Abstract

New mineralogical and isotope–geochemical data for zircon megacrysts (n = 48) from alluvium of Kholomolokh Creek (a tributary of the Ebelakh River) are reported. Using the geochemical classification schemes, the presence of zircons of kimberlitic and carbonatitic genesis was shown. The U–Pb dating of zircons revealed two major age populations: the Triassic (258–221 Ma, n = 18) and Jurassic (192–154 Ma, n = 30). Weighted mean ²⁰⁶Pb/²³⁸U ages allowed us to distinguish the following age stages: 155 ± 3, 161 ± 2, 177 ± 1.5, 183 ± 1.5, 190 ± 2, 233 ± 2.5, and 252 ± 4 Ma. It is suggested that the Ebelyakh diamonds could have been transported from the mantle depths by kimberlite, as well as by other related rocks, such as carbonatite, lamprophyre, lamproite, olivine melilitite, etc. Diamonds from the Ebelyakh placers most likely have polygenic native sources and may be associated with polychronous and multistage Middle Paleozoic and Mesozoic kimberlite and alkaline–ultrabasic magmatism in the eastern slope of the Anabar Shield (the Ebelyakh, Mayat, and Billyakh river basins).

中文翻译：

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Ebelyakh河流域（Anabar盾构的东坡）地区含钻石的砂岩区域中的多级和多级碱性中超生代岩浆作用的证据。

摘要

据报道，来自霍卢莫洛赫河（埃贝拉克河的支流）冲积层的锆石大晶体（n = 48）的新的矿物学和同位素地球化学数据。使用地球化学分类方案，显示了金伯利岩和碳酸盐岩成因的锆石的存在。锆石的U–Pb测年揭示了两个主要年龄人群：三叠纪（258–221 Ma，n = 18）和侏罗纪（192–154 Ma，n = 30）。加权平均值²⁰⁶ Pb / ²³⁸年龄允许我们区分以下年龄阶段：155±3、161±2、177±1.5、183±1.5、190±2、233±2.5和252±4 Ma。有人认为，Ebelyakh钻石可能是由金伯利岩以及其他相关岩石从地幔深处运走的，如碳酸盐岩，煌斑岩，萤石，橄榄石陨石等。来自Ebelyakh砂矿的钻石极有可能是多源天然来源可能与Anabar Shield东部斜坡（Ebelyakh，Mayat和Billyakh流域）的多期和多级中古生代和中生代金伯利岩以及碱性-超碱性岩浆作用有关。