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Titolo:
Geochemical evidence for the Trindade hotspot trace: Columbia seamount ankaramite
Autore:
Fodor, RV; Hanan, BB;
Indirizzi:
N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Raleigh, NC 27695 USA N Carolina State Univ Raleigh NC USA 27695 her Sci, Raleigh, NC 27695 USA San Diego State Univ, Dept Geol Sci, San Diego, CA 92182 USA San Diego State Univ San Diego CA USA 92182 Sci, San Diego, CA 92182 USA
Titolo Testata:
LITHOS
fascicolo: 4, volume: 51, anno: 2000,
pagine: 293 - 304
SICI:
0024-4937(200006)51:4<293:GEFTTH>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
SOUTH-ATLANTIC OCEAN; MANTLE PLUME; ISOTOPE EVIDENCE; SE BRAZIL; ROCKS; LEAD; MAGMATISM; EVOLUTION; AFRICAN; ISLANDS;
Keywords:
Trindade hotspot; Brazil magmatism; Columbia seamount; ankaramite; Pb isotopes;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
29
Recensione:
Indirizzi per estratti:
Indirizzo: Fodor, RV N Carolina State Univ, Dept Marine Earth & Atmospher Sci, POB 8208, Raleigh, NC 27695 USA N Carolina State Univ POB 8208 Raleigh NC USA 27695 NC 27695 USA
Citazione:
R.V. Fodor e B.B. Hanan, "Geochemical evidence for the Trindade hotspot trace: Columbia seamount ankaramite", LITHOS, 51(4), 2000, pp. 293-304

Abstract

The Columbia seamount similar to 825 km offshore from Brazil at similar to20 degrees S lies on the east-west 'trace' of the Trindade hotspot. Continental and oceanic magmatism believed to have originated with this hotspot is alkalic and SiO2-undersaturated, and dates from similar to 85 Ma in southern Brazil to < 3 Ma on the islands of Trindade and Martin Vat similar to 1100 km offshore. An ankaramite (clinopyroxene similar to 16 vol%) dredged from Columbia seamount(est. 10 Ma) conforms to this geochemistry with SiO2-undersaturated Al-rich clinopyroxene (8-13 wt.% Al2O3) and rhonite. Clinopyroxene isotopic compositions are Sr-87/Sr-86 = 0.703900, Nd-143/Nd-144 = 0.512786, (206)pb/Pb-204 = 19.190, Pb-207/Pb-204 = 15.045, and Pb-208/Pb-204 =39.242 - resembling those for Trindade, except for slightly higher Pb-207/Pb-204. The isotopic composition and abundance ratios among weathering-resistant Nh, La, and Yb suggest that Columbia seamount magmatism represents the present-day Trindade plume, but similar to 10 million years earlier and perhaps when the plume manifested a signature of 'contamination' from subducted sediments. The Columbia seamount analyses provide the first quantitative assessment for the Trindade hotspot trace existing between the Brazil margin and Trindade, strengthening the case for a continuum of magmatism extending from the similar to 85 Ma Brazilian igneous provinces of Poxoreu and Alto Paranaiba. (C) 2000 Elsevier Science B.V. All rights reserved.

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Documento generato il 04/04/20 alle ore 01:38:33