Journal ArticleDOI
Polybaric differentiation of alkali basaltic magmas: evidence from green-core clinopyroxenes (Eifel, FRG)
TLDR
In this article, a model for polybaric magma evolution in the West Eifel is proposed, where primitive alkali basaltic lava rises through the upper mantle precipitating Al-augite en route It stagnates and differentiates near the crust/mantle boundary crystallizing Fe-rich fassaitic augites.Abstract:
The Quaternary foidites and basanites of the West Eifel (Germany) contain optically and chemically heterogeneous clinopyroxenes, some of which occur as discrete zones within individual crystals: Most clinopyroxene phenocrysts are made up of a core and a normally zoned comagmatic titanaugite mantle Most cores are greenish pleochroic and moderately resorbed (fassaitic augite) Some are pale green and strongly resorbed (acmitic augite) Cores of Al-augite composition and of Cr-diopside derived from peridotite xenoliths are rare The fassaitic augites are similar in trace element distribution pattern to the titanaugites, but are more enriched in incompatible elements The acmitic augites, in contrast, are clearly different in their trace element composition and are enriched in Na, Mn, Fe and depleted in Al, Ti, Sr, Zr A model for polybaric magma evolution in the West Eifel is proposed: Primitive alkali basaltic magma rises through the upper mantle precipitating Al-augite en route It stagnates and differentiates near the crust/mantle boundary crystallizing Fe-rich fassaitic augites The magma differentiated at high pressure is subsequently mixed with new pulses of primitive magma from which the rims of pyroxene are crystallized Sporadic alkali pyroxenite xenoliths are interpreted to represent cumulates of cognate phases formed within the crust and not metasomatized upper mantle material (Lloyd and Bailey 1975)read more
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Mineral Textures and Zoning as Evidence for Open System Processes
TL;DR: In this paper, the authors review the zoning and textures of minerals frequently encountered in volcanic rocks and the interpretations ascribed to these features in terms of open-system magmatic processes.
Journal ArticleDOI
Apatite in the mantle: implications for metasomatic processes and high heat production in Phanerozoic mantle
TL;DR: In this paper, it was shown that apatite has a widespread occurrence in Phanerozoic lithospheric mantle and can be divided into two geochemically distinct types using halogen content, presence or absence of structural CO 2, Sr and trace element ratios and abundances.
Journal ArticleDOI
The Geochemical Regimes of Piton de la Fournaise Volcano (Reunion) During the Last 530 000 Years
Francis Albarède,Béatrice Luais,G. Fitton,Michel P. Semet,Edouard Kaminski,B. G. J. Upton,Patrick Bachèlery,J.-L. Cheminee +7 more
TL;DR: In this paper, the authors report mineralogical results from the impingement on the base of the lithosphere of a solitary volcano with a radius of 100-130 km and a number of volcanic sequences spanning the 530 ka of the known velocity of 5-9 cm/yr.
Journal ArticleDOI
Evolution of Mauna Kea Volcano, Hawaii: Petrologic and geochemical constraints on postshield volcanism
TL;DR: In this paper, the authors show that the petrogenetic processes forming the post-shield lavas at Mauna Kea and other Hawaiian volcanoes reflect movement of the volcano away from the hotspot.
Journal ArticleDOI
Post-collisional transition from calc-alkaline to alkaline volcanism during the Neogene in Oranie (Algeria): magmatic expression of a slab breakoff
Christian Coulon,M'hamed Megartsi,Serge Fourcade,René C. Maury,Hervé Bellon,Amina Louni-Hacini,Joseph Cotten,Alain Coutelle,Daniel Hermitte +8 more
TL;DR: In this paper, a combined geochemical approach, using incompatible elements and Sr, Nd and O isotopes, allows us to conclude that the transitional basalts derived from the melting of a heterogeneous mantle source, at the boundary between lithosphere and asthenosphere.
References
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Journal ArticleDOI
Olivine-Liquid Equilibrium
Peter L. Roeder,R. F. Emslie +1 more
TL;DR: In this paper, a number of experiments have been conducted in order to study the equilibria between olivine and basaltic liquids and to try and understand the conditions under which OIVINE will crystallize.
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The mineralogy, geochemistry and origin of Iherzolite inclusions in Victorian basanites
Frederick A. Frey,David H. Green +1 more
TL;DR: The mineralogy of Iherzolite inclusions in Victorian basanites indicates an upper mantle origin, but a range of temperatures from igneous to metamorphic (subsolidus) is indicated by the mineral compositions as discussed by the authors.
Journal ArticleDOI
Trace element abundances in megacrysts and their host basalts: Constraints on partition coefficients and megacryst genesis
TL;DR: In this paper, rare earth and other trace element abundances are determined in megacrysts of clinopyroxene, orthopyroxenes, amphibole, mica, anorthoclase, apatite and zircon, as well as their host basalts, in an effort to gather data on mineral/melt trace element partitioning during high pressure petrogenesis of basic rocks.