Changes in Mineral Exploration Practice: Consequences for Discovery
Richard H. Sillitoe, John F. H. Thompson, 2005. "Changes in Mineral Exploration Practice: Consequences for Discovery", Wealth Creation in the Minerals Industry: Integrating Science, Business, and Education, Michael D. Doggett, John R. Parry
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This paper reviews and analyzes the role played by changes in mineral exploration practice on the discovery record worldwide, over a timeframe of roughly the last 50 years. Geologic field methods have remained relatively unchanged, although general geologic theory as well as some empirical and genetic ore deposit models and related concepts have undergone major revisions that have had significant but unquantifiable effects on the exploration process. The principal geochemical and geophysical methods employed in the 1950s and 1960s remain preeminent, notwithstanding the burgeoning sophistication of analytical techniques and geophysical instrumentation, and the exponential increases in data-processing capacity. Remote sensing and data management and modeling technology have also both advanced apace over the last two decades. The evolution of these earth-science disciplines affected the practicalities of mineral exploration in various ways, as demonstrated using porphyry Cu, volcanogenic massive sulfide (VMS), sediment-hosted (Carlin-type) Au, epithermal Au, orogenic (mesothermal) lode Au, and magmatic Ni-Cu deposits as examples, although constancy in search procedures prevailed over radical change.
Advances in the geologic, geochemical, geophysical, and remote-sensing fields do not seem to have greatly influenced the discovery record, at least where the most reliable compilations are available, for the circum-Pacific region over the last 35 years. Discovery has resulted mainly from routine fieldwork complemented by conventional geochemistry, and to a far lesser degree, from ground geophysics. Nevertheless, geophysics has made a greater contribution to discovery of the increasing number of deposits concealed beneath pre- and postmineralization cover. In Precambrian shield areas, such as Canada, Australia, and Scandinavia, with a dominance of different ore deposit types and distinct physiographic conditions, airborne geophysics has clearly played a more influential role in discovery, particularly of VMS, magmatic Ni-Cu, unconformity related U, and diamond deposits as well as greatly contributing to regional geologic understanding.
Perpetuation of broadly the same exploration approach, using tried-and-tested field-based methods, is strongly advocated, especially in the case of green-field programs. Continued innovative exploration of the world’s premier metallogenic belts and provinces must be combined with search for new, highly endowed frontier regions. While geologic and geochemical modeling remains vital for brown-field exploration, a greater future role for geophysics and grid and fence drilling is envisioned. Technologic advances in all these fields will undoubtedly facilitate an increasing number of exploration tasks, particularly data gathering, handling, and analysis, but are thought unlikely to dramatically change the discovery process and could even have a negative influence if not used to enhance productive field time. Future exploration success, especially under deep cover, demands more predictive ore deposit models and geochemical and geophysical methods that are better able to penetrate the overburden. The overall quality and inventiveness of exploration programs must improve, however, if the perceived decline in discovery rate and rise in discovery cost are to be remedied. Carefully targeted research on all fronts is necessary and should be welcomed.
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Global political and economic developments shape both the demand for minerals and primary metals and their supply. Overall, demand has moved broadly in step with economic activity over the past 30 years. Notwithstanding the collapse of the Soviet Union and Eastern Bloc countries, demand grew more rapidly in the second half of the period than the first. The performance of individual products within this general trend largely reflects the specific nature of their main end uses. The geographic center of demand has shifted away from the mature industrial economies of North America, Western Europe, and Japan toward the newly industrializing countries of the Pacific Rim, China, and India. Mine production rose with demand, but not always in precise step. New capacity was required not just to meet demand, even where that was static, but also to offset the continuing effects of ore depletion. There were also changes in the location of production in response to geopolitical forces, the depletion of ore reserves, and the changing economics of extraction and processing. The number of mines contracted, especially during the 1990s, and the scale of mining operations was increased in order to achieve the requisite cost savings. Prices fluctuated in response to changing balances between supply and demand, trending downward from the early 1970s until the early 2000s. Most products witnessed at least one sharp price spike during the period, usually with continuing repercussions. Prices picked up from 2003, but generally not back to their earlier peak in real terms. Profitability varied according to the products concerned. In many years the average rates of return on capital employed have been insufficient to cover the risks involved.