IODP Expedition 379
Amundsen Sea West Antarctic Ice Sheet History
Daily Science Report for 19 March 2019
Location: Mardones Dock, Punta Arenas
Science Update: We continued with end of expedition and port call activities. This mostly consisted of submitting the final parts of the expedition summary, finalizing laboratory documentation and cleaning for the next expedition, and shipping (outgoing/incoming). Expedition 379 will officially end at 0800 h tomorrow (20 March).
Daily Science Report for 18 March 2019
Location: Mardones Dock, Punta Arenas
Science Update: We continued with end of expedition and port call activities. This mostly consisted of shipping (outgoing/incoming) as well as laboratory cleaning and documention to prepare for the next expedition.
Daily Science Report for 17 March 2019
Location: Mardones Dock, Punta Arenas
Science Update: We continued with end of expedition and port call activities. This included distributing incoming shipments and preparing the laboratories for the next expedition. Scientist laboratory teams have completed all shipboard reports.
Daily Science Report for 16 March 2019
Location: Mardones Dock, Punta Arenas
Science Update: We continued with end of expedition and port call activities. This included distributing incoming shipments, loading fresh produce, and preparing the laboratories for the next expedition (reporting, cleaning). Scientists continued to finalize remaining expedition reports and submitted revised postcruise research plans.
Daily Science Report for 15 March 2019
Location: Mardones Dock, Punta Arenas
Science Update: The departing surface shipments were prepared and staged for offloading. Incoming air shipments and three containers of surface freight were loaded. The last remaining data were acquired and the laboratories are being cleaned. Scientists continued to finalize Site U1533 reports and discuss postcruise research plans.
Daily Science Report for 14 March 2019
Location: In transit; Arrived Punta Arenas
Science Update: We continued our transit to Punta Arenas, Chile, entering the Strait of Magellan at 1115 h. After arriving at the Mardones Pier in Punta Arenas at 2000 h, immigration and customs formalities were completed. Scientists continued to finalize Site U1533 reports and discuss postcruise research plans.
Daily Science Report for 13 March 2019
Location:
• In Puerto Williams, Chile
• In transit to Punta Arenas
Science Update: We arrived in Puerto Williams and anchored at 0006 h. A variety of Chile officials (agent, immigration, port authority, police, and translator) boarded at 0020 h and departed at 0045 h. The helicopter for the medical evacuation landed on the ship at 0816 h and departed at 0838 h with the injured crew member. At 1009 h, we departed Puerto Williams and spent the rest of the day in transit to Punta Arenas. Scientists continued to work on Site U1533 reports and discuss postcruise research plans.
Daily Science Report for 12 March 2019
Location: In transit to Puerto Williams, Chile
Science Update: Today we travelled 178 nmi at an average speed of 13.7 nmi/h. After arriving at the Cape Horn pilot station, two pilots boarded at 1503 h and we continued toward Puerto Williams, Chile, to conduct a medical evacuation. Scientists continued to work on Site U1533 reports and discuss postcruise research plans.
Daily Science Report for 11 March 2019
Location: In transit to Puerto Williams, Chile
Science Update: Today we travelled 302 nmi at an average speed of 12.5 nmi/h. We are proceeding to Puerto Williams, Chile, to conduct a medical evacuation. We will then proceed to Punta Arenas, Chile. Scientists continued to work on Site U1533 reports and discuss postcruise research plans.
Daily Science Report for 10 March 2019
Location: In transit to Puerto Williams, Chile
Science Update: Today we travelled 296 nmi at an average speed of 12.3 nmi/h. We are proceeding to Puerto Williams, Chile, to conduct a medical evacuation. After that is complete, we will then proceed to Punta Arenas, Chile. Scientists continued to work on Site U1533 reports and discuss postcruise research plans.
Daily Science Report for 9 March 2019
Location: In transit to Chilean waters
Science Update: Today we completed 273 nmi of our 1358 nmi transit back to Chilean waters for a medevac at an average speed of 11.4 nmi/h. Scientists continued to work on Site U1533 reports and discuss postcruise research plans.
Daily Science Report for 8 March 2019
Location: In transit to Chilean waters
Science Update: Today we completed 247 nmi of the 1358 nmi transit to Chilean waters to evacuate an injured ship crew member. Scientists finished most remaining Hole U1533B analyses, met to present data collected this week and overall Site U1533 results, completed revisions to their Methods reports created earlier in the expedition, and continued group meetings to discuss postcruise research plans.
Daily Science Report for 7 March 2019
Location:
• Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
• In transit to Chilean waters
Science Update: We continued to wait for ice to clear the area with the bit 50 m above the seafloor until 0100 h. We then reentered Hole U1533B at 0155 h, retrieved the camera system, and started lowering the bit into the hole.
When the bit reached 324.6 m at 0315 h, we had to stop any further operations to return to Chilean waters to evacuate an injured ship crew member. After the camera system was back on board at 0430 h, we recovered the drill string, and the rig floor was secured for transit at 1330 h. We raised the thrusters and began the transit at 1448 h. We completed only 62 nmi of the transit due to poor visibility and ice in the area that limited our speed to 6.7 nmi/h.
Daily Science Report for 6 March 2019
Location: Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
Science Update: We continued to wait for ice to clear the area with the bit near the bottom of the hole. At 0315 h, we were finally able to recover Core 40R and resume coring. Cores 41R to 43R penetrated from 360.9 to 382.6 m. At 0930 h, approaching ice again forced us to raise the bit back up to 65.6 m below the seafloor. The ice kept approaching and we had to pull the bit completely out of Hole U1533B at 1115 h. With the bit 106 m above the seafloor, we installed the top drive, installed the core line, and recovered Core 43R at 1300 h. We then deployed the camera system at 1330 h so we would be ready to reenter Hole U1533B as soon as the ice would allow. While waiting for the ice to move away, we conducted a camera survey of the seafloor from 1845–2030 h and then waited the rest of the day with the bit 50 m above the seafloor. Today, Cores U1533B-40R to 43R penetrated from 351.3 to 382.6 m and recovered 9.23 m (29%).
Cores 39R–43R contain very dark greenish gray thinly laminated silty clay and greenish gray bioturbated diatom-rich mud. Dispersed sand and granules are present.
Daily Science Report for 5 March 2019
Location: Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
Science Update: After ice cleared the area at 0145 h, we lowered the bit from 65.6 m back down the hole. The bit encountered fill at 267.6 m, so we installed the top drive, and circulated/rotated the rest of the way. We resumed RCB coring from 316.0 m at 0415 h. Cores U1533B-36R to 38R then penetrated to 341.7 m before we had to stop coring again at 1130 h due to approaching ice. We raised the bit back up to 65.5 m, reinstalled the top drive, and recovered Core 38R at 1415 h.
At 1845 h, we were able to resume operations, so we lowered the bit back down the hole, installed the top drive when the bit was at 324.6 m, and circulated/rotated back to the bottom of the hole (341.7 m). We then cut Cores 39R–40R to 360.9 m. Before we could recover Core 40R, approaching ice forced us to pause operations again at 2315 h, and we spent the rest of the day waiting with the bit near the bottom of the hole. We didn’t install the core line to retrieve Core 40R as this would increase the time required to pull out of the hole if the ice kept approaching. Today, Cores U1533B-36R to 39R penetrated from 316.0 to 351.3 m and recovered 5.38 m (15%).
Cores U1533B-37R and 39X were X-rayed. Section 37R-CC was split and described; it contains 9 cm of heavily disturbed gray silty clay. Cores 36R and 38R had no recovery.
Daily Science Report for 4 March 2019
Location: Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
Science Update: Today we continued recovering the camera system and lowering the bit down into Hole U1533B. After the camera system was back aboard, we installed the top drive and circulated and rotated back to the bottom of the hole (283.9 m). We couldn’t start coring due to approaching ice, so we waited from 0315 to 0630 h for the ice to move away. Unfortunately, it kept converging on us, so we had to raise the bit back up to 66 m below the seafloor. At 1215 h, we resumed operations and lowered the bit back toward the bottom of the hole. The bit encountered resistance at 257.6 m and we had to drill back down to the bottom of the hole. At 1345 h, we started RCB coring from 283.9 m. Cores U1533B-32R to 35R then penetrated to 316.0 m but recovered only 0.07 m (0.2%). At 2245 h, we raised the bit back up to 65.5 m below the seafloor due to approaching ice.
Cores U1533B-32R and 34R had 0% recovery. Cores 33R and 35R were X-rayed and described. The material consists of three pebbles of igneous and metamorphic lithologies without matrix.
Daily Science Report for 3 March 2019
Location: Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
Science Update: We continued to retrieve the drill string after pulling out of Hole U1533B until 0820 h when the bit arrived back on the rig floor. Core 31X was recovered with the drill string. We prepared the RCB bottom-hole assembly and lowered it to the seafloor. After deploying the camera system and adjusting the bit depth to reenter Hole U1533B, approaching ice forced us to raise the bit back up to 70 m above the seafloor at 2045 h. We were cleared to reenter at 2215 h, and we reentered Hole U1533B at 2305 h. The rest of the day was spent recovering the camera system and lowering the bit into the hole.
Core 31X was split and described. It consisted of 28 cm of heavily disturbed dark greenish gray silty clay.
Daily Science Report for 2 March 2019
Location: Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
Science Update: After Cores U1533B-25X to 28X penetrated from 223.9 to 262.1 m, we had to stop operations at 0915 h due to approaching ice. We raised the bit back up to 50.6 m below seafloor and waited until 1315 h to resume operations. While lowering the bit back to the bottom of the hole, it encountered hard fill at 232.6 m. We installed the top drive, deployed an XCB core barrel with a center bit, and drilled back down to 262.1 m. After recovering the center bit, we resumed coring at 1645 h and Cores 29X–31X penetrated to 283.9 m. At 2145 h, we had to stop coring again due to approaching ice. Instead of waiting for the ice to leave the area to resume XCB coring, we decided to make use of this time to retrieve the drill string and switch to RCB coring. We pulled the bit out of the hole at 2303 h and continued to retrieve the drill string. At midnight, the bit was at 3877 m below the rig floor. Core 31X arrived on the rig floor with the bottom-hole assembly the following day. Today, Cores 23X–31X penetrated from 223.9 to 283.9 m and recovered 38.25 m (64%).
Cores U1533B-24X to 30X were X-rayed and Cores 26X to 29X were described. Lithologies include dark greenish gray diatom-bearing silty clay, interlaminated with gray silt, massive dark gray sandy diamictite and muddy conglomerate, and greenish gray muddy diatom ooze. Dispersed sand and gravel are present.
Daily Science Report for 1 March 2019
Location: Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
Science Update: After Core U1533B-20F (191.7–196.4 m) arrived on the rig floor at 0055 h, we had to stop coring due to approaching ice. At 0130 h, we raised the bit up to 165.6 m, removed the top drive, and continued pulling the bit up to 50.6 m below the seafloor. At 0600 h, we resumed operations, lowered the bit to the bottom of the hole, and resumed coring. After two half-length APC cores (21F–22F; 196.4–205.8 m), we decided to switch to XCB coring. Unfortunately, we had to stop operations again at 1115 h due to approaching ice. We raised the bit back up to 50.6 m below seafloor and waited until 1515 h to resume operations. We lowered the bit back to the bottom of the hole and Cores 23X–24X penetrated to 223.9 m by the end of the day. Today, Cores 20F to 24X penetrated from 191.7 to 223.9 m and recovered 25.2 m (78%).
Cores U1533B-20F to 23X were X-rayed and Cores U1533B-19F to 22F were described. The dominant lithologies are dark gray thinly laminated clay and silty clay and greenish gray bioturbated silty clay. A biosiliceous component is present in both lithologies. Silt and sand laminae are common, including ripple-laminated silt. Dispersed gravel is present.
Daily Science Report for 28 February 2019
Location:
• Hole U1533D (68°44.0727′S, 109°1.4901′W; water depth 4184 mbsl; proposed Site ASRE-09A)
• Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
Science Update: At 0645 h, the seas finally subsided enough for us to resume coring operations. Our preference was to reenter Hole U1533B and continue to deepen it; however, this required calmer seas because we didn’t want to risk the bit heaving down on the reentry funnel and damaging our ability to reenter. So, we offset the ship 15 m to the east of Hole U1533C and started APC coring from the seafloor at Hole U1533D. APC Cores U1533D-1H to 5H penetrated to 40 m and recovered 40.01 m (100%). As this was deep enough to provide overlap with the first cores of Hole U1533B and the swells had decreased, we terminated Hole U1533D at 1545 h. We moved back to Hole U1533B, deployed the camera system, and reentered at 1838 h. We recovered the camera system and lowered the bit toward the bottom of the hole. The bit encountered some resistance at 160 m, so we installed the top drive and rotated/circulated the remaining 27 m to the bottom of the hole (187.0 m). We resumed coring at 2215 h and Core U1533B-19F (187.0–191.7 m; 5.04 m recovered, 107%) arrived on the rig floor just before midnight.
Cores U1533D-1H to 5H and Cores U1533B-17H to 19F were X-rayed. Cores U1533B-17H to 18H and U1533D-1H to 5H were described. From 0 to 40 m, the lithologies include bioturbated diatom ooze and biosiliceous clay with laminae, color banding and mottling. From 168 to 187 m, the lithologies include dark greenish gray thinly laminated clay interbedded with bioturbated greenish gray silty clay; dispersed gravel is present and sand/silt laminae are common.
Daily Science Report for 27 February 2019
Location:
• Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
• Hole U1533C (68°44.0696′S, 109°1.5103′W; water depth 4183 mbsl; proposed Site ASRE-09A)
Science Update: We continued waiting for ice to clear the area with the bit at 50.6 m in Hole U1533B. At 0330 h we had to pull completely out of the hole due to approaching ice. Since the ice situation would not allow us to reenter Hole U1533B soon, we decided to make use of this time to take a few surficial APC cores. We offset the ship to a more ice-free portion of the seismic profile and adjusted the bit for a mudline core. As we prepared to shoot Core U1533C-1H at 0805 h, the core fired early due to significant ship heave. However, we recovered what appeared to be a good 7.7 m long mudline core. Before we could take any more cores, increasing ship heave forced us to stop operations at 0900 h. We raised the bit ~100 m above the seafloor and spent the rest of the day waiting for the swell to subside.
Core U1533C-1H was X-rayed and Cores U1533B-8H to 16H were described. The major lithology is dark greenish gray laminated silty clay interbedded with greenish gray biosiliceous silty clay and ooze, which occasionally contains a volcaniclastic component. Dispersed sand and gravel are present. Thin fine sand and silt beds, including some with normal grading, are also present.
Daily Science Report for 26 February 2019
Location: Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
Science Update: While retrieving Core U1533B-4H yesterday, we deployed the free-fall reentry system with two joints of 10.75 inch casing and then resumed APC coring. Today, APC coring continued until 0045 h (Core 7H to 82.5 m) when approaching ice caused us to pause operations and raise the bit up to 50.4 m below the seafloor. We resumed operations at 0230 h and Cores 8H to 12H penetrated to 130.0 m. After recovering Core 12H, approaching ice forced us to pause operations again at 1100 h, and the bit was raised back up to 50.6 m. At 1415 h, we lowered the bit back to the bottom of the hole and resumed APC coring. Cores 13H to 18H penetrated to 187.0 m before we had to pause operations again at 2330 h. As the day ended we were raising the bit toward the seafloor. Overall today, APC Cores U1533B-7H to 18H penetrated from 73.0 to 187.0 m and recovered 117.84 m (103%).
Cores U1533B-7H to 18H were X-rayed; Cores U1532A-2H to 3H and U1533B-2H to 7H were described. The sediments are highly variable and range from brown and gray moderately bioturbated color-banded and laminated silty clay to bioturbated greenish gray silty clay and muddy diatom ooze. Laminae and thin beds of silt, sand, or granule conglomerate are common and occasionally contain a volcaniclastic component. Rare dispersed pebbles are also present.
Daily Science Report for 25 February 2019
Location:
• Hole U1533A (68°44.0168′S, 109°0.6014′W; water depth 4181 mbsl; proposed Site ASRE-09A)
• Hole U1533B (68°44.0994′S, 109°3.0010′W; water depth 4179 mbsl; proposed Site ASRE-09A)
Science Update: After ice cleared the area at 0515 h, we adjusted the bit depth and started APC coring in Hole U1533A at 0640 h. We knew ice was approaching but wanted to use the limited time to get some surficial cores and penetrate deeply enough to deploy the free-fall reentry system. Cores U1533A-1H to 3H penetrated to 28.5 m and recovered 29.54 m (104%). Ice approached more quickly and directly than estimated and we had to pull out of Hole U1533A at 1045 h before we were able to deploy the reentry system.
At 1300 h, we were able to resume coring. We offset the ship ~1620 m to the west (264°) of Hole U1533A since the ice conditions would allow us to start operations sooner at this location. We started Hole U1533B at 1355 h and drilled without coring to 25.5 m. APC Cores U1533B-2H to 6H penetrated from 25.5 to 73.0 m and recovered 29.45 m (103%).
Cores U1533A-1H to 3H and U1533B-2H to 6H were X-rayed and Core U1533A-1H was described. The sediments consist of bioturbated diatom ooze, diatom-bearing mud, and silty clay. Dark mottling is common. Dispersed gravel and intervals of interlaminated silt and clay are also present.
Daily Science Report for 24 February 2019
Location: Hole U1533A (68°44.02′S, 109°00.60′W; water depth 4185 mbsl; proposed Site ASRE-09A)
Science Update: At 0330 h, we finished preparing a free-fall reentry system (free-fall funnel, mud skirt, and two joints of 10.75 inch casing) and centered it in the moonpool. We attached a different APC bit to the bottom-hole assembly and lowered it through the reentry system. This APC polycrystalline diamond compact (PDC) bit has a smaller outside diameter (9.875 inch) than our normal APC bits, so it can pass through the 10.75 inch casing. While lowering the bit to the seafloor, we had to stop for 2 h (0800–1000 h) to repair a line in the rig floor compressed air system. After the bit arrived at ~90 m above the seafloor at 1500 h, we had to pause operations due to approaching ice. At 1715 h, we installed the top drive and adjusted the bit to start coring; unfortunately, we had to stop operations again at 1930 h due to approaching ice. We spent the rest of the day waiting for ice to clear the area.
Daily Science Report for 23 February 2019
Location:
• Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
• Hole U1533A (68°44.02′S, 109°00.60′W; water depth 4210 mbsl; proposed Site ASRE-09A)
Science Update: The day started with raising the bit up to 64.5 m below the seafloor due to approaching ice. We continued waiting on the ice to clear the area until 0545 h, when the approaching ice forced us to pull the bit out of the hole. At 0630 h, we decided to stop further operations in Hole U1532G and started to recover the drill string. The bit arrived back on the rig floor at 1335 h and the rig floor was secured for transit at 1455 h. Before we could get underway, we had to maneuver the ship to get enough distance from the ice to have sufficient time to raise the thrusters. We started our transit to Site U1533 (proposed Site ASRE-09A) at 1615 h. After a ~31 nmi transit, we arrived at Site U1533 and switched to dynamic positioning at 2109 h. We spent the rest of the day on (a) conducting routine servicing of the drill line (slip and cut), (b) preparing the rig floor and moonpool for assembling a free-fall reentry system (free-fall funnel, mud skirt, and two joints of 10.75 inch casing), and (c) initial assembly of the reentry system.
Cores 46R–47R were described. The dominant lithology is dark greenish gray thinly laminated silty clay to greenish gray mud with dispersed clasts. Laminations are mostly planar and normal grading is common. Dispersed coarse sand grains are present in greenish gray intervals.
Daily Science Report for 22 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: Cores 40R to 45R penetrated from 726.8 to 779.9 m. Approaching ice forced us to stop cutting Core 45R after penetrating only 5.1 m. At 1315 h, we raised the bit up to 754.5 m and recovered Core 45R. We resumed operations at 1615 h, lowered the bit back to the bottom of the hole, and started coring at 1700 h. After Cores 46R–47R were recovered (779.9–794.0 m), we had to pause operations again from 2245–2400 h due to approaching ice. Today, Cores 40R–47R penetrated from 726.8 to 794.0 m and recovered 48.73 m (73%).
Cores U1532G-39R to 47R were X-rayed and Cores 39R to 45R were described. The dominant lithology is dark greenish gray thinly laminated silty clay with irregularly spaced intervals of greenish gray massive and bioturbated silty clay. Laminations are mostly planar and normal grading is common. Rare pebbles and soft sediment clasts are also present.
Daily Science Report for 21 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: We continued waiting on ice to clear the area with the bit at 64.5 m. At 0230 h, approaching ice forced us to pull the bit out of Hole U1532G so we could offset the ship. At 0630 h, we deployed the camera system in anticipation of being able to reenter Hole U1532G. After adjusting the bit depth for reentry at 0845 h, we surveyed the seafloor around Hole U1532G and then began attempts to reenter the hole. The free-fall funnel of the reentry system (with ~14 m of casing below) was not visible; it had settled substantially into the seafloor. After numerous attempts, we were finally able to reenter at 1225 h. After the camera system was recovered, we started lowering the bit back down to the bottom of the hole. At 1615 h, the bit encountered some resistance at 620.5 m, so we installed the top drive (so we could circulate and rotate), dropped a core barrel, and reamed back down to the bottom of the hole (717.3 m). We recovered the core barrel (Core U1532G-38G) at 2125 h and resumed RCB coring. Core 39R (717.3–726.8 m; 7.55 m recovered; 79%) arrived just before midnight.
Daily Science Report for 20 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: As soon as we finished cutting Core U1532G-37R at 0045 h, we had to raise the bit up to 54.5 m below seafloor due to approaching ice. Core 37R was finally recovered at 0420 h (707.7–717.3 m; 8.13 m recovered; 85%). We were cleared to resume coring at ~0655 h and started lowering the bit back down the hole. We installed the top drive when the bit encountered some resistance at 567.5 m, so we rotated and circulated back to 709.2 m. At that depth, we had to drop a center bit to redrill the ~8 m back to the bottom of the hole. At 1315 h, after circulating 25 barrels of mud to clean the cuttings out of the hole, approaching ice forced us to raise the bit back up to 64.5 m below the seafloor. We spent the rest of the day waiting for ice to clear the area.
Core U1532G-37R was X-rayed and Cores 33R–37R were described. The dominant lithology is dark gray planar laminated silty clay with intervals of interlaminated silt and clay. Beds of greenish gray bioturbated silty clay with variable sand and gravel content are also present. Normally graded laminae are common and thin carbonate-cemented sandstone beds are present.
Daily Science Report for 19 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: We continued RCB coring (Cores U1532G-28R to 34R) until 1445 h when we had to stop due to approaching ice. At 1930 h, we were able to resume coring and recovered Cores 35R–36R by end of the day. Overall today Cores 28R–36R penetrated from 621.5 to 707.7 m and recovered 75.14 m (87%).
Cores 27R to 36R were X-rayed and Cores 21R to 32R were described. The major lithology is dark gray silty clay with thin planar laminations interbedded with dark greenish gray bioturbated silty clay with dispersed sand and gravel. Thin beds of gray carbonate cemented silty sandstone are also present.
Daily Science Report for 18 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: Cores U1532G-15R to 27R penetrated from 506.7 to 621.5 m and recovered 103.66 m (90%). Cores 15R through 26R were X-rayed and Cores 15R through 20R were described. The sediments consist of dark greenish gray laminated silty clay and greenish gray bioturbated silty clay with sand and gravel. Clasts are common at the top of several greenish gray units. The dark greenish gray units contain planar, curved, normally graded, and lenticular laminations.
Daily Science Report for 17 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: After waiting for ice to clear the area until 1845 h, we lowered the bit from 65.0 to 467.5 m and resumed RCB coring at 2130 h. Core U1532G-15R (497.1–506.7 m; 8.31 m recovered; 87%) arrived at 2305 h and RCB coring continued.
Daily Science Report for 16 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: Cores U1532G-9R to 14R penetrated from 439.4 to 497.1 m (50.37 m recovered; 87%). After Core 14R arrived at 1315 h, approaching ice forced us to stop coring. We raised the bit up to 65 m below the seafloor and spent the rest of the day waiting for the ice to clear the area.
Cores U1532G-8R through 14R were X-rayed and Cores 6R–12R were split and described. The predominant sediment is thinly laminated dark greenish gray silty clay and massive greenish gray biosiliceous silty clay. Scattered gravel and sand are present. The laminated silty clay contains cemented silt laminae, silt lenses, and sediment intraclasts. The massive greenish gray units have irregular spacing with depth and variable thickness. Bioturbation is common.
Daily Science Report for 15 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: Today started with continued drilling without coring from 305.1 m in Hole U1532G. At 0345 h, we reached the depth where we wanted to start coring (372.3 m). After clearing ice from the wireline seal in the top drive and sinker bars, we recovered the RCB core barrel with the attached center bit and started RCB coring. After we recovered Cores U1532G-2R and 3R (to 391.4 m), approaching ice forced us to pause operations at 1100 h. We resumed coring at 1330 h and by midnight coring had reached 439.4 m. Overall today, Cores U1532G-2R to 8R penetrated from 372.3 to 439.4 m and recovered 64.52 m (96%).
Cores U1532G-2R to 7R were X-rayed and Cores 2R–5R were split and described. The sediments are dark gray thinly laminated silty clay with an interbed of greenish gray biosiliceous mud. The biosiliceous mud is heavily bioturbated, and dispersed sand and gravel are common.
Daily Science Report for 14 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31.5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: Today started with the bit at 55 m below the seafloor while monitoring approaching ice. At 0345 h, we had to pull completely out of the hole. At 0700 h, we adjusted the bit depth for reentry, deployed the subsea camera system, and reentered Hole U1532G at 1005 h. We recovered the camera system and started lowering the drill string. When the bit reached 201.5 m at 1345 h, we had to raise the bit back up to 45.5 m below seafloor due to approaching ice. After the rig floor was cleared to resume operations at 1630 h, we lowered the bit back down to the bottom of the hole and resumed drilling without coring to 305.1 m by the end of the day.
Daily Science Report for 13 February 2019
Location: Hole U1532G (68°36.6954′S, 107°31. 5299′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: At 0115 h, we completed assembling the free-fall reentry system and then started lowering the RCB drilling assembly through the middle of the reentry system and to the seafloor. After starting Hole U1532G at 0920 h and penetrating to 51.9 m, we dropped the reentry system at 1100 h. We continued drilling without coring to 161.5 m but had to pause operations due to approaching ice from 1730 to 1815 h. After spending ~1 h clearing ice from the wireline seal (BOP) in the top drive, we resumed drilling. When the bit had reached 171.2 m at 1945 h, approaching ice forced us to pause operations again and raise the bit back up to 54 m below the seafloor. We spent the rest of the day waiting for ice to clear the area.
Daily Science Report for 12 February 2019
Location:
• Hole U1532F (68°36.6833′S, 107°31.5303′W; water depth 3961 mbsl; proposed Site ASRE-08A)
• Hole U1532G (68°36.69′S, 107°31.53′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: After having to pull out of Hole U1532F yesterday due to ice, we continued waiting for ice to clear the area with the bit just above the seafloor. At 0900 h, we decided that due to the frequency of ice interruptions, a reentry system would be required for the multiple reentries needed to core deeply. We removed the top drive and recovered the drill string with the bit arriving back on the rig floor at 1845 h. While the drill string was being recovered, we started preparing the parts of a free-fall reentry system (casing shoe, one joint of casing, mud skirt, the outer structural parts of the hydraulic release tool, and free-fall funnel). As soon as the bit was back on board, we spent the rest of the day assembling the reentry system in the center of the moonpool beneath the rig floor.
Daily Science Report for 11 February 2019
Location: Hole U1532F (68°36.6833′S, 107°31.5303′W; water depth 3961 mbsl; proposed Site ASRE-08A)
Science Update: Late yesterday, we started drilling Hole U1532F with a plan to start RCB coring at ~378 m—just above the maximum coring depth reached in Hole U1532D. Today, we continued drilling Hole U1532F without coring from 18.6 to 105.1 m, at which point we had to stop to fix a hydraulic hose in the top drive (0230–0430 h). When the bit had reached 321.4 m (at 1630 h), approaching ice forced us to stop drilling, recover the RCB core barrel with center bit, and raise the bit back up to just below the seafloor (45.5 m). We wanted to deploy a free-fall funnel, but the ice was converging on our position too quickly and there was not enough time to deploy it. We pulled the bit out of seafloor at 1921 h and spent the rest of the day waiting for ice to clear the area.
Daily Science Report for 10 February 2019
Location:
• Hole U1532D (68°36.6953′S, 107°31.5015′W; water depth 3961.5 mbsl; proposed Site ASRE-08A)
• Hole U1532E (68°36.4852′S, 107°31.9608′W; water depth 3977.4 mbsl; proposed Site ASRE-08A)
• Hole U1532F (68°36.6833′S, 107°31.5303′W; water depth 3960.4 mbsl; proposed Site ASRE-08A)
Science Update: After waiting for ice, we deployed an RCB core barrel at 0000 h and started RCB coring in Hole U1532D. Cores U1532D-2R to 3R penetrated from 19.2 m (362.7–381.9 m) and recovered 17.42 m (91%). At 0415 h, approaching ice forced us to raise the bit back up to just below seafloor. The ice kept converging, so we pulled the bit completely out of Hole U1532D at 0605 h. Instead of waiting for the ice to pass and allow us to resume operations, we decided to move ~0.4 nmi to the northwest along the approved segment of the seismic reflection data and start a new hole. After waiting until 1130 h for ice to clear the area, we started drilling without coring in Hole U1532E, and the bit reached 101.6 m at 1445 h. Increasing winds, snow, and swell that made it difficult to visually track smaller pieces of ice (which do not show up on radar) combined with larger ice in the area made us pause operations and raise the bit up to just below the seafloor (48.6 m). Unfortunately, at 1830 h approaching ice forced us to pull the bit completely out of Hole U1532E. We raised the bit to 105 m above the seafloor, and while waiting for ice to move out of the area we conducted routine servicing of the drill line (slip and cut). We moved back near the location of Holes U1532A–U1532D and started drilling without coring in Hole U1532F at 2315 h. We plan to drill down to ~378 m and then RCB core from that depth.
Cores U1532D-2R through 3R were X-rayed manually as well as with the new automated system. These two cores consist of dark gray thinly laminated silty clay with one interbed of greenish gray silty clay with dispersed sand and granules.
Daily Science Report for 9 February 2019
Location: Hole U1532D (68°36.6953′S, 107°31.5015′W; water depth 3961.5 mbsl; proposed Site ASRE-08A)
Science Update: We continued drilling without coring in Hole U1532D from 78.8 to 247.2 m. At 0730 h, approaching ice forced us to raise the bit up to 55.5 m below the seafloor. The rig floor was cleared to resume operations at 1530 h and we lowered the bit back down to the bottom of the hole. At 1715 h, we dropped an RCB core barrel with a center bit and resumed drilling without coring from 247.2 m. At 2300 h, the bit reached 362.7 m and we started to recover the center bit to prepare for RCB coring.
The laboratory teams submitted their weekly reports and continued to acquire, process, and integrate results from Holes U1532A, U1532B, and U1532C.
Daily Science Report for 8 February 2019
Location: Hole U1532D (68°36.70′S, 107°31.47′W; water depth 3961.5 mbsl; proposed Site ASRE-08A)
Science Update: We finished recovering the drill string and APC/XCB bottom-hole assembly (BHA) with the bit arriving back on the rig floor at 0045 h. After laying out the APC/XCB specific parts of the BHA (seal bore and nonmagnetic drill collars), the drill crew started putting together the RCB BHA. Some extra time was required to fix a couple of issues identified by the routine verification of the drill collar interior diameter and core barrel space out within the BHA. From 0700 to 1430 h, we lowered the bit until it was 21.5 m above the seafloor. We then installed the top drive, deployed a center bit, and adjusted the drill string to prepare for starting Hole U1532D. Unfortunately, at 1545 h, we had to pause operations due to approaching ice. We maneuvered the ship as required to avoid the ice until it cleared the area. We were finally able to start drilling into the seafloor at 2130 h and drilled without coring from the seafloor to 74.8 m by the end of the day.
The laboratory teams presented a summary of their initial results from the first three holes at Site U1532.
Daily Science Report for 7 February 2019
Location: Hole U1532C (68°36.6952′S, 107°31.4721′W; water depth 3961.5 mbsl; proposed Site ASRE-08A)
Science Update: The first half of the day was spent XCB coring. Cores U1532C-28X to 33X penetrated from 338.8 to 392.3 m and recovered 45.19 m (85%). Approaching ice and diminishing visibility due to snow forced us to pause coring; Core 33X was pulled after penetrating 5.5 m. At this point, we decided to abandon further XCB coring and switch to RCB coring since (a) penetrating deeply at this is site is a primary objective and will require RCB coring, (b) RCB coring may get better quality core at the current hole depths, and (c) we wanted to take advantage of the time spent waiting for ice and environmental conditions to improve. We started recovering the drill string at 1315 h. The bit cleared the seafloor at 1520 h and we continued raising the drill string. The bottom-hole assembly (BHA) arrived at the rig floor by 2115 h and the rest of the day was spent modifying the BHA for RCB coring.
X-ray images were collected for Cores U1532C-28X to 33X, and Cores 27X to 33X were split and described. The sediments consist of relatively uniform dark gray thinly laminated silty clay with few irregularly spaced interbeds of greenish gray silty clay to sandy mud with dispersed granules and pebbles. Rare black laminae and lenses, some with a biosiliceous component, were found within the laminated silty clays.
Daily Science Report for 6 February 2019
Location: Hole U1532C (68°36.6952′S, 107°31.4721′W; water depth 3961.5 mbsl; proposed Site ASRE-08A)
Science Update: Just as Core U1532C-24X arrived on the rig floor at 2355 h last night, we had to stop coring again and raise the bit back up to 50.5 m due to approaching ice. At 0530 h this morning, we were able to resume operations and started lowering the bit back to the bottom of the hole. The bit encountered a bridge in the hole at 172.5 m, so we deployed an XCB core barrel with a center bit to drill through it and then washed the bit down to the bottom of the hole at 310.1 m. We circulated 25 barrels of mud to clean cuttings out of the hole and retrieved the center bit so we could resume XCB coring. Just as we were about to drop the XCB barrel, approaching ice put operations back on hold; however, this time we kept the bit near the bottom of the hole. At 1545 h, the ice moved away and we resumed XCB coring for the rest of the day. Today, Cores U1532C-25X to 27X penetrated from 310.1 to 338.8 m and recovered 25.36 m (88%).
X-ray images were collected for Cores U1532C-25X through 27X, and Cores U1532C-25X and -26X were split and described. The major lithology is thinly laminated, dark gray silty clay. Interbeds of greenish gray bioturbated and laminated mud with pebbles and granules occur, but are irregularly spaced with depth. Pebbles consist of both igneous and metamorphic lithologies, including vesicular basalt. Sand-sized olivine and green amphibole grains were identified in smear slides.
Daily Science Report for 5 February 2019
Location: Hole U1532C (68°36.6952′S, 107°31.4721′W; water depth 3961.5 mbsl; proposed Site ASRE-08A)
Science Update: The day started off with Cores U1532C-15F to 18F penetrating from 239.4 to 258.2 m (19.88 m recovered; 106%). We then switched to the extended core barrel (XCB) and Cores 19X to 22X penetrated from 258.2 to 291.0 m (10.18 m recovered; 31%); Cores 20X and 21X only recovered 6 cm. At 1445 h, as Core 22X arrived at the rig floor, approaching ice forced us to pause coring and raise the bit up to 50.5 m below the seafloor. We were able to resume operations at 1715 h. After lowering the bit back down to the bottom of the hole, we spent the rest of the day taking Cores 23X to 24X (291.0–310.1 m; 18.05 m recovered; 95%). Overall today, we penetrated 70.7 m and recovered 48.11 m (68%).
X-ray images were acquired for Cores U1532C-19X to 24X. Cores 11F to 23X were split and described. The major lithology is thinly laminated dark gray silty clay with interbeds of greenish gray massive and bioturbated mud with pebbles and granules. The biosiliceous component in greenish gray interbeds is highly variable. One rounded pebble (2.5 cm diameter) was identified as K-feldspar granite. For the XCB cores, slight to moderate drilling disturbance in the form of biscuits surrounded by drilling slurry is observed in the X-ray images and split cores.
Daily Science Report for 4 February 2019
Location: Hole U1532C (68°36.6952′S, 107°31.4721′W; water depth 3961.5 mbsl; proposed Site ASRE-08A)
Science Update: After pulling out of Hole U1532B at 1715 h yesterday due to approaching ice, we were finally able to resume operations shortly after midnight. The ship was offset 20 m South of Hole U1532B, and at 0035 h we started drilling into the seafloor at Hole U1532C. We drilled without coring from the seafloor, and at 0415 h we had reached 178.3 m. After retrieving the core barrel that was installed during drilling, we started Half-length APC (HLAPC) coring. Core U1532C-2F (178.3–183.0 m) arrived on deck at 0630 h. It was positioned to overlap with the deepest core from Hole U1532B (Core U1532B-11F; 175.6 to 180.3 m). Cores U1532C-2F to 11F (178.3–225.3 m) were recovered, but approaching ice forced us to pause coring at ~1630 h. The barrel for Core 12F had already been deployed and had to be recovered before we pulled the bit up to 61.9 m below the seafloor. We received the approval to lower the bit back down to the bottom of the hole at 1900 h, resumed coring, and took Cores 12F to 14F (225.3–239.4 m) by the end of the day. Cores U1532C-2F to 14F penetrated from 178.3 to 239.4 m and recovered 60.94 m (100%).
X-rays were collected on Cores U1532B-2F through 18F, and Cores U1532C-2F through 11F were split and described. The sediments are dark gray thinly laminated mud interbedded with greenish gray biosiliceous mud and ooze with pebbles and granules. The overall biogenic component in all sedimentary facies is elevated in Cores U1532C-6F through 9F. The uppermost carbonate-cemented sediment was observed in the top of Section U1532C-11F-1. HLAPC core disturbance was expressed as conjugate sets of reverse faults and upward displacement of the core edges, indicating brittle deformation and shortening perpendicular to the long axis of the core. Cores U1532B-11F and U1532C-2F contained sequences of identical lithological thickness and sedimentary properties, which confirmed successful overlap of Holes U1532B and U1532C.
Daily Science Report for 3 February 2019
Location: Hole U1532B (68°36.6837′S, 107°31.4696′W; water depth 3961.5 mbsl; proposed Site ASRE-08A)
Science Update: We continued APC coring and recovered Cores U1532B-5H to 9H (121.6–169.1 m; with a formation temperature measurement taken with Core 7H). After recovering Core 9H, approaching ice forced us to pause coring at 0600 h and raise the bit back up to 50.5 m below seafloor. We were able to resume operations at 0900 h, so we lowered the bit back to 169.1 m and resumed coring. Core U1352B-10H was a partial stroke, with the lowermost core liner deformed and a crack that extended up the entire core liner. Core 10H recovered 6.48 m, so we advanced the bit 6.5 m and switched to half-length APC (HLAPC) coring. After Core 11F (175.6–180.3 m) was recovered, approaching ice once again forced us to pause coring at 1315 h; we raised the bit back up to 50.5 m below seafloor. Unfortunately, the ice kept converging on our location, so we eventually had to pull the bit out of the hole at 1715 h. We spent the rest of the day positioning the ship as required to avoid the drifting ice. Cores U1532B-5H to 11H penetrated from 121.6 to 180.3 m and recovered 58.7 m (105%).
X-ray images were collected from Cores U1532B-7H through 11F, and Cores 5H through 11F were split and described. Starting with Core 8H the sediment became consolidated and splitting was done by saw. Drilling disturbance was observed at the top and base of all cores. Major lithologies consisted of dark gray laminated silty clay and light greenish gray silty clay with concentrations of granules and sand. A more significant biosiliceous component was observed in smear slides of both interbedded lithologies starting with Core 9H.
Daily Science Report for 2 February 2019
Location: Hole U1532B (68°36.6837′S, 107°31.4696′W; water depth 3961.5 mbsl; proposed Site ASRE-08A)
Science Update: We continued adjusting our position as required to maintain a safe distance from ice until 0015 h when the drill floor was cleared to resume operations. We offset the ship 20 m to the east of Hole U1532A, and started drilling in Hole U1532B at 0125 h. We drilled from the seafloor down to 93.1 m without coring, recovered the XCB core barrel, and resumed APC coring. The first core in Hole U1532B (Core U1532B-2H) arrived on the rig floor at 0415 h. While we were taking the next core (U1532B-3H), we had to pause coring again due to approaching ice. We raised the bit up to 50.5 m below the seafloor and waited for the ice to clear from 0800 to 1515 h. We then resumed APC coring and Core U1532B-4H (112.1–121.6 m; with a formation temperature measurement) arrived on deck at 1800 h. Before it was laid out on the rig floor, approaching ice forced us to stop coring again. We raised the bit back up to 50.5 m below the seafloor and waited from 1830 until 2215 h before being able to lower the bit back to the bottom of the hole and resume coring at 2300 h. Cores U1532B-2H to 4H penetrated from 93.1 to 121.6 m and recovered 30.14 m (106%).
Cores U1532A-8H through 11H and U1532B-2H through 6H were X-rayed. Cores U1532A-7H through 11H and Cores U1532B-2H through 4H were split and described. Equivalent lithological sequences between Cores U1532A-11H and U1532B-2H were noted, indicating that a successful overlap was achieved between the two holes. Cores U1532A-8H through 10H are dominated by brown laminated silty clays interbedded with massive gray silty clay containing granule and sand-sized clasts. Dark gray diatom-bearing mud intervals are present in the upper portion of Core U1532A-11H. The lower portion of Cores U1532A-11H and U1532B-2H through 4H are dominated by dark laminated gray silty clay with silt laminae and rare pebbles, with one interbed of greenish gray bioturbated silty clay with siliceous and calcareous biogenic components in Section U1532B-2H-6.
Daily Science Report for 1 February 2019
Location: Hole U1532A (68°36.68′S, 107°31.50′W, water depth 3961.5 mbsl; proposed Site ASRE-08A)
Science Update: Cores U1532A-7H to 11H penetrated from 53.1 to 100.6 m and recovered 47.86 m (101%). All APC cores were oriented and formation temperature measurements were made while taking Cores 7H (62.6 m) and 10H (91.1 m). After recovering Core 11H we had to stop coring at 0645 h due to a combination of approaching ice as well as increasing difficulty observing ice (due to fog/snow and a slight swell). We raised the bit up to 50 m below the seafloor with the intention of resuming coring in Hole U1532A after conditions improved. Instead, we had to pull out of the hole at 0930 h and raise the bit 100 m. We spent the rest of the day adjusting our position as required to maintain a safe distance from ice. After collecting X-ray images of Cores 3H through 7H to verify image quality and observe sedimentary structures, these cores were passed through the whole-round track systems. Cores U1532A-3H through 6H were split and described. The sediments consist of brown and olive silty clays with prominent foraminifer-bearing intervals down to Core 3H. Cores 4H–6H were characterized by interbedded olive brown to greenish gray silty clay and dark grayish brown clay with only rare biogenic components. Silt laminae and color banding were common. Rare pebbles, silt pockets, and dispersed sand grains were found in the silty clay intervals.