosnia, Brazil, Canada, Ecuador, Finland, India, Kazakhstan, Malaysia, Portugal, Spain, Sweden, Vietnam and Australia. Recently, two experienced Structural Geologists were added to the list of Tect’s Associates: Dr Brett Davis and Prof. Alex Kisters. Howard Baker, who is a Mineral Resources Specialist, and Damian Smith, a PGE specialist, joined our Associate group a few years ago.
Tect’s high-quality 3D models have been developed for most of the super-pits and large underground operations in southern Africa, including Venetia, Jwaneng, Orapa, Voorspoed, Cullinan, Letlhakane, Damtshaa, Sishen, Kolomela, Thabazimbi, Mogalakwena, Northam, Lonmin, Amandelbult, Booysendal, Waterberg/PTM, Rössing, Chimiwungo, KOV, Mutanda, Kansanshi, Lubambe, Frontier, Palabora and, in the Middle East, Miduk and Gol-e-Gohar. Tect has also resolved the geometries of underground precious metal mines and exploration projects, including recent, very successful projects such as Bisie, Wassa, Blanket, Mopani, Bibiani, Shanta, Osino and Xtra-Gold. More information on these and other projects may be found at www.tectgeological.com
Back to basics
High-quality mapping data underpins any structural and lithological interpretation. Tect undertakes direct surface and underground mapping, accompanied by the characterization of structural and lithological features, using the latest mobile GIS platforms and differential GPS systems. These datasets are combined with quality-controlled mapping data from the Client, high-density photogrammetry and LIDAR surveys and colorized or false-colorized point cloud surveys, to delineate structures and lithological contacts. Additional data sets comprise downhole data, such as OTV/ATV and the data from oriented core logging. With a focus on resolving the structural evolution of the volume of interest, attention is paid to all features: lithology, alteration, mineralization and fabrics, in addition to more regional geophysical and remote sensing datasets. Structural features are characterized according to their surface geometry, fill, aperture and other parameters as required by Geologists, Geotechnical Engineers and Geohydrologists for their downstream analysis, modeling and forward-planning.
Each Project Leader takes custody of the entire value chain, from mapping and data-mining, through background research and structural interpretation, to workshops, reporting and handover. This is one of the ways that Tect distinguishes itself from most of the larger geological consulting firms. Customized, project-specific Standard Operating Procedures that describe these workflows form part of the deliverables, with a view to handing over data and model upkeep to the Client’s technical team.
Tertiary analysis: Post-processing for geotechnical design
The integration and representation of relevant, scaled geoscientific data is translated into dynamic 3D implicit models, primarily aimed at bridging the gaps between Geology, Geohydrology, Geotechnical Engineering, Resource Estimation, Mine Planning and Exploration Departments. Tect uses a combination of Leapfrog Geo and Micromine, with solution- and data-specific modeling methodologies. Assessing and quantifying the interaction of geological features represented in fully-constrained, implicit 3D geological models (bedding, foliation, contacts, faults and fracture/joint domains) with a mine design or Whittle Shell, is essential for forward Geotechnical design and planning. This process is often, however, understated or oversimplified and companies resort to radial, section-based analysis which suffers from numerous limitations. Tect utilizes mainstream software packages, and customized, proprietary scripts in MATLAB and Python 3 to extract and quantify the way in which these features interact with the pit or design surfaces, thereby allowing apparent dip and conditional shear-failure to be calculated as spatially-continuous parameters. The results of these analyses, which Tect pioneered and implemented for Venetia Mine in 2015, allow for the definition of 3D structural-geotechnical domains that are translatable into Geotechnical block models. This methodology has now been adopted at Jwaneng, Kolomela, Mogalakwena, KOV and Chimiwungo, providing the Mining and Geotechnical teams with a robust tool for the prediction of areas that might react adversely to mining or which need closer monitoring.
Another development that Tect has been closely involved in is 3D modelling for the prediction and quantification of palaeosinkholes. Using a workflow that is very similar to Weights-of-Evidence or Model-Driven approaches in the exploration industry, Tect has successfully predicted the position, size and depths of karstic palaeosinkholes within mining volumes using 3D spatial queries.
What about exploration?
Structural geology and the understanding of kinematics as applied to fluid movement and mineralization is one of Tect’s fortes. In collaboration with partners, New Resolution Geophysics, Xpotential and Remote Exploration Services, quantitative modeling and inversion, across a range of Geophysical methods has been undertaken, subject to the availability, quality and coverage of data. This created fully-integrated, shared-earth models, incorporating all data sets in 3D and thereby providing a more rigorous targeting process. Over 80 Geophysical interpretation projects, of varying complexity, have been undertaken to date.
Basic products include an interpretation of ductile and brittle structures, and geophysical domaining. First-pass proxy geological maps, generated from these geophysical domain maps, are generated by ground-truthing and integration with other geological data. This enables units to be targeted, often with the inclusion of soil Geochemistry, to test one or a series of mineralization models. More advanced targeting studies, involving Weights-of-Evidence and Model-Driven approaches have been applied to IOCGs, IOAs, Birimian-style and orogenic/lode Gold, Copper-Cobalt, Iron-Manganese, Carbonate-replacement and Mississippi Valley-Type Lead-Zinc projects in Africa and the Middle East.
There are not many groups of Structural-Economic Geologists that publish their work in peer-reviewed international journals. Tect has a strong focus on putting our work out there, in the form of topical, data-driven articles that are co-authored by our Client’s Geologists and Geotechnical Engineers. To date, Tect Geoscientists and Associates have published in excess of 120 papers on structural and economic geology, which are viewable and available on request by contacting us via our website. The formulation of papers, as a team, has a beneficial spin-off: Tect’s standard and quality of reporting are recognized as being industry-leading.
As part of our services, Tect provides Due Diligence and Structural Audits, Exploration Geoscience Management and Regional Data Compilations. In collaboration with Ken Lomberg of Pivot Mining and Howard Baker, we have worked on numerous CP/QP reports, developing accurate 3D models that are fed into this process. The recent successes of Shanta Gold, Blanket Mine, Goldenstar/Wassa, Alphamin/Bisie and Chesser Resources speak for themselves. During the evolution of Tect, we have also branched off into UAV surveys via a new company, Geoflight (see www.geoflight.co.za). Lastly, by way of establishing the regional context of the projects we have worked on, we have compiled an African-wide, interrogable, spatial database of geological features, derived from open-source data. This is hosted and showcased at www.geopoint.co.za.
While consulting, we get an idea of what Clients want in terms of training. To this end, we have developed three courses, which we routinely provide to Clients, to the Geological Society of South Africa’s Directorate of Professional Programs (DPP) and to Universities in South Africa. The first of these is 3D Geomodelling, which is a 16-module course. In order to confidently use 3D models for downstream processes, such as mine design, Mineral Resource Estimation and Geohydrology, an understanding of the parameters used in their construction is essential. The course describes model inputs, validation, verification and common pitfalls. It explains the recent shift from explicit, section-based, geometrical modelling to attribute modelling, to rules-based, implicit modelling, such as that employed by Leapfrog. Such insight is particularly useful for Geoscientists that represent companies that are looking to change their geomodelling software.
The request for a refresher course on Structural Geology from industry professionals frequently arises. Although Structural Geology is an often-intimidating university course, it’s a discipline that is routinely required in mapping, data gathering and interpretation of prospects and deposits. It is therefore worth keeping up with the topic and with new developments. The course consists of 12 modules, covering tectonics, fabric, strain, stability, Mohr diagrams, cataclasis, rheology, application to ore fluids, application to petroleum systems, mylonites, ductile shear zones, shear criteria, kinematic indicators and SPO/CPO/LPO fabrics. The course is particularly useful to Geoscientists that require a refresher on the subject, who are interested in topics that were not covered in undergraduate courses or for those that are interested in the application of Structural Geology to mineralization and 3D modeling.
Tect has, in collaboration with Seequent/Bentley, the distributors of Leapfrog, developed a Leapfrog Masterclass. This is a 3-day course comprising 11 modules focused on resolving structurally-complex geology in Leapfrog. This uses comprehensive real-world datasets in a variety of structurally-complex geological environments. The interactive course covers Leapfrog’s advanced 3D modeling tools. Focus is placed on structural geology and multiple data types to derive realistic geometries. Practical exercises provide users with a hands-on introduction to advanced modeling techniques, guided by best-practice principles and strategies employed by experienced Structural-Economic Geologists. For more information, please see www.tectgeological.com.
The Tect team and partners
Geoscientists: Dr Corné Koegelenberg, Dr Ian Basson, Ben Stoch, Michael McCall, Jonathan Gloyn-Jones, Heike Fourie, Luke Carlton and Caitlin Jones.
Associates: Dr Brett Davis, Prof. Alex Kisters, Dr Pieter Creus, Dr Jodie Miller, Howard Baker and Damian Smith.
Partners – Itasca, Seequent, Micromine, New Resolution Geophysics, Xpotential, Remote Exploration Services, Pivot Mining Consultants, Incaic Exploration SPA
2022 and beyond
The trend is for newly-discovered prospects and deposits to be deeper and more structurally complex. Getting the geometries of these prospects and deposits correct is becoming increasingly crucial. If the geometry of the orebody that is fed into the Mineral Resource Modelling process is incorrect, then the estimation is necessarily incorrect. Similarly, if the geometry of the ore body, country rocks, major structures and rock fabrics is not accurate or sufficiently representative, undesirable and unexpected events will occur during mining. Tect, along with its Associates and industry-leading partners, will continue our tradition of carefully constructing the best 3D geomodels for the mining and exploration industry.
For more information visit: www.tectgeological.com
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