Uniformity and diversity in the composition of mineralizing fluids from hydrothermal vents on the southern Juan de Fuca Ridge

Abstract

Oak Ridge National Laboratory, Oak Ridge, Tennessee Abundances of Li, Na, K, Rb, Ca, Sr, Ba, Mn, Fe, Zn, and Si have been determined in fluid samples from seven vents located in three areas on the southern Juan de Fuca Ridge. The hydrothermal component estimated from the Mg contents of the samples ranges from 7% to 76%. Concentrations of Fe and Si, among other elements, in acid-stabilized solutions appear to be generally representative of the parental hydrothermal fluids, but some Zn determinations and most Ba values appear to be too low. Thermodynamic calculations indicate that the acidified samples remain supersaturated with respect to silica, barite, and pyrite; unacidified samples are supersaturated, in addition, with respect to ZnS, FeS, and many silicate phases. Within the constraints of limited sampling there appear to be differences in fluid compositions both within and between the three vent areas. Some uniform differences in the elemental abundances predicted for hydrothermal end-member fluids might be due to inmixing of fresh seawater at depth in the hydrothermal system. The Juan de Fuca hydrothermal fluids contain more Fe but otherwise have relative elemental abundances fairly similar to those in 13øN (East Pacific Rise) fluids, albeit at higher levels. In contrast, fluids from 21øN (East Pacific Rise) and Galapagos have lower K/Rb and much lower Sr and Na abundances; these compositional features probably result from interaction of these fluids with a different mineral assemblage, possibly more mature greenstone. Some K, Rb, Sr, Ba, rare-earth, H20 and CO 2 data bearing on their alteration, modification by plagioclase, and possible source materials, Earth Planet. Sci. Lett., 7, 293-299, 1969.

Neutron-induced prompt gamma activation analysis (PGAA) of metals and non-metals in ocean floor geothermal vent-generated samples

“…Sample 917-R4 contained little silicon, no measurable aluminum, and was mainly composed of copper, nickel and zinc sulfides not found in the other samples. These analyses are consistent with the overall mineralogical analyses of other vent samples that were collected from the two geothermal fields that were previously reported [5][6][7][8][9][10][11][12][13][14][15] .…”

“…We analyzed three samples retrieved from the Juan de Fuca Ridge and the East Pacific Rise ocean floor geothermal vents by the research exploration vessel Alvin. [4][5][6][7][8][9][10][11][12][13][14][15] These samples are representative of the types of material retrieved in dives of the Alvin and thus give an excellent demonstration of complete, simultaneous, nondestructive, multi-element analysis with PGAA. The samples also provide an opportunity to look at a wide array of trace elements that may exhibit varying degrees of complexity in their chemistry.…”

Hydrothermal Manganese Deposits from the Tonga-Kermadec Ridge and Lau Basin Region, Southwest Pacific

“…Hydrothermal uids venting on the Valu Fa Ridge were found by Fouquet and others (1993) to have Li concentrations of up to 26 times those characteristic of seawater. Lithium concentrations of up to 70 times those in seawater are reported to occur in vent waters on the East Paci c Rise (Michard et al, 1984;von Damm et al, 1985;von Damm and Bischoff, 1987;Philpotts, Aruscavage and von Damm, 1987). Partition geochemistry shows that Li is virtually exclusive to the acetic acid soluble phase of the hydrothermal Mn deposits.…”

The potential for abiotic organic synthesis and biosynthesis at seafloor hydrothermal systems

“…(2003); Al 3+ , Ba 2+ and Pb 2+ from Juan de Fuca Ridge S. Cleft Segment, used in the absence of readily available data for Endeavour, are from Hinkley & Tatsumoto (1987), Trefrey et al. (1994), Philpotts et al. (1987), Von Damm & Bischoff (1987) and Evans et al.…”

“…Guaymas data from Von Damm et al (1985b and Campbell et al (1988b), and from compilation by Gamo (1995) where original sources are: Piepgras & Wasserburg (1985), Lupton (1983), Campbell et al (1988b), Welhan & Lupton (1987) and Gieskes et al (1988). Endeavour vent fluid from Lilley et al (1993) and Butterfield et al (1994) in Gamo (1995) and Seewald et al (2003); Al 3+ , Ba 2+ and Pb 2+ from Juan de Fuca Ridge S. Cleft Segment, used in the absence of readily available data for Endeavour, are from Hinkley & Tatsumoto (1987), Trefrey et al (1994), Philpotts et al (1987), Von Damm & Bischoff (1987) and Evans et al (1988). Lau Basin vent fluid composition from Fouquet et al (1991aFouquet et al ( ,b, 1993, and Charlou et al (1991); methane, P CO 2 , H 2 (aq), P H 2 S from maximum values presented in Tivey (2007) for back-arc basins; Al 3+ from White Lady vent in north Fiji back-arc basin (Ishibashi et al 1994a,b).…”