Nature of mantle source contributions and the role of contamination and in situ crystallisation in the petrogenesis of Proterozoic mafic dykes and flood basalts Labrador
Article Abstract:
The hydrous phases of phlogopite and hornblende in the sub-lithosphere mantle have a significant effect on the petrogenesis of Proterozoic mafic dykes and flood basalts. In an analysis of mafic dykes and flood basalts from the Harp Lake and Seal Lake areas of Labrador, some compositional variations may be due to both in situ crystallization and contamination of asthenospheric magmas by veined material from the upper asthenosphere and the lower lithosphere These processes account for the wide variation in trace element ratios. Continental crust does not appear to be a source of variation.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1995
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A possible role for garnet pyroxenite in the origin of the "garnet signature" in MORB
Article Abstract:
Partial melting of pyroxenite is probably responsible for the garnet signature in mid-ocean ridge basalts (MORB). Geochemical and phase equilibrium studies on the abundances and compositions of mantle pyroxenites from alpine massifs suggest the greater likelihood of a garnet pyroxenite parent than a peridotite one for the presence of garnet. A quantitative model of melting of a peridotite/pyroxenite mantle reveals the effect of the presence of pyroxenite on the geochemistry of MORB. Factors controling such effects have been discussed.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1996
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Geochemistry of mafic dikes in the Adirondack mountains: implications for late Proterozoic continental rifting
Article Abstract:
The Adirondack mafic dikes are characterized as magmatism formed from the Laurentian continental rift during the late Proterozoic era. The dikes are composed mostly of alkaline basalts containing high levels of Ti, P and REE. Furthermore, the Hudson Highlands in New York and the southern Appalachians have dikes that resemble the geochemistry of the Adirondack dikes. In addition, the La/Ta (Nb) ratios show that the source of present-day ocean island basalts and the Adirondack mantle are similar.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1992
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