26 April, 1999
As I shared yesterday, the ZAPS sled was used last night and this morning to trace out a search pattern over a broad horizontal area. When 7:30 AM arrived and we had not detected the vertical portion of the plume, we hauled it up and called it a morning. Time to let the “rock” people have their turn! The “rock” people are the team members who are primarily equipped to take physical samples from the ocean floor, whether by dredging, employing the TV Grab (after having conducted a video survey with the OFOS), or taking a “crisco” sample (a modified gravity core which is a heavy pipe-like structure that is usually driven into the sediments to obtain a profile of the different layers. Scientists sometimes put a plug of wax in the tip of this device to pick up surface rocks, which stick into the wax. Dr. Randy Keller has substituted vegetable shortening for the wax, which have the same consistency in the cold Antarctic water, but the shortening is much easier to work with when warmed. When it strikes the ocean floor, fresh glass from volcanic rocks will stick to the crisco and can be brought back to the surface for study). Because each group (ZAPS and Rock) must hang their instruments over the side, it is not possible for both to work at the same time due to safety and operational issues.
When I talked to Dr. Keller about his interest in bottom sampling, he shared with me his fascination with how volcanoes are formed and why they erupt. He is parcticularly interested here in the Bransfield Strait with how the sediments and rocks of the ocean floor may be recycled. If you will recall from a few days ago (April 22), I mentioned two plates colliding, one sliding under the other. Dr. Keller is interested in how the plate that is pushed under is remelted and returned to the surface by volcanic processes. Of parcticular interest to him is the difference between the volcanic processes that have produced the South Shetland Islands (King George Island, Elephant Island) and the basin formations (Deception Island, Bridgeman Island, and our recent hang out, Hook Ridge). By dredging rocks from various locations and conducting chemical and physical analyses on them, he and his colleagues will be able to postulate the times and conditions of their production.
I asked Dr. Keller how he got started with this field. He shared that when he was young, he used to go camping out west. Then when he went to college at the University of Florida (interested initially in engineering) he took a course in botany and another in geology before he realized he had a real interest in field science. He made his major geology and minored in botany and then went to OSU for his Masters degree in geological oceanography (marine geology). I was really interested to know that he had lived in Krakow, Poland on a Fullbright Fellowship to the Polish Academy of Sciences for almost two years after his Masters degree, during which time he parcticipated in a Polish expedition to the Bransfield Strait (this is now his fourth expedition here!). After returning to OSU for his Ph.D., Dr. Keller worked at University of Tennessee before once again returning to Oregon, this time to work as a research professor and joint coordinator for the RIDGE Office, which brings us back to the current cruise.
I awoke at noon to see on my cabin monitor the TV Grab being retrieved onto the deck. While I was dressing, the phone rang and someone said, “we’ve got hot mud!” I hustled out to the deck in full gear to greet an excited, but extremely engaged group. They each had a parcticular task to accomplish, whether this be to obtain a sub-core of the sediments (a vertical profile or snapshot of the layering of the sediment) or to sieve it for organisms. The types of organisms can be used as indicators of the immediate environment. If a parcticular organism is found (tube worms for instance) this may be an indicator of the proximity of a vent. I joined the Europeans in the science cooler (a big walk-in refrigerator that allows cold samples to be prepared or preserved for analysis at temperatures near those of their origin) where we pressed the sediment samples for the pore water, taking the pH and temperature of each slice approximately 1-3 cm thick. Though the water at the bottom was close to 1 Celsius, this sediment was close to +10 Celsius! We must be getting close!
Following the realization of the sediment’s elevated temperature, the OFOS sled was immediately prepared for redeployment to obtain a better video survey of this region, The survey took 4 hours and after that we convened in the dry lab to plan the ZAPS deployment and the sampling strategy for the evening.
I stood out on the side deck, staring into the dark water, feeling the impertinent wind against my face. Looking into the water I was impressed by its seemingly absolute coldness…Absolute in that the sheer volume spoke of unflinching immutability. If one were to fall into its grasp, how quickly it would quench the fire of life. There was no thought of mercy, no hope of warming. The fact that 50 megawatts of thermal power in the form of 300 Celsius water can spew out of the vent at 3 m/s and still be dissipated so rapidly that the difference in temperature from the surrounding water is quickly reduced to a mere tenth of a degree Celsius is incomprehensible. Yet, this frigid water would ultimately meet its equal adversary in the primary fire of all life, our sun - for the waters do warm, and ocean currents circulate because of this heating and cooling
Well, that’s going do for tonight,
Incidentally, I was able to bring the student weather station up today and will report their data along with the ship based data I have been recording. A cursory glance indicates fairly decent results, but an interesting experiment for you to try is to graph the student built station’s data versus the ship’s data. A perfect match would result in a diagonal line (45 degrees or a slope of 1). If you graph the student data on the y-axis and the ship data on the x-axis, then the line will be more steep (lies above a 45 degree line) if the student station is systematically reporting values too high. Likewise, if the line is shallow (lies below the 45 degree line), the student station is systematically reporting values too low. Either of these cases could be corrected for by adding a little math to the computer program and would probably indicate that the calibration of the probes, done where it was a little warmer, needed tweaking. Incidentally, the probes are from Vernier Software of Portland, Oregon. A big thanks to David Vernier and his company for filling our order so promptly and providing all the technical assistance we needed to incorporate them into our weather station!
(I’ve changed the format due to complaints about tabs and spacing) Latitude (S): 62 10.7 Longitude (W): 57 13.6 Time (GMT): 1824
Depth (m): 1386 Temp (C ): 3 Barometer (mbars): 1006
Wind Speed (m/s, knots): 14.9 29 Wind Direction (degrees): 264
Salinity (ppt): 34.1 Relative Humidity (%): 91.9
Pressure (mBar) Relative Humidity (%) Temperature (C)
1007.9 85 2.8
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