Authors / CoAuthors
Huston, D.L. | Mernagh, T.P. | Hagemann, S. | Doublier, M.P. | Champion, D.C. | Jaques, A.L. | Czarnota, K. | Cayley, R. | Skirrow, R.G. | Bastrakov, E.N.
Abstract
Tectono-metallogenic systems are geological systems that link geodynamic and tectonic processes with ore-forming processes. Although fundamental geodynamic processes, which include buoyancy-related processes, crustal/lithospheric thinning and crustal/lithospheric thickening, have occurred throughout Earth's history, tectonic systems, which are driven by these processes, have evolved as Earth's interior has cooled. Although details remain controversial, tectonic systems are thought to have evolved from magma oceans in the Hadean through an unstable "stagnant-lid" regime in the earlier Archean into a proto-plate tectonic regime from the late Archean onwards. Modern-style plate tectonics is thought to have become dominant by the start of the Paleozoic. Although mineral systems with general similarities to modern or geologically recent systems have been present episodically through much of Earth's history, most of Earth's present endowment of mineral wealth was formed during and after the NeoArchean, when proto- or modern-style plate tectonic systems became increasinly dominant and following major changes in the chemistry of the atmosphere and hydrosphere. The characteristics of some mineral systems, such as the volcanic-hosted massive sulphide (VHMS) system, reflect these changes in tectonic style. Not only have tectono-metallogenic systems evolved in general over Earth's history, but specific tectono-metallogenic systems evolve over much shorter time frames. Most mineral deposits form in three general tectono-metallogenic systems: divergent systems, convergent systems, and intraplate systems. Although fundamental geodynamic processes have driven the evolution of these systems, their importance has changed as the systems evolved. For example, buoyancy-driven (mantle convection/plumes) and crustal thinning are the most important rocesses driving the early rift stage of divergent tectono-metallogenic systems, whereas buoyancy-driven processes (slab sinking) and crustal thickening are the most important processes during the subduction stage of convergent systems. Crustal thinning can also be an important process in the hinterland of subduction zones, producing back-arc basins than can host a number of mineral systems. As fundamental geodynamic processes act as drivers at some stage in virtually all tectonic systems, these cannot be used to identify tectonic systems. Moreover, as mineral systems are ultimately the products of these same geodynamic drivers, individual mineral deposits types cannot be used to determine tectonic systems, although mineral deposit assemblages can, in some cases, be indicative of the tectono-metallogenic system. Ore deposits are the products of geological (mineral) systems that operate over a long time frame (hundreds of millions of years) and at scales up to the craton-scale. In essence, mineral systems increase the concentrations of commodities through geochemical and geophysical processes from bulk Earth levels to levels amenable to economic mining. Mineral system components include the geological (tectonic and architectural) setting, the driver(s) of mineralising processes, metal and fluid sources, fluid pathways, depositional trap, and post-depositional modifications. All of these components link back to geodynamic processes and the tectonic system. For example, crustal architecture, which controls the spatial distribution of, and fluid flow, within mineral systems, is largely determined by geodynamic processes and tectonic systems, and the timing of mineralisation, which generally is relatively short (commonly < 1 Myr), correlates with local and/or far-field tectonic events.
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83744
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- External Publication
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- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Tectonics
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- Published_Internal
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2015-01-01T00:00:00
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