摘要
山东蒙阴常马庄、西峪和坡里三个金伯利岩带的金刚石含矿性存在显著差异,而三个矿带金刚石的矿物学特征是否亦存在差异还不清楚。本文整理和统计前人研究的山东蒙阴10万余粒金刚石数据,发现三个金伯利岩带金刚石的晶体颜色、粒度、晶体形态及表面形貌和包裹体等具有明显不同的特征:(1)51484粒常马庄金刚石以淡黄色为主,其次为无色和浅黄棕色,粒径范围0.5~2.0 mm比例最高,大于2.0 mm超过7%;53108粒西峪金刚石以无色为主,其次为淡黄色和褐色,0.5~1.0 mm粒径占比最高,大于2.0 mm的比例约4%;坡里405粒金刚石中,无色比例达70%以上,淡黄色次之,粒径均在1 mm以下。(2)常马庄4807粒金刚石以菱形十二面体为主,其次为八面体、八面体与菱形十二面体聚晶;单晶约占85%;西峪2479粒金刚石以八面体为主,其次为曲面十二面体,连生体较多,约占30%;坡里405粒金刚石以单晶阶梯状八面体为主,双晶和连生体很少。(3)4807粒常马庄金刚石的表面形貌类型最丰富;2479粒西峪金刚石中生长丘、倒三角凹坑、生长阶梯表面形貌发育比例相对较高,405粒坡里金刚石主要发育三角形凹坑、生长阶梯、生长丘。(4)西峪岩带红旗23号2粒金刚石中存在石墨和橄榄石包裹体,且橄榄石包裹体上覆石墨斑点,与常马庄已发现的橄榄石包裹体具有相似特征。利用西峪金刚石中橄榄石包裹体的拉曼位移数据计算源区压力为5.09 GPa和5.26 GPa,形成深度分别为168 km、174 km的克拉通地幔。(5)首次测定坡里岩带10粒金刚石的傅里叶红外光谱显示金刚石类型为ⅠaA和ⅠaAB型。
Significant differences in diamond mineralization are observed in the three diamondiferous kimberlite belts of Changmazhuang, Xiyu and Poli in the Mengyin cluster, Shandong Province. However, it is ambiguous whether there are distinctive mineralogical characteristics of diamonds in these three belts. In this review, we systematically summarize and mineralogically compare previous data of more than 100000 diamond grains from geological survey reports related to the three belts, and propose that the crystal-color, grain-size, morphology and inclusions of three-belt hosted-diamonds are clearly identifiable.(1) The 51484 diamond grains from the Changmazhuang kimberlite belt are mainly light yellow in color, followed by colorless and light yellow-brown, the highest proportion of grain-size ranges from 0.5 mm to 2.0 mm, and over 7% are larger than 2.0 mm. The 53108 diamond grains from the Xiyu kimberlite belt are briefly colorless, followed by light yellow and brown colors. The grain size of 0.5~1.0 mm accounts for the highest proportion, while the proportion larger than 2.0 mm is about 4%. While 405 diamond grains from the Poli kimberlite belt are dominantly colorless with the proportion of over 70% followed by light yellow, all grain sizes are below 1 mm.(2) Rhombic dodecahedron is dominant in the 4807 Changmazhuang diamonds, morphologically followed by octahedrons, glomerocryst of octahedrons and rhombic dodecahedrons. Single crystals account for about 85%. By contrast, octahedrons are main crystal form in the 2479 Xiyu diamonds, followed by curved dodecahedrons, and the connected crystals account for about 30%. The 405 Poli diamonds are dominated by single-crystal stepped octahedron, with few twin and intergrowth crystals.(3) The 4807 Changmazhuang diamonds have the most abundant types of surface morphology. The proportion of growth mounds, inverted triangular pits and growth steps is relatively high in the 2479 Xiyu diamonds. Comparably, the 405 Poli diamonds mainly develop triangular pits, growth steps and growth hills.(4) There are graphite and olivine inclusions in two diamond grains from the Hongqi No.23 mine in the Xiyu rock belt, and olivine inclusions are covered with graphite spots, which have characteristics similar to olivine inclusions found in the Changmazhuang area. Based on the Raman displacement data of olivine inclusions from the Xiyu diamonds, the source pressure is calculated to be 5.09 GPa and 5.26 GPa, forming cratonic mantle with depth of 168 km and 174 km respectively.(5) The Fourier infrared spectrum of ten diamonds in the Poli rock belt for the first time shows that the diamond types are IaA and IaAB.
作者
吕青
刘飞
褚志远
葛跃进
刘潇
焦永鑫
Lü Qing;LIU Fei;CHU Zhiyuan;GE Yuejin;LIU Xiao;JIAO Yongxin(The 7th Institute of Geology&Mineral Ex ploration of Shangdong Province.Academician Work station of Diamond Mineralization Mechanisn and Ex ploration in Shandong Province,Linyi,Shangdong 276006,China;Key Laboratory of Diamond Mineralixation Mechanism and Ex ploration,Shandong Provincial Bureau of Geology&Mineral Resources,Linyi,Shangdong 276006,China;CARMA,Key Laboratory of Deep-Earth Dynamics,Instilute of Geology,Chinese Acdemy of Geological Sciences,Beijing 100037,China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2022年第4期1225-1238,共14页
Acta Geologica Sinica
基金
山东省地矿局局控项目(编号202012)
山东地矿七院科技性创新项目(编号QDKY202005,QDKY202007)
山东省重大科技创新工程项目(编号2017CXGC1607)
南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(编号GML2019ZD0201)联合资助的成果。
关键词
金刚石
颜色
晶体形态
包裹体
拉曼光谱
傅里叶红外光谱
山东蒙阴
diamond
color
crystal morphology
inclusion
Raman spectrum
FTIR
Mengyin cluster in Shandong Province
