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September >
IODP Expedition 352
Izu-Bonin-Mariana Forearc
Daily Science Report for 31 August 2014
LOCATION: Hole U1439C (28°24.4491′N, 142°36.5368′E, 3129 m water depth; proposed Site BON-2A)
SCIENCE UPDATE: Cores U1439C-17R to 20R penetrated from 309.3 to 348.3 mbsf and recovered 12.2 m (31%). Following the recovery of Core 20R, the drill string was raised to the surface to change the bit. By the end of the day, the drill string had been lowered back down to 761 m below rig floor.
Cores U1439C-14R to 18R are dominated by boninite pillow lava, typically fractured and veined, with orthopyroxene ± olivine or clinopyroxene phenocrysts. Curved chilled margins on several of the larger pieces indicate that these are pillow lava flows with some interpillow breccia. This lava sequence has a distinct purple-gray color. Rocks from 243 to 250 mbsf are augite-plagioclase phyric and contain modal plagioclase in the groundmass. Cores 14R-17R contain 56 macroscopic structures that consist mostly of calcite-zeolite tension veins with relatively steep attitudes. Some of these veins occur between pillows or along pillow margins.
Daily Science Report for 30 August 2014
LOCATION: Hole U1439C (28°24.45′N, 142°36.54′E, 3129 m water depth; proposed Site BON-2A)
SCIENCE UPDATE: Cores U1439C-12R to 16R penetrated from 270.4 to 303.6 mbsf and recovered 10.3 m (26%). A wiper trip was conducted between 1130 and 1315 h, and 3 m of fill was removed from the bottom of the hole. Hole conditions continued to be good.
Cores U1439C-9R to 13R are dominated by boninite lava, typically fractured and veined, with orthopyroxene ± olivine or clinopyroxene phenocrysts. Curved chilled margins on several of the larger pieces indicate that these are pillow lava flows, with some interpillow breccia. Fractures and veining are common in some sections, with most veins filled by calcite. Pipe vesicle trains in Sections U1439C-8R-2 and 9R-1 are inclined from vertical, indicating that the formation has been tilted by ~50°. Alternatively, this could be a younger, cross-cutting dike.
A meeting was held to discuss the logging results for Hole U1440B.
Daily Science Report for 29 August 2014
LOCATION: Hole U1439C (28°24.45′N, 142°36.54′E, 3129 m water depth; proposed Site BON-2A)
SCIENCE UPDATE: Cores U1439C-4R to 11R penetrated from 201.6 to 270.4 mbsf and recovered 13.9 m (20%).
Cores U1439C-2R to 8R are dominated by a heterolithic breccia consisting of olivine-phyric boninite lavas, black olivine-phyric boninite glass, and black olivine-phyric boninite scoria. The breccia matrix consists of small lithic granules from these lithologies, as well as olivine crystals and dark green “mud” that is most likely altered glass shards.
Cores 4R–6R are dominantly boninite lava, typically fractured and veined, with olivine ± orthopyroxene phenocrysts. These may represent a pillow lava flow within the breccia, and some interpillow sediment. This is underlain by more heterolithic breccia with lava interbeds in Cores 7R–8R.
A meeting was held to discuss the scientific results for the igneous basement recovered at Site U1440.
Daily Science Report for 28 August 2014
LOCATION: Hole U1439C (28°24.45′N, 142°36.54′E, 3129 m water depth; proposed Site BON-2A)
SCIENCE UPDATE: The bottom-hole assembly (BHA) used to drill in the casing at Hole U1439C was back on the rig floor by 0415 h. An RCB BHA was made up and the drill string reached the seafloor at 1230 h. The subsea camera was sent to the seafloor at 1245 h, the ship started maneuvering for reentry at 1410 h, and Hole U1439C was reentered at 1415 h. The camera was brought back to the surface, and coring resumed at 1700 h, from slightly below the end of the casing. Cores U1439C-2R to 3R penetrated from 182.0 to 201.6 mbsf and recovered 7.6 m (39%).
Approximately 700 samples were collected for postcruise research from the basement units at Site U1440.
Daily Science Report for 27 August 2014
LOCATION: Hole U1439C (28°24.45′N, 142°36.54′E, 3128 m water depth; proposed Site BON-2A)
SCIENCE UPDATE: The day started with the reentry system for Hole U1439C being lowered through the moonpool at 0000 h and down to the seafloor. The reentry system reached the seafloor at 0600 h and the subsea camera was deployed to monitor the reentry cone system while drilling it into the seafloor. Hole U1439C was spudded at 0745 h and it took 10.75 h to drill in the end of the casing string to 178.5 mbsf. The casing running tool was unlatched from the reentry cone at 1830 h, and the rest of the day was spent recovering the drill string and bottom-hole assembly.
The science party continued refining their sample selections for postcruise research from the basement recovered from Holes U1440A and U1440B.
A meeting was held to discuss the scientific results for the sedimentary section recovered in Hole U1440A.
Daily Science Report for 26 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A);
Hole U1439C (28°24.45′N, 142°36.54′E, 3128 m water depth; proposed Site BON-2A)
SCIENCE UPDATE: The logging pass with the FMS-sonic tool string ended at 0200 h and the tools had been brought to the surface and rigged down by 0330 h. We started raising the drill string, recovered the beacon at 0612 h, and started the slow transit to Site U1439 at 0624 h while continuing to pull the drill string to the surface. The end of the drill string reached the rig floor at 1210 h and the 8.2 nmi transit was completed at 1430 h. Preparations began for installing the reentry system at Hole U1439C. First, the reentry cone was moved to the moonpool doors at 1400 h, and a 16 inch casing hanger was latched in it. Second, a 178 m long casing string was assembled that comprises a 10.75 inch casing hanger and 13 joints of 10.75 inch casing welded together to reinforce the connections. A casing running tool was used to latch the casing string into the reentry cone at 2000 h. Third, a drilling bottom-hole assembly (BHA) was made up that comprises a bit, underreamer, and mud motor. The underreamer and mud motor were tested and the casing running tool was used to latch the BHA into the reentry cone at 2400 h.
The last geochemical and paleomagnetic measurements were completed for Hole U1440B.
Scientists revised their research plans and started the process of selecting samples for postcruise research from the basement units in Holes U1440A and U1440B.
Daily Science Report for 25 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: The subsea camera reached the surface following a 3 h repair to the draw works load cell. The drill string was lowered to ~96 mbsf, just inside the end of the casing. The triple combo tool string was rigged up with the Ultrasonic Borehole Imager at the bottom and run into the hole at 0630 h. By 1645 h, two passes had been logged down to 254 mbsf, where the tool string encountered an obstruction. Next, the FMS-sonic tool string was rigged up and run into the hole at 1830 h. At midnight, logging data were being collected with the FMS-sonic tool string from 243 mbsf, where another obstruction was encountered. Approximately 125 m of the basement was logged and the data collected appear to be of good quality. Once logging is completed we will return to Site U1439.
The petrology and geochemistry team continued to refine the igneous rock units in preparation for personal sampling of Hole U1440A and U1440B igneous rocks.
Thermal demagnetization measurements continued on discrete samples from the last few cores.
Preparations continued for taking Site U1440 samples for individual postcruise research projects.
Daily Science Report for 24 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: The early part of the day was spent retrieving the drill string in preparation for logging. The RCB drill bit arrived on the rig floor at 0945 h, and it was immediately evident it had sustained heavy damage as all four of its roller cones were gone. A logging bottom-hole assembly was made up and the drill string was lowered to just above the seafloor. The subsea camera was sent to the seafloor at 1800 h, Hole U1440B was reentered at 2125 h, and the camera was retrieved.
The petrology team continued to refine the igneous rock units in preparation for personal sampling of Hole U1440A and U1440B igneous rocks.
The last portable XRF “chemostratigraphic” analyses were conducted on archive-half pieces from Hole U1440B cores as well as thin section billets and powders from Hole U1439A. So far, ~1108 individual pXRF measurements have been conducted on Hole U1439A and U1440B materials. ICP measurements continued on Hole U1440B samples.
Core 35R shows a distinct one-inch-wide cataclastic zone characterized by narrowly-spaced thin veins of chlorite. In Core 33R, even samples that looked relatively unaltered are actually pervasively altered with chlorite locally forming aligned clots. Preferred alignment of magmatic crystals remains relatively rare and restricted to small domains.
Moisture and density measurements were completed through Core 35R.
Thermal demagnetization measurements continued on discrete samples from the last few cores.
The science party met to discuss the procedures we will follow for taking Site U1440 samples for individual postcruise research projects.
A reentry cone has been constructed for the reentry system at Site U1439, and the weather continues to be excellent for the upcoming logging and casing operations.
Daily Science Report for 23 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: After spending most of the night trying to core and encountering high torque, the decision was made to pull Core U1440B-37R (377.6–382.6 mbsf) to see what was happening. Core 37R arrived on the rig floor at 0930 h with an empty core barrel, suggesting something may be clogging the drill bit. A core barrel with a deplugger at the end was sent down to clear the jammed bit. When it was brought back to the surface, it got stuck in the blocks above the rig floor. An inspection revealed slight damage to the wireline BOP and several hours were spent removing the sinker bar and core barrel and replacing the damaged part. We resumed RCB coring but after taking 5 h to penetrate just 1 m, Core 38R (382.6–383.6 mbsf) was pulled and also came up empty. Damage to the core catcher sub indicated that the bit had probably failed and left pieces of metal at the bottom of the hole. Given this information and the rock types recovered so far, we decided to stop coring in Hole U1440B. The last part of the day was spent retrieving the drill string in preparation for wireline logging.
Moisture and density measurements were completed through Core 26R. P-wave caliper and thermal conductivity measurements were completed through Core 34R.
Shipboard thin section, ICP, XRD, XRF, and MAD/PMAG samples were selected during the midday sampling party.
Portable XRF “chemostratigraphic” measurements continued on archive-half pieces, thin section billets, and powders.
The petrology team worked on refining the igneous rock units based on hand-specimen/petrographic descriptions and XRF analyses.
Several pieces from Cores 35R–36R seem to display magmatic foliation. Microstructures in thin sections reveal a general lack of shape-preferred orientation except local flow. Grain size drastically increases below Core 33R.
Remanent magnetization measurements continued on discrete samples from the last few cores.
A meeting was held to discuss the configuration of the logging tool strings.
Daily Science Report for 22 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Cores U1440B-34R to 36R penetrated from 348.4 to 377.6 mbsf and recovered 3.4 m (12%). Once we were done cutting Core 36R, we experienced very high torque and lost the ability to circulate. The drill string had to be raised to 218 mbsf before conditions improved, and Core 36R was retrieved on deck at 1900 h. Another core barrel was dropped to verify that circulation had been restored. The drill string was lowered back down to 235 mbsf, when an obstruction was encountered, and the last part of the day was spent cleaning the hole of debris from 235 to 355 mbsf.
Whole-round bulk density, magnetic susceptibility, and natural gamma ray measurements were completed through Core 36R. Moisture and density, P-wave caliper, and thermal conductivity measurements were completed through Cores 22R, 26R, and 28R, respectively.
Cores 33R–36R were split, imaged, and measured for magnetic susceptibility and color reflectance. Some cores had whole-round images taken prior to splitting. Shipboard thin section, ICP, XRD, XRF, and MAD/PMAG samples were selected during the midday sampling party. Four thin sections were described.
Igneous rocks in Cores 33R to 36R are fine- to medium-grained mafic rocks with doleritic to seriate textures. No chilled margins were confirmed, but these rocks appear to represent hypabyssal intrusive sheets best described as dolerite or microgabbro. A presentation was made to the science party about using the results from the portable XRF to define basalt units and develop a chemical stratigraphy.
Portable XRF “chemostragraphic” measurements were made on archive-half pieces, thin section billets, and powders. ICP analyses were conducted on 14 samples from Hole U1440B.
Cores 32R–36R contained 24 subvertical to steeply inclined veins. Veins are mainly filled with (Mg–) calcite and chlorite that precipitated from hydrothermal fluids. Viscous flow fabrics related to magmatic flow are rarely observed.
Remanent magnetization measurements were completed for archive-half pieces through Core 36R and discrete samples through Core 26R. Measurements indicate a predominantly normal polarity basement with a reversed polarity zone at ~175–225 mbsf.
Daily Science Report for 21 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Cores U1440B-30R to 33R penetrated from 309.5 to 348.4 mbsf and recovered 3.9 m (10%). After recovering Core 32R (1345 h; 338.7 mbsf), we spent 4.25 h conducting a wiper trip, the last 1.5 h of which was spent washing and reaming the hole from 232 mbsf to the bottom of the hole. We resumed RCB coring at 1800 h and Core 33R arrived on deck just before midnight.
Whole-round bulk density, magnetic susceptibility, and natural gamma ray measurements were completed through Core 32R. Moisture and density, P-wave caliper, and thermal conductivity measurements continued.
Cores 29R–32R were split, imaged, and measured for magnetic susceptibility and color reflectance. Some cores had whole-round images taken prior to splitting. Shipboard thin section, ICP, XRF, and MAD/PMAG samples were selected during the midday sampling party. Four thin sections were described.
Igneous rocks in Cores 29R to 32R are dominantly aphyric to sparsely phyric basalts with a microcrystalline groundmass of plagioclase, pyroxene, and oxides. Glass forms selvages on some of the larger fragments and small glass-rich fragments are common. Some samples appear to be coarser grained (dolerites).
Portable XRF “chemostragraphic” measurements were made on archive-half pieces. Reference materials and samples from Hole U1440B were prepared for CHNS analyses.
Fourteen structures were recorded in Cores 29R–32R. These include magmatic flow structures marked by alignment of mafic minerals. Veins of chlorite become wider and more abundant, confirming the gradual increase in metamorphic conditions.
Remanent magnetization measurements continued, including thermal demagnetization of discrete samples.
Daily Science Report for 20 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Cores U1440B-25R to 29R penetrated from 260.8 to 309.5 mbsf and recovered 3.8 m (8%). We have resumed coring with a full advancement of 9.8 m per core to get deeper faster.
Whole-round bulk density, magnetic susceptibility, and natural gamma ray measurements were completed through Core 29R. Moisture and density and P-wave caliper measurements were completed through Core 22R.
Cores 23R–28R were split, imaged, and measured for magnetic susceptibility and color reflectance. Some cores had whole-round images taken prior to splitting. Shipboard thin section, ICP, XRD, XRF, and MAD/PMAG samples were selected during the midday sampling party. Three thin sections were described.
Igneous rocks in Cores 23R to 28R are dominantly aphyric to sparsely phyric basalts with a groundmass of plagioclase, pyroxene, and oxides. Some samples appear to be coarser grained and may contain an igneous fabric.
Portable XRF “chemostragraphic” analyses were conducted on archive-half pieces from Cores 24R to 27R. A chemostratigraphic data protocol was developed to facilitate correlation of these data with other data sets.
Fractures and veins decrease below Core 22R. Examination of microstructures in thin sections shows that most volcanic rocks are free of primary flow structures. Most veins indicate a multiple-step opening process.
Remanent magnetization measurements continued, including thermal demagnetization of discrete samples.
Daily Science Report for 19 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: The entire day was spent lowering the drill string to the previous coring depth. The drill string was lowered to 4774 m by 0745 h, and the subsea camera reached the seafloor at 1200 h, following a 1 h delay to repair the camera winch. The ship started maneuvering for reentry and Hole U1440B was reentered at 1300 h. After the camera was recovered (1615 h), we lowered the bit into the hole until an obstruction was encountered at 163 mbsf. We installed the top drive, washed/reamed back down to the bottom of the hole, and resumed coring at 1900 h. Core U1440B-24R was cored from 251.1 to 260.8 mbsf with 0.6 m recovered (6% recovery).
Thermal conductivity measurements were completed through Core 19R. Moisture and density and P-wave caliper measurements were completed through Core 15R.
Shipboard thin section, ICP, XRD, XRF, and MAD/PMAG samples were selected during the midday sampling party.
The petrology team reviewed Cores 4R through 23R for their petrology and petrography, assessed the macroscopic volcanic stratigraphy, and cross-checked their descriptions in DESClogik for consistency. Uncalibrated output from the portable XRF unit was integrated with the petrologic (macroscopic) and petrographic (thin section) data to define preliminary stratigraphic units. At least six broad igneous units are recognized. The portable XRF is extremely useful for rapid monitoring of large numbers of samples, especially when those samples vary little in their visually-observed phenocryst assemblages and abundances.
Major and trace analyses were completed on a third batch of sediment and rock samples from Holes U1440A and U1440B. Portable XRF “chemostragraphic” analyses were conducted on archive-half pieces of a large number cores.
Material encountered in veins commonly includes calcite (or magnesian calcite), quartz (or tridymite), chlorite, hematite, and altered glass clasts. Most thin-sections of basaltic rocks or basaltic glass exhibit only magmatic, equilibrated microstructures characterized by polygonal grain boundaries. Grains do not exhibit specific alignment resulting from viscous flow. Fiamme structures in volcanic glass, however, attest of magma flow direction. Vesicules, when present, are quasi-spherical, and do not display any particular elongation. Devitrified areas are characterized by spherulitic microstructures without spherulites being aligned.
Remanent magnetization measurements continued, including thermal demagnetization of discrete samples.
Daily Science Report for 18 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Cores U1440B-21R to 23R were cored from 236.4 to 251.1 mbsf with 2.2 m recovered (15%). Following the recovery of Core 23R, the entire 5 km drill string was raised to the surface to replace the RCB bit, which had reached its maximum operating hours. After the bit was back on the rig floor (2100 h), we installed a new bit, and started lowering it back down to the seafloor. The bit had reached 761 m below rig floor by the end of the day.
Whole-round bulk density, magnetic susceptibility, and natural gamma ray measurements were completed through Core U1440B-23R. Thermal conductivity, moisture and density, and P-wave measurements continued on discrete samples.
Cores 21R–23R were split, imaged, and measured for magnetic susceptibility and color reflectance. Some cores had whole-round images taken prior to splitting. Shipboard thin section, ICP, XRD, XRF, and MAD/PMAG samples were selected during the midday sampling party. Eight thin sections were described.
Igneous rocks in Cores 21R to 23R are dominantly aphyric to sparsely phyric basalts with a groundmass of plagioclase, pyroxene, and oxides. Thin veins of quartz or calcite are present on fractures. These basalts exhibit some alteration, but otherwise are remarkably fresh. Basalt units were reviewed and a preliminary stratigraphy developed.
Fifty-eight discrete structures were identified in Cores 18R–23R, including tension fractures, calcite veins, brecciated veins, and vein networks. The overall number and width of veins increases with depth.
Remanent magnetization measurements continued for archive-half pieces and working-half samples from Cores 21R–22R.
The XRF station was moved from the Chemistry Laboratory into the Paleo Prep Laboratory to facilitate core flow. Small pieces from Cores 4R to 14R were measured using the portable XRF to help define a chemical stratigraphy.
Daily Science Report for 17 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Cores U1440B-16R to 20R were cored from 202.5 to 236.4 m below seafloor (mbsf) with 4.3 m recovered (13%). After Core 17R, a wiper trip was conducted from 1000 to 1245 h to improve hole conditions. We switched to half cores and no liners with Core 18R to improve recovery.
Whole-round bulk density, magnetic susceptibility, and natural gamma ray measurements were completed through Core U1440B-19R. Thermal conductivity measurements were completed on discrete samples from Cores 10R–11R. Moisture and density and P-wave measurements were completed on discrete samples from Cores 12R–16R.
Cores 15R–20R were split, imaged, and measured for magnetic susceptibility and color reflectance. Some cores had whole-round images taken prior to splitting. Shipboard thin section, ICP, XRD, XRF, and MAD/PMAG samples were selected during the midday sampling party. Six thin sections were described.
Igneous rocks in Cores 15R–20R are dominantly aphyric to sparsely phyric basalts with a groundmass of plagioclase, pyroxene, and oxides. These basalts exhibit some oxidative alteration, but otherwise are remarkably fresh. Core 19R contains large fragments of black basaltic glass, aphyric and lacking vesicles. The glass is largely devitrified but some fresh glass remains. Cores 17R and 18R contain abundant hydrothermal veins containing quartz, calcite, epidote, and other secondary minerals.
Thirty-six discrete structures were identified in Cores 14R–17R, including tension fractures, calcite veins, brecciated veins, and vein networks. Vein distribution with depth seems rather variable from unit to unit but overall the number and width of veins seems to increase with depth.
Remanent magnetization measurements were completed for archive-half discrete pieces from Cores 12R–20R. Whereas pieces above Core 12R contain a stable magnetization, those below do not. This occurs at the same level as a brown-colored alteration, implying that the alteration has altered the magnetic grains in a way that makes them poor magnetic field recorders.
A batch of 20 samples from Holes U1439A and U1440A is being measured for their major and trace element concentrations via ICP-AES.
Daily Science Report for 16 August 2014
LOCATION: Hole U1440B (28°26.9976'N, 142°45.2244'E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Cores U1440B-12R to 15R were cored from 163.6 to 202.5 m below seafloor (mbsf) with 4.3 m recovered (11%). As it became increasingly difficult to get to the bottom of the hole due to material falling in from the top, a wiper trip was conducted from 1145 to 1500 h to improve hole conditions.
Whole-round bulk density, magnetic susceptibility, and natural gamma ray measurements were completed through Core U1440B-14R. Thermal conductivity measurements were completed on discrete samples from Cores 7R–8R. Moisture and density and P-wave measurements were completed on discrete samples from Cores 4R and 6R.
Cores 11R–14R were split, imaged on the Section Half Imaging Logger (SHIL), and measured for magnetic susceptibility and color reflectance. Some cores had whole-round images taken prior to splitting. Shipboard thin section, ICP, and XRF samples were selected during the midday sampling party.
The igneous rocks in Cores 5R–14R consist of aphyric to sparsely phyric basalts with a groundmass of plagioclase, pyroxene, and oxides. Unit boundaries are difficult to define. Core 12R recovered basalt cut by a network of hydrothermal veins comprising quartz, calcite, and other phases.
Cores 10R–12R contained 26 structures. The dominant structures are thin fractures with small alteration halos from 144.8 to 164.2 mbsf, and subvertical to inclined calcite veins from 164.2 to 165.9 mbsf.
Remanent magnetization measurements were completed through Core 14R for core section halves and through Core 11R for discrete samples.
Tests of the portable XRF instrument were expanded to develop calibration curves for key major and trace elements using dunites, boninites, basalts, and andesites as reference materials.
Daily Science Report for 15 August 2014
LOCATION: Hole U1440B (28°26.9976′N, 142°45.2244′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Cores U1440B-8R and 10R–11R were cored from 136.4 to 163.6 m mbsf with 3.3 m recovered (12%). After Core 8R, we had to repair of a leaking connection in the drill string and Core 9G (102.3–144.1 mbsf) recovered 5.7 m of material while drilling back to the bottom of the hole. Slow penetration rates and erratic torque conditions continued.
Whole-round magnetic susceptibility and natural gamma ray measurements were completed through Core U1440B-10R. Thermal conductivity measurements of igneous rock pieces are in progress.
Cores 4R–10R were split, imaged, and measured for magnetic susceptibility and color reflectance. Some pieces from Core 8R had whole-round images taken prior to splitting. Shipboard thin section, ICP, and XRF samples were selected for Cores 4R–7R.
A manganese-rich layer in Core 4R marks the sediment-igneous basement contact. The basement consists of a few decimeters of igneous talus overlying an aphyric, very fine grained to microcrystalline basalt that has experienced seafloor weathering. Underlying basalts vary only slightly in texture and phenocryst content. It is not possible to tell if these basalts represent pillow lavas or sheet flows.
Cores 4R–8R contain subvertical extensional fractures accompanied by millimeter-thick alteration seams. Magmatic flow structures, defined by the alignment of platy or elongate minerals, are observed in Core 8R.
Remanent magnetization measurements have been completed through Core 8R for core section halves, and through Core 3R for discrete samples.
Carbonate-rich sediment samples and standards were prepared for ICP-AES and CHNS analyses. Quality control of previous ICP-AES measurements was performed.
Although Core 9G is composed of a mixture of materials that cannot be placed in their proper depth in the borehole, it contains material suitable for some analyses, such as fresh glass that could represent pillow rims or hyaloclastite.
Daily Science Report for 14 August 2014
LOCATION: Hole U1440B (28°26.99′N, 142°45.22′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Once the underwater camera reached the seafloor, the ship maneuvered to locate the reentry cone and Hole U1440B was quickly reentered at 0021 h. The camera was brought back to the surface and the drill string was lowered to 102.3 mbsf and RCB coring started at 0400 h. RCB Cores U1440B-2R to 7R advanced from 102.3 and 136.4 m below seafloor (mbsf). There was a drop in recovery at the sediment/basement interface, which was encountered at 124.7 mbsf near the top of Core 4R. Overall, we recovered 8.9 m of core from the 34.1 m cored (26%). We are coring through relatively fresh, crystalline basalt and are experiencing slow penetration rates as a result.
Whole-round magnetic susceptibility, P-wave velocity, natural gamma ray, and thermal conductivity measurements were completed for Cores U1440B-2R to 6R.
Cores 2R–3R were split, imaged on the Section Half Image Logger (SHIL), measured for magnetic susceptibility and color reflectance, and sampled for shipboard and personal samples. Moisture and density measurements were made on Cores 2R and 3R.
ICP-AES data are being evaluated for the Hole U1439A samples.
The science party concluded the Hole U1439A science meetings.
Daily Science Report for 13 August 2014
LOCATION: Hole U1440B (28°26.99′N, 142°45.22′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: We continued to raise the drill string to the surface. The end of the drill string reached the rig floor at 0700 h and the underreamer and mud motor were flushed with water to remove debris. The rig floor crew assembled the rotary core barrel (RCB) bottom-hole assembly followed by stands of drill pipe, and by 2100 h the drill string had reached 4774 m below rig floor. In preparation for reentering Hole U1440B, the underwater camera was sent to the seafloor, which lasted from 2100 to 2400 h.
Twenty samples from Hole U1439A were prepared for ICP-AES analysis and measured.
Lab teams continued to work on their Hole U1439A reports and science meeting presentations.
The Operations Superintendent completed four ship tours for the science party.
Daily Science Report for 12 August 2014
LOCATION: Hole U1440B (28°26.99′N, 142°45.22′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Casing operations continued throughout the day. First, the reentry system (reentry cone and casing string) was lowered to 4753 m below rig floor. At 0745 h, the underwater camera was sent down so that we could observe the reentry cone during the next phase. At 1100 h we started advancing the 10.75 inch casing string into the sediment by drilling ahead of it using an underreamer and a mud motor to rotate it. It took ~4.5 h for the ~100 m of casing to be drilled into the formation, and at 1535 h the reentry cone settled on the seafloor (4775 m). The camera was brought to the surface at 1900 h, followed by the drill string with the underreamer at the end. At the end of the day the drill string was at 1929 m below rig floor. This marks the first time a reentry system was installed in this way. We estimate that 5 d of operations time was saved compared to the more traditional way of installing reentry systems, which could prove extremely beneficial over the course of the expedition.
Remanent magnetization measurements have been completed for 72 sections and 54 discrete samples from Hole U1440A. Directions are affected by a strong drilling-induced overprint.
A batch of 25 sediment samples were analyzed for inorganic CO2, total carbon, and total nitrogen (CHNS, coulometry). X-ray fluorescence spectrometry tests were conducted to determine the reproducibility and accuracy of the Niton P-XRF instrument and to assess its viability for use on fresh rock samples as well as powders. These tests were successful, and further use of the XRF system is planned.
Lab teams worked on their Hole U1439A reports and on presentations for science meetings scheduled for 13–14 August.
Daily Science Report for 11 August 2014
LOCATION: Hole U1440B (28°26.99′N, 142°45.22′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: We continued to pull the drill string from the hole and at 0735 h it cleared the rotary table on the rig floor, ending Hole U1440A. Preparations started for casing operations, which will follow a new installation method. Our goal is to install the entire reentry system (reentry cone and casing string) while simultaneously drilling the hole in one step, potentially saving several days of operation time. The preparations included making up the casing running tool, moving the reentry cone onto the moonpool doors beneath the rotary table, and assembling the casing string. The 99 m long casing string is composed of seven joints of 10.75 inch casing welded together, a transition piece with dimensions of 10.75 inch on one end and 16 inch on the other, and a 16 inch casing hanger. By 1700 h, the casing string had been assembled and latched into the reentry cone. The next step was to make up the bit, underreamer, and mud motor assembly and lower it through the reentry cone and casing. The mud motor will enable the underreamer and bit to rotate during drilling while keeping the casing stationary. The reentry cone was lowered through the moonpool at 2130 h and by the end of the day had reached 1059 m below rig floor.
Cores 13X–14X were sampled for shipboard samples.
Moisture and density measurements were completed for Hole U1440A.
Thin sections from the igneous rock pieces recovered in Cores U1440A-13X and 14X were examined and the rocks were confirmed to be aphyric to sparsely porphyritic basalts.
Cores 6H–13X were examined for calcareous nannofossils. Cores 6H–10H were barren. Core 11H contains nannofossils from latest Oligocene Zone CN19b. Nannofossils in Cores 12H and 13X require further examination.
All core section halves from Hole U1440A have been measured for their remanent magnetization. Thermal demagnetization of a few discrete samples continues.
The 25 interstitial water samples collected from Holes U1439A and U1440A were analyzed via ion chromatography for Cl–, Br–, SO42–, Na+, K+, Ca2+, and Mg2+. These samples were also measured for phosphate via UV/VIS spectrophotometry. Bulk rock sediment samples were prepared for CHNS analyses.
Daily Science Report for 10 August 2014
LOCATION: Hole U1440A (28°26.99′N, 142°45.22′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: Cores U1440A-7H to 14X were cored from 49.0 to 106.1 m below seafloor (mbsf), with 48.2 m recovered (84% recovery). Hard formation was encountered while trying to recover Core 12H, and a few igneous rock fragments were recovered in the bottom of Cores 13X and 14X. The decision was made to terminate Hole U1440A and to prepare for the installation of a reentry system and RCB coring. The drill string was pulled out of the hole, clearing the seafloor at 2140 h and reaching a depth of 3646 m below rig floor by the end of the day. Heave continued to be a problem for most of the day, impacting core quality and resulting in some lost time needed for core line repairs. An abandon boat and fire drill was held at 1300 h.
Whole-Round Multisensor Logger (WRMSL) track, natural gamma ray (NGR), and thermal conductivity measurements were completed on all cores from Hole U1440A. Moisture and density measurements were completed for Hole U1439A, and are in progress for Hole U1440A.
Cores U1440A-1H to 14X were split, imaged on the Section Half Imaging Logger (SHIL), and measured on the Section Half Multisensor Logger (SHMSL). Cores 1H–12H were sampled for shipboard and personal samples.
Sediments in Cores U1440A-5H to 11H are dominated by brownish, partly coarse, matrix supported volcanogenic debris alternating with pinkish brown mud and occasional grayish, normally graded ash layers.
Thin sections from the igneous rock pieces recovered in Cores U1439A-20X to 23X were examined and the rocks were determined to be boninites with orthopyroxene phenocrysts in a matrix of clear glass. Preliminary examination of the Hole U1440A igneous rock fragments indicates that these are aphyric basalts.
Hole U1440A sediments are mostly undisturbed and have subhorizontal bedding planes. A few cores in the middle of the section were impacted by the high heave conditions.
Cores U1440A-1H to 5H contain calcareous nannofossil assemblages, although ages are tentative below Core 1H. The maximum age of Core 5H is ~2.49 m.y., which places it in the late Pleistocene.
Core section halves from Hole U1440A have been demagnetized and measured through Core 10H. The demagnetization of discrete samples is in progress.
Headspace gas samples for safety monitoring and interstitial water (IW) samples were analyzed from Cores U1440A-7H to 12H. The six IW samples were analyzed for chlorine content, salinity, alkalinity, and pH.
Daily Science Report for 9 August 2014
LOCATION: Hole U1440A (28°26.99′N, 142°45.22′E, 4775 m water depth; proposed Site BON-1A)
SCIENCE UPDATE: The ship arrived at Site U1440 (proposed Site BON-1A) at 0615 h after a transit of 8.2 mi completed in dynamic positioning mode. The drill string was extended to 4757 m below rig floor and Hole U1440A was spudded at 1255 h. Cores U1440A-1H to 6H were cored from 0 to 49.0 m below seafloor (mbsf), with 48.4 m recovered (99% recovery). Core 6H was the last oriented core as a result of the extreme heave conditions (3.8 m average, 4.4 m maximum).
Whole-Round Multisensor Logger (WRMSL) track, natural gamma ray (NGR), and thermal conductivity measurements were completed on Cores U1440A-1H to 4H. Moisture and density measurements were completed on Cores U1439A-16X, 18X, and 19X and Cores U1440A-1H and 2H.
Cores U1439A-17X to 23X were split, imaged on the Section Half Imaging Logger (SHIL) and measured on the Section Half Multisensor Logger (SHMSL). Cores 18X-19X were sampled for shipboard and personal samples with sampling of the remaining cores deferred until later.
The lower sediment portion of Hole U1439A includes reworked tuffs mixed with pelagic ooze. The transition zone to igneous basement is characterized by a greenish hyaloclastite, basalt-derived sand, and granule conglomerate. Pieces of igneous rock in Cores U1439A-20X to 23X were described macroscopically and thin sections are in preparation.
Cores U1439A-16X to 20X contained 61 structural features, and Cores U1440A-1H and 2H contained seven features. Tectonic deformation structures are common in Hole U1439A from 155 mbsf to the basement interface. In Hole U1440A, the sediments are undisturbed down to 12 mbsf.
All core section halves from Hole U1439A have been demagnetized in an alternating field (AF) and measured on the superconducting cryogenic magnetometer (SRM). Almost 100 discrete samples have been AF demagnetized and measured on the Spinner magnetometer, with a few samples that require thermal demagnetization still being measured.
Headspace gas samples for safety monitoring and six interstitial water (IW) samples were analyzed from Cores U1440A-1H to 6H.
Daily Science Report for 8 August 2014
LOCATION: Hole U1439A (28°24.45′N, 142°36.51′E, 3128 m water depth; proposed Site BON-2A)
SCIENCE UPDATE: Coring resumed at 0430 h following repairs to the top drive hydraulic hose. Cores U1439A-19X to 23X were cored from 167.1 to 199.4 m below seafloor (mbsf), with 14.6 m recovered (45% recovery). Although the last four cores contained a mixture of igneous and sedimentary rocks, the hole was terminated at a suitable depth for setting casing in case we return here for deeper rotary coring. At 1520 h, the ship was offset 20 m to the east and a jet-in test was conducted in Hole U1439B to establish the length of the first casing string we will have to install if we return to this site. At 2030 h, the ship started the transit from Site U1439 to Site U1440 (proposed Site BON-1A).
Whole-Round Multisensor Logger (WRMSL) track measurements were completed on Cores 16X–23X, natural gamma ray (NGR) measurements on Cores 14X–23X, thermal conductivity measurements on Cores 14X–23X, and moisture and density measurements on Cores 8H–15X.
Cores 8H–16X were split, imaged on the Section Half Imaging Logger (SHIL) and measured on the Section Half Multisensor Logger (SHMSL), and sampled for shipboard and personal samples.
Below Core 9H, the lithology returns from a more volcanogenic provenance to a pelagic environment dominated by nannofossil ooze, calcareous clay, and occasional sandy layers with foraminifers. Beginning with Core 15X, the sediments are again influenced by volcanic detritus evident by abundant dark brown, centimeter-thick, sandstone layers very rich in volcanic material. Igneous rock was recovered in the core catcher of Core 21X at a depth of ~179 m, but has not been described yet.
Cores 5H–15X contained 27 structural features. Drilling-induced deformation is prominent below a depth of 108 mbsf and occurs primarily as core flank deformation, rotary shear deformation, and core expansion, which continues several hours after the core reaches the lab. Bedding planes remain subhorizontal.
Based on nannofossils, Core 15X is placed in the middle Miocene and Core 20X, the deepest sediment sample, is dated tentatively to the lower early Eocene (~35–38 Ma).
Headspace gas samples for safety monitoring were analyzed from Cores 18X–23X.
Daily Science Report for 7 August 2014
LOCATION: Hole U1439A (28°24.45′N, 142°36.51′E, 3128 m water depth; proposed Site BON-2A)
SCIENCE UPDATE: Cores U1439A-1H to 18X were cored from the seafloor to 167.1 m below seafloor, with 156.1 m recovered (93% recovery).
Whole-Round Multisensor Logger (WRMSL) track measurements were made on Cores 1H–15X, natural gamma ray (NGR) measurements on Cores 1H–13X, thermal conductivity measurements on Cores 1H–13X, and moisture and density measurements on Cores 1H–7H.
Cores 1H–7H were split, imaged on the Section Half Imaging Logger (SHIL) and measured on the Section Half Multisensor Logger (SHMSL), and sampled for shipboard and personal samples.
Cores 1H–7H are dominated by alternations of brownish to beige, muddy, sandy and clayey nannofossil ooze with calcareous mudstones, sometimes with foraminifers. Intercalated, centimeter-sized, predominantly felsic, grayish to whitish brown ash layers are found throughout. Bioturbation is abundant. Toward the bottom of Core 6H the composition of the sediment changes to a fine-grained matrix suggestive of a change to a more mafic volcanogenic provenance.
Nine structural features were measured in the working halves of Cores 1H–4H. Drilling-induced deformation is minimum to absent. Bedding plane are mostly horizontal. Three distinct pyroclastic (ash?) layers are concordant with the horizontal bedding.
Nannofossils are abundant and display diverse assemblages in Cores 1H–4H. The bottom of Core 4H has an approximate lower late Pliocene age of 2.8 m.y. (Zone CN12a).
Headspace gas samples for safety monitoring were analyzed from Cores 1H–18X and 12 interstitial water (IW) samples were analyzed from Cores 1H–16X.
Daily Science Report for 6 August 2014
LOCATION: Hole U1439A (proposed Site BON-2A; 28°24.45′N, 142°36.51′E)
SCIENCE UPDATE: The JOIDES Resolution arrived at Site U1439 (proposed Site BON-2A) at 0324 h after a transit of 457 nmi that was completed in 40.4 h. Most of the day was spent assembling the advanced piston corer/extended core barrel (APC/XCB) bottom-hole assembly and the drill pipe that make up the drill string and lowering it through the 3.1 km water column. When we were ready to spud Hole U1439A at 1600 h, the sinker bars got stuck and core line was spooled off the drum, requiring two hours to repair. After an initial unsuccessful attempt to obtain a mudline core, Hole U1439A was spudded at 2340 h.
Core describers spent the day training on the Section Half Imaging Logger (SHIL) and the Section Half Multisensor Logger (SHMSL) in preparation for the first core. A science meeting was held at midday to discuss operations options depending on where Hole U1439A falls in the IBM forearc volcanic stratigraphy model.
Daily Science Report for 5 August 2014
LOCATION: In transit to Site U1439 (proposed Site BON-2A)
SCIENCE UPDATE: The expedition management team and members of the ship’s crew met to discuss the operations plan for both primary sites as the sedimentary section at both sites will be cored first. The scientists were introduced to the software used to take core samples. All laboratory teams worked on their Methods drafts. The sedimentology/structural geology teams worked on their core description terminology and display templates. During the midday shift crossover, the scientists attended a talk on tephrochronology and its application to investigating climate-volcano connections, as well as a talk on ophiolite-related sediments in Cyprus. Our estimated time of arrival at Site U1439 is 0400 h on 6 August.
Daily Science Report for 4 August 2014
LOCATION: In transit from Yokohama, Japan, to Site U1439 (proposed Site BON-2A)
SCIENCE UPDATE: This was our last day in port. An Abandon Boat Drill was conducted at 0800 h to familiarize everyone on board with their muster stations. Immigration authorities cleared the scientists and crew for departure at 0900 h. The last line was released at 1100 h and the vessel got underway for Site U1439 (proposed Site BON-2A). The scientists spent the rest of the day enjoying the departure and adjusting to their shifts and sea state. Our estimated time of arrival at Site U1439 is 0600 h on August 6.
Daily Science Report for 3 August 2014
LOCATION: Honmoku B3-4 berth, Yokohama, Japan
SCIENCE UPDATE: The Expedition Project Manager started the day’s activities with a presentation on the reports that need to be created on board, the IODP depth scales that will apply to our data sets, and some of the database reporting tools available. The only other presentation for the day was given by the two Education Officers, who invited the science party to participate in the various outreach activities being planned. Most scientists spent the remainder of the morning in the Core Laboratory, looking at legacy core from DSDP Leg 60 and discussing core description templates. The afternoon was free of activities so that scientists could enjoy their last day on shore. The ship is scheduled to depart at 1030 h tomorrow (4 August), with the Captain watching the progress of typhoon Halong to our southwest.
Daily Science Report for 2 August 2014
LOCATION: Honmoku B3-4 berth, Yokohama, Japan
SCIENCE UPDATE: The scientists spent the morning presenting their research plans and were able to arrive at a cohesive expedition sampling plan. The Operations Superintendent and Logging Staff Scientist gave presentations on the coring and logging tools available and the operations and logging plans of the expedition. Science teams continued working in the labs. The Sample Allocation Committee met to discuss shore-based requests. The Curator, Expedition Project Manager, and various scientists formulated a shipboard sampling plan for the sediments that we expect to start coring around August 7. A delegation from the Tokyo National Museum of Nature and Science visited the ship to start planning a live event for the end of August.
Daily Science Report for 1 August 2014
LOCATION: Honmoku B3-4 berth, Yokohama, Japan
SCIENCE UPDATE: The day’s activities started with personal introductions from all scientists and technical staff. Following those, the chief scientists talked about the regional geology and the scientific objectives. The Expedition Project Manager gave a presentation on what we need to produce on board and how we are going to accomplish it. After lunch, scientists were introduced to how core flows through the laboratories and sampling methods. The remainder of the day was spent introducing each laboratory team to the instruments and procedures used in core description, paleontology, physical properties, paleomagnetism, and geochemistry.
Daily Science Report for 31 July 2014
LOCATION: Honmoku B3-4 berth, Yokohama, Japan
SCIENCE UPDATE: The Expedition 352 Scientists and Siem Offshore crew boarded the vessel. The scientists spent the afternoon with lab tours and Life at Sea, Safety, and Information Technology orientations. The technical staff continued offloading and loading freight. The XRF instrument and the through-pipe backup camera system arrived.
Daily Science Report for 30 July 2014
LOCATION: Honmoku B3-4 berth, Yokohama, Japan
SCIENCE UPDATE: IODP Izu-Bonin-Mariana (IBM) Forearc Expedition 352 began with the first line ashore at 1042 h at Honmoku B3-4 berth in Yokohama, Japan. Port call activities started with lab crossover and safety training of IODP-USIO technical staff, incoming/outgoing freight, and the embarkation of the Expedition 352 Chief Scientists, Expedition Project Manager, and Logging Staff Scientist.
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