Calc-aluminous insets in olivine of the Sharps chondrite

抄録

<jats:title>Summary</jats:title><jats:p>A 250 µm olivine crystal in Sharps contains 1 to 5 µm insets identified by microprobe analysis as ferroan monticellite, spinel, and fassaite with average compositions: olivine (host), (Fe<jats:sub>0·44</jats:sub>Mg<jats:sub>1·51</jats:sub>Ca<jats:sub>0·05</jats:sub>) (Si<jats:sub>0·99</jats:sub>Al<jats:sub>0·01</jats:sub>)O<jats:sub>4</jats:sub>; ferroan monticellite, (Ca<jats:sub>0·89</jats:sub>Fe<jats:sub>0·41</jats:sub>Mg<jats:sub>0·66</jats:sub>) (Si<jats:sub>1·00</jats:sub>Al<jats:sub>0·02</jats:sub>)O<jats:sub>4</jats:sub>; spinel, (Fe<jats:sub>0·41</jats:sub>Mg<jats:sub>0·59</jats:sub>)(Fe<jats:sub>0·06</jats:sub><jats:sup>3+</jats:sup>Cr<jats:sub>0·23</jats:sub>Al<jats:sub>1·69</jats:sub>Si<jats:sub>0·01</jats:sub>Ti<jats:sub>0·01</jats:sub>)O<jats:sub>4</jats:sub>; and fassaite, Ca<jats:sub>0.96</jats:sub>(Fe<jats:sub>0·01</jats:sub>Mg<jats:sub>0·59)</jats:sub>(Al<jats:sub>0·18</jats:sub>Ti<jats:sub>0·07</jats:sub>Fe<jats:sub>0·16</jats:sub><jats:sup>3+</jats:sup>)(Si<jats:sub>1·53</jats:sub>Al<jats:sub>0·47</jats:sub>)O<jats:sub>6</jats:sub>. Textural and experimental data suggest early crystallization of spinel from a calcic olivine melt, exsolution of ferroan monticellite from the host olivine, and reaction of spinel and ferroan monticellite to form fassaite. The severe depletion of alkalies and silica in this crystal suggests it is a residue from vapour fractionation.</jats:p>

収録刊行物

被引用文献 (2)*注記

もっと見る

キーワード

詳細情報

問題の指摘

ページトップへ