Abstract

For most rare-metal pegmatite fields, two generations of granitic pegmatites are documented, namely, beryll-bearing (often with tantaloniobates and muscovite, which are inseparable from vein granites of the leucogranite complex), and Na-Li (Li, Ta, Cs, Be, and Sn) (LCT-pegmatites). The latter, in turn, subdivide into (i) a “multicomponent rare-metal type” with pegmatite zoning and main mineralization (large crystals of spodumene, tantalates, beryll, cassiterite, pollucite, petalite, and amblygonite) in the central parts of the respective bodies (Koktogai, Bernic Lake, Bikita, Karibib, Varutrask, Vishnyakovskoe, and others) and (ii) “albite-spodumene pegmatites” that compose multiple extended dikes that are devoid of pegmatite zoning and are grouped into fields of up to 10–15 km or more in length (Kings Mountain, Zavitinskoe, Gol’tsovoe, Kolmozero, Polmos-Tundrovoe, Tastyg, and others). For a number of deposits (e.g., Zavitinskoe, Vasin-Myl’k, and Shukbyul’), the occurrence of multicomponent rare-metal pegmatites in the “heads” of feeding dikes of “albite–spodumene pegmatites” is established. Any attempt to identify parent granites for “albite–spodumene pegmatites” is a priori futile, because these are not pegmatites, but granites, although specific ones (in fact, spodumene granites of the Allakha type). The purely terminological correction, granite instead of pegmatite, surprisingly has both scientific and forecasting implications. The scientific implications imply that, first, the problem about parent granites is solved and, second, the “pegmatite” status of “albite–spodumene pegmatites” no longer debated. These pegmatites correspond to the particular, spodumene–rare-metal–granite stage in the history of magmatism of certain pegmatite-bearing areas (the end of this stage was marked by the formation of true multicomponent pegmatites that are characteristic of only this stage). Regarding the forecast implications, it can be supposed that such multicomponent deposits as Koktogai, Bernic Lake, Bikita, Karibib, and Vishnyakovskoe are underlain by a suite of dikes comprised by spodumene-bearing rare-metal granites (i.e., an independent Li deposit), and multicomponent pegmatites are differentiates of these granites.

中文翻译：

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具有稀有金属伟晶岩的花岗岩系统

摘要

对于大多数稀有金属伟晶岩田，已记录了两代花岗岩伟晶岩，即含铍青石（通常与钽钛矿和白云母，这与白花岗岩体的脉状花岗岩密不可分）和Na-Li（Li，Ta，Cs ，Be和Sn）（LCT岩晶）。后者反过来又细分为（i）伟晶岩带和主要矿化作用的“多组分稀有金属类型”（锂辉石，钽酸盐，铍青铜，锡石，钙铝石，方铁矿，方铁矿和闪锌矿的大晶体）。 （Koktogai，Bernic Lake，Bikita，Karibib，Varutrask，Vishnyakovskoe等）的身体，以及（ii）由多个延展的堤防组成的“石辉石伟晶岩”，这些岩岩没有伟晶岩分区，最多可分为10个长度超过15公里（国王山，扎维京斯科，戈尔佐沃，科尔摩泽罗，Polmos-Tundrovoe，Tastyg等）。对于许多矿床（例如Zavitinskoe，Vasin-Myl'k和Shukbyul'），确定了在“ bitbit-spodumene伟晶岩”喂料堤坝的“头部”中出现了多组分稀有金属伟晶岩。任何试图将母体花岗岩识别为“阿尔比特-锂辉石伟晶岩”的尝试都是徒劳的，因为这些并非伟晶岩，但花岗岩，尽管是特定的（实际上是阿拉卡类型的锂辉石花岗岩）。纯粹的术语校正，花岗岩而不是伟晶岩，令人惊讶地具有科学和预测意义。科学意义意味着，首先，有关母体花岗岩的问题得到了解决，其次，不再讨论“套-锂辉石伟晶岩”的“辉石”状态。这些伟晶岩对应于某些含伟晶岩地区的岩浆作用史中的特殊锂辉石-稀有金属-花岗岩阶段（这一阶段的结束以真正的多组分伟晶岩的形成为标志，这只是该阶段的特征）。关于预测意义，可以假设这样的多组分矿床，如科克托加，伯尼奇湖，比基塔，卡里比卜，