Geology and Discovery History of the Money Knob Gold Deposit, Tolovana Mining District, Eastern Alaska
Jeffrey Pontius, Russell Myers, Chris Puchner, 2010. "Geology and Discovery History of the Money Knob Gold Deposit, Tolovana Mining District, Eastern Alaska", The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, Richard J. Goldfarb, Erin E. Marsh, Thomas Monecke
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The Money Knob deposit is a major new, bulk-tonnage, gold discovery located 110 km northwest of Fairbanks, Alaska, within the Tintina gold belt. The deposit was discovered in 2007 and by the end of 2009 contained a combined indicated and inferred resource of 389 metric tons (t) of gold at a grade of 0.85 g/t gold using a 0.5 g/t gold cutoff grade. Gold mineralization is hosted within a fold and thrust sequence of Cambrian and Devonian rocks intruded by 90 Ma dikes and sills, which are contemporaneous with the main-stage gold event. Gold mineralization occurs as shallowly dipping, east-west–trending, tabular bodies within permeable sedimentary and volcanic rocks, with higher grade zones related to north-northwest–trending crosscutting structural zones.
The discovery of the Money Knob deposit evolved from a series of exploration programs conducted by eight different companies during a 30-year-long period. An examination of the successes and failures during the exploration history outlines three key concepts that were important in the discovery: (1) the need to operate with multiple, working exploration models that are driven by high-quality data and observations; (2) recognition that large mineral systems are rare and should be fully evaluated in light of potential long-term changes in commodity price, technology, and deposit characteristics; and (3) successful exploration requires a champion and a talented team with vision and perseverance.
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The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries
There seems to be general consensus throughout much of the global mining industry that the supply of base and precious metals and some other commodities (e.g., ferrous metals, uranium) is reasonably well assured into the oreseeable future because increases in total resources continue to keep pace with or outstrip global consumption. The basic assumption is that market forces and technological advances will combine to promote and perpetuate this trend (e.g., Tilton, 2003; Crowson, 2008). Others disagree, however, andpredict that shortages are inevitable if metal consumption continues to escalate (Beaty, 2010).
It is already becoming clear that many known resources seem unlikely to be mined, irrespective of commodity prices, because of their low grade and/or quality. Hence, many mineral resources that were uneconomic in the early 2000s are likely to remain so, both today and into the foreseeable future because of increases in both the direct (e.g., energy, labor) and indirect (e.g., environmental, social) production costs. This situation is being further exacerbated by the perceived decrease, over at least the past decade, in the discovery rate of base and precious metal resources measured in terms of both the number of major discoveries made and the exploration dollars spent per discovery (e.g., Dummett, 2000; Horn, 2002; Schodde, 2004). There is also a suggestion that the discoveries made are, on average, becoming both smaller and lower grade. Therefore, it seems reasonable to ask whether current exploration practices and success rates are going to be adequate to provide for the massive increases in metal consumption that world population growth, rising living standards, and rapid industrialization and urbanization in China, India, and other emerging markets appear to portend. For example, Rio Tinto's projections suggest that "by 2030 the additional supplyrequired will be equivalent to replicating the iron ore output of the Pilbara region of Australia every five years, adding another aluminium production complex the size of Canada's Saguenay every nine months, and developing another copper mine the size of Escondida in Chile each year. Future energrequirements are such that an entire Hunter Valley coal supply chain needs to be created each year plus a uranium mine the size of Ranger every four years" (Albanese, 2010, p. 7). Clearly, the exploration business has to become increasingly effective if it is to rise to the challenge of finding mineral resources of the right caliber to assure that this burgeoning demand can be adequately satisfied.