Very few zircon-bearing, kimberlite-hosted mantle eclogite xenoliths have been identified to date; however, the zircon they contain is crucial for our understanding of subcratonic lithospheric mantle evolution and eclogite genesis. In this study, we constrain the characteristics of zircon from mantle eclogite xenoliths based on existing mineralogical and geochemical data from zircons from different geological settings, and on the inferred origin of mantle eclogites. Given the likely origin and subsequent evolution of mantle eclogites, we infer that the xenoliths can contain zircons with magmatic, metamorphic and xenogenic (i.e. kimberlitic zircon) origins. Magmatic zircon can be inherited from low-pressure mafic oceanic crust precursors, or might form during direct crystallization of eclogites from primary mantle-derived melts at mantle pressures. Metamorphic zircon within mantle eclogites has a number of possible origins, ranging from low-pressure hydrothermal alteration of oceanic crustal protoliths to metasomatism related to kimberlite magmatism. This study outlines a possible approach for the identification of inherited magmatic zircon within subduction-related mantle eclogites as well as xenogenic kimberlitic zircon within all types of mantle eclogites. We demonstrate this approach using zircon grains from kimberlite-hosted eclogite xenoliths from the Kasai Craton, which reveals that most, if not all, of these zircons were most likely incorporated as a result of laboratory-based contamination.

中文翻译：

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地幔榴辉岩包体中的锆石：综述

迄今为止，很少有含锆石、以金伯利岩为主的地幔榴辉岩捕虏体被发现；然而，它们所含的锆石对于我们理解克拉通下岩石圈地幔演化和榴辉岩成因至关重要。在这项研究中，我们根据来自不同地质环境的锆石的现有矿物学和地球化学数据以及推断的地幔榴辉岩成因，对来自地幔榴辉岩捕虏体的锆石特征进行了限制。鉴于地幔榴辉岩的可能起源和随后的演化，我们推断捕虏体可能包含具有岩浆、变质和异种（即金伯利岩锆石）成因的锆石。岩浆锆石可以从低压镁铁质洋壳前体中继承，也可能在地幔压力下原始地幔衍生熔体的榴辉岩直接结晶过程中形成。地幔榴辉岩中的变质锆石有许多可能的起源，从大洋地壳原岩的低压热液蚀变到与金伯利岩岩浆作用有关的交代作用。本研究概述了一种可能的方法，用于鉴定与俯冲相关的地幔榴辉岩中的遗传岩浆锆石以及所有类型的地幔榴辉岩中的异种金伯利岩锆石。我们使用来自开赛克拉通的以金伯利岩为主体的榴辉岩捕虏体中的锆石颗粒演示了这种方法，这表明大多数（如果不是全部）这些锆石很可能是由于实验室污染而掺入的。从大洋地壳原岩的低压热液蚀变到与金伯利岩岩浆作用有关的交代作用。本研究概述了一种可能的方法，用于鉴定与俯冲相关的地幔榴辉岩中的遗传岩浆锆石以及所有类型的地幔榴辉岩中的异种金伯利岩锆石。我们使用来自开赛克拉通的以金伯利岩为主体的榴辉岩捕虏体中的锆石颗粒演示了这种方法，这表明大多数（如果不是全部）这些锆石很可能是由于实验室污染而掺入的。从大洋地壳原岩的低压热液蚀变到与金伯利岩岩浆作用有关的交代作用。本研究概述了一种可能的方法，用于鉴定与俯冲相关的地幔榴辉岩中的遗传岩浆锆石以及所有类型的地幔榴辉岩中的异种金伯利岩锆石。我们使用来自开赛克拉通的以金伯利岩为主体的榴辉岩捕虏体中的锆石颗粒演示了这种方法，这表明大多数（如果不是全部）这些锆石很可能是由于实验室污染而掺入的。