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IODP Expedition 398

Hellenic Arc Volcanic Field

Daily Science Report for 31 January 2023

Location: Hole U1599C (proposed Site CSK-23A); 36°26.9389′N, 25°46.7762′E; water depth 592.7 m

Science Update: The drill ahead without recovery continued from 126.7 to 223.0 mbsf. Cores U1599C-2R to 14R were retrieved from 223.0 to 348.8 mbsf. The average recovery for today’s cored interval is 66% (0%–102%).

Cores U1599C-2R to 13R were run through the whole-round physical properties track systems. Cores U1599C-2R to 11R were split and described. The cores consist of nannofossil ooze, organic-rich ooze, calcareous mud, ash, dolomitic marl, organic-rich marl, and marl. Microscopic analyses showed transparent glass, authigenic dolomite, and calcareous nannofossils.

Daily Science Report for 30 January 2023

Locations:

  • Hole U1600B (proposed Site CSK-24A); 36°32.6092′N, 25°39.0311′E; water depth 326.3 m
  • Hole U1599C (proposed Site CSK-23A); 36°26.9389′N, 25°46.7762′E; water depth 592.7 m

Science Update: Cores U1600B-7F to 19F were retrieved from 30.3 to 91.4 mbsf, the final depth of the hole. The drill string was tripped out of the hole, the rig floor was secured, and the vessel started its 18.4 nmi sea passage toward Santorini at 1000 h, ending Hole U1600B. Hole U1600B reached a maximum penetration of 91.4 mbsf with a cored interval of 91.4 m and a recovery of 66.67 m. The average recovery for the hole was 75%. The vessel was on location and under DP control in the northern caldera at 1200 h. A launch pulled up alongside, two persons (1 scientist, 1 crewmember) boarded, and two pallets of fresh fruits and vegetables arrived at 1215 h. The 24.6 nmi sea passage to Site U1599 began at 1242 h. The vessel was on location 50 m southwest of Hole U1599A and under DP control at 1520 h. Hole U1599C was spudded at 1925 h in a water depth of 592.7 mbsf (by offset). At midnight, the hole was drilled without recovery to a depth of 126.7 mbsf.

Cores U1600B-5F to 19F were run through the whole-round physical properties track systems. Cores U1600A-9F to 10F and U1600B-1H to 19F were split and described. The cores consist of ash, lithic ash, gravel, lapilli ash, lapilli, lithic lapilli, muddy ash, bioclastic sand, bioclastic ash, bioclastic lapilli, calcareous sand, and calcareous tuffaceous sand. Microscopic analyses showed transparent and brown glass, volcanic lithics, authigenic calcite, calcareous nannofossils, foraminifers, diatoms, radiolarians, shell fragments, and sponge spicules.

Daily Science Report for 29 January 2023

Locations:

  • Hole U1599B (proposed Site CSK-23A); 36°26.9764′N, 25°46.8237′E; water depth 592.7 m
  • Hole U1600A (proposed Site CSK-24A); 36°32.6277′N, 25°39.0553′E; water depth 326.2 m
  • Hole U1600B (proposed Site CSK-24A); 36°32.6092′N, 25°39.0311′E; water depth 326.3 m

Science Update: The trip out of Hole U1599B continued until 0100 h, when the bit cleared the seafloor. The 8.4 nmi passage to Site U1600 (proposed Site CSK-24A) began at 0336 h, ending Site U1599. The vessel arrived on location at 0430 h and was under DP control at 0450 h. Hole U1600A was spudded at 0710 h with Core U1600A-1H recovering 4.0 m, establishing the seafloor depth at 326.2 mbsl. Cores U1600A-2H to 4H were retrieved from 4.0 to 32.5 mbsf. A 45,000 lb overpull was observed. The decision was made to switch to HLAPC with Cores 5F to 10F at 60.6 mbsf. Coring was switched to the XCB with Cores 11X to 13X at 84.4 mbsf, the final depth for this hole. Hole U1600A reached a maximum penetration of 84.4 mbsf with a cored interval of 84.4 m and a recovery of 51.71 m. The average recovery for the hole was 61%. The vessel was moved 50 m southwest of Hole U1600A. Hole U1600B was spudded at 2005 h with Core U1600B-1H recovering 6.8 m, establishing seafloor depth at 326.3 mbsl. Switching to HLAPC, Cores U1600B-2F to 6F were retrieved from 6.8 to 30.3 mbsf. The average recovery for today’s cored interval is 93% (78%–100%).

Cores U1599B-21F to 40F, U1600A-1H to 10F, and U1600B-1H to 4F were run through the whole-round physical properties track systems. Cores U1599B-12F to 40F and U1600A-1H to 8F were split and described. The cores consist of nannofossil ooze, tuffaceous ooze, organic-rich ooze, ash, lithic ash, gravel, lapilli ash, lapilli, lithic lapilli, muddy ash, bioclastic sand, calcareous sand, and calcareous tuffaceous sand. Microscopic analyses showed transparent and brown glass, volcanic lithics, authigenic calcite, calcareous nannofossils, foraminifers, diatoms, radiolarians, shell fragments, and sponge spicules.

Daily Science Report for 28 January 2023

Location: Hole U1599B (proposed Site CSK-24A); 36°26.9764′N, 25°46.8237′E; water depth 592.7 m

Science Update: Cores U1599B-2H to 11H were retrieved from 9.7 to 104.7 mbsf. The HLAPC was deployed starting at Core 12F and continued to Core 40F. After reaching 241 mbsf, the drillers began tripping the pipe out of Hole U1599B. Hole U1599B reached a maximum penetration of 241 mbsf with a cored interval of 241 m and a recovery of 199.13 m. The average recovery for the hole was 83%.

Cores U1599A-42F to 44F and U1599B-2H to 20F were run through the whole-round physical properties track systems. Cores U1599A-34F to 44F and U1599B-2H to 11H were split and described. The cores consist of nannofossil ooze, tuffaceous ooze, organic-rich ooze, ash, gravel, calcareous tuffaceous mud, lapilli, lithic crystal lapilli, and gravelly sandstone with shells. Microscopic analyses showed transparent and brown glass, authigenic calcite, calcareous nannofossils, foraminifers, diatoms, radiolaria, and sponge spicules.

Daily Science Report for 27 January 2023

Locations:

  • Hole U1599A (proposed Site CSK-24A); 36°26.9592′N, 25°46.8005′E; water depth 591.2 m
  • Hole U1599B (proposed Site CSK-24A); 36°26.9764′N, 25°46.8237′E; water depth 592.7 m

Science Update: Cores U1599A-14F to 44F were retrieved from 99.7 to 245.4 mbsf, the final depth of this hole. The core barrel got stuck during Core U1599A-44F and was freed by a combination of drilling over and an overpull of 100,000 lb. Hole U1599A reached a maximum penetration of 245.4 mbsf with a cored interval of 245.4 m and a recovery of 204.57 m. The average recovery for the hole was 83%. The vessel was moved 50 m northeast, and Hole U1599B was spudded at 2330 h with Core U1599B-1X. The bit tagged the seafloor at a depth of 592.7 mbsl. Core U1599B-1X had no recovery.

Cores U1599A-7H to 41F were run through the whole-round physical properties track systems. Cores U1599A-5H to 33F were split and described. The cores consist of nannofossil ooze, tuffaceous ooze, organic-rich ooze, organic-rich tuffaceous ooze, ash, lithic ash, lapilli ash, breccia, and lithic crystal ash. Microscopic analyses showed transparent and brown glass, volcanic lithics, authigenic pyrite and calcite, calcareous nannofossils, foraminifers, diatoms, and sponge spicules.

Daily Science Report for 26 January 2023

Location: Hole U1599A (proposed Site CSK-23A); 36°26.9592′N, 25°46.8005′E; water depth 591.2 m

Science Update: The ship waited on station for approval from the Greek government to conduct operations. At 1315 h, the vessel resumed operations. The first two attempts to spud Hole U1599A resulted in broken APC barrels. The decision was made to spud the hole with the XCB barrel at 1535 h. Core U1599A-1X had no recovery. The bit tagged the seafloor at a depth of 591.2 mbsl. Cores U1599A-2F to 13F were retrieved from 9.7 to 99.7 mbsf, using a combination of APC and HLAPC coring. The average recovery for today’s cored interval is 83% (0%–107%).

Cores U1599A-2F to 7H were run through the whole-round physical properties track systems. Cores U1598A-2F to 4H were split and described. The cores consist of bioclastic gravelly muddy sand, muddy sand, nannofossil ooze, organic-rich ooze, tuffaceous ooze, ash, lithic crystal ash, and lapilli ash. Microscopic analyses showed medium amounts of transparent glass, authigenic calcite, calcareous nannofossils, and sponge spicules.

Daily Science Report for 25 January 2023

Locations:

  • Hole 1598A (proposed Site CSK-14A) 36°18.2937′N, 25°7.7155′E, water depth 521.5 m
  • Hole 1598B (proposed Site CSK-14A) 36°18.2747′N, 25°7.6929′E, water depth 521.5 m
  • Site U1599 (proposed Site CSK-24A) 36°26.958′N, 25°46.800′E

Science Update: Cores U1598A-2H to 10F were retrieved from 3.7 to 79.6 mbsf, the final depth for this hole. Excessive torque was observed after Core U1598A-10F, indicating a collapsing hole. The drill string was pulled out of the hole and the hole was ended at 0715 h. Hole U1598A reached a maximum penetration of 79.6 mbsf with a cored interval of 79.6 m and a recovery of 54.5 m. The average recovery for the hole was 68%. The vessel was offset 50 m southwest, and Hole U1598B was spudded at 0805 h and drilled without recovery to 75.6 mbsf. Cores U1598B-2F to 6F were retrieved from 75.6 to 98.8 mbsf, the final depth for this hole. Hole U1598B reached a maximum penetration of 98.8 mbsf with a cored interval of 23.5 m and a recovery of 7.91 m. The average recovery for the hole was 34%. Excessive torque was observed after Core U1598B-6F, indicating a collapsing hole. The drill string was pulled out of the hole and the site was ended at 1430 h. The sea passage to Site U1599 began at 1730 h, ending Site U1598. The vessel completed the 33 nmi passage in 3.6 h, arriving on site at 2050 h.

Cores U1598A-1H to 10F and U1598B-2F to 6F were run through the whole-round physical properties track systems. Cores U1598A-1H to 10 and U1598B-2F to 6F were split and described. The cores consist of calcareous mud, organic-rich calcareous mud, tuffaceous mud, ash, lapilli-ash, pumice lapilli, lithic lapilli, nannofossil ooze, tuffaceous ooze, and organic-rich ooze.

Daily Science Report for 24 January 2023

Locations:

  • Hole U1596A (proposed Site CSK-06B); 36°26.5378′N, 25°22.5130′E; water depth 382.0 m
  • Hole U1597A (proposed Site CSK-05C); 36°26.2494′N, 25°22.7326′E, water depth 382.3 m
  • Hole U1598A (proposed Site CSK-14A) 36°18.2937′N, 25°7.7155′E, water depth 521.5 m

Science Update: Hole U1596A was spudded at 0650 h with Core U1596A-1H recovering 3.9 m, establishing seafloor depth at 382.0 mbsl. Cores U1596A-2H to 5H were retrieved from 3.9 to 41.9 mbsf, the final depth for this hole. Excessive torque was observed before shooting Core 6H, indicating a collapsing hole. The drill string was pulled out of the hole and the site was ended at 1100 h. Hole U1596A reached a maximum penetration of 41.9 mbsf with a cored interval of 41.9 m and a recovery of 38.0 m. The average recovery for the hole was 91%. The vessel was offset 0.34 nmi with the DP system, arriving at Site U1597 at 1136 h. Hole U1597A was spudded at 1240 h with Core U1597A-1H recovering 5.6 m, establishing seafloor depth at 382.3 mbsl. Cores U1597A-2H to 5H were retrieved from 5.6 to 43.6 mbsf, the final depth for this hole. Hole U1597A reached a maximum penetration of 43.6 mbsf with a cored interval of 43.6 m and a recovery of 40.8 m. The average recovery for the hole was 94%. The drill string was tripped out of the hole and the bit cleared the rotary table at 1728 h. The 15 nmi sea passage to Site U1598 began at 1824 h, ending Site U1597. The vessel completed the passage in 1.8 h at 1950 h. Hole U1598A was spudded at 2350 h with Core U1598A-1H recovering 3.7 m, establishing the seafloor depth at 521.5 mbsl.

Cores U1595A-11H, U1596A-1H to 5H, and U1597A-1H to 5H were run through the whole-round physical properties track systems. Cores U1595A-4H to 10H, U1596A-1H to 5H, and U1597A-1H to 5H were split and described. The cores consist of mud, tuffaceous mud, ash, lapilli, and lapilli-ash with coarse pumice. Microscopic analyses showed transparent and brown glass, volcanic lithics, authigenic calcite, iron and manganese oxides, calcareous nannofossils, foraminifera, and sponge spicules.

Daily Science Report for 23 January 2023

Locations:

  • Hole U1594A (proposed Site CSK-07B); 36°23.3368′N, 25°25.0290′E; water depth 291.0 m
  • Hole U1595A (proposed Site CSK-08B); 36°22.8955′N, 25°24.3630′E, water depth 291.58 m
  • Moving to Site U1596 (proposed Site CSK-06B); midnight position: 36°23.800′N, 25°24.800′E

Science Update: Cores U1594A-2H to 6H were retrieved from 4.2 to 51.7 mbsf, the final depth for this hole. The driller observed tight hole conditions after Core 6H and worked the drill string for several hours. The bit cleared the seafloor at 0350 h, ending Site U1594. Hole U1594A reached a maximum penetration of 51.7 mbsf with a cored interval of 51.7 m and a recovery of 47.94 m. The average recovery for the hole was 93%. The vessel was offset 0.7 nmi with the DP system. Hole U1595A was spudded at 0635 h with Core U1595A-1H and a recovery of 3.6 m, establishing seafloor depth at 291.58 mbsl. Cores U1595A-2H to 11H were retrieved from 3.6 to 98.6 mbsf, the final depth for this hole. The hole suddenly started to collapse after Core 11H. The driller was able to work the drill string free after 3 h. The bit cleared the seafloor at 1636 h. Following a maintenance period on the top drive, the sea passage to Site U1596 began at 2300 h, ending Site U1595. Hole U1595A reached a maximum penetration of 98.6 mbsf with a cored interval of 98.6 m and a recovery of 72.3 m. The average recovery for the hole was 73%.

Cores U1594A-1H to 6H and U1595A-1H to 10H were run through the whole-round physical properties track systems. Cores U1594A-1H to 6H and U1595A-1H to 3H were split and described. The cores consist of mud, tuffaceous mud, ash, lapilli, and lapilli-ash with coarse pumice. Microscopic analyses showed transparent and brown glass, volcanic lithics, authigenic calcite, iron and manganese oxides, calcareous nannofossils, foraminifera, and sponge spicules.

Daily Science Report for 22 January 2023

Locations:

  • Hole U1593C (proposed Site CSK-04C); 36°34.506′N, 25°24.8995′E; water depth 404.0 m
  • Hole U1594A (proposed Site CSK-07B); 36°23.3368‘N, 25°25.0290‘E; water depth 291.0 m

Science Update: Following the drilled interval to 192.6 mbsf, the center bit was removed for coring. High torque on the drill string was observed. The driller worked the stuck pipe for several hours without success. The pipe was severed at 37 mbsf at 0930 h. The drill string was tripped up to the vessel and cleared the rotary table at 1320 h. Hole U1593C ended without recovery. The 15 nmi sea passage to Site U1594 (proposed Site CSK-07B) began at 1700 h, ending Site U1593. The vessel arrived on location at 1830 h and Hole U1594A was spudded at 2310 h with Core U1594A-1H recovering 4.2 m, establishing the seafloor at 291.0 mbsl.

Core U1594A-1H was run through the whole-round physical properties track systems.

Daily Science Report for 21 January 2023

Location: Hole U1593C (proposed Site CSK-04C); 36°34.5060′N, 25°24.8995′E; water depth 404.0 m

Science Update: Cores U1593B-22F to 39F were retrieved from 148.2 to 232.8 mbsf, the final depth of this hole after reaching HLAPC refusal. The average recovery for today’s cored interval is 53% (0%–93%). Hole U1593B reached a maximum penetration of 232.8 mbsf with a cored interval of 232.8 m and a recovery of 156.78 m. The average recovery for the hole was 67%. The drill string was tripped up to the vessel and the RCB BHA was assembled. The vessel was offset 25 m to the north. Hole U1591C was spudded at 1752 h and drilled without recovery to 192 mbsf.

Cores U1593B-13F to 39F were run through the whole-round physical properties track systems. Cores U1593B-1H to 39F were split and described. The cores consist of ash, lapilli, lapilli-ash, lithic crystal ash, calcareous mud, nannofossil ooze, tuffaceous ooze, and sand. Microscopic analyses showed transparent and brown glass, volcanic lithics, authigenic pyrite, zeolite, iron and manganese oxides, rare amphiboles, feldspar, calcareous nannofossils, foraminifera, and sponge spicules.

Daily Science Report for 20 January 2023

Location: Hole U1593B (proposed Site CSK-04C); 36°34.4916′N, 25°24.9′E; water depth 404.0 m

Science Update: Cores U1593A-30F to 38F were retrieved from 208.2 to 250.6 mbsf, the final depth of this hole. The average recovery for this cored interval is 79% (8%–106%). In total, Hole U1593A reached a maximum penetration of 250.6 mbsf with a cored interval of 250.6 m and a recovery of 149.55 m. The average recovery for the hole was 60%. After refusal, the drill string was tripped out of the hole and the vessel was offset 50 m to the southeast. Hole U1593B was spudded at 0940 h. Recovery for Core U1593B-1H was 6.2 m with a calculated seafloor depth of 404.0 mbsl. Cores U1593B-1H to 21F were retrieved from 0 to 148.2 mbsf. The average recovery for today’s cored interval is 73% (0%–105%).

Cores U1593A-29F to 38F and U1593B-1H to 12H were run through the whole-round physical properties track systems. Cores U1593A-17F to 38F were split and described. The cores consist of ash, lapilli, lapilli-ash, nannofossil ooze, organic-rich ooze, tuffaceous ooze, and tuffaceous mud. Microscopic analyses showed high amounts of transparent glass, authigenic pyrite and calcite, zeolite, calcareous nannofossils, foraminifers, diatoms, and sponge spicules.

Daily Science Report for 19 January 2023

Location: Hole U1593A (proposed Site CSK-04C); 36°34.5103′N, 25°24.8765′E; water depth 402.5 m

Science Update: Hole U1593A was spudded at 0245 h with Core U1593A-1H recovering 4.7 m and a good mudline. Cores U1593A-1H to 29F were retrieved from 0 to 208.2 mbsf. The average recovery for today’s cored interval is 58% (1%–107%).

Cores U1593A-1H to 28F were run through the whole-round physical properties track systems. Cores U1593A-1H to 16H were split and described. The cores consist of calcareous mud, ash, lapilli, lapilli-ash, lapilli crystal ash, lithic ash, nannofossil ooze, organic-rich ooze, and tuffaceous ooze. Microscopic analyses showed high amounts of transparent and brown glass, volcanic lithics, authigenic pyrite and calcite, zeolite, pyroxenes, feldspar, biotite, iron and manganese oxides, calcareous nannofossils, foraminifers, diatoms, and sponge spicules.

Daily Science Report for 18 January 2023

Location: Site U1593 (proposed Site CSK-04C); 36°34.5120′N, 25°24.8760′E

Science Update: Cores U1592B-19R to 26R were retrieved from 450.2 to 527.8 mbsf, the final depth for this hole. The average recovery for today’s cored interval is 45% (0%–88%). In total, Hole U1592B reached a maximum penetration of 527.8 mbsf with a cored interval of 234.8 m and a recovery of 117.04 m. The average recovery for the hole was 50%. The drill bit cleared the rotary table at 2001 h, and the sea passage to Site U1593 started at 2100 h, ending Site U1592. The vessel completed the 16.7 nmi passage in 2.3 h at an average speed of 7.3 kt and arrived on location at 2306 h. The ship was switched to DP control at 2324 h.

Cores U1592B-18R to 26R were run through the whole-round physical properties track systems. Cores U1592B-16R to 26R were split and described. The cores consist of dolomitic sand, organic-rich nannofossil ooze, dolomitic ooze, sandy conglomerate, bioclastic sandy conglomerate, and alpine limestone basement. Microscopic analyses showed authigenic dolomite, calcareous nannofossils, foraminifers, and sponge spicules.

Daily Science Report for 17 January 2023

Location: Hole U1592B (proposed Site CSK-09A); 36°33.9161′N, 25°45.7027′E; water depth 693.1 m

Science Update: The drill ahead without recovery continued during the night from 286.8 to 293.0 mbsf. Cores U1592B-2R to 18R were retrieved from 293.0 to 450.2 mbsf. The average recovery for today’s cored interval is 45% (0%–88%).

Cores U1592B-2R to 17R were run through the whole-round physical properties track systems. Cores U1592B-2R to 15R were split and described. The cores consist of nannofossil ooze, organic-rich ooze with lapilli and shell fragments, tuffaceous mud, organic-rich mud, sand, dolomitic sand, and ash. Microscopic analyses showed transparent and brown glass, volcanic lithics, authigenic pyrite and calcite, iron and manganese oxides, zeolites, calcareous nannofossils, foraminifers, diatoms, radiolarians, sponge spicules, and shell fragments.

Daily Science Report for 16 January 2023

Location: Hole U1592B (proposed Site CSK-09A); 36°33.918′N, 25°45.703′E; water depth 693.1 m

Science Update: Cores U1592A-51X to 55X were retrieved from 320.8 to 339.2 mbsf. The average recovery for today’s cored interval is 58% (14%–112%). Following Core 55X, the drill string was pulled out of the hole, with the bit clearing the seafloor at 0915 h. The bit cleared the rig floor at 1120 h, ending Hole U1592A. In total, Hole U1592A reached a maximum penetration of 339.2 mbsf with a cored interval of 339.2 m and a recovery of 240.45 m. The average recovery for the hole was 71%. The vessel was offset 50 m to the southeast of Hole U1592A, the RCB BHA was assembled, and Hole U1592B was spudded at 1600 h. Hole U1592B was drilled without recovery to a depth of 286.8 mbsf.

Cores U1592A-51X to 55X were run through the whole-round physical properties track systems. Cores U1592A-46X to 55X were split and described. The cores consist of nannofossil ooze, organic-rich ooze, tuffaceous ooze, lithic sand, and calcareous sand. Microscopic analyses showed transparent and brown glass, volcanic lithics, authigenic pyrite and calcite, iron and manganese oxides, calcareous nannofossils, foraminifers, diatoms, radiolarians, sponge spicules, and shell fragments.

Daily Science Report for 15 January 2023

Location: Hole U1592A (proposed Site CSK-09A); 36°33.9358′N, 25°45.6784′E; water depth 693.1 m

Science Update: Cores U1592A-26F to 45F were retrieved from 179.8 to 269.1 mbsf. The average recovery for today’s cored APC/HLAPC interval is 20% (0%–88%). The core barrel got stuck at Core 45F and had to be drilled over. Starting with Core 46X operations were switched to XCB coring to Core 51X at 320.8 mbsf. The average recovery for today’s cored XCB interval is 9% (0%–47%).

Cores U1592A-14H to 50X were run through the whole-round physical properties track systems. Cores U1592A-11H to 45F were split and described. The cores consist of ash, vitric crystal ash, lithic lapillis, gravelly muddy sand, organic-rich calcareous mud, and nannofossil ooze. Microscopic analyses showed transparent and brown glass, volcanic lithics, authigenic pyrite and calcite, iron and manganese oxides, calcareous nannofossils, foraminifers, diatoms, radiolarians, and sponge spicules.

Daily Science Report for 14 January 2023

Location: Hole U1592A (proposed Site CSK-09A); 36°33.9358′N, 25°45.6784′E; water depth 693.1 m

Science Update: The ship began its transit to Site U1592 at 0230 h, ending Site U1590. The vessel arrived on location at 0356 h following a 15.5 nmi transit. Hole U1592A was spudded at 0830 h in a water depth of 693.1 mbsl. Cores U1592A-1H to 25F were retrieved from 0 to 179.8 mbsf. The average recovery for today’s cored interval is 83% (0%–106%).

Cores U1592A-1H to 13H were run through the whole-round physical properties track systems. Cores U1592A-1H to 10H were split and described. The cores consist of mud, nannofossil ooze, organic-rich ooze, tuffaceous ooze, ash, and lapilli-ash. Microscopic analyses showed transparent and brown glass, biotite, authigenic calcite, iron and manganese oxides, calcareous nannofossils, foraminifers, diatoms, and sponge spicules.

Daily Science Report for 13 January 2023

Location: Hole U1590B (proposed Site CSK-03A); 36°33.3129′N, 25°26.3644′E; water depth 397.1 m

Science Update: Cores U1590B-40R to 57R were retrieved from 460.1 to 634.7 mbsf. The average recovery for today’s cored interval is 9% (0%–47%). Shipboard P-wave velocities revealed that our precruise seismic velocities were slightly off, thus it was likely we might not be able to reach a foreseen stratigraphic target within the approved depth of 566 mbsf for this site. New seismic models and geochemical data were provided to the Environmental Protection and Safety Panel (EPSP) that approved Site U1590 to the new extended depth. The site was ended after Core U1590B-57R. In total, Hole U1590B reached a maximum penetration of 634.7 mbsf with a cored interval of 541.7 m and a recovery of 74.73 m. Average recovery for the hole was 14%. For the rest of today’s operations, the drill pipe was tripped out of the hole.

Cores U1590B-40R, 41R, 43R, 49R, 50R, 51R, 56R, and 57R were run through the whole-round physical properties track systems. Cores U1590B-31R to 33R, 39R to 41R, 43R, 49R to 50R, and 56R to 57R were split and described. The cores consist of nannofossil ooze, organic-rich ooze, tuffaceous ooze, calcareous tuffaceous mud, ash, and lapilli. Microscopic analyses showed transparent and brown glass, authigenic calcite and zeolite, iron and manganese oxides, foraminifers, calcareous nannofossils, diatoms, and sponge spicules.

Daily Science Report for 12 January 2023

Location: Hole U1590B (proposed Site CSK-03A); 36°33.3129′N, 25°26.3644′E; water depth 397.1 m

Science Update: Cores U1590B-18R to 39R were retrieved from 248.0 to 460.1 mbsf. The average recovery for today’s cored interval is 27% (0%–92%).

Cores U1590B-18R to 33R were run through the whole-round physical properties track systems. Cores U1590B-18R to 30R were split and described. The cores consist of calcareous mud, organic-rich calcareous mud, calcareous tuffaceous mud, mud, crystal ash, ash, nannofossil ooze, tuffaceous ooze, and organic-rich ooze. Microscopic analyses showed transparent and brown volcanic glass, authigenic pyrite and calcite, zeolite, iron and manganese oxides, calcareous nannofossils, foraminifers, diatoms, and sponge spicules.

Daily Science Report for 11 January 2023

Location: Hole U1590B (proposed Site CSK-03A); 36°33.3129′N, 25°26.3644′E; water depth 397.1 m

Science Update: With the experience gained at Hole U1590A, it was decided to drill ahead without recovery with the RCB bit to 93.0 mbsf. Similar to Hole U1590A, tight hole conditions were observed at 26.4 and 83.8 mbsf. Cores U1590B-2R to 17R were retrieved from 93.0 to 248.0 mbsf. As expected, recovery in softer sediments with the RCB bit was low to zero, but the improved hole integrity was deemed more important than recovery in the upper section. The average recovery for today’s cored interval is 1% (0%–2%).

Core U1590B-14R was run through the whole-round physical properties track systems. Cores U1590B-2R, 9R, 12R, and 14R were split and described. The cores consist of tuffaceous mud, nannofossil ooze, organic-rich ooze, and tuffaceous ooze. Microscopic analyses showed transparent and brown glass, calcareous nannofossils, foraminifers, and sponge spicules.

Daily Science Report for 10 January 2023

Location: Site U1590 (proposed Site CSK-03A); 36°33.313′N, 25°26.364′E

Science Update: Cores U1591C-68R to 71R were retrieved from 864.1 to 902.9 mbsf, the final depth for the hole. The average recovery for today’s cored interval is 74% (46%–98%). In total, Hole U1591C reached a maximum penetration of 902.9 mbsf with a cored interval of 668.6 m and a recovery of 384.47 m. Average recovery for the hole was 58%. The drill pipe was tripped out of the hole, with the bit clearing the seafloor at 1400 h and the drill floor at 1550 h. The ship began its transit to Site U1590 at 1648 h, ending Site U1591. After a 20.3 nmi transit, the thrusters were lowered on Site U1590 at 1924 h. Throughout the evening the new BHA was assembled, and some scheduled maintenance was performed.

Cores U1591C-56R and 57R and 68R to 71R were run through the whole-round physical properties track systems. Cores U1591C-53R to 57R and 67R to 71R were split and described. The cores consist of tuff, tuffaceous mudstone, organic-rich mudstone, marl, organic-rich marl, micrite, calcareous micrite, anhydritic micrite, anhydritic mudstone, brecciated anhydrite, nodular anhydrite, and anhydrite. Microscopic analyses showed common occurrences of transparent glass, altered volcaniclastics, authigenic pyrite and calcite, iron oxides, gypsum, and anhydrite.

Daily Science Report for 9 January 2023

Location: Hole U1591C (proposed Site CSK-20A); 36°18.7810′N, 25°8.9962′E; water depth 513.8 m

Science Update: Cores U1591C-57R to 67R were retrieved from 757.4 to 864.1 mbsf. The average recovery for today’s cored interval is 78% (52%–103%).

Cores 58R to 67R were run through the whole-round physical properties track systems and Cores 50R to 52R and 58R to 66R were split and described. Cores 56R and 57R have not been run through the track systems and Cores 53R to 57R have not yet been split and described because the subsequent cores contained evaporite sections that are prone to decay in the wetter conditions inside whole rounds. Thus, these cores were scanned and split as quickly as possible ahead of Cores 53R to 57R. The cores consist of marl, organic-rich marl, mudstone, tuffaceous mudstone, micrite, micritic sandstone, micrite with nodular gypsum, anhydritic micrite with nodular gypsum, nodular anhydrite, anhydritic mudstone, calcareous sandstone, and calcareous anhydrite. Microscopic analyses showed low amounts of transparent glass, rare authigenic pyrite, authigenic calcite, as well as gypsum and anhydrite minerals.

Daily Science Report for 8 January 2023

Location: Hole U1591C (proposed Site CSK-20A); 36°18.7810′N, 25°8.9962′E; water depth 513.8 m

Science Update: Cores U1591C-42R to 56R were retrieved from 611.9 to 757.4 mbsf. The average recovery for today’s cored interval is 64% (3%–103%).

Cores U1591C-41R to 55R were run through the whole-round physical properties track systems, and Cores U1591C-36R to 49R were split and described. The cores consist of marl, organic-rich marl, limestone, sandstone, mudstone, organic-rich mudstone, organic-rich calcareous mudstone, and calcareous mudstone.

Daily Science Report for 7 January 2023

Location: Hole U1591C (proposed Site CSK-20A); 36°18.7810′N, 25°08.9962′E; water depth 513.8 m

Science Update: Cores U1591C-24R to 41R were retrieved from 437.3 to 611.9 mbsf. The average recovery for today’s cored interval is 62% (2%–104%).

Cores U1591C-24R to 40R were run through the whole-round physical properties track systems, and Cores U1591C-21R to 35R were split and described. The cores consist of organic-rich mud, marl, organic-rich marl, marl with ash, tuffaceous marl, tuff, sandy conglomerate, organic-rich mudstone, and chert. Microscopic analyses showed amounts of transparent glass, altered volcanic lithics, authigenic calcite, authigenic zeolite, iron and manganese oxides, calcareous nannofossils, foraminifers, radiolarians, sponge spicules, and diatoms.

Daily Science Report for 6 January 2023

Location: Hole U1591C (proposed Site CSK-20A); 36°18.7810′N, 25°8.9962′E; water depth 513.8 m

Science Update: Cores U1591C-6R to 13R were retrieved from 187.4 to 265.0 mbsf. Following Core 13R, a second interval was drilled without recovery from 265.0 to 350.0 mbsf. Coring resumed with Cores 15R to 23R recovered from 350.0 to 437.3 mbsf. The average recovery for today’s cored intervals is 43% (4%–85%).

Cores U1591C-5R to 23R were run through the whole-round physical properties track systems, and Cores U1591C-4R to 20R were split and described. The cores consist of nannofossil ooze, organic-rich ooze, organic-rich mud, tuffaceous mud, calcareous tuffaceous mud, gravely tuffaceous sand, ash, lithic crystal ash, and cobbles of polymictic volcanic rocks. Microscopic analyses showed high amounts of transparent and brown volcanic glass, authigenic calcite, authigenic zeolite, iron oxides, rare foraminifers, sponge spicules, and unspecified organic material.

Daily Science Report for 5 January 2023

Location: U1591C (proposed Site CSK-20A); 36°18.7810′N, 25°8.9962′E; water depth 513.8 m

Science Update: Cores U1591B-41X to 43X were retrieved from 369.5 to 389.2 mbsf. At the end of Core 42X, the formation became difficult to drill, and we decided to advance by time. Progress was very slow and the hole was ended after Core 43X. Hole U1591B drilled an interval of 389.2 m, recovering 155.08 m of volcaniclastic sediments. The average recovery was 49% (0%–106%). The BHA for RCB coring was assembled and tripped back down to the mudline, spudding Hole U1591C in a water depth of 513.8 mbsl at 1500 h. Hole U1591C was drilled without recovery to 149.3 mbsf. Cores U1591C-2R to 5R were retrieved from 149.3 to 187.4 mbsf. The average recovery for today’s cored interval is 7% (0%–18%).

Cores U1591B-38X to 43X and U1591C-3R to 4R were run through the whole-round physical properties track systems, and Cores U1591B-37X to 43X and U1591C-3R were split and described. The cores consist of nannofossil ooze, organic-rich ooze, tuffaceous sand, tuffaceous mud, and ash. Microscopic analyses showed high amounts of nannofossils, transparent and brown glass, lithic fragments, altered volcaniclastics, authigenic pyrite, authigenic calcite, foraminifers, diatoms, and radiolarians.

At 1100 h, the science party held a meeting, discussing the findings of Holes U1591A and U1591B.

Daily Science Report for 4 January 2023

Location: Site U1591B (proposed Site CSK-20A); 36°18.7621′N, 25°9.0190′E; water depth 513.8 m

Science Update: Cores U1591B-24X to 40X were retrieved from 204.6 to 369.5 mbsf. The average recovery for today’s cored interval is 35% (0%–101%).

Cores U1591B-24X to 37X were run through the whole-round physical properties track systems, and Cores U1591B-22X to 36X were split and described. The cores consist of ooze (>50% calcareous nannofossils), organic-rich ooze, gravelly ooze, tuffaceous sand, and tuffaceous sandy conglomerate. Microscopic analyses showed high amounts of calcareous nannofossils, brown and transparent volcanic glass, authigenic calcite, diatoms, radiolarians, and foraminifers.

Daily Science Report for 3 January 2023

Location: Site U1591B (proposed Site CSK-20A); 36°18.7621′N, 25°9.0190′E; water depth 513.8 m

Science Update: Cores U1591B-4H to 23X were retrieved from 26.6 to 204.6 mbsf. Tight hole conditions required a drilled interval without recovery from 74.1 to 98.8 mbsf, switching to HLAPC below with Core 10F. Beginning at Core 14X, operations were switched to XCB coring. The recovery was low (0%–7%) in Cores 14X to 16X. We switched to HLAPC coring with Core 17F. The recovery increased to 44% but the formation firmed up, so operations had to be switched back to XCB coring at Core 19X. The average recovery for today’s cored interval is 58% (0%–105%).

Cores U1591B-1H to 23X were run through the whole-round physical properties track systems, and Cores U1591A-11H and U1591B-1H to 21X were split and described. The cores consist of lapilli ash, ash, tuffaceous muds, organic rich oozes and muds, tuffaceous ooze, and ooze. Microscopic analyses showed high amounts of volcanic glass, iron oxides, authigenic calcite, calcareous nannofossils, foraminifers, diatoms, radiolarians, unspecified organic material, and rare pyroxenes.

Daily Science Report for 2 January 2023

Locations:

  • Hole U1591A (proposed Site CSK-20A); 36°18.7615′N, 25°9.0057′E; water depth 514.6 m
  • Hole U1591B; 36°18.7621′N, 25°9.0190′E; water depth 513.8 m

Science Update: The vessel arrived on site at 0006 h and entered DP mode at 0014 h, marking the start of Site U1591. Hole U1591A was spudded at 0740 h. Cores U1591A-1H to 11H were retrieved from 0 to 98.8 mbsf. To minimize the time the drill string was not rotating and to keep the hole intact, we decided not to run the APCT-3 tool on this hole. While collecting Core 10H, the formation began to close in on the drill string and the torque on the string increased significantly. Thus, the decision was made to end the hole after Core 11H. The average recovery of Hole U1591A was 67% (1%–106%). The drill string was tripped back to the rig floor, disassembled, and a simplified BHA (no tapered or nonmagnetic collars) was assembled. Hole U1591B was spudded at 2150 h with Core U1598B-1H recovering 3.8 m and a good mudline. Seafloor depth was calculated to 513.8 mbsl. APC coring continued to 3H and a depth of 26.6 mbsf. The average recovery was 98% (94%–102%).

Cores U1591A-1H to 9H and 11H were run through the whole-round physical properties track systems, and Cores U1591A-1H to 9H were split and described. The cores consist of lapilli ash, ash, tuffaceous muds, organic rich ooze, tuffaceous ooze, and ooze. Microscopic analyses showed high amounts of volcanic glass, iron oxides, authigenic calcite, calcareous nannofossils, foraminifers, diatoms, radiolarians, and unspecified organic material.

Daily Science Report for 1 January 2023

Location: Underway to Site U1591 (proposed Site CSK-20A); 36°18.760′N, 25°09.006′E

Science Update: Core U1590A-1H recovered 4.3 m of sediment and the seafloor was calculated at 397.1 mbsl. Cores U1590A-1H to 11H were retrieved from 0 to 99.3 mbsf with an average recovery of 63% (17%–100%). The APCT-3 tool was run on Core U1590A-4H. At 42 mbsf (U1590A-5H) the formation changed and induced high torque on the drill string. Below that short interval, normal operations resumed. At 99.3 mbsf, the drill string got stuck after retrieval of Core 11H. Working the drill string for 3 h had no significant effect, and the drill string was severed at 1700 h at a depth of 4.6 mbsf. The vessel was secured for transit and began the 20.3 nmi transit to Site U1591 at 2148 h.

Cores U1590A-1H to 11H were run through the whole-round physical properties track systems and were split and described. The cores consist of muds and tuffaceous muds, pumice lapilli, calcareous tuffaceous muds, ash, lapilli ash, and nannofossil oozes. Microscopic analyses showed high amounts of glass, some pyrite, authigenic calcite, clay minerals, nannofossils, and foraminifera.

At 1300 h the meeting for Site U1589 took place in the conference room. All laboratory groups presented their most important findings and discussed challenges and solutions.