Matches in SemOpenAlex for { <https://semopenalex.org/work/W2087680319> ?p ?o ?g. }
- W2087680319 endingPage "154" @default.
- W2087680319 startingPage "134" @default.
- W2087680319 abstract "Madagascar is one of the most important gem-producing countries in the world, including ruby and sapphires. Gem corundum deposits formed at different stages in the geological evolution of the island and in contrasting environments. Four main settings are identified: (1) Gem corundum formed in the Precambrian basement within the Neoproterozoic terranes of southern Madagascar, and in the volcano-sedimentary series of Beforona, north of Antananarivo. In the south, high-temperature (700 to 800 °C) and low-pressure (4 to 5 kbar) granulites contain deposits formed during the Pan-African orogenesis between 565 and 490 Ma. They accompany mafic and ultramafic complexes (ruby deposits of the Vohibory group), skarns at the contact between Anosyan granites and the Proterozoic Tranomaro group (sapphire deposits of the Tranomaro–Andranondambo district), and shear-zone corridors cross-cutting feldspathic gneisses, cordieritites and clinopyroxenites in the Tranomaro, Vohimena and Androyan metamorphic series (biotite schist deposits of Sahambano and Zazafotsy, cordieritites of Iankaroka and Ambatomena). The circulation of fluids, especially along discontinuities, allowed in-situ alkaline metasomatism, forming corundum host rocks related to desilicified granites, biotitites, “sakenites” and “corundumites”. (2) Gem corundum also occurs in the Triassic detrital formations of the Isalo group, as giant palaeoplacers in the Ilakaka–Sakaraha area. Here, sapphires and rubies may come from the metamorphic granulitic terranes of southern Madagascar. (3) Gem corundum deposits occur within the Neogene-Quaternary alkali basalts from Ankaratra (Antsirabe–Antanifotsy area) and in the Ambohitra Province (Nosy Be, Ambato and Ambondromifehy districts). Primary deposits are rare, except at Soamiakatra where ruby in gabbroic and clinopyroxenite xenoliths within alkali-basalts probably derive from mantle garnet peridotites. The blue-green-yellow sapphires typical of basaltic fields are always recovered in palaeoplacer (in karst formed upon Jurassic limestones from the Montagne d'Ambre, Antsiranana Province) and alluvial and soil placers (Ankaratra volcanic massif). (4) Deposits occur within Quaternary eluvial, colluvial and alluvial concentrations, such as high-quality rubies from the Andilamena and Vatomandry deposits." @default.
- W2087680319 created "2016-06-24" @default.
- W2087680319 creator A5000735302 @default.
- W2087680319 creator A5009254056 @default.
- W2087680319 creator A5022699229 @default.
- W2087680319 creator A5032383381 @default.
- W2087680319 creator A5036525960 @default.
- W2087680319 creator A5040727181 @default.
- W2087680319 creator A5046735064 @default.
- W2087680319 creator A5051917023 @default.
- W2087680319 creator A5064128211 @default.
- W2087680319 creator A5077713973 @default.
- W2087680319 creator A5077866276 @default.
- W2087680319 creator A5078535087 @default.
- W2087680319 creator A5078563658 @default.
- W2087680319 creator A5087643758 @default.
- W2087680319 date "2008-09-01" @default.
- W2087680319 modified "2023-09-27" @default.
- W2087680319 title "Gem corundum deposits of Madagascar: A review" @default.
- W2087680319 cites W1602577073 @default.
- W2087680319 cites W1983567888 @default.
- W2087680319 cites W1984458536 @default.
- W2087680319 cites W1987251581 @default.
- W2087680319 cites W1994888004 @default.
- W2087680319 cites W1998395901 @default.
- W2087680319 cites W2000950886 @default.
- W2087680319 cites W2002668690 @default.
- W2087680319 cites W2004050115 @default.
- W2087680319 cites W2016904546 @default.
- W2087680319 cites W2017299709 @default.
- W2087680319 cites W2022178895 @default.
- W2087680319 cites W2029570599 @default.
- W2087680319 cites W2060282393 @default.
- W2087680319 cites W2069267578 @default.
- W2087680319 cites W2070899407 @default.
- W2087680319 cites W2078236626 @default.
- W2087680319 cites W2085684842 @default.
- W2087680319 cites W2088464507 @default.
- W2087680319 cites W2094309826 @default.
- W2087680319 cites W2104453960 @default.
- W2087680319 cites W2105743944 @default.
- W2087680319 cites W2107742656 @default.
- W2087680319 cites W2142800396 @default.
- W2087680319 cites W2321457144 @default.
- W2087680319 cites W2323159882 @default.
- W2087680319 cites W2323272706 @default.
- W2087680319 cites W2325032460 @default.
- W2087680319 cites W2325289078 @default.
- W2087680319 cites W2325391126 @default.
- W2087680319 cites W2328558817 @default.
- W2087680319 cites W2331014115 @default.
- W2087680319 cites W2336107025 @default.
- W2087680319 cites W2513221845 @default.
- W2087680319 cites W2734415097 @default.
- W2087680319 doi "https://doi.org/10.1016/j.oregeorev.2007.05.001" @default.
- W2087680319 hasPublicationYear "2008" @default.
- W2087680319 type Work @default.
- W2087680319 sameAs 2087680319 @default.
- W2087680319 citedByCount "38" @default.
- W2087680319 countsByYear W20876803192012 @default.
- W2087680319 countsByYear W20876803192013 @default.
- W2087680319 countsByYear W20876803192014 @default.
- W2087680319 countsByYear W20876803192015 @default.
- W2087680319 countsByYear W20876803192016 @default.
- W2087680319 countsByYear W20876803192017 @default.
- W2087680319 countsByYear W20876803192018 @default.
- W2087680319 countsByYear W20876803192019 @default.
- W2087680319 countsByYear W20876803192020 @default.
- W2087680319 countsByYear W20876803192021 @default.
- W2087680319 countsByYear W20876803192022 @default.
- W2087680319 countsByYear W20876803192023 @default.
- W2087680319 crossrefType "journal-article" @default.
- W2087680319 hasAuthorship W2087680319A5000735302 @default.
- W2087680319 hasAuthorship W2087680319A5009254056 @default.
- W2087680319 hasAuthorship W2087680319A5022699229 @default.
- W2087680319 hasAuthorship W2087680319A5032383381 @default.
- W2087680319 hasAuthorship W2087680319A5036525960 @default.
- W2087680319 hasAuthorship W2087680319A5040727181 @default.
- W2087680319 hasAuthorship W2087680319A5046735064 @default.
- W2087680319 hasAuthorship W2087680319A5051917023 @default.
- W2087680319 hasAuthorship W2087680319A5064128211 @default.
- W2087680319 hasAuthorship W2087680319A5077713973 @default.
- W2087680319 hasAuthorship W2087680319A5077866276 @default.
- W2087680319 hasAuthorship W2087680319A5078535087 @default.
- W2087680319 hasAuthorship W2087680319A5078563658 @default.
- W2087680319 hasAuthorship W2087680319A5087643758 @default.
- W2087680319 hasConcept C109007969 @default.
- W2087680319 hasConcept C127313418 @default.
- W2087680319 hasConcept C146588470 @default.
- W2087680319 hasConcept C150999391 @default.
- W2087680319 hasConcept C151730666 @default.
- W2087680319 hasConcept C167284885 @default.
- W2087680319 hasConcept C171701179 @default.
- W2087680319 hasConcept C173776410 @default.
- W2087680319 hasConcept C17409809 @default.
- W2087680319 hasConcept C18142444 @default.
- W2087680319 hasConcept C195081551 @default.
- W2087680319 hasConcept C23295444 @default.