2115 SE O.S.U. Dr.
Newport, OR 97365-5258
Department of Marine Sciences
250 Marine Sciences Building
Athens GA 30602
Di Iorio - 706 542 7020
Di Iorio - daniela @uga.edu
The NeMO seafloor observatory was established in 1997 to conduct time-series measurements of the physical, chemical, and biologic systems at an active submarine volcano. Annual expeditions to Axial Volcano since 1997 have documented important changes following a major eruption in January 1998. Remotely operated vehicles have been used to sample vent fluids, rocks, and biological material, and deploy and recover monitoring instruments on the seafloor. The 2007 program on Atlantis with Jason 2 will continue the time-series measurements and sampling.
A mapping program with the MBARI AUV D. Allan B. was begun in 2006 will continue on NeMO 2007 with the primary goal of finishing a high resolution map of the caldera and the shallow parts of the north and south rift zones.
This cruise will be operated jointly with the NSF-funded program of D. Di Iorio. The first few dives will be at the Endeavour Ridge vent fields to accommodate this program.
Di Iorio
Science Objectives:
The main objective of this research is to measure continuously, for extended periods of time (> months) the along-valley tidally driven horizontal flow, and the buoyantly driven vertical flow and temperature fluctuations of hydrothermal vent fluid from either Hulk or Grotto vents in the Main Endeavour vent field (decision on the black smoker vent is dependent on NEPTUNE Canada integrated studies site). Measurements will be over an extended period of time so that comparisons can be made with independent seismic data collected by NOAA/PMEL. This will be accomplished by deploying an acoustic scintillation system within 50 m of the vent plume.
The primary scientific goals/tasks planned for NeMO 2007 include:
At Endeavour:
1. Recover long-term time-series instruments from one site at Endeavour.
2. Conduct chemical, biological, and geological sampling at Main Endeavour and Mothra hydrothermal fields.
3. AUV mapping in Endeavour Axial Valley (if schedule permits)
4. High-resolution mapping of vent fields at Endeavour.
At Axial:
1. conduct repeat pressure measurements with Jason on seafloor benchmarks, three transects during one ~36 hour dive.
2. Deployment of two seafloor chemical samplers (RAS) on small moorings for un-monitored, pre-programmed time series measurements at Endeavour and Axial.
3. Chemical, biological and microbiological sampling throughout Axial Volcano caldera, CASM, ASHES, and SE (International) vent fields.
4. Recovery of 2 bottom pressure recorders and 4 ocean bottom hydrophones at Axial Volcano and redeployment later during the cruise.
5. Recovery and re-deployment of temperature monitors at seafloor hot spring sites with Jason.
6. CTD/rosette casts at Axial Volcano.
7. Complete high resolution AUV mapping of summit of Axial Volcano
DiIorio
1) Survey appropriate black smoker vent (either Hulk or Grotto) to determine the location of the scintillation transmitter mooring (Tx) and scintillation receiver mooring (Rx). Each will be placed approximately 50 m from the plume aligned perpendicular to the axial valley direction. Sample the plume temperature as a function of height (from the orifice to 25 m above). Video image the plume from the orifice to 25 m above. If a high frequency digital echosounder is available then obtain cross sectional imagery of the plume (see vehicle-related instrumentation section below).
2) Build the acoustic transmitter mooring (Tx) which will be approximately 35 m long with syntactic foam floatation. Deploy it at a drop location near either Hulk or Grotto vents.
3) Locate the Tx mooring (which will have a transponder coded appropriately so that it won't conflict with other beacons in the area) with Jason, using a homer probe. Lift the mooring (which will be <40 kg in water) from the top using the moorings' floating tag line and move it to the location identified in activity 1.
4) Build the Rx mooring with similar specifications as the Tx mooring described in 2) and 3) above. Deploy to a drop location where Jason can get it.
5) Move the Rx mooring to its location identified in activity 1.
| Juan de Fuca Ridge: Endeavour and Axial Segments |
| Vicinities of 48deg00'N;128deg08'W and 46deg00'N; 130deg00'W, respectiviely |
Di Iorio
| Main Eneavour vent field |
| 47deg 56.88 N, 129deg 5.94W |