Ultradeep diamonds originate from deep subducted sedimentary carbonates

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• 作者：Jing Gao ; JingJing Niu ; Shan Qin ; Xiang Wu
• 关键词：Ultradeep diamond ; Carbonates ; Oceanic subduction ; Earth carbon cycle
• 刊名：Science China Earth Sciences
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：60
• 期：2
• 页码：207-217
• 全文大小：
• 刊物主题：Earth Sciences, general;
• 出版者：Science China Press
• ISSN：1869-1897
• 卷排序：60

文摘

Diamonds are renowned as the record of Earth’s evolution history. Natural diamonds on the Earth can be distinguished in light of genetic types as kimberlitic diamonds (including peridotitic diamonds and eclogitic diamonds), ultrahigh-pressure metamorphic diamonds and ophiolitic diamonds. According to the inclusion mineralogy, most diamonds originated from continental lithospheric mantle at depths of 140–250 km. Several localities, however, yield ultradeep diamonds with inclusion compositions that require a sublithospheric origin (>~250 km). Ultradeep diamonds exhibit distinctions in terms of carbon isotope composition, N-concentration, mineral inclusions and so on. The present study provides a systematic compilation concerning the features of ultradeep diamonds, based on which to expound their genesis affinity with mantle-carbonate melts. The diamond-parental carbonate melts are proposed to be stemmed from the Earth’s crust through subduction of oceanic lithosphere. Ultradeep diamonds are classified into a subgroup attaching to kimberlitic diamonds grounded by formation mechanism, and present connections in respect of carbon origin to eclogitic diamonds, ultrahigh-pressure metamorphic diamonds and ophiolitic diamonds.