IODP Expedition 393
South Atlantic Transect 2
Daily Science Report for 31 July 2022
Location: Underway to Cape Town
Science Update: The ship completed 267 nmi for a total of 315 nmi of the 1816 nmi voyage to Cape Town. Core description and sampling was completed in the Core Laboratory and sample analysis continues. The scientists met to discuss preparation for the two postexpedition sample parties.
Daily Science Report for 30 July 2022
Location:
• Hole U1560C (30°24.2005’S, 16°55.3703'W, water depth 3724.4 mbsl)
• Underway to Cape Town
Science Update: Cores U1560C-16F to 18X penetrated from 112.8 to 129.3 mbsf and recovered 10.83 m (66%). After Core U1560C-16F reached 117.5 mbsf we switched to the XCB coring system in anticipation of reaching basement at approximately the depth it was found in Hole U1560A, 120.2 mbsf. Basement was found at 129.0 mbsf in Hole U1560C, 9.8 m deeper than in Hole U1560A. The two holes are only 10 m lateral distance apart, and the difference in basement depth reflects the rugged basement surface topography that is typical of slow/intermediate spreading rate ridges. Core U1560B-17X drilled a further 0.3 m into the basement and recovered two ~5 cm pieces of basalt. It was the last core of the expedition. From 0530 h, the rig floor team coated the core line and then raised the bit to the ship, clearing the seafloor at 0900 h and the rig floor at 1655 h. The BHA was disassembled and stowed for transit and 115 ft of drill line was slipped and cut. We raised the thrusters and started the transit at 1930 h. The ship completed 48 nmi of the 1816 nmi voyage to Cape Town.
Cores U1560C-6H to 16X are middle to late Miocene nannofossil ooze with foraminifers and clay.
Daily Science Report for 29 July 2022
Location: Hole U1560C (30°24.2005′S, 16°55.3703′W, water depth 3724.4 mbsl)
Science Update: In preparation for coring, an XCB core barrel was deployed to close the lockable float valve in the BHA, which had been set open for the previous day’s downhole logging. The bit was set at 3721.7 mbsl and at 0245 h we started Hole U1560C. Core U1560C-1H recovered 6.5 m, placing the mudline depth at 3724.7 mbsf. Cores U1560C-1H to 15F penetrated from seafloor to 112.8 mbsf and recovered 111.9 m (101%). To correct the stratigraphic overlap with cores from Hole U1560A, cored in April 2021 on Expedition 395E, we drilled ahead by 2.0 m at 15 mbsf (drilled Interval U1560C-3-1). Advanced piston corer temperature (APCT-3) tool measurements were made on Cores U1560B-5H, 8H, and 11H. While taking the Core 11H APCT-3 measurement, the advanced piston corer (APC) core barrel became stuck in the formation, and it required three drillover attempts and 160,000 lb overpull to free it. The APC piston rods were damaged in the process and as a result we switched over to half-length APC coring from Core U1560C-12F.
Cores U1560C-1H to 5H are Pliocene–Pleistocene nannofossil ooze with foraminifers and clay.
Daily Science Report for 28 July 2022
Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: The triple combo downhole logging tool string reached the base of the hole, 316 mbsf, and completed one pass in the open hole (122 to 316 mbsf) and a second pass in the open hole and through casing to the seafloor. The triple combo was raised back to the ship and the FMS-sonic tool string was assembled. At 0645 h we started to lower it down the pipe. The bottom of the tool was kept 5 m off the bottom of the hole to prevent damage to the FMS caliper arms. The tool made two passes in the open hole. One of the caliper arms would not fully close after the second pass, remaining open by 0.2 inch and causing difficulty at first to bring the tool into the base of the BHA. However, we were able to bring the tool string to the surface without damage. We assembled the Ultrasonic Borehole Imager (UBI) tool string, and at 1545 h we lowered it down the pipe. This tool string also reached 311 mbsf and made two passes in the open hole, and was back on the rig floor at 2245 h. We rigged down the Schlumberger logging equipment and started pulling the bit out of Hole U1560B, clearing the seafloor at 2355 h.
Daily Science Report for 27 July 2022
Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: Having completed coring to 316.2 mbsf in Hole U1560B, we raised the bit to the ship, clearing the seafloor at 0225 h and the rig floor at 0905 h. The RCB bit, mechanical bit release, and RCB parts of the BHA were removed and replaced with an APC/XCB BHA. The RCB bit had been used for 42.5 drilling hours and had some wear to the inner teeth but was otherwise in reasonable condition. We replaced it with a polycrystalline diamond compact (PDC) bit for APC/XCB coring rather than the typical APC/XCB roller-cone bit because the narrower diameter of the PDC bit (9⅞ inch compared to 11 7⁄16 inch) allowed it to reenter casing at Hole U1560B for downhole logging. From 1115 h we lowered the bit to the seafloor and deployed the subsea camera to guide reentry. At 1755 h we reentered Hole U1560B and set the bit at 27.7 mbsf in the casing for downhole logging. From 2025 h we assembled the triple combo downhole logging tool string, consisting of magnetic susceptibility, electrical resistivity, density, neutron porosity, and natural gamma tools, and started lowering it down the pipe.
Core U1560B-31R contains a moderately plagioclase phyric sheet flow and Cores 32R to 39R contain sparsely to moderately plagioclase phyric pillow lavas. Cores 40R to 41R contain highly plagioclase olivine phyric sheet flows and sedimentary breccias.
Daily Science Report for 26 July 2022
Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: Cores U1560B-34R to 41R penetrated from 277.4 to 316.2 mbsf and recovered 13.9 m (36%). A 40-barrel mud sweep was run after each core to flush out any cuttings. At 2320 h, after Core U1560B-41R, we stopped coring to leave time for downhole logging in Hole U1560B and for coring an APC sediment hole at this site.
Core U1560B-27R contains aphyric lavas and Cores 28R to 30R contain moderately to sparsely plagioclase-olivine phyric pillow basalt.
Daily Science Report for 25 July 2022
Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: Cores U1560B-27R to 33R penetrated from 243.4 to 277.4 mbsf and recovered 14.0 m (41%). There have been no problems with torque and a 30-barrel mud sweep was run after every core to flush out any cuttings.
Cores U1560B-23R to 24R contain aphyric mixed pillow and sheet basalt lava flows. Cores U1560B-25R to 26R contain sparsely plagioclase-olivine phyric basalt pillow flows.
Daily Science Report for 24 July 2022
Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: One meter of soft fill was found when the new bit reached the bottom of Hole U1560B, and we restarted coring from 219.2 mbsf. Cores U1560B-22R to 26R penetrated from 219.2 to 243.4 mbsf and recovered 8.4 m (35%). Core U1560B-22R contains aphyric pillow lavas.
The science party and JRSO staff took part in a lifeboat drill, followed by group photographs on the bow of the ship.
Daily Science Report for 23 July 2022
Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: We started the day having stopped drilling in Hole U1560B at 219.2 mbsf in order to change to a new bit. While raising the bit out of Hole U1560B, there was 5,000–10,000 lb overpull at 128 mbsf. The drillers rotated through this area to clear the tight spot. We deployed the subsea camera to observe the BHA coming out of the reentry cone, and the bit cleared the seafloor at 0250 h. We raised the BHA to the ship and replaced the old bit with a new one. At 1030 h we started lowering the bit down to the seafloor. We redeployed the subsea camera and reentered Hole U1560B at 1955 h. By midnight the bit had reached 203.4 mbsf, passing the area of the previous tight spot without difficulty.
Core U1560B-21R contains aphyric pillow lavas.
Daily Science Report for 22 July 2022
Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: Cores U1560B-17R to 21R penetrated from 194.9 to 219.2 mbsf and recovered 13.9 m (57%). We ran a 60-barrel mud sweep after every core to flush out cuttings. The bit was cutting in-gauge good-recovery cores, but had been drilling for 53 h and would not last to the intended target depth, so at 2325 h we started to raise the pipe to change to a new bit.
Core U1560B-10R contains cryptocrystalline to microcrystalline aphyric to sparsely plagioclase-olivine-clinopyroxene phyric basalt pillow lavas. Cores U1560B-11R to 20R contain mostly microcrystalline aphyric pillow lavas.
The science party met to present and discuss the results from the Site U1583 basement cores.
Daily Science Report for 21 July 2022
Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: Cores U1560B-11R to 16R penetrated from 166.8 to 194.9 mbsf and recovered 7.2 m (26%). We ran a 60-barrel mud sweep after every core to flush out cuttings. Core U1560B-7R was empty and Cores U1560B-8R to 9R contain cryptocrystalline to microcrystalline aphyric to sparsely plagioclase-olivine-clinopyroxene phyric basalt pillow lavas.
Daily Science Report for 20 July 2022
Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: Cores U1560B-5R to 10R penetrated from 137.7 to 166.8 mbsf and recovered 9.36 m (32%). Sections U1560B-2R-1 to 3R-2 contain moderately plagioclase-olivine-pyroxene phyric basalt pillow lavas and interpillow sediment. Sections 3R-3 to 5R-1 contain sparsely plagioclase-olivine phyric basalt sheet flows and pillow lavas. Sections 5R-2 to 6R-3 contain a fine-grained sparsely plagioclase-olivine-clinopyroxene phyric basalt massive flow. The science party met to present and discuss the results from the Site U1583 sediment cores.
Daily Science Report for 19 July 2022
Location:
- Underway to Site U1560 (proposed Site SATL-25A)
- Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl)
Science Update: The ship completed the final 9 nmi of the 173 nmi voyage to Site U1560 (proposed Site SATL-25A). We lowered the thrusters and at 0130 h started operations at Hole U1560B, where casing and a reentry cone had previously been installed during Expedition 395E in April 2021. We assembled the RCB BHA and lowered it down to 3714 mbsl. Guided by the subsea camera images, we reentered Hole U1560B at 0920 h and lowered the bit down to 124 mbsf, the base of the existing hole. Although cement had been placed at the base of Hole U1560B during Expedition 395E, no cement was found by drilling. We started coring at 1215 h. Cores U1560B-2R to 4R penetrated hard rock from 124.0 to 137.7 mbsf and recovered 8.0 m (58%).
Daily Science Report for 18 July 2022
Location:
- Hole U1583F (30°42.6175′S, 20°26.0336′W, water depth 4210.0 mbsl)
- Underway to Site U1560 (proposed Site SATL-25A)
Science Update: After rigging down the downhole logging equipment on the rig floor, we raised the end of pipe from 102.8 mbsf, clearing seafloor at 0035 h. The BHA reached the ship at 0645 h and was disassembled. The rig floor was secured for transit by 0840 h, and we raised the thrusters and began the transit to Site U1560, completing 173 nmi of the total 182 nmi transit at an average speed of 11.4 kt.
Daily Science Report for 17 July 2022
Location: Hole U1583F (30°42.6175′S, 20°26.0336′W, water depth 4210.0 mbsl)
Science Update: We started the day preparing the triple combo downhole logging tool string (consisting of natural gamma radiation, neutron porosity, caliper, and electrical resistivity tools) for logging. We lowered the triple combo down Hole U1558F to 237 mbsf, within 3 m of the bottom, and made two logging passes in the open hole. While descending for the second pass, the tool string encountered an obstruction at 182 mbsf and could not pass below it. We raised the triple combo to the rig floor, disassembled it, and assembled the Formation MicroScanner (FMS)-sonic tool string. We lowered the FMS-sonic tool string down to 182 mbsf and made a logging pass up to the top of basement at 109.5 mbsf. At that point we found that the tool string could not go back down into basement, and overpull of approximately 8,000 lb was observed when trying to pull the tool string back into drill pipe. After pumping to attempt to remove a potential obstruction was unsuccessful, we rotated the pipe 180° and the tool string entered the pipe and was raised to the rig floor. By midnight we had disassembled the FMS-sonic tool string, ending downhole logging operations at Hole U1583F.
Daily Science Report for 16 July 2022
Location: Hole U1583F (30°42.6175′S, 20°26.0336′W, water depth 4210.0 mbsl)
Science Update: Cores U1583F-27R to 29R penetrated from 225.0 to 239.5 mbsf and recovered 1.36 m (9%). Core U1583F-29R reached 129.8 m into basement and was the last core from this hole. From 1230 h we ran a 75-barrel mud sweep, released the RCB bit at the bottom of the hole, and set the end of the pipe at 102.8 mbsf to prepare for wireline logging. At 1730 h we began to rig up the first logging tool string, consisting of natural gamma radiation, neutron porosity, caliper, and electrical resistivity tools. The tool string was lowered down the pipe but at 540 mbsl it developed an electrical fault and had to be raised back to the ship. By midnight the fault had been found in the electrical resistivity tool so we replaced it with the backup resistivity tool.
Cores U1583F-20R to 22R are moderately plagioclase-olivine phyric basalt. Core 23R contains sedimentary breccia and moderately to sparsely phyric basalt from the underlying unit. Cores 24R to 25R are moderately plagioclase-olivine-augite phyric basalt and Cores 26R to 29R are aphyric to sparsely plagioclase-olivine phyric basalt.
Daily Science Report for 15 July 2022
Location: Hole U1583F (30°42.6175′S, 20°26.0336′W, water depth 4210.0 mbsl)
Science Update: Cores U1583F-21R to 26R penetrated from 195.9 to 225.0 mbsf and recovered 5.46 m (19%). After each core there was backfill in the hole and the drill string experienced high torque at times while drilling. We ran a 60-barrel mud sweep after every core to flush out the cuttings. Core U1583F-16R contains 2 m of sedimentary breccia with clasts of angular pillow basalt and variably altered glass from the underlying unit in a limestone matrix. Cores U1583F-17R to 19R are moderately plagioclase phyric pillow lavas.
The science party met for a presentation on downhole logging.
Daily Science Report for 14 July 2022
Location: Hole U1583F (30°42.6175′S, 20°26.0336′W, water depth 4210.0 mbsl)
Science Update: Cores U1583F-16R to 20R penetrated from 171.6 to 195.9 mbsf and recovered 6.1 m (25%). After each core there was up to 3 m of backfill in the hole, and the drill string experienced high torque at times while drilling. We ran a 30-60-barrel mud sweep after every core to flush out the cuttings. Sections U1583F-13R-2 to 15R-1 are composed of pillow and ~1 m thick flows of aphyric microcrystalline basalt with ~0.2% each of plagioclase, olivine, and clinopyroxene phenocrysts.
Daily Science Report for 13 July 2022
Location: Hole U1583F (30°42.6175′S, 20°26.0336′W, water depth 4210.0 mbsl)
Science Update: Cores U1583F-11R to 15R penetrated from 148.4 to 171.6 mbsf and recovered 11.2 m (48%). Sections U1583F-10R-2 to U1583F-13R-1 are composed of aphyric microcrystalline basalt with ~0.2% each of plagioclase, olivine, and clinopyroxene phenocrysts.
Daily Science Report for 12 July 2022
Location: Hole U1583F (30°42.6175′S, 20°26.0336′W, water depth 4210.0 mbsl)
Science Update: Cores U1583F-6R to 10R penetrated from 128.9 to 148.4 mbsf and recovered 2.9 m (15%). Sections U1583F-5R-2 to U1583F-10R-1 are composed of moderately plagioclase-olivine phyric pillow lavas with rare clinopyroxene phenocrysts.
Daily Science Report for 11 July 2022
Location: Hole U1583F (30°42.6175′S, 20°26.0336′W, water depth 4210.0 mbsl)
Science Update: At 0030 h we started RCB Hole U1583F and washed down through most of the sediment column to 101 mbsf. Core U1583F-2R penetrated from 101.0 to 109.5 mbsf and recovered 6.4 m (76%) of clayey nannofossil ooze. The drillers contacted a hard formation at 109.7 mbsf. Cores U1583F-3R to 5R penetrated from 109.5 to 128.9 mbsf and recovered 12.3 m (63%). Sections U1583F-3R-1 to U1583F-5R-1 are composed of fine-grained holocrystalline basalt emplaced as a massive lava flow. Section U1583F-5R-2 is composed of moderately plagioclase-olivine phyric pillow lavas with rare clinopyroxene phenocrysts. The science party met to present and discuss the results from the Site U1558 basement cores.
Daily Science Report for 10 July 2022
Location: Hole U1583E (30°42.6285′S, 20°26.0340′W, water depth 4210.0 mbsl)
Science Update: We continued to raise the pipe from 414 mbsl and the bit reached the rig floor at 0435 h, ending Hole U1583E. The rig floor team then disassembled the lower part of the BHA and found that the APC core barrel assembly had stuck in the landing saver sub because a shear pin had become wedged between the landing seat and the core barrel. The APC cutting shoe was undamaged. Core U1583E-12H penetrated from 99.0 to 105.2 mbsf and recovered 6.13 m (99%). At 1000 h we began assembling the RCB BHA and then lowered it down to 4174 mbsl. From 2045 to midnight we slipped and cut the drill line, picked up the top drive, and prepared to start coring Hole U1583F.
Daily Science Report for 9 July 2022
Location: Hole U1583E (30°42.6285′S, 20°26.0340′W, water depth 4210.0 mbsl)
Science Update: We continued to raise the pipe from 2552 mbsl and found the Kinley wireline cutter and crimper in drill pipe Stand 83 with the bit at 2504 mbsl. The remaining core winch line was held in tension and a second Kinley cutter was deployed, but it did not cut the line. The rig floor team then resumed raising the pipe and had to cut the core winch line before removing each pipe stand. The second Kinley cutter was found in Stand 53 with the bit at 1703 mbsl. By midnight the bit had reached 414 mbsl.
The science party met to present and discuss the results from the Site U1558 sedimentary sequence.
Daily Science Report for 8 July 2022
Location: Hole U1583E (30°42.6285′S, 20°26.0340′W, water depth 4210.0 mbsl)
Science Update: Cores U1583E-3H to 11H penetrated from 13.5 to 99.5 mbsf and recovered 85.1 m (99%). After cutting Core U1583E-12H, the APC core barrel could not be pulled back into the drill pipe. From 1230 to 1545 h we tried to free the barrel by pumping and washing over it, but it would not move. From 1545 to 1730 h we rigged up and deployed the Kinley wireline cutter and crimper to cut the winch core line just above the APC corer. However, based on the core winch line tension, the Kinley wireline cutter and crimper had stopped before reaching the bottom of the drill string and cut part way down. Approximately 1560 m of core winch line was pulled up to the ship and we then started to raise pipe. By midnight, the bit had reached 2552 mbsl.
Daily Science Report for 7 July 2022
Location:
- Hole U1583C (30°42.6011′S, 20°26.0343′W, water depth 4214.6 mbsl)
- Hole U1583D (30°42.6288′S, 20°26.0340′W)
- Hole U1583E (30°42.6285′S, 20°26.0340′W, water depth 4210.0 mbsl)
Science Update: Cores U1583C-5H to 12H penetrated from 36.0 to 104.5 mbsf and recovered 72.0 m (105%). After retrieving Core U1583C-12H, the bit tagged a hard surface at 104.5 mbsf so we switched to XCB coring. Core U1583C-13X penetrated from 104.5 to 107.5 mbsf and recovered 1.9 m (63%) of diabase. At 1540 h we pulled the bit out of the hole, ending Hole U1583C. The ship was offset 20 m to the south of the Hole U1583C coordinates and we started Hole U1583D. Core U1583D-1H recovered 10.04 m and the mudline depth could not be determined. We raised the bit by 5 m and at 1835 h we started Hole U1583E and recovered a mudline at 4210.1 mbsl. Cores U1583E-1H to 2H penetrated from 0 to 13.5 mbsf and recovered 13.9 m (106%).
Cores U1583C-1H to 12H were described. Core 1H is clayey nannofossil ooze; Core 2H is brown clay with nannofossils; Cores 3H to 6H are nannofossil ooze with clay, and Cores 7H to 12H are clayey nannofossil ooze. Cores 3H to 12H are middle Miocene to early Oligocene in age.
Daily Science Report for 6 July 2022
Location:
- Underway to Site U1583 (proposed Site SATL-33B)
- Hole U1583A (30°42.6060′S, 20°26.0340′W)
- Hole U1583B (30°42.6062′S, 20°26.0341′W)
- Hole U1583C (30°42.6011′S, 20°26.0343′W, water depth 4214.6 mbsl)
Science Update: The ship completed the final 29 nmi of the 227 nmi voyage to Site U1583 (proposed Site SATL-33B). We lowered the thrusters and started operations at Site U1583 at 0315 h. On site, we noted a 41 m discrepancy between the precision depth recorder (PDR) 3.5 kHz depth estimate of 4234 mbsl and the prospectus seafloor depth estimate of 4193 mbsl. Ship heave was 3–4 m. The APC/XCB BHA was made up and lowered down to 4229 mbsl, 5 m above the PDR estimated depth. At 1545 h we started Hole U1583A; Core U1583A-1H recovered 9.14 m and the mudline depth could not be determined. At 1715 h we started Hole U1583B with the drill bit 5 m shallower; Core U1583B-1H recovered 9.38 m and the mudline depth again could not be determined. We moved 10 m to the north, pulled the bit up 10 m shallower to 4214 mbsl, and at 1845 h we started Hole U1583C and recovered a mudline at 4214.6 mbsl. Cores U1583C-1R to 4R penetrated from 0 to 36.0 mbsf and recovered 36.3 m (101%).
Daily Science Report for 5 July 2022
Location:
- Hole U1558D (30°53.7814′S, 24°50.4822′W, water depth 4334 mbsl)
- Underway to Site U1583 (proposed Site SATL-33B)
Science Update: From midnight to 0330 h we disassembled the BHA and examined it for damage following yesterday’s operations to free the BHA from the casing, and we set aside the bottom three drill collars, one of which was slightly bent. We then secured the rig floor for transit and raised the thrusters, ending operations at Hole U1558D and Site U1558. We started the transit to Site U1583 (proposed Site SATL-33B) at 0530 h and by midnight the ship had completed 198 nmi of the 227 nmi voyage.
Cores U1558D-29R to 39R were described. They are sparsely to moderately plagioclase-olivine-phyric basalt, emplaced as pillow lavas with occasional sheeted flows, apart from a >3 m massive flow in Core 37R. Mottled to variolitic textures are more common than in the overlying basalts. There are occasional hyaloclastite-basalt clast interflow breccias.
Daily Science Report for 4 July 2022
Location: Hole U1558D (30°53.7814′S, 24°50.4822′W, water depth 4334 mbsl)
Science Update: Core U1558D-39R penetrated from 365.4 to 370.2 mbsf and recovered 2.6 m (54%). This core reached 203.4 m into basement to meet our 200 m basement target depth for this site. At 0330 h we set back the top drive and pulled the bit up to 126.3 mbsf, observing 20,000 lb drag. At 0445 h we deployed the subsea camera to observe the bit release and guide reentry, in preparation for downhole logging. We pulled the bit out of the hole to 4317 mbsl, 17 m above seafloor. However, at 0615 h the drill pipe was observed by the subsea camera to be still inside the reentry cone, with the cone much higher up than it should be. The extra weight on the drill string confirmed that the cone and casing had been pulled out of the hole by the BHA. From 0730 to 0830 h we attempted unsuccessfully to free the casing by pushing into the seafloor. We brought the camera back up to the ship and from 1030 to 1100 h we attempted to free the drill string from the casing by rotation. A weight decrease of 30,000 lb was observed on the hook load indicator. The subsea camera was deployed again and at 1345 h we observed that the cone had fallen away and that some of the BHA drill collars appeared to be bent. We then pulled the camera and bit back up to the ship. By midnight the bit was at 449.5 mbsl.
Cores U1558D-22R to 28R were split and described. They contain sparsely plagiolcase phyric basalt with rare olivine and clinopyroxene phenocrysts.
Daily Science Report for 3 July 2022
Location: Hole U1558D (30°53.7814′S, 24°50.4822′W, water depth 4334 mbsl)
Science Update: Cores U1558D-31R to 38R penetrated from 326.6 to 365.4 mbsf and recovered 16.3 m (42%). Cores U1558D-15R to 21R were split and described. They contain sparsely plagioclase-olivine-phyric pillow lavas. The science party worked on writing their results on the sediment sequence cored in Hole U1558F for the site report.
Daily Science Report for 2 July 2022
Location: Hole U1558D (30°53.7814′S, 24°50.4822′W, water depth 4334 mbsl)
Science Update: Cores U1558D-22R to 30R penetrated from 282.9 to 326.6 mbsf and recovered 13.1 m (30%). Cores U1558D-12R to 15R were split and described. Core 12R contains moderately to highly plagioclase-olivine-clinopyroxene-phyric basalt pillow lavas. Section 13R-1 contains volcaniclastic breccia of broken pillow lavas and altered glass in a sediment matrix. Sections 13R-2 to 14R-2 are sparsely plagioclase-olivine-phyric pillow lavas with interpillow sediment and breccia. Core 15R contains the same basalt as the overlying unit but without interpillow sediment.
Daily Science Report for 1 July 2022
Location: Hole U1558D (30°53.7814′S, 24°50.4822′W, water depth 4334 mbsl)
Science Update: Cores U1558D-15R to 21R penetrated from 244.1 to 282.9 mbsf and recovered 18.1 m (47%). Cores U1558D-8R to 11R were split and described. They are moderately plagioclase-olivine-clinopyroxene-phyric basaltic lavas, slightly to moderately altered.