Matches in SemOpenAlex for { <https://semopenalex.org/work/W2063776800> ?p ?o ?g. }
- W2063776800 endingPage "514" @default.
- W2063776800 startingPage "499" @default.
- W2063776800 abstract "Osmium-isotope ratios were determined by an ion microprobe on the individual platinum-group minerals (PGM) from placers, which are associated with ultramafic intrusions of late Precambrian to Tertiary age. Unlike Os-isotope ratios in large layered mafic intrusions, these187Os/186Os ratios are low, and within a narrow range from 0.99 to 1.12, which is attributed to the occurrences of the intrusions. There was no opportunity to incorporate old crustal Os because of the small sizes of the intrusions and the mode of emplacement into the upper crustal level. In addition, the interaction with the host volcanic rocks of similar age, if any, would not have seriously affected the187Os/86Os ratios of the peridotites. While different phases of PGM in one grain have similar187Os/186Os ratios, there is a significant variation in a given district. The variation is attributed to a long-term heterogeneity in Re/Os ratios of the oceanic upper mantle. The lowest value in each area is lower than the value expected from the evolution of bulk Earth composition. The lowering may be due to primordially low Re/Os ratios in the mantle or preferential removal of Re by partial melting to form the continental crust. The former model is rejected because most chondrites have higher Re/Os ratios than type C1 and the core-mantle separation would not have lowered Re/Os ratios. The low187Os/186Os ratios are, therefore attributed to the extraction of continental crust by preferential removal of Re from the mantle through partial melting. The model is consistent with the depleted nature of oceanic peridotites (positiveεNd, negativeεSr, and low Re/Os ratios). Calculations of187Os/186Os ratios of the mantle residue suggest that the observed data are in accordance with a model involving the extraction of ∼ 2% melt by fractional fusion from the mantle of C1 chondritic composition at ∼ 2.0 Ga. If the bulk Earth has higher Re/Os ratios, as proposed by Martin [1], then the observed data require much larger degrees of partial melting or older mean age of partial melting at ∼ 3.0 Ga. The variation in Re/Os ratios in each area is ascribed to the various degrees of mixing of the depleted mantle source and more fertile material. This may be due to local heterogeneity in the mantle, “marble-cake” like mantle [2] or replenishment of Re and Os from a more fertile source by sulphide ( + CO2) in the mantle. Generally higher187Os/186Os ratios found in this study compared with those from the southern African sub-continental lithosphere [3] may be attributed to the nature of the latter which is more isolated than the oceanic mantle from the rest of the mantle. The occurrence of S in the mantle may influence ReOs isotope variations and the behavior of S may decouple the ReOs system from other lithophile radiogenic isotope systems." @default.
- W2063776800 created "2016-06-24" @default.
- W2063776800 creator A5010832994 @default.
- W2063776800 creator A5021883212 @default.
- W2063776800 date "1991-12-01" @default.
- W2063776800 modified "2023-10-17" @default.
- W2063776800 title "Osmium-isotope ratios of platinum-group minerals associated with ultramafic intrusions: Os-isotopic evolution of the oceanic mantle" @default.
- W2063776800 cites W1679968358 @default.
- W2063776800 cites W1966351406 @default.
- W2063776800 cites W1985295959 @default.
- W2063776800 cites W1986990031 @default.
- W2063776800 cites W1987112298 @default.
- W2063776800 cites W1990306083 @default.
- W2063776800 cites W1997218517 @default.
- W2063776800 cites W2008908076 @default.
- W2063776800 cites W2009022670 @default.
- W2063776800 cites W2011176927 @default.
- W2063776800 cites W2012657903 @default.
- W2063776800 cites W2019351007 @default.
- W2063776800 cites W2025200116 @default.
- W2063776800 cites W2026645255 @default.
- W2063776800 cites W2027602831 @default.
- W2063776800 cites W2029933612 @default.
- W2063776800 cites W2030183619 @default.
- W2063776800 cites W2032840455 @default.
- W2063776800 cites W2040012552 @default.
- W2063776800 cites W2043706408 @default.
- W2063776800 cites W2045022926 @default.
- W2063776800 cites W2047399789 @default.
- W2063776800 cites W2047567126 @default.
- W2063776800 cites W2054486238 @default.
- W2063776800 cites W2056720091 @default.
- W2063776800 cites W2056736929 @default.
- W2063776800 cites W2062104243 @default.
- W2063776800 cites W2063305856 @default.
- W2063776800 cites W2075540335 @default.
- W2063776800 cites W2076109412 @default.
- W2063776800 cites W2077433914 @default.
- W2063776800 cites W2078584777 @default.
- W2063776800 cites W2078758765 @default.
- W2063776800 cites W2083828239 @default.
- W2063776800 cites W2095129659 @default.
- W2063776800 cites W2095374727 @default.
- W2063776800 cites W2097756509 @default.
- W2063776800 cites W2119438235 @default.
- W2063776800 cites W2128320651 @default.
- W2063776800 cites W2132997778 @default.
- W2063776800 cites W2138053432 @default.
- W2063776800 cites W2147161167 @default.
- W2063776800 cites W2169117356 @default.
- W2063776800 cites W2321606097 @default.
- W2063776800 doi "https://doi.org/10.1016/0012-821x(91)90096-z" @default.
- W2063776800 hasPublicationYear "1991" @default.
- W2063776800 type Work @default.
- W2063776800 sameAs 2063776800 @default.
- W2063776800 citedByCount "60" @default.
- W2063776800 countsByYear W20637768002012 @default.
- W2063776800 countsByYear W20637768002014 @default.
- W2063776800 countsByYear W20637768002015 @default.
- W2063776800 countsByYear W20637768002016 @default.
- W2063776800 countsByYear W20637768002020 @default.
- W2063776800 countsByYear W20637768002021 @default.
- W2063776800 countsByYear W20637768002022 @default.
- W2063776800 countsByYear W20637768002023 @default.
- W2063776800 crossrefType "journal-article" @default.
- W2063776800 hasAuthorship W2063776800A5010832994 @default.
- W2063776800 hasAuthorship W2063776800A5021883212 @default.
- W2063776800 hasConcept C116862484 @default.
- W2063776800 hasConcept C121332964 @default.
- W2063776800 hasConcept C127313418 @default.
- W2063776800 hasConcept C130635790 @default.
- W2063776800 hasConcept C141646446 @default.
- W2063776800 hasConcept C161790260 @default.
- W2063776800 hasConcept C164304813 @default.
- W2063776800 hasConcept C167284885 @default.
- W2063776800 hasConcept C173776410 @default.
- W2063776800 hasConcept C17409809 @default.
- W2063776800 hasConcept C185592680 @default.
- W2063776800 hasConcept C195081551 @default.
- W2063776800 hasConcept C2776698055 @default.
- W2063776800 hasConcept C2779417233 @default.
- W2063776800 hasConcept C2781251403 @default.
- W2063776800 hasConcept C518104683 @default.
- W2063776800 hasConcept C540285154 @default.
- W2063776800 hasConcept C55493867 @default.
- W2063776800 hasConcept C555196967 @default.
- W2063776800 hasConcept C62520636 @default.
- W2063776800 hasConcept C67236022 @default.
- W2063776800 hasConcept C79572550 @default.
- W2063776800 hasConcept C84372278 @default.
- W2063776800 hasConcept C87355193 @default.
- W2063776800 hasConceptScore W2063776800C116862484 @default.
- W2063776800 hasConceptScore W2063776800C121332964 @default.
- W2063776800 hasConceptScore W2063776800C127313418 @default.
- W2063776800 hasConceptScore W2063776800C130635790 @default.
- W2063776800 hasConceptScore W2063776800C141646446 @default.
- W2063776800 hasConceptScore W2063776800C161790260 @default.
- W2063776800 hasConceptScore W2063776800C164304813 @default.