Abstract—A study of the morphology, composition, and age (by the CHIME and LA–ICP–MS methods) of monazite from the Ichet’yu occurrence, located in Middle Timan, revealed some principal differences in the typomorphic features and genesis of its two varieties. The common yellow monazite from this occurrence is monazite-(Ce), in which the content of La is higher than that of Nd. The time of its crystallization (recrystallization) is estimated by the CHIME method as 518 ± 40 Ma. Kularite (a grayish-brown globular variety of monazite, in which Nd is higher than La) was dated at 978 ± 31 Ma. The age of some kularite grains is 520 ± 27 Ma, which may be interpreted as the date of a hydrothermal event that resulted in the simultaneous recrystallization of both monazite and kularite. However, these two monazite varieties were formed in two completely different sources and were combined in the mineral parasteresis of the Ichet’yu occurrence. The CHIME age of monazite from the Ichet’yu occurrence that belongs to two intervals (500–600 and 960–1000 Ma) is consistent with the age determined in the same monazite grains using the LA–ICP–MS technique.

摘要－对位于蒂曼中部伊切尤地区的独居石形态，组成和年龄（通过CHIME和LA-ICP-MS方法）的研究表明，这两个地区的错字特征和成因存在一些主要差异品种。这种情况下常见的黄色独居石为独居石-（Ce），其中La的含量高于Nd。通过CHIME方法估计其结晶（再结晶）时间为518±40Ma。Kularite（一种灰棕色球状独居石，其Nd高于La）的年代为978±31 Ma。某些钾钙石晶粒的年龄为520±27 Ma，这可以解释为水热事件的发生日期，水热事件导致独居石和钾钙石同时重结晶。然而，这两个独居石变种是在两个完全不同的来源中形成的，并结合到了伊切特尤矿的矿物寄生中。Ichet'yu事件中独居石的CHIME年龄属于两个区间（500-600和960-1000 Ma），与使用LA-ICP-MS技术在同一独居石晶粒中确定的年龄一致。