Sulfate minerals control dissolved rare earth element flux and Nd isotope signature of buoyant hydrothermal plume (EMSO-Azores, 37°N Mid-Atlantic Ridge)

Abstract

While hydrothermal vents are now thought to be a major source of dissolved iron to the oceans, they have always been considered to be a sink for the dissolved rare-earth elements (DREEs). However, true dissolved REE observations in hydrothermal plumes are still lacking. Here we report for the first time the DREE concentrations and neodymium isotopic compositions (DεNd) of buoyant hydrothermal fluids at Lucky Strike (Mid-Atlantic Ridge). We find that 27 to 62% of total hydrothermal DREEs are rapidly scavenged by anhydrite precipitation at the onset of buoyant plume formation. After this initial loss, all DREEs behave quasi-conservatively within the buoyant plume. Dissolved phase εNd (DεNd) in the evolving plume are identical to black smoker DεNd of +9.0 and contrast radically with DεNd of the local deep water mass at −12.0. Plume DεNd as low as +6.6 may be reconciled by dissolution of newly formed barite in the local environment and carrying seawater DεNd signature. We find, based on the first plume DREE observations, that hydrothermal plumes are in fact a source of DREE to the North Atlantic Deep Water. Precipitation/dissolution processes of hydrothermally-derived minerals, i.e. sulfates in the buoyant plume and Fe oxy-hydroxide in the non-buoyant plume, will likely affect the fate of other Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.trace metals and their isotopic composition.

Spatial Variations in Vent Chemistry at the Lucky Strike Hydrothermal Field, Mid‐Atlantic Ridge (37°N): Updates for Subseafloor Flow Geometry From the Newly Discovered Capelinhos Vent

“…The long known LSHF (Charlou et al, 2000, Chavagnac et al, 2018Pester et al, 2012;Von Damm et al, 1998, Figure 1) comprises 20-30 sites with high-temperature black smokers (T = 200-340°C) and low-temperature diffuse venting (total area about 1,800 m 2 , Barreyre et al, 2012). These sites are all clustered around a fossil lava lake (300 m in diameter; Fouquet et al, 1995) framed by two ancient volcanic cones, and one of which has been truncated by N010-N030°faults and fissures (Ondréas et al, 2009, Figure 1).…”

Seawater‐Particle Interactions of Rare Earth Elements and Neodymium Isotopes in the Deep Central Arctic Ocean

“…(2018), Chavagnac et al. (2018), and Jeandel (1993). However, no shift in the dNd isotope composition toward more radiogenic values is observed at stations 68 and 70 relative to over‐ and underlying samples nor adjacent stations.…”

“…Hydrothermal fluids are strongly enriched in [REE] in comparison to seawater, with a strong positive Eu‐anomaly (Mitra et al., 1994). Upon mixing with seawater, Fe‐Mn‐oxyhydroxides precipitate and scavenge REEs, not only effectively removing the vent fluid REEs, but also leading to a depletion of seawater REEs in the hydrothermal plume (e.g., Chavagnac et al., 2018; German et al., 1990; Klinkhammer et al., 1983; Mitra et al., 1994; Stichel et al., 2018).…”

Prokaryote Communities at Active Chimney andIn SituColonization Devices After a Magmatic Degassing Event (37°N MAR, EMSO‐Azores Deep‐Sea Observatory)

“…Since its discovery in 1992, LSHF has been well characterized with respect to fluid chemistry (Charlou et al, 2000;Chavagnac, Saleban, et al, 2018;Langmuir et al, 1997;Pester et al, 2012;Von Damm et al, 1998), geological settings (Barreyre et al, 2012;Escartín et al, 2008;Escartín et al, 2015;Fouquet et al, 1994;Humphris et al, 2002;Ondréas et al, 2009;Singh et al, 2006), macrobiological, and microbiological communities (Crépeau et al, 2011;Cuvelier et al, 2009;De Busserolles et al, 2009;Desbruyères et al, 2001;Flores et al, 2011;Lee Van Dover et al, 1996;. Since its discovery in 1992, LSHF has been well characterized with respect to fluid chemistry (Charlou et al, 2000;Chavagnac, Saleban, et al, 2018;Langmuir et al, 1997;Pester et al, 2012;Von Damm et al, 1998), geological settings (Barreyre et al, 2012;Escartín et al, 2008;Escartín et al, 2015;Fouquet et al, 1994;Humphris et al, 2002;Ondréas et al, 2009;Singh et al, 2006), macrobiological, and microbiological communities (Crépeau et al, 2011;Cuvelier et al, 2009;De Busserolles et al, 2009;Desbruyères et al, 2001;Flores et al, 2011;Lee Van Dover et al, 1996;.…”

“…The Lucky Strike hydrothermal field (LSHF-MAR, N37°17′/W32°17′) offers an excellent opportunity to examine the links between microbial biosphere development and hydrothermal fluid flux in that context. Since its discovery in 1992, LSHF has been well characterized with respect to fluid chemistry (Charlou et al, 2000;Chavagnac, Saleban, et al, 2018;Langmuir et al, 1997;Pester et al, 2012;Von Damm et al, 1998), geological settings (Barreyre et al, 2012;Escartín et al, 2008;Escartín et al, 2015;Fouquet et al, 1994;Humphris et al, 2002;Ondréas et al, 2009;Singh et al, 2006), macrobiological, and microbiological communities (Crépeau et al, 2011;Cuvelier et al, 2009;De Busserolles et al, 2009;Desbruyères et al, 2001;Flores et al, 2011;Lee Van Dover et al, 1996;. Moreover, since 2010, the deep-sea observatory-EMSO-Azores Sarradin, Blandin, Escartıń, Cannat, et al, 2010)-has been deployed allowing a continuous geophysical and biological survey, together with annual sampling of hydrothermal fluids, fauna and microbial communities.…”