地球深处形成含硼金刚石的可行机制  

A viable mechanism to form boron-bearing diamonds in deep Earth

作　　者：刘思瑜 陆文成 张晓冉 宋京岩 吕健 刘晓兵 王彦超 陈长风 马琰铭 Siyu Liu;Wencheng Lu;Xiaoran Zhang;Jingyan Song;Jian Lü;Xiaobing Liu;Yanchao Wang;Changfeng Chen;Yanming Ma(Key Laboratory of Material Simulation Methods and Software of Ministry of Education,College of Physics,Jilin University,Changchun 130012,China;State Key Laboratory of Superhard Materials,College of Physics,Jilin University,Changchun 130012,China;Laboratory of High Pressure Physics and Material Science,School of Physics and Physical Engineering,Qufu Normal University,Qufu 273100,China;Department of Physics and Astronomy,University of Nevada,Las Vegas,NV 89154,USA;International Center of Future Science,Jilin University,Changchun 130012,China)

机构地区：[1]Key Laboratory of Material Simulation Methods and Software of Ministry of Education,College of Physics,Jilin University,Changchun 130012,China [2]State Key Laboratory of Superhard Materials,College of Physics,Jilin University,Changchun 130012,China [3]Laboratory of High Pressure Physics and Material Science,School of Physics and Physical Engineering,Qufu Normal University,Qufu 273100,China [4]Department of Physics and Astronomy,University of Nevada,Las Vegas,NV 89154,USA [5]International Center of Future Science,Jilin University,Changchun 130012,China

出　　处：《Science Bulletin》2023年第13期1456-1461,M0004,共7页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(T2225013,12174142,11904142,and 11534003);the Program for Jilin University Science and Technology Innovative Research Team(2021TD–05)。

摘　　要：近年来,以“希望之钻”为代表天然蓝色钻石(蓝钻)的形成机制引起科学界和大众的广泛兴趣.天然蓝钻是形成于地球最深处的珍贵矿物,含约0.011~10μg/g棚杂质.现行地球化学模型表明地球内部硼元素主要富集于大陆和大洋地壳,极难进入地球内部的下地幔深度.蓝钻的存在为地球下地幔环境中存在硼元素提供了有力证据,然而其地质起源与循环机制是当前领域内亟待解决的科学难题之一.在本研究中,我们提出金属硼化物随地球板块运动进入下地幔深处,在高温高压环境下与碳酸盐发生氧化还原反应,从而形成蓝钻的物理机制.通过第一性原理计算提出了多种可能形成蓝钻的化学反应途径,并在下地幔压力与温度条件下(22.5 GPa,2100 K),利用CaCO_(3)和FeB的直接氧化还原反应,成功制备“类天然”蓝钻.这一发现揭示了地球深处蓝钻形成之谜,并为进一步深入探索地球内部的物质循环和矿物形成机制提供了新思路.Boron is considered extremely depleted inside Earth's mantle.It is therefore a great challenge to elucidate the prevalence of boron impurity seen in sublithospheric diamonds,especially in identifying the boron source and the mechanism for its incorporation into these enigmatic diamonds.Here,we unveil a pathway for the crystallization of boron-bearing diamonds via redox reactions of carbonates and borides at pressure–temperature conditions relevant to the Earth's lower mantle.We present computational results along with pertinent experimental evidence for a genesis of boron-bearing diamonds via the redox reaction of CaCO_(3)and FeB at 22.5 GPa and 2100 K,corresponding to the geological conditions at the top of the lower mantle.The present findings offer a viable mechanism for the formation of boron-bearing diamonds deep inside the Earth's mantle.

关 键 词：Boron-bearing diamonds indeep Earth First-principlescalculations High-pressureandhigh-temperature experimental synthesis Redoxreactions 

分 类 号：P619.241[天文地球—矿床学]