 Leg 5 Logbook - Submarine Volcanism II
Day 6 — President Jackson Seamounts
September 3, 2009 Latitude 42 degrees 49.84 minutes N Last night a storm was predicted to move across where we were working on the Juan de Fuca Ridge. I think we have to thank Nicky for it (the meteorologist out with us last leg)! We abandoned North Cleft and headed south to safer seas. We dove today at one of the President Jackson Seamounts, and will dive here again tomorrow. The seamounts in this chain erupted one at a time near the Gorda mid-ocean ridge and travel with the Pacific Plate as it slides to the northwest, away from the ridge. So they are progressively younger, from west to east. We dove in 2000 and 2002 with ROV Tiburon at the eastern end of the chain on the two youngest seamounts. The dive today was on the next-to-oldest. It had been dredged in the 1980s by the USGS before GPS navigation allowed them to know precisely from where on the seamount their samples came. Our dive began in the muddy bottom of the deepest caldera, climbed a long talus slope at the base of the caldera wall to a cliff with outcrops of massive lava flows and pillow lavas, and finally a volcaniclastic (broken volcanic rock) unit at the rim. That caldera lies within a larger, older caldera. The floor of that one is also a muddy plain, which we crossed and climbed the caldera wall to the top. Along the way we did bio-transects (Craig and Linda were ecstatic to see mud again) and collected animals and rocks. —Jenny Paduan 
Talus of large and small angular blocks at the base of the caldera wall. Smaller volcanic fragments in the sediment are commonly glass with altered rinds and manganese-oxide crusts. The sediment itself is mostly planktonic foraminifera ooze that settled to the seafloor from the surface water where these microscopic animals live. It is very light and forms dense muddy clouds when disturbed that obscure our view when we sample rocks and animals. 
Almost-columnar jointed, massive flow in the caldera wall. The columns form in thick lava flows that cool slowly and the hexagonal or nearly hexagonal joints serve to cool the flow. Such thick flows cropping out in the caldera walls indicate that this caldera cuts through flows that ponded in a prior caldera. A feather star (crinoid) and smaller brittle stars (ophioroids) cling to the rocks. Deep-sea mud. There is a lot of it on earth. Considering that 70 percent of the earth's surface is ocean and that most of the ocean floor is deep-sea mud, that makes it one of the largest habitats on earth. Lots of things live on top of it, but the real story for me is what is going on underneath. The top 10-20 cm of sediment support lots of very small animals like worms, tiny crustaceans, clams, snails, and foraminifers. In the amount of mud you could fit into a soda can, there could be hundreds of these small critters, and most you can only see with a microscope. Imagine how many there are in the whole ocean! And then there are the bigger roaming animals, like the heart urchin. They live almost exclusively under the mud, so when we see a live one on the surface, it is a nice surprise. 
A heart urchin on the surface of the mud. Red laser dots are 29 centimeters apart for scale. Heart urchins can be very abundant and move around under the mud while feeding. We only saw one, but knew that there are many, many more by looking at the bioturbated mud. Can you tell where they are under the surface? Check out the lighter-colored areas and places where there are mounds in the mud. And a big hello to Mr. Slyder’s second block biology students who are following these logs. —Linda Kuhnz 
Bioturbation has brought lighter-colored mud to the surface. The darker patches are gravel that contains volcanic glass, so the hard-rock geologists are happy too. Today, I write about sea stars that are particularly near and dear to my heart: the brisingids. We encountered a spectacular individual today with its arms outstretched to nearly 60 centimeters (two feet) across! Until recently, only one Atlantic brisingid had been observed to have this incredible arm span. What are brisingids? Brisingids are true sea stars and are distant relatives within the group that includes the common intertidal sea stars, such as the ochre star (Pisaster ochraceus). Brisingids have become adapted to life in the deep sea: they are filter feeders. They capture food, often crustaceans, from the current as it flows through long needle-like spines on the arms. These spines, and often other parts of the body, are covered by small claw-like structures called pedicellariae that act as a kind of starfish “Velcro” and close shut when prey collide with them. Food is then moved via the tube feet and arms to the mouth. Brisingids have multiple arms, from six to 18, making them more effective at filter feeding. The skeleton between the disk and the arm is often arranged to keep the arms locked in place while they are extended. Even the name “brisingid” is unusual. The name is derived from a Norse legend which tells of the Queen of the Norse gods, Freya, who was fond of a star-shaped broach called “Brisingamen”, which was stolen by the mischeivious god Loki and thrown into the Ancient Ocean. It is the name of this broach from which the name “brisingid” is derived. All the Latin names of brisingid sea stars are based on Norse gods: Odin, Freya and so on. And on a personal note, my first research papers were on brisingids! Most of the specimens were collected in trawl nets and badly damaged. They are far cry from a brisingid's majesty when alive. So, what do I feel about seeing one that was over 60 cm in diameter? It was a good day. —Chris Mah 
Brisingid star, with 60 centimeter arm span, on a block of lava talus. 
Julio carefully removing an attached animal from a rock sample for
preservation..
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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 ROV Tiburon'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 that volume. The caps at both ends are open until the bottles are tripped, when the caps snap closed.
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.
This device is used to collect volcanic glass fragments from the surface of a flow. It is made of about 450kg of lead and steel and is launched over the stern of the ship on a wire. Fragments of rock that break off of the lava flow on impact are trapped in wax-tipped cones mounted around the crusher. The wax is melted in the lab to liberate the rock particles for analysis.
The benthic toolsled is attached to the bottom of the ROV for our geology dives. Its components are the manipulator arm and the sample drawer. The sample drawer is shown open on deck, full of rocks. Normally it is closed when the vehicle is operating and is opened only when a sample needs to be stowed. Partitions in the drawer help us keep the rocks in order. The rocks often look alike, but the conditions and chemistries of the eruptions are different so it is important that we know where each came from.
This equipment is used to vacuum glass particles and larval animals from cracks and crevices. The carousel of small plastic jars fitted with wire mesh will be mounted in the benthic toolsled. The hose will be held by the ROV's manipulator and a suction will be drawn by the pump.
Canvas bags on a T-handle for collecting gravel or other materials that fall out of a push-core.
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. Research Team
Dave's research interests are nearly all related to the formation and degradation of oceanic volcanoes, particularly Hawaiian volcanoes, mid-ocean ridges, and isolated seamounts. Topics of interest include: compositions of mantle sources for basaltic magmas and conditions of melting; volatile and rare-gas components in basaltic magmas and their degassing history; chronostratigraphic studies of eruption sequence and evolution of lava chemistry during volcano growth; subsidence of ocean volcanoes and its related crustal flexure, plate deformation, and magmatic activity; geologic setting of hydrothermal activity; origin of isolated seamounts; and monitoring of magmatic, tectonic, and hydrothermal activity at submarine and subaerial volcanoes.
Jenny works with Dave Clague in the Submarine Volcanism project. On this expedition, Jenny will be in charge of the GIS work, including use of the recently acquired, high-resolution MBARI Mapping AUV data of our dive sites. She will also stand watches in the ROV control room, help with rock and sediment sample workup and curation once the vehicle is on deck, and coordinate these cruise logs for our group's two legs of the expedition. She is now quite solidly a marine geologist, but her degrees are in biochemistry (Smith College) and biological oceanography (Oregon State University). She is thankful for the opportunities that have led her to study volcanoes, and loves being involved with the research and going to sea. She looks forward to discovering more about how the Earth works.
Brian completed his Ph.D. in igneous geochemistry at Washington University in Saint Louis in 2007 and has since been working in MBARI's Submarine Volcanism Group. Brian applies the principles of isotope geochemistry to young samples of volcanic rocks to gain insight into aspects of magmatism. Much of his postdoctoral work focuses on eruption and petrogenetic timescales of Axial Seamount, the most volcanically active portion of the Juan de Fuca Ridge. His other research interests include geochemistry of the Earth's mantle, magmatic interaction between oceanic spreading centers and hotspots, and exploiting the systematics of rare isotope species to quantify material flux through subduction zones.
Craig has conducted deep-sea research for 11 years and published over 30 papers in the area. Participation in dozens of expeditions has taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig's research focuses on the ecological and evolutionary drivers of marine invertebrate biodiversity and body size. He is the author and editor of Deep-Sea News, a popular deep-sea themed blog and rated as the number one ocean blog on the web, and his popular writing has been featured in Cosmos, Science Illustrated, and Open Lab: The Best Science Writing on the Web.
Linda specializes in the ecology of small animals that live in marine sediments (macrofauna), and larger invertebrates and fishes that live on the seafloor or just above it (megafauna). She conducts habitat characterization studies in benthic (seafloor) ecosystems using underwater video and by collecting deep-sea animals. She hopes to find some new and interesting animals in the unique habitats we are visiting on this cruise.
Angel is a carbonate sedimentologist specialist in non-tropical carbonate sediments. His current research, however, is focused on the tropical realm. He is working on drowned reefs from Hawaii, studying their morphology and structure, sedimentary facies and stratigraphical successions in order to attempt to constraint eustatic sea-level changes, subsidence rates, drowning times, carbonate accretion rates, and paleobathymetry. In this expedition Angel hopes to learn basic skills in marine geology that could help him to better understand the data he works with in his current research.
Julio is a molecular ecologist and evolutionary biologist currently working on the population genetics of various deep-sea invertebrate species in Bob Vrijenhoek's laboratory. Julio is also developing molecular probes capable of detecting a variety of marine invertebrate larvae and other microorganisms from environmental seawater samples as part of the Environmental Sample Processor project.
Chris specializes in the evolution, systematics, and taxonomy of echinoderms, specifically asteroids (starfish or sea stars). His research emphasizes cold-water species, including those living in the deep sea and at high-latitudes (Antarctica and the Arctic). He has identified starfish species for National Geographic, the National Marine Fisheries Service, and MBARI, as well as organizations in France, Australia, Palau, and New Zealand. He has been on many deep-sea cruises, including submersible work in the Bahamas and Hawaii as well as more conventional scientific cruises in Antarctica, Alaska, as well as off Monterey, California. He is also the author of the Echinoblog, an echinoderm-themed blog. This will be his first trip on the Western Flyer.
Soureya recently received her bachelor's degree in general geology in Munich. She gained field experience related to volcanology during a campaign to Colima volcano in Mexico, where she looked at pyroclastic flow and block-and-ash flow deposits, did detailed stratigraphic logs, and performed density measurements in the field. She also participated in a field trip to Etna, Vulcano, Lipari, and Stromboli volcanoes where she was shown the different aspects of Italian volcanism. After these terrestrial experiences she is now looking forward to discovering more about submarine volcanism. She will benefit greatly from participating in this cruise, as it is highly complementary to her university education.
Levin Castillo-Guimond finished a BSc-Honour's degree in Earth Sciences at University of Quebec in Chicoutimi (UQAC-2009). His prime interest was on the physical volcanology of Archean mafic and felsic submarine successions, as they are often associated with volcanic massive sulfide deposits (VMS). In addition, to better understand large-scale caldera evolution and pyroclastic processes, Levin participated on a field trip in autumn 2007 on the island of Tenerife (Canary Islands). In summer 2009 he worked for an exploration focusing on gold and uranium deposits.
Gillian recently received her BSc-Honours degree in Marine Biology in Brisbane, Australia. She gained diving field experience while observing fish behavior on the Great Barrier Reef. On previous research cruises, she has assisted in the processing of collected organisms and in the collection and analysis of underwater video to identify the benthic life present on flows over an age series. On this cruise, she will assist in the collection of underwater video and hydrothermal clams and tubeworms, and aims to gain a better understanding of the diversity of animals living at these sites. |
