基于红外光谱-拉曼光谱研究山东郯城砂矿的金刚石及包裹体类型  

A Study of Types of Diamonds and Inclusions in Tancheng Placer of Shandong Province Based on Infrared and Raman Spectroscopy

作　　者：吕青 焦永鑫 葛跃进 肖丙建 褚志远 刘淑桢 LU Qing;JIAO Yong-xin;GE Yue-jin;XIAO Bing-jian;CHU Zhi-yuan;LIU Shu-zhen(The 7th Institute of Geology&Mineral Exploration of Shandong Province,Linyi,Shandong 276006;Key Laboratory of Diamond Mineralization Mechanism and Exploration,Shandong Provincial Bureau of Geology&Mineral Resources,Linyi,Shandong 276006;Academician Workstation of Diamond Mineralization Mechanism and Exploration in Shandong Province,Linyi,Shandong 276006;Natural Resources Bureau of Luozhuang District,Linyi City,Shandong Province,Linyi,Shandong 276006)

机构地区：[1]山东省第七地质矿产勘查院,山东临沂276006 [2]山东省地质矿产勘查开发局金刚石成矿机理与探测重点实验室,山东临沂276006 [3]山东省金刚石成矿机理与探测院士工作站,山东临沂276006 [4]山东省临沂市罗庄区自然资源局,山东临沂276006

出　　处：《地球学报》2021年第6期895-906,共12页Acta Geoscientica Sinica

基　　金：山东省地质矿产勘查开发局局控项目(编号:202012);山东省第七地质矿产勘查院科技性创新项目(编号:QDKY202005);山东省重大科技创新工程项目(编号:2017CXGC1607)联合资助。

摘　　要：对山东郯城砂矿中的金刚石开展了傅里叶红外光谱和显微激光拉曼光谱的测试,结果显示,红外光谱均可见C-C的本征峰;绝大多数可见氮的吸收峰:双氮的吸收峰、聚合氮的吸收峰和氮片晶的吸收峰;部分可见氢的吸收峰:C-H的吸收峰、C-N的吸收峰和H2O的吸收峰。郯城金刚石以Ⅰa型金刚石为主,有ⅠaA、ⅠaB、ⅠaAB型,而Ⅱa型仅1粒;氮类型包括双氮(A心)、聚合氮(B心)及氮片晶(B’心),说明金刚石中的孤氮(C心)已经转化为双原子氮,但部分双原子氮未完成进一步的聚形。金刚石拉曼峰值集中在1131cm^(-1),拉曼位移漂移程度较小,说明金刚石内部应力发生小幅的变化。在郯城金刚石中首次发现柯石英包裹体,出现139cm^(-1)、152cm^(-1)、212cm^(-1)、272cm^(-1)、328cm^(-1)、356cm^(-1)、428cm^(-1)和529cm^(-1)左右的拉曼峰值。在1粒金刚石中柯石英包裹体数量多达十余个,直径几μm至几十μm,呈针状、哑铃状、浑圆状和短柱状等多种形态。郯城金刚石中柯石英包裹体的出现,可作为郯城地区存在榴辉岩型金刚石的可靠标志,也佐证了该地部分金刚石的来源可能和洋壳循环或者俯冲过程有关。镁橄榄石包裹体上覆分散的黑色石墨斑点,与山东蒙阴、辽宁和湖南金刚石中的镁橄榄石等不同种类包裹体具有相似特征,推测这些石墨斑点是晶体包裹体形成后,由于外部环境温压条件的变化产生。The test results of Fourier infrared spectroscopy and micro laser Raman spectroscopy of diamond in Tancheng of Shandong Province show that the intrinsic peak of C–C can be seen in infrared spectra of both methods. The absorption peaks of most visible nitrogen include the absorption peaks of diazonium, polymerized nitrogen and nitrogen wafer. Some hydrogen absorption peaks are visible: the absorption peaks of C–H, C–N and H;O. Tancheng diamonds are mainly type Ia diamonds, including type IaA, IaB, IaAB, and type IIa only possesses one grain;nitrogen types include dinitrogen(A center), polymeric nitrogen(B center) and nitrogen platelet(B’ center), indicating that the solitary nitrogen(C center) in diamond has been converted into diatomic nitrogen, but some atomic nitrogen has not completed further aggregation. The diamond Raman peak is concentrated at 1131cm^(-1), and the Raman displacement drift is small, indicating that the internal stress of diamond has changed slightly. Coesite inclusions were found for the first time in Tancheng diamond, whose Raman test peaks were 139cm^(-1), 152cm^(-1), 212cm^(-1), 272cm^(-1), 328cm^(-1), 356cm^(-1), 428cm^(-1)and 529cm^(-1).There are more than ten coesite inclusions in a single diamond, with diameters ranging from several μm to dozens of μm, exhibiting various shapes such as needle-shaped, dumbbell-shaped, round and short column-shaped forms.The presence of coesite inclusions in Tancheng diamonds may be a reliable indicator of the presence of eclogite-type diamonds in the Tancheng area, and also suggests that the origin of some of these diamonds must have been related to oceanic circulation or subduction processes. The black graphite spots on the inclusions of magnesium olivine have similar characteristics to those of different kinds of inclusions in diamonds from Mengyin of Shandong, Liaoning and Hunan. It is inferred that these graphite spots were caused by the change of temperature and pressure conditions of external environment after the formation of crystal i

关 键 词：金刚石 红外光谱 拉曼光谱 包裹体 柯石英 山东郯城 

分 类 号：P575.4[天文地球—矿物学]