Criteres volcanologiques, petrologiques et geochimiques de la genese et de la differenciation des magmas basaltiques; exemple de l'Afar

Treuil, M.; Varet, Jacques

doi:10.2113/gssgfbull.s7-xv.5-6.506

Cited by 125 publications

(55 citation statements)

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“…The existence of a hot spot has been postulated from tectonic and geophysical evidences since 1971 (Morgan, 1971). Geochemical studies of volcanics have shown geographical variation (Schilling, 1973, Treuil andVaret, 1973;Barberi et al, 1980;Betton and Civetta, 1984;Barrat et al, 1990;Schilling et al, 1992) and temporal variation (Vidal et al, 1991;Deniel et al, 1993) in agreement with the hot spot model. Recent trace and radiogenic isotope studies allowed precise discussions on the sources of volcanism in Afar and showed the importance of mixing between several geochemical reservoirs such as the continental crust in the early stages of rifting, an ancient lithospheric subcontinental component (Vidal et al, 1991), a DMM component (Barrat el al., 1990) and a HIMU component (Vidal et al, 1991;Deniel et al, 1993); the proportions of each component are a matter of debate.…”

Section: Introductionmentioning

confidence: 76%

“…1). The main eruptive sequences were: the Ali Sabieh basalts which are local equivalents of Ethiopian flood basalts, the Ali Adde rhyolitic series , the Mablas alkaline rhyolites and basalts (15-10 Ma), the Dalha series (9-4 Ma), the Stratoide series (4-1 Ma), the Tadjoura series (3-1 Ma), which corresponds to the beginn ing of the Tadjoura Gulf opening, and the Quaternary actives regions of the Moussa Ali (0.8-0.1 Ma), the Asal rift and Manda Inakir (Treuil and Varet, 1973).…”

Section: Geological Setting and Samplesmentioning

confidence: 99%

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He, Ar, Sr, Nd and Pb isotopes in volcanic rocks from Afar: Evidence for a primitive mantle component and constraints on magmatic sources.

et al. 1993

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He, Ar, Sr, Nd and Pb isotopic ratios have been determined for a set of submarine basaltic glasses from the Gulf of Tadjoura and subaerial lavas from Afar, Republic of Djibuti. Rare gases were recovered by vacuum crushing and analysed with a new analytical system. Helium isotopic ratios up to 15 Ra show the occurrence of a "high 3He" hot spot beneath Afar and indicate the occurrence of a plume originating from a gas-rich, presumably deep, region of the mantle. He-Ar isotope systematics in dicate a mixing between three geochemical end-members: the plume component, enriched in 3He, a radiogenic, possibly crustal, component, and the atmosphere. Low 40Ar/36Ar ratios are interpreted as the result of selective atmospheric contamination of Afar magmas, but the process of contamination is unclear. In a He-Sr-Nd-Pb space, Afar data are plotted in a field similar to basic lavas emitted in Iceland (Djibuti territory) and in the Reykjanes Ridge (Gulf of Tadjoura) and differ by their He isotopic ratios from lavas emitted in EM (e.g., Gough and Tristan da Cunha) and HIMU (e.g., Saint Helena and Tubuaii) hot spots analysed so far.

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Section: Introductionmentioning

confidence: 76%

Section: Geological Setting and Samplesmentioning

confidence: 99%

He, Ar, Sr, Nd and Pb isotopes in volcanic rocks from Afar: Evidence for a primitive mantle component and constraints on magmatic sources.

et al. 1993

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“…A good positive linear correlation that passes through zero between Zr and Ti or Y suggests that these elements are behaving as nearly ideal incompatible elements (Treuil and Varet, 1973). Basalt compositions that define such a trend can realistically only be related by fractional crystallization of low-pressure basalt liquidus phases with very small distribution coefficients for these elements, such as olivine and plagioclase or minor clinopyroxene.…”

Section: Inter-unit Geochemical Variationsmentioning

confidence: 99%

“…22). Subsequent fractional crystallization of olivine, plagioclase, or minor clinopyroxene would then produce the two linear trends extending away from the origin (Treuil and Varet, 1973;Tarney et al, 1979).…”

Section: Inter-unit Geochemical Variationsmentioning

confidence: 99%

The Geochemistry, Mineralogy, and Petrology of Basalts from the West Philippine and Parece Vela Basins and from the Palau-Kyushu and West Mariana Ridges, Deep Sea Drilling Project Leg 59

Mattey¹,

Marsh²,

Tarney³

1981

Initial Reports of the Deep Sea Drilling Project

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“…6) trends are shown for N-and E-type MORB (Perfit et al 1980). Series related by crystal fractionation approximate to straight-line trends through the origin of such biaxial plots of a highly incompatible versus a slightly incompatible trace element (Treuil & Varet 1973) and significant differences in bulk distribution Rare earth elements aluminosilicates (e.g., pumpellyite) both as replacement and vein-forming minerals.…”

Section: -----------------------1\----mentioning

confidence: 66%

Discrimination between ophiolitic metabasalts, north D'Urville Island, New Zealand

Sivell¹,

Rankin²

1982

New Zealand Journal of Geology and Geophysics

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Whole-rock minor and trace element abundances, relict clinopyroxene compositions and petrographic features discriminate between 2 metabasalt units within the Patuki Volcanic complex, north D'Urville Island, New Zealand. The majority of the Patuki metabasalts show P, Zr, Nb, and light rare earth element (LREE) depletion and exhibit tholeiitic differentiation characteristics. They show close similarities to many abyssal tholeiites produced at modern spreading ridges (Ntype ocean ridge basalts). Pristine relict clinopyroxene preserves Ti-poor endiopside and endiopsidic augite compositions somewhat enriched in Cr, and shows systematic iron enrichment. A smaller proportion of the metabasalts are enriched in Nb, LREE, and related hygromagmatophile elements, but retain phenocryst assemblages and some trace element abundances similar to ocean-floor basalts. They contain Ca-and AI-rich titaniferous salites. These metabasalts are atypical of ophiolitic metabasalts and of metabasalts formed at normal ridge segments and show closest similarity to largeion-lithophile element enriched, ocean-floor tholeiites (E-type mid-ocean ridge basalts).At north D'Urville Island, the N-type metabasalts form an upper unit composed of massive and more rarely pillowed flows, and the group of E-type metabasalts form a lower unit composed of pillow lava and rare tabular bodies of ophitic spilite, associated with volcanic breccia. Interbedded marine sediments include sandstone, argillite, mudstone and minor tuffs, and ophiolitic breccia. The trace element data indicate that the 2 suites of Patuki metabasalts at north D'Urville Island are derived from geochemically distinct mantle sources, similar to sources from which N-and E-type midocean ridge basalts originate. The data imply mantle heterogeneity beneath a poorly evolved Middle Permian seafloor.

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Criteres volcanologiques, petrologiques et geochimiques de la genese et de la differenciation des magmas basaltiques; exemple de l'Afar

Cited by 125 publications

References 0 publications

He, Ar, Sr, Nd and Pb isotopes in volcanic rocks from Afar: Evidence for a primitive mantle component and constraints on magmatic sources.

He, Ar, Sr, Nd and Pb isotopes in volcanic rocks from Afar: Evidence for a primitive mantle component and constraints on magmatic sources.

The Geochemistry, Mineralogy, and Petrology of Basalts from the West Philippine and Parece Vela Basins and from the Palau-Kyushu and West Mariana Ridges, Deep Sea Drilling Project Leg 59

Discrimination between ophiolitic metabasalts, north D'Urville Island, New Zealand

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