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Titolo:
Palaeogene continental to oceanic magmatism on the SE Greenland continental margin at 63 degrees N: a review of the results of ocean drilling programlegs 152 and 163
Autore:
Fitton, JG; Larsen, LM; Saunders, AD; Hardarson, BS; Kempton, PD;
Indirizzi:
Univ Edinburgh, Dept Geol & Geophys, Edinburgh EH9 3JW, Midlothian, Scotland Univ Edinburgh Edinburgh Midlothian Scotland EH9 3JW Midlothian, Scotland Geol Survey Denmark & Greenland, DK-2400 Copenhagen NV, Denmark Geol Survey Denmark & Greenland Copenhagen Denmark NV nhagen NV, Denmark Univ Leicester, Dept Geol, Leicester LE1 7RH, Leics, England Univ Leicester Leicester Leics England LE1 7RH er LE1 7RH, Leics, England Scottish Univ Environm Res Ctr, E Kilbride G75 0QF, Lanark, Scotland Scottish Univ Environm Res Ctr E Kilbride Lanark Scotland G75 0QF cotland NERC, Isotope Geosci Lab, Keyworth NG12 5GG, Notts, England NERC KeyworthNotts England NG12 5GG b, Keyworth NG12 5GG, Notts, England
Titolo Testata:
JOURNAL OF PETROLOGY
fascicolo: 7, volume: 41, anno: 2000,
pagine: 951 - 966
SICI:
0022-3530(200007)41:7<951:PCTOMO>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
NORTH-ATLANTIC; ICELAND PLUME; CRUSTAL CONTAMINATION; EAST GREENLAND; FLOOD BASALTS; GEOCHEMISTRY; GENERATION; RIDGE; DIFFERENTIATION; TEMPERATURE;
Keywords:
flood basalt; geochemistry; Greenland; Palaeogene; Sr-Nd-Pb isotopes;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
57
Recensione:
Indirizzi per estratti:
Indirizzo: Fitton, JG Univ Edinburgh, Dept Geol & Geophys, W Mains Rd, Edinburgh EH9 3JW, Midlothian, Scotland Univ Edinburgh W Mains Rd Edinburgh Midlothian Scotland EH9 3JW
Citazione:
J.G. Fitton et al., "Palaeogene continental to oceanic magmatism on the SE Greenland continental margin at 63 degrees N: a review of the results of ocean drilling programlegs 152 and 163", J PETROLOGY, 41(7), 2000, pp. 951-966

Abstract

Drilling along a 63 degrees N transect off SE Greenland during Ocean Drilling Program (ODP) Legs 152 and 163 recovered a succession of volcanic rocksrepresenting all stages in the break-up of the volcanic rifted margin. Therocks range from pre-break-up continental tholeiitic flood basalt, throughsyn-break-up picrite, to truly oceanic basalt forming the main part of theseaward-dipping reflector sequence (SDRS). All the lava flows recovered from the transect were erupted in a subaerial environment. Ar-40 Ar-39 datingshows that the earliest magmas were erupted at similar to 61 Ma and has confirmed that the main part of the SDRS was erupted during C24r (56 53 Ma) following continental break-up. Magma represented by the pre-break-up lava flows was stored in crustal reservoirs where it evolved by fractional crystallization and assimilation of continental crust. Trace element and radiogenic isotope data show that the contaminant changed, through time, from lower-crustal granulite to a mixture of granulite and amphibolite, suggesting storage of magma at progressively shallower levels in the crust. The degree of contamination declined rapidly as break-up proceeded, and the youngest rocks sampled in the transect are uncontaminated by continental basement. Variation of, for example, Sc/Zr and Sm/Lu through the succession suggests a shallowing of the top of the mantle melting zone, accompanied by an increasein the average degree of melting with time from similar to 4% to similar to 12%. These modest degrees of melting imply mantle temperatures only similar to 100 degrees C hotter than normal upper mantle. Upwelling mantle must therefore have been fed dynamically to the melt zone to generate the igneous crust of 18 km thickness deduced from seismic and gravity studies. N-MORB-like magmas dominated the earliest part of the succession although a few flows of 'Icelandic' basalt were erupted in the pre-break-up phase. In contrast, the post-break-up magmas had an Icelandic mantle source. This suggeststhat the developing head of the ancestral Iceland plume was compositionally zoned, with a core of Icelandic mantle surrounded by a thick outer zone of hot, depleted upper mantle.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 27/11/20 alle ore 03:38:38