Determination of Trace Element Compositions of Altered Minerals in Fenitization Veins by Inductively Coupled Plasma-Mass Spectrometry

Abstract

BACKGROUND In recent years, whole-rock inductively coupled plasma-mass spectrometry (ICP-MS) trace and in situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) trace element analyses have been increasingly more widely used in the field of earth sciences. Fenitization is a common type of alteration in carbonate-type rare earth deposits, but the relationship between the trace element characteristics of altered minerals and rare earth mineralization is not clear. OBJECTIVES To better understand the relationship between fenitization and REE mineralization in the Maoniuping deposit as well as to provide references for prospecting carbonate-related (including alkaline rock) REE deposits. METHODS Trace elements for aegirine-augite and arfvedsonite in different stages of fenitization veins (ore-bearing or barren rocks) from the Maoniuping deposit, Dagudao area were analyzed by ICP-MS and LA-ICP-MS. RESULTS In situ trace elements of aegirine-augite in different stages of fenitization veins showed that La/Nd (0.19-0.23), LREE/HREE (6.58-7.79), Ce/Nd (0.95-1.11), (La)N/(Yb)N (2.07-2.33) values of aegirine-augite in ore-bearing veins were higher than those of barren veins. CONCLUSIONS Compared with whole rock trace elements, high contents of La, Ce, LREE, ΣREE in mineral veins, strong differentiation of light and heavy rare earths may represent fenitization-related fluid with high rare earth flux. The occurrence of fenitization veins and the whole-rock trace and in situ trace geochemical indicators of aegirine-augite in veins may provide references for the prospecting and exploration of carbonate-type rare earth deposits.

Keywords

• maoniuping
• fenitization
• alteration
• trace elements
• aegirine-augite
• arfvedsonite