Metallogeny of mantle-rooted structures extending across the western edge of the Proterozoic North American craton

Kutina, Jan

doi:10.1127/gtm/4/1991/21

Cited by 2 publications

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“…3), the shallow manifestation of an Archean-Proterozoic suture zone, at its confluence with other regional-scale structural elements (Billingsley and Locke, 1941;Ericksen, 1976;Presnell, 1997). Kutina (1991) considered the Uinta axis to be part of a mantle-penetrating structure that transgresses the entire Cordilleran margin.…”

Section: Porphyry Copper-gold Depositsmentioning

confidence: 99%

“…Therefore, a lower-crustal or subcontinental lithospheric mantle gold preconcentration may not offer an adequate explanation for the recurrence of gold mineralization events unless the accreted terranes were originally rifted from the craton near their sites of eventual accretion (Colpron et al, 2007) and/or overthrust the continental margin along shallow-level décollements (Snyder et al, 2002). Kutina's (1991) concept of ore deposit localization by mantle-rooted, latitudinal discontinuities cutting across both the craton and accreted terranes fails to adequately explain the gold belts, most of which are oriented parallel, not transverse, to the Cordilleran margin. Alternative explanations might include preexisting metal concentrations in the mantle wedge (e.g., McInnes et al, 1999;Fig.…”

Section: Metallogenic Considerationsmentioning

confidence: 99%

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Special Paper: Major Gold Deposits and Belts of the North and South American Cordillera: Distribution, Tectonomagmatic Settings, and Metallogenic Considerations

Sillitoe¹

2008

Economic Geology

139

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A compilation of economically viable gold concentrations containing ≥10 Moz in the North and South American Cordillera reveals the existence of 22 discrete belts in addition to five major isolated deposits, most formed over the last 150 m.y. The gold concentrations are attributed to eight widely recognized deposit types, of which porphyry, sediment-hosted, and high-sulfidation epithermal are economically the most important. Individual gold belts are typically several tens to hundreds of kilometers long, dominated by single deposit types, and metallogenically active for relatively brief periods (<5-20 m.y.).Many of the gold belts and major isolated deposits were generated under extensional or transtensional tectonic conditions in either arc or back-arc settings. Nevertheless, the two main high-sulfidation epithermal gold belts were generated in thickening or already-thickened crust during low-angle subduction. Eight other gold belts or districts also accompanied compression or transpression, with two of them, the main orogenic gold belts, occupying fore-arc sites. There is a strong suggestion that the preeminent Cordilleran gold concentrations formed either during or immediately following prolonged contraction. The major gold deposits and belts occur along the craton edge as well as in adjoining accreted terranes, but almost all are of postaccretionary timing. Many of the gold belts and isolated deposits were localized by crustal-scale faults or lineaments, which may be either parallel or transverse to the Cordilleran margin.The gold concentrations accumulated during active subduction, commonly in close spatial and temporal association with intermediate to felsic, medium-to high-K calc-alkaline igneous rocks. By contrast, the lowsulfidation epithermal gold deposits accompany bimodal volcanic pulses of calc-alkaline, tholeiitic, or alkaline affinity. However, a gold-alkaline rock association is uncommon. A genetic link between gold mineralization and coeval magmatism is widely accepted for most of the deposit types, the exceptions being the sedimenthosted and orogenic gold deposits.Notwithstanding the small cumulative extent of the gold concentrations relative to the entire Cordilleran margin, there is a marked tendency for two or more belts or isolated deposits of different ages and genetic types to occur in close proximity within relatively restricted arc (including fore-and back-arc) segments. In the case of the western United States, for example, six belts and four isolated major deposits make up a particularly prominent cluster. If fortuity is discounted, this clustering or pairing of gold concentrations must imply a predisposition of certain arc segments to gold mineralization. An analogous situation is evident for other metals, particularly copper and tin. The reason for the recurrent generation of major deposits and belts dominated by one or more metals remains uncertain, although heterogeneously distributed metal preconcentrations, favorable redox conditions, or other parameters somewhere above the subduct...

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Section: Porphyry Copper-gold Depositsmentioning

confidence: 99%