IODP Expedition 361

Southern African Climates (Agulhas Current Density Profile APL)

Daily Science Report for 29 February 2016

Location: In transit to proposed Site ZAM-05A

Science Update: The drill string was pulled out of Hole U1475F with the bit clearing the seafloor at 0235 h, and it was back on the rig floor at 0800 h on 29 February. The seafloor positioning beacon was recovered at 0451 h. The rig floor was secured for transit, the thrusters were lowered, and the transit to proposed Site ZAM-05A began at 0930 h.

Cores U1475E-26H to 30H, U1475F-2H to 10H, and U1475D-1H to 3H are described and contain light greenish gray foraminifer-bearing nannofossil ooze alternating with nannofossil ooze with foraminifers and quartz. Moderate to strong bioturbation is found throughout the described interval. Pyrite and pyritized burrows are present. The micropaleontologists and palemagnetists are refining the site age model. A complete stratigraphic section was recovered from 0–75 mbsf and 185–255 mbsf. The stratigraphic correlation specialists continue to work on the interval between 75–185 mbsf.

Daily Science Report for 28 February 2016

Location: Hole U1475F (proposed site APT-01B, 41°25.6054′S, 25°15.6299′E, 2669.3 m water depth)

Science Update: Coring in Hole U1475E continued with the retrieval of Cores U1475E-26H to 30H (229.5–277.0 mbsf). The drill string was pulled out of the hole with the bit clearing the seafloor at 1335 h. The vessel moved 20 m west of Hole U1475B. Hole U1475F was spot-cored to recover stratigraphic gaps. Hole U1475F began at 1450 h and was washed down to 20 mbsf. Hole U1475F contained four drilled intervals (0–20.0 mbsf, 29.5–52.0 mbsf, 71.0–103.0 mbsf, and 112.5–114.5 mbsf). A total of six cores were recovered from selected intervals in Hole U1475F with 97% core recovery. After reaching 133.5 mbsf, the drill string was pulled out of the hole with the bit clearing the seafloor at 0235 h on 29 February.

Cores U1475E-1H to 25H (0–229.5 mbsf) were described. These cores contain light greenish gray foraminifer-bearing nannofossil ooze alternating with nannofossil ooze with foraminifers and quartz. Moderate to strong bioturbation is found throughout the described interval. Pyrite and pyritized burrows are present. Moderate to extreme coring disturbance is found in all of the cores, likely related to weather conditions. A complete stratigraphic record was recovered in Holes U1475C and U1475E from ~180 to 270 mbsf. Stratigraphic correlation from 0 to 180 mbsf is in progress.

Daily Science Report for 27 February 2016

Location: Hole U1475E (proposed site APT-01B, 41°25.6162′S, 25°15.6439′E, 2673.8 m water depth)

Science Update: After reaching 143.0 mbsf in Hole U1475D, the drill string was pulled from the hole. The bit cleared the seafloor at 0425 h. The vessel was offset 20 m south of Hole U1475A and Hole U1475E began at 0550 h. Cores U1475E-1H to 13H were taken to 119.0 mbsf. The hole was then deepened without coring from 119.0 to 125.5 mbsf to offset coring gaps for stratigraphic correlation. APC coring resumed and Cores U1475E-15H to 25H penetrated from 125.5 to 229.5 mbsf.

Cores U1475C-23H to 30H (199.0–275.0 mbsf) contain light greenish-gray nannofossil ooze with foraminifers and quartz. Moderate to strong bioturbation and pyrite are observed throughout the described interval. Carbonate content in Hole U1475B sediments are 75%–85% except for values of ~90% at the top of the hole. Hole U1475E cores are being processed before those from Hole U1475D so that RGB and light reflectance can be gathered for stratigraphic correlation. The Geochemistry Laboratory team completed squeezing the high-resolution interstitial water samples from Hole U1475D.

Daily Science Report for 26 February 2016

Location: Hole U1475D (proposed site APT-01B, 41°25.6055′S, 25°15.6586′E, 2668.3 m water depth)

Science Update: Cores U1475C-29H and 30H (256.0–275.0 mbsf) were retrieved with 105% core recovery. The drill string was pulled from the hole and the bit cleared the seafloor at 0935 h, ending Hole U1475C. The vessel was offset 20 m east of Hole U1475A and Hole U1475D began at 1155 h. Sixteen cores were taken over a 143.0 m interval with 105% core recovery. Interstitial water samples were collected at 1.5 m resolution over the entire interval for postcruise analysis.

Cores U1475C-1H to 22H were described. Core U1475C-1H contains pale brown foraminifer-rich nannofossil ooze at the top of the section (0–0.25 mbsf). The remainder of Core U1475C-1H through 7H (0.25–66.5 mbsf) contains alternating layers of light gray nannofossil ooze with fine quartz sand and light greenish gray foraminifer-bearing nannofossil ooze. Two individual quartz pebbles are found in Cores U1475C-1H and 5H, which are indicative of ice rafted debris during glacial climates. Cores U1475C-8H to 16H (66.5–148.5 mbsf) contain light greenish gray nannofossil ooze with foraminifers, quartz, and diatoms. Moderate to strong bioturbation is found throughout the described section and pyritized burrows are observed. Cores U1475C-1H to 5H (0–47.5 mbsf) have low magnetic intensity but interpretable magnetic inclination. The Brunhes/Matuyama boundary (0.781 Ma) is found at the top of Core U1475-3H and an interval of normal polarity, which may be the Olduvai, is found in Core U1475-5H. The Geochemistry Laboratory team is processing the interstitial water samples taken in Hole U1475D.

Daily Science Report for 25 February 2016

Location: Hole U1475C (proposed site APT-01B, 41°25.5941′S, 25°15.6439′E, 2669.3 m water depth)

Science Update: After ending Hole U1475B at 0430 h, the vessel was offset 20 m north and Hole U1475C was begun at 0625 h. Cores U1475C-1H to 28H (0–256.0 mbsf) were retrieved with 103% core recovery.

Cores U1475B-12H to 26H contain greenish-gray nannofossil ooze with foraminifera and quartz. There is moderate bioturbation throughout these cores and pyritized burrows are observed. Drilling disturbance is prevalent in the first section of each of the cores. Paleomagnetic intensity is low but some changes in inclination are observed that are likely paleomagnetic reversals. Sample U1475C-28H-CC is ~6 Ma in age based on planktonic foraminifer biostratigraphy.

Daily Science Report for 24 February 2016

Location: Hole U1475B (proposed site APT-01B, 41°25.6052′S, 25°15.6441′E, 2669.4 m water depth)

Science Update: Hole U1475B was APC cored to 243.0 mbsf. After retrieving Core U1475B-26H the drill string was pulled from the hole and the bit cleared the seafloor at 0430 h on 25 February, ending Hole U1475B. A total of 250.31 m of sediment was recovered over a 243.9 m cored interval in Hole U1475B (103%).

Cores U1475B-1H to 11H (0 to 101.4 m) were described. Core U1475B-1H contains brown silty clay with foraminifers at the very top of the section (0–0.4 m). The remainder of Core U1475B-1H through 9H (0.4–82.58 m) contains alternating layers of light gray nannofossil ooze with fine quartz sand and light greenish gray foraminifer-bearing nannofossil ooze. Cores U1475B-10H and 11H contain light greenish gray foraminifer-bearing nannofossil ooze with diatoms. Bioturbation is moderate throughout and drilling disturbance is observed in the first section of most of the cores. Foraminifers are moderately to well preserved and fragmentation increases downhole. Calcareous nannofossil are moderately preserved. Calcareous microfossil biostratigraphy indicates that the base of Hole U1475B is ~5.3 to 5.5 Ma in age (late Miocene).

Daily Science Report for 23 February 2016

Location: Site U1475 (proposed site APT-01B, 41°25.6052′S, 25°15.6440′E, 2669.4 m water depth)

Science Update: The vessel arrived at Site U1475 on the afternoon of 23 February. The thrusters were lowered at 1533 h and the beacon was deployed at 1545 h. The drill string was constructed with an APC/XCB bottom-hole assembly. Hole U1475A began at 0238 h on 24 February. Core U1475A-1H contained 1.5 m of sediment and Hole U1475A was abandoned so that a longer mudline core could be recovered. Hole U1475B was begun at 0332 h. Thus far, Cores U1475A-1H (0 to 1.5 m) and U1475B-1H to 4H (0 to 34.9 m) were taken with over 100% sediment recovery.

Core U1474A-1H contains brown nannofossil-bearing clay with foraminifers, light gray clayey foraminifer ooze with nannofossils, and greenish gray clayey nannofossil ooze with foraminifers. There is little variation in the magnetic susceptibility, gamma ray attenuated bulk density, and natural gamma radiation measurements; however, the spectral reflectance data show potential orbital-scale variations. Calcareous microfossils are well-preserved and diatoms are present. Nannofossil biostratigraphy indicates that Sample U1475B-4H-CC is within Zone NN19 and has an approximate age of 1 Ma.

Daily Science Report for 22 February 2016

Location: In transit to proposed Site APT-01B (U1475)

Science Update: The science laboratory teams worked on revising their Site U1474 reports and attended the Site U1475 pre-site meeting. The vessel is underway to Site U1475 and is scheduled to arrive at 1530 h on 23 February.

Daily Science Report for 21 February 2016

Location: In transit to proposed Site APT-01B (U1475)

Science Update: The vessel began the day in transit towards Port Elizabeth, South Africa, for a medical evacuation. The evacuation was successfully completed at 1230 h. The vessel changed course and began the transit to proposed Site APT-01B. The ship is estimated to be on site at 1200 h on 23 February. The science laboratory teams submitted their Site U1474 Reports and learned about pore water nitrate.

Daily Science Report for 20 February 2016

Location: In transit to Port Elizabeth, South Africa, for a medical evacuation

Science Update: The science laboratory teams continue to work on their Site U1474 reports. A talk was given to the science party about ocean stratification during glacial and interglacial intervals. The ship is scheduled to meet a helicopter for a medical evacuation at 1230 h on 21 February.

Daily Science Report for 19 February 2016

Location: In transit to proposed Site APT-01B (U1475)

Science Update: All of the cores and samples from Site U1474 have been processed. The science laboratory teams presented their site results and continue to work on their site reports. On the morning of 20 February the decision was made to divert course to Port Elizabeth, South Africa, for a medical evacuation.

Daily Science Report for 18 February 2016

Location: In transit to proposed Site APT-01B (U1475)

Science Update: The drill string was pulled out of Hole U1474F. The bit cleared the seafloor at 0040 h and cleared the rotary table at 0745 h. The rig was then secured for transit. The beacon was recovered at 0905 h and the thrusters were raised at 0945 h. The vessel began the transit to proposed Site APT-01B at 0948 h, ending Hole U1474F and Site U1474. The ship is estimated to arrive on site at 0200 h on 21 February.

Cores U1474F-29F to 33F were described and contain greenish gray nannofossil-rich clay with foraminifera. The cores are moderately bioturbated and show some diagenetic alteration. Approximately one to two, centimeter-scale, quartz-rich sand layers are present in each core. A complete stratigraphic splice was recovered at Site U1474 that extends to ~5.3 Ma. The science laboratory teams continue to work on the Site U1474 reports.

Daily Science Report for 17 February 2016

Location: Hole U1474F (proposed site NV-02C, 31°13.0105′S, 31°32.7078′E, 3035.9 m water depth)

Science Update: Cores U1474F-19H to 21H (164.7 to 190.2 mbsf) were retrieved using the APC system. After experiencing partial strokes while taking Cores U1474F-20H and 21H, the half-length APC (HLAPC) system was deployed for Cores U1474F-22F to 24F (190.2 to 204.3 mbsf). Following Core U1474F-24F the stratigraphic correlators requested a 2.0 m drilled interval (U1474F-251) to offset the coring gaps. Coring operations with the HLAPC continued through Core U1474F-33F where APC refusal depth was reached at 238.4 mbsf. The drill string was pulled out of the hole and the bit cleared the seafloor at 0400 h on 18 February. A total of 241.3 m of sediment was recovered over a 236.4 m cored interval (102%) in Hole U1474F.

Cores U1474F-12H to 28F contain greenish gray nannofossil-rich clay with foraminifera. The cores are moderately bioturbated and show some diagenetic alteration. Approximately one to two, centimeter-scale, quartz-rich sand layers are present in each core. The science laboratory teams are processing the remaining cores from Hole U1474F and are composing their site reports.

Daily Science Report for 16 February 2016

Location: Hole U1474F (proposed site NV-02C, 31°13.0105′S, 31°32.7078′E, water depth 3035.9 m)

Science Update: After recovering Core U1474E-19F, the drill string was pulled out of the hole. The bit cleared the seafloor at 0630 h, ending Hole U1474E. The final depth of Hole U1474E was 219.0 mbsf. The vessel was offset 20 m south of Hole U1474A and coring in Hole U1474F started at 0845 h. Cores U1474F-1H to 18H (0–164.7 mbsf) were retrieved with 100% core recovery.

Cores U1474E-13F to 19F contain greenish gray nannofossil-rich clay with foraminifera. The cores are moderately bioturbated and show some diagenetic alteration. Approximately one to two sand layers are present in each core. A ~50 cm layer of brown foraminifer-bearing clay is found at the top of Core U1474F-1H. The remainder of Core U1474F-1H and Cores U1474F-2H to 11H contain bioturbated greenish gray nannofossil-rich clay with intermittent sandy layers. A complete stratigraphic splice to 202 mbsf has been recovered using data from all of the holes at this site. The total organic carbon content is less than 0.5% throughout Hole U1474A. Carbonate percent varies between 20%–60% with an average of 39%.

Daily Science Report for 15 February 2016

Location: Hole U1474E (proposed site NV-02C, 31°12.9995′S, 31°32.7208′E, water depth 3034.4 m)

Science Update: Hole U1474E was spudded 20 m east of Hole U1474A at 0725 h. The hole was drilled without coring to 105.5 m. Cores U1474E-2H to 9H were recovered using the APC system to 172.0 m with 105% core recovery. One drilled interval between 124.5 and 126.0 mbsf was used to aid in stratigraphic correlation. The half-length APC (HLAPC) was deployed for Cores U1474E-10F to 19F (172.0–219.0 mbsf) and yielded 99% core recovery.

Cores U1474E 2H to 12F contain greenish gray nannofossil-rich clay with foraminifera. The cores are moderately bioturbated and show some diagenetic alteration. Approximately one to two sand layers are present in each core. Thus far, a complete stratigraphic section has been recovered to ~190 mbsf. All of the moisture and density samples have been analyzed and the Geochemistry Laboratory has completed measuring most of their samples.

Daily Science Report for 14 February 2016

Location: Hole U1474D (proposed site NV-02C, 31°12.9999′S, 31°32.7213′E, water depth 3034.4 m)

Science Update: Early on 14 February, winds picked up to 50 kt with gusts up to 58 kt. Between the wind and the 2 kt current, the vessel had difficulty maintaining position over Hole U1474D. The drill string was pulled out of the hole and the bit cleared the seafloor at 0305 h, ending Hole U1474D. The final depth of Hole U1474D was 124.5 m. The vessel drifted at 0.9 kt towards the south. The entire drill string was tripped while waiting on the weather. At 1900 h the thrusters were raised to transit back to Site U1474. The thrusters were lowered at 2003 h after regaining position over the site. The day ended with the drill string being assembled in preparation for spudding Hole U1474E.

Cores U1474D-8H to 14H were described. These cores contain greenish gray nannofossil-rich clay with foraminifera. These cores are moderately bioturbated and show some diagenetic alteration. Approximately one to two sand layers are present in each core. The stratigraphic correlators have determined that we have recovered a complete stratigraphic sequence to 124.5 m. The Geochemistry Laboratory team is in the process of running all of their analyses from Holes U1474A and U1474B.

Daily Science Report for 13 February 2016

Location: Hole U1474D (proposed site NV-02C, 31°12.9999′S, 31°32.7213′E, water depth 3034.4 m)

Science Update: After retrieving Core U1474B-16H the drill string was pulled out of the hole. The bit cleared the seafloor at 0835 h, ending Hole U1474B. The vessel was offset 20 m east and Hole U1474C was spudded at 0935 h. Core U1474C-1H was recovered with 3.07 m of sediment. The stratigraphic correlators decided that a longer first core needed to be recovered to fill in stratigraphic gaps and Hole U1474C was terminated. Hole U1474D was spudded at 1100 h. Cores U1474D-1H through 14H (0 to 124.5 mbsf) were retrieved with 93% core recovery.

Cores U1474B-10H to 16H, U1474C-1H, and U1474D-1H to 8H were described. Cores U1474C-1H and U1474D-1H contain brown foraminifer-bearing clay. The other cores described are light to dark gray nannofossil-rich clay with foraminifera. These cores are moderately bioturbated and show some diagenetic alteration. Small, centimeter-scale turbidites are present. The extinction of the benthic foraminifer genus Stilostomella, dated between 0.6 and 1.0 Ma, is found in Core U1474A-4H near the Brunhes-Matuyama magnetic reversal (0.78 Ma). The micropaleontologists and paleomagnetists continue to refine the shipboard stratigraphy. All of the whole rounds taken from Hole U1474B for interstitial pore water analysis have been squeezed.

Daily Science Report for 12 February 2016

Location: Hole U1474B (proposed site NV-02C, 31°12.9882′S, 31°32.7083′E, water depth 3034.4 m)

Science Update: Core U1474A-27H was recovered with 8.97 m of sediment, of which 3.97 m was determined to be flow-in. The Half-Length Advanced Piston Corer (HLAPC) was deployed for Cores U1474A-28F to 29F (244.9–254.1 mbsf) and recovered 8.72 m of sediment. The decision was made to terminate Hole U1474A after Core U1474A-29F. The drill string was pulled out of the hole and the bit cleared the seafloor at 1040 h, ending Hole U1474A. The vessel was offset 20 m north and APC coring in Hole U1474B started at 1320 h. Cores U1474B-1H to 16H were recovered from the seafloor to 147.30 mbsf with 96% core recovery. At least one whole-round sample for interstitial water analyses was taken from every core section in Hole U1474B.

The final cores from Hole U1474A (21H–29H) contain light to dark gray nannofossil-rich clay with foraminifera. These cores are moderately bioturbated and show some diagenetic alteration. Small, centimeter-scale turbidites are present. Hole U1474A is divided into two distinct lithologic units: brown foraminifer-bearing clay that overlies the above mentioned gray nannofossil-rich clay containing turbidites. The same lithologies are recognized in Cores U1474B-1H to 9H. Nannofossil and planktic foraminifer biostratigraphy indicate that the age of the base of Hole U1474A is ~6.1 Ma. The Geochemistry Laboratory team is processing the high-resolution pore water samples from Hole U1474B.

Daily Science Report for 11 February 2016

Location: Hole U1474A (proposed site NV-02C, 31°12.9995′S, 31°32.7080′E, water depth 3033.8 m)

Science Update: While retrieving Core U1474A-10H the core line frayed and became stuck. The line was repaired and coring operations resumed. Cores U1474A-11H to 26H were recovered from 90.90 to 239.90 mbsf with 103% core recovery.

Cores U1474A-5H to 20H consist of light to dark gray nannofossil-rich clay with foraminifers. These cores are moderately bioturbated and show some diagenetic alteration. Centimeter-scale turbidites are present at a frequency of 1 to 2 per core. The Olduvai magnetic reversal (1.778 Ma) is observed in Core U1474A-8H and the Gauss reversal (2.581 Ma) is found in Core U1474A-12H. Foraminifer preservation is degrading down hole and planktic foraminifer biostratigraphy indicates that Sample U1474A-25H-CC is in Zone PL1/M14. Calcareous nannofossil biostratigraphy places Sample U1474-26H-CC in Zone NN11 with an age of ~6 Ma (late Miocene).

Daily Science Report for 10 February 2016

Location: Hole U1474A (proposed site NV-02C, 31°12.9993′S, 31°32.7080′E, water depth 3033.8 m)

Science Update: The vessel arrived at Site U1474 at 2330 h on 9 February. At 0342 h the beacon was deployed. The bottom-hole assembly was made-up and the drill string was assembled. The first core was shot using the advanced piston coring system and recovered a full core barrel. The bit was raised 8 m and a second attempt was made at recovering the mudline; this core barrel was also full. The bit was raised another 5 m and Hole U1474A was successfully spudded at 1525 h. Thus far we have retrieved Cores U1474A-1H to 10H to a depth of 90.90 mbsf with a recovery of 102%.

Cores U1474A-1H to 4H contain light to dark gray foraminifer-bearing clay, foraminifer-bearing clay with nannofossils, and nannofossil ooze. Centimeter-scale turbidites are observed at a frequency of 1–2 per core and manganese nodules are present. The cores display slight to moderate bioturbation and diagenetic alteration. Cores U1474A-1H to 3H are within the Brunhes chron. Nannofossil and planktic foraminifer biostratigraphy indicate that Sample U1474-10H-CC is ~2.1 Ma in age (early Pleistocene). The benthic foraminifer assemblage is characteristic of a low-oxygen environment.

Daily Science Report for 9 February 2016

Location: Site U1474 (NV-02C, 31°12.9993′S, 31°32.7080′E)

Science Update: The science laboratory teams finalized their preparations for processing cores and completed the first draft of their Methods chapters. The micropaleontologists and sedimentologists were trained to use the desktop scanning electron microscope, while the physical properties team learned how to run the whole round tracks and process moisture and density samples. The geochemists, chemistry technician, Curator, and Co-Chief Scientists met to discuss the workflow for the high-resolution pore water sampling that will take place while at Site U1474. We had a science presentation on dust transportation and Indian Monsoon intensity over the past 60 k.y. using lake records from China.

The vessel arrived at Site U1474 at 2330 h and lowered the thrusters.

Daily Science Report for 8 February 2016

Location: In transit to Site U1474 (NV-02C)

Science Update: The Operations Superintendent led a tour of the ship for another group of scientists. The entire science party met to converge on a sampling plan for shipboard measurements and the Core Description team discussed core flow within the core laboratory. The Education Officer presented the education and outreach plans for the expedition. We held a pre-spud meeting to review the operations for Site U1474. The ship is estimated to arrive at Site U1474 at 2400 h on 9 February.

Daily Science Report for 7 February 2016

Location: In transit to Site U1474 (NV-02C)

Science Update: The science laboratory teams gave an overview of their shipboard methodology to the entire science party. The Co-Chief Scientists presented an introduction of the expedition science to the ship’s crew and IODP technical staff. The Operations Superintendent led a tour of the ship for some of the scientists. Finally, we held a meeting to discuss postcruise research related to terrestrial proxies.

The ship is estimated to arrive at Site U1474 at 2300 h on 9 February.

Daily Science Report for 6 February 2016

Location: In transit to Site U1474 (NV-02C)

Science Update: The science party and new IODP technical staff were given a ship security overview and shown where their safe rooms are. We had meetings to discuss interstitial water splits and postcruise XRF core scanning. The micropalentologists were given an introduction to the program BugWin. The Operations Superintendent led a tour of the ship for some of the scientists.

Diplomatic clearance for operating in Mozambique waters is pending. The decision was made to alter the initial operations plan and proceed to proposed site NV-02C which is located in South African waters.

Daily Science Report for 5 February 2016

Location: In transit to Site U1474 (MZC-01C)

Science Update: Both science shifts were trained to use SampleMaster, the sample input and uploading system on the ship. The science party was given a presentation on recent research done in the Natal Valley off of South Africa. Science laboratory teams continued to work on their Methods chapters. The vessel is estimated to arrive at Site U1474 (MZC-01C) at 0800 h on 10 February.

Daily Science Report for 4 February 2016

Location: In transit to Site U1474 (MZC-01C)

Science Update: The vessel departed Port Louis, Mauritius, with the last line away at 0736 h. The pilot disembarked the JOIDES Resolution at 0808 h and the ship began the sea transit at 0812 h. The vessel is estimated to arrive at Site U1474 (MZC-01C) at 0800 h on 10 February.

The first abandon ship drill of the expedition was held in the morning. The Core Description and Micropaleontology teams were given a core flow tour, and the core describers defined an initial template for the visual core description sheets. We had a brief science meeting to update the science party on the schedule of activities during the transit. The science laboratory teams continued to work on their Methods chapters.