The hunting of the snArc

Bédard, Jean H.; Harris, Lyal B.; Thurston, P. C.

doi:10.1016/j.precamres.2012.04.001

Cited by 221 publications

(100 citation statements)

References 324 publications

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“…The closest volcanic event is the eruption of the c. 2730 Ma andesitesrhyolites (Chen et al 2003) of the Marda Complex within the Marda block. Their Nd isotopic signatures (1Nd of c. 23; Table 2) suggest derivation from a crustal source, with geochemistry similar to a modern Andean-type margin (Chen et al 2003), although evidence of other subduction-related features is lacking, that is, high-grade metamorphic rocks, tectonic mélanges, ophiolites, and so on (Bédard et al 2012).…”

Section: Evaluation Of Sm-nd Data In Space and Timementioning

confidence: 99%

Crustal evolution, intra-cratonic architecture and the metallogeny of an Archaean craton

Mole

Fiorentini

Cassidy

et al. 2013

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The generation of the Earth's continental crust modified the composition of the mantle and provided a stable, buoyant reservoir capable of capturing mantle material and ultimately preserving ore deposits. Within the continental crust, lithospheric architecture and associated cratonic margins are a first-order control on camp-scale mineralization. Here we show that the evolving crustal architecture of the Archaean Yilgarn Craton, Western Australia, played a key role in controlling the localization of camp-scale gold, iron and nickel mineralized systems. The age and source characteristics of Archaean lithosphere are heterogeneous in both space and time and are recorded by the varying Nd isotopic signature of crustal rocks. Spatial and temporal variations in isotopic character document the evolution of an intra-cratonic architecture through time, and in doing so map transient lithospheric discontinuities where gold, nickel and iron mineral systems were concentrated. Komatiite-hosted nickel deposits cluster into camps localized within young, juvenile crust at the isotopic margin with older lithosphere; orogenic gold systems are typically localized along major structures within juvenile crust; and banded iron formation (BIF)-hosted iron deposits are localized at the edge of, and within, older lithospheric blocks. Furthermore, this work shows that crustal evolution plays an important role in the development and localization of favourable sources of nickel, gold and iron by controlling the occurrence of thick BIFs, ultramafic lavas and fertile (juvenile) crust, respectively. Fundamentally, this study demonstrates that the lithospheric architecture of a craton can be effectively imaged by isotopic techniques and used to identify regions prospective for camp-scale mineralization.

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Section: Evaluation Of Sm-nd Data In Space and Timementioning

confidence: 99%

Crustal evolution, intra-cratonic architecture and the metallogeny of an Archaean craton

Mole

Fiorentini

Cassidy

et al. 2013

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“…These mixing models are based, in part, on the bi-modal SiO 2 distribution of melt inclusions and rock textures that record disequilibrium conditions between crystals and melt (Reubi and Blundy, 2009). Hybridised melt models can reproduce many of the key geochemical features of some Archean andesitic rock suites (Bédard et al, 2013), however, binary mixing between basaltic and rhyolitic rocks are inconsistent with the curved, crystal fraction trends for the multiple time slices presented in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

“…Despite isotopic evidence that suggests the Archean depleted mantle source (at least by 3.8 Ga) was likely similar to today (Vervoort and Blichert-Toft, 1999), the mechanisms driving the production and composition of the continental crust in the geologic past are less understood (Bédard et al, 2013). Andesitic rocks are central to this debate because they represent the signature rock type at many young arcs and their occurrence in the Precambrian rock record is a key piece of evidence for tracing modern tectonic processes back into the geologic past.…”

Section: Introductionmentioning

confidence: 99%

Compositional symmetry between Earth’s crustal building blocks

Lawley¹

2016

Geochem. Persp. Let.

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doi: 10.7185/geochemlet.1612Arc magmatism drives the production of modern continental crust. However, the mode of crustal differentiation in the geologic past, particularly in the Archean, remains controversial. Herein I adopt a compositional approach to interrogate a global, igneous geochemical database (EarthChem Library) and document the evolving compositional history of basalt, andesite, and rhyolite, which represent the three main crustal building blocks. Basalt and andesite yield synced geochemical trends and progressively incompatible element-rich and compatible element-poor compositions that are consistent with extensive partial mantlemelting during the Archean. Post-Archean basaltic to andesitic rocks also tend to be more alkaline in character, which coupled with their high field-strength-and large-ion lithophile-element signature, points to the increased influence of Phanerozoic-style intra-plate magmatism on the global, rock record. Coeval rhyolitic rocks are depleted in these same elements, suggesting that post-Archean felsic magmas track the evolving compositions of their basaltic to andesitic source, which are, in turn, controlled by the partial melting trend. These complementary, or symmetric, geochemical trends between rock types shifted during the Proterozoic and heralded the onset of modern compositional relationships between crustal building blocks.

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“…The generation of Archaean granite-greenstone crust is more controversial, but there is growing consensus that both plate tectonics and mantle plumes played a role in the formation of this type of crust (e.g. Polat et al 1998;Percival 2007;Van Kranendonk et al 2007a, b, 2014Van Kranendonk 2010;Smith et al 2012;Bédard et al 2013). Higher mantle heat and more radiogenic-bearing granitic rocks created overall more mafic and less rigid crust, characterized by thick volcanic successions dominated by basaltic and komatiitic lavas, with subordinate felsic volcanic rocks and lesser volumes of sedimentary rocks compared with post-Archaean crust.…”

Section: Uniformitarianismmentioning

confidence: 99%

“…Granitic rocks in granite-greenstone terrains are dominated by TTG, but rather than having been derived exclusively from subducted oceanic crust as in modern subduction settings, a number of studies indicate a more varied origin for Archaean TTG, largely through infracrustal melting ( Fig. 6b -c Smithies et al 2009;Zeh et al 2011;Bédard et al 2013). Indeed, a number of Archaean granitegreenstone terrains are interpreted as volcanic plateaux, either truly oceanic or built on a substrate of older, at least in part sialic, crust ( Fig.…”

Section: Uniformitarianismmentioning

confidence: 99%

Continent formation through time

Kranendonk

Parman

Clift

2014

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Abstract:The continental crust is the primary archive of geological history, and is host to most of our natural resources. Thus, the following remain critical questions in Earth Science, and provide an underlying theme to all of the contributions within this volume: when, how and where did the continental crust form? How did it differentiate and evolve through time? How has it has been preserved in the geological record? This introductory review provides a background to these themes, and provides an outline of the contributions contained within this volume.

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The hunting of the snArc

Cited by 221 publications

References 324 publications

Crustal evolution, intra-cratonic architecture and the metallogeny of an Archaean craton

Crustal evolution, intra-cratonic architecture and the metallogeny of an Archaean craton

Compositional symmetry between Earth’s crustal building blocks

Continent formation through time

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