Tertiary--Quaternary Extension-Related Alkaline Magmatism in Western and Central Europe

Wilson, Marjorie; Downes, Hilary

doi:10.1093/petrology/32.4.811

Cited by 391 publications

(173 citation statements)

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“…The isotope signatures of Cenozoic volcanics in Europe suggest the presence of subducted material in the European subcontinental mantle (Worner et al, 1986;Wilson and Downes, 1991), and the peridotite xenoliths from these regions had gone through a variety of metasomatic events (e.g. Stoch and Seck, 1980;Witt-Eickschen et al, 1993;Witt-Eickschen et al, 2003).…”

Section: Eifel: Du24 Du 25 Du26 Mm2 and Mm13mentioning

confidence: 99%

Nitrogen in peridotite xenoliths: Lithophile behavior and magmatic isotope fractionation

Yokochi

Marty

Chazot

et al. 2009

Geochimica et Cosmochimica Acta

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International audienceIn order to document the origin and speciation of nitrogen in mantle-derived rocks and minerals, the N and Ar contents and isotopic compositions were investigated for hydrous and anhydrous peridotite xenoliths from Ataq, Yemen, from Eifel, Germany, and from Massif Central, France. Nitrogen and Ar were extracted by stepwise combustion with a fine temperature resolution, followed by fusion in a platinum crucible. A large isotopic disequilibrium of up to 25.4‰ is observed within single peridotite xenoliths, with δ15N values as low as −17.3‰ in phlogopite whereas clinopyroxene and olivine show positive δ15N values. Identical Sr isotopic ratios of phlogopite, clinopyroxene and whole rock in this wehrlite sample are consistent with crystallization from a common reservoir, suggesting that the light N signature of phlogopite might be the result of isotopic fractionation during N uptake from the host magma. The nitrogen concentration is systematically high in phlogopite, (7.6–25.7 ppm), whereas that of bulk peridotite xenoliths is between 0.1 and 0.8 ppm. The high N content of phlogopite is at least partly due to host magma–mineral interaction, and may also suggest the occurrence of N as View the MathML source that substituted for K+ during mineral growth in mafic magmas. Such speciation is consistent with the fact that N and Rb contents correlate well for a set of samples from mantle regions that were affected by subduction-related metasomatism and magmatism. The N/Rb ratios of these samples are comparable with values estimated for subduction zone magmas, but are one order of magnitude lower than the N/Rb ratios characterizing subducting slabs. This difference suggests preferential release of N relative to alkalis in the forearc region. N/40Ar* ratios of minerals from analyzed mantle xenoliths are much higher than those of vesicles in MORBs and OIBs, requiring either the occurrence of nitrogen speciation in the mantle more compatible than Ar, significant loss of fluid phase during entrainment, or long residence time of volatile elements in the mantle source(s) of fluids to increase drastically the 40Ar* budget of the latter

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Section: Eifel: Du24 Du 25 Du26 Mm2 and Mm13mentioning

confidence: 99%

Nitrogen in peridotite xenoliths: Lithophile behavior and magmatic isotope fractionation

Yokochi

Marty

Chazot

et al. 2009

Geochimica et Cosmochimica Acta

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“…Wilson and Downes 1991). Volcanic activity has brought to the surface mantle xenoliths in some places.…”

Section: Introductionmentioning

confidence: 99%

Lithosphere thermal structure at the eastern margin of the Bohemian Massif: a case petrological and geophysical study of the Niedźwiedź amphibolite massif (SW Poland)

Puziewicz

Czechowski

Krysiński

et al. 2011

Int J Earth Sci (Geol Rundsch)

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The crustal section beneath amphibolite Niedźwiedź Massif (Fore-Sudetic Block in NE Bohemian Massif), modelled on the basis of geological and seismic data, is dominated by gneisses with subordinate granites (upper and middle crust) and melagabbros (lower crust). The geotherm was calculated based on the chemical analyses of the heat-producing elements in the rocks forming the crust and the measurements of their density and heat conductivity. The results were verified by heat flow calculations based on temperature measurements from 1,600 m deep well in the Niedźwiedź Massif and by temperaturedepth estimates in mantle xenoliths coming from the nearby ca. 4.5 My basanite plug in Lutynia. The paleoclimate-corrected heat flow in the Niedźwiedź Massif is 69.5 mW m -2 , and the mantle heat flow is 28 mW m -2 . The mantle beneath the Massif was located marginally relative to the areas of intense Cenozoic thermal rejuvenation connected with alkaline volcanism. This results in geotherm which is representative for lithosphere parts located at the margins of zones of continental alkaline volcanism and at its waning stages. The lithosphereasthenosphere boundary (LAB) beneath Niedźwiedź is located between 90 and 100 km depth and supposedly the rheological change at LAB is not related to the appearance of melt.

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“…Generation of alkalic magmas is usually considered to be a response to extension, which allows the asthenospheric mantle to rise up (as thermally anomalous mantle diapirs) and melt (Wilson & Downes, 1991). However, in the CPR, the alkalic magmatism generally followed post-collisional calc-alkaline magmatism that was related to earlier subduction.…”

Section: Introductionmentioning

confidence: 99%

Post-collisional Tertiary–Quaternary mafic alkalic magmatism in the Carpathian–Pannonian region: a review

Seghedi¹,

et al. 2004

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Mafic alkalic volcanism was widespread in the Carpathian Pannonian region (CPR) between 11 and 0.2 Ma. It followed the Miocene continental collision of the Alcapa and Tisia blocks with the European plate, as subduction-related calc-alkaline magmatism was waning. Several groups of mafic alkalic rocks from different regions within the CPR have been distinguished on the basis of ages and/or trace-element compositions. Their trace element and Sr-Nd-Pb isotope systematics are consistent with derivation from complex mantle source regions, which included both depleted asthenosphere and metasomatized lithosphere. The mixing of DMM-HIMU-EMII mantle components within asthenosphere-derived magmas indicates variable contamination of the shallow asthenosphere and/or thermal boundary layer of the lithosphere by a HIMU-like component prior to and following the introduction of subduction components.Various mantle sources have been identified: Lower lithospheric mantle modified by several ancient asthenospheric enrichments (source A); Young asthenospheric plumes with OIB-like trace element signatures that are either isotopically enriched (source B) or variably depleted (source C); Old upper asthenosphere heterogeneously contaminated by DM-HIMU-EMII-EMI components and slightly influenced by Miocene subduction-related enrichment (source D); Old upper asthenosphere heterogeneously contaminated by DM-HIMU-EMII components and significantly influenced by Miocene subduction-related enrichment (source E). Melt generation was initiated either by: (i) finger-like young asthenospheric plumes rising to and heating up the base of the lithosphere (below the Alcapa block), or (ii) decompressional melting of old asthenosphere upwelling to replace any lower lithosphere or heating and melting former subducted slabs (the Tisia block).

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Tertiary--Quaternary Extension-Related Alkaline Magmatism in Western and Central Europe

Cited by 391 publications

References 0 publications

Nitrogen in peridotite xenoliths: Lithophile behavior and magmatic isotope fractionation

Nitrogen in peridotite xenoliths: Lithophile behavior and magmatic isotope fractionation

Lithosphere thermal structure at the eastern margin of the Bohemian Massif: a case petrological and geophysical study of the Niedźwiedź amphibolite massif (SW Poland)

Post-collisional Tertiary–Quaternary mafic alkalic magmatism in the Carpathian–Pannonian region: a review

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