Alvin Dive 3356

February 16, 1999
Port Observer Eric C. Bergmanis

Starboard observer Ken Macdonald, Pilot Matt Heintz

Time Hdg Depth Description
08:48 1218 Starting Maggie spin.

08:53 1345 Completed 2.5 rotations for Maggie test.

09:38 257 2735 Bottom sighted

09:38 252 2755 ~60% of bottom obscured by sediment, 40% pillows and pillow fragments with considerable sediment on top obscuring details on pillow surfaces.

09:41 246 2756 ~70% smooth sediment cover, pillows and pillow fragments.
09:42 Stop 2758 Sample 1, Pillows age 3.5?

09:48 241 2744 Same sedimented pillow flow, few fractures and small fissures (few 10's of cm across) in surface. Striations visible on pillow but glass surface cannot be seen through sediment cover. A few fish and and anenomae are present.

09:50 241 2730 Passed over small scarp ~2m high (fault?) facing downslope. Here surface is >90% obscured by sediment, a few jumbly and folded curtain-like sheet flow surfaces can be seen poking through the sediment. Assuming that this is just a change in morphology, no age difference or flow contact is apparent.

09:52 234 2720 ~50 of surface obscured by sediment, primarily pillows in some places transitional to lobate flow. Some pillow heavily ornamented with pillow buds.

09:56 238 2707 Still ascending east-facing slope. On same kind of terrain, pillow flow with considerable sediment cover. Locally some pillows have a more tube-like morphology. Glass surface does not reflect our lights because of sediment.

09:58 238 2696 Here lava morphology more sheet flow than pillows. Passing over small fissure (<1m wide) with truncated pillow and lobate features in wall.

10:00 239 2690 Fissure ~30 cm wide, 2-3 m deep, features inside are somewhat obscured by sediment. ~60-70% of surface covered by sediment, sediment covered pillows poking through.

10:03 239 2680 Crossing ~10m scarp facing west, probably scarp we see on the DSL-120 record. Not a vertical scarp, but sloping to west.

10:05 246 2689 Crossing floor of depression, rocks completely obscured by sediment. A few marks or divits in the sediment visible, maybe biological activity making these marks?
10:07 244 2694 Very few rocks visible. Stopping on edge of small fissure trending N-S to sample. Either this surface is older than pillows on east facing slope, or maybe lava morpholgy so smooth that features do not show through sediment cover.

10:13 Stop 2695 Sample 2. We are in sediment cloud of our own creation while trying to sample. Almost 100% sediment cover, maybe sheet or lobate flows here.

10:19 256 2690 Passing over two fissures trending roughly N-S 0.5-1.0 m wide

10:22 125 2684 Have turned towards WP3, maybe went past WP2 about 50m. Crossing over floor of graben seen on sidescan survey. The surface here, although considerably sedimented, has pillows and more rarely lobate features poking through the sediment. Have crossed a few 0.5-1.0m wide fissures trending N-S.
Is this the mound we saw in DSL-120 record.

10:25 124 2693 Pillows age 3-3.5, poking through ~50% sediment cover. Pillows have striations and breadcrust form, but no glass reflecting through sediment.

10:28 122 2703 Surface here has greater relief locally so more lava is visible through sediment but overall age appears to be the same.

10:31 Stop 2720 Sample 3. Primarily sheet flows poking through heavy sediment cover.

10:36 254 2714 Turning to WP4. Mostly pillows, more rarely folded sheet flows with considerable sediment cover.

10:38 248 2717 ~80% sediment cover, lava visible are pillows and pillow fragments with striations but no glass reflecting. No major flow contacts discernible since landing, everything fairly old.

10:40 248 2713 Lobate transitional to sheet flows with lots of small collapses 0.5-2m across. Sediment cover as seen on the edge of collapses appears to be ~2cm thick.

10:41 249 2709 80-90% of surface obscured by sediment, some fractured pillows with buds poking through.

10:42 249 2707 Mixed bag of flow morphologies, pillows, lobates, some sheets. Dominant type appears to be pillows. Difficult to tell what flow morphology is like underneath sediment cover.

10:44 254 2698 Passing over area of fissures 1-3 meters wide, truncated features in walls, no apparent vertical offset. Flow morphology same as before, mostly pillows largely obscured by sediment.

10:45 250 2695 Loabte and sheet flows with collapses.

10:46 251 2695 Have passed over several small fissures trending roughly N-S

10:48 251 2689 Many small fissures in this area (0.2-2m wide) trending N-S. Lava morphology mostly pillows some heavily ornamented with buds.

10:52 253 2674 Most common form of life here is those ugly bulbous-headed fishes. Same terrain, mostly pillows with buds and much surface obscured by sediment.

10:53 251 2671 Passing over small fissure 20-30cm wide trending N-S. Zig-zag pattern in fractured surface.

10:59 251 2660 Passing over two fissures 1-3 m wide and then a talus slope at the base of a 5-6 m high east facing scarp almost vertical. A few meters on we come across another talus slope at the base of a east facing scarp of similar height. Step faults topped by sedimented pillows.

11:02 247 2636 Near the crest of east side of axial graben. Heavily sedimented age 3 pillows with buds cut by a few small fissures. ~30m away from WP4.

11:19 287 2630 Sample 5. Heavily sedimented terrain with very few pillows poking through.

11:20 289 2630 Few small collapses in surface of heavily sedimented lobate and pillow flow. Small fissure trending N-S

11:21 286 2634 Numerous collapses (as much as 2-3m wide, <0.5m deep) in surface of lobate flow. Rubble in bottom. Few pillows here heavily ornamented with buds.

11:23 287 2634 Piilows fractured, lobate collapses and fissures in this area reflect the tectonism that dominates this terrain.

11:24 286 2635 Large, deep collapse in surface of lobate flow, more like a collapsed lava lake feature.

11:25 287 2636 Flying over west facing scarp, probably the east wall of axial graben.

11:26 286 2643 Passing over another west facing scarp with much rubble and talus on slope.

11:30 290 2663 Descending into axial graben.

11:31 286 2676 Floor of axial graben covered with pillows that have distinctly less sediment than those seen on the east flank.

11:32 Stop 2678 Sample 6.




11:40 285 2677 Age 2 pillows with light dusting of sediment, many with pillow buds. Fissure here 2-3m wide. Very little biological activity here, just a few fishes.

11:41 283 2679 4-5m wide fissure several meters deep.

11:44 276 2674 Several fissures and collapse pits in surface of pillow and lobate flow on floor of axial graben.

11:48 274 2685 Extinct hydrothermal chimneys and much hydrothermal sediment covering flow here.

11:50 2679 Several meter high extinct hydrothermal chimney with mushroom-like critters on it.

11:51 275 2675 Ascending east facing wall after passing over several large fissures. Turns out to be a several meter high horst in floor of graben.

11:53 2666 Base of west wall of axial graben has talus slope, above that there are truncated pillow and lobate features in wall.

11:55 Stop 2668 Sample 7.

12:06 057 2687 Floor of axial graben characterized by fractured and fissured pillow lavas with considerable sediment cover. Appears older than young pillow flow first seen when entering axial graben from east side.

12:07 060 2690 3m wide fissure here. Horst and graben terrain in pillow flow.

12:09 060 2685 On lobate flow whose surface is 90% obscured by sediment.

12:11 060 2687 Extinct hydrothermal chimney and jumbly sheet flow surface.
Lava pillar 2m high and lobate and pillow fragments littering sloping surface.

12:17 065 2675 Sample 8, Lava pillar. Collapsed lobate surface, lots of plates and bathtub ringed walls of collapses.

12:19 073 2678 Pillow flows ornamented with buds cut by fissures. Sediment cover appears greater than seen on youngest flow on graben floor.

12:21 067 2686 Passing over fault 5-6m high upthrown on the east side. Non vertical surfaces littered with talus.

12:22 065 2679 Breadcrust textured pillows, moderate dusting of sediment.

12:24 068 2678 Pillow flow with small fissures, but not nearly as tectonized as surface near west wall of graben.

12:26 109 2675 Sample 9, Lobate fragment

12:31 320 2674 Extinct hydrothermal chimney directly below us.

12:33 321 2680 Passed through small "forest" of extinct chimneys. Lava surface is lobate with some sediment cover. Age 2.5

12:37 337 2683 Lobate flow with moderate sediment cover, a few small cracks and collapses in the surface.

12:40 336 2694 Pillow flow age 1.5

12:47 331 2684 Going past WP7 on same heading on age 1.5 pillow flow with light dusting of sediment. Many pillows are heavily ornamented with buds.

12:49 331 2683 Pillow and lobate flow with a few small cracks in the surface but no real collapses or fissures, appears relativley intact compared to other flows on graben floor.

12:50 333 2676 Climbing talus slope and then west wall of axial graben.

12:52 Stop 2668 Sample 11, lobate from west wall of axial graben

12:57 097 2674 Lobates with light dusting of sediment on axial graben floor, here cut by a fissure 30-40 cm wide.

13:01 Stop 2678 Sample 12, folded sheet flow from floor of graben.

13:07 101 2676 Jumbled and folded sheet flow cut locally by fissures 10-40 cm wide, but no big fissures or faults.

13:08 101 2681 Possibly have come across a contact, lobate flows cut by several fissures larger than on previous sheet flow, also sediment cover appears greater here than on sheet flow.

13:11 100 2686 Pillow and lobate flow with fissures appears older than sheet flow.

13:12 102 2685 Climbing talus slope on east wall of axial graben. Size of talus varies greatly, from meter size blocks to sand size grains.

13:24 128 2649 Passing through extinct hydrothermal area on east wall of axial graben. "Forest" of chimneys and lots of hydrothermal sediment. Continues to at least 2640m depth.

13:38 117 2633 Crested east wall of axial graben, crossing heavily sedimented sheet or lobate flow cut by several fissures ~1m wide.





13:40 113 2635 Pillows (age 3-3.5) poking through ~70% sediment cover. Pillows 2-3m across, some ornamented with buds. Flow locally transitional to lobate, numerous small collpases in surface.

13:48 008 2634 Traveling over lobate or sheet flow that appears as if it may have once been inflated and then settled. Heavily sedimented surface is broken into plates several meters across and there are numerous collapses ~1-2m wide and <0.5m deep.

13:50 015 2637 Folded curtain-like sheet flows poking through sediment.

13:51 016 2638 Lobate transitional to pillows, collapse pit 2-3m across with sedimented bottom.

14:07 008 2640 Lobate flow with numerous small collapses.

14:08 008 2639 Folded curtain sheet flow, in some places jumbled.

14:10 037 2640 On edge of collapse pit ~10 meters and 5 m deep, one wall of collapse pit is leaning towards the center of pit.

14:13 039 2638 Lobate transitional to sheet flow, we appear to have been on the same terrain since we crested the east wall.

14:14 037 2637 Heavily sedimented lobate and sheet flow.

14:18 Stop 2633 Sample 17

14:25 356 2636 Same terrain, lobate and pillow flow that appears to have deflated after emplacement.

14:28 034 2631 Large collapse pit on port side of sub. Several meters across, bottom filled with rubble. Maybe long wide fissure and not a collapse pit.

14:30 2631 Good fix: X 5390, Y 14209

14:31 2625 Weights away, end of dive.