Alvin Dive 3344 - Feb 3, 1999

Transcript by Ken Macdonald

Transcript follows: [back to dive track]

955 on bottom: landed on the east edge of the overlapping spreading center basin near 18 35S, 2779m; bulbous pillows with delicate glassy ornaments and buds, dusting of sediment but pockets of sediment are not well developed, age ~1.5. Lots of longitudinal striations on the pillows, breadcrust texture. Very glassy and black in appearance. A number of the pillows have broken open and have internal ledges and spill outs that are sheets on a small scale.

1016 moving up slope for sample R1

1017-21 stopped to collect both samples R1 and R2 from this area of age 1.5 bulbous pillow lavas.

1021 underway heading 121, still age 1.5 bulbous pillows

  1. 2750m; transition to more elongate pillows, still age 1.5, fissure parallel to spreading center appears to be overrun by these age 1.5 pillow lavas. ~1 m wide.

1027 heading 121 some of the pillows have cracks which cut across them lined in white, anhydrite staining?? ~1/2 m wide fissure.

1030 mix of bulbous and elongate pillows age 1.5 ; several fish, crinoid.

1038 on the summit now at 2714m, mostly bulbous pillows a few elongate , same age 1.5 flow, now heading downslope toward S. [back to dive track]

1044 at top of a pillow mound, breadcrust texture on bulbous pillows very common.

1048 heading downslope on this pillow mound, lots of bud and glassy ornaments on the pillows, 2765m, heading toward waypoint 2. Could be age 1 here, a younger pillow flow??

1052 contact with jumbled sheet flows and areas of collapse. Age 1-1.5.

1055 folded sheet flows and lobate flows, still age 1-1.5, 2786m, at waypoint 2 on E side of axis.

1056 back to bulbous and elongate pillows of age 1-1.5

1058 stopping for sample R3 in age 1-2 area, still lots of glassy ornaments but perhaps a bit more sediment. [back to dive track]

1107 underway again, just crossed into area of intensely folded and jumbled pillow lavas so R3 was taken right near the contact between the sheet flows and pillows.

1108 already back into pillows again . Criss-crossing the contact, my guess is that the sheet flows locally lie on top of the pillow lavas and are ever so slightly younger, sheets are age 1 while the pillows are more like 1.5?? The sheet flows appear to lap up onto the edges of small bulbous pillow "kipukas."

1111 heading 238, going up hill on another pillow mound depth 2776m. Bulbous pillows age 1.5.

1113 large anemone about 1 m across!

  1. still climbing up pillow mound, age 1.5 pillows. [back to dive track]

1118 2738 m, approaching summit of pillow mound, age 1.5 pillows.

1122 2718m, heading 266 to waypoint 3 , near summit of mound.

1123 at summit at 2714m, still age 1.5 pillows. Heading 280.

1125 stopping for sample R3. 2716 m.

1131 underway again 261º to waypoint 3. Still age 1.5 pillows. [back to dive track]

1132 crossed 1/2m wide fissure trending ~N-S cutting through pillows.

1133-35 a local tongue of lobates with local collapses, folded sheet flows of age 1-1.5. , then immediately back into age 1.5 pillows.

1142 near waypoint 3 now, have been going down the west slope of the pillow mound that we sampled, age 1.5 pillows, lots of glassy buds.

1146 heading 164 toward waypoint 5, we are skipping waypoint 4 because we want to go in a more ridge parallel direction. 2715m. Age 1.5 pillows still.

1148 heading 163, 2710 m [back to dive track]

1150 lots of white staining on cracks that transect pillows of age 1.5, 2707m.

  1. crossed tip of 1/4m wide fissure cutting through pillows and later lobates. Some collapse develops along this fissure.
  2. stopping for sample R5 near the collapse we just crossed, we are settling down onto age 1-1.5 pillows. , lobate flow is just behind us, 2708m.
  3. anemone perched on glassy pillow bud, on station, sampling a glassy bud here.

1207 underway again, 2705m, age 1.5 pillow unit.

1210 1-1.5m wide fissure trending N-S cutting through age 1.5 pillows.

1214 crossed onto lobate flow of age 1. A few wrinkled sheets.

1216 2700m, looking for sample [back to dive track]

1223 orange hydrothermal staining in lobate flow age 1. Stopped for sample R6

1230 heading 163 toward waypoint 5, underway again, 2701m. Lobate flow age 1 still.

1232 turning right away from our planned track to waypoint 5, in order to follow contact between age 1 lobates and age 1.5 pillows.

1233 back onto pillows age 1.5, lots of glassy buds, trying for sample, on gradational contact lobates/sheets.

1245 underway crossing lobate flow.

1246 lobates, folded sheet flows where there are collapses in the lobate flow.

Heading 035, 2701m.

1251 back onto age 1.5 pillows, some lobates too, contact is very gradational. Heading 040. Crinoid.

1259 looking for sample [back to dive track]

1301 back onto pillows of age 1-1.5, stopping for sample.

1308 sampling what appears to be a large pillow bud but crumbles as we grab it, its is shot through with hydrothermal alteration, white and orange staining. Now underway. 2709m toward waypoint 5.

1310 on contact again; Pillows on right , lobates on left

1314 age 1.5 pillow lavas, heading 172 back toward waypoint 5 which is about 100m away.

1316 2718m, age 1.5 pillows on starboard side, lobates over on port side.

  1. turning left to 120 to come back to lobate to pillow transition, all pillows here. 2716m

1325 still pillows age 1.5 on way to waypt 5, this east-facing flank of the spreading center appears to be all pillows. [back to dive track]

1328 we are turning toward waypt 6 about 100m before getting to waypt 5 because it is clearly all pillows over here.

1332 transition from pillows age 1.5 to lobate flow

1333 back to pillows

1337 back to lobates, 2700m

1338 back to pillows, 2690m[back to dive track]

1345 back to lobate flows

1347 edge of lava channel, jumbled sheet flows of age 1, levee about 2 m high.

1348 transition jumbled to flat and striated sheet flows in middle of lava channel, looking for sample. Age 1.

1355 Collected sample R9, now going uphill approx S to trace this lava channel to its origin. Folded sheet flows, age 1. [back to dive track]

1357 edge of channel, levee 2 m high, jumbled sheet flows bank up against the levee, levee is defined by collapse within lobate flow, I think the lobates and sheets are part of the same age 1 flow. Heading 174

1359 contact of folded to flat and striated sheet flows.

1400 there appears to be a lava channel within the wider lava channel, same flow though.

1401 several crossings going from flat and striated sheet flow to jumbled sheets, all one flow of age 1. Very glassy with just a very light dusting of sediment. Heading 130

1403 the channel origin, it starts abruptly at the edge of a breached eruptive fissure which is trending ~N-S and is ~2-3m wide. The walls are sinuous on a m scale but straight on a scale of tens of m. There are many cm wide ledges which appear to be outcrops of successive sheet flows rather than bathtub rings. The intact surface on either side of the fissure is a lobate flow of age 1, where there is collapse, the flow is a sheet flow of age one, either jumbled, folded or striated; lobate and sheets all one flow unit I think. [back to dive track]

2679m, turning S to follow the eruptive fissure.

1406 stopping to get R10 sheet flow from eruptive fissure, 2667m at rim of fissure which is ~10m deep. This sample fell into bin where R6 is and a few fragments fell into the bin just forward of R6, oops!

1412 underway along eruptive fissure heading 206 which is the source region of the lava channel we followed earlier.

1414 eruptive fissure grades into a series of isolated collapsed lava lakes tens of m in dimension. Lava pillars ~1-2m high supporting fragile roofs and remnants which are only ~10cm thick. 2678m. [back to dive track]

1420 2677m folded sheet flows grading to lobate flow of same age, still age 1. Lobate flow is on my side, stbd, and collapses in sheets on port side (Rubin). Heading 186

1421 contact of sheet flows and lobates age 1 going to pillow lavas age 1.5. 1/4m wide fissure.

1422 back to lobates and sheets of age 1. Collapsed lava lake, again it is sinuous in plan view on a meter scale, but linear N-S on tens of meter scale. Lobate flow age 1 rims the collapse, sheet fragments in floor.

  • folded sheet flows age 1, in another wide lava channel which bears ~270 heading toward the OSC basin.
  • A kipuka of age 1.5 pillows only ~2 across. Wrinkled, folded and jumbled sheets of age 1 on either side of the older kipuka of pillows. Large lava coil. Many transitions from flat to folded/jumbled sheets.
  • Another older pillow kipuka within lava channel.
  • More lava coils, still in same channel.
  • Crossed out of channel onto age 1 lobate flow. Channel was 4 minutes across, travelling at ~ 1knot or 1/2m/sec, so width of channel is ~120m?
  • Pillow lavas age 1.5, same pillow flow as earlier in this dive, I think.
  • back to striated sheet flow age 1, grading into lobate flow, in another lava channel.
  • Transition to jumbled sheet flow.age 1
  • Turning right to 040 to follow this lava channel up to its source; 2679m.
  • 093º, 2683m, intensely folded sheet flows of age 1 within lava channel.
  • Crack few cm wide cutting n-s across sheet flow,
  • Stopping for sample R11, folded sheet flow within lava channel.
  • 1439 underway again heading 081, heading up to lava channel source, 2689 m.

    1440 jumbled sheet flow age 1 [back to dive track]

    1441 human debris, a 10 foot long piece of iron pipe.

    1442 turning right to head to animal farm.

    1443 big collapse region, jumbled sheet flows. Age 1

    1444 another lava channel and then a channel within a channel. Age 1 jumbled and folded sheet flows.

    1445 2690m flat striated sheet flows

    1446 lobate age 1 flow, outside of lava channel[back to dive track]

    1447 contact; back to age 1.5 pillow lavas! Glassy buds.

    1451 heading S to animal farm, still age 1.5 pillows.

    1454 2699m some age 1.5(-2? Pehaps it looks a bit older because we are flying higher?) lobates and pillows, heading 180

    1502 still in age 1.5 pillows to lobates, some dusting of yellowish sediment which may have a hydrothermal component.

    1504 stopped to pick up sample R12 of age 1.5 lobate lava.

    1511 underway S toward animal farm, crossing collapse lava lake, age 1 jumbled sheets.

    1512 out of power and time coming up, great dive![back to dive track]

    1512 Off bottom