7. Data Report: Chemical and Isotopic (S, Sr) Composition of Anhydrite from ODP Leg 193, PACMANUS Hydrothermal System, Manus Basin, Papua New Guinea1

Wolfgang Bach,2 Stephen Roberts,3 and Ray A. Binns4


Sr and S isotope data as well as trace element data for anhydrite samples from Sites 1188 and 1189 in the PACMANUS hydrothermal area are presented here. 87Sr/86Sr ratios range from 0.7050 to 0.7086, suggesting that the anhydrites precipitated from fluids that were variably influenced by entrained seawater (0%–89%). 34S values range between 18.1 and 22.5, indicating the main source of sulfate is seawater that may be affected to small extents by sulfide oxidation or magmatic sulfate input (34S < 21) and minor sulfate reduction (34S > 21). Rare earth element (REE) concentrations are highly variable, particularly at Site 1188. Chondrite-normalized REE pattern shapes comprise light REE enriched, light REE depleted, mid-REE enriched, and variable positive and negative Eu anomalies. Significant correlations between trace element and isotopic compositions are lacking. Anhydrite from Site 1188, a site of diffuse venting, has systematically lower 34S and higher Sr contents and somewhat lower average 87Sr/86Sr than anhydrite from Site 1189. This is possibly a consequence of the different fluid flow regime with diffuse flow at Site 1188 and focused flow at Site 1189.

1Bach, W., Roberts, S., and Binns, R.A., 2005. Data report: Chemical and isotopic (S, Sr) composition of anhydrite from ODP Leg 193, PACMANUS Hydrothermal System, Manus Basin, Papua New Guinea. In Barriga, F.J.A.S., Binns, R.A., Miller, D.J., and Herzig, P.M. (Eds.), Proc. ODP, Sci. Results, 193 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/193_SR/214/214.htm>. [Cited YYYY-MM-DD]

2Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole MA 02543, USA. wbach@whoi.edu

3Southampton Oceanography Centre, Empress Dock, University of Southampton SO14 3ZH, United Kingdom.

4CSIRO Exploration and Mining, PO Box 136, North Ryde NSW 2113, Australia.

Initial receipt: 12 March 2004
Acceptance: 13 October 2004
Web publication: 26 January 2005
Ms 193SR-214