IODP Expedition 349

South China Sea Tectonics

Daily Science Report for 29 March 2014

LOCATION: Underway to Keelung, Taiwan

SCIENCE UPDATE: We held the final science meeting of the expedition to discuss the overall results and expedition achievements. Scientists finalized the remaining site reports. We expect to be at the pilot station at 0700 h on Sunday, 30 March.

Daily Science Report for 28 March 2014

LOCATION: Underway to Keelung, Taiwan

SCIENCE UPDATE: We held a science meeting for the scientists to present the final results from Site U1435. The scientists also worked on writing and finalizing the final site reports. The technical staff began cleaning the laboratory areas. We expect to arrive in Keelung early in the morning on Sunday, 30 March.

Daily Science Report for 27 March 2014

LOCATION: Underway to Keelung, Taiwan

SCIENCE UPDATE: We cut and recovered Cores U1435A-30R through ‑32R (278.5–300.0 mbsf), with the last core of the expedition on deck at 0830 h. We then tripped to the surface and secured the vessel for transit, departing for Keelung at 1900 h.

Cores U1435A-20R through ‑32R were split and described. Cores U1435A-20R through ‑29R consist primarily of dark gray sandstone, silty sandstone, and sandy siltstone. Shell fragments are common throughout and occasional whole bivalve and gastropod shells occur toward the bottom of the section. This interval is heavily bioturbated, with large vertical and horizontal burrows that are typical of shallow marine environments. Cores U1435A-30R to ‑32R are finer grained, with black silty mudstone interbedded with the gray sandstone. The mudstones are sometimes laminated. Pyrite is found throughout the described interval. Geochemistry and physical properties measurements on discrete samples for this hole are ongoing.

Daily Science Report for 26 March 2014

LOCATION: Hole U1435A (18°33.3466′N, 116°36.6174′E; water depth 3253 m)

SCIENCE UPDATE: We cut and recovered Cores U1435A-18R through ‑29R (162.1–278.5 mbsf). Core recovery was generally excellent over this interval, with the exception of Core U1435A-22R, which only recovered 0.19 m of rock. Average recovery for these 12 cores was 84%. Calcareous nannofossils and radiolarians are barren over the interval cored. A few benthic foraminifers that indicate deposition in a very shallow marine to brackish water environment were found in two cores.

Cores U1435A-10R to ‑19R were split and described. This interval consists of dark gray silty sandstone and gray sandstone. There are some intervals with parallel and cross laminations. The sand is composed of quartz, feldspar, volcanic glass, and calcite grains. Black wood fragments occur throughout. Shell fragments and pyrite are also present in Core U1435A-15R and below. Some intervals are heavily bioturbated and include large horizontal and vertical burrows typical of shallow marine environments.

Daily Science Report for 25 March 2014

LOCATION: Hole U1435A (18°33.3466′N, 116°36.6174′E; water depth 3253 m)

SCIENCE UPDATE: We spudded Hole U1435A at 0035 h. Cores U1435A-1R through ‑17R were cut and recovered using the RCB system (0–162.1 mbsf). Core recovery was very poor (<5%) in the top four cores and then improved below that as we encountered stiffer sediments. Average recovery over the cored interval was 41%. Cores U1435A-2R and ‑3R are Middle to Late Pleistocene and Cores U1435A-4R to ‑9R are early to late Oligocene in age based on biostratigraphy. Below Core U1435A-9R, cores are barren of nannofossils, foraminifers, and radiolarians.

Cores U1435A-3R through ‑9R were split and described. The very small amount of sediment recovered in Cores U1435A-3R and ‑4R consists of nannofossil-rich clay and foraminifer-rich nannofossil ooze. A couple of manganese nodules were found in these cores. The Oligocene sediments of Cores U1435A-5R to ‑9R are composed of greenish gray silty clay and nannofossil-rich clay. These cores are strongly disturbed by drilling, making it difficult to identify sedimentary structures, although Chondrites and Planolites trace fossils are present. Minor pyrite also occurs throughout this interval.

Daily Science Report for 24 March 2014

LOCATION: Hole U1435A (18°33.3466′N, 116°36.6174′E; water depth 3253 m)

SCIENCE UPDATE: We arrived at Site U1435 (proposed site SCS-6C) at 1524 h and made up an RCB bottom hole assembly and began to trip pipe toward the seafloor. While tripping pipe, we conducted a survey using the 3.5 kHz sonar to select a location where there appeared to be thicker sediment above basement, which was predicted at only ~10 mbsf. At the end of the day we were preparing to spud Hole U1435A.

The scientists presented final results from Site U1434. The sediment and rock recovered between 197.0 and 312.5 mbsf is divided into four lithostratigraphic units. Lithostratigraphic Unit I consists of interbedded dark greenish gray claystone and black volcaniclastics. Unit II contains fewer volcaniclastic units, with nannofossil- and foram-rich claystones. Unit III consists of yellow brown claystone that overlies the basalts of Unit IV. The sediments are dated to the middle to late Miocene. The basalts are divided into seven igneous lithologic units. Five of these units are aphanitic aphyric pillow basalts with traces of olivine and a groundmass primarily composed of microlites of plagioclase. The other two units are hyaloclastite breccias.

Daily Science Report for 23 March 2014

LOCATION: In transit to Site U1435 (proposed site SCS-6C)

SCIENCE UPDATE: The petrologists finished describing the approximately 3 m of basalt recovered from Cores U1434A-10R through ‑15R (~278–309 mbsf), which consists of aphanitic aphyric pillow basalts with traces of olivine. The groundmass is composed primarily of microlites of plagioclase, with mesostasis in between. In addition to the pillows, a few hyaloclastite breccias were recovered. The phase assemblage in these rocks is typical of mid-ocean ridge basalts; however, we are awaiting geochemical analysis to confirm this interpretation.

We held a science meeting to discuss the end-of-expedition schedule and what happens after the expedition. The staff scientist presented the schedule for finalizing analyses and reports for the last two sites. We also briefly discussed the first and second post-cruise meetings, as well as data access and publications during the moratorium. Scientists continued to revise Site U1433 reports and write Site U1434 reports.

Daily Science Report for 22 March 2014

LOCATION: In transit to Site U1435 (proposed site SCS-6C)

SCIENCE UPDATE: Cores U1434A-13R to ‑14R were cut and recovered (298.1–307.7 mbsf), with 10% recovery each. Excessive torque and overpull were noted while coring this interval. After retrieving Core U1434A-14R, we completed a 25 barrel sweep and reamed the existing hole for 75 min. With weather and hole conditions continuing to deteriorate, we decided to terminate Hole U1434A after Core U1434A-15R (307.7–312.5 mbsf) recovered only 0.71 m of core (15%). After spending approximately 90 min working the pipe that had become stuck in the bottom of the hole, we tripped to the surface and secured the rig floor for transit, departing for Site U1435 at 2348 h.

Cores U1434A-11R through ‑15R were split, sampled for shipboard analyses (thin section and inductively coupled plasma-atomic emission spectroscopy (ICP-AEC]), digitally imaged, and scanned for magnetic susceptibility and color reflectance. Macroscopic description of these basalts is ongoing. We held the final Site U1433 science meeting, with results presented by all lab groups. Scientists continued to finalize the Site U1433 reports and also began drafting Site U1434 reports.

Daily Science Report for 21 March 2014

LOCATION: Hole U1434A (13°11.5080′N, 114°55.4005′E; water depth 4009 m)

SCIENCE UPDATE: Cores U1434A-2R through ‑12R (197.0–298.1 mbsf) were cut and recovered. We penetrated into basalt in Core U1434A-10R at approximately 278 mbsf. Recovery in the sediment section in Cores U1434A-2R through ‑10R averaged 27%. The two basalt cores (U1434A-11R and ‑12R) averaged only 9% recovery. The interval from Cores U1434A-2R through ‑9R ranges in age from ~6.5 to 9 Ma (late Miocene) based on calcareous nannofossil and planktonic foraminifer biostratigraphy.

Cores U1434A-2R through ‑10R were split and described. Cores U1434A-2R through ‑4R consist of dark greenish gray claystone and black to gray sandstone. The dark color of the sandstone grains suggests a volcanic source, likely the nearby seamount. The claystones are color banded and heavily bioturbated. The volcanic sandstone disappears downhole, with Cores U1434A-5R through ‑7R primarily dominated by greenish gray nannofossil-rich claystone. The claystone color changes to brown and yellowish brown in Cores U1434A-8R through ‑10R, with foraminifers abundant near the base of the section.

Daily Science Report for 20 March 2014

LOCATION: Hole U1434A (13°11.5080′N, 114°55.4005′E; water depth 4009 m)

SCIENCE UPDATE: We arrived at Site U1434 at 0048 h and prepared the rotary core barrel (RCB) bottom hole assembly. We then tripped pipe to the seafloor and spudded Hole U1434A at 1215 h. We drilled down to 197.0 mbsf, retrieved the center bit, dropped a core barrel, and were preparing to begin coring operations at the end of the day.

The scientists continued remaining analyses for Site U1433 and also worked on site reports and presentations for the final Site U1433 science meeting. The core description group defined four lithostratigraphic units for Site U1433. Lithostratigraphic Unit I consists of Pleistocene clays, with minor amounts of silt and carbonate turbidites. Unit II includes middle Miocene to Pleistocene clays and carbonate turbidites, with two subunits distinguished on the basis of carbonate turbidite thickness. Unit III consists of lower to middle Miocene claystones that are primarily reddish brown in color. Unit IV is composed of basalt. Biostratigraphic and paleomagnetics results are in good agreement for this site and show very low sedimentation rates in the claystones above basement (Unit III), rates varying between 5 and 9 cm/k.y. for Unit II, and higher rates (~20 cm/k.y.) for Unit I. A paleomagnetic reversal has also been identified in the basement section.

Daily Science Report for 19 March 2014

LOCATION: In transit to Site U1434 (proposed site SCS-4E)

SCIENCE UPDATE: We logged Hole U1433B with the FMS-sonic tool string, completing multiple passes through the basement section and one pass through the sediment section. After rigging down from logging, the rig floor was secured, the thrusters raised, and we departed for Site U1434 (proposed site SCS-4E).

The petrologists and structural geologists described the remainder of the Hole U1433B basalt cores. The basement consists of 44 units, with the number of massive flow units increasing downhole. Alteration is heaviest in the upper part of the basement. Thin section examination and analysis of basalt samples by inductively coupled plasma–atomic emission spectroscopy (ICP-AES) is ongoing. Other lab groups worked to finish analyses on the Site U1433 cores and began writing up results. We also completed sampling of the basement from Site U1431 for post-expedition research.

Daily Science Report for 18 March 2014

LOCATION: Hole U1433B (12°55.1313′N, 115°2.8484′E; water depth 4379 m)

SCIENCE UPDATE: We completed a wiper trip over the basement section of the hole and pumped a 50 barrel high viscosity mud sweep to clean the hole in preparation for logging. We then attempted to release the bit with the rotary shifting tool (RST); however, the RST backed off the upper threaded connection. After making up a fishing tool, the bit (and RST) were successfully dropped in the bottom of the hole. After shifting the mechanical bit release back into the down position, the end of the pipe was raised to 689.1 mbsf and the hole displaced with 225 barrels of 10.5 ppg mud. The end of pipe was then set at 100.1 mbsf for logging and the triple combo tool string run in the hole to 845.4 mbsf. We successfully completed one upward pass with the triple combo and were preparing to deploy the FMS-sonic tool string at the end of the day.

Cores U1433B-61R to ‑64R were split and described. These cores consist of varying shades of reddish to yellowish brown claystone, with a few dark greenish gray color bands. Pyrite nodules occur occasionally. Calcareous microfossils are absent throughout most of this interval; however, radiolarians are present in a few samples and indicate an early to middle Miocene age.

The remainder of the basalt cores (U1433B-69R to ‑75R) were also split, imaged with the section half image logger, and scanned for color reflectance and magnetic susceptibility. Description of these cores is ongoing. Numerous pillow lava units, characterized by glassy margins, occur in the upper part of the basement section, with the number of massive flow units increasing downhole.

Daily Science Report for 17 March 2014

LOCATION: Hole U1433B (12°55.1313′N, 115°2.8484′E; water depth 4379 m)

SCIENCE UPDATE: Cores U1433B-70R through ‑75R (829.4–858.5 mbsf) were cut and recovered. These cores were half cores (4.8 or 4.9 m advance), with an average recovery of 46%. We decided to terminate the hole after retrieving Core U1433B-75R due to very low (<1 m/h) penetration rates in order to begin preparations for downhole logging.

Cores U1433B-50R to ‑60R were split and described. This interval is dominated by claystone and nannofossil chalk. The claystone is typically dark greenish gray, occasionally dark reddish gray, and color banded. The nannofossil chalks often have foraminiferal chalks at their base and grade upward, indicative of turbidite deposition. Minor interbeds of siltstone also occur over this interval. Bioturbation is usually heavy, particularly in the tops of the nannofossil chalks.

Cores U1433B-66R to ‑68R were also split and described by the petrologists and structural geologists. These rocks are primarily plagioclase-phyric basalts with traces of olivine in a very fine-grained matrix that consists mostly of glass or altered glass. This interval consists of several pillow units, as well as one massive flow unit (3–4 m thick).

Daily Science Report for 16 March 2014

LOCATION: Hole U1433B (12°55.1313′N, 115°2.8484′E; water depth 4379 m)

SCIENCE UPDATE: Cores U1433B-67R through ‑69R (814.9–829.4 mbsf) were cut and recovered, with an average recovery of 54%. We began taking half cores over this interval to improve recovery.

Cores U1433B-41R to ‑49R were split and described. Nannofossil chalk is more abundant throughout this interval, with some beds of foraminiferal chalk grading upward into nannofossil chalk. Dark greenish gray and dark gray or dark reddish gray claystone become more abundant downcore. Bioturbation is common throughout much of the section, with well-developed burrows present in the tops of the nannofossil chalks. Core U1433B-65R was also split, as this core contains the sediment/basement interface. The basalts are heavily altered and some green mudstone was found amongst the pillows. Biostratigraphic analysis of this mudstone is ongoing.

Daily Science Report for 15 March 2014

LOCATION: Hole U1433B (12°55.1313′N, 115°2.8484′E; water depth 4379 m)

SCIENCE UPDATE: Cores U1433B-57R to ‑66R (717.9–811.7 mbsf) were cut and recovered. Core recovery was very good over this interval, averaging 80%. A distinct color change to brownish clay occurs in Core U1433B-60R. We then encountered basalt in Core U1433B-65R at a depth of approximately 800 mbsf. Calcareous nannofossil and planktonic foraminifer biostratigraphy indicate a late Miocene age for the greenish gray lithologies of Cores U1433B-57R to ‑59R. Calcareous microfossils are very poorly preserved or absent in the brownish clays; however, radiolarians are present in some samples and indicate an early to middle Miocene age.

Cores U1433B-30R through ‑40R were split and described. This interval is dominated by dark greenish gray claystone and light greenish gray nannofossil chalk. There are also a few interbeds of nannofossil-rich claystone, foraminifer-rich nannofossil chalk, and foraminiferal chalk. The claystones are generally heavily bioturbated. The cores are strongly affected by biscuiting drilling disturbance.

Daily Science Report for 14 March 2014

LOCATION: Hole U1433B (12°55.1313′N, 115°2.8484′E; water depth 4379 m)

SCIENCE UPDATE: Cores U1433B-44R to ‑56R (591.8–717.9 mbsf) were cut and recovered. Core recovery averaged 54% over this interval. Calcareous nannofossil and planktonic foraminifer biostratigraphy indicate an age of <9 Ma (late Miocene) for the base of the recovered section.

Cores U1433B-20R through ‑29R were split and described. These sediments consist of alternating layers of dark greenish gray clay and light greenish gray nannofossil ooze. A few intervals of foraminiferal ooze are also present. Bioturbation is heavy throughout. The sediments become more strongly consolidated to weakly lithified toward the base of the split interval. Pyrite nodules occur sporadically throughout. The cores are strongly affected by biscuiting drilling disturbance. Physical properties, paleomagnetics, and geochemistry measurements are ongoing.

Daily Science Report for 13 March 2014

LOCATION: Hole U1433B (12°55.1313′N, 115° 2.8484′E; water depth 4379 m)

SCIENCE UPDATE: We cut and recovered Cores U1433B-25R to ‑43R (407.5–591.8 mbsf), with an average recovery of 73%. These cores are late Miocene to Pliocene in age based on calcareous nannofossil and planktonic foraminifer biostratigraphy. Cores below U1433B-36R are either barren of foraminifers or contain only rare occurrences of taxa that are not biostratigraphically significant.

Cores U1433B-10R through ‑19R were split and described. These cores consist of dark greenish gray clay intercalated with light greenish gray nannofossil ooze and nannofossil-rich clay. Bioturbation is heavy throughout. Most cores are strongly affected by biscuiting drilling disturbance.

Daily Science Report for 12 March 2014

LOCATION: Hole U1433B (12°55.1313′N, 115°2.8484′E; water depth 4379 m)

SCIENCE UPDATE: Cores U1433B-4R through ‑24R (203.8–407.5 mbsf) were collected, averaging 68% recovery. The age over this interval is late Pliocene to Middle Pleistocene based on calcareous nannofossil and planktonic foraminifer biostratigraphy.

Cores U1433A-18H through ‑20H were split and described. These cores consist of dark greenish gray and light greenish gray clay, with occasional dark reddish clay intervals. The light green gray clay contains more carbonate (primarily calcareous nannofossils) than the other intervals. Bioturbation is moderate to heavy throughout. Very rare, very thin bedded silt layers are interpreted as turbidites.

Cores U1433B-2R through ‑9R were also split and described. The sediment over this interval also consists alternating layers of dark greenish gray, light greenish gray, and dark reddish gray clay. Nannofossil ooze is present near the bottom of the interval. Rare clay with silt intervals are interpreted as turbidites.

Daily Science Report for 11 March 2014

LOCATION: Hole U1433B (12°55.1313′N, 115°2.8484′E; water depth 4379 m)

SCIENCE UPDATE: We finished pulling out of the hole, made up the RCB coring assembly, and then tripped back to the seafloor. Hole U1433B was spudded at 1515 h and drilled down to 186.1 mbsf. Cores U1433A-2R and ‑3R were collected, both with low recovery (22% and 32%, respectively). The sediment is Middle Pleistocene in age (<0.9 Ma) based on calcareous nannofossil and planktonic foraminifer biostratigraphy.

Cores U1433A-10H through ‑17H were split and described. This interval consists mostly of clay and thin interbeds of clay with silt. The clay is color banded and varies from dark greenish gray to dark gray or dark reddish gray. Lighter-colored intervals have higher nannofossil content. Thin silty turbidites occur sporadically, as do occasional volcanic ash layers. Paleomagnetics results over this interval indicate that the sediment was deposited within the Brunhes Chron (<0.78 Ma), which is consistent with biostratigraphic results.

Daily Science Report for 10 March 2014

LOCATION: Site U1433 (12°55.1380′N, 115°2.8345′E; water depth 4379 m)

SCIENCE UPDATE: We continued APC coring, recovering Cores U1433A-12H to ‑20H (103.9–188.3 mbsf). After several partial strokes of the APC core barrel, we decided to terminate the hole and began pulling out of the hole. Core recovery was excellent (99%) over the cored interval. The age at the base of the hole is between 0.6 and 0.9 Ma based on calcareous nannofossil biostratigraphy.

Our next step will be to deploy the RCB coring system, spud Hole U1433B, drill down to just above the refusal depth of Hole U1433A (188.3 mbsf), and then RCB core the remaining sediment section and at least 100 m into basement.

Cores U1433A-3H through ‑9H were split and described. The sediment is primarily composed of dark greenish gray clay, with some intervals of reddish gray clay, nannofossil-rich clay, and nannofossil ooze. A few silt and silty clay layers have sharp bases and grade upward. We interpret these as turbidites. Geochemistry, paleomagnetic, and physical properties measurements are ongoing.

Daily Science Report for 9 March 2014

Location: Site U1433 (12°55.1380′N, 115°2.8345′E [final]; water depth 4379 m)

SCIENCE UPDATE: We spudded Hole U1433A at 1000 h, collecting Cores U1433A-1H to ‑11H (0–103.9 mbsf). Core U1433A-5H came back essentially empty (<0.1% recovery) and Core U1433A-9H had only 44% recovery. Otherwise, recovery has generally been good, ranging from 77% to 105%, with an average recovery of 81% over the cored interval. The sediment is late Middle to Late Pleistocene in age (<0.40 Ma) based on calcareous nannofossil and planktonic foraminifer biostratigraphy.

Cores U1433A-1H to ‑2H were split and described. The cores consist of dark greenish gray and dark grayish brown clay and clay with silt. Core U1433A-1H includes interbeds of reddish gray clayey silt. A lighter colored interval of nannofossil ooze with clay is present in Core U1433A-2H. Bioturbation is moderate to heavy. Temperature measurements with the APCT-3 tool on Cores U1433A-4H, ‑7H, and ‑10H indicate a high temperature gradient of ~78°C/km for the site.

Daily Science Report for 8 March 2014

LOCATION: Site U1433 (12°55.1370′N, 115°2.8326′E [preliminary]; water depth 4379 m)

SCIENCE UPDATE: We arrived at Site U1433 at 0230 h and switched to dynamic positioning control. We made up the APC/XCB bottom-hole assembly and began tripping down to the seafloor. After picking up and adding the 24th stand of drill pipe to the drill string, a tool joint in this stand failed at 0520 h. After removing this stand and the one directly below, we continued tripping pipe. Shortly thereafter, another tool joint parted while picking up the stand from the pipe racker. We decided to remove all 5 inch pipe from the drill string that had been involved in the operations at Hole U1432B. We then began tripping back toward the seafloor, with additional pipe picked up from the riser hold.

We discussed shipboard sampling for Site U1433 in greater detail at the crossover meeting. We also discussed coordinating a plan for higher resolution sampling during the moratorium period, since we were unable to take all requested samples during the expedition. Scientists also began preparing for the arrival of new core on deck.

Daily Science Report for 7 March 2014

LOCATION: In transit to Site U1433 (proposed site SCS-4B)

SCIENCE UPDATE: The co-chiefs presented the science objectives for Site U1433, which include determining the termination age of seafloor spreading in the Southwest Sub-Basin of the South China Sea and elucidating the cause of the distinct magnetic contrasts between the East and Southwest Sub-basins. We also discussed the shipboard sampling plan for the site. Scientists also finalized first drafts of the Site U1432 reports.

Daily Science Report for 6 March 2014

LOCATION: In transit to Site U1433 (proposed site SCS-4B)

SCIENCE UPDATE: We attempted to sever the drill pipe at 0430 h, but could not free the drill string despite applying overpull up to 100 klb. So, we installed the top drive and used rotation combined with overpull to free the pipe. After the pipe was recovered, we secured the vessel for transit and departed for Site U1433 (proposed Site SCS-4B) at 2036 h.

Scientists began finalizing their Site U1432 reports. We also held a science meeting to discuss our operations plan for the remainder of the expedition. Although we had intended to go first to alternate Site SCS-6C, 18 nmi from Site U1432, we re-evaluated this decision due to deteriorating weather conditions and increased heave (~2.5 m), which would make a hard rock spud-in with little sediment cover difficult. Instead, we decided to move to primary Site SCS-4B, with the intention of leaving enough time at the end of the expedition to return to alternate Site SCS-6C.

Daily Science Report for 5 March 2014

LOCATION: Hole U1432B (18°21.1062′N, 116°23.4512′E; water depth 3829 m)

SCIENCE UPDATE: We reentered Hole U1432B, and then ran in to 767.5 mbsf to prepare for cementing operations. After pumping seawater at 60 strokes per minute to verify circulation, we pumped 14 barrels of 15.5 ppg cement, and then displaced the cement with 263 barrels of seawater. We began to pull out of the hole to 748.8 mbsf, with overpull increasing significantly from 20 klbs to 100 klbs. When we tried to continue pulling out of the hole after removing a double of drill pipe, we were unable to move the pipe up or down. We continued to work the pipe and attempted rotation for most of the day; however, when no progress was made we began to rig up for severing operations.

We continued with science presentations by members of the science party during our midday crossover meeting. Yi-Ching Yeh discussed Eocene seafloor spreading and volcanic activities in the northwestern corner of the West Philippine Basin. Tao Jiang presented his work from IODP Expedition 316 to the Nankai Trough off Japan, which included optically stimulated luminescence and zircon dating of sandy intervals, and how he will apply these techniques to sediments from the South China Sea. Zhifei Liu discussed his work using clay mineral assemblages to track sediment sources in the South China Sea, particularly using sediment collected in sediment traps along the northern margin. Finally, Xixi Zhao discussed new magnetostratigraphic results from Ocean Drilling Program Site 1148, located ~60 km north of Site U1432.

Daily Science Report for 4 March 2014

LOCATION: Hole U1432B (18°21.1062′N, 116°23.4512′E; water depth 3829 m)

SCIENCE UPDATE: We finished pulling out of the hole and prepared to run back in for cementing. At the end of the day we were tripping pipe back down toward the seafloor.

The science party continued working on revisions of the Site U1431 site reports. Four of the scientists also presented some of their research at our crossover meeting. Anthony Koppers showed results from IODP Expedition 330 to the Louisville Seamount Chain, which indicate that the Louisville mantle plume has migrated about 2.5° of latitude through time. Chuanlun Zhang spoke about the role of archaea in the deep biosphere. Zhen Sun presented her work about the breakup pattern of the South China Sea. Finally, Qianyu Li showed paleontologic results that map the occurrence of Paleocene and Eocene deposits in the northeastern South China Sea.

Daily Science Report for 3 March 2014

LOCATION: Hole U1432B (18°21.1062′N, 116°23.4512′E; water depth 3829 m)

SCIENCE UPDATE: We reentered Hole U1432B and successfully landed and released the 10.75 inch casing at 1745 h. We then began to pull out of the hole to rig up for cementing operations.

A revised draft of the Site U1431 Summary was distributed to the science party for final review. We also made several lab group Methods sections available for review by the science party prior to submission of the final version. Additional Methods sections, as well as Site U1431 reports, will be printed for this review as they become available. We also held a science meeting with presentations by several scientists. Elizabeth Brown presented her work on geochemical variations among different foraminifer morphotypes and implications for paleoceanographic reconstructions. Alyssa Peleo-Alampay spoke about calcareous nannoplankton assemblages from sediment traps in the South China Sea. Fan Zhang presented variations in oceanic plate bending along the Mariana and Philippines trenches.

Daily Science Report for 2 March 2014

LOCATION: Hole U1432B (18°21.1062′N, 116°23.4512′E; water depth 3829 m)

SCIENCE UPDATE: We completed making up the 10.75 inch casing to 737.8 mbrf and landed it on the moonpool doors. We latched into the casing at 1655 h and began lowering it through the water column, filling the pipe with seawater every 20 stands. At the end of the day we were nearing the seafloor and preparing to deploy the subsea camera for reentry.

The science party continued revising the Site U1431 reports and writing up results from Hole U1432C. We discussed shipboard sampling for the remainder of Hole U1432B. The Staff Scientist presented a graphic depiction designed to illustrate the different reports each lab group is responsible for and where those reports go. This led to a general discussion about the expedition Preliminary Report and Proceedings volume. Igneous petrologist Guo-Liang Zhang presented his work on basalts cored during Integrated Ocean Drilling Program Expedition 329 (South Pacific Gyre Subseafloor Life).

Daily Science Report for 1 March 2014

LOCATION: Hole U1432B (18°21.1062′N, 116°23.4512′E; water depth 3829 m)

SCIENCE UPDATE: After tripping out of the hole, we made up and tested the casing stinger components, which include an underreamer with the arm diameter set to 12.75 inches and a mud motor. We then began to make up and run the 10.75 inch casing.

We held a science meeting to discuss the results from Hole U1432C, which has provided valuable information that we did not anticipate getting based on our original operations plan. Specifically, the depth of the sulfate-methane transition and the temperature gradient at the site are particularly important.