Impact case study database

A metallogenic belt is typically formed by multiple geological events that have led to the Earth’s crust being endowed in metals that are associated with different formation mechanisms as well as ages. As such, for economic exploration, it is critical to establish the geological age of the metal (e.g., copper, gold, molybdenum) enrichment in the Earth’s crust that a company is targeting. Herein lies the power of the application of the Re-Os molybdenite chronometer based on Durham-led research [e.g., R1 – 6] and why companies such as Rio Tinto and MMG, as part of their exploration program want to establish the chronology of the mineral enrichment targeted in their exploration programmes . Commissioned through focused industry-based (Rio Tinto, MMG, Eldorado, Sun Metals – see below) research projects at Durham, Re-Os molybdenite ages (hereafter referred to as Durham-led Research - DLR) have provided critical data to evaluate exploration models. This allows mineral companies to devise accurate resource estimates and exploration programmes and save exploration expenditure and thereby reduce any industry-related environmental impact. Although due to confidentiality exact figures cannot be given, the total impact claimed here is worth hundreds of millions of US dollars.

In the cases discussed below, the impact has occurred since August 2013 and is on-going, as is the nature of impact with mineral exploration. Companies will not divulge the specific details of their explorations to maintain their competitive market position, but they have provided testimony that falls within the REF period.

*Rio Tinto and MMG Impact cases [E1, 2]

The DLR has provided Rio Tinto and MMG data that has permitted reassessment of mining activities and exploration in the REF period, respectively. The DLR has resulted in plans to increase the life of mine operations at one of the World’s major copper producers for another 20 years. This yielded a revenue of hundreds of millions of US dollars.

Both Rio Tinto and MMG are major explorers for porphyry-related copper reserves (supply ~75 % of the world’s copper) that typically also contain significant reserves of molybdenum and gold. Porphyry deposits are a major geological manifestation of where the Earth’s crust has been repeatedly intruded by small porphyry plutons that also channel metal-rich fluids, resulting in a local enrichment of metals (e.g., copper), with the younger events often overprinting the older events [R2 – 6 and industry-led research at Durham ], or occurred spatially close together (< a few kms) or at deeper crustal levels. Over the last decade, it has been shown that the youngest magmatic-hydrothermal event is typically the major carrier of the economic resource. As such, knowing the age of the sequence of the magmatic-hydrothermal events [R2 - 6] is of paramount importance in determining the likely economic value during preliminary exploration.

DLR Outcome 1 – During the REF period the MMG case highlights how the Re-Os molybdenite ages obtained by DLR have specifically aided in providing the understanding that the economic mineralisation occurred in a very short time interval (0.5 millions of years), and is only specifically related to one intrusion event (the youngest), although the prospect geology includes igneous activity that spans nine million years. This has benefited MMG by permitting the company to focus their exploration accordingly. The company state that, whilst it is difficult to put an absolute financial figure on the impact, direct savings in terms of drilling (USD 100,000 per drill hole – exploration at this scale involves 100+ drill holes) and time (e.g., mapping, assay analysis, geophysics, etc) had enormous impacts. Specifically: ‘ Constraining the timing / geological formation of metal enrichment is fundamental to not only the scientific understanding of how economic concentration of copper and molybdenum (Cu-Mo) form, but also to develop financially effective exploration programme and deposit models. The geological dating of the Mo bearing mineral molybdenite by the Re-Os radioisotope tool is the most accurate and precise methodology to achieve this, with the laboratory at Durham University led by David Selby being world leading in its development and application.’ Principal Exploration Geologist, MMG Las Bambas **[E1] .

DLR Outcome 2 - During the REF period, one case from Rio Tinto, at Escondida, Chile, highlights how DLR has permitted the company to restructure its mine site to access and maximise exploitation of the greatest endowment of copper in the region. In a development costing hundreds of millions of dollars, DLR has permitted the company to expand their exploration to locate the most economic concentration of copper. This will ultimately lead to revenues far exceeding the initial development expenditure for the company. The mine restructuring will result in an increase in the lifespan of the mining at Escondida yielding enhanced employment security for hundreds of Chileans and revenue for Chili. The Principal Geologist, at Rio Tinto states: ‘For Rio Tinto, the recognition of the value Re-Os molybdenite geochronology that is provided by Prof Selby at Durham University has changed the way in which we explore for resources over the last five years’ [E2].

Eldorado Gold Corporation Impact cases [E3]

For Eldorado Gold, DLR has aided in steering the company’s exploration program which runs in to CAD10sMillion.

DLR Outcome 3 - During the REF period, in Brazil, DLR identified an age that is genetically associated with the copper and not gold mineralisation. As Eldorado Gold is a gold-focused company, this allowed the company to re-evaluate their exploration program, which in this case, involved leaving the prospect area that, although economic for copper, was not economic for gold. This was an important decision as halting exploration resulted in savings that would have run into several millions of Canadian dollars (CAD). Chief Geoscientist, Eldorado Gold states : ‘The Re-Os molybdenite date allude to the fact that the molybdenite was genetically associated with the Cu-Mo system and not the gold-bearing IRGS system. This was critical in guiding our exploration in the region because as a gold-focused company the IRGS were the most attractive target and thus allowed the company to pull back on the Cu-Mo exploration. As a result, potentially saving several millions of dollars in exploration costs.’

DLR Outcome 4 - During the REF period, in Turkey, a Tertiary geological age has been established to be the key timing interval for gold mineralisation. The DLR has been critical in confirming or denying the age of gold-related mineralisation, which has as a result guided the company’s exploration programs where approximately CAD20million have been spent on exploration.

DLR Outcome 5 – Similarly during the REF period, in Greece, where the key geological ages are 33 to 23 and 23 to 5 million years ago, with the geological characteristics of each age of mineralisation being similar, the DLR has confirmed the timing of gold mineralization and directly guided the company’s exploration strategy that has a budget of up to CAD10million. The Chief Geoscientist, Eldorado Gold states: ‘We have used Re-Os dating of molybdenite on our prospects to determine which generation the mineralisation is related to, and the results have helped guide our exploration strategy in the region where we typically have an exploration budget of CAD5-10million.’

In summary, during the REF period, the outcome of DLR for several international mining companies working in several countries has provided critical data to strategically refine their exploration programs, and in one case revise the location of a principal mining site. Financially, this has permitted companies to maximise expenditure in terms of explorations that totals hundreds of USD and minimise environmental impact. Moreover, in the case of mine redevelopment, DLR has led to further security in terms of employment and country revenue.