Abstract
Experiments were conducted to assess Br/Cl fractionation during phase separation of seawater at 400°C and 250 to 275 bars. These conditions are applicable to the 9-10°N EPR system where low Cl concentrations and low Br/Cl ratios in vent fluids have been attributed to phase separation of seawater at conditions below the critical point of seawater (4008°C, 300 bars). The level of Br/Cl fractionation observed in experiments is well below that needed to account for Br/Cl systematics at EPR 9-10°N. Based on our experimental results, we propose an alternative model involving dissolution and precipitation of halite to account for the anomalous Br/Cl data at 9-10°N. Halite can be predicted to form at pressure and temperature conditions prevailing during eruption of magma at mid-ocean ridges. Subsequent changes in physical conditions, however, would induce halite to dissolve, and thus, decrease Br/Cl ratios of vent fluids.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2849-2854 |
| Number of pages | 6 |
| Journal | Geochimica et Cosmochimica Acta |
| Volume | 61 |
| Issue number | 14 |
| DOIs | |
| State | Published - Jul 1997 |
Bibliographical note
Funding Information:Acknowledgments-We are indebted to S. Oosting and K. Von Damm who made their work on Br/Cl of 9-10”N vent fluids available to us prior to publication. K. Von Damm and an anonymous reviewer provided reviews that greatly improved this paper. This work was supported by grants OCE-9116078 and OCE-9529723 from the National Science Foundation.
Copyright:
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