Alvin Dive 3354


Time Heading Alvin Depth Commentary
0929 132 2676 On the bottom. Age 3+ lobate-sheet lava form, deep sediment pockets, X
0933 168 - X 6706 Y 7516 Alt. 3-4m Curtain-Folded sheet flow, with broad 1-2m folds flowing SW-SSW. Sediment filling pockets between the folds. Also mounds, look like a tumulus (central crack - smooth surface)
0936 180 - Sample 1 (X 4109 Y5228) in curtain folded sheet flow off-axis
0943 111 2683 X:5335 Y:7431 Curtain-folded sheet flow along the inflated tumulus still heavily sedimented. Tumulus is a local topographic high of 3m
0953 270 under way after taking Sample 1, coming around clockwise to head upslope. Still heavily sedimented, and following subparellel to the linear tumuli-like highs
0958 266 2672 flying over Age 3 jumbled and curtain folded lava, local topographic highs like the previous entry
1000 267 2663 4847 7601 coming up over a tall wall trending WNW down to the N, staring to see a lot of bighead fish
1004 243 various flat and jumbled sheet flows, just as heavily sedimented as before
1005 232 2655 Tectonically broken and fissured sheet to jumbled sheet flow. Fissures here are <1m wide, but patches of breccia are abundant.
1007 200 2649 Starting to look for the place to take Sample 2 among sheet and jumbled sheets at the top of the East wall of the graben. Local topography is steep but short slopes of sub-meter-scale roughness.
1013 186 2648 Lobate-Pillow flow that appears to be in contact with the folded sheet flow at the top of the East wall X:2605 Y:5606
1015 186 2648 X:3726 Y:5607 Pillow flow with no buds
1017 239 2645 X: 3363 4957 Left the jumbled sheet flow behind, and headed over old Age3 pillow lavas with interpillow sediment pockets and no buds. Still heading upslope toward the East graben bounding fault.
1021 236 2651 Drop off, mostly intact pillow lavas that are still very old, but not as fissured as 5 minutes earlier. Appears to be a pillow mound 4-5m high but very gently sloping of 10's of m. X:3559 Y:5489
1024 2645 Looks like the same pillow lava mound, with a lot of buds but no shiny glass. A drop-off visible in the down-looking SIT camera that looks like a big fault scarp on port side X:3527 Y:5467
1027 258 2647 Tectonically torn up and truncated lobate sheet and pillow flows along what appears to be the main bouding scarp of the East Wall X:3498 Y:5384
1028 238 just came off of a 12m high scarp decending down into a lobate flow that is still heavily sedimented, just as the lava outside the graben was. X:3467 Y:5378
1032 210 2658 Stopping to take Sample 3 in a lobate flow with collapsed lobes that are 1-2m wide.
1037 237 2657 Underway after taking Sample 3 from lobate flow with local collapse. Heavy sediment in the collapses, also crinoids both swimming and stalked. Bighead fish remain common. Flying over a short drop of X:3410 Y: 5343
1043 177 2662 Just came over a drop off, at least 12 m high after taking our second step down. Sub is aligned parallel to the scarp face with stbd. view unable to see ground. SIT camera sees talus on the slope of the scarp X:3334 Y:5294
1050 178 2688 Stopping at base of the 2nd 12-15m high scarp to sample 7m high pillar. This will be Sample 4.
1055 230 2687 Underway after taking Sample 4 from the top of a 7m high pillar. Flying through a pillar and chimney field. Going to circle around this field. Many of chimneys are >8-10m high.
1058 239 2675 Climbing up a vertical scarp face. The lower 5-7m has what appear to be selvages but the upper 2m part of the ridge has truncated lobes and pillows. Its a clear tectonic feature that the lower part has some volcanic collapse, and small local drainback draping. The top of wall
1059 238 2673 Now on top of the wall to the West of the chimney and pillar field. The top of the wall had lobates with fairly thick hydrothermal sediment. The whole wall is <5m wide.
1101 243 2668 Still in tectonically fissured horst terrain. The bench seen in Seabeam is composed of a series of these steep ridges. X:3101 Y:5135 alt:10m
1103 239 2664 Tectonically broken up - Fissured terrain. Flat, broad lobate lavas, that grades into a sheet flow. All are uniformly and heavily sedimented. Out the port side can see a deep drop off. Most fissures only slightly oblique in trend to the sub's heading, so fissures trend roughly more NW-SE than expected.
1107 237 2673 Flying over the jumbled sheet flows that appear around the inner ditch of the graben. Going over a drop off that should lead to the edge of the inner ditch. On this level are heavily sedimented lobate-to-sheet flows.
1111 239 2674 Flat sedimented sheet flow after coming over fractured up broken sheet flow.
1113 237 2670 Field of pillars or maybe chimneys all around Alvin. Actually, these are chimlets, maybe 1m high? Not connected, but only a spaced a couple meters apart. Tons of sediment, mostly hydrothermal chimneys. Further along the track about 30-40m, the chimlets develop into really large hydrothermal chimneys. Several chimneys can be seen out either side, and are >10m high including their base in large hydrothermal mounds.
1115 235 2669 Winding our way through large hydrothermal field, trying to stay to constant heading of 235. These are the largest chimneys seen so far, 20m. Covered with stalked crinoids and mushroom-shaped bugs the same size as these crinoids. X:2755 Y:4907
1119 240 2671 Just over the axis of the inner ditch. Too far from the bottom to see anything even in the SIT camera (>>20m)
1123 Fractured lobates and sheets that are old. Fractures and fissures 1m or less wide. Same relative age as what formed on the bench. Either a pre-eruptive fissure or post-eruptive volcanic collapse.
1128 272 2695 In the floor of the inner ditch, just under way after collecting Sample 5 from the axis of the inner ditch. Lots of fish, and many crinoids. Lots of talus of lobates and pillows around. The West wall of the inner ditch climbs steeply and is composed of talus slope, with copious hydrothermal sediment among pillow blocks.
1137 241 2669 Talus and pillows heading up east-facing wall of the inner ditch. No selvages, no in-place outcrop.
1140 242 2649 Truncated pillows, trying to find a place to sample along the West wall of the pillows at the top of the West wall.
1145 212 2650 Just finished taking sample number 6. Pillow to lobate flows, with less hydrothermal sediment. Now turning about to take a course back across the graben.
1150 136 2679 Altitude of 30m, heading back over the inner ditch but up in the water column
1152 138 2696 Lots of hydrothermal sediment, and talus. Probably the East wall of the inner ditch. This is first good look at this wall, and it's talus (tectonic) collapse.
1157 131 2666 Flat sheet flow with small fissures and cracks running through it. Heavily sedimented, so sediment may be masking a lobate flow morphology.
1158 136 Little chimlets out the window, and a big sulfide mound. Couldn't see the top of the mound to tell if there were any chimneys there. Very small area of hydrothermal edifices. In among pillow lavas.
1200 135 2666 Crossing another tall narrow horst. Mostly pillows or bulbous lobates along the top. Same can be seen truncated in the wall of this horst. The lava is heavily sedimented, probably lobates but with little pillows sticking out.
1202 135 2672 Just came up over a large collapse, maybe 10-30m wide. Another wall in front of the sub, with talus at the base and truncated pillows and lobates in the wall. This wall is 10m+ high. Depth was 2669m when on top of the horst, with altitude of 10m from top of talus ramp.
1206 136 2665 Lobates, pillows, crinoids. Fissures breaking up the lobates, but not creating vertical relief. Individual lobes are collapsed in 2m wide, <1m deep holes. Some of the lobates are broken up. A lot of sediments.
1207 137 2665 Crossing over a horst, on the top are lobates with thick (hydrothermal) sediment. The top is only 3-4m wide. The bottom of the opposite side is floored with sedimented pillow lavas and breccia.
1208 135 2667 Just passed over a field of small hydrothermal chimlets, not more than 2-3m high. Currently flying at 7m altitude.
1212 176 2668 Settling down to take sample 7. On the top of the horst, sampling a lobate chunk.
1218 140 2666 Underway again after sampling from the top of one of the many horsts. This one near the East side of the graben floor. Drop off floored with talus, noticable pillow talus. X:2933 Y:4356
1221 143 2676 No chimneys in down-looking SIT, but fissures and shadows are abundant. 2-3m wide horsts with 5-10m high walls. Fissures here are at all scales from <1 to >5m wide. Cracks in the top of sheet flow too. Very fractal fissuring along here.
1223 141 2674 Lobate flow broke up into talus. Just momentarily, then lobate flows with just some cracks returns. Instead of large drops and horsts, the terrain is more broken up by meter-scale fissures and cracks.
1227 139 2669 Horst benches seem a lot wider than the grabens between them. Horst tops are heavily sedimented, but probably lobate lavas beneath all the dirt.
1230 138 2657 Heading upslope. Meter-wide fissures in pillows with buds and lobates. All still old (Age 3). In the SIT cam, the fissures are floored by talus blocks of 10-50 cm size.
1232 144 2650 Found the East wall of the graben again. Pillows, sediment pockets between them, but these pillows have plenty of buds. These pillow lavas flowed down this slope from toward SE, and could be younger than the other units seen on this dive. X:3191 Y:4051
1246 245 2652 Underway now after collecting Sample 8 from this budded pillow flow. Headed back across the bench, can still see flow direction in the videos. X:3193 Y:4022
1250 242 2647 Just crossed over 10-14m high drop off truncating the budded pillow flow. On the other side is still in the pillow flow, but the pillow buds on this side are rare compared to the other side of that horst-graben. X:3145 Y:3997
1254 242 2662 Flying way way high over the graben, over 20m altitude, between 1253-1256
1257 246 2676 Out of the pillow flow. It's lobates that are locally collapsed. Sediment is abundant, age 3, thick pockets.
1259 243 2682 Curtain-folded sheet flow. Over 1m of local relief, small 10m wavelength highs and lows. Sheet flow is fissured up and tectonically brecciated in places.
1303 155 2677 Turning parallel to a small 1m wide crack with little hydrothermal chimneys inside. Lots of hydrothermal sediment, covering the lava flow. Lava morphology still looks curtain folded.
1307 245 2673 Lobate to sheet flow contact. Trying to sample some of the sheet flow that we think is just at the edge of the ditch.
1312 233 2673 Underway after taking Sample 9 from the sheet flow - lobate flow contact.
1313 233 2671 Flying over a shelf on the east side of the inner ditch. Several small pillars or chimlets (max. 3m high). We are descending into the inner ditch to get a better look the these features. The pan-tilt camera is stuck in a uplooking useless position.
1315 241 2676 Can see several large pillars with selvages and selvages in the wall. Paleo-lava-lake level must have been >>3 m, but can't really see higher up the wall out the observer porthole.
1320 240 2677 Inside the selvadged collapse on the eastern edge of the inner ditch. Just took a sample from a top of a pillar here. Should be Sample 10. The pillars all look to be 3-4 m high, and the collapse puka was also roughly the same depth.
1323 256 2670 Pillow lavas, and some small chimlets. The pillows run over and into a collapse to the west of us now.
1326 230 2668 Rubble at the base of the 10m high scarp separting the pillow lavas from the inner ditch. This is a fault scarp, not a volcanic collapse like the puka with the pillars in it.
1330 265 2678 Now at the bottom of the inner ditch. In a field of large dead chimneys. Many are chimlets on top of low sulfide mounds, total of 1-2m high. Other chimneys are 5-6m high. Crinoids, sponges, and gorgonians (?) are the main bugs living on the chimneys.
1333 197 2680 Turned to follow the southern part of the axial ditch. Right now going through a heavily sedimented lobate flow, that in places are pillows. Only Chimlets occur here.
1340 191 The chimneys are down in a linear collapse that is maybe 4-5 m deep. Nature of this collapse is ambiguous. It looks there are selvages preserved in the wall of the collapse.
1342 202 big dead hydrothermal mounds with chimneys on top. The only outcrop is hydrothermal mud. Some of the chimneys are >10m high. The chimneys have bases 2-3m wide, but are >10m high. The view passes at least 5 chimneys/sulfides of this size.
1350 187 2675 Breccia of broken pillows and lobates. In the inner ditch of the graben, south of waypoint 6. Haven't seen chimneys for a couple of minutes.
1353 178 2677 Flat sedimented sheet or lobate flow. Plenty of sediment with a yellowish hydrothermal hue. The flat sheet flow. The flat sheet flow ends in a ridge of talus, and steep drop off. The statigraphy in the wall is mainly truncated pillows and lobates, but possibly some sheet flows? Here we find smaller chimneys again.
1359 109 2672 Crossing out of the inner ditch, and back into a heavily sedimented flat lava flow. This flow continues along this heading for 70-100m before dropping off along a scarp.
1402 The flow is really flat coming out of the inner ditch, but then turns into lobate lava flow, right about here.
1403 109 2670 A small field of little dead chimlets, on the top of a horst. On the base of the scarp is talus.
1404 106 Climbing back up over another horst. This horst is 8-9m high. Top of the horst is lobate lavas with hydrothermal sediment cover. The horst is 10-20m wide, before dropping off again. At the base of the horst walls are small talus ramps.
1408 108 2673 Flying at 17m, but just scraped over one of these horsts. Just going to come over another one of equal hieght. Almost all share features of lobate lavas with hydrothermal sediment coating on top, and talus ramps on either side.
1410 111 2667 Went over the top of a narrow ridge, 11m high, with no intact lava at all on the top. Its a rubble ridge.
1412 110 2661 In talus, we're now at the base of the eastern wall. Just going vertically up the wall and it's mostly talus. Talus blocks are 0.1-0.5m in height.
1415 124 Preparing to take Sample 11 from a ledge of scarp-ramp-scarp on the eastern side. Quite a bit of hydrothermal sediment.
1426 Underway after taking Sample 11, a piece of lobate lava from a ledge between two talus ramps on climbing up the east wall. X:2525 Y:3739
1428 110 2637 Trying to find the very top of the East wall. Just topping over a narrow rib of lava that looked like it was calving off the East fault scarp. The exposure of the walls in the rib was truncated pillow and lobate lavas
1432 118 2630 Reached the top of the East wall. It's mostly pillows and bulbous lobates. There are buds on the pillows, but the buds aren't glassy. Maybe they're some other type of encrustation.
1441 114 2631 Taking Sample 12, a piece of elongate pillow or bulbous lobate from the very top of the East wall of the graben. X:3031 Y:3077
1445 End of Dive 3354