chemistry is suggested. New sampling methods have been 

 formulated, and the instrumentation required to implement them 

 tested. A rationale for submersible-based vent fluid sampling 

 within the overall context of the VENTS Program has been 

 explained. Vent fluids occupy an important part of the elemental 

 concentration, temperature, spatial, and temporal scales (Fig. 9) 

 over which hydrothermal effects investigations are made. The 

 integration of the results obtained from throughout these scales 

 is required to test the VENTS hypothesis. 



ACKNOWLEDGMENTS 



We thank the officers and crews of R/V Pandora II AND R/V 

 Atlantis II, and the Pisces IV and Alvin pilots for valuable 

 guidance at sea. Marvin Lilley, Barrie Walden, Patrick McLain and 

 Dennis Holzer contributed significantly to the design, 

 fabrication, and testing of the SIS^. Ken Johnson and Susie 

 Kalhorn assisted with the design and fabrication of the ISCA. 

 Kevin Roe performed the determinations of Mn and Fe in the vent 

 fluids. Karen Thornberry assisted with the ^He determinations. 



LITERATURE CITED 



ASHES Expedition. 1986. PISCES submersible exploration of a 



high-temperature vent field in the caldera of Axial Volcano, 

 Juan de Fuca Ridge. EOS , Vol. 67, No. 44, p. 1027. 



Baker, E. T., and G. J. Massoth. 1986. Hydrothermal plume 

 measurements: a regional perspective. Science , Vol. 234, 

 pp. 980-982. 



Baker, E. T., and G. J. Massoth. 1987. Characteristics of 



hydrothermal plumes from two vent fields on the Juan de Fuca 

 Ridge, northeast Pacific Ocean. Earth Planet. Sci. Lett. , 

 Vol. 85, pp. 59-73. 



Baker, E. T., G. J. Massoth, and R. A. Feely. 1987a. Cataclysmic 

 hydrothermal venting on the Juan de Fuca Ridge. Nature , Vol. 

 329, No. 6135, pp. 149-151. 



Baker, E. T., G. J. Massoth, R. W. Collier, J. H. Trefrey, 



D. Kadko, T. A. Nelson, P. A. Rona, and J. E. Lupton. 1987b. 

 Evidence for high-temperature hydrothermal venting on the 

 Gorda Ridge, northeast Pacific Ocean. Deep Sea Res. , Vol. 34, 

 No. 8, pp. 1461-1476. 



Baker, E. T., R. A. Feely, and G. J. Massoth. 1987c. 



Hydrographic and chemical survey of hydrothermal plumes of the 

 Middle Valley vent field, Juan de Fuca Ridge. EOS , Vol. 68, 

 No. 44, p. 1325. 



55 



