Platinum-group elements and melt percolation processes in Sidamo spinel peridotite xenoliths, Ethiopia, East African Rift

Lorand, Jean‐Pierre; Reisberg, Laurie; Bedini, R. M.

doi:10.1016/s0009-2541(02)00407-2

Cited by 93 publications

(54 citation statements)

References 46 publications

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“…O c e a n ic tr e n d Beccaluva et al (2009) this study Roger et al (1997Roger et al ( , 1999 Beccaluva et al (2011) Figure 4. Selected mineral composition of spinel lherzolites from this study compared to previously published lherzolite data from northwestern Ethiopian plateau (Roger et al 1997(Roger et al , 1999Conticelli et al 1999;Ferrando et al 2008;Beccaluva et al 2009), field of southern Ethiopia (dashed line, Bedini et al 1997;Conticelli et al 1999;Lorand et al 2003;Meshesha et al 2011) and field of xenoliths hosted in Oligocene basalts (gray field, Roger et al 1997Roger et al , 1999 (Figs. 4c and 4d).…”

Section: Mineral Chemistrymentioning

confidence: 83%

“…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).…”

Section: Methodsmentioning

confidence: 99%

“…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).…”

Section: Introductionmentioning

confidence: 99%

“…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).…”

Section: Introductionmentioning

confidence: 99%

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

Meshesha¹,

Shinjo

Orihashi

2014

Journal of Mineralogical and Petrological Sciences

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The geochemical characteristics of mantle xenoliths (spinel lherzolites) in Quaternary alkaline basalts from the northwestern Ethiopian plateau provide new insight into the conditions of melting associated with the Afar plume. The major element compositions of the spinel lherzolites are in the range of those of the primitive mantle. The high modal content of the clinopyroxene (14-23%) indicate that the mantle xenoliths are fertile spinel lherzolites that have experienced insignificant partial melting. However, enrichment in highly incompatible elements (LREE, Ba, Pb, Th, and U) and the absence of any typical metasomatic minerals indicate that the spinel lherzolites underwent an event of later cryptic metasomatic enrichment induced by plume-related, hydrous fluid-rich silicate melts. The

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Section: Mineral Chemistrymentioning

confidence: 83%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Meshesha¹,

Shinjo

Orihashi

2014

Journal of Mineralogical and Petrological Sciences

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“…In off-craton xenoliths, sulfide precipitation has also been attributed to sulfidation reactions between S-rich fluids and olivine, or metals dissolved in highly alkaline, volatile-enriched melts. Sulfides related to sulfidation have been identified in xenolith suites from the Kerguelen archipelago , the Western United States (Lee 2002), and the Massif Central, France (Lorand et al 2003b) and Languedoc, France (Alard et al 2011).…”

Section: Peridotite-hosted Sulfidesmentioning

confidence: 99%

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

Harvey¹,

Warren²,

Shirey³

2016

Highly Siderophile and Strongly Chalcophile Elements in High-Temperature Geochemistry and Cosmochemistry

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Genesis and tectonic implications of cumulate pyroxenites and tectonite peridotites from the Nagaland–Manipur ophiolites, Northeast India: constraints from mineralogical and geochemical characteristics

et al. 2016

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The Nagaland–Manipur ophiolites (NMO) of Northeast India forms a part of the Tethyan ophiolites and comprises a suite of tectonite peridotites and cumulate mafic–ultramafic sequence with mafic extrusive–intrusive rocks, felsic intrusives and oceanic pelagic sediments along with minor podiform chromitites. However, sheeted dykes, which are considered as a significant component of ophiolites, are absent in the NMO. The tectonite peridotites are distinguished from the cumulate pyroxenites by the presence of pyroxene lineation, deformed bands and strained extinction in olivine, kink twin lamellae in pyroxene. Both the tectonite peridotites and cumulate pyroxenites contain aluminous spinel with Cr number [Cr# = Cr/(Cr + Al)] in the range of 0.14 to 0.29 and 0.27 to 0.48, respectively. Mg number [Mg# = Mg/(Mg + Fe2+)] in Cr‐spinel is higher in tectonite peridotites (0.71–0.76) than cumulate pyroxenites (0.44–0.53). Chondrite‐normalized rare earth elements (REE) patterns of cumulate pyroxenites exhibit depleted at light REEE (LREE) (LaN/SmN = 0.380–0.759) but flat middle REE (MREE) to heavy REE (HREE) (SmN/YbN = 0.622–0.756). However, the tectonite peridotites show gradual decrease in concentrations from HREE to MREE (SmN/YbN = 0.285–0.460) and slight increase in LREE (LaN/SmN = 0.721–2.201). The cumulate pyroxenites show strong enriched PPGE patterns and higher PGE concentrations (∑PGE = 85.8–163.5 ppb) compared with the tectonite peridotites (∑PGE = 34.8–113.0 ppb). The estimated equilibration temperature ranges from 890 to 931 °C for cumulate pyroxenites and 971 to 1156 °C for tectonite peridotites. The olivine–spinel equilibrium along with Cr‐spinel chemistry and PGE data suggests that the tectonite peridotites represent the residual mantle left after limited extraction of basaltic melts by low‐degree partial melting (<15%). Conversely, the presence of highly magnesian orthopyroxene and clinopyroxene in the cumulate pyroxenites in conjunction with their geothermometry suggests that they were formed at high pressure and temperature by magmatic fractionation from the basaltic melt. The geochemical data together with field and petrographical evidences indicate that both the tectonite peridotites and cumulate pyroxenites are essentially spinel‐bearing and devoid of plagioclase, suggesting their derivation in the mantle beyond the stability limit of plagioclase in a mid‐oceanic ridge tectonic setting. We conclude that the ultramafic sequence of the NMO was initially generated at a mid‐oceanic ridge tectonic setting close to the eastern boundary of the Indian passive margin and then thrust over the continental margin of the Indian Plate towards the west during its collisional and subduction process with/beneath the Myanmar Plate. Copyright © 2016 John Wiley & Sons, Ltd.

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Platinum-group elements and melt percolation processes in Sidamo spinel peridotite xenoliths, Ethiopia, East African Rift

Cited by 93 publications

References 46 publications

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

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

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

Genesis and tectonic implications of cumulate pyroxenites and tectonite peridotites from the Nagaland–Manipur ophiolites, Northeast India: constraints from mineralogical and geochemical characteristics

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