Garnets from the Camafuca-Camazambo kimberlite (Angola)

Anais da Academia Brasileira de Ciências

Eugénio A. Correia¹  Fernando A.t.p. Laiginhas¹ 

[1] ,Universidade do Porto Faculdade de Ciências Departamento de GeologiaPorto,Portugal

关键词: kimberlite;    diamond;    garnet;    lherzolite;    harzburgite;    kimberlito;    diamante;    granada;    lherzolito;    harzburgito;   

DOI  :  10.1590/S0001-37652006000200010

来源: SciELO

【 摘 要 】

This work presents a geochemical study of a set of garnets, selected by their colors, from the Camafuca-Camazambo kimberlite, located on northeast Angola. Mantle-derived garnets were classified according to the scheme proposed by Grütter et al. (2004) and belong to the G1, G4, G9 and G10 groups. Both sub-calcic (G10) and Ca-saturated (G9) garnets, typical, respectively, of harzburgites and lherzolites, were identified. The solubility limit of knorringite molecule in G10D garnets suggests they have crystallized at a minimum pressure of about 40 to 45 kbar (4-4.5 GPa). The occurrence of diamond stability field garnets (G10D) is a clear indicator of the potential of this kimberlite for diamond. The chemistry of the garnets suggests that the source for the kimberlite was a lherzolite that has suffered a partial melting that formed basaltic magma, leaving a harzburgite as a residue.

【 授权许可】

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