IODP Expedition 346

Asian Monsoon

Daily Science Report for 26 and 27 September 2013

LOCATION: In transit to/Arrived Busan, South Korea

SCIENCE UPDATE: The science party completed all shipboard work and submitted their science reports, revised sample requests, and research plans on 26 September. Expedition 346 ended when the ship arrived in Busan, South Korea, at 0651 h on 27 September.

Daily Science Report for 25 September 2013

LOCATION: In transit to Busan, South Korea

SCIENCE UPDATE: Cores U1245E-1H to ‑13H extended from 0 to 113.1 m and recovered 107.75 m of sediment. The last core of Expedition 346 arrived on deck at 0245 h, and we began the transit to Busan, South Korea, at 1012 h. In total, Expedition 346 obtained 6,135 m of core with an excellent recovery percentage (101%). This is an IODP record amount of core to be recovered by any single expedition. Scientists continue to revise personal sample requests and work on site reports. An outreach and education event was successfully held with three schools in the United States.

Daily Science Report for 24 September 2013

LOCATION: Hole U1425E (39°29.4392′N, 134°26.5607′E; 1909 m water depth) SCIENCE UPDATE: We arrived at Site U1425 at 1430 h. Once the vessel was stabilized over the location coordinates, rig floor operations began. Hole U1425E was spudded at 1945 h and APC Cores U1425E-1H to ‑7H penetrated from the seafloor to 57.7 m, recovering 54.42 m of sediment (94%). Scientists continued to discuss postcruise research strategies, revise their sample requests, and work on their site reports. An outreach and education event was successfully held with a school in Portugal.

Daily Science Report for 23 September 2013

LOCATION: In transit to Site U1425

SCIENCE UPDATE: Site U1427 coring operations were completed at 1530 h with the recovery of Cores U1427C-25H to ‑52H (220.5–351.1 m). Total core recovery for Hole U1427C was 367.77 m (105%). Hole U1430C was displaced with heavy mud, the drill string pulled back on deck, and the rig floor secured for transit. By 1900 h we were underway to Site U1425, where we plan to core a new hole to 110 m to provide additional material for postcruise studies. The total core recovery for Expedition 346 is now at 6027 m, a new record for IODP. Scientists continue to work on site reports, and to revise and update their individual sample requests. An outreach and education event was successfully held with three U.S. schools simultaneously.

Daily Science Report for 22 September 2013

LOCATION: Hole U1427C (35°57.93′N, 134°26.09′E; 326 m water depth)

SCIENCE UPDATE: The 182 nmi transit to Site U1427 was completed at 0830 h at an average speed of 10.5 kt. The vessel was maneuvered over the location coordinates and the vessel was turned over to dynamic position control. By 0900 h the vessel was stabilized for rig floor operations to begin in Hole U1427C. Hole U1427C was spudded at 1200 h. Cores U1427C-1H to ‑24H penetrated from the seafloor to 220.5 m and recovered 224.14 m of core (102%). Whole-round core sections from Hole U1427C are being measured for physical properties, split, and described. Geochemical analyses of interstitial water and sediment samples from Site U1430 are completed. Scientists are working on their site reports, and updating their individual sample requests.

Daily Science Report for 21 September 2013

LOCATION: In transit to Site U1427

SCIENCE UPDATE: We completed coring operations at Site U1430. APC Cores U1430C-17H through ‑34H extended the hole from 142.5 to 250 m with a recovery of 109.8 m (102%). Hole U1430C was displaced with mud, the drill string was pulled back on deck, and the rig floor was secured for transit. Our sea passage to return to Site U1427 started at 1518 h. The plan for the next site is to core a new hole to ~350 m to provide additional material for high-resolution paleoceanographic studies. Expedition scientists continue to describe and analyze samples from Site U1430 while working on their site reports, and discuss post-expedition research plans and individual sample requests.

Daily Science Report for 20 September 2013

LOCATION: Hole U1430C (37°54.1′N, 131°32.2′E; 1073 m water depth)

SCIENCE UPDATE: Hole U1430B was conditioned for wireline logging and the bit was pulled up to 80 m. Rig up started at 0200 h. The Triple-combo wireline logging tool string was split into two shorter strings to maximize data acquisition in the lowest part of the hole. Both triple-combo strings and the FMS-sonic tool string were able to reach to the bottom of Hole U1430B (~272 m WSF). They recorded resistivity, spectral gamma ray, density, caliper, magnetic susceptibility, and sonic velocities of the formation, as well as high-resolution resistivity images of the borehole walls. Logging operations were completed by 1600 h. Soon after, the ship was offset 15 m south of Hole U1430A, the drill bit positioned 2 m higher than for Hole U1430B, and Hole U1430C was started at 1645 h. Core U1430C-1H recovered 4.78 m and established a seafloor depth of 1073 m. APC coring continued, recovering Cores U1430C-2H to ‑16H (to 142.5 m) by midnight. Total core recovery for today was 147.2 m (103%). The Sample Allocation Committee met with the science party to discuss post-expedition research plans and individual sample requests. An outreach and education event was held successfully at midnight with three U.S. schools simultaneously.

Daily Science Report for 19 September 2013

LOCATION: Hole U1430B (37°54.1670′N, 131°32.2501′E; 1072 m water depth)

SCIENCE UPDATE: Following the end of coring operations in Hole U1430A, the hole was displaced with mud and the drill string pulled out of the hole. The ship was offset 15 m north of Hole U1430A, and Hole U1430B was spudded at 0330 h. Cores U1430B-1H to ‑37H penetrated from the seafloor to 275 m, recovering 259.71 m (94%). Cores U1430B-29X to ‑36X (from 246 to 274.1 m) were taken with the XCB coring system with a core recovery of 21%. By midnight, Hole U1430B was being conditioned for wireline logging. The cored interval from ~80 to 250 m in Hole U1430A consists of dark brown silty clay, with extensive biosiliceous laminated intervals. Below ~250 m to the bottom of the hole (274.4 m), the lithology changes to glauconitic sand and sandstone. The estimated age at ~240 m (Core U1430A-27H) is between 11.7 and 13.1 Ma. Geochemical analyses of interstitial water and sediment samples from Hole U1430A are ongoing. Additionally, Core U1430B-1H was thoroughly Rhizon-sampled with the objective of studying the relationship between the sediment magnetic signature and pore water chemistry, with implications for iron (Fe) sources. Expedition scientists began to review and discuss sample requests and post-expedition research plans.

Daily Science Report for 18 September 2013

LOCATION: Hole U1430A (37°54.1595′N, 131°32.2499′E; 1084 m water depth)

SCIENCE UPDATE: We arrived at Site U1430 at 0018 h. The thrusters and hydrophones were lowered, the APC/XCB Bottom Hole Assembly was made up, and the positioning beacon was deployed while lowering the drill string to the seafloor. Hole U1430A was started at 0445 h establishing a seafloor depth of 1084 m with Core U1430A-1H. APC coring continued using full length non-magnetic core barrels to 230.7 m (Cores U1430A-1H to ‑25H), followed by half-length non-magnetic core barrels to 249.5 m (Cores U1430A-26H to ‑29H); at that point we switched to the XCB system and recovered Cores U1430A-30X to ‑32X. Total recovery for today was 258.2 m of core (94%). Successful formation temperature measurements were taken at 32.1, 60.6, 89.1, and 117.6 m. The measured geothermal gradient in Hole U1430A is 98°C/km and the bottom water temperature is 0.6°C. Cores U1430A-1H to ‑10H have been measured for physical properties and described. The interval consists of color banded, biosiliceous, clay and silty clay, with finely laminated intervals, and numerous cm-thick tephra layers down to 80 m. The age at the base of Core U1430A-10H (89.1 m) is estimated at ~7 Ma. We held the Sites U1428/U1429 science summary meeting and an education live cast event with the University of Perpignan, in France.

Daily Science Report for 17 September 2013

LOCATION: In transit to Site U1430 (UB-1A)

SCIENCE UPDATE: Today the ship continued its sea passage from Site U1428 in the East China Sea to Site U1430 in the Sea of Japan/​East Sea, traveling 250 nmi at 10.4 kt. During the transit, the science party finished physical properties measurements and lithologic description of all cores from Sites U1428 and U1429, continued geochemical analyses, and worked on site reports. The Chief Scientists presented the scientific objectives and operations plan for Site U1430 (proposed site UB-1A) to the science party. The operations plan at Site U1430 is to drill three holes. The first hole will be drilled to acoustic basement (~285–335 m) and wireline logged. The next two holes will be cored to ~285 m.

Daily Science Report for 16 September 2013

LOCATION: In transit to Site U1430 (UB-1A)

SCIENCE UPDATE: Coring operations at Site U1428 ended at 0130 h, and the rig was secured for transit. The thrusters were raised and the ship started the voyage to Site U1430 (proposed site UB-1A) at 0418 h. Scientists continue to measure, describe and analyze samples from Sites U1429 and U1428. The EPM gave a presentation on post-expedition meetings, publications, and end-of-cruise preparations.

Daily Science Report for 15 September 2013

LOCATION: Hole U1428B (31°40.6483′N, 129°02.0004′E, 735.8 m water depth)

SCIENCE UPDATE: Today we completed coring operations at Site U1429. Cores U1429C-5H to ‑24H extended from 32.6 to 179.2 m and recovered 147 m (100%). Total core recovery at Site U1429 is 571.7 m (105%). After completing Site U1429, we returned to Site U1428 to drill an additional hole that provided material to build a complete spliced section spanning the last ~0.3 Ma and additional material for high resolution paleoceanographic studies. Cores U1428B-1H to ‑16H extended from seafloor to 143.3 m and recovered 145.85 m (102%).

Daily Science Report for 14 September 2013

LOCATION: Hole U1429C (31°37.0′N, 128°59.8′E, 744 m water depth)

SCIENCE UPDATE: Today we completed Holes U1429A (Cores U1429A-7H to ‑23H; 0 to 188.3 m; 190.3 m recovered) and U1429B (Cores U1429B-1H to ‑22H; 0 to 186.2 m; 190.7 m recovered), and started Hole U1429C. Cores U1429C-1H to ‑4H penetrated from the sea floor to 32.6 m and recovered 33.67 m (103%). Hole U1429B consists of diatom bearing nannofossil ooze with foraminifers. The age of the stratigraphic interval cored at Site U1429 spans the last 400,000 y.

Daily Science Report for 13 September 2013

LOCATION: Hole U1429A (31°37.0388′N, 128°59.8509′E, 743.7 m water depth)

SCIENCE UPDATE: Cores U1428A-19H to ‑32H penetrated from 150.1 to 211.5 m and recovered 23.23 m of sediment (38%). Coring operations in Hole U1428A, and at Site U1428, were concluded after a series of partial strokes and no recovery with the APC coring system, combined with drilled intervals, failed to effectively penetrate and recover a thick sand bed that started at ~135 m in Hole U1428A. Final core recovery for Hole U1428A was 178.9 m (103%). The sedimentary succession consists of diatom bearing nannofossil ooze with foraminifers. The age at the base of the succession is estimated at 0.29–0.44 Ma based on biostratigraphic markers. The geochemistry team continues to analyze samples from Sites U1427, U1428 and U1429. The upper 15 cores from Hole U1428A were Rhizon-sampled for high resolution interstitial water analyses. The science party presented the scientific results from Site U1427.

The ship was underway to Site U1429 (alternate site ECS-1C) at 1030 h. During the transit, a Japanese Coast Guard helicopter arrived on deck to evacuate a member of the science party who required medical attention. The medical evacuation was concluded at 1100 h and the ship arrived at the location of Site U1429 at 1200 h. After making up the APC/XCB bottom hole assembly and running the drill string down to sea bed, we deployed the underwater camera and began 25 m × 25 m sea floor survey. No obstructions were observed and Hole U1429A was spudded at 2045 h. Cores U1429A-1H to ‑6H (from 0 to 51.6 m) were taken by midnight with a recovery of 53.2 m (103%).

Daily Science Report for 12 September 2013

LOCATION: Hole U1428A (31°40.6391′N, 129°02.0003′E, 735.4 m water depth)

SCIENCE UPDATE: We completed the 468.5 nmi transit to Site U1428 (proposed site ECS-1B) at 0500 h. After making up the APC/XCB bottom hole assembly and running the drill string down to the sea bed, we deployed the underwater camera and began an inspection of the seafloor to ensure that it was free of obstructions before coring operations began at Hole U1428A. No obstructions were observed. Hole U1428A was spudded at 1230 h and the discharge of the mudline core was watched through the subsea camera system. Cores U1428A-1H to ‑18H extended from the seafloor to 150.1 m and recovered 155.6 m (104%). The cored interval in Hole U1428A consists of nannofossil ooze. The age at the base of Core U1428A-13H is estimated at 0.29 Ma based on calcareous nannofossils. An outreach and education event was conducted with the J. L. Newton Elementary (Fairhope, Alabama), Ann Richards School (Austin, Texas), Marina del Rey Middle School (Los Angeles, California), and the Montgomery Bell Academy (Nashville, Tennessee).

Daily Science Report for 11 September 2013

LOCATION: In transit to Site U1428 (ECS-1B)

SCIENCE UPDATE: Cores U1427B-19H through ‑50H were described today. As in Hole U1427A, the sediment succession obtained in the cored interval from Hole U1427B consists of olive gray to gray, silt to silty clay, with variable amounts of calcareous and siliceous microfossils. The Chief Scientists presented the research objectives for Site U1428 to the science party. The operations plan for this site is to APC/XCB core two holes to ~600 m and ~800 m, and to wireline log the deepest hole with the paleo combo, FMS-sonic, and Versatile Seismic Imager (VSI) tool strings. A third hole may be cored depending upon the depth/age achieved in the first two holes. After a medical evacuation to a Japanese tug boat was completed at 0754 h, we got underway for Site U1428 with an ETA of 0600 h on 12 September.

Daily Science Report for 10 September 2013

LOCATION: Sea of Japan/​East Sea, in transit to Site U1428 (ECS-1B)

SCIENCE UPDATE: We completed coring operations in Hole U1427B with Cores U1427B-61H to ‑65H reaching 405.6 m. Total core recovery for Hole U1427B was 422.41 m (105%). Scientists continue to measure and describe cores from Hole U1427B. Our transit to Site U1428 (proposed site ECS-1B) began at 0830 h with an ETA of 0600 h on 12 September. During the transit, we will rendezvous with a Japanese boat at 0800 h on 11 September to conduct a non-emergency medical evacuation of a member of the scientific party.

Daily Science Report for 9 September 2013

LOCATION: Hole U1427B (35°57.9276′N, 134°26.0600′E, 337 m water depth)

SCIENCE UPDATE: APC coring continued in Hole U1427B using non-magnetic core barrels. Cores U1427B-5H to ‑60H penetrated from 33.3 to 382.1 m, and recovered 397.1 m of core (105%). Cores U1427B-37H to ‑60H were taken with the half-length APC system. Cores 1H to 82X from Hole U1427A have been measured for physical properties and described. The sediment succession consists of olive gray and gray, silt to silty clay with variable amounts of calcareous and siliceous microfossils. Tephra beds are less frequent and generally thinner at this site than at the previous ones. Interstitial water samples are being measured for hydrogen sulfide content to better define the sulfate methane transition zone at the Expedition 346 sites. All other pore water geochemical analyses (whole-round and Rhizon samples) are being finalized.

Daily Science Report for 8 September 2013

LOCATION: Hole U1427B (35°57.9′N, 134°26.0′E, 337 m water depth)

SCIENCE UPDATE: XCB Cores 84X to 87X extended Hole U1427A from 509.8 to 548.6 m, recovering 25.6 m (66%), and ending coring operations in this hole. Subsequently, Hole U1427A was conditioned for downhole logging and the bit was pulled up to 80 m. Both the paleo-combo and the FMS-sonic tool strings were deployed to the bottom of Hole U1427A. They recorded resistivity, spectral gamma ray, density, caliper, magnetic susceptibility, and sonic velocities of the formation, as well as high resolution resistivity images of the borehole walls. Following logging operations, the bit was lowered to 519 m and Hole U1427A was displaced with cement. The drilled string was pulled out of the hole and the vessel offset 15 m north. Hole U1427B was started at 2220 h. By midnight, Cores U1427B-1H to ‑4H had penetrated from the seafloor to 33.3 m, and recovered 34.1 m of core (102%). In the laboratories, we continue to measure, describe, and analyze core samples from Hole U1427A. We also held a meeting to present the scientific highlights of Site U1426.

Daily Science Report for 7 September 2013

LOCATION: Hole U1427A (35°57.9200′N, 134°26.0604′E, 337 m water depth)

SCIENCE UPDATE: Coring continued in Hole U1427A using the half-length APC system from 266.3 to 490.4 m, and then with the XCB coring system to 509.8 m. The objective is to continue coring Hole U1427A to 550 m. APC Cores U1427A-34H to ‑81H recovered 241.9 m of sediment (108%). XCB Cores U1427A-82X and ‑83X recovered 1.54 m (8%). We finished describing all cores from Site U1426 and started describing cores from Site U1427. The interval recovered in Cores U1427A-1H to ‑16H consists of greenish gray clayey silt with varying proportions of calcareous and siliceous biogenic components. Carbonate preservation is excellent at this site. The age at the base of Core U1427A-67H is estimated at less than 1.14 Ma.

Daily Science Report for 6 September 2013

LOCATION: Hole U1427A (35°1.99′N, 134°47.99′E, 337 m water depth)

SCIENCE UPDATE: We completed the 66.4 nmi transit to Site U1427 (proposed site YB-1) at 0542 h. Hole U1427A was spudded at 0925 h. Coring continued using full-length non-magnetic core barrels to 228.7 m (Cores U1427A-1H to ‑25H). At that point, we switched to the half-length APC coring system and recovered Cores U1427A-26H to ‑34H (228.7 to 266.3 m). Total recovery for today was 278.4 m of core (103%). The age at the base of Core U1427A-18H (163 m) is estimated at >0.29 Ma. Successful formation temperature measurements were taken at 30.3, 58.8, 87.3, and 115.8 m. Over the last 24 h we measured over 30 headspace samples from Hole U1427A and we processed 23 interstitial water samples. Additionally, we are finishing up the geochemical analyses of samples from the previous Site U1426 and continue to describe cores from Hole U1426C.

Daily Science Report for 5 September 2013

LOCATION: Sea of Japan/​East Sea, in transit to Site U1427 (YB-1)

SCIENCE UPDATE: We concluded coring operations at Site U1426 after completing Holes U1426B, U1426C, and U1426D to 34.7 m, 204 m, and 99.4 m, respectively. A total of 38 cores were taken today recovering 35.8 m (103%) in Hole U1426B, 211.9 m (104%) in Hole U1426C, and 103.7 m (104%) in Hole U1426D. The four cores taken from Hole U1426B were sampled for high resolution geochemical analyses. All cores from Site U1426 have been measured for physical properties. Over 250 m of core are waiting to be split and described, as we try to keep up with the pace of rapid and high core recovery from Site U1426. Additional core racks were built today to cope with possible core overflow at Site U1427, the next site of the expedition, and the one at the shallowest water depth (327 m). By 2345 h, we had secured the rig for transit, raised the thrusters and hydrophones, and began the sea passage to Site U1427 (proposed site YB-1).

Daily Science Report for 4 September 2013

LOCATION: Hole U1426A (37°2.00′N, 134°48.00′E, 914.4 m water depth)

SCIENCE UPDATE: Coring in Hole U1426A was concluded at 2330 h. Cores U1426A-25H to ‑59H extended from 218.2 m to 396.7 m and recovered 187.4 m of core (105%). The drill string was pulled out of the hole and the vessel offset 15 m north, as we prepared to start Hole U1426B. The cored interval between Cores U1426A-7H and ‑20H (59 to ~182 m) consists of dark greenish gray foraminifer-rich clay, interbedded with light greenish gray clay with detrital carbonate. Below ~182 m to ~260 m (Core U1426A-30H), the main lithologies are diatom ooze and diatom rich clay. Biostratigraphic results provide an age estimate of more than 5.54 Ma for the base of Core U1426A-48H (345 m). Tropical storm Toraji weakened as predicted, and is no longer a threat to on-site operations. A meeting was held at noon to discuss the scientific highlights from Site U1425.

Daily Science Report for 3 September 2013

LOCATION: Hole U1426A (37°2.00′N, 134°48.00′E, 914 m water depth)

SCIENCE UPDATE: We completed the 148 nmi transit to Site U1426 (proposed site YB-2) at 0636 h. The vessel was maneuvered over the location coordinates, thrusters were lowered, the positioning beacon was deployed, and the vessel was turned over to dynamic position control. Hole U1426A was spudded at 1125 h. By midnight, we had obtained Cores U1426A-1H to ‑24H, extending from the seafloor to 218.2 m, and recovering 231.4 m of core (104%). Cores U1426A-1H to ‑6H have been split. The sedimentary interval revealed in these cores consists of dark greenish gray foraminifer-rich clay, interbedded with light greenish gray clay with detrital carbonate. Fine scale laminations occasionally occur in the dark intervals. The age at the base of Core U1426A-13H (116.5 m) is estimated at ~1.34–1.73 Ma. We are monitoring tropical storm Toraji, now located 400 nmi southwest of our location. This storm is forecast to become a tropical depression within 24 h, and is not considered a threat to on-site operations at this time.

Daily Science Report for 2 September 2013

LOCATION: Sea of Japan/​East Sea, in transit to Site U1426 (YB-2)

SCIENCE UPDATE: We completed coring operations in Hole U1425D alternating between the half-length APC and the XCB coring systems, thus ending operations at Site U1425. Cores U1425D-64H to ‑72H extended from 397.7 to 431 m recovering 12 m of core (36%). The sedimentary interval recovered in Cores U1425D-21H to ‑45H consists of moderate to heavily bioturbated diatomaceous silty clay and clay, and diatom ooze. The age at the base of Core U1425D-61H (390.7 m) is estimated at >12.5 Ma based on radiolarian biostratigraphy. We finished analyzing sediment samples from Site U1425 for carbonate and total organic carbon during the transit to Site U1426. Methane concentrations at Site U1425 are similar to those measured at Site U1422, and are much higher at these sites than at Sites U1423 and U1424. We continue to analyze samples for interstitial water (IW) chemistry and are starting to compare the results from the Rhizon and IW sample methods in the upper 20–30 m of the cored section. Dissolved silica measurements taken from our deepest depths to date indicate important changes in silica water chemistry at ~330 m at Site U1425.

Daily Science Report for 1 September 2013

LOCATION: Hole U1425D (39°29.4392′N, 134°26.5395′E, 1920 m water depth)

SCIENCE UPDATE: We continue to core Hole U1425D, alternating between the full and half-length APC core barrels. Cores U1425D-30H to ‑63H extended from 238.8 m to 397.7 m and recovered 158.9 m (104%). As was the case in Hole U1425B, the sedimentary interval recovered in Cores U1425D-1H through ‑20H mainly consists of color-banded greenish gray clay and olive green silty clay above Core U1425D-3H (lithologic Unit I), and dark grayish brown diatom ooze downhole. We held a live education and outreach event with the School of Environmental and Rural Science at the University of New England, in Australia. A fire and abandon ship safety drill was conducted in the afternoon, followed by the official Expedition 346 group photo.