Tectonic Setting, Characteristics, and Regional Exploration Criteria for Gold Mineralization in the Altaid Orogenic Collage: The Tien Shan Province as a Key Example
Alexander Yakubchuk, Andrew Cole, Reimar Seltmann, Vitaly Shatov, 2002. "Tectonic Setting, Characteristics, and Regional Exploration Criteria for Gold Mineralization in the Altaid Orogenic Collage: The Tien Shan Province as a Key Example", Integrated Methods for Discovery: Global Exploration in the Twenty-First Century, Richard J. Goldfarb, Richard L. Nielsen
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The richest gold province in central Eurasia, containing about two-thirds of the region's gold reserves, occurs in the late Paleozoic fold and thrust belts of the Tien Shan, a component of the giant Altaid orogenic collage. Extending through Uzbekistan, Tajikistan, Kyrgyzstan, and continuing into western China, the Tien Shan hosts an array of world-class gold deposits. Principally, these include late Paleozoic orogenictype gold deposits, such as Muruntau and Kumtor, two of the world's 10 biggest gold resources. Such deposits are often temporally and spatially associated with syntectonic granitoid intrusions that were emplaced into a terrane of metamorphosed terrigenous carbonaceous rocks of Late Proterozoic to middle Paleozoic age. In addition, many gold deposits are also related to world-class Cu porphyry, epithermal, and skarn systems formed earlier during early-middle Carboniferous magmatic-arc activity. Similar, but smaller and older, deposit types occur throughout the entire Altaids.
This orogenic collage consists of several Vendian to late Paleozoic magmatic arcs, which were first rifted off the eastern European and Siberian cratons. The clockwise rotation of Siberia relative to eastern Europe during middle and late Paleozoic caused several collisional episodes of these arcs, both with each other and with the cratons, as well as their gradual oroclinal bending. The formation of porphyry and epithermal deposits in the magmatic arcs coincides with the episodes of their oroclinal bending, whereas each collisional episode coincides with the formation of orogenic gold deposits. The giant gold deposits, however, formed during the final amalgamation of the collage in the Tien Shan province.
Although the Tien Shan has been actively studied during the Soviet era, it remains relatively underexplored, and the regionally extensive gold mineralization indicates that considerable potential for major new discoveries still exists in the province. It is a highly prospective terrane for orogenic gold deposits especially, but also for skarn, Carlin-like, and epithermal gold occurrences, which may represent a broad-scale telescoping of hydrothermal systems. Conceptual models of orogenic gold mineralization in the belt invoke interaction between imbricated thrusts, deep-seated high-angle reverse and strike-slip faults, synorogenic granitoid intrusions, and metalliferous black shales during late Paleozoic arc-continent collision and deformation. These factors represent the main geologic criteria that provide the maximum potential for the formation of gold deposits in the Tien Shan and can be extrapolated to assist exploration elsewhere in the Altaids.
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Integrated Methods for Discovery: Global Exploration in the Twenty-First Century
The dominant forces that affect the mining industry in today's economy are globalization, entrepreneurship, and unprecedented minerals availability. The current malaise and diminished economic importance of the base and precious metal mining industry in the world economy are the result of ongoing, longterm trends. Shifting market forces within a changed geopolitical landscape have resulted in excess supplies and reduced demands for high-unit-value mineral products and for geologists and engineers in the exploration and mining industries. Although these changes are still evolving, professionals and the mining companies that employ them must realize that these changes are irreversible.
Mining has five dominant characteristics: (1) it is essential to society, (2) it is effective in keeping society supplied with abundant, low-cost mineral products, (3) historically, it has been wealth destructive for investors, (4) it has been subsidized, and (5) it is shaped by social and political forces. What is different now is that instead of being subsidized, the industry is being handicapped by governments and abandoned by investors. The industry has reacted to a marketing problem with an inappropriate strategy of cost reduction and increased production. The increased supply has resulted in decreased prices. Mining companies are earning low or negative rates of return.
Remedies for the larger mining companies and the high-unit-value metals businesses include: Exemplary behavior to regain the trust of the public, governments and investors; Continued consolidation to become sector leaders; Profit through value-added vertical integration and direct marketing to consumers Development of innovative consumer-based financing mechanisms, especially for exploration ventures Individuals and small groups that have been displaced from the mainstream must become entrepreneurs. They must engineer their own survival by shifting careers or by finding, developing, and capitalizing on exploration and production opportunities that are unrecognized by, or are too small for, the major companies.
The mining industry is here to stay. It is too necessary to society to be abandoned; however, the future size and shape of the industry will probably be unrecognizable to most of us. It will be leaner and more opportunistic. It will be characterized by entrepreneurial corporations of all sizes that dominate niches and sectors and that anticipate and profit from the changing needs of society