文章基本信息

标题：Oceanic and super-deep continental diamonds share a transition zone origin and mantle plume transportation
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作者：Luc S. Doucet ; Zheng-Xiang Li ; Hamed Gamal El Dien 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2021
卷号：11
DOI：10.1038/s41598-021-96286-8
语种：English
出版社：Springer Nature
摘要：Rare oceanic diamonds are believed to have a mantle transition zone origin like super-deep continental diamonds. However, oceanic diamonds have a homogeneous and organic-like light carbon isotope signature (δ 13C − 28 to − 20‰) instead of the extremely variable organic to lithospheric mantle signature of super-deep continental diamonds (δ 13C − 25‰ to + 3.5‰). Here, we show that with rare exceptions, oceanic diamonds and the isotopically lighter cores of super-deep continental diamonds share a common organic δ 13C composition reflecting carbon brought down to the transition zone by subduction, whereas the rims of such super-deep continental diamonds have the same δ 13C as peridotitic diamonds from the lithospheric mantle. Like lithospheric continental diamonds, almost all the known occurrences of oceanic diamonds are linked to plume-induced large igneous provinces or ocean islands, suggesting a common connection to mantle plumes. We argue that mantle plumes bring the transition zone diamonds to shallower levels, where only those emplaced at the base of the continental lithosphere might grow rims with lithospheric mantle carbon isotope signatures.