Abstract

Esseneite from ultramafic xenoliths in dacite flow of the Ten’-01 paleovolcano at the Lena–Vilyui watershed, East Yakutia has been studied. The empirical formula of the mineral has been obtained using electron microprobe analysis: \({\text{C}}{{{\text{a}}}_{{0.99}}}{\text{Fe}}_{{0.52}}^{{3 + }}{\text{M}}{{{\text{g}}}_{{0.32}}}{\text{Fe}}_{{0.06}}^{{2 + }}{\text{T}}{{{\text{i}}}_{{0.05}}}{\text{Mn}}_{{0.01}}^{{2 + }}{\text{A}}{{{\text{l}}}_{{0.71}}}{\text{S}}{{{\text{i}}}_{{1.34}}}{{{\text{O}}}_{6}}\). Its crystal structure has been refined on the basis of the single crystal X-ray diffraction data, (R = 0.0152). The resulting crystal chemical formula is: \(^{{Ca}}{\text{C}}{{{\text{a}}}^{M}}{{\left( {{\text{Fe}}_{{0.48}}^{{3 + }}{\text{M}}{{{\text{g}}}_{{0.33}}}{\text{T}}{{{\text{i}}}_{{0.05}}}{\text{A}}{{{\text{l}}}_{{0.14}}}} \right)}^{T}}({\text{S}}{{{\text{i}}}_{{1.28}}}{\text{A}}{{{\text{l}}}_{{0.68}}}{\text{Fe}}_{{0.04}}^{{3 + }}){{{\text{O}}}_{6}}\). The monoclinic unit-cell parameters are: a = 9.7610(12), b = 9.8223(8), c = 5.3360(5) Å, β = 105.92(1), V = 441.89(8) ų, Z= 4, space group C2/c. The distribution of atoms over positions in the crystal structures of the Ca–Fe–Al clinopyroxenes and coordination polyhedron distortions, which reflect the formation conditions of the minerals, have been analyzed. The Yakutia esseneite has been formed in a highly oxidizing environment at 1200–950°C and approximate pressure of 2 kbar.

中文翻译：

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Dacite Lavas中的Xenoliths的真石：晶体结构和成因

摘要

研究了东雅库特地区Lena-Vilyui流域的Ten'-01古磷矿的超镁铁质异质岩中的钙铝石。矿物的经验公式已使用电子探针分析获得：\（{\ text {C}} {{{\ text {a}}} _ {{0.99}}} {\ text {Fe}} _ {{ 0.52}} ^ {{{3 +}} {\ text {M}} {{{\ text {g}}} _ {{0.32}}} {\ text {Fe}} _ {{0.06}} ^ {{ 2 +}} {\ text {T}} {{{\ text {i}}} _ {{0.05}}} {\ text {Mn}} _ {{0.01}} ^ {{2 +}} {\文本{A}} {{{\文本{l}}} _ {{0.71}}} {\文本{S}} {{{\文本{i}}} _ {{1.34}}} {{{\ text {O}}} _ {6}} \）。根据单晶X射线衍射数据，已精炼了其晶体结构（R = 0.0152）。生成的晶体化学式为：\（^ {{Ca}} {\ text {C}} {{{\ text {a}}} ^ {M}} {{\ left（{{\ text {Fe}} _ {{0.48}} ^ {{3 +}} {\ text {M}} {{{\ text {g}}} _ {{0.33}}} {\ text {T}} {{{\ text {i}}} __ { 0.05}}} {\ text {A}} {{{\ text {l}}} _ {{0.14}}}} \ right）} ^ {T}}（{\ text {S}} {{{\文字{i}}} _ {{1.28}}} {\文字{A}} {{{\文字{l}}} _ {{0.68}}} {\文字{Fe}} _ {{0.04}} ^ {{{3 +}}）{{{\ text {O}}} _ {6}} \）。单斜晶系晶胞参数为：A = 9.7610（12），B = 9.8223（8），C ^ = 5.3360（5），β= 105.92（1），V = 441.89（8）埃³，Ž = 4，空间组C 2 / c。分析了Ca-Fe-Al斜茂铁晶体结构中原子在各个位置上的分布以及反映矿物形成条件的配位多面体畸变。雅库特（Yakutia）硒沸石是在高度氧化的环境中于1200–950°C和约2 kbar的压力下形成的。