You must collect things for reasons you don't yet understand.ĭaniel J.
IUGS ULTRAMAFIC CLASSIFICATION BLANK TERNARY DIAGRAM SERIES
PART VI: STONY METEORITESMETAMORPHIC FACIES SERIES The diogenite classification ternary diagram shown below is from Wittke et al. An extension of their scheme was suggested by Wittke et al.
The diogenite classification scheme and data used on this page are adapted fromīeck and McSween Jr., MAPS, vol. The formation of these diogenite crustal intrusions and the metasomatism process that affected their orthopyroxene composition occurred after the removal of a Ca-rich melt to produce the eucritic crust. They determined that the compositional diversity among diogenites is caused primarily by variability in the oxygen fugacity (ΔIW ≡.6 to ≡.4) induced by sulfidation reactions (reduction of olivine by sulfer to produce troilite and orthopyroxene) within individual magma chambers. It is thought that these two lithologies occur in varying amounts among the different diogenites as a result of brecciation and mixing, sometimes forming polymict diogenites containing olivine with two pyroxenes.Īn alternative scenario was proposed by Mitchell and Tomkins (2019) based on data from a study of 200 diogenites. Of these two lithologies, one consists of olivine + magnesian orthopyroxene, and the other consists of ferroan orthopyroxene. ALH 85015, LEW 88008, NWA 1239, NWA 1648, NWA 4473, NWA 6945 )ĭiagram credit: Irving et al., 47th LPSC, #2264 (2016)Īccording to Beck and McSween (2010), diogenites represent two separate ultramafic lithologies formed by fractional crystallization in multiple plutons. The diagram has been slightly modified by increasing the MgO value by 13. POLYMICT: dunite ± harzburgite ± orthopyroxenite ± eucrite (<10 vol%) Among the various diagrams that we have been used, the CaO-MgO1.3-Al 2 O 3 diagram, previously used by for the distinction between ultramafic and alkaline lamprophyres, has allowed a better separation of the defined classes. NORITIC: orthopyroxene + 10 vol% plagioclase OLIVINEORTHOPYROXENITIC: orthopyroxene + 10≤0 vol% olivine HED (Vesta) material of ultramafic composition (olivine+orthopyroxene ≥90 vol%)ĭIOGENITES (6 subclasses known based on modal mineralogy)ġ. PART VI: STONY METEORITESMETAMORPHIC FACIES SERIES DIOGENITES PART V: ENSTATITE CHONDRITESSUBGROUP CLASSIFICATION
PART III: MARTIAN METEORITESGEOCHEMICAL CLASSIFICATION PART II: PRIMITIVE ACHONDRITES, ACHONDRITES, STONY-IRONS, IRONS PART IV PART I: CHONDRITES, METACHONDRITES
It graphically depicts the ratios of the three variables as positions in an equilateral triangle.It is used in physical chemistry, petrology, mineralogy, metallurgy, and other physical sciences to show the compositions of systems. A Systematic Classification of Meteorites Part IV To display this page you need a browser with JavaScript support.Ī SYSTEMATIC CLASSIFICATION OF METEORITES A ternary plot, ternary graph, triangle plot, simplex plot, Gibbs triangle or de Finetti diagram is a barycentric plot on three variables which sum to a constant.
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