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Exploration for Mineral Deposits – Global Trends

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Exploration for Mineral Deposits – Global Trends news Exploration Geology Exploration for mineral deposits – global trends No. 47 SRK Consulting’s International Newsletter Standing on an undeveloped iron ore deposit, Pilbara, WA, with the Brockman Formation forming the Hamersley Ranges in the background Measuring the effectiveness of geological exploration and looking for trends that will lead to improved exploration success are key drivers for continued investment in the exploration industry. Expenditure on exploration in Australia, for example, This decreasing discovery rate is reflected in reached a peak in 2008, which reflects a massive Australia strongly focused on brownfields drilling, increase in exploration for iron ore resources and, with 63% of expenditure on those targets. to a lesser extent, coal resources. The correction While the latest trends show a slight increase after the global financial crisis in late 2008 resulted in greenfields exploration, the overall trend in a significant drop in 2009 – up to 42% globally, shows a continuing focus on areas with a higher most of which was recovered in non-ferrous mineral probability of success. exploration expenditures in 2010. With respect to greenfield exploration, the The Australian Bureau of Statistics report on industry is moving from a phase of discovery of current trends shows continuing strength, but the near-surface deposits to generating methods for return on expenditure on new deposits has been discovery of deposits at depth, either below an disappointing. Geoscience Australia identifies only unconformity or within a basement terrane, but one gold discovery, three base metal discoveries with no exposure at surface. and one molybdenum discovery from 2008-2010. …continued 1 Exploration for mineral deposits (continued) Both areas present significant SRK remains at the forefront of providing exploration challenges if the cost high-quality support to exploration of discovery is to remain within companies active in both brownfields economic bounds. and greenfields exploration. Search for deep or buried deposits relies on exploration targeting from geophysical PETER WILLIAMS datasets or specialised geochemical datasets by applying quality structural geology to geological interpretation of Peter has over them. Geological analysis remains a key 40 years experience component of greenfields exploration in the minerals support, and detailed mapping and industry, including advanced visualisation of structural 18 years as a data applied to brownfields or resource consultant on a expansion projects can add significantly range of projects to success. Particularly in brownfields, from project reviews advances in 3D modelling significantly and audits and enhance the probability of success and public reporting, to structural studies capability in designing drill programs on both a regional and orebody scale. based on geophysical and structural He has conducted major interpretation targets. Applying new modelling and projects from aeromagnetic data for visualisation techniques is at the core of exploration targeting, and has worked this competency. in a range of geological terranes in Australia, West Africa, East Africa, This newsletter provides case studies Zimbabwe, Zambia, Democratic Republic where SRK has contributed significantly, ining and exploration in Indonesia of Congo, Indonesia, Papua New Guinea, delivering discovery efficiently and M present challenges that are technical, Vanuatu, Solomon Islands and Europe. improving exploration success in an exploration environment that is legal and social in nature. The country Peter Williams: [email protected] increasingly technically challenging. is currently developing regulations for its new mining law, so there is some Peter Williams: [email protected] uncertainty, albeit within a well-defined legal framework. Indonesia provides numerous opportunities for exploration, and SRK *Mineral Exploration *Metres Drilled is currently involved in several major Seasonally adjusted and trend series Original series projects there, mainly concerned with preparing JORC resource statements on coal, gold, laterite nickel and $m copper deposits. This active tectonic Seasonally Adjusted 1000 New deposits 2000 Trend Existing deposits environment with volcanic arcs from 800 1500 the Cretaceaous to Recent periods 600 overlying Late Paleozoic to Mesozoic 1000 400 basement rocks, contain some world 500 class orebodies. 200 0 0 Asia Minerals Corporation recently Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun 2003 2005 2007 2009 2011 2003 2005 2007 2009 2011 engaged SRK Indonesia to assess the potential of small manganese deposits in Nusa Tengara Timor (NTT) in West * Source: Australian Bureau of Statistics, September 2011 Timor to feed a proposed new, local processing facility to comply with the new mining law. This will require a resource of about 2.5 million tonnes. 2 Indonesia – exploration on the cusp of development Typical bedded manganese deposit and artisanal extraction techniques, West Timor (above); Massive chert manganese breccia deposits, unconformity related, with local owners, West Timor (left) The opportunity is significant; Developing exploration skills employed and where geometry is there are more than 50 known either known or can be reasonably In collaboration with geologists from manganese sites in NTT, where the inferred. The results from testing Asia Minerals Corporation and other ore is currently extracted by artisanal these techniques will guide future advisors, SRK hosted a workshop in mining techniques and exported as program development. Jakarta to advance the understanding of unprocessed product. manganese deposits and generate an SRK will continue its involvement The individual deposits are small, exploration program that would address through field reviews, regular spread across extensive areas. Several the physical and climatic aspects of exploration program audits, and economically-viable, near-surface NTT in West Timor and provide the assessment of exploration results. deposits are commonly pursued highest probability of success in Over a 2-day workshop, Asia Minerals concurrently to provide sufficient defining manganese deposits to about Corporation learned about the key tonnes for processing. The advantage 50m depth along strike from known data collection required to assess is that deposits are generally high- occurrences. current exploration areas and generate grade with low impurities. The workshop identified and mapped exploration models, adopted a The key to discovering and those occurrences, and prioritised methodology to assess the entire exploiting such deposit fields is in them for field inspection. The mapping eastern NTT region for exploration understanding the deposit genesis for program outlined criteria and methods potential, and an immediate program targeting, and following a disciplined to determine the characteristics of to assess its current development exploration methodology. In Timor, the the deposits and to help develop a licence for preliminary resource deposits are located in sedimentary genetic model for NTT manganese. It estimation. In the process, it rock deposited on the seafloor, identified remote sensing requirements, gained a committed team aware of subsequently displaced across geophysical methods, including the different components that an the region, with numerous thrust potential field and active electrical exploration program needed and faults and remnant mud volcanoes. methods, and geochemical methods. the inter-relationships that deliver Currently, there is no model of The group defined a test area currently exploration success. seafloor manganese deposits that fits accessible under exploration licence, Peter Williams: [email protected] well with the Timor occurrences. where these techniques can be 3 Structural geology collaboration results in new find for Sumitomo East Deep Liese Zone JAMES SIDDORN James Siddorn, P.Geo., is a Practice Leader in Structural 4021 Geology, based in SRK’s Toronto office. He is a specialist in the structural In March 2010, Sumitomo Metal Gold mineralisation at Pogo is hosted analysis of ore Mining Pogo LLC (Sumitomo) within the structurally controlled Liese deposits, focused on commissioned SRK Consulting Canada vein system. Overall, the Liese vein deciphering the deposit-scale controls to undertake a structural geology system dips shallowly northwest and is a on ore plunge, geotechnical domains, interpretation of the Pogo district stacked system of three laminated veins and hydrogeological pathways. James in central Alaska, to assist ongoing (L1, L2, and L3). SRK and Sumitomo is an expert in the applied geological exploration targeting. The interpretation recognised that the lateral extent of interpretation of aeromagnetic data, was focused on compiling a structural the Liese vein system is large, with with extensive underground and geology interpretation of recently the L1 vein currently known to have a surface mapping experience, and broad acquired geophysical data, combined down-dip extent of greater than 1700 mining experience in conventional and with staged site visits, to examine the metres. The northeast margin of the mechanised underground mining. He structural geology of the Pogo deposit Liese vein system is truncated by a post- has spent 17 years in the structural and collaborate with the Sumitomo mineralisation diorite (about 95 million analysis and 3D geological modelling of exploration team. years old). The crosscutting nature of the gold, magmatic sulfide, silver, uranium,
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