Abstract

The pyrochlore-group minerals in ongonite and zwitter of the Verkhneurmiysky granite pluton in the Badzhal district, Russian Far East are reported. The composition, genesis, and crystallization sequence are characterized. Three rare species of pyrochlore, pyrochlore-I and pyrochlore-II in ongonite, and pyrochlore-III in zwitter are found for the first time in the Russian Far East. Pyrochlore-I is a possible new member of the pyrochlore group, bismuth-bearing “oxyferropyrochlore”; pyrochlore-II is an uranium-bearing and iron-bearing hydrokenopyrochlore; and pyrochlore-III is a lead-and iron-bearing hydrokenopyrochlore. All three pyrochlore species result from an alteration of early accessory minerals: niobium wolframite, samarskite, ishikawaite, wolframoixiolite, scheelite, and fergusonite. The Far East pyrochlore is characterized by extremely high Ta, W, and Fe contents. Compositional variations in pyrochlore are caused by substitution of Nb, Ta, W at the B site of the crystal structure and exchange of U, Pb, Bi, and Fe at the A site. The Ta, Bi, and Th concentrations decrease during transition from the late magmatic to greisen stage; the mineral forming significance of Nb, W, U, Y, Pb, and H₂O increases as followed: Ta, Nb, Bi, Fe, Th, As, P, Ca, Ti → Nb, Ta, W, U, Fe, HREE, Sc, Mn, Na, H₂O → Nb, Pb, W, Fe, Y, H₂O.

中文翻译：

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俄罗斯远东地区Verkhneurmiysky Pluton的Ongonite和Zwitter中烧绿石类矿物的组成变化

摘要

据报道，俄罗斯远东地区Badzhal地区Verkhneurmiysky花岗岩岩体中的ongonite和zwitter中的烧绿石类矿物。表征组成，成因和结晶顺序。在俄罗斯远东地区首次发现了三种稀有的烧绿石，烧绿石-I和烧绿石-II和两性生物中的烧绿石-III。烧绿石-I是烧绿石族的一个可能的新成员，即含铋的“氧化铁草四氯”；烧绿石-II是一种含铀和含铁的氢氯氰。烧绿石-III是一种含铅和铁的氢氯吡氯。所有这三种烧绿石物种都来自早期辅助矿物的变化：铌黑钨矿，闪锌矿，石川石，黑钨矿，白钨矿和硅铁矿。远东烧绿石的特征在于极高的Ta，W和Fe含量。烧绿石中的组成变化是由Nb，Ta，W的取代引起的。晶体结构的B位和在A位交换U，Pb，Bi和Fe 。从岩浆晚期到格里森期过渡期间，Ta，Bi和Th的浓度降低。Nb，W，U，Y，Pb和H ₂ O的成矿意义如下：Ta，Nb，Bi，Fe，Th，As，P，Ca，Ti→Nb，Ta，W，U，Fe ，重稀土，钪，锰，钠，H ₂ O→铌，铅，钨，铁，Y，H ₂ O.