Geochemistry of REE and yttrium in hydrothermal fluids from the Endeavour segment, Juan de Fuca Ridge

Abstract

Rare earth element and yttrium in hydrothermal fluids sampled from six high temperature vents and two diffuse flow sites on the Endeavour segment, Juan de Fuca Ridge by US-CHINA Joint Deep Dive Cruise in Aug. 2005 were analyzed by ICP-MS after being pre-concentrated by 20-fold. According to the species distributions calculated by GWB, the chondritenormalized REE patterns (REE CN ) of these fluids are characterized by LREE enrichment and positive Eu anomalies, which are mainly controlled by complexing with chloride. The (La/Yb) CN ratio does not correlate significantly with fluoride. Sulfate content are low in most high temperature fluids except in Gremlin vent fluids. Certain amounts of REE are complexed with sulfate that likely originates from oxidation of magmatic SO 2 and/or H 2 S in Gremlin. Sulfates, mostly come from seawater, are also responsible of large percentage of REE complexes in diffuse fluids.It is shown by the character of REY concentrations and the Y/Ho ratios that REE removed by Fe, Mn-oxyhydroxides is negligible in most of high temperature vent fluids. However, the Y/Ho ratios in Gremlin (Y/Ho = 160) and Faulty Towers (Y/Ho = 140) vent fluids are higher than that in other high temperature vent fluids, suggesting REE removal controlled by coprecipitation and scavenging. The negative Ce anomalies in diffuse fluids also result from the scavenging of mineral particles in the oxidizing conditions when mixing with seawater. Compared to ideal mixing fluids calculated by Mg content, two diffuse fluids display LREE-depleted patterns and enhanced positive Eu anomalies. Based on the REE characteristics of anhydrite, the REE distribution patterns of diffuse fluids are probably influenced largely by anhydrite precipitation under the seafloor at diffuse fluids sites. It is interesting to notice that the HREE CN pattern of Mothra vent fluids is similar to sediments but different from the sediment-starved hydrothermal fluids, suggesting they are likely remolded by the sediments in water-rock interaction zone and/or upflow zone nearby Mothra vent field. The provenance and character of these sediments bears further investigation.Keywords: hydrothermal fluids, rare earth element, Juan de Fuca Ridge, species abundance, Europium anomaly (Fouquet et al., 1993).Although the characteristics of REY in MOR systems have been well documented, the factors controlling the patterns and distributions of REY in hydrothermal fluids are still in debate. Klinkhammer et al. (1994a) systematically studied the REE of hydrothermal fluids from eight deep-sea hydrothermal areas and predicted that the REE distribution is dominated by crystochemical exchange with plagioclase phenocrysts. However, laboratory experiments indicated interstitial material and some secondary minerals are the main REE sources in the rock (Bach and Irber, 1998). Furthermore, coprecipitating with metal particles (German et al

Geochemistry of REE, Zr and Hf in a wide range of pH and water composition: The Nevado del Ruiz volcano-hydrothermal system (Colombia)

“…The twin pairs' fractionation in Group 1 is due to the formation of the observed authigenic solid phases (Fe-, Aloxyhydroxides) stable at neutral pH. The preferential removal of Ho and Hf with respect to Y and Zr is attributed to the enhanced scavenging during the co-precipitation onto the surfaces of Fe, Al oxyhydroxides (Bau, 1999;Bau and Dulski, 1999;Bao et al, 2008;Censi et al, 2007;Feng, 2010, Schmidt et al, 2014. However, in Botero Londono water (Group 1b), Y-Ho and Zr-Hf do not significantly fractionate and Ce anomaly is negligible (Fig.…”

“…The REE abundances provide insight into water-rock interaction processes. The REE geochemistry in geothermal fluids is complex and depends on the pH, the stability of solid phases, the concentrations of anionic ligands complexing the REE and adsorption of mineral surfaces (Wood, 1990(Wood, , 2003Lewis et al, 1997Lewis et al, , 1998, and references therein; Gammons et al, 2005;Bao et al, 2008;Peiffer et al, 2011). The concentration of total dissolved REE in near neutral pH waters and in seawater is low and their dissolved species are dominated by carbonate complexes (Byrne, 2002), whereas in acidic waters (pH b 3.6) carbonate and hydroxide can be considered negligible.…”

Hydrothermal activities and seawater acidification in the Late Devonian F-F transition: Evidence from geochemistry of rare earth elements

“…Those REE characteristics are similar with the REE of hydrothermal fluids and associated hydrothermal sediments [32][33][34]. REE of hydrothermal fluids from modern mid-oceanic ridges are characterized by high Eu anomaly value (about 9.29) and obvious fractionation of LREE [33,35].…”

Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)

“…Monazite with positive Eu anomalies has been reported from banded iron formations [44], carbonatites [87], lower crustal rocks [88,89], and in metamorphic rocks as inclusions in plagioclase [90]. Fluids with strongly positive Eu anomalies are characteristic of highly reducing conditions [91][92][93][94], including back arc basin settings like the Llallagua deposit [95].…”