Abstract

REE fractionation into cerium Ce_g (La–Eu) and yttrium Y_g (Gd–Lu) groups, as well as La_sg (La–Pr), Sm_sg (Nd–Eu), Gd_sg (Gd–Dy), and Yb_sg (Y, Ho–Lu) subgroups in xenotime and florencite crystals from the ore occurrence, Polar Urals, is considered. REE subgroups and other minor elements of the minerals form isomorphic complexes, among which are La_K [(La,Се,Pr)Al₃(P,As,Si)₂O₈(OH)₆] and Sm_K [(Nd,Sm,Eu,Gd,Sr,Ca)Al₃(P,S,Si)₂O₈(OH)₆] in florencite, and Gd_K [(Gd,Sm,Eu,Tb,Dy)(Р,Si)O₄] and Yb_K [(Y,Nd,Ho,Er,Yb,Lu,Sc,U)(Р,Аs,Si)О₄] in xenotime. The paper discusses the distribution of these complexes in zones of crystal growth and in the volume of crystals. The chemical compositions of simple forms of crystals are compared—namely, bipyramids and prisms of xenotime, as well as several rhombohedra of florencite. Mineral inclusions with the same compositions as xenotime and florencite hosting them are characterized and the reasons for their appearance are considered. Based on the sequence of the formation of minerals, evidence is provided for regular trends in lanthanide composition of phosphates upon their crystallization (increasing role off light lanthanides relative to heavy lanthanides). The mechanisms of crystal growth are investigated, including relative linear and volume growth rates of crystal faces, the formation of co-growth surfaces of different faces and individuals, and the nature of oscillatory and trend zoning. The existence of the tetrad effect in the lanthanide compositions of two minerals is verified.

中文翻译：

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Florencite 和 Xenotime 共生共生中振荡分区的性质和晶体生长机制

摘要

REE 分馏成铈 Ce _g (La-Eu) 和钇 Y _g (Gd-Lu) 基团，以及 La _sg (La-Pr)、Sm _sg (Nd-Eu)、Gd _sg (Gd-Dy) 和考虑了来自极地乌拉尔矿区的钇矿和萤石晶体中的Yb _{sg (Y, Ho-Lu) 亚群。}稀土亚群与矿物的其他微量元素形成同形配合物，其中有 La _K [(La,Се,Pr)Al ₃ (P,As,Si) ₂ O ₈ (OH) ₆ ] 和 Sm _K [(Nd, Sm,Eu,Gd,Sr,Ca)Al ₃ (P,S,Si) ₂ O ₈ (OH) ₆] 和 Gd _K [(Gd,Sm,Eu,Tb,Dy)(Р,Si)O ₄ ] 和 Yb _K [(Y,Nd,Ho,Er,Yb,Lu,Sc,U)(Р ,Аs,Si)О ₄] 在 xenotime。本文讨论了这些配合物在晶体生长区和晶体体积中的分布。比较了简单形式晶体的化学成分，即磷钇矿的双锥体和棱柱体，以及萤石的几种菱面体。表征了与托管它们的磷钇矿和萤石具有相同成分的矿物包裹体，并考虑了它们出现的原因。基于矿物形成的顺序，提供了磷酸盐在结晶时镧系元素组成的规律趋势的证据（轻镧系元素相对于重镧系元素的作用增加）。研究了晶体生长的机制，包括晶面的相对线性和体积生长速率，不同面孔和个体的共生面的形成，以及振荡和趋势分区的性质。验证了两种矿物的镧系元素组成中存在四联体效应。