Whole-rock geochemistry of amphibolites and metagabbros from the west Iberia Margin, Leg 173

The Leg 173 Site 1067 and 1068 amphibolites and metagabbros from the west Iberia margin exhibit variable whole-rock compositions from primitive to more evolved (Mg numbers = 49–71) that are generally incompatible trace and rare earth element enriched (light rare earth element [LREE] = 11–89 × chondrite). The Site 1067 amphibolites are compositionally similar to the basalts reported at Site 899 from this same region, based on trace and rare earth element contents. The Site 1068 amphibolites and metagabbros are similar to the Site 899 diabases but are more LREE enriched. However, the Sites 1067 and 1068 amphibolites and metagabbros are not compositionally similar to the Site 900 metagabbros, which are from the same structural high as the Leg 173 samples. The Leg 173 protoliths may be represented by basalts, diabases, and/or fine-grained gabbros that formed from incompatible trace element–enriched liquids.

[1]  J. Girardeau,et al.  Basalts, underplated gabbros and pyroxenites record the rifting process of the West Iberian margin , 1999 .

[2]  K. Seifert,et al.  Geochemistry of weathered mid-ocean ridge basalt and diabase clasts from Hole 899B , 1996 .

[3]  R. Whitmarsh,et al.  Models of the development of the West Iberia rifted continental margin at 40°30′N deduced from surface and deep‐tow magnetic anomalies , 1995 .

[4]  U. Schärer,et al.  Gabbro and related rock emplacement beneath rifting continental crust: UPb geochronological and geochemical constraints for the Galicia passive margin (Spain) , 1995 .

[5]  D. York,et al.  Additional 40Ar-39Ar dating of the basement and the alkaline volcanism of Gorringe Bank (Atlantic Ocean) , 1986 .

[6]  John F. Casey,et al.  Geochemical and geological evidence bearing on the origin of the Bay of Islands and Coastal Complex ophiolites of western Newfoundland , 1985 .

[7]  John F. Casey.  Comparison of major- and trace-element geochemistry of abyssal peridotites and mafic plutonic rocks with basalts from the MARK region of the Mid-Atlantic Ridge , 1997 .

[8]  D. Weis,et al.  Geochemistry of metamorphosed cumulate gabbros from Hole 900A, Iberia Abyssal Plain , 1996 .

[9]  M. Beslier,et al.  Petrology of the mafic rocks cored in the Iberia Abyssal Plain , 1996 .

[10]  C. Krawczyk,et al.  Evidence for Detachment Tectonics on the Iberia Abyssal Plain rifted margin , 1996 .

[11]  M. Beslier,et al.  28. 40 AR/ 39 AR DATING OF GABBROS FROM THE OCEAN/CONTINENT TRANSITION OF THE WESTERN IBERIA MARGIN: PRELIMINARY RESULTS 1 , 1996 .

[12]  Scott M. McLennan,et al.  Rare earth elements in sedimentary rocks; influence of provenance and sedimentary processes , 1989 .

[13]  N. Grevesse,et al.  Abundances of the elements: Meteoritic and solar , 1989 .

[14]  R. Grauch.  Rare earth elements in metamorphic rocks , 1989 .

[15]  G. Thompson,et al.  An evaluation of the behavior of the rare earth elements during the weathering of sea-floor basalt , 1979 .