Mixing Zephyr Program
Dive 2996

Port Observer: Lilley
Starboard Observer: Kelley
Pilot: Williams
Date: 9/16/95

Summary

Dive Goals: The goals of this dive included completing the recovery of a camera and temperature probe from Milli-Q, and the recovery of temperature probes from Puffer, Cannaport, and Grotto, as well as water sampling at the vent sites.

Dive Summary: We landed eastward of the main fissure between Dudley and S&M at ~4995, 6056, then drove west to the fissure, which we followed south down to Milli-Q. Only at the very beginning of the dive did we have consistent navigation e.g. only to Milli-Q. The dive was successful in recovery of the temperature probes and camera, as well as sampling vent fluids at 3 of the 4 sites. Only at Milli-Q was the probe still in the vent structure: at all other sites the probes had either fallen out of the vents due to tip destruction, vent collapse, or to movement by animals. Upon bringing the probes and camera to the surface all probes had suffered tip destruction, with only 2 of the 16 thermocouple tips preserved, as well as pitting to both the camera and probe pressure housings. At Milli-Q the camera was laying on it’s side previous to recovery. The camera and probe site was not clearly marked, so a triangular marker AZ was deployed at the site and water samples (Gas tight #6 and Major 10) were taken at the vent near marker AZ. Temperatures measured at this vent with the ALVIN temperature probe include 361.2°C, 361.6°C, and 361°C. We then moved upslope ~ 1 m and 4-5 m to the NW (?) to Marker A4 and sampled bottles gas tight #2, manifold port outer major, and gas tight port. Temperatures at A4 were 365.6°C, 365.9°C, and 365°C. Milli-Q was occupied from 11:58 to 13:31. We then traversed over Cannaport and moved on to Puffer. At Puffer, after recovery of the probe, water samples were taken that included port inner major and starboard gas tight bottles. The vent from which the probe was taken was no longer venting, so the samples were taken from upslope of the probe deployment site. Initial insertion of the temperature probe at this vent was unsuccessful as the vent material was highly friable and collapsed upon probe insertion. Subsequently a new vent was sampled that had an orifice ~15 cm in width and that was vigorously venting, exhibiting highly variable and intense “puffing.” The temperature first measured at this vent was 375.6°C, however, the probe was removed due to shifting of the sub and a second temperature of 367°C was measured. At Cannaport, starboard inner and outer majors were sampled. Temperatures measured with the manifold during sampling include 344.7°C and 344.8°C. Upon leaving Cannaport we circled the northwest “arm” of Grotto, spotting old marker W. We then headed southeast at 130° to Marker K, and recovered the temperature probe, which was no longer in the active vent.