Mixing Zephyr Program
Dive 2998

Port Observer: Delaney
Starboard Observer: Sarrazin
Pilot: Heintz
Date: 9/18/95

Summary

Dive Goals: The goals of this dive involved recovery of a camera from Grotto, water sampling at Dudley, S&M, Puffer, and Salut, exploring south of Salut to find a new vent field and Mesotech surveying between the different vent structures.

Dive Summary: We landed eastward of Grotto at ~ 5150, 6050, then drove west to Grotto. The camera at Grotto was sitting beside marker BA and the recovery was successful. A sulfide sample was taken in near Grotto. We completed a Mesotech survey at 30m above bottom from Grotto to S&M. At S&M, video transects of the chimney were taken at 3 different headings. We sampled a black smoker located on the east face of S&M, over the fissure. Gas tight and major #6 water samples were taken with a temperature of 368°C. We did another Mesotech while heading south to Salut. Navigation was good during almost the entire dive. At Salut, we located a flange with an underlying pool and took two majors (port side outer and port inner) and one gas tight sample under the flange. The maximum temperature recorded was 350°C for the first sampling, and then 200-140°C for the second one. Breaking of the flange's lip by the manipulator arm may explain the decrease in temperature. A sulfide from that flange, covered by biology was sampled. From Salut we headed south, looking for a new vent site that was indicated by temperature anomalies recorded by Lilley's research group. On our way, we sampled a piece of sulfide coming from an old dead sulfide. At around 15:00 we discovered an extensive area of diffuse venting that was covered by the usual tube worm community. The tube worms were healthy, some of them reaching more than 1 meter long. A biological sample was taken and marker AV was deployed on the sampling site. Then we moved south-west of that field to do some water sampling. One gas tight (#5) and three majors (starboard side major outer and inner + hand held major (#10) were taken over a shimmering area (T°C= 12.7) covered mostly by bacterial mats, snails, and limpits. Marker 1H was deployed on this sampling site. Thereafter, we tried an unsuccessful temperature reading with the manifold. The new diffuse flow vent site's name was gently proposed by John as: Quebec, with approximate coordinates of the new field at ~ 4806-4843 and 5508-5553.