Monterey Bay Aquarium Research Institute

West Coast Expedition
July 20 - August 30, 2002
West Coast of North America
Cruise History & Purpose

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Leg 1

Cruise Dates: July 20, 2002 - August 2, 2002
Cruise Location: Northern California
Ship: R/V Western Flyer
Chief Scientists: David Clague, Jeff Drazen, Rob Zierenberg, Jim McClain
Scheduled Start Time: 2002-07-20 2000 Local Moss Landing time
Scheduled End Time : 2002-08-02 TBD Local Moss Landing time
(Subtract 7 hours during PDT to convert to local time, subtract 8 hours during PST)

Purpose: The cruise is a combination of 11 dives for four groups. Four dives are MBARI dives for the Submarine Volcanism Project for Clague, Three each are funded by NURP to Rob Zierenberg and to Jim McClain to explore two active hydrothermal vent sites, and one is an MBARI dive for the Midwater Biology Project for Jeff Drazen. The Submarine Volcanism dives are to continue work on eruption of vesicular mid-ocean ridge basalt and submarine strombolian eruptions and ejecta dispersal, whereas the final dive is to determine the geochemical variations in lavas exposed within the caldera-bounding faults on one of the President Jackson Seamounts. The NURP funded hydrothermal dives are to collect water samples from two previously sampled hydrothermal vent sites to evaluate changes over time and to map the extent and structural setting of the Seacliff hydrothermal site. The Midwater Biology dive is to observe brooding blob sculpins and detemine if abundant octopus in the same area are also brooding eggs.

Required Equipment: Manipulator, drawer with partitions, pushcores with and without catchers, high-temperature water bottles, temperature probe, bio box to fit in drawer, glass suction sampler, biologic suction sampler with screen (both suction samplers at once if possible). Night operations may utilize the rock crusher with MPR self contained-CTDs clamped to wire. Maximum of 4 elevator deployments.

Planned track/Site: Locations will be entered in database.

Dive 1 on Mendocino Escarpment for Jeff Drazen.
Dive 2 at NESCA for Rob Zierenberg
Dive 3 at north end of Escanaba Trough for Clague.
Dive 4 at NESCA for Zierenberg.
Dive 5 at President Jackson Seamounts for Clague.
Dive 6 on Gorda Ridge axis near 42.5°N for Clague.
Dive 7 on Gorda Ridge axis near 42.7°N for Clague.
Dive 8 at Seacliff hydrothermal site for McClain.
Dive 9 at Seacliff hydrothermal site for McClain.
Dive 10 at Seacliff hydrothermal site for McClain.
Dive 11 at Seacliff hydrothermal site for Zierenberg.

Participants: Dave Clague, Rob Zierenberg (UC Davis), Jim McClain (UC Davis), Karen von Damm (U. New Hampshire), Eric Olsen (U.Washington), Janet Voight(Field Museum of Chicago), Jenny Paduan, Shana Dreyfuss (UC Davis), Ellen Avery (UC Davis), Robbie Young, Sierra Senyak.

Leg 2

Cruise Dates: July 20, 2002 - August 2, 2002
Cruise Location: Northern California
Ship: R/V Western Flyer
Chief Scientists: Debra Stakes
Scheduled Start Time: 2002-08-05 0700 Local Moss Landing time
Scheduled End Time : 2002-08-10 1630 Local Moss Landing time
(Subtract 7 hours during PDT to convert to local time, subtract 8 hours during PST)

Purpose: The objective of this cruise is to 1) sample both high and low temperature vents for fluids, precipitates and microbes; 2) conduct geological transects of the southern Juan de Fuca ridge from the ridge axis to the outermost ridge flanks.

Required Equipment: We will use standard benthic toolsled for all dives. Will carry the Tivey magnetometer, ICL and temperature probes for all dives. Will use modified radium sampler for low-temperature fluids. Will also use Seewald gas tight fluid samplers and WHOI Ti-syringe samplers. Will need to use elevators for first two dives to recover fluid samplers and sulfide at beginning of dive. Will also use Tiburon wax push cores.

Planned track/Site:

Dive 1 will begin at the Flyer Vent field discovered in 2000 at Long-130.36659; Lat. 44.5671. Fluid samples and particulates will be collected. Samplers will be sent to surface in elevator. Dive will continue east as time permits collecting rocks.
Dive 2 will begin at Vent 1, a 275C sulfide structure at Long -130.363552 and Lat 44.658740. We will collect fluid samples and a large piece of sulfide to be put into a biobox in the elevator. Fluid samplers and sulfide to be sent to surface in elevator. Continue east as time permits collecting rocks.
Dive 3 will be a geological traverse that begins at approximately Long -130.3272 Lat 44.7752 and continues to the west collecting rocks. 
Dive 4 will be a geological traverse that begins at approximately Long -130.3945; Lat.44.5962 and continues to the west collecting rocks.

Participants: MBARI: Debra Stakes, Tony Ramirez, Bethany Schaarschmidt, Paul McGill, Ed Delong, Geoff Wheat, Kevin Gomes. University of Florida: Mike Perfit. WHOI: Meg Tivey, Maurice Tivey, Peter Saccacio.

Leg 3

Cruise Dates: July 20, 2002 - August 2, 2002
Cruise Location: Northern California
Ship: R/V Western Flyer
Chief Scientists: John Delaney
Scheduled Start Time: 2002-08-14 0700 Local Moss Landing time
Scheduled End Time : 2002-08-27 1630 Local Moss Landing time
(Subtract 7 hours during PDT to convert to local time, subtract 8 hours during PST)

Purpose: Preliminary establishment of Keck proto-Neptune Observatories on the Endeavour Segment of the Juan de Fuca Ridge and near the eastern intersection of the Nootka Fault and western margin off of Vancouver Island. At Endeavour we will establish up to six core holes for short period seismometers, explore sediment ponds for 2 broad band seismometer deployments, take fluid, rock, and microbial samples, and conduct a drilling-sulfide microbial incubator experiment on Endeavour. Following the first 6 dives at Endeavour, we will explore the two mud volcanoes "Maquinna and Haggis" along the Nootka fault. If the sites are venting we will take fluid, sediment, rock, microbial samples, then move to the margin to explore for sites of venting and alternative observatory sites.

Required Equipment: CTD with rosette niskin bottles, transmissometer, oxygen, (etc-standard sensors) for at least 2600-3000 m water depth, Tiburon high and low temperature probes, titanium major fluid samplers, benthic sled, drill sled, push cores, wax cores, small elevator, homer pros 6 for Keck + at least 5 additional, Sonardyne Compaq, vacuum to clean out holes, plugs for coreholes, Al Bradley model 4" ICL, appropriate core liners, drill bits, at lest 6 extra "regular" push core sleeves, at least 2 science ports to bring data up wire from Tiburon. (temperature-resistivity probe and sulfide insert will use ICL, UW high temperature probe will need a port), annotated video on UW copy, cool pix camera, modified Kraft arm for water sampling, radium sampler. Instruments the UW is bringing out to use/deploy include: gas-tight fluid samplers, temperature-resistivity probe, 23" sulfide microbial incubator, metz methane sensor, high-temperature probe, vent site markers. 

Planned track/Site:

Endeavour: 129 05.00', 47 55.00'
Nootka: 128 00.00', 49 00.00' 

Participants: U.W.: John R. Delaney, Deborah S. Kelley, William Wilcock, Marvin D. Lilley, Mitch Elend. MBARI: Debra Stakes, Tony Ramirez, Peter Girguis, Randy Prickett. Carnegie Inst. of Wash.: John D. Frantz. University of Victoria: Claire Currie

 

Cruise History and Background

Leg 1

The history of the Gorda Ridge leg is long and complicated. The cruise includes dives for 4 different programs-two funded through NURP. The NURP programs were born as proposals to explore two different hydrothermal systems that are unique-one because the hydrothermal activity is in a sediment-filled region where magma was injected into the sediment, the other because it is off-axis, high on the fault-bounded valley walls of the mid-ocean ridge. I have been working along the Gorda Ridge since 1983, although the scientific questions keep changing as we learn more and more. During our cruise in 2000 we discovered that eruptions at Gorda Ridge produce mildly explosive lava fragments as magmatic gas escapes from the erupting lava. We are trying to learn more about how this happens and how the particles are then distributed around the eruption sites. We also discovered some very gas-bubble rich lavas and are returning to try to locate the flows of these unusual mid-ocean ridge lavas. We are also doing one dive to explore the feasibility of sampling up the inner walls of calderas on some near-ridge seamounts in advance of proposing a major effort to evaluate the time variations in lava chemistry and eruptive style at such seamounts. The final dive was added late to return to a site on the Mendocino escarpment where blob sculpins were observed brooding eggs during geologic dives. The new dive will focus on the fish instead of the rocks in the area.

Leg 2

The southern Juan de Fuca ridge is an ideal spot to study the processes that create oceanic crust at mid-ocean ridges. It is an intermediate rate ridge crest, so most of the activity is within 3-4 km of the spreading axis. The magnetic anomalies and the structures are very symmetrical suggesting that it would follow our simple model. The southern end of the spreading axis is terminated by the Blanco Transform Zone, which provides some exposures into the interior of the crust. It has been assumed that oceanic crust forms as magma wells up from the mantle at the mid-ocean ridge. Most of the volcanic activity appears to be well-constrained to within the axis of the spreading ridge, with only faulting dismembering the crust with age and distance. During periods of robust magmatism, larger volumes of lava would pile into pillows and massive flows to create elongate ridges. Seafloor spreading would then split these ridges apart, send half to one side and half to the other. Finer scale studies, however, have suggested that this is not all the story. Very young-looking lavas have been found far from the axis, suggesting that they have flowed a very long distance or erupted off-axis. Studies of the magnetic intensity of the Juan de Fuca Ridge have also suggested that only half the crust is really present right at the spreading axis. Additional magma must be added somewhere to made a complete section of crust that would be characteristic of most of the seafloor. Our dives in 2000 found piles of younger lavas piled onto the edges of faults and fissures. We suggest that these actually erupted up the faults not at the spreading axis. These younger lavas form the upper portion of the crust and appear to be a hydraulic cap for low-temperature venting that we discovered in 2000. These 20 degree Celsius vents are 3 km to the east of the spreading axis. During the first dive we hope to sample the fluids and collect more evidence about their origins.

Click on the links above to find out more about this exciting cruise!