Evolution of LILE-enriched small melt fractions in the lithospheric mantle: a case study from the East African Rift

Geochemical and Sr–Nd–Pb isotopic compositions of lithospheric mantle: Spinel lherzolites in alkaline basalts from the northwestern Ethiopian plateau

“…Electron-microprobe analyses were performed using a (Bedini et al 1997;Bedini and Bodinier 1999;Lorand et al 2003;Meshesha et al 2011 Table 2. The analyses for whole-rock major elements were performed on glass beads using X-ray fluorescence spectrometry (Shimadzu XRF-1800) at Department of Physics and Earth Sciences (University of the Ryukyus) (Table 1).…”

“…As shown in Figure 4b, the Mg# of the olivine grains versus their modal proportions are plotted along the oceanic trend of Boyd et al (1997) and Boyd (1989). For comparison, the Mg# of the fields of depleted Archean lherzolites and Harzburgites (Boyd, 1989;Boyd et al, 1997) and the peridotites from southern Ethiopia (Bedini et al, 1997;Meshesha et al, 2011) are also included. Table 3.…”

“…These tectono-magmatic processes consequently induced substantial variations in the thermal structure and chemical composition of the upper mantle beneath Ethiopia and the surrounding regions. The mantle xenoliths hosted in the alkaline basalts of southern Ethiopia (Mega-Megado and Dilo-Goraye: Morten et al, 1992;Bedini et al, 1997;Bedini and Bodinier, 1999;Conticelli et al, 1999;Lorand et al, 2003;Reisberg et al, 2004;Meshesha et al, 2011), the central Main Ethiopian Rift xenoliths and xenocrysts (Debre Zeyte and Butajira: Rooney et al, 2005) and northwestern Ethiopia xenoliths (Injibara, Dedesa and Simien shield volcano: Roger et al, 1997Roger et al, , 1999Conticelli et al, 1999;Ayalew et al, 2003Ayalew et al, , 2009Ferrando et al, 2008;Beccaluva et al, 2009Beccaluva et al, , 2011Frezzotti et al, 2010) have therefore been the focus of extensive study over the previous two decades (Fig. 1a).…”

“…These mantle xenoliths are primarly of peridotite in composition. They display variable geochemical compositions attributed to various degrees of partial melting, recrystallization and metasomatism owing to the thermo-mechanical erosion of subcontinental lithosphere above a mantle plume head (e.g., Roger et al, 1997;Bedini et al, 1997;Bedini and Bodinier, 1999;Lorand et al, 2003;Reisberg et al, 2004) or interaction between the lithosphere and fluid and/or magma released from a deeper mantle plume (Roger et al, 1997(Roger et al, , 1999Conticelli et al, 1999;Rooney et al, 2005;Shinjo and Matsumura, 2006;Ferrando et al, 2008;Beccaluva et al, 2009Beccaluva et al, , 2011Meshesha et al, 2011).…”

Mantle Sulfides and their Role in Re–Os and Pb Isotope Geochronology

“…These BMS are always derived from small fractions of alkali melts that have experienced extensive reaction with the host peridotite in the uppermost SCLM (Menzies and Hawkesworth 1987;Bedini et al 1997;Alard et al 2011). Such melts have the potential to be particularly effective metasomatic agents as they are enriched in C-O-H-S and remain liquid, and therefore mobile, to low temperatures ( Fig.…”