Chemical and isotopic data for rare massive and semimassive sulfide samples cored at Site 1189 (Roman Ruins, PACMANUS) suggest their genetic relationship with sulfide chimneys at the seafloor. Sand collected from the hammer drill after commencement of Hole 1189B indicates that at least the lower section of the cased interval was occupied by material similar to the stockwork zone cored from 31 to ~100 meters below seafloor (mbsf) in this hole, but with increased content of barite, sphalerite, and lead-bearing minerals. Fractional crystallization of ascending hydrothermal fluid involving early precipitation of pyrite may explain vertical mineralogical and chemical zoning within the stockwork conduit and the high base and precious metal contents of Roman Ruins chimneys. A mineralized volcaniclastic unit cored deep in Hole 1189A possibly represents the lateral fringe of the conduit system. Lead isotope ratios in the sulfides differ slightly but significantly from those of fresh lavas from Pual Ridge, implying that at least some of the Pb within the Roman Ruins hydrothermal system derived from a deeper, more radiogenic source than the enclosing altered volcanic rocks.
1Binns, R.A., 2006. Data report: Geochemistry of massive and semimassive sulfides from Site 1189, Ocean Drilling Program Leg 193. 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/206/206.htm>. [Cited YYYY-MM-DD]
2Division of Exploration and Mining, Commonwealth Scientific and Industrial Research Organisation (CSIRO), PO Box 136, North Ryde NSW 1670, Australia. Ray.Binns@csiro.au
3Department of Earth and Marine Sciences, Australian National University, Canberra ACT 0200, Australia.
Initial receipt: 29 September 2003
Acceptance: 14 November 2005
Web publication:
4 May 2006
Ms 193SR-206