Geologia

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BUllETIN OF THE SOCIETY OF ECONOMIC GEOlOGISTS

voL. 107

August

no. 5

A Special Issue on Archean Magmatism, Volcanism, and Ore Deposits: Part 1. Komatiite-Associated Ni-Cu-(PGE) Sulfide and Greenstone-Hosted Au Deposits Preface(1,2)
Patrick Mercier-Langevin,1,† MicheL g. houLé,1 Benoît DuBé,1 thoMas Monecke,2 Mark D. hannington,3 haroLD L. giBson,4 anD Jean goutier5
1 Geological 2Department

Survey of Canada, 490 rue de la Couronne, Québec, Québec G1K 9A9, Canada

of Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, Colorado 80401 of Earth Sciences, University of Ottawa, 140 Louis Pasteur, Ottawa, Ontario K1N 6N5, Canada of Earth Sciences, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada

3Department 4 Department 5 Ministère

des Ressources naturelles et de la Faune, 70 avenue Québec, Rouyn-Noranda, Québec J9X 6R1, Canada

Introduction the archean, which represents more than a third of Earth’s history, contains some of the largest and richest ore deposits of the world. Numerous cratons of variable size and age have been mapped (Fig. 1) and others are still being discovered or delineatedlargely due to the widespread use of high-precision U-Pb geochronology. One of the specific characteristics of Archean cratons is the coexistence and juxtaposition of different and major styles of base and precious metals deposits formed at different times and crustal levels (Poulsen et al., 2000; Groves et al., 2005a; Robert et al., 2005). It has long been recognized that Archean cratons areextremely well endowed in metals (e.g., Meyer, 1981; de Wit and Thiart, 2005), especially in komatiite-associated Ni-Cu(PGE), greenstone-hosted Au and volcanogenic massive sulfide (VMS) deposits. Most of these deposits were formed in periods of supercontinent(s) or supercraton(s) formation (e.g., ~2800−2500 Ma Kenorland: Williams et al., 1991; Aspler and Chiarenzelli, 1998; ~2600−2200 Ma Sclavia:Bleeker, 2003). Although some of these deposit types (greenstone-hosted Au and VMS) were formed episodically at various epochs in Earth’s history (cf. Goldfarb et al., 2010), Archean examples appear to be more common, and in many cases larger and/or richer. Although common in the Archean, the deposits are not uniformly distributed among the cratons, highlighting the fact that the metal endowment ofspecific assemblages reflects both secular variations and craton- to district-scale controls. For example, the Yilgarn craton is very well endowed in
author : e-mail, pmercier@nrcan.gc.ca Survey of Canada Contribution 20120033 (2) Ministère des Ressources naturelles et de la Faune Contribution 8439-2012-2013-02
(1) Geological † Corresponding

komatiite-associated Ni deposits, in contrast to theSuperior craton, which contains more significant VMS deposits. However, the study of Archean deposits and their environment is challenged by superimposed tectonic and metamorphic modifications. Thus, it is necessary to combine various techniques to understand the evolution and primary architecture of the host successions and to generate better exploration vectors in those challenging Archeanenvironments. Major differences between Archean and younger metallogenic processes or secular changes have been discussed in detail elsewhere (e.g., Kerrich et al., 2000, 2005; Groves et al., 2005a, b; Goldfarb et al., 2010; Huston et al., 2010; Naldrett, 2010). However, diverse styles of mineralization are being recognized among recently discovered deposits and prospects that are currently beingexplored in different parts of the world. Documenting the intrinsic characteristics of these deposits and better defining their genesis and evolution will help advance our understanding of metallogenic processes in the Archean. The objective of this part of the special issue on Archean magmatism, volcanism, and ore deposits is to highlight some of the metallogenic and associated processes that were...
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