Gas Hydrates
Day 7: Intercontinental explorers August 28, 2011
Location: Noyo Canyon Today we surveyed a part of the San Andreas Fault that dips off the continental shelf into Noyo Canyon, off the coast of Fort Bragg. Because our dive sites were considerably shallow (~400 m water depth), we were able to dive three times in the head of Noyo Canyon today. We were busy bees! Throughout the day we were continuously processing numerous push cores, vibracores, and water samples collected from the ROV.  ROV Doc Ricketts takes a push core along a transect across what we believed to be the San Andreas Fault. Throughout all our dives in Noyo Canyon there was an abundance of beautiful animals. Everyone was wishing Lonny Lundsten was on board to identify all the cool species.
As we followed what we believed to be a trace of the San Andreas Fault, we found this beautiful “oasis” of Metridium sea anemones.
We are very interested in Noyo Canyon because the San Andres Fault crosses the canyon, and it was likely to have a drape of accumulated sediment on it. Throughout our dives, we followed the trace of what we thought would be the fault using low-resolution multibeam maps. Once again, poor weather farther north forced us to dive without our high-resolution multibeam maps. Throughout our dives, we kept going from the North American to the Pacific plate, multiple times; we had quite the day of intercontinental travel! On our second dive, we were in a trough that was parallel to the San Andreas Fault, and the structure of the trough was consistent with an outcrop of a fault. There was no fill in the Noyo Canyon and again, like Delgada Canyon, it was much different than the canyons we’ve seen previously. 
Andreia Afonso pilots the ROV Doc Ricketts as her copilot collects a push core. The intense concentration she maintained while piloting the ROV was replaced by a permanent grin shortly after the ROV was recovered.
Toward the end of the day, one of our collaborators, Andreia Afonso, got the opportunity to fly the ROV Doc Ricketts. Andreia is an ROV pilot with Task Group for Maritime Affairs, Portugal, and jumped at the opportunity to fly the ROV Doc Ricketts. Our ROV is fully hydraulic and bigger in size than the ROVs she is used to flying, so it was a great experience for her. Read about her exciting experience below. — Eve Lundsten and Krystle Anderson Pilot Exchange It was scary at first, but then I felt more comfortable as I became familiar with the movements of the ROV. The setup of my ROV is similar to the setup of the Doc Ricketts in terms of the way you command the movements of the ROV. It wasn’t easy operating the Doc Ricketts at first because we were in a canyon with very strong currents. The currents made it difficult to keep the heading and altitude of the ROV stable. The pilots were so helpful, understanding, and very patient with me, making this experience easy and rewarding. Because there was such a strong current the pilots were continuously showing me the best heading in order to keep a good visual of my surroundings. It felt like I was only operating the ROV for less than five minutes; because it was so exhilarating, I didn’t feel the time passing, and it wasn’t until dinner time that Krystle told me I was flying it for almost an hour! I am so excited to go home to Portugal and tell my co-workers about my experience. They will be so jealous! — Andreia Afonso
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Equipment
 R/V Western FlyerThe R/V Western Flyer is a small water-plane area twin hull (SWATH) oceanographic research vessel measuring 35.6 meters long and 16.2 meters wide. It was designed and constructed for MBARI to serve as the support vessel for ROV operations. Her missions include the Monterey Bay as well as extended cruises to Hawaii, Gulf of California and the Pacific Northwest.
ROV Doc Ricketts is MBARI's next generation ROV. The system breaks new ground in providing an integrated unmanned submersible research platform, with many powerful features providing efficient, reliable and precise sampling and data collection in a wide range of missions.
R/V Zephyr is the primary support vessel for MBARI's autonomous underwater vehicle (AUV) program. This 26-meter vessel is also used to maintain environmental moorings, collect time-series data along the California Current, and support scuba divers as they study near-shore habitats.
The MBARI Mapping AUV is a torpedo-shaped vehicle equipped with four mapping sonars that operate simultaneously during a mission. The multibeam sonar produces high-resolution bathymetry (analogous to topography on land), the sidescan sonars produce imagery based on the intensity of the sound energy's reflections, and the subbottom profiler penetrates sediments on the seafloor, allowing the detection of layers within the sediments, faults, and depth to the basement rock.
A push core looks like a clear plastic tube with a rubber handle on one end. Just as its name implies, the push core is pushed down into loose sediment using the ROV's manipulator arm. As the sediment fills up the core, water exits out the top through one-way valves. When the core is pulled up again, these valves close, which (most of the time) keeps the sediment from sliding out of the core tube. When we bring these cores back to the surface, we typically look for living animals and organic material in the sediments.
Niskin bottles are used to collect water samples as well as the tiny bacteria and plankton in the water. The caps at both ends are open until the bottles are tripped, when the caps snap closed.
Held by the ROV's manipulator, the wire on the right is placed into the fluid emitted from a hydrothermal vent to record the temperature.
The box fits in a partition in the sample drawer. It is shown open, with an animal being placed into it by the ROV's manipulator. When the lid is closed, the box will hold water to protect the animals inside.
Vibracoring is a common technique used to obtain samples from water-saturated sediment. These corers work by attaching a motor that induces high frequency vibrations in the core liner that in turn liquefies the sediment directly around the core cutter, enabling it to pass through the sediment with little resistance.
A CTD rosette is a cylindrical frame holding a group of plastic water-sampling tubes. Attached to this frame are instruments for measuring water temperature and conductivity (salinity) at various depths. Also attached to the rosette are instruments for measuring parameters such as chlorophyll, nutrients, and particulate matter in the water. As the frame is lowered over the side of a ship, water samples are taken automatically at various depths. Then the frame is raised to the surface again. Crew
R/V Western Flyer
ROV Doc Ricketts
Research Team
Charlie Paull has been a marine geologist and geochemical stratigrapher at MBARI since January 1999. The central theme of Charlie's work involves investigating the fluxes of fluids and gases through continental margins. Assessing the global distribution of gas hydrate and interstitial gas is a continuing interest as well as the development of new techniques to detect the presence of gas hydrate in marine sediments. Charlie's other ongoing work is focused on the geology associated with seafloor seepage sites, including investigating the deposits associated with chemosynthetic communities, determining the processes that occur at the methane-sulfate boundary, and understanding the origin of pockmarks and other potential seafloor fluid venting sites.
During expeditions, Bill Ussler is primarily responsible for the operation of the custom-built, portable chemistry lab van which contains a complete analytical laboratory for the analysis of the fluids and gases contained in marine sediments. Along with colleague Charlie Paull, Bill studies how methane (natural gas) forms and moves within seafloor sediments.
Eve Lundsten works with Charlie Paull in the Continental Margins Lab. Eve's background is in hydrology but she uses her mapping skills, and some of her technical skills to help Charlie Paull understand the processes that are creating the features we see on the sea floor. One of her main responsibilities on this expedition will be running the GIS system. We use Arc GIS and our high resolution, AUV collected bathymetric maps to help direct our research to the precise location of interest on the sea floor. Eve will also help out with processing and cataloguing sediment samples and vibracores. Eve is very excited to participate in this cruise and is looking forward to many exciting discoveries.
Roberto is a geochemist by training, and his interests lie at the intersection of marine geology and sediment and water chemistry. On this expedition, Roberto will be responsible for collection and analytical measurements of pore water chemistry on samples taken from sediment cores, and will participate in the collection and analysis of methane from gas vents on the seafloor.
Krystle Anderson is a research assistant working for Charlie Paull in the Continental Margins Lab. Krystle's background is primarily in the acquisition and processing of seafloor mapping data. She came from CSUMB Seafloor Mapping Lab where she obtained her data processing and GIS skills. Krystle spends a majority of her time processing and creating high-resolution maps of multibeam data collected from the mapping AUV. The high-resolution maps Krystle helps create will then be used to aid navigation for the ROV to explore particular areas of interest. On this expedition Krystle will assist with running the GIS system, processing and cataloguing sediment samples and vibracores. This is Krystle's first research expedition with MBARI and she is very excited to be involved in this deep sea excursion.
Philip's specialist interests are in active margin plate boundary processes, including submarine neotectonics, sedimentary basins and sequences, and geohazards. He has undertaken research on subduction, thrust, strike-slip, and rift tectonic systems, sequence stratigraphy and sedimentation processes, submarine landslides, canyon systems, and fluid seepage. Recent initiatives have included the development of on-fault submarine paleoseismic techniques, earthquake source characterisation for national seismic hazard assessment, fluid seepage along the Hikurangi subduction margin, slip rate assessment on the offshore Alpine fault, and submarine canyon development in central and eastern New Zealand. Since the devastating February 2011 earthquakes in Christchurch City, he has been leading seismic reflection studies of active faulting as part of an urgent earthquake risk and recovery work program.
Mary is a micropaleontologist/ biologist with the USGS Pacific Coastal and Marine Science Center. Her interests focus on using microbiota (primarily foraminifera but also pollen) in climate, geohazards, sediment transport, and paleotsunami investigations, as well as in biomonitoring marine pollution sites and for AMS C-14 chronostratigraphy.
Brian Edwards, a sedimentologist with the USGS Pacific Coastal and Marine Science Center, has more than 30 years of sea-going experience on 60-plus coring and geophysical cruises along the west coast of the United States and in high-latitude environments (the Ross Sea [Antarctica], the North Pacific Ocean, the Bering Sea, and the Arctic Ocean). Brian specializes in sedimentary processes and stratigraphy, integrating insights gleaned from seafloor rock and sediment samples with information from remote-mapping products, such as close-up photographs of the seafloor, high-resolution bathymetric maps, and seismic-reflection profiles. His recent studies have focused on how sediment moves from the land to the deep sea, processes controlling submarine landslides, saltwater intrusion into coastal aquifer systems, marine pollution, seafloor habitats, and the Cenozoic history of the Arctic Ocean.
Andreia Afonso has a degree in Marine Sciences from the Lusofona University where she has specialized in the field of Physical Oceanography. Since 2008, Andreia has been working within the former EMEPC (Task Group for the Extension of the Continental Shelf), now called EMAM (Task Group for the Maritime Affairs), where she received ROV pilot and engineer training and has integrated the 6000m rated ROV LUSO technical team. She has participated in five multidisciplinary missions, dominantly in the scope of the Continental Shelf Extension Project involving deep sea research. Andreia is very interested and motivated by the conceptualization, development and implementation of new sea technologies and tools. Apart from EMAM's ROV Team related tasks, she is now project coordinator at EMAM for the development of a modular buoy as a ground for the development of a near shore marine environmental monitoring observatory.
Saulwood Lin is interested in diagenesis in sediments. He has been working on biogeochemical processes associated with gas hydrate and chemical weathering of small river drainage basins. In one ROV cruise he participated, he found a unique cold seep environment in the passive margin off Taiwan. To better understand gas seeps and chemosynthesis community, he joins the MBARI cruise for the purposes of learning ROV instrumentations, sampling and operation of ROV and AUV to facilitate Taiwan's gas hydrate research. |
