IODP Expedition 355
Arabian Sea Monsoon
Daily Science Report for 31 May 2015
Location: At Mumbai harbor anchorage
Science Update: We finalized all expedition reports and held a final science meeting in the morning during the final leg of the transit to the Mumbai pilot station. The pilot boarded the vessel at 1026 h on 31 May. At 1112 h we dropped anchor at in the Mumbai harbor anchorage, officially ending Expedition 355.
Daily Science Report for 30 May 2015
Location: Underway for Mumbai, India
Science Update: The scientists continued finalizing all expedition reports and making sure that all data were entered into the database. We also held a final science meeting to review the results of Site U1457. We are underway for Mumbai, with an estimated time of arrival at the pilot station of 1030 h on 31 May.
Daily Science Report for 29 May 2015
Location: Underway for Mumbai, India
Science Update: We continued to RCB core in Hole U1457C, cutting and recovering Core 98R to a total depth of 1108.6 m. We terminated drilling operations after retrieving Core 98R on deck as time allotted for the expedition drilling operations expired. We then began to pull out of the hole, with the bit clearing the seafloor at 1050 h. After slipping and cutting the drilling line, we continued to retrieve the drill string back to the vessel. The bit was back on the rig floor at 2115 h and the drill crew secured the rig for transit. After the thrusters were raised, we began our transit to Mumbai at 2300 h. Estimated time of arrival at the Mumbai pilot station is 0700 h on 31 May.
Cores 96R through 98R were split and described. The uppermost core consists of dark gray claystone and interbedded volcaniclastic deposits. Igneous rock interpreted as basement is found at the base of this core and continues to the total depth of the hole. The basalt contains clinopyroxene, plagioclase, and olivine phenocrysts. It is mostly nonvesicular with veins up to 3 mm in width. Three intervals are comprised of mostly volcanic glass. The limited amount of time remaining in the expedition precluded microscopic and geochemical analysis of these rocks, which will be conducted postcruise. The scientists began to finalize the Site U1457 reports.
Daily Science Report for 28 May 2015
Location: Hole U1457C (17°9.9486′N, 67°55.8121′E; water depth 3522.7 m)
Science Update: We continued to RCB core in Hole U1457C, cutting and recovering Cores U1457C-90R through 96R to 1099.4 m. The rate of penetration slowed significantly while cutting Core 96R (at ~1098 m) and upon retrieval we discovered mafic igneous rock in the core catcher. We then switched to cutting half-length cores to improve recovery in the igneous rock and Core 97R to 1104.0 m was recovered by the end of the day. The drill crew pumped 35-barrel high-viscosity mud sweeps every couple of cores and the hole remains in good condition. Core recovery was generally low (average 35%) in the sedimentary rock section overlying basement, but improved significantly in Core 97R (83%), which is composed of igneous rock. Cores U1457C-88R through 95R (1016.1–1085.0 m) were split and described. The upper part of this interval consists of gray calcarenite, greenish brown limestone, and carbonate breccia with clasts composed of whitish and pinkish limestone, claystone, and volcanic fragments. Calcareous nannofossil and foraminifer assemblages in this interval are a mix of Paleogene and early Neogene species. The lower part of the described interval consists of dark brown massive claystone overlying dark greenish gray silty claystone that contains carbonate-cemented nodules. Calcareous nannofossil and planktonic foraminifer biostratigraphy indicate that this interval is Paleogene in age.
Daily Science Report for 27 May 2015
Location: Hole U1457C (17°9.9486′N, 67°55.8121′E; water depth 3522.7 m)
Science Update: We continued to RCB core in Hole U1457C, cutting and recovering Cores U1457C-87R through 89R to 1034.3 m. The rate of penetration remained low throughout the day. The drill crew pumped one 35-barrel high-viscosity mud sweep and the hole remains in good condition. Core recovery was very poor in Core 87R (5%), but improved significantly in Cores 88R (106%) and 89R (82%). Cores U1457C-82R through 87R (967.6–1011.36 m) were split and described. Most of this interval consists of dark greenish gray claystone interbedded with bluish silty claystone and gray silty claystone with nannofossils. Titled bedding, folds, and slickensides are common over this interval, although there are discrete sections where bedding is horizontal. The base of the interval is very indurated gray calcilutite. Calcareous nannofossil biostratigraphy indicates that the claystone is late Miocene in age. The calcilutite contains a mixed assemblage of Paleogene to early Neogene taxa.
Daily Science Report for 26 May 2015
Location: Hole U1457C (17°9.9486′N, 67°55.8121′E; water depth 3522.7 m)
Science Update: We continued to RCB core in Hole U1457C, cutting and recovering Cores U1457C-78R through 86R to 1011.1 m. The rate of penetration decreased dramatically at ~1004 m while cutting Core 85R. The drill crew pumped 35-barrel high-viscosity mud sweeps every few cores and the hole remains in good condition. Core recovery was very good over Cores 78R through 84R (89%), but then decreased to 35% and 63% in Cores 85R and 86R, respectively. Cores U1457C-73R through 81R were split and described. This interval is dominantly light greenish gray to dark gray claystone with lesser amounts of light bluish to brownish silty claystone and silty claystone with nannofossils. Bedding is chaotic, with tilted beds and intervals with near-vertical bedding; small faults, folds, and slickensides are also observed. Calcareous nannofossil biostratigraphy indicates that this interval is late Miocene in age, although reworking of Paleogene to early Miocene species is prevalent.
Daily Science Report for 25 May 2015
Location: Hole U1457C (17°9.9486′N, 67°55.8121′E; water depth 3522.7 m)
Science Update: We continued to RCB core in Hole U1457C, cutting and recovery Cores U1457-68R through 77R to 928.8 m. The drill crew pumped 30-barrel high-viscosity mud sweeps every few cores and the hole remains in good condition. Core recovery improved significantly over this interval, averaging 93%. In the laboratories, Cores U1457C-65R through 72R were split and described. The upper part of the interval consists of sets of dark gray sandstone grading into sandy siltstone and light brownish gray silty claystone. The sandstone beds have sharp, erosive lower contacts and are rich in mica. A short interval of light greenish nannofossil-rich claystone and white nannofossil chalk separates the coarser material above from dark green claystone below. The nannofossil-rich interval is heavily bioturbated with Zoophycos and Planolites burrows. The dark green claystone includes thin beds of sandstone and siltstone, as well as some nannofossil-rich intervals. Tilted bedding becomes more common towards the base of the described section. Calcareous nannofossil and planktonic foraminifer biostratigraphy indicate that these rocks are late Miocene in age.
Daily Science Report for 24 May 2015
Location: Hole U1457C (17°9.9486′N, 67°55.8121′E; water depth 3522.7 m)
Science Update: We continued to RCB core in Hole U1457C, cutting and recovering Cores U1457C-56R through 67R to 831.8 m (38% recovery). The drill crew pumped 30-barrel high-viscosity mud sweeps every few cores and the hole remains in good condition. Cores U1457C-49R through 64R were split and described. The uppermost part of the described interval is dominantly light gray to white nannofossil chalk and dark greenish gray nannofossil-rich claystone. The chalk is more heavily bioturbated than the claystone, with common Chondrites, Zoophycos, and Planolites burrows. Downcore, the section becomes dominantly silty claystone, sandy siltstone, and silty sandstone. The bases of the coarser grained beds are sharp and erosive, and these beds grade upward into finer grained lithologies. Wood fragments and pyrite nodules occur throughout this interval. Calcareous nannofossil and planktonic foraminifer biostratigraphy date these rocks to the late Miocene.
Daily Science Report for 23 May 2015
Location: Hole U1457C (17°9.9486′N, 67°55.8121′E; water depth 3522.7 m)
Science Update: We continued to RCB core in Hole U1457C, cutting and recovering Cores U1457C-44R through 55R to 715.4 m. The drill crew pumped 30-barrel high-viscosity mud sweeps every few cores and the hole remains in good condition. Core recovery was generally good over much of this interval (57%), with five cores recovering >70%. In the laboratories, Cores U1457C-39R through 48R were split and described. The upper part of this interval consists of cycles of sediment, with silty sandstone or sandy siltstone at the base, which grades upward into silty claystone. The sandstone or siltstone that comprise the base of each cycle is sharp-based and erosive. Wood fragments and pyrite occur throughout. The lower part of this interval consists of light gray to greenish gray nannofossil chalk and nannofossil-rich claystone. These rocks are moderately to heavily bioturbated, with Zoophycos, Planolites, Chondrites, and Skolithos burrows. Calcareous nannofossil and planktonic foraminifer biostratigraphy date these rocks to the late Miocene.
Daily Science Report for 22 May 2015
Location: Hole U1457C (17°9.9486′N, 67°55.8121′E; water depth 3522.7 m)
Science Update: We cut and recovered Cores U1457C-31R through 43R (472.9–599.0 m). The drill crew pumped 30-barrel high-viscosity mud sweeps every few cores and the hole remains in good condition. Core recovery averaged 40%. Cores U1457C-25R through 38R (414.70–544.71 m) were split and described. The uppermost part of this interval is dominantly dark gray nannofossil-rich claystone with interbedded whitish gray nannofossil chalk, which are heavily bioturbated with common Zoophycos, Chondrites, and Planolites burrows. Below the carbonate-rich interval are interbeds of clayey siltstone that grade upward into silty claystone. Coarser grained material becomes more abundant down-section, with silty sand/sandstone at the base of the graded intervals. There is a return to nannofossil-rich claystone and nannofossil chalk at the base of the described interval. Calcareous nannofossil and planktonic foraminifer biostratigraphy indicate that this interval is late Miocene to early Pleistocene in age.
Daily Science Report for 21 May 2015
Location: Hole U1457C (Final: 17°9.9486′N, 67°55.8121′E; water depth 3522.7 m)
Science Update: We continued to RCB core in Hole U1457C, cutting and recovering Cores U1457C-17R through 30R to 472.9 m. The drill crew pumped 30-barrel high-viscosity mud sweeps every few cores and the hole remains in good condition. Core recovery was extremely variable over the cored interval, ranging from 1% to 102% (average 41%). In the laboratories, Cores U1457C-14R through 24R (308.0–413.47 m) were split and described. The upper portion of this interval was poorly recovered and consists of interbedded brownish gray silty clay and sandy silt that fine upward. The sandy silt beds have sharp bases and grade upward to massive silty clay. The sediments become more indurated in Core 18R and consist mostly of silty claystone and clayey siltstone with small amounts of silty sand. As with the clay and silt above, the sharp-based siltstone grades upward into claystone. Carbonate content increases at the base of the described interval, with the cores dominated by nannofossil-rich claystone and nannofossil chalk. These rocks are strongly bioturbated with common Zoophycos and Chondrites traces. Pyrite occurs throughout. Calcareous nannofossil and planktonic foraminifer biostratigraphy indicate that the base of this interval is early Pleistocene in age. CHNS analysis was completed for Holes U1457A and U1457B and the results show a distinct change at ~70 mbsf, with higher calcium carbonate and total organic carbon content above that depth.
Daily Science Report for 20 May 2015
Location: Hole U1457C (Preliminary: 17°9.9′N, 67°55.7′E; water depth 3522.7 m)
Science Update: We finished drilling ahead without coring at 191.6 m and then recovered the wash barrel. We began RCB coring and by the end of the day had cut and recovered Cores U1457C-2R through 16R (191.6–337.1 m). Core recovery was poor over this interval, ranging from ~0.5% to 38% (average 11%). Cores U1457B-29F through 33F (181.20–205.20 m) were split and described. The upper part of this interval consists of light brownish silty clay and sandy silt. The bases of the sandy silt beds are erosive, and the silt grades upward into silty clay. The silty clay is mottled and massive, indicating heavy bioturbation. The base of Hole U1457B is predominantly light brownish gray silty sand, interbedded with thin beds of silty clay. Calcareous nannofossil and planktonic foraminiferal biostratigraphy indicates that the base of Hole U1457B is early Pleistocene in age. We also split and described Cores U1457C-2R through 13R (191.60–298.66 mbsf). This interval is comprised of dark gray silty clay and sandy silt. The bases of the sandy silt beds are typically erosive and the beds grade upward into silty clay. Calcareous nannofossils are generally common throughout this interval, whereas planktonic foraminifer are sometimes common, but also absent in some horizons. Biostratigraphy indicates that this interval is early Pleistocene in age.
Daily Science Report for 19 May 2015
Location: Hole U1457C (Preliminary: 17°9.9′N, 67°55.7′E; water depth 3522.7 m)
Science Update: Today, we continued recovering the drill string. A short interruption in this occurred when a hydraulic hose on the pipe racker failed when the bit was at 2108.0 mbrf. After repairs were made, we continued to retrieve the drill string to the ship, with the bit clearing the rig floor at 0810 h, ending Hole U1457B and beginning Hole U1457C. We offset the ship 15 m east of Hole U1457A, prepared the RCB coring bottom-hole assembly, and began to lower the bit toward the seafloor. When the bit reached 199.0 mbrf, we stopped temporarily to another part of the pipe racker. We then continued lowering the pipe toward the seafloor, reaching 3509.6 mbrf. We picked up the top drive, deployed a wash barrel, and started Hole U1457C at 1830 h. We had drilled without coring to 191.6 m by the end of the day.
Cores U1457B-21F through 27F (143.6–176.5 m) were split and described. This interval consists primarily of brownish silty clay and dark gray sandy silt. The bases of the sandy silt beds are erosive, and the silt grades upward into silty clay. Calcareous microfossils are rare to few in abundance in this interval and indicate an early Pleistocene age. Analysis of carbonate content from Hole U1457A indicates that carbonate content is generally low (<20 wt%), with a few intervals of much higher carbonate (>70 wt%) that correspond to calcareous ooze. Stratigraphic correlation between Holes U1457A and U1457B indicates that we recovered a continuous section down to ~90 m.
Daily Science Report for 18 May 2015
Location: Hole U1457B (Final: 17°9.9485′N, 67°55.7955′E; water depth 3523.6 m)
Science Update: We collected Cores U1457B-3H through 13H to 110.7 m, with one 3 m interval advanced without coring (88.7–91.7 m) for stratigraphic correlation purposes. After having to pump out the core liners for Cores 10H and 12H, we switched to the half-length APC system and collected Cores U1457B-14F and 15F to 120.1 m. We then began alternating between 4.7 m long HLAPC cored intervals and 4.8 m drilled intervals to accelerate depth penetration. Cores 17F through 33F were collected to 204.7 m, where we terminated the hole. We then pulled out of the hole, clearing the seafloor at 2250 h, and continued raising the pipe toward the ship to switch to the RCB coring system for Hole U1457C.
Cores U1457A-6H through 19F (46.7–144.8 m) were split and described. Cores 6H through 8H are comprised of light greenish to light gray nannofossil ooze, gray nannofossil-rich clay, and whitish calcareous ooze, with interbeds of silty clay and silty sand. The silt and sand beds have erosive bases. Burrowing is common in the carbonate-rich lithologies. Cores 9H through 19F are composed of brownish gray silty clay with thin interbeds of sandy silt. A distinct change in physical properties occurs at this change in lithology and is similar to that seen in the upper part of the stratigraphy at Site U1456. Calcareous nannofossil biostratigraphy indicates that the base of Hole U1457A is early Pleistocene in age. In Hole U1457B, Cores U1457B-1H through 3H (0–22.2 m) were also split and described. These cores are dominated by nannofossil ooze and calcareous ooze, with minor interbeds of sandy silt or clayey silt. The uppermost portion of the first core also contains a rich assemblage of siliceous microfossils. Calcareous nannofossil and planktonic foraminifer biostratigraphy indicates a Middle to Late Pleistocene age for these cores. The scientists also held a final science meeting for Site U1456.
Daily Science Report for 17 May 2015
Location: Hole U1457B (Preliminary: 17°9.94′N, 67°55.80′E; water depth 3523.6 m)
Science Update: After the first attempt at starting Hole U1457A retrieved a water core, we positioned the bit 3 m deeper (3524.0 mbrf) but again recovered a water core. For the third attempt we lowered the bit to 3533.5 mbrf and successfully started Hole U1457A at 0045 h, establishing a seafloor depth of 3534.3 mbrf. We recovered Cores U1457A-1H through 12H to 111.2 m, collecting APCT-3 temperature measurements on Cores 4H, 7H, and 10H. After Core 12H came back with a shattered liner, we switched to the half-length APC and began alternating between cored intervals and 4.8 m drilled intervals to accelerate depth penetration. Cores 13F, 15F, 17F, and 19F were collected to 144.8 m, where we terminated the hole. We then pulled out of the hole, clearing the seafloor at 2015 h, ending Hole U1457A. We offset the vessel 15 m west, positioned the bit at 3528.5 mbrf, and started Hole U1457B at 2140 h, recovering 3.22 m of sediment. At the end of the day we had collected Core U1457B-2H to 12.7 m.
Cores U1457A-1H through 5H were split and described. Light greenish to light gray nannofossil ooze and light gray nannofossil-rich clay are the dominant lithologies over much of this interval. Thin layers of silty sand or sandy silt with erosive bases are seen throughout the section and grade upward to finer lithologies. Burrowing is common, particularly in the nannofossil-rich clay and nannofossil ooze. Calcareous nannofossil and foraminifer biostratigraphy, together with magnetostratigraphy, indicate that the base of Core 5H is Early Pleistocene in age. We see a transition in Core 9H from variable magnetic susceptibility above to very low values below. We also held a ship-to-shore event with high school students in Kathmandu, Nepal.
Daily Science Report for 16 May 2015
Location: Hole U1457A (Preliminary: 17°9.94′N, 67°55.80′E; water depth 3522.6 m)
Science Update: We continued to pull the drill string back to the ship, clearing the rotary table at 0755 h. After preparing the rig floor for transit, we raised the thrusters and began sea passage to Site U1457 (alternate proposed Site IND-06B), arriving on site at 1330 h. We made up the APC/XCB bottom-hole assembly and began to lower the drill string toward the seafloor. We positioned the bit at 3521 mbrf and shot the first core, which came up full of water. At the end of the day we had lowered the bit 3 m in a second attempt to start Hole U1457A. The scientists continued to work on finalizing the Site U1456 reports. Two scientists presented results from the seawater samples that were taken at Site U1456 to examine living plankton assemblages at that location to compare to the assemblages preserved at the seafloor.
Daily Science Report for 15 May 2015
Location: Hole U1456E (16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We continued to run in the hole with the drill string and planned to wash and ream back to the total depth of 1109.4 m and resume RCB coring. However, the bit encountered an obstruction within the casing at 725.6 m. We raised the bit back up to 706.2 m, picked up the top drive, and deployed a wash barrel. We were able to wash past the obstruction and continued lowering the bit to 822.7 m, below the end of the casing. We then washed and reamed the hole to 920.0 m. We experienced excessive torque and pump pressures from 890–920 mbsf. We continued reaming to 936 mbsf with no improvement in hole conditions and the drill string became stuck several times. After very little progress in advancing the bit deeper over a 12 h period and the increasing danger of getting stuck, we decided to abandon Hole U1456E. The bit cleared the seafloor before midnight. We decided to spend our remaining time at alternate proposed Site IND-06B, which provides the opportunity to address the basement objectives of the expedition. The scientists began to work on finalizing the Site U1456 reports. We also held a ship-to-shore event with elementary school students in Bronx, New York (USA).
Daily Science Report for 14 May 2015
Location: Hole U1456E (16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We continued trying to reenter Hole U1456E throughout much of the day. Part of this time was spent waiting for particles in the water column to settle back to the seafloor. We visually identified the reentry cone twice, but were unsuccessful in maneuvering the ship for reentry. After losing communication with the camera, we retrieved it to the ship, fixed the problem, and redeployed the camera. We successfully reentered Hole U1456E at 2100 h, lowered the drill string to 68.0 mbsf, and retrieved the subsea camera, before continuing to lower the pipe into the hole. The scientists continued to revise site report drafts. We also held four ship-to-shore events throughout the day. The Virginia Museum of Natural History (USA) organized three, two with middle and high school students and one with an adult audience at a “science café” evening at the museum. We also connected with elementary school children in Italy.
Daily Science Report for 13 May 2015
Location: Hole U1456E (16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We continued to trip the drill string up to the ship, with the bit clearing the rotary table at 0740 h. We made up a bottom-hole assembly with a new mechanical bit release and new RCB coring bit and then began to run the drill string back toward the seafloor. We deployed the subsea camera at 1505 h. The subsea camera was near the seafloor and ready for reentry operations at 1900 h. We made two unsuccessful attempts to reenter Hole U1456E by the end of the day. Reentry is hampered by significant amounts of white drilling mud that is causing backscatter of light. The scientists worked on revisions of the Site U1456 reports and submitted revised Methods sections. We also held a ship-to-shore video event with children aged 6–10 at the Virginia Museum of Natural History, USA.
Daily Science Report for 12 May 2015
Location: Hole U1456E (16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We cut and recovered Cores U1456E-16R through 19R to 1109.4 m, pumping a 40-barrel high-viscosity mud sweep after every core. Penetration rates started to increase (from ~3.5 to ~7 m/h) while cutting Core 18R. We then began to trip out of the hole for a bit change. The drill string cleared the seafloor at 2330 h and at the end of the day the bit was at 3626.3 mbrf. Core recovery was very good in Cores 16R and 17R (90%) and decreased in Cores 18R and 19R (45%). Cores U1456E-14R through 19R were split and described. The upper part of this interval is dominated by breccia, with lesser amounts of multicolored claystone. Breccia clasts are up to 8 cm and composed of limestone, claystone, and volcanic fragments. Light gray calcarenite and limestone are abundant downhole and the limestone is heavily bioturbated. Much of this interval contains a mix of Paleogene to early Miocene nannofossils and foraminifers. A distinct change in lithology to calcareous-rich sandstone, claystone, and silty claystone occurs in Core 19R. Scarce nannofossils in this core indicate a Miocene age for the sandstone and claystone. We also listened to a science presentation about variations in the oxygen minimum zone in the Arabian Sea through the Pleistocene.
Daily Science Report for 11 May 2015
Location: Hole U1456E (16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We cut and recovered Cores U1456E-10R through 15R (1026.3–1072.9 m), pumping a 30-barrel high-viscosity mud sweep after every core. Core recovery was reasonably good in Cores 10R and 11R (76%), but decreased significantly in Cores 12R–14R (28%). Core 15R recovered 248%, which probably included some material from the previous cored interval that had been left in the hole. At the end of the day we were cutting Core 16R. Cores U1456E-8R through 13R were split and described. This interval consists of gray conglomerate, light gray to light greenish white limestone and nannofossil chalk, light gray calcilutite, and multi-colored silty claystone. Clasts in the conglomerate range in size from a few millimeters to more than 10 cm and consist of limestone, claystone, and volcanic fragments. Rare gastropods are found in the limestone. Calcareous nannofossil and planktonic foraminifer biostratigraphy shows a mix of Paleogene to early Miocene assemblages over this interval. We also conducted two ship-to-shore events, one with an elementary school in Birmingham, UK, and the other with an elementary school in New York, USA.
Daily Science Report for 10 May 2015
Location: Hole U1456E (16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We cut and recovered Cores U1456E-4R through 9R (976.6–1026.3 m), pumping a 30-barrel high-viscosity mud sweep after every core. At the end of the day, Core 10R had been cut to 1027.5 m. Core recovery over this interval was 61%. Cores U1456E-3R through 7R were split and described. Light greenish to white calcarenite dominates the upper part of this interval, with lesser amounts of calcilutite and claystone. Burrowing is common in the claystone intervals. Below this, the cores consist of a mix of claystone, limestone, and conglomerate or breccia. Clasts in the conglomerate/breccia are up to 5 cm in size and are composed of claystone, limestone, and basalt. Based on calcareous nannofossil and foraminifer biostratigraphy, this interval consists of a mix of Paleogene to early Miocene assemblages.
Daily Science Report for 9 May 2015
Location: Hole U1456E (16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We continued drilling ahead in Hole U1456E to 970.0 m and pumped a 40-barrel high-viscosity mud sweep. After retrieving the center bit, we found 4 m of fill in hole, so we deployed a wash barrel and washed through the loose fill, circulating two 50-barrel high-viscosity mud sweeps to stabilize the hole. We recovered the wash barrel and then deployed a core barrel. Core U1456E-3R was cut to 976.6 m, recovering 7.5 m of core. At the end of the day, Core U1456E-4R had been cut to 978.0 m. The scientists spent the day revising Site U1456 report drafts and preparing for the renewed arrival of core. Core U1456E-3R was run on the Special Task Multisensor Logger (STMSL) after it was curated, and stratigraphic correlation suggests that it correlates to Core U1456D-56R.
Daily Science Report for 8 May 2015
Location: Hole U1456E (16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We continued lowering the RCB bit to near the seafloor and then deployed the subsea camera. We reentered Hole U1456E at 0306 h and retrieved the subsea camera back to the ship. We lowered the bit until it reached 706.1 m and then picked up the top drive. After deploying the center bit, we tagged bottom at 748.2 m, encountering no fill. After pumping a mud sweep, we began to drill ahead, pumping a 30-barrel high-viscosity mud sweep after every third connection. By the end of the day we had reached to 854.9 m, with a rate of penetration of 9.5 m/h. The scientists submitted drafts of their Site U1456 reports. Two scientists gave science talks. The first covered the evolution of the Asian Monsoon during the late Cenozoic based on dust records from China. The second presented geochemical results from igneous outcrops in India related to the Marion and Reunion Plumes. We also held a ship-to-shore event with researchers and graduate students at the National Institute of Oceanography in India.
Daily Science Report for 7 May 2015
Location: Hole U1456E (16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We continued to drill in the reentry cone and 10¾″ casing string to a final depth of 734.4 m, landing the reentry cone on the seafloor at 0105 h. We released the casing running tool and pulled the underreamer and mud motor drilling assembly into the casing with no problems. After tripping the drilling assembly to 411.6 mbsf, we retrieved the subsea camera back to the drill ship, and then continued the trip out of the hole. The drilling assembly cleared the rig floor at 1415 h. After removing the casing drilling assembly, we made up the RCB bottom-hole assembly and began lowering the pipe back toward the seafloor. By the end of the day, the bit was at 2809.8 mbrf. The scientists continued to work on revising the Site U1456 reports to include the results from Hole U1456D. We also held three ship-to-shore events: one with the Ministry of Earth Sciences (MOES) in India, and two with high school students taking marine science at Woodrow Wilson High School in Washington, DC (USA).
Daily Science Report for 6 May 2015
Location: Hole U1456E (Final: 16°37.2857′N, 68°50.3541′E; water depth 3637 m)
Science Update: We continued to drill in the reentry cone and 10¾″ casing string with the mud motor and underreamer assembly throughout the day, reaching 734.9 m by midnight. We held a Site U1456 science meeting, with each laboratory group presenting the results from Holes U1456C and U1456D. The scientists also continued to write up the results from Hole U1456D. We collected seawater samples from the surface and 5 m, 10 m, and 15 m water depth for analysis of plankton assemblages by the micropaleontologists. These results will be compared to assemblages preserved in mudline samples.
Daily Science Report for 5 May 2015
Location: Hole U1456E (Preliminary: 16°37.29′N, 68°50.35′E; water depth 3637 m)
Science Update: We finished making up the ~744 m string of casing and deployed the drilling assembly with the tri-cone bit, mud motor, and underreamer through the casing. We latched the casing running tool into the reentry cone and deployed the entire reentry cone/casing with drilling assembly at 0350 h. As we lowered it toward the seafloor, we filled the drill pipe with seawater every 15 stands. During the pipe trip, we deployed the subsea camera and lowered it to just above the reentry cone. After slipping and cutting the drill line, we started drilling the casing into the seafloor (Hole U1456E) at 2130 h. By the end of the day, the casing string had reached to 94.4 m. In the laboratories, the biostratigraphers and paleomagnetists developed a preliminary age model for Hole U1456D. All of the scientists continued to prepare presentations for the science review meeting scheduled for Wednesday.
Daily Science Report for 4 May 2015
Location: Hole U1456E (Preliminary: 16°37.2′N, 68°50.3′E; water depth 3637 m)
Science Update: We finished picking up the drill collars and then began to make up the drilling assembly to run the casing, which includes a mud motor, tri-cone bit, and underreamer with arms set to open to 12¾″. After testing the mud motor and underreamer functionality, this assembly was moved to the pipe racker. We then positioned the reentry cone over the moonpool doors and latched into it with the casing running tool. We began to make up the 10¾″ casing string, welding the first five casing joints together. The total length of the casing to be deployed is 744 m. We ended the day by latching the 10¾″ casing hanger into the reentry cone. The scientists continued to work on writing up results from Hole U1456D and preparing presentations for the upcoming science meeting. Scientists attended a talk about biomarker results from IODP Expedition 318 (Wilkes Land Margin) that indicate that the early Eocene Antarctic was warm enough to support palm trees.
Daily Science Report for 3 May 2015
Location: Hole U1456E (Preliminary: 16°37.2′N, 68°50.3′E; water depth 3637 m)
Science Update: The pipe severing tool was retrieved to the rig floor at 0045 h. We then continued to pull out of the hole with the drill pipe, with the bottom of the severed drill string clearing the seafloor at 0425 h. Upon inspection at the rig floor, we discovered that the 5″ drill pipe that had been near the seafloor was bent, explaining why the core barrel was unable to pass that point. The bent 5″ drill pipe joints were removed from service. The end of the pipe cleared the rig floor at 2200 h, ending Hole U1456D. Since we did not achieve our deep objectives at Hole U1456D, we decided to install a new reentry cone with ~750 m of casing in Hole U1456E, drill down to ~1024 m, and then core and log below that depth. At the end of the day, we started picking up drill collars to make up the drilling assembly for the Hole U1456E casing operations. The scientists began working on writing up the results from Hole U1456D and preparing to present those results at a science meeting later in the week. We also listened to a talk on applications of multibeam bathymetry.
Daily Science Report for 2 May 2015
Location: Hole U1456D (16°37.2766′N, 68°50.3365′E; water depth 3637.2 m)
Science Update: We continued to lower the new bit into Hole U1456D, encountering fill at 995.8 mbsf. We picked up the top drive, but were unable to rotate the drill string or circulate drilling fluid. We were able to pull the bit up to 937.5 m before encountering overpull. We then began to work the drill string and re-established circulation; however, we were unable to free the drill string. We dropped a core barrel through the drill string to see if we could determine the location of the problem but it was unable to pass below 3668 mbrf (just below the seafloor). We deployed the subsea camera and could not observe the reentry cone, which appeared to be buried in cuttings. Since the drill string extended straight upward from the cuttings pile there was no discernable evidence why the core barrel should not pass that point. After retrieving the subsea camera to the ship, we prepared for pipe severing operations. The severing tool was deployed at 1800 h and had no trouble passing the point where the core barrel would not pass. The tool was lowered to the bit and then raised to discharge in the first joint of 5½″ transition pipe above the drill collars. The charge fired at 2215 h, freeing the pipe. We retrieved the severing tools to the rig floor and then began to trip out of the hole. In the laboratories, most measurements for Hole U1456D are now complete and the scientists have begun writing up results from this hole. We also held a ship-to-shore event with the Lyme Regis Fossil Festival in the UK.
Daily Science Report for 1 May 2015
Location: Hole U1456D (16°37.2766′N, 68°50.3365′E; water depth 3637.2 m)
Science Update: We continued to trip the pipe out of the hole, with the bit reaching the rig floor at 0355 h. We changed out the bit and then began to trip back down toward the seafloor. We deployed the subsea camera and reentered Hole U1456D at 1515 h after 35 min of maneuvering the vessel. The drill crew replaced the WKM valve in the top drive while deploying and retrieving the subsea camera. After reentry, we continued tripping into the hole, but encountered an obstruction at 442.5 m, still inside of the casing. After picking up the top drive, we were able to wash through the obstruction. After racking back the top drive, we continued the trip into the hole, reaching 704.5 m by the end of the day. In the laboratories, scientists continued analysis of discrete samples for paleomagnetics, moisture and density, and CHNS analysis. We also listened to a talk on X-ray fluorescence (XRF) core scanning and its application to equatorial Pacific cores.