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Titolo:
Mantle sources and melting dynamics in the British palaeogene igneous province
Autore:
Kent, RW; Fitton, JG;
Indirizzi:
Univ Edinburgh, Grant Inst, Dept Geol & Geophys, Edinburgh EH9 3JW, Midlothian, Scotland Univ Edinburgh Edinburgh Midlothian Scotland EH9 3JW Midlothian, Scotland
Titolo Testata:
JOURNAL OF PETROLOGY
fascicolo: 7, volume: 41, anno: 2000,
pagine: 1023 - 1040
SICI:
0022-3530(200007)41:7<1023:MSAMDI>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
TERTIARY LAVA SUCCESSION; ISLE-OF-SKYE; ATLANTIC CONTINENTAL MARGINS; NW SCOTLAND; ICELAND PLUME; NORTH-ATLANTIC; FLOOD BASALTS; ISOTOPE GEOCHEMISTRY; WESTERN SCOTLAND; EARTH;
Keywords:
British Isles; magmatism; melting; North Atlantic; plume;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
74
Recensione:
Indirizzi per estratti:
Indirizzo: Kent, RW Coventry Univ, European & External Funding Off, Priory St, Coventry CV1 5FB, W Midlands, England Coventry Univ Priory St Coventry W MidlandsEngland CV1 5FB gland
Citazione:
R.W. Kent e J.G. Fitton, "Mantle sources and melting dynamics in the British palaeogene igneous province", J PETROLOGY, 41(7), 2000, pp. 1023-1040

Abstract

The North Atlantic igneous province offers an unrivalled opportunity to study mantle sources contributing to flood basalt magmatism, and melting dynamics associated with active and passive upwelling of hot mantle beneath thelithosphere. In this study, Palaeogene basalts sampled at localities across the British Isles (from the Hebrides in the north Lundy Island in the South) are shown to have concentrations of Nb, Zr and Y consistent with derivation from two mantle sources : 'Icelandic' (plume) mantle and hot N-MORB-like mantle forming an outer envelope to the plume. These sources were sampled over the period 61-58 Ma (chrons 26R-26N). Values of Delta Nb-an expression of the deficiency or excess of Nb relative to the lower bound of the data array for Icelandic basalt in Nb Zr-Y space-indicate that, with time, theproportion of 'Icelandic' material entering the melting regime below the British Isles (up to 1300 km from the plume axis) increased and then decreased relative to the contribution from the N-MORB source. Within the British Isles, subsidence data and basalt compositions suggest that melting to generate the parent magmas of the bulk of Palaeocene basalts occurred beneath intact lithosphere. Melting began at depths well in excess of 100km, made possible by the high temperature (similar to 1550 degrees C) of the ancestralIceland plume. In the final stages of magmatism, depleted melt fractions were generated beneath the Rockall Trough and other basins to the NW of the British Isles, at depths as shallow as 55km. These melt fractions were extracted rapidly from the mantle, without undergoing significant mixing with melt generated deeper in the melting column. The result is a distinctive magma type (Preshal More or Central Mull Tholeiite) not observed in the more southerly parts of the British Palaeogene igneous province.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 27/11/20 alle ore 09:54:45