Alvin Dive 3360 - 21 February, 1999

Port Observer: John Sinton
With Linda Popels and Pilot Bob Waters

Launch Position:

Time Depth Hdg
~0805 Alvin in the water
0833 1204 Beginning maggie spins in water column; 1 deg/sec, spinning clockwise.
0925 2710 035 Bottom just coming into view.
0926 2705 034 About 5 m off bottom. Bottom is pillow lava with quite a bit of relief on it. It has a uniform coating of sediment on it but no real pockets of sediment in lows between pillows.
0927 073 Pillow lava is budded and striated and has at least 1 m of relief between pillows. All surfaces have sediment on it. Not real glassy, except on buds.
0938 2707 Sample #1; Large bud that broke into several pieces when put into basket.
0941 2705 080 Moving off after taking sample # 1. On a slope constructed of pillow flows, sloping down to west. Some pillows elongate. No faults or fissures anywhere.
0944 2699 085 Going upslope obliquely. Fair number of buds buy not real highly ornamented lava.
0947 2691 083 Still in same lava, quite bulbous pillows here as we move obliquely up hill. No change in sediment cover.
0948 2684 082 Slope getting a bit steeper here. Good striations and some elongation downhill. Maybe more buds here.
0951 2669 083 Slope maybe decreasing a bit here. Same striated pillow flow with uniform sediment coating.
0952 2662 083 Large pillows more than 1 m in diameter, lots of buds/ 1-2 m of relief on pillows.
0955 2652 083 Same flow, but maybe ever so slightly glassier here. Pillow diameter about 2 m here.
0958 2643 082 Still coming up constructional slope in same pillow flow.
1001 2632 082 Elongate pillows up to several meters long. Maybe slightly glassier here, but almost certainly the same flow we started in.
1004 2628 084 Same flow. Some staining on cracks in pillows. Good buds; good striations.
1007 2617 083 Same flow, same buds, same everything.
1013 2600 081 Maybe into a slightly younger flow here, as it looks somewhat glassier, but no apparent contact was crossed. Pillow forms look very similar to those before.
1021 2595 Sample #2: pillow bud from this flow. Looks slightly glassier and maybe more buds that flow we started in. Sediment cover appears to be somewhat less although it still pretty much coats all surfaces, it looks thinner and the lava definitely looks glassier. Going to continue going up slope.
1024 2589 070 Certainly looks like a slightly younger flow than that we started in. Very slight coating of sediment.
1026 2583 051 Moving up through somewhat younger pillow flow with shiny buds on it. Sediment starting to look a bit patchy.
1028 2578 052 Some collapsed pillows here.
1029 2575 052 Some glassy lobate lavas here, mixed lobates and pillows. Then crossing a contact with some definitely much younger lava. Younger lava is much glassier and much less sedimented. Younger lava is pillow lava.
1032 2573 051 Definitely in younger lava, which here has become a lobate lava.
1034 2571 050 Very shiny surfaces, somewhat lobate. Sediment is in patches and some low-lying areas and not uniformly covering all surfaces.
1045 Been looking for a place to sample on these lobate lavas; buds are small.
1049 2572 Sample #3. Small bud from glassy lobate lava. Lava here is transitional between lobate and pillow lava. Should be close to WP 2.
1054 160 Lobate lava with some pillow around. As we move off we see definite lobate lava with no buds.
Mistakenly went off at 160 for a ways and now turning to go 060. Location appears to be ­0692; -6466. Not more than 50-100 m SE of sample #2 location and about 400 m from WP3.
1059 2579 056 Large collaps here = side of channel structure. Has bathtub rings on the side of it. Has sheet flows in the center bottom of it. Also has some pillars, especially near the sides. Depth is at least 3-4 meter. Bottom is folded sheets, locally becoming jumbled sheets.
1101 2571 Swinging around more to north in order to follow channel.
1103 2572 254 Channel is full of pillars and bathtub rings. Appears to come to a dead end in this direction. Surface outside of the collapes is lobate, that also have some smaller collapse pits in them.
1107 2571 067 Moving toward WP 3. Probably on north side of channels. In glassy lobate lavas, patchy sediment on it. Here, mostly no collapse structures present.
1109 2571 065 Beginning to see some small collapses in the lobate lava. About 300 m from WP 3.
1112 2571 071 About 250 m from WP 3. Lobate lavas with very small buds. Some lobes are almost 1 m thick and this lava is almost transitional into pillows. Mostly uncollapsed here.
1115 2569 075 Just coming into channel structure again. Collapsed lobates on port side, channel is on stbd side. Bathtub rings on side and pillars just inside rim. This one is at least 5-6 m deep. Appears to have tube-like re-entrants in the walls.
1117 2571 075 Center of channel has folded sheet flow.
1118 Looking to sample sheet flow.
1124 2574 Sample #4. Sheet flow from channel bottom. Sides are all bathtub rings and pillars with excellent selvedges. Looks like there was a real flood of lava through this system at one time. Note depth here is about 5 m below where we crossed over the rim.
1126 2571 Still following sheet flows in the middle of the channel. Much time is spent looking at a big octopus with ears.
1129 2569 070 About 6 m off bottom. Sheet flows in middle are turning into very flat sheets although there are still some folded sheets here. Can see evidence for slight subsidence in some of the flatter sheets. Local lineations in some of the flatter sheets. Probably less than 100 m from WP 3.
1131 2573 100 Channel is bending around into the axis. Bottom is very smoot sheet flows although there still are some folded sheets around.
1132 2572 Near intersection with the axial trough. Swinging around to south.
1135 2567 On edge of collapse (5 m above last depth). Direction to WP 4 is 182, so must be in axial collapse zone. Sheet flows on bottom. My estimate is bottom is about 6 m below us.
1137 2573 189 Coming up out of narrow collapse structure with bathtub and pillars. Base of wall is collapsed lobate debris, but floor is sheet lava.
1139 2572 189 Just went by a very large pillar about 4 m in diameter. Coming to end of a one of the collapse structures. As we come up it appears that this one is about 6 m deep.
1141 2567 191 East side of axis, with some collapsed lobate below us.
1143 2568 137 Have come easterly for a while as we followed a collapse zone that is about 9 m deep. Now going to go more to south.
1145 2569 284 Went westerly for a bit. We are over a very wide collapse zone.
1147 2567 Should be near to WP 4.
1149 2568 189 Moving along west side of deep crack that is 8-9 m deep.
1151 2568 Turning east over trough.
1156 2570 Sample #5. Piece of lobate crust from top of east edge of trough. Pillars near here are about 1 m in diameter.
1158 2568 113 Some spaghetti worms on east side of the axis. Also some white staining on cracks in lobate lavas. There are local collapses in these lobate lavas.
1200 2570 113 Starting to see some budded pillows in this flow. Bottom is deepening in this direction and lavas are getting less fluid looking. Pillows are up to 2 m across, mixed with lobates.
1203 2574 110 Just set down while we look for a ground in the system somewhere.
1205 2573 113 Moving off in glassy lobate lava with a few buds. Patchy sediment.
1207 2576 113 Now into pillow lava with very glassy buds on it. Almost certainly the same lava flow we have been following but it is now much less fluid than closer to the axis. Just beginning to see a channel structure with sheet flows in it and lobate and pillow lavas on the side. The channel structure was going almost N-S where we crossed it.
1210 2580 110 Now into pillow lava with good buds. Might be some older surfaces below the pillows but that is not at all clear. Also some lobates around and we appear to be near a pillow to lobate transition.
1214 2590 113 Mixed lobate and sheet flows here. Looks like same flow we have been in in terms of age. Lots of glass showing through.
1216 2592 112 Crossing a sheet flow that is jumbled here and then back into some more lobates. WP 5 is due east of us. Can still see the jumbled sheet flows that are very broken up and chaotically jumbled.
1218 2597 105 Following a lava channel parallel to this heading. It has jumbled sheet flow in the channel with lobate and pillow lava on the margins.
1221 2604 107 Still following channel on port side. We are over lobate lava on the margin; the channel interior is very contorted, jumbled sheet flow. Lobate levee-like structure is about 1-2 m high.
1222 2606 107 Still following channel which widens here to 10-15 m wide, and several meters deep. It seems to go underground here under a lobate surface.
1224 2609 106 In lobate lavas with some pillows around. Some lobates are collapsed into small pits about _ m deep.
1226 2613 106 Still in very glassy lava, transitional between lobate and pillow lava.
1229 2620 106 Budded pillows here with patchy sediment.
1231 2627 Just crossed contact and turned to 152, parallel to contact. Begin looking for place to sample the older lava. Older lava is lobate lava, with much younger budded pillow lava on top of it.
1309 2630 Sample #6. Small bud from where the older lava is slightly pillowed. Moving off toward WP6.
1311 2624 261 Coming back through our own stirred up sediment cloud. Flying about 5 m off bottom.
1313 Crossing contact into younger pillow lavas.
1314 2620 260 Young pillow lavas here.
1314 2618 260 Young pillow lavas.
1318 2617 261 Crossed contact into older lava again. There is uniform sediment over this older lava. We are about 900 m from WP6.
1321 2611 262 This older flow has consistent sediment cover. It is a budded and striated pillow flow.
1323 2605 262 Still in old lavas, but becoming more lobate like here. The sediment cover is at least a couple mm thick on the flatter surfaces.
1325 2603 259 Starting to see some collapse pits in this older, sedimented lobate flow.
1327 2602 261 Lobate changing into pillows. Some of the pillows appear to lie on top of the lobates but there is not much (any?) difference in age between them.
1330 1596 261 Still in sedimented, budded pillow flow. No real pockets of sediment in the lower part of the flow but there is a uniform coating of sediment on all surfaces.
1333 2589 261 Sedimented pillow flow is becoming very lobated up slope with lower relief and fewer buds.
1336 2584 260 Just crossed contact with much younger pillow lava over the older, more sedimented lobate lavas. Contact here runs almost parallel to submarine heading here. We are about 300 m from next WP. There is a finger of older lava that trends parallel to 260 but with younger lavas on either side of it. Younger flow if fairly thin (< 1 pillow thick) here. Then all older lava disappears beneath younger lava.
1338 2579 261 Looking to sample
1345 2579 Sample #7. Bud from younger pillow flow. Going to head off to WP8 at a bearing of about 200.
1348 2578 200 We are about 400 m from WP8 at bearing of 205.
1350 2577 204 Young glassy lobate lava with local pillows, which have lots of buds where present. Pillows look like they could be just ooze outs from the lobate lavas. Sediment occurs only in patches some cm across.
1353 2575 205 Come up gradually, almost flat here. Lobate lavas with some pillows up to several meters across.
1356 2572 205 Now almost all pillows, without lobate lavas.
1359 2573 206 Pillows gave way to lobate lava here. Depth changes are due to different sub depth, not bottom depth. No real difference in sediment cover.
1401 2569 203 Coming up very slightly, and starting to see spaghetti worms on this lobate lava that has some small collapse pits. No fissures present.
Seeing some lava that looks slightly younger here and some more spaghetti worms.
There is a collapse pit to our SW as we move over some lavas that are almost sheet lavas. This pit has younger lava pouring over the edge and down into the pit. The pit is about 15 m across.
Sample # 8. Sample of younger lava tongue.
1415 2571 In a small collapse pit that has a small tongue of lava that pours into the pit. There is little difference in age between the lava that is and the one that pours into the pit.
1417 2570 153 Swinging around to 160. Young lava and lots of collapses near here.
1418 2570 160 Maybe some slightly younger lava here, but the difference is quite slight. Some spaghetti worms around.
1420 2569 160 Several collapses up to about 3-4 m across, down about _ meter. Maybe more than one lava age here.
1422 2571 161 Maybe getting slightly deeper in this direction and might have more than one age lava.
1423 2571 About 5 m off bottom. Turning to south
1426 2573 185 Still about 5 m off bottom. Bottom appears to shallow to stbd, suggesting that we are just to the east of the axis. Maybe shoaling slightly as we go. Lava here is quite young with only patchy sediment on glassy surface and good buds all around.
1428 2573 187 Rather flat here, in a massive pillow lava, young and glassy and spots of sediment here and there. Several meters of relief on pillows. Some are drained and/or slightly collapsed.
1430 2576 218 In massive pillow flow. Running about 4 m off bottom. Rocks are quite glassy and only lightly dusted with sediment.
1433 2577 283 Pillow flow appears to be flowing down from the north. We are on a bearing of about 200 from WP 9. Pillow lava with lots of buds.
1436 2572 240 Now pretty much on top of axis. Some collapse and slightly more lobate forms here.
1437 2571 200 Should be right on crest of bathymetric axis but no fissures here at all, just massive pillow lava and some lobates.
1439 2570 184 Back into just pillow lava here, with good glassy buds. Some dusting and patches of sediment only.
1444 2572 185 Settling down to take sample. Slightly more lobate lava.
1450 2572 Sample #9. Piece of pillow/lobate lava here. Weights away; leaving the bottom.