The trace element geochemistry of clinopyroxenes from pyroxenites in the Lewisian of NW Scotland: insights into light rare earth element mobility during granulite facies metamorphism

Rollinson, Hugh; Gravestock, Philip

doi:10.1007/s00410-011-0674-8

Cited by 17 publications

(29 citation statements)

References 31 publications

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“…Although not part of the conclusion of Bagas et al (2013), we would argue that the rocks with variable Th and U contents in southeast Greenland originate from protoliths similar to the Isua basalts, but underwent variable degrees of partial melting, during high-grade metamorphism, rather than originating from contrasting geodynamic settings within the same region. Similar mafi c pods are also found in the Mesoarchaean Lewisian granulite complex, northwest Scotland, which show evidence for signifi cant rare earth element mobility, as well as depletion of Th and U during a high-grade partial melting event (Weaver and Tarney, 1981;Rollinson and Gravestock, 2012). Given the regional evidence for partial melting around Innersuartuut, and the fact that Th and U are known to be mobilized in mafi c rocks at similar metamorphic conditions, we suggest that a more reasonable interpretation of the rocks on Innersuartuut would be that they represent reprocessed lower crustal equivalents of Isua-type IAT, and not OIB as claimed by Jenner et al…”

supporting

confidence: 54%

Eoarchean within-plate basalts from southwest Greenland: COMMENT

Szilas¹,

Hoffmann²,

Münker³

et al. 2014

Geology

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supporting

confidence: 54%

Eoarchean within-plate basalts from southwest Greenland: COMMENT

Szilas¹,

Hoffmann²,

Münker³

et al. 2014

Geology

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“…A suite of ultramafic-mafic complexes, including the Camas nam Buth occurrence at Scouriemore (a site of special scientific interest; SSSI), are most commonly exposed in the northern Central Region and occupy areas between 0.3 and 7.0 km 2 ( Fig. 1; Peach et al, 1907;O'Hara, 1961;Bowes et al, 1964;Davies, 1974;Sills et al, 1982;Rollinson and Gravestock, 2012;Johnson et al, 2012Johnson et al, , 2016.…”

Section: Regional Geology: the Lewisian Complexmentioning

confidence: 99%

Re-evaluating ambiguous age relationships in Archean cratons: Implications for the origin of ultramafic-mafic complexes in the Lewisian Gneiss Complex

Guice

McDonald

Hughes

et al. 2018

Precambrian Research

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Archean ultramafic-mafic complexes have been the focus of important and often contentious geological and geodynamic interpretations. However, their age relative to the other components of Archean cratons are often poorly-constrained, introducing significant ambiguity when interpreting their origin and geodynamic significance. The Lewisian Gneiss Complex (LGC) of the northwest Scottish mainland -a high-grade, tonalite-trondhjemite-granodiorite (TTG) terrane that forms part of the North Atlantic Craton (NAC) -contains a number of ultramafic-mafic complexes whose origin and geodynamic significance have remained enigmatic since they were first described. Previous studies have interpreted these complexes as representing a wide-range of geological environments, from oceanic crust, to the sagducted remnants of Archean greenstone belts. These interpretations, which are often critically dependent upon the ages of the complexes relative to the surrounding rocks, have disparate implications for Archean geodynamic regimes (in the NAC and globally). Most previous authors have inferred that the ultramafic-mafic complexes of the LGC pre-date the TTG magmas. This fundamental age relationship is re-evaluated in this investigation through re-mapping of the Geodh' nan Sgadan Complex (where tonalitic gneiss reportedly cross-cuts mafic rocks) and new mapping of the 7 km 2 Ben Strome Complex (the largest ultramafic-mafic complex in the LGC), alongside detailed petrography and spinel mineral chemistry. This new study reveals that, despite their close proximity in the LGC (12 km), the Ben Strome and Geodh' nan Sgadan Complexes are petrogenetically unrelated, indicating that the LGC (and thus NAC) records multiple temporally and/or petrogenetically distinct phases of ultramafic-mafic Archean magmatism that has been masked by subsequent high-grade metamorphism. Moreover, field observations and spinel mineral chemistry demonstrate that the Ben Strome Complex represents a layered intrusion that was emplaced into a TTG-dominated crust. Further to representing a significant re-evaluation of theLGC's magmatic evolution, these findings have important implications for the methodologies utilised in deciphering the origin of Archean ultramafic-mafic complexes globally, where material suitable for dating is often unavailable and field relationships are commonly ambiguous.

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“…569 Furthermore, the extent to which trace element data may be used to elucidate tectonic 570 environments in rocks that have undergone strong modification by magmatic andquestionable (Pearce, 2008(Pearce, , 2014aRollinson and Gravestock, 2012). Although many trace 573 elements may be considered immobile during high-temperature subsolidus metamorphism 574 and hydrothermal alteration, most have mineral/melt distribution coefficients that are far 575 from unity, leading to significant modification of trace element compositions as a result of 576 crystal settling and/or partial melting and melt loss (Fig.…”

Section: Trace Elements 442 443mentioning

confidence: 99%

“…1), Rollinson and Windley (1980) 674 suggested that the TTG gneisses intruded, and therefore post-dated, the layered ultramafic-675 mafic bodies (their figure 1), an interpretation followed by Rollinson and Gravestock (2012). 676…”

Section: Morb 618mentioning

confidence: 99%