This database contains mineral major and trace element compositions of mantle peridodites recovered at the West Iberian margin during ODP Leg 149 and 173 (Whitmarsh et al., 1996, 1998). The West Iberian margin (WIM) represents the continental rifted margin marking the western edge of the Iberian Peninsula, being presently regarded as the most iconic example of a magma-poor passive margin. From north to south, the margin can be divided into three main segments (Fig. 1): (i) the Galicia margin; (ii) the South Iberia Abyssal Plain and (iii) the Tagus Abyssal Plain. This segmentation resulted from rifting and continental breakup between the North American and European/Iberian plates during Early Cretaceous time (Whitmarsh & Wallace, 2001 and references therein).
The samples of this dataset come from the Iberia Abyssal Plain (IAP) and more specifically from ODP Holes 899B, 1068A and 1070A and were analysed with EPMA and LA-ICP-MS analyses at the University of Milan (Italy) and Géosciences Montpellier (France).
The Patagonia is a vast region located in the southernmost tip of the South America continent. It shows a basaltic plateau formed by volcanic activity started in the Upper Cretaceous-Lower Cenozoic (e.g., Baker et al. 1981; Ramos et al. 1982) and continued during Plio-Quaternary period. Long this time, the basalts have changed their compositions due to a variation in the tectonic environments.
We studied mantle xenoliths hosted in the Plio-Quaternary alkaline basalts from Sierra Baguales, which are related to the back-arc environment (Munoz and Stern 1988, 1989; Munoz et al. 1989). Samples are recognized in two different areas (i) Cerro del Fraile and (ii) Cono Sin Nombre, which are situated to the NW and SE with respect to Sierra Baguales, respectively.
Mantle xenoliths are hosted in lavas localized in the Nemby area (25°24' S, 57°32' W; Asunciòn-Sapucai-Villarrica graben, ASV, central Paraguay: Fig.1), where a small melanephelinitite plug (Cerro Nemby), with elliptical topography (800 x 500 m, about 100 m above the plain), contains very abundant mantle xenoliths (10-15% by volume of the plug) together with crustal xenoliths (Comin-Chiaramonti et al., 2001).
According to Le Bas (1987), lavas consist of nephelinite and subordinately of ankaratrite (CIPW Ab < 5 wt% e Ne > 20 wt%).
The average size of the mantle xenoliths (10-12 cm, max 45 cm, i.e. the largest observed in ASV) and the compositional range (lherzolite to dunite to pyroxenite) make these xenoliths particularly suitable for a study regarding metasomatic processe(s) affecting the Sub-Continental Lithospheric Mantle of central Paraguay.
The dunite results to be the most abundant xenolith type in such lavas. In-situ geochemical characterization was performed on silicates and glasses from very fresh xenoliths, which document a large variety of rock types. Five samples were investigated, namely: i) dunite 3209; ii) spinel harzburgite 3284; iii) spinel lherzolite 3293; iv) olivine websterite 3253 and v) olivine clinopyroxenite 3270. The analyses were directly carried out on thin petrographic sections (30 µm thick) of the selected samples.