IODP Expedition 344

Costa Rica Seismogenesis Project,
Program A Stage 2 (CRISP-A2)

Daily Science Report for 30 November 2012

LOCATION: Hole U1413C (8°44.4482′N, 84°6.7993′W, 540 m water depth; proposed Site CRIS-13B)

SCIENCE UPDATE: The day started with continued efforts to prepare Hole U1413C for logging. The hole was washed down from 470 to 582 mbsf, encountering several tight spots that required the hole to be swept with mud. The bit was released at 0630 h and the end of the drill string was placed at 103 mbsf. The first logging run with the triple combo tool string started at 1045 h and was completed by 1430 h. Even though hole conditions did not allow the tools to reach the deeper portion of the hole, useful logging data were collected between 103 and 182 mbsf. A second run followed with the Ultrasonic Borehole Imager (UBI) tool string between 1430 and 1930 h. The final run with the Formation MicroScanner (FMS) tool string was completed by 2220 h and the logging tools were rigged down. The drill string was pulled out of the hole, clearing the seafloor at 2340 h, so that the vessel could be secured for the transit back to Site U1412. The lithology of Cores 27R to 43R at the bottom of Hole U1413C showed a major change toward massive, fine- to medium-grained sandstones that are characterized by abundant magmatic and sedimentary lithic fragments, as well as common occurrences of feldspar, foraminifers, and glass fragments and rare to common amphibole, chlorite, pyroxene, and glauconite. The decimeter to meter thick, slightly normally graded sandstone beds show some lamination in the uppermost part as well as the occurrence of gastropods and reworked, well-rounded carbonate clasts. Two videoconferences were held with high school students in Lakeside, California.

Daily Science Report for 29 November 2012

LOCATION: Hole U1413C (8°44.4482′N, 84°6.7993′W, 540 m water depth; proposed Site CRIS-13B)

SCIENCE UPDATE: Cores U1413C-36R to 43R were recovered from 507.8 to 582.2 mbsf with 63.2 m recovered (85%). Overall, 313.9 m was recovered at Hole U1413C out of 404.2 m cored (78%). Coring was terminated at 1400 h and the hole was prepared for logging. The drill string was raised to 88 mbsf and a wiper trip was conducted down to 250.6 mbsf, where an obstruction was encountered at 1800 h. The top drive was picked up and by midnight the hole had been washed down to 499 mbsf. The lithology stayed the same until Core 27R, when the silty claystone changed to a siltstone that is interrupted from time to time by several-centimeter thick foraminifer- and shell-rich sandstones. From Core 31R on, with a peak occurrence in Core 33R, horizons with well-rounded reworked matrix clasts together with abundant gastropods are observed and get more frequent with depth. Nannofossils indicate an early Pleistocene age for the bottom of Hole U1413C. Two videoconferences were held with high school students in New Point Richey, Florida, and elementary school students in Lakeside, California. A 3-way videoconference was held with students at the University of Chiba, Japan, and Expedition 338 scientists on the Chikyu.

Daily Science Report for 28 November 2012

LOCATION: Hole U1413C (8°44.4482′N, 84°6.7993′W, 540 m water depth; proposed Site CRIS-13B)

SCIENCE UPDATE: Cores U1413C-20R to 35R were recovered from 352.6 to 507.8 mbsf with 138 m recovered (89%). Core description was completed through Core 24R. The lithology is dominated by mildly calcareous, greenish gray silty claystone to siltstone, with more frequent occurrences of wood, shell, and gastropod fragments. Nannofossils continue to indicate an early to middle Pleistocene age. Two videoconferences were held with high school students in Mechanicsville, Virginia, and middle school students in Los Angeles, California.

Daily Science Report for 27 November 2012

LOCATION: Hole U1413C (8°44.4482′N, 84°6.7993′W, 540 m water depth; proposed Site CRIS-13B)

SCIENCE UPDATE: Cores U1413C-3R to 19R were recovered from 187.7 to 352.6 mbsf with 105.7 m recovered (64%). The first few cores of Hole U1413C have the same lithology as the bottom of Hole U1413A, which is characterized by a monotonous series of strongly consolidated, mildly calcareous, greenish gray silty claystone to siltstone. A few intercalated centimeter-thick ash layers become more frequent with depth. Starting with Core 6R, there are rare layers of sandstone as well as wood and leaf fragments. Nannofossils from the bottom of Hole U1413A and the top of Hole U1413C indicate an early to middle Pleistocene age. One videoconference was held with high school students in Mechanicsville, Virginia.

Daily Science Report for 26 November 2012

LOCATION: Hole U1413B (8°44.4593′N, 84°6.7992′W, 540 m water depth; proposed Site CRIS-13B);
and Hole U1413C (8°44.4482′N, 84°6.7993′W, 540 m water depth)

SCIENCE UPDATE: After pulling the drill string out of Hole U1413A, a short hole was cored for geochemical analyses. The vessel was offset 20 m to the east and Hole U1413B was spudded at 0055 h. Cores U1413B-1H to 3H were recovered from 0 to 25.6 mbsf with 27.4 m recovered (107%). The drill string was pulled out of the hole, clearing the rotary table at 0550 h, and the APC/XCB coring assembly was changed to an RCB coring assembly. The vessel was offset 20 m to the south, the drill string was lowered to just above the seafloor, and Hole U1413C was spudded at 0940 h. By 2130 h, drilling without recovery had reached 178 mbsf, the coring depth reached in Hole U1413A. Cores U1413C-2R to 3R were recovered from 178.0 to 197.4 mbsf with 10.3 m recovered (53%).

The lithology at the bottom of Hole U1413A remained the same but several larger ash layers interrupted the monotonous series of greenish grayish clay to silt. The lithology of Hole U1413B started with a soupy, brownish green silty clay. This was followed by an interval of intercalated, calcareous, light greenish grayish clay to silt that also contained some hardened carbonate clasts. At the bottom of Hole U1413B, the lithology returned to a greenish gray silty clay with abundant centimeter-thick sequences of sand as in Hole U1413A. Nannofossils and radiolarians indicate a middle–late Pleistocene age for the bottom of Hole U1413A. Physical properties and paleomagnetic measurements continued throughout the day. The cores from Hole U1413B were sampled at high resolution for geochemical analyses of the sulfate/​methane interface. One videoconference was held with middle school students in Kentwood, Michigan.

Daily Science Report for 25 November 2012

LOCATION: Hole U1413A (8°44.4593′N, 84°6.8095′W, 540 m water depth; proposed Site CRIS-13B)

SCIENCE UPDATE: Cores U1413A-10H to 26X were recovered from 79.5 to 189.1 mbsf with 106.1 m recovered (97%). In Core 6H, the lithology changes first from the dark greenish gray silty clay with abundant centimeter-thick sequences of millimeter-thick, turbiditic, fine-sand laminae to a brownish green chaotic mixture of silty clay with dark gray sands, and then abruptly into a light greenish gray clay with few variations in grain size to silty clay. In the following cores, this monotonous lithology is interrupted by rare ash layers, and deeper than Core 12H the sediments show indication of gas expansion. Nannofossils and radiolarians indicate an Upper Pleistocene age. Physical properties and paleomagnetic measurements as well as pore fluid geochemical analyses continued throughout the day. As the sediments became very consolidated and the rate of penetration slowed down considerably, we decided to terminate this APC/XCB hole. Overall recovery in Hole U1413A was 187.3 m out of 189.1 m cored (99%). The immediate plan is to core a shallow hole for geochemical analyses, followed by a deeper RCB hole.

Daily Science Report for 24 November 2012

LOCATION: Hole U1413A (8°44.4593′N, 84°6.8095′W, 540 m water depth; proposed Site CRIS-13B)

SCIENCE UPDATE: The JOIDES Resolution arrived at Site U1413 (proposed Site CRIS-13B) at 2330 h yesterday (time changed from previous daily report). The operations plan here includes coring two holes (0–600 and 600–1430 mbsf) and logging both, but will be revisited in a few days. An APC/XCB bottom-hole assembly was put together and Hole U1413A was spudded at 0635 h. Cores U1413A-1H to 9H were recovered from 0 to 79.5 mbsf with 81.2 m recovered (102%). The lithology consists of greenish gray silty clay with abundant centimeter-thick sequences of millimeter-thick, turbiditic, fine-sand laminae that typically show sharp basal contacts and gradational upper boundaries with the background clay. Sediments are dominated by terrigenous components and contain abundant foraminifers, especially in the sandstones. A few ash layers and pods from Costa Rican volcano eruptions are also present in the cores. Nannofossils and radiolarians indicate an Upper Pleistocene age. Physical properties measurements started in the late morning, after the cores had equilibrated to room temperature. APCT-3 formation temperature measurements were taken with Cores 3H, 5H, 6H, 7H, and 8H, and the FlexIt orientation tool was deployed with all APC cores. Repairs required by a broken wireline and a malfunctioning top drive hydraulic tilt cylinder had to be carried out between 1200 and 2000 h.

Daily Science Report for 23 November 2012

LOCATION: Hole U1412C (8°29.1700′N, 84°7.7467′W, 1964 m water depth; proposed Site CRIS-9A)

SCIENCE UPDATE: Cores U1412C-8R to 10R were recovered from 357.9 to 387.0 mbsf with 14.7 m recovered (51%). The lithology consists of greenish gray silty clay. Nannofossils indicate a Pleistocene age. Following the recovery of Core 10R, drilling conditions deteriorated with torque reaching 800 amps. After several hours spent trying to clean the fill at the bottom of the hole and not being able to get deeper than 307 mbsf, the science party decided to abandon Hole U1412C and proceed to proposed Site CRIS-13B. The drill string was pulled out of the hole, clearing the rotary table at 2115 h, the beacon was retrieved, and the rig floor was secured for transit. The JOIDES Resolution got underway to Site U1413 (CRIS-13B) at 2330 h.

Daily Science Report for 22 November 2012

LOCATION: Hole U1412C (8°29.1700′N, 84°7.7467′W, 1964 m water depth; proposed Site CRIS-9A)

SCIENCE UPDATE: Drilling without recovery in Hole U1412C continued to 300 mbsf, the depth coring reached in Hole U1412B. The hole was swept with 50 barrels of mud in preparation for coring. Cores U1412C-2R to 7R were recovered from 300.0 to 357.9 mbsf with 21.9 m recovered (38%). The lithology consists of brownish siltstone with a carbonate matrix in Cores 2R–5R, followed by greenish gray silty clay in Cores 6R–7R. Nannofossils indicate a Miocene age for Cores 2R–5R, followed by a reversal to Pleistocene age for Cores 6R–7R. The American Thanksgiving holiday was celebrated with an elaborate midday meal.

Daily Science Report for 21 November 2012

LOCATION: Hole U1412C (8°29.1700′N, 84°7.7467′W, 1964 m water depth; proposed Site CRIS-9A)

SCIENCE UPDATE: An RCB coring assembly was made up with a 9⅞ inch bit and the drill string was lowered to 1953 m below the rig floor. Hole U1412C was spudded at 0730 h and the rest of the day was spent drilling without recovery to 232 mbsf. Walter Kurz gave a talk on Alpine geology and Mediterranean tectonics. One videoconference was held with middle school students in Washington, DC.

Daily Science Report for 20 November 2012

LOCATION: Hole U1412B (8°29.1599′N, 84°7.7512′W, 1964 m water depth; proposed Site CRIS-9A)

SCIENCE UPDATE: We continued preparing Hole U1412B for logging. Following extensive hole cleaning overnight, the end of the drill pipe was set at 91 mbsf and the triple combo tool string was rigged up and run into the hole at 1040 h. However, the tool string encountered an obstruction ~2 m above the end of the drill pipe and after several failed attempts to lower the tool string, logging operations were terminated at 1600 h. High torque and overpull were recorded while trying to pull the drill pipe out of the hole. The vessel was offset 20 m to the north-northeast for operations at Hole U1412C and the rest of the day was spent pulling the drill string to the rig floor so that the XCB coring assembly could be switched to an RCB assembly. Hole U1412B paleontology samples are still being processed but all other measurements have been completed for Holes U1412A and U1412B. Two videoconferences were held with middle school students in Columbia, South Carolina.

Daily Science Report for 19 November 2012

LOCATION: Hole U1412B (8°29.1599′N, 84°7.7512′W, 1964 m water depth; proposed Site CRIS-9A)

SCIENCE UPDATE: Cores U1412B-13X to 20X were recovered from 243.1 to 304.3 mbsf with 1.24 m recovered (2%). Core description was limited by the poor recovery to a few lithified clasts in the core catchers. These clasts are dominated by nannofossil ooze that contains diatoms, sponge spicules, radiolarians, and foraminifers as well as rare feldspar crystals. Nannofossils and radiolarians indicate a Middle Miocene age. Limited measurements continued throughout the day. A videoconference was held with high school students in New Egypt, New Jersey.

The drill pipe became stuck at 1815 h. After working the pipe free with 90 klbs of overpull and 800 amps of torque, we were not able to wash back down to the total depth of the hole at 304.3 mbsf. The decision was made to end coring operations and to prepare Hole U1412B for logging. The hole was pumped with a 50-barrel sweep of high viscosity mud, the pipe was raised to 231 mbsf, and another four mud sweeps (160 barrels) in an attempt to clean it.

Daily Science Report for 18 November 2012

LOCATION: Hole U1412B (8°29.1599′N, 84°7.7512′W, 1964 m water depth; proposed Site CRIS-9A)

SCIENCE UPDATE: Cores U1412B-4X to 12X were recovered from 165.5 to 243.1 mbsf with 17.1 m recovered (22%). Before retrieving Core 12X the pipe got stuck at 233 mbsf and had to be pulled with 140 klbs of overpull and 700 amps of torque. The lithology is dominated by a dark greenish to greenish gray clay with some smaller variations in grain size to silty clay as in the lower portion of Hole U1412A. Some intervals are disturbed due to the disassociation of gas hydrate in the sediments. Starting with Core 8X there is a sharp change in lithology and color toward a 50-cm thick whitish diatom ooze with nannofossils, grading into a brownish nannofossil ooze with diatoms by Core 12X. Nannofossils and radiolarians indicate a Late Miocene age at the bottom of Core 8X. Measurements and sampling continued throughout the day.

Daily Science Report for 17 November 2012

LOCATION: Hole U1412B (8°29.1599′N, 84°7.7512′W, 1964 m water depth; proposed Site CRIS-9A)

SCIENCE UPDATE: APC Core U1412B-1H was recovered from 0 to 6.7 mbsf with 6.7 m recovered (101%), followed by drilling without recovery with a center bit from 6.7 to 155.8 mbsf. The bit was changed to an XCB bit at 1700 h and Core 3X was recovered from 155.8 to 165.5 mbsf with 3.23 m recovered (33%). Measurements continued throughout the day on Hole U1412A samples and Core U1412B-1H. A party was held late in the day to celebrate the midpoint of the expedition.

Daily Science Report for 16 November 2012

LOCATION: Hole U1412A (8°29.3294′N, 84°7.6686′W, 1920 m water depth; proposed Site CRIS-9A);
and Hole U1412B (8°29.1599′N, 84°7.7512′W, 1964 m water depth)

SCIENCE UPDATE: Cores U1412A-24X to 25X were recovered from 180.9 to 200.3 mbsf with 11.25 m recovered (58%). Drilling conditions became increasingly difficult with the drill pipe having to be raised to recover the core barrels. Given these difficulties and the time required to retrieve cores we decided to abandon this hole and offset to a new location. During the recovery of the final core barrel the wireline parted. Hole U1412A was pumped with 49 barrels of heavy mud, the drill pipe was raised above the seafloor, and the vessel offset 350 m south-southwest in dynamic positioning mode. Upon arrival at Hole U1412B at 1435 h, the crew spent several hours fishing the final core barrel from the previous hole (U1412A) and restringing the wireline in the derrick. Hole U1412B was spudded at 2350 h to recover an APC mudline core and to drill without recovery down to 160 mbsf before resuming coring.

All cores from Hole U1412A have been described and sampled. The lithology between Cores 11X and 25X continued to be dominated by a dark greenish gray clay with some horizons increasing in grain size up to silty clay. Two ash layers were observed in Core 17X. Cores near the bottom of the hole are highly disturbed due to the disassociation of gas hydrate in the sediments. Microfossils in core catcher samples indicate a Lower Pleistocene age for the entire cored interval. Whole-round, section-half, and discrete sample measurements continued throughout the day. Two videoconferences were held with school students in Linconton, North Carolina, and Orland Park, Illinois.

Daily Science Report for 15 November 2012

LOCATION: Hole U1412A (8°29.3294′N, 84°7.6686′W, 1920 m water depth; proposed Site CRIS-9A)

SCIENCE UPDATE: Cores U1412A-8H to 23X were recovered from 57.6 to 180.9 mbsf with 100.1 m recovered (81%). The FlexIt orientation tool was used with Cores 8H–15H, at which point drilling conditions required switching from the APC to the XCB coring assembly. The last APCT-3 temperature measurement was taken with Core 8H. Cores 1H–11H have been described and sampled. The lithology is dominated by dark greenish to greenish gray clay, and five ash layers were found. The sediments are at times deformed by gas expansion, and starting with Core 8H some intervals exhibit deformation structures typical of gas hydrate-bearing sediments. Microfossils in core catcher samples so far indicate a Lower Pleistocene age. Whole-round, section half, and discrete sample measurements continued throughout the day. Three videoconferences were held with school students in Dover, New Hampshire, and Portland, Oregon.

Daily Science Report for 14 November 2012

LOCATION: Hole U1412A (8°29.3294′N, 84°7.6686′W, 1920 m water depth; proposed Site CRIS-9A)

SCIENCE UPDATE: The JOIDES Resolution left Site U1380 at 0100 h and arrived at Site U1412 (proposed Site CRIS-9A) at 0200 h. The operations plan here includes coring two holes (0–500 and 490–980 mbsf) and logging both. A meeting was held to discuss the Site U1380 scientific results. After three unsuccessful attempts at recovering the mudline, Hole U1412A was initiated at 1520 h. Cores U1412A-1H to 7H were recovered from 0 to 57.6 mbsf with 58.7 m recovered (102%). The FlexIt orientation tool was used with Cores 1H–7H, and APCT-3 formation temperature measurements were taken with Cores 3H, 5H, and 7H. Physical properties measurements started in the evening, after the cores had equilibrated to room temperature.

Daily Science Report for 13 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: We continued our efforts to log Hole U1380C. The day started trying to wash down from 732 to 800 mbsf. By 0615 h we had reached 781 mbsf but because progress was too slow, we decided to stop short of the 800 m total depth. In preparation for logging, we circulated the hole clean with high-viscosity mud, raised the drill string to 768 mbsf, dropped the bit in the hole, displaced the hole with mud, and raised the end of the drill pipe up to 443 mbsf (~10 m above the inferred end of the casing). We rigged up the triple combo tool string for the third time and lowered into the hole at 1310 h. The tool string encountered a similar obstruction as before at 462 mbsf and could not advance any further. Despite a number of operational steps, including circulating, rotating the drill string, and lowering the drill string 10 m, the logging tools could not pass an obstruction at 443 mbsf, so we decided to terminate operations at Site U1380. After plugging the hole with cement, the drill pipe was pulled out of the hole and the rig floor was secured for the short transit to Site U1412 (proposed Site CRIS-9A). Scientists spent the day finalizing measurements and working on the Site U1380 reports.

Daily Science Report for 12 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: We continued our efforts to log Hole U1380C. The day started with the triple combo tool string being lowered into the hole but another obstruction was encountered at 458 mbsf and the tools had to be pulled out of the hole. The drill pipe was lowered further but could not advance past 496 mbsf and had to be pulled back to 457 mbsf with 20 klbs overpull. In order to better clean the hole for logging, the drill string was pulled all the way out of the hole, reaching the rig floor at 0725 h, and a new BHA was assembled with a used RCB bit. The drill string was lowered to just above the seafloor, the subsea camera was deployed, and Hole U1380C was reentered at 1015 h. The drill pipe was advanced to 65 mbsf—where it possibly encountered the top of the 10¾ inch casing string—and then eventually down to 496 mbsf by 1400 h. The rest of the day was spent washing down from 496 to 732 mbsf.

Core description and sampling were completed through Core 52R (800 mbsf). The lithology stayed the same, consisting of a monotonous interval of silty claystone interrupted only rarely by layers of centimeter-sized, greenish gray, fine-grained sandstone. Most discrete sample measurements have been completed.

Daily Science Report for 11 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: Cores U1380C-50R to 52R were recovered from 782.6 to 800.0 mbsf with 11.1 m recovered (64%). Coring was terminated at the depth approved by the Environmental Protection and Safety Panel (EPSP). In preparation for logging operations, the drill pipe was raised to 486 m below rig floor, the vessel was offset 20 m north, and the bit was released at 0855 h. Hole U1380C was reentered at 1005 h and the drill pipe was lowered to 336 mbsf. After a safety meeting with the drill crew and Schlumberger engineer, the triple combination-Ultrasonic Borehole Imager (UBI) tool string was rigged up and lowered into the hole at 1530 h. When the tool string encountered an obstruction at 398 mbsf, the decision was made to try to clean the hole with the drill pipe. The logging tools were brought back to the surface at 1820 h and the drill pipe was lowered to 466 mbsf by 2115 h. The pipe was raised back to 379 mbsf and the triple combo string (without the UBI) was rigged up again. The day ended with the tool string being lowered into the hole.

Core description and sampling were completed through Core 49R (780 mbsf). The lithology is similar to that encountered before Core 30R and consists of a moderately bioturbated, monotonous sequence of dark greenish gray clayey siltstone with several, up to 40 cm thick, beds of massive, normally graded, fine to coarse sandstones. Contact boundaries are mostly erosive, and the background sediment as well as the sandstones contain predominantly terrestrial matter. Biogenic matter, with the exception of charcoal, is very rare or absent. In Core 46R, two large beds of conglomerate were found lying directly on top of the reddish brown silty claystone of Core 47R. Below Core 47R, the sedimentary sequence returns again to a monotonous interval of silty claystone interrupted only rarely by layers of centimeter-sized, greenish gray, fine-grained sandstone. Normal and reverse faults are present throughout the interval and bedding is slightly inclined. Benthic foraminifers are rare in the lower portion of the hole and nannofossils tentatively indicate that the base of the hole is Zone NN17.

Daily Science Report for 10 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: Cores U1380C-35R to 49R were recovered from 709.7 to 782.6 mbsf with 49.8 m recovered (68%). Core description and sampling are complete through Core 36R (717 mbsf). The lithology is dominated by a moderately bioturbated, monotonous sequence of very dark greenish gray clayey siltstone with several beds of normal graded sandstones up to 10 cm thick. The matrix and sandstone beds contain abundant to dominant, mostly volcanogenic, lithic fragments, common feldspar, glass, rare calcite, chlorite, amphibole, pyroxene, and rare biogenic material. Nannofossils are rare and foraminifers and diatoms are very rare to absent. Carbonaceous concretions and cemented breccia are rarely present but increase with depth and are often associated with the occurrence of carbonaceous-cemented fine conglomerates below Core 22R. From the lower part of Core 30R through Core 31R there is a reddish brownish unit composed of clayey siltstone interlayered with the lithified remnants of thick bedded sandstone to conglomerate layers. Normal and reverse faults are present throughout the interval and bedding is inclined.

Daily Science Report for 9 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: Cores U1380C-20R to 34R were recovered from 612.7 to 709.7 mbsf with 39.6 m recovered (41%). The lithology stays the same through Core 13R and is composed of massive greenish gray clayey siltstone alternating with silty claystone that grades into sandstone towards the bottom of the unit. Dispersed centimeter-sized sandy beds are present throughout the cored interval. The sediment is highly fractured between Cores 10R and 13R. A sharp lithologic boundary occurs with Core 14R (554 mbsf) and is characterized by poorly to weakly consolidated greenish green sand/​sandstone with abundant shell fragments and a matrix that is composed of feldspar, amphiboles, chlorite, and lithic fragments. Below this, the sedimentary section returns to a sequence of very dark greenish gray clayey siltstone with several beds of massive sandstone up to 10 cm thick. Normal faults are present throughout the described interval with a few reverse faults appearing in the lower part. Bedding and fissility are inclined in the upper part but fissility disappears below Core 29R. Calcareous nannofossil assemblages indicate that Zone NN18 continues through Core 24R but with lower abundance and poor preservation of microfossils.

Daily Science Report for 8 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: Cores U1380C-5R to 19R were recovered from 467.1 to 612.7 mbsf with 88.7 m recovered (61%). Cores U1380C-1R to 5R are dominated by massive dark-greenish gray clayey siltstone and some rare centimeter-sized sandy layers that increase with depth. This trend to coarser deposits continues in Cores 6R–8R with the occurrence of abundant decimeter-sized dark greenish gray beds. Individual beds have generally fining upward sequences starting with an erosional contact and centimeter-thick horizons of fine sandstone that transition into silty claystone at the top, which is often characterized by a moderately to highly bioturbated carbonaceous centimeter-scaled horizon. The downward increase in frequency of coarser intervals culminates in chaotic mixed, decimeter-sized intervals of sandstone, siltstone and clays (Core 8R). Shell fragments within the sediments are getting more common and ash layers are surprisingly rare. Structures in Cores 1R–6R are mainly normal faults; observed bedding and fissility is steeply inclined. Calcareous nannofossil assemblages indicate that the boundary between Zone NN19 and NN18 (at ~1.89 Ma) is between the core catcher samples of Cores 8R and 9R.

Daily Science Report for 7 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: At Hole U1380C we continued to pull the drill string out of the hole so that we could change the bottom-hole assembly (BHA) to a coring one. The remaining casing hanger and one joint of casing were put away and the rig floor was cleared of casing equipment. A coring BHA was made up with a 9⅞ inch bit and lowered to the seafloor. The subsea camera was deployed and Hole U1380C was reentered at 0900 h. The drill pipe encountered what is believed to be the top of the second casing string at 8 mbsf, which puts the bottom of the casing string at 398 mbsf. The subsea camera was retrieved and the drill pipe was advanced to 322 mbsf. A core barrel was dropped and the bit was positioned at 336 mbsf, where advancement had stopped the day before. The hole was washed down from 336 to 438 mbsf, with minor obstacles encountered at the very beginning and when the drill pipe exited the casing. The wash core was pulled to the surface at 1745 h and RCB coring resumed. By midnight, we had recovered Cores 2R-4R from 438 to 467 mbsf with 13.2 m recovered (45%).

Daily Science Report for 6 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: Today we continued trying to clean Hole U1380C with the underreamer so that the 10¾ inch casing could be installed. Drilling conditions became erratic at 236 mbsf (0045 h) and we had to pull the bit and underreamer out of the hole. When the bit cleared the rig floor, the underreamer was still intact but its arms could not be activated. We replaced the underreamer and lowered it to 371 m below the rig floor. Since we were lowering this through the middle of the 10¾ inch casing that was hung off the moonpool doors, we had to pick the casing up off the moon pool doors so that the subsea camera system could be deployed for reentry. However, shortly after launching the camera it became evident that the 10¾ inch casing string had failed just below the waterline. We continued to lower the camera system to the seafloor so that we could inspect the reentry cone. No casing could be seen on the seafloor, so we reentered Hole U1380C at 1357 h. After the camera system was recovered, we lowered bit to 336 mbsf (1945 h), but could not make further progress. It appears that the parted 390-m-long string of casing string traveled all the way down the drill string and into the hole. The bit could not pass through the lowermost ~60 m of casing. We decided to pull the underreamer out of the hole and plan to reenter the hole with an RCB coring bit to attempt washing through the lowermost part of the casing. However, it is possible that the lower part of the casing is too damaged to allow the bit to pass. At the end of the day, the underreamer had been pulled out of the hole and had reached just below the rig floor.

Daily Science Report for 5 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: Yesterday’s attempt to install 10¾ inch casing in Hole U1380C was not successful, so today we continued pulling the casing out of the hole. Once it was back up to the ship, the casing hanger was landed on the moon pool doors and the casing running tool was released. The stinger assembly was pulled out of the casing and the bit cleared the rig floor at 0425 h. We decided to temporarily put the 10¾ inch casing aside (hung on the moonpool doors) and to clean out the hole with a 14¾ inch underreamer with a 9⅞ inch pilot bit. The rest of the morning was spent lowering the drilling assembly to the seafloor and deploying the subsea camera system for reentry—which required picking the casing up off the moonpool doors during camera deployment and recovery. The drill pipe was lowered to 497 m, just above the seafloor, the vessel maneuvered over the re-entry cone, and Hole U1380C was reentered at 1438 h. After recovering the subsea camera, the top drive was picked up and by the end of the day Hole U1380C had been reamed from 51 to 217 mbsf.

Daily Science Report for 4 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: The Hole 1380C casing was landed on the moon pool doors and the casing running tool was released. A stinger assembly with a drill bit at the end was assembled inside the casing. The running tool was latched to the casing and the casing was lowered to the seafloor. The subsea camera was deployed, Hole U1380C was reentered with the casing assembly at 0745 h, and the camera was recovered. The casing was lowered to 179 mbsf, where a tight spot was encountered. The top drive was picked up and the casing was advanced to 377 mbsf, short of its target depth. All attempts to advance the casing, including pumping 10 barrels of mud and sweeping the hole clean, failed. The casing got stuck and had to be worked free with 120 klbs of overpull. The casing was raised with the top drive from 370 to 122 mbsf and the day ended with the top drive set back.

Daily Science Report for 3 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: Scientists finalized the Site U1381 reports. Hole U1380C was washed and reamed down to 438 mbsf between 0000 and 0200 h. Two 25-barrel sweeps of mud were circulated to condition the hole. The bit was raised with the top drive to 328 mbsf and the hole was observed for 15 minutes. The hole was washed down to 406 mbsf without rotation, and by 0600 h had been washed and reamed with rotation to 438 mbsf, where 10 m of fill was encountered. Two more 25-barrel sweeps of mud were circulated, followed by 225 barrels of heavy mud. The bit was raised with the top drive to 319 mbsf, the top drive was set back at 0900 h, and the rest of the drill pipe was pulled out of the hole. The bit cleared the rotary table at 1155 h. The casing running tool was assembled by 1315 h and the rig floor was prepared for running casing into the hole. First, the 10¾ inch casing shoe joint was made up, followed by 29 joints of casing by 2230 h. The assembled 10¾ inch casing string has a length of 404.4 m and weighs 40,000 lbs. The remainder of the day was spent attaching the running tool to the casing string.

Daily Science Report for 2 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: A meeting was held to discuss the décollement sampling plan at Site CRIS-9A, which will become Site U1412, and to develop strategies for recovering and preserving the thin (~10 cm or less) principal shear zone within. Scientists continued working on reports. At Hole U1380C, we continued waiting for the cement to set until 0900 h. The bit was run into the hole, passing through a tight interval at 153–163 mbsf, and could not be advanced past 175 mbsf. The top drive was picked up and the hole was washed and reamed to 347 mbsf, where the top of the cement plug was encountered. The cement plug was drilled from 347 to 386 mbsf between 1715 and 1930 h, one 25-barrel sweep of mud was circulated between 1930 and 2115 h, and the remaining cement down to 387 mbsf had been drilled by 2145 h. The hole was washed down from 384 to 415 mbsf during the remaining part of the day.

Daily Science Report for 1 November 2012

LOCATION: Hole U1380C (8°35.9879′N, 84°4.3918′W, 503 m water depth)

SCIENCE UPDATE: A meeting was held to discuss the scientific results from Site U1381 and scientists continued working on reports. Interviews and the production of animations continued for the videos that will be produced. A third ship tour was given by the Operations Superintendent. At Hole U1380C, we continued trying to identify the extent of the problematic zone. The bit was raised with the top drive to 289 mbsf, the top drive was set back, and the bit was raised with the drill pipe to 37 mbsf. The drill pipe was run back into the hole to 337 mbsf and could not advance any further. The bit was raised again to 318 mbsf, the top drive was picked up, and the hole was washed and reamed to 438 mbsf, encountering 25 m of fill at the bottom. Two sweeps of mud were pumped into the hole and the process was repeated. The bit was raised to 318 mbsf, the top drive was set back, and the bit was raised further to 37 mbsf. The bit was run back into the hole to 347 mbsf and could not advance any further. The top drive was picked up and an attempt was made to jet in the 14¾ inch bit. The bit was eventually worked to 425 mbsf after encountering a tight zone at 366 mbsf. Having made the decision earlier in the day to cement the problematic zone, the rig was prepared for cementing. The bit was raised to 396 mbsf and the top drive was set back. Five barrels of water were pumped to clear the lines, followed by 65 barrels of cement slurry, and 10 barrels of water. The cement pump was switched back to the mud pump and an additional 47 barrels of water were pumped to displace any remaining cement. To ensure no cement was left in the drill string, the bit was raised to 299 mbsf, the cement line was flushed, and seawater was circulated at a high rate through the drill string at 2.5 times its capacity. The bit was raised further to 27 mbsf (inside the 16 inch casing), the cement line was flushed again, and seawater was circulated through the drill string at 3 times its capacity. At the end of the day we were waiting for the cement to set.