拉曼光谱在划分普通球粒陨石化学群及冲击变质程度中的应用  

Application of Raman spectroscopy to classification of chemical groups and impact metamorphism of ordinary chondrites

作　　者：陈燕 夏志鹏[3,4,5] 张亦恺[3,4,5] 林书宇 陈洪 张兆峰 潘瑜 CHEN Yan;XIA Zhipeng;ZHANG Yikai;LIN Shuyu;CHEN Hong;ZHANG Zhaofeng;PAN Yu(School of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China;Research Center for Planetary Science,Chengdu University of Technology,Chengdu 610059,China;Institution of Meteorites and Planetary Materials Research,Guilin University of Technology,Guilin 541006,China;Key Laboratory of Planetary Geological Evolution of Guangxi Provincial Universities,Guilin University of Technology,Guilin 541006,China;Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,Guilin University of Technology,Guilin 541006,China)

机构地区：[1]成都理工大学地球科学学院,成都610059 [2]成都理工大学行星科学国际研究中心,成都610059 [3]桂林理工大学陨石与行星物质研究中心,广西桂林541006 [4]桂林理工大学行星地质演化广西高校重点实验室,广西桂林541006 [5]桂林理工大学广西隐伏金属矿产勘查重点实验室,广西桂林541006

出　　处：《桂林理工大学学报》2023年第4期559-569,共11页Journal of Guilin University of Technology

基　　金：中国科学院先导专项B类项目(XDB41000000);国家自然科学基金项目(42203048;41776196);广西自然科学基金项目(2022GXNSFAA035567;2021GXNSFBA075061)。

摘　　要：平衡型普通球粒陨石的化学群和冲击变质程度是判断陨石母体特征的重要指标,常根据其矿物组合、成分和结构特征等来确定。激光拉曼光谱作为一种无损快速分析技术,被广泛用于矿物成分的半定量分析和晶体结构判定。Northwest Africa(NWA)15006为一块普通球粒陨石,橄榄石(平均Fa_(25.4),PMD=2.9)和辉石(平均Fs_(21.4),PMD=4.5)成分相对均一,被划分为L4型。在NWA 15006岩石学和矿物学研究基础上,对橄榄石、辉石、斜长石及磷酸盐矿物进行了拉曼光谱分析,获得橄榄石和辉石的特征拉曼峰位(X_A和X_B)与成分(Fa和Fs)的对应关系:H、L和LL群普通球粒陨石中橄榄石的X_A分别为821.4~822.1 cm^(-1)、820.4~821.0 cm^(-1)和819.4~820.4 cm^(-1);辉石的X_B分别为680.3~681.5 cm^(-1)、679.0~680.0 cm^(-1)和677.8~679.0 cm^(-1)。利用对应特征峰,能够较为准确且快速划分NWA 15006属于L群。斜长石的拉曼特征峰为508.7和476.7 cm^(-1)、陨磷钙钠石为956.9和972.6 cm^(-1)、磷灰石为958.9 cm^(-1),结合矿物谱峰与压力变化相关关系,三者均显示受到较弱冲击,所受冲击压力小于6.8 GPa,与通过岩石学特征判断的冲击程度S2较一致。以上分析说明,通过典型矿物的拉曼光谱划分普通球粒陨石化学群和冲击变质程度是可行的,本工作为陨石分类提供了一种新的手段。The chemical group and impact metamorphism degree of balanced ordinary chondrites are important indicators to judge the characteristics of the parent body of meteorites,which are often determined according to the mineral association,composition and structural characteristics.Laser Raman spectroscopy,as a nondestruc-tive and rapid analysis technique,is widely used in semi-quantitative analysis of mineral composition and crystal structure determination.Northwest Africa(NWA)15006 is an ordinary chondrite with homogeneous composition of olivine(avg.Fa_(2)5.4,PMD=2.9)and pyroxene(avg.Fs21.4,PMD=4.5)and is classified as L4.Based on the petrological and mineralogical study of NWA 15006,this paper analyzes olivine,pyroxene,plagioclase and phosphate minerals by Raman spectroscopy,the corresponding relationship between characteristic Raman peak positions(XA and XB)and composition(Fa and Fs)of olivine and pyroxene was obtained.The XA of olivine in the H,L and LL chondrites are 821.4-822.1 cm^(-1),820.4-821.0 cm^(-1) and 819.4-820.4 cm^(-1),respectively.The XB of pyroxene is 680.3-681.5 cm^(-1),679.0-680.0 cm^(-1) and 677.8-679.0 cm^(-1),respectively.By using corresponding characteristic peaks,NWA 15006 can be accurately and quickly classified into L group.The characteristic Raman peaks are 508.7 and 476.7 cm^(-1) for plagioclase,956.9 and 972.6 cm^(-1) for merrillite,and 958.9 cm^(-1) for apatite.Combined with the relationship between mineral Raman spectral peaks and pressure changes,all three of them are weakly impacted,with the impact pressure<6.8 GPa.It is consistent with the impact degree S2 judged by petrological characteristics.The above analysis shows that it is feasible to classify the chemical group and impact metamorphism degree of ordinary chondrites by Raman spectra of typical miner-als,which provides a new means for the classification of meteorites.

关 键 词：普通球粒陨石 拉曼光谱 化学群 冲击变质 NWA 15006 

分 类 号：P185.83[天文地球—天文学] O657.37[理学—分析化学]