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Nilsson Farley, Kristen (1994): Geochemistry and oxidation state of Lau Basin basalts [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.793498, Supplement to: Nilsson Farley, K (1994): Oxidation state and sulfur concentrations in Lau Basin Basalts. In: Hawkins, J; Parson, L; Allan, J; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 135, 603-613, https://doi.org/10.2973/odp.proc.sr.135.145.1994

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Abstract:
The backarc glasses recovered during Ocean Drilling Program Leg 135 are unique among submarine tholeiitic glasses with respect to their oxygen fugacity and sulfur concentrations. Unlike mid-ocean-ridge basalt glasses, fO2 in these samples (inferred from ratios Fe3+/Fe2+) is high and variable, and S variations (90-1140 ppm) are not coupled with FeO concentration. Strong correlations occur between the alkali and alkaline-earth elements and both fO2 (positive correlations) and S concentrations (negative correlations). Correlations between fO2 and various trace elements are strongest for those elements with a known affinity for hydrous fluids (perhaps produced during slab dehydration), suggesting the presence of a hydrous fluid with high fO2 and high alkali and alkaline earth element concentrations in the Lau Basin mantle.
Concentrations of S and fO2 are strongly correlated; high fO2 samples are characterized by low S in addition to high alkali and alkaline earth element concentrations. The negative correlations between S and these trace elements are not consistent with incompatible behavior of S during crystallization. Mass balance considerations indicate that the S concentrations cannot result simply from mixing between low-S and high-S sources. Furthermore, there is no relationship between S and other trace elements or isotope ratios that might indicate that the S variations reflect mixing processes. The S variations more likely reflect the fact that when silicate coexists with an S-rich vapor phase the solubility of S in the silicate melt is a function of fO2 and is at a minimum at the fO2 conditions recorded by these glasses. The absence of Fe-sulfides and the high and variable vesicle contents are consistent with the idea that S concentrations reflect silicate-vapor equilibria rather than silicate-sulfide equilibria (as in MORB). The low S contents of some samples, therefore, reflect the high fO2 of the supra-subduction zone environment rather than a low-S source component.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: -19.484208 * Median Longitude: -177.182242 * South-bound Latitude: -20.709000 * West-bound Longitude: -177.862000 * North-bound Latitude: -18.501000 * East-bound Longitude: -176.500000
Date/Time Start: 1990-12-21T20:35:00 * Date/Time End: 1991-01-24T00:40:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
2 datasets

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Datasets listed in this publication series

  1. Nilsson Farley, K (1994): (Table 3) Oxygen fugacity of glasses from ODP Leg 135 basalt samples. https://doi.org/10.1594/PANGAEA.793495
  2. Nilsson Farley, K (2012): (Table 2) Major element composition of glasses from ODP Leg 135 basalt samples. https://doi.org/10.1594/PANGAEA.793494