IODP Expedition 353

Indian Monsoon Rainfall

Daily Science Report for 28 January 2015

Location: At anchorage outside of Loyang, Singapore

Science Update: The science laboratory teams are finalizing reports and their postcruise research sample lists. The vessel is presently at anchorage outside of Singapore and is estimated to dock at 1530 h.

Daily Science Report for 27 January 2015

Location: In transit to Singapore

Science Update: The science laboratory teams are working on the Site U1448 report and revising the methodology sections. The scientists are finalizing their postcruise research plans and creating sample lists. The scientists also presented results from Site U1448. The vessel is scheduled to arrive at the pilot station in Singapore at 0600 h on 29 January.

Daily Science Report for 26 January 2015

Location: In transit to Singapore

Science Update: The science laboratory teams are working on the Site U1447 and U1448 reports and revising the methodology sections. The Indian Monsoon scientists presented results from Site U1447. The technical staff began cleaning the laboratory spaces. The vessel is scheduled to arrive at the pilot station in Singapore at 0600 h on 29 January.

Daily Science Report for 25 January 2015

Location: In transit to Singapore

Science Update: Hole U1448C was spudded at 0750 h. Cores U1448C-1H to 4H were retrieved with 101% core recovery. The final core on deck for the expedition arrived at 0935 h. The drill pipe was pulled from the hole, the beacon was recovered, and the vessel was secured for transit. The vessel began the transit to Singapore at 1542 h.

Cores U1448B-31F to 58F contain greenish gray nannofossil-rich clay and Cores U1448C-1H to 4H contain greenish gray nannofossil-rich clay with foraminifers. All of the cores from Site U1448 have been described. Paleomagnetic measurements for Site U1448 are ongoing.

Daily Science Report for 24 January 2015

Location: Hole U1448C (10°38.0830′N, 93°00.0233′E; 1096.8 m water depth)

Science Update: Following APC coring at Hole U1448B, the hole was advanced 1.5 m without coring for the purpose of stratigraphic correlation. Cores U1448B-21F to 58F (179.5–358.6 mbsf) were cored using the half-length APC (HLAPC) system. Core recovery for this interval was 105%. The drill string was pulled from the hole and cleared the seafloor at 0630 h on 25 Janaury.

Cores U1448B-1H to 30F contain greenish gray nannofossil-rich clay with foraminifers and clay with nannofossil or foraminifers. Volcanic ash layers are observed in Sections U1448B-1H-4 and 6H-1. The chemistry laboratory is completing analyses and all of the moisture and density samples have been measured.

Daily Science Report for 23 January 2015

Location: Hole U1448B (10°38.03′N, 93°00.00′E; 1096.5 m water depth)

Science Update: Cores U1448A-53X to 60X (343.4–421.0 mbsf) were cut using the XCB system and had 101% core recovery. The pipe was pulled from the hole and cleared the seafloor at 1830 h. The vessel was offset 20 m to the south and Hole U1448B was spudded at 2010 h. Cores U1448B-1H to 19H (0–177.7 mbsf) were retrieved with 102% core recovery. Temperature measurements were made on Cores U1448B-4H, 7H, 10H, and 15H.

Cores U1448A-36F to 60X were described. From Core U1448A-36F to Section U1448A-56X-5, the dominant lithology is greenish gray nannofossil-rich clay or clay with nannofossils. Within Section U1448A-56X-5 is a hiatus that spans ~8 m.y. The nannofossil biostratigraphy indicates that the sediment above the hiatus is between 6.91–7.42 Ma and below is between 14.91–15.8 Ma. The sediments from Section U1448A-56X-5 to Core U1448A-60X are greenish gray clayey biosiliceous oozes with nannofossils. The age of the base of Hole U1448A is >15.8 Ma.

Daily Science Report for 22 January 2015

Location: Hole U1448A (10°38.0315′N, 93°00.0036′E; 1098.3 m water depth)

Science Update: Cores U1448A-15H to 23H (125.9–204.2 mbsf) were recovered using the APC system. Following two partial strokes with the APC system, the half-length APC (HLAPC) system was deployed and Cores U1448A-24F to 52F (204.2–343.4 mbsf) were retrieved with 105% core recovery. The total depth for Hole U1448A is 420 mbsf.

Cores U1448A-8H to 35F contain greenish gray clay with nannofossils or foraminifers and nannofossil-rich clay. The cores are mottled from bioturbation and contain wood fragments. Few thin silt to sand layers are observed in the cores, which are likely turbidites. A volcanic ash is present in Section U1448A-28F-2. Foraminifer preservation is good and nannofossil biostratigraphy indicates that the age of Core U1448A-52F is latest Miocene.

Daily Science Report for 21 January 2015

Location: Hole U1448A (10°38.03′N, 93°00.00′E; 1098.3 m water depth)

Science Update: Cores U1447C-16H to 18H (132.4–160.9 mbsf) were retrieved with 87% core recovery. The pipe was pulled from the hole and cleared the seafloor at 1405 h. The remaining drill pipe was tripped during the 9.4 nmi transit to Site U1448 (proposed site AA-4B). The vessel was offset to Site U1448 using dynamic positioning and arrived on site at 1845 h. Hole U1448A was spudded at 0010 h on 22 January. Cores U1448A-1H to 14H (0–125.9 mbsf) were retrieved with 104% core recovery.

Cores U1447C-17H and 18H contain greenish gray foraminfer-rich nannofossil ooze with clay and beds of silt to sand, which are likely turbidites. Cores U1448A-1H to 7H contain greenish gray nannofossil-rich clay with foraminifers. The cores are mottled and pyrite nodules and gastropod shells are observed. Two ash layers have been identified in Sections U1448A-2H-3 and 6H-3. Diatoms are very rare in Samples U1448A-10H-CC to 14H-CC and are not found elsewhere in the hole. Foraminifers are well-preserved and nannofossil biostratigraphy indicates that the age of Core U1448A-15H is ~2 Ma.

Daily Science Report for 20 January 2015

Location: Hole U1447C (10°47.41′N, 93°00.00′E; 1392.3 m water depth)

Science Update: Cores U1447A-86X to 88X (711.5–738.0 mbsf) were cut with 29.25 m of core recovered (110%). The total core recovery for Hole U1447A is 99%. The hole was displaced with heavy mud and the pipe was pulled from the hole. The pipe cleared the seafloor at 1705 h. The vessel was offset 20 m to the south and Hole U1447B was spudded at 2045 h. Cores U1447B-1H to 3H (0–24.4 mbsf) were recovered. The pipe was pulled from the hole and cleared the seafloor at 2220 h. The vessel was offset 20 m to the east and Hole U1447C was spudded at 2300 h. Thus far, Cores U1447C-1H to 15H (0–132.4 mbsf) have been retrieved with 102% core recovery.

Cores U1447A-83X to 88X, U1447B-1H to 3H, and U1447C-1H to 7H have been described. Cores U1447A-83X to 88X contain greenish gray mottled biosilica-rich clay with nannofossils. Cores U1447B-1H to 3H and U1447C-1H to 7H contain greenish gray clay-rich nannofossil ooze with foraminifers and nannofossil-rich clay with foraminifers. An ash layer, which may be the Toba ash, is found in Section U1447B-3H-1. A thick (~1 m) sandy bed composed of lithic material and shell fragments is found in Cores U1447B-1H and U1447C-1H and corresponds to the thick sandy bed found in Section U1447A-2H-1. The biostratigraphic datums suggest that the age of the base of Hole U1447A is between 9–10 Ma; however, age refinement is ongoing.

Daily Science Report for 19 January 2015

Location: Hole U1447A (10°47.4061′N, 92°59.9999′E; 1390.9 m water depth)

Science Update: Cores U1447A-73X to 85X (595.0–711.5 mbsf) were cut with 120.32 m of core recovered (103%). Coring at Hole U1447A will continue to 738 mbsf.

Cores U1447A-67X to 82X contain greenish-gray nannofossil-rich clay with biosilica and biosilica-rich clay with nannofossils. The cores are mottled from bioturbation. Volcanic ashes are observed in Core U1447A-76X. Foraminifer preservation is good. Nannofossil and diatom biostratigraphy indicate that the age of Sample U1447A-85X-CC is ~9–9.5 Ma. The porosity of the cores decreases from the top of the hole to Core U1447A-45X, remains constant to Core 58X, and increases to Core 64X.

Daily Science Report for 18 January 2015

Location: Hole U1447A (10°47.4061′N, 92°59.9999′E; 1390.9 m water depth)

Science Update: Cores U1447A-56X to 72X (430.1–595.0 mbsf) were cut with 153.4 m of core recovered (93%). XCB coring will continue to a total depth of 738 mbsf.

Cores U1447A-54X to 63X contain clayey nannofossil ooze and Cores U1447A-64X to 66X contain clayey nannofossil ooze with glauconite. The cores show bioturbation and burrows are present. Biscuiting from XCB coring is found throughout the cores. Nannfossil and planktonic foraminifer biostratigraphy indicate that Core U1447A-59X is Miocene in age. Diatoms are present in Samples U1447A-68X-CC to 72X-CC. Diatom and nannofossil biostratigraphy suggest that the age of Sample U1447A-72X-CC is < ~7.5 Ma. Overall, the nannofossil, planktonic foraminifer, and diatom biostratigraphy agree well.

Daily Science Report for 17 January 2015

Location: Hole U1447A (10°47.4061′N, 92°59.9999′E; 1390.9 m water depth)

Science Update: Cores U1447A-41F to 44F (313.8–328.8 mbsf) were retrieved using the HLAPC system with 103% core recovery. Cores U1447A-41F, 43F, and 44F had partial strokes and the core liner was pumped out of Core U1447A-44F. The XCB system was deployed beginning with Core U1447A-45X and continued through U1447A-55X (328.8–430.1 mbsf).

Cores U1447A-23H to 53X contain greenish-gray clayey nannofossil ooze and clayey calcareous ooze. Thin silty to sandy beds, likely turbidites, are observed in Cores U1447A-23H to 46X. Pyrite nodules are present in Cores U1447A-47X to 53X. The nannofossil and planktonic foraminifer biostratigraphy agree well. Planktonic foraminifers are dominant and have good preservation. The planktonic-benthic foraminifer ratio is high. Diatoms are barren in these cores. From 220–260 m, the sediments have normal polarity. This interval likely corresponds to the Olduvai chron (1.778–1.954 Ma).

Daily Science Report for 16 January 2015

Location: Hole U1447A (10°47.4061′N, 92°59.9999′E; 1390.9 m water depth)

Science Update: Cores U1447A-11H to 29H (88.0–261.0 mbsf) were retrieved using the APC system and had 103% core recovery. Following six partial strokes with the full-length APC, the half-length APC (HLAPC) was deployed for Cores U1447A-30F to 40F (261.0–313.8 mbsf).

Cores U1447A-7H to 22H are comprised of greenish-gray foraminifer-rich nannofossil ooze with clay and clayey nannofossil ooze with formainifers. Thin to thick beds of bioclastic silt to sand are present in Cores U1447A-16H to 22H, and are most likely turbidites. Bioturbation is observed throughout the cores. A thick (63 cm) ash layer was recovered in Section U1447A-12H-5. Diatoms are barren in these cores and nannofossil biostratigraphy indicates that the age of Core U1447A-38F is greater than 2.39 Ma; however, the biostratigraphy needs refinement.

Daily Science Report for 15 January 2015

Location: Hole U1447A (10°47.4052′N, 92°59.9996′E; 1390.9 m water depth)

Science Update: After a 709 nmi transit from Site U1446, the vessel arrived at Site U1447 (proposed site AA-2B) at 1430 h. The drill string and bottom-hole assembly were made up and 115 ft of drill line was cut off. Hole U1447A was spudded at 2320 h. Cores U1447A-1H to 10H (0–88.8 mbsf) have been retrieved with 104% core recovery.

Cores U1447A-1H to 6H contain greenish gray foraminfer-rich nannofossil ooze with clay and clay nannofossil ooze with foraminifers. A thick (106 cm) sandy bed composed of lithic material and shell fragments is found in Section U1447A-2H-1 and may be a large turbidite. A 6 cm thick ash bed is found in Section U1447A-3H-3 and plant debris is found in Core U1447A-6H. Authigenic nodules are found throughout the core. Foraminifers are well-preserved and nannofossil biostratigraphy indicates that the age of Core U1447A-10H is greater than 0.44 Ma.

Daily Science Report for 14 January 2015

Location: In transit to Site U1447 (proposed site AA-2B)

Science Update: The science laboratory teams continued to work on the Site U1445 and U1446 Reports. The Indian Monsoon scientists met to discuss the shipboard sampling plan for Site U1447. The vessel is scheduled to arrive at Site U1447 (proposed site AA-2B) at 1400 h on 15 January.

Daily Science Report for 13 January 2015

Location: In transit to Site U1447 (Proposed Site AA-2B)

Science Update: The science laboratory teams are working on the Site U1445 and U1446 Reports. The geochemical analyses for Site U1446 are complete. All of the archive half sections from Site U1446 have been run on the cryogenic magnetometer. Magnetic properties of the sediment show evidence of the diagenesis of iron-bearing minerals below ~30 m CSF-A in Hole U1446A. The vessel is scheduled to arrive at Site U1447 (Proposed Site AA-2B) at 1400 h on 15 January.

Daily Science Report for 12 January 2015

Location: In transit to Site U1447 (Proposed Site AA-2B)

Science Update: Cores U1446C-1H to 16H (0–149.4 mbsf) were retrieved with 98% core recovery. Cores U1446C-13H and 15H had 0% core recovery. Core U1446C-15H was re-shot from the same depth in an attempt to recover the previously cored interval. The second attempt retrieved 9.74 m of core. The HLAPC was deployed for Cores U1446C-17F to 23F (149.4–182.0 mbsf), which had 106% core recovery. At the end of coring operations, the hole was displaced with heavy mud. The pipe was pulled from the hole, clearing the seafloor at 1930 h. The vessel began the transit to primary site AA-2B (U1447) at 2400 h.

Cores U1446C-1H to 23F contain olive gray to gray biosilica-rich clay with nannofossils or foraminifers and clay with biosilica or nannofossils. The Toba ash is observed at ~15 m CSF-A. All of the physical property measurements for Site U1446 are complete and the majority of the geochemical analyses have been finished. The combined biostratigraphic and magnetostratigraphic datums indicate relatively constant, high sedimentation rates at Site U1446 over the past ~1 m.y.

Daily Science Report for 11 January 2015

Location: Hole U1446C (19°05.01′N, 85°44.09′E; 1430.1 m water depth)

Science Update: Cores U1446A-12H to 18H (99.3–165.8 mbsf) were retrieved with 107% core recovery. After three partial strokes using the APC system, the HLAPC was deployed for Cores U1446A-19F to 21F (165.8–180.0 mbsf), which had 103% core recovery. Temperature measurements were made on Cores U1446A-4H, 7H, 10H, and 15H. After coring operations the hole was displaced with heavy mud and drill pipe was pulled out of the hole. The pipe cleared the sea floor at 2105 h, the vessel was offset 20 m west, and Hole U1446B was spudded at 2150 h. Hole U1446B consists of three cores that were taken for high-resolution pore water sampling. Cores U1446B-1H to 3H (0–27.1 mbsf) were retrieved with 100% core recovery. The drill pipe was pulled from the hole and cleared the seafloor at 2325 h. The vessel was offset 20 m north and Hole U1446C was spudded at 0005 h on 12 January.

Cores U1446A-6H to 21F consist of greenish gray clay with nannofossils or biosilica and nannofossil-rich clay with foraminifers. Cores U1446B-1H to 3H consist of biosilica-rich clay with nannofossils. The Toba ash is observed in Hole U1446B. The Brunhes/Matuyama boundary (0.781 Ma) may have been identified within Core U1445A-15H. Nannofossil and diatom biostratigraphy indicates that the age of the base of Hole U1445A is 0.9–1.26 Ma.

Daily Science Report for 10 January 2015

Location: Site U1446 (19°05.01′N, 85°44.09′E; 1430.2 m water depth)

Science Update: The vessel completed the 97 nmi transit from Site U1445 to proposed site BB-7 (U1446) at 1614 h. Hole U1446A was spudded at 2225 h. Cores U1446A-1H to 11H (0–99.3 mbsf) have been retrieved with 102% core recovery.

Cores U1446A-1H to 5H contain olive gray to gray biosilica-rich clay with nannofossils or foraminifers. An ash layer (the Toba ash) and one turbidite are observed in Core U1446-3H. Nannofossil biostratigraphy indicates that Sample U1446A-12H-CC is greater than 0.44 Ma.

Daily Science Report for 9 January 2015

Location: In transit to proposed site BB-7 (U1446)

Science Update: Cores U1445C-25X to 36X (218.2–305.2 mbsf) were cut with 99% core recovery. After Core U1445C-36X was retrieved, the hole was displaced with heavy mud. Repairs were made to the hydraulic pump system on the iron roughneck before the drill string could be pulled from the hole. The drill pipe was tripped, the beacon recovered, and the vessel secured for transit to proposed site BB-7.

Cores U1445C-25X to 36X contain dark gray diatom-rich or biogenic-rich clay with glauconite. Few, thin turbidite beds are observed. Three thin (<5 cm) carbonate beds composed primarily of authigenic carbonate are found in Core U1445C-36X. The science laboratory groups have begun working on the U1445 Site Reports.

Daily Science Report for 8 January 2015

Location: Hole U1445C (17°44.72′N, 84°47.25′E, 2504.7 m water depth; proposed site BB-5)

Science Update: The day began with the re-stringing of the core winch cable and re-heading the sinker bars. Cores U1445C-10H to 12H (78.9–107.4 mbsf) were shot with the APC system. While retrieving Core U1445C-12H, the core winch cable parted ~530 m above the core barrel. The severed cable and core barrel were fished out of the drill string and a different core winch cable was installed. Coring continued with the APC system to Core U1445C-24H (218.2 mbsf). After recording partial APC strokes on Cores U1445C-23H and 24H, the XCB system was deployed. Temperature measurements were taken on Cores U1445C-20H and 22H.

Cores U1445C-10H to 24H contain dark gray nannofossil-rich and biosilica-rich clay. Few thin (<3 cm) turbidites are observed. Mousse-like core texture and thermal anomalies within the core indicate the presence of gas hydrates.

Daily Science Report for 7 January 2015

Location: Hole U1445C (17°44.72′N, 84°47.25′E, 2504.7 m water depth; proposed site BB-5)

Science Update: Following the downhole logging operations at Hole U1445A, the pipe was pulled out of the hole and the bit cleared the seafloor at 0711 h. The ship was offset 20 m to the south and Hole U1445B was spudded at 1010 h. Cores U1445B-1H to 4H (0–33.0 mbsf) were retrieved and several whole rounds were taken for high-resolution pore water geochemistry. The total core recovery for Hole U1445B is 101%. The pipe was pulled out of the hole and the bit cleared the seafloor at 1320 h. The vessel was offset 20 m to the west and Hole U1445C was spudded at 1415 h. Cores U1445C-1H to 9H (0–78.9 mbsf) were retrieved with 100% core recovery. At 2040 h, while recovering Core U1445C-9H, the core winch line parted. The day ended with the drill crew retrieving the core barrel and remaining cable.

Cores U1445B-1H to 4H and U1445C-1H to 9H were described. These cores contain dark gray clay with nannofossils or biosilica. Thin (<3 cm) turbidites composed of silty sand are observed. The biostratigraphers continue refining age datums for Hole U1445A. Sections U1445B-3H-1, 2, and 3 contain hydrogen sulfide.