Engineering & Mining Journal

JUN 2013

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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E X P LO R AT I O N Dynamic Earth Model Offers New Exploration Insights Miners looking deeper underground for new mineral deposits need better tools to reduce risk and identify favorable locations. Comprehensive digital subsurface models offer improved technology to accomplish both of those goals. By Simon Walker, European Editor According to Dr. Graeme Nicoll, head of the minerals exploration group at the U.K.-based earth-science research company, Neftex, as the number and quality of new mineral deposit discoveries continue to decline, miners are being forced deeper into the subsurface realm to access mineral wealth. This, he said, then exposes the sector to greater risk and financial uncertainty. While the tools and technology for accessing and exploiting subsurface deposits are advancing, Dr. Nicoll explained, identifying the right location to explore is increasingly becoming more of a challenge. New tools are therefore required that will identify subsurface or "blind" deposits, and offer a predictive model to increase discovery and exploration efficiency. Since its inception, plate tectonics has underpinned concepts that explain the global distribution of economic minerals and inform where new deposits are likely to be found. Detailed and large scale "earth models", built around plate-tectonic ideas, have traditionally been pioneered by the oil industry to better understand the temporal and spatial distribution of source, reservoir and seal rocks. These models involve gathering both surface and subsurface data (geological maps, satellite images, geological interpretations, geophysics, well logs and so on) and combining them, in one digital platform, into fourdimensional models (3-D plus time). Transferring the Concept to Minerals From its headquarters near Oxford in England, Neftex is at the forefront of developing an integrated earth model (Figure 1). The company specializes in the collation, integration and interpretation of large geoscience datasets, and in delivering these as digital subsurface models. These products and services provide a comprehensive picture of subsurface geology, thereby helping to reduce risk and increase value across many sectors, including mining, petroleum and finance. Neftex has developed and delineated a global array of Geodynamic Units (GDUs)—individual pieces of the Earth's crust that record unique geological histories. Building on a previous plate-tectonic research program at the Université de Lausanne in Switzerland, the model is constantly undergoing refinement, Dr. Nicoll said. An example is the recent addition of more than 2,000 oceanic crust segments, the definition of intracratonic boundaries for crustal assembly back to 2.5 billion years, and the identification of zones of attenuated continental crust. The Neftex Geodynamic Earth Model is a sophisticated global plate model that currently allows reconstruction of any form of spatial data between the present day and 595 million years ago. The model is internally consistent and is supported by the company's unique understanding of global stratigraphy and tectonics. Modeling Geological History The earth model provides the ability to track and delineate major collisional events, subducted margins, major volcanic-arc activity, large igneous intrusive events and the Phanerozoic redistribution of mineral-rich Archean terranes. As the earth model is global, it is possible to relate mineralizing activity in one region and directly compare it with another. This, Dr. Nicoll explained, adds greater insight to the process, and Figure 1— Example of the range of data types that go into the Neftex Earth Model. (All photos © Neftex) 80 E&MJ • JUNE 2013

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