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Titolo:
Plume-lithosphere interactions in the generation of the basalts of the Kenya Rift, East Africa
Autore:
Macdonald, R; Rogers, NW; Fitton, JG; Black, S; Smith, M;
Indirizzi:
Univ Lancaster, Div Environm Sci, IENS, Lancaster LA1 4YQ, England Univ Lancaster Lancaster England LA1 4YQ ENS, Lancaster LA1 4YQ, England Open Univ, Dept Earth Sci, Milton Keynes MK7 6AA, Bucks, England Open Univ Milton Keynes Bucks England MK7 6AA nes MK7 6AA, Bucks, England Univ Edinburgh, Dept Geol & Geophys, Edinburgh EH9 3JW, Midlothian, Scotland Univ Edinburgh Edinburgh Midlothian Scotland EH9 3JW Midlothian, Scotland Univ Reading, PRIS, Reading RG6 2AB, Berks, England Univ Reading Reading Berks England RG6 2AB eading RG6 2AB, Berks, England British Geol Survey, Edinburgh EH9 3LA, Midlothian, Scotland British Geol Survey Edinburgh Midlothian Scotland EH9 3LA thian, Scotland
Titolo Testata:
JOURNAL OF PETROLOGY
fascicolo: 5, volume: 42, anno: 2001,
pagine: 877 - 900
SICI:
0022-3530(200105)42:5<877:PIITGO>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
UPPER-MANTLE BENEATH; GREGORY-RIFT; NORTHERN KENYA; ISOTOPIC EVIDENCE; TECTONIC EVOLUTION; SILALI VOLCANO; TRACE-ELEMENT; HEAT-FLOW; CONSTRAINTS; GEOCHEMISTRY;
Keywords:
Kenya Rift Valley; mantle plumes; geochemistry; metasomatism;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
96
Recensione:
Indirizzi per estratti:
Indirizzo: Macdonald, R Univ Lancaster, Div Environm Sci, IENS, Lancaster LA1 4YQ, England Univ Lancaster Lancaster England LA1 4YQ r LA1 4YQ, England
Citazione:
R. Macdonald et al., "Plume-lithosphere interactions in the generation of the basalts of the Kenya Rift, East Africa", J PETROLOGY, 42(5), 2001, pp. 877-900

Abstract

Major and trace element and Sr-Nd-Pb isotopic data for mafic volcanic rocks are used to asses the number of mantle plumes contributing to the Tertiary-Holocene magmatism of the Kenya Rift Valley, current estimates of which vary from none to three. Rocks ranging in composition from nephelinite to hypersthene-normative basalt have bee sampled from three lithospheric zones: the Tanzanian craton, the craton margin reworked during the late Proterozoic, and the Mozambique mobile belt. The magmas are interpreted as the products of variable degrees of partial melting within the spinel-garnet peridotite transition zone. Trace element and isotopic compositions from all three zones are broadly similar to those of oceanic island basalts, but there is considerable compositional variation, which is related to a strong over print from the lithosphere on plume-derived melts, Sr and Nd isotopic ratios provide the only clear distinction between magmatic rocks from the three lithospheric domains. Within each setting, mafic magmatism has tended to become less silica undersaturated with time, and at any one locality magmatism has migrated towards the centre of the rift. Magmas may have formed as a results of the infiltration of plume-derived melts into the base of the lithosphere. The extent of interaction of inferred plume melts with the lithosphere has not varied systematically in time or space. The plume component appears to be similar to the source of oceanic island basalts.

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Documento generato il 27/11/20 alle ore 10:28:54