摘要
金伯利岩型金刚石矿床是世界上重要的金刚石矿床类型:也是我国迄今所发现的唯一的金刚石原生矿床类型。本文阐述了我国金伯利岩分布的构造部位、时代、产状、与暗色岩类的关系、围岩及其蚀变特征、岩管的岩相特征、岩石类型及岩石化学特征,并指出了该类矿床的找矿标志。
Kimberlites have been found in eight provinces of China, namely Liaoning, Shandong, Guizou, Henan, Hubei, Shanxi, Hebei and Jilin, all located in North China platform and Yangtze platform; nevertheless, only kimberlites in Shandong and Liaoning provinces contain diamonds of economic significance. Isotopic dating and geological data reveal that kimberlites in China mainly occur in Paleozoic. In Guizhou, Hubei and Shanxi, kimberlites with very little or no diamonds are associated with lamproite, meymechite and minette. Kimberlite pipes observed at surface of Shandong and Liaoning are root facies and bottom facies of diatreme respectively.
Diamond-bearing kimberlites are richer in MgO+Cr_2O_3 + NiO but poorer in TiO_2+Al_2O_3+Na_2O+K_2O+P_2O5 as compared with diamond-free ones. The average content of compatible elements in kimberlites of China is Cr 846ppm, Ni 690ppm, Co 45ppm, Sc 19.96ppm, Cu 156ppm, and Zn 106ppm, and that of incompatible elements Ba 835ppm Sr 454ppm, Zv 308ppm, Nb 81ppm, Ta llppm,U 8.8ppm, Th 70ppm, Li 44.68ppm and Rb 29ppm. Lots of element pairs in kimberlites, i. e. Cr-Al, Ni-Co, Ni-Cr, Ni-V, Sc-Ti, Zn-Ti, Ba-Sr, Zr-Hf, Nb-Ta, U-Th and K-Rb, show positive correlation.
In diamond-rich kimberlites, pyrope and chrome-spinel are rich in Cr but poor in Al, ilmenite contains high Mg and Cr, clinopyrixene has high Mg and Cr but low Ca and Fe, and olivine shows high Mg content.
出处
《矿床地质》
CAS
CSCD
北大核心
1991年第3期255-264,共10页
Mineral Deposits
