Behavior of rare earth elements in coexisting manganese macronodules, micronodules, and sediments from the central Indian Basin

Abstract

Associated manganese macronodules, micronodules, and sediments from the Central Indian Basin (CIB) were analyzed for major, trace, and rare earth elements (REE) to understand REE carrier phases and their fractionation pattern among three depositional phases. The average REE abundance is higher in macronodules (1,164 ppm) than in the micronodules (650 ppm) and sediments (210 ppm). The similar fractionation pattern (MREE - HREE - LREE) in the three coexisting phases suggests that fractionation is independent of REE content, sediment type, and REE carrier phases. This could be due to retention of bottom water REE pattern. Macro-and micronodules from the same sedimentary environment appear to have similar distribution trends of transition metals, Ce anomalies, fractionation pattern, and REE partition coefficient, suggesting that a similar process controls the enrichment of these elements