http://www.cnr.it/ontology/cnr/individuo/prodotto/ID179123

Melt migration in the upper mantle along the Romanche Fracture Zone (Equatorial Atlantic) (Articolo in rivista)

Type

Prodotto della ricerca (Classe)
Articolo in rivista (Classe)

Label

Melt migration in the upper mantle along the Romanche Fracture Zone (Equatorial Atlantic) (Articolo in rivista) (literal)

Anno

2002-01-01T00:00:00+01:00 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi

10.1016/S0024-4937(02)00116-0 (literal)

Alternative label

Tartarotti P.; Susini S.; Nimis P.; Ottolini L. (2002)
Melt migration in the upper mantle along the Romanche Fracture Zone (Equatorial Atlantic)
in Lithos (Oslo. Print); Academic Press Elsevier, Amsterdam (Paesi Bassi)
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

Tartarotti P.; Susini S.; Nimis P.; Ottolini L. (literal)

Pagina inizio

125 (literal)

Pagina fine

149 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume

63 (literal)

Rivista

Lithos (Rivista)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo

3 (literal)

Note

ISI Web of Science (WOS) (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni

Tartarotti P. a); Susini S. b); Nimis P. c); Ottolini L. d); a) Dipartimento di Geologia, Paleontologia e Geofisica, Università di Padova, via Giotto 1, 35137Padova, Italy; b) Istituto di Geologia Marina-CNR, 40100 Bologna, Italy; c) Dipartimento di Mineralogia e Petrologia, Università di Padova, 35137 Padova, Italy; d) Centro di Studio per la Cristallochimica e la Cristallografia-CNR, 27100 Pavia, Italy; (literal)

Titolo

Melt migration in the upper mantle along the Romanche Fracture Zone (Equatorial Atlantic) (literal)

Abstract

Textural and petrological data of mantle peridotites sampled in the central and western parts of the Romanche FZ (Equatorial Atlantic) during the oceanographic expedition PRIMAR-96 (Russian R/V Gelendzhik) are presented. The studied rocks are mantle peridotites impregnated by basaltic melts. Magmatic products occur in mineral aggregates with various textural features. Some textures (interstitial patches, gabbroic pockets) suggest that melt percolated the upper mantle by diffusive porous flow, in the ductile part of the lithosphere. Other textures (veins/dikes) are typical of melt migration within focused channels, representing brittle failures in the shallowest levels of the lithosphere. Electron and ion microprobe analyses show that the primary mineralogy of the peridotites was modified during magma infiltration that occurred deeper in the lithosphere. Chemical changes primarily involve Ti and Cr enrichment in spinel and Ti, Sr, Zr, Y and REE enrichment in residual clinopyroxene. Such refertilization prevents a correct evaluation of the degree of melting of the peridotites. By contrast, minor or no chemical interactions occurred in peridotites impregnated along fractures. Melts in impregnated peridotites have chemical features consistent with variably fractionated melts of probably MORB-type. Thermobarometric estimation of the studied samples suggest that the Romanche peridotites were impregnated at ~ 9-12 km in depth, and later re-equilibrated under subsolidus conditions at T ~ 750-1000°C. The widespread occurrence of trapped melt in the Romanche FZ peridotites may indicate that the lithospheric mantle in this region of the Atlantic is cold enough to trap significant amounts of melt, thus preventing the generation of a thick and continuous oceanic crust. We infer that the studied samples could have been produced by various extent of melt impregnation of a mantle residue left after partial melting degrees ranging either between 5-13% or 18-20%. This inference and the occurrence of both fertile and depleted paridotites in a closed area of the western Romanche FZ are in accord with a model of a small scale (<100 km) mantle heterogeneity along the Romanche FZ, as inferred by Bonatti et al. (1992) and Seyler and Bonatti (1997). (literal)

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