The fast evolution of a crustal hot zone at the end of a transpressional regime: The Saint-Tropez peninsula granites and related dykes (Maures Massif, SE France)

in Lithos (2013), 162-163

Differentiation of tholeiitic basalt to A-type granite in the Sept Iles layered intrusion, Canada

in Journal of Petrology (2011)

Anorthosite formation by plagioclase flotation in ferrobasalt and implications for the lunar crust

in Geochimica et Cosmochimica Acta (2011), 75

The Farsund intrusion (SW Norway): a marker of Late-Sveconorwegian (Grenvillian) tectonism emplaced along a newly defined major shear zone

in Journal of Structural Geology (2010), 32

Sveconorwegian (Grenvillian) Massif type anorthosites and related granitoids result from postcollisional remelting of a continental arc root

in EOS : Transactions, American Geophysical Union (2009), 90(52), 11-02

Massif-type anorthosites and related granitoids result from post-collisional remelting of a continental arc root: the Sveconorwegian case

Conference (2009)

Petrogenesis of the Kabanga-Musongati layered mafic-ultramafic intrusions in Burundi (Kibaran Belt): geochemical, Sr-Nd isotopic constraints and Cr-Ni behaviour

in Journal of African Earth Sciences (2004), 39

A succession of mafic-ultramafic layered intrusions forms an alignment in the boundary zone between the Kibaran belt and the Tanzania craton. The intrusions represent a continuous series of cumulate rocks ... [more ▼]

A succession of mafic-ultramafic layered intrusions forms an alignment in the boundary zone between the Kibaran belt and the Tanzania craton. The intrusions represent a continuous series of cumulate rocks. For instance, in the Mukanda-Buhoro and Musongati (MBM) contiguous bodies, the series starts with dunite and passes to lherzolite, pyroxenite, norite, gabbronorite and anorthosite on top. Cumulate textures are conspicuous in all rock types and cryptic layering characterises cumulus mineral compositions, thus evidencing fractional crystallization as a major differentiation mechanism. The increase of Cr in the ultramafic members of the series indicates that chromite was not a liquidus mineral in dunite and lherzolite rocks, thus unable to form chromitite layers. The high Ni-content of dunite seems to preclude the existence of conjugate Ni-rich sulphide deposits. The 87Sr/86Sr initial ratio is relatively constant and averages 0.7087, with some values up to 0.712 due to local assimilation. Fine-grained rocks from the MBM area are isotopically (Nd and Sr) similar to the MBM cumulates. Modelling their crystallization produces cumulus mineral compositions similar to those in the Musongati ultramafic rocks, which suggests a broadly picritic parental magma. On the other hand, fine-grained rocks from the Nyabikere area are not related to the Nyabikere cumulates. Nd and Sr isotope ratios show that the MBM magmatism is related to an enriched source, possibly an old subcontinental lithospheric mantle. The Nyabikere dykes, as well as the Waga dykes, come from a depleted mantle source, as do the A-type granitoids occurring in the same boundary zone. Several lines of evidence point to two types of parental magmas, a picritic magma, and a more evolved magma, broadly similar to the Bushveld Main Zone magma. [less ▲]

Derivation of the 1.0-0.9 Ga ferro-potassic A-type granitoids of southern Norway by extreme differentiation from basic magmas

in Precambrian Research (2003), 124(2-4), 107-148

Sr, Nd isotopes and geochemistry of the Bayuda Desert high-grade metamorphic basement (Sudan): An early Pan-African oceanic convergent margin, not the edge of the East Saharan ghost craton?

in Precambrian Research (2001), 109(1-2), 1-23

The high-grade metamorphic basement of the Bayuda Desert is situated at the inferred transition between the juvenile Neoproterozoic mainly greenschist facies Arabian-Nubian Shield (ANS) and the pre ... [more ▼]

The high-grade metamorphic basement of the Bayuda Desert is situated at the inferred transition between the juvenile Neoproterozoic mainly greenschist facies Arabian-Nubian Shield (ANS) and the pre-Neoproterozoic mainly amphibolite facies domain of the East Saharan Ghost Craton. New geochemical and Sr-Nd isotope data reveal that this basement in Bayuda constituted a Neoproterozoic oceanic convergent margin succession with limited and probably late input of old material. Within this series, garnet amphibolites and epidote-biotite gneisses have geochemical characteristics of HFSE-depleted tholeiitic basalts and low- to medium-K dacites and rhyodacites, indicating magmatism in an oceanic island arc or back-arc basin environment. This magmatism occurred at 806 ± 19 Ma (Sm-Nd 11 WR isochron), similar in age to arc magmatism in the ANS. Leucocratic gneisses, muscovite schists and garnet-biotite schists form the dominant meta-sedimentary rocks of the study area. They were primarily derived from two different sources: volcanogenic sediments from a Neoproterozoic island arc (TDM Nd model ages between 790 and 900 Ma) and terrigeneous sediments from an older continental source (TDM Nd model ages up to 2100 Ma). The volcanosedimentary succession was metamorphosed under amphibolite facies conditions prior to 670 Ma, probably at approximately 700 Ma. The high-grade metamorphism is related to a frontal collisional event that also produced syn-collisional peraluminous granites preserved as muscovite-biotite gneisses. Meta-igneous rocks from eastern Bayuda have εNd values at 806 Ma of + 5.2 ± 0.4, indicating a less depleted mantle source (crustal contamination can be excluded) than the neighbouring Gabgaba-Gebeit terrane (εNd, ca. + 7) from the Arabian-Nubian shield. Less depleted mantle source is also known at Jebel Moya to the south, and inside the Arabian-Nubian Shield to the southeast of Bayuda. Lithological and structural similarities (dominantly northeast striking foliation) with the Bayuda Desert succession occur in many parts of central and western Sudan, suggesting a comparable geodynamic evolution. It is proposed that a Neoproterozoic oceanic convergent margin (Bayuda type succession) collided at approximately 700 Ma to the northwest with the East Saharan ghost craton, whose easternmost limit must lie below or more to the west than previously thought. © 2000 Elsevier Science B.V. [less ▲]

Two distinct post-collisional magmatic suites in the Sveconorwegian of southern Norway : Consequences for the evolution of the Proterozoic continental lithosphere

in Journal of Conference Abstracts (2001), 6