IODP Expedition 362
Sumatra Seismogenic Zone
Daily Science Report for 5 October 2016
Location: In transit to Singapore
Science Update: We finalized the Site U1481 reports and Expedition Summary. A short meeting was held to highlight the key findings of Expedition 362.
The JOIDES Resolution completed 242 nmi (979 nmi total) of the 1039 nmi transit at a speed of 10.1 kt (11.2 kt average). The vessel arrived at the Loyang Offshore Terminal in Singapore at 0845 h on 6 October.
Daily Science Report for 4 October 2016
Location: In transit to Singapore
Science Update: The JOIDES Resolution completed 282 nmi (737 nmi total) of the 1039 nmi transit at a speed of 11.8 kt.
We continued working on Site U1481 reports and the Expedition Summary (Preliminary Report), finalized data archiving, and cleaned the laboratories for the next expedition.
Daily Science Report for 3 October 2016
Location: In transit to Singapore
Science Update: The JOIDES Resolution completed 297 nmi (455 nmi total) of the 1039 nmi transit to Singapore at a speed of 12.4 kt.
We held a science meeting to review the downhole logging and core-log-seismic integration results for Site U1481, and continued working on reports.
Daily Science Report for 2 October 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A); in transit to Singapore
Science Update: The crew continued pulling the drill string to the surface, and the end of the pipe reached the rig floor at 0540 h. After several failed attempts to release the beacon, it was left on the seafloor. The thrusters were raised at 0830 h and the JOIDES Resolution departed Site U1481 for the transit to Singapore. At the beginning of the transit, we collected a roughly south to north magnetic profile between Sites U1481 and U1480, and recovered the magnetometer at 1548 h. The vessel completed 158 nmi of the 1039 nmi transit at a speed of 10.2 kt.
We held the Site U1481 science review meeting and the scientists continued working on their reports.
Daily Science Report for 1 October 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: In preparation for logging, 350 barrels of heavy mud were pumped in the hole and the end of the drill string was raised to a logging depth of 61 mbsf (~4251 mbrf). Given the concern that the hole might not stay open long enough, we decided to log with a single, modified triple combo tool string that included the spectral gamma ray, caliper, sonic, resistivity, and magnetic susceptibility tools. The tools were rigged up by 0845 h and were lowered first into the casing and then into the open hole, where they encountered no resistance all the way to the bottom of the hole. Data were collected from 1494 mbsf to the seafloor, and the logging tools were back at the surface by 1940 h and rigged down by 2100 h. The crew started to pull the drill string to the surface, and at midnight the end of the drill pipe was at 2469 mbrf. The vessel is scheduled to depart Site U1481 tomorrow morning for the transit to Singapore.
All cores from Hole U1481A have been measured on the whole-round and section-half loggers, described, and sampled for shipboard and postcruise analyses. Measurements are in progress for the final interstitial water, moisture and density, and discrete paleomagnetic samples.
Cores U1481A-37R to 38R consist of greenish gray or reddish black clay with agglutinated foraminifers. Minor lithologies include convolute and planar laminated laminae of silt and clay and normally graded, partially carbonate-cemented, very fine sandstone and siltstone with convolute and planar lamination. Bedding dips remain subhorizontal.
Scientists worked on the Site U1481 reports.
Daily Science Report for 30 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: Cores U1481A-34R to 38R advanced from 1451.1 to 1500.0 mbsf with 43.3 m recovered (89%). Coring was terminated and the drill bit was released at 2315 h in preparation for downhole logging.
All cores through Core U1481A-37R have been measured on the whole-round loggers. All cores through Core 36R have been measured on the section-half loggers, described, and sampled for shipboard and postcruise analyses. Moisture and density measurements are completed through Core 30R.
Cores U1481A-32R to 36R consist of very dark gray and dark reddish brown clay with silt. The lower part of Core 36R contains medium to thick beds of fine sand/sandstone that contain plant fragments and rip up clasts. Bedding dips remain subhorizontal.
Daily Science Report for 29 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: Cores U1481A-29R to 34R advanced from 1402.5 to 1451.1 mbsf with 47.2 m recovered (97%). Although hole conditions remain excellent, coring will end tomorrow to allow sufficient time for logging.
All cores through Core U1481A-32R have been measured on the whole-round loggers. All cores through Core 31R have been measured on the section-half loggers, described, and sampled for shipboard and postcruise analyses. Moisture and density measurements are completed through Core 25R.
Cores U1481A-26R to 31R are dominated by bioturbated, dark green and reddish brown clay with silt laminae. Starting with Core 31R, the lithology consists of reddish brown clay with occasional greenish gray silty clay and thin beds of intercalated ash layers. Bedding dips remain subhorizontal.
Daily Science Report for 28 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: Cores U1481A-22R to 28R advanced from 1344.3 to 1402.5 mbsf with 49.0 m recovered (84%). Hole conditions continue to be good.
All cores through Core U1481A-26R have been measured on the whole-round loggers. All cores through Core 25R have been measured on the section-half loggers, described, and sampled for shipboard and postcruise analyses. Moisture and density measurements are completed through Core 18R.
Cores U1481A-19R to 25R consist of bioturbated, black to very dark gray, normally graded, silty clay/stone to claystone with variable amounts of calcareous components. The minor lithology consists of normally graded, medium to very fine sand with rip-up clasts and plant material. Below Core 23R, the lithology is dominated by slightly bioturbated, dark green and reddish brown claystone. Bedding dips remain subhorizontal.
Daily Science Report for 27 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: Cores U1481A-14R to 21R advanced from 1266.4 to 1344.3 mbsf with 35.1 m recovered (45%). Hole conditions are good.
All cores through Core U1481A-20R have been measured on the whole-round loggers. All cores through Core 18R have been measured on the section-half loggers, described, and sampled for shipboard and postcruise analyses. Moisture and density measurements are completed through Core 10R.
Cores U1481A-12R to 18R consist of slightly bioturbated, laminated, dark gray clay with silt. The minor lithology consists of normally graded, dark gray, medium to thick beds of fine sand with reworked clay clasts and wood fragments. Bedding dips remain subhorizontal and are affected locally by slump folding. Small-scale synsedimentary normal faults are also observed.
Daily Science Report for 26 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: Cores U1481A-5R to 13R advanced from 1178.9 to 1266.4 mbsf with 26.2 m recovered (30%). Hole conditions are good.
All cores through Core U1481A-12R have been measured on the whole-round loggers. All cores through Core 11R have been measured on the section-half loggers, described, and sampled for shipboard and postcruise analyses.
Cores U1481A-3R to 11R contain bioturbated, gray to very dark gray, very thin to thin beds of (calcareous) claystone alternating with laminae of parallel-laminated siltstone. These sediments are intercalated with greenish black, thin to medium bedded, normally graded fine to very fine sandstone layers that contain reworked and rounded claystone clasts as well as rare to common amounts of plant debris. Bedding dips remain subhorizontal and are affected locally by slump folding. The sediment is of late Miocene age.
Daily Science Report for 25 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: Drilling without coring continued from 1052.5 to 1149.7 mbsf. Coring started with the rotary core barrel (RCB) system at 1300 h. Cores U1481A-2R to 4R advanced from 1149.7 to 1178.9 mbsf with 18.98 m recovered (65%).
Cores U1481A-2R to 3R were measured on the whole-round loggers. Core 2R was measured on the section-half loggers, described, and sampled for shipboard and postcruise analyses.
The upper part of Core U1481A-2R consists of silty claystone with intercalated, normally graded beds of fine to very fine sandstone. The lower part consists of alternating silty clay and claystone. Bedding is horizontal and observed slump folds are consistent with what was found at Site U1480. The sediment is of late Miocene age.
Daily Science Report for 24 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: Drilling without coring continued in Hole U1481A from 858.2 to 1052.5 mbsf. The center bit was retrieved and inspected twice, and a small amount of sediment was recovered during the second inspection. Our goal is to start coring at 1150 mbsf.
Daily Science Report for 23 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: Hole U1481A was reentered at 0150 h and the subsea camera was brought back to the surface. The drill string was lowered into the casing until it encountered fill at 552.2 mbsf (~178 m above the bottom of the casing). The fill was cleaned out of the hole and then was swept with high-viscosity mud. Drilling ahead without coring below the casing continued for the rest of the day, with a break to retrieve and inspect the center bit. At midnight, the bit was at 858.2 mbsf, with our goal being to start coring at 1150 mbsf. We finished reviewing the Site U1480 reports and prepared the sampling plan for Hole U1481A.
Daily Science Report for 22 September 2016
Location: In transit to Site U1481;
Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: We completed the 989 nmi transit from Singapore at a speed of 10.6 kt. The JOIDES Resolution arrived at Site U1481 at 1100 h, the thrusters and hydrophones were lowered, and an acoustic seafloor-positioning beacon was deployed at 1242 h. A rotary core barrel (RCB) bottom-hole assembly was made up and the drill string was lowered to just above the seafloor. The subsea camera was deployed at 2100 h and lowered to the end of the drill string. At midnight, the vessel was maneuvering to reenter Hole U1481A.
Daily Science Report for 21 September 2016
Location: In transit to Site U1481
Science Update: Today we completed another 243 nmi of the 989 nmi transit at a speed of 10.1 kt. Our estimated time of arrival at Site U1481 is 1200 h on September 22. The plan upon arrival is to reenter Hole U1481A, drill without coring from 734 mbsf (the depth of the cased hole) to 1150 mbsf, and then RCB core to basement. We also reviewed Site U1480 reports and started planning postcruise publications.
Daily Science Report for 20 September 2016
Location: In transit to Site U1481
Science Update: The JOIDES Resolution completed 233 nmi (627 nmi total) of the 989 nmi transit at a speed of 9.7 kt. We reviewed Site U1480 reports and conducted an experiment with the Icefield and FlexIt orientation tools. IODP technical staff and Siem Offshore crew attended two talks on the science objectives of the expedition. After careful deliberation we have decided to return to Site U1481; our estimated time of arrival is 1200 h on September 22.
Daily Science Report for 19 September 2016
Location: In transit
Science Update: The JOIDES Resolution completed 281 nmi (394 nmi total) of the 989 nmi transit at a speed of 11.7 kt. We reviewed Site U1480 reports, and continued our discussion on whether to return to Site U1481 or move to Site SUMA-24A.
Daily Science Report for 18 September 2016
Location: In transit
Science Update: We departed from the Loyang Offshore Terminal in Singapore at 1206 h on September 18 to return to operations. We worked on Site U1480 report revisions, took additional samples for shore-based studies, and discussed whether to return to Site U1481 or proceed to Site SUMA-24A.
Daily Science Report for 17 September 2016
Location: Loyang Offshore Terminal, Singapore
Science Update: The crew completed the installation of the Elmagco brake. We continued reviewing the Site U1480 reports. Our departure is planned for 1200 h on September 18.
Daily Science Report for 16 September 2016
Location: Loyang Offshore Terminal, Singapore
Science Update: The crew continued to prepare the replacement Elmagco brake for installation and plan to test the brake before departure. We continued reviewing the Site U1480 reports, and took a few additional samples. Our estimated departure is at 1200 h on September 18.
Daily Science Report for 15 September 2016
Location: Loyang Offshore Terminal, Singapore
Science Update: The JOIDES Resolution continued the transit to Singapore to repair one of the drawworks brakes. The vessel completed the final 108 nmi of the 996 nmi transit at a speed of 9.4 kt, and docked at the Loyang Offshore Terminal at 1106 h. The aft Elmagco (eddy current) brake was taken off the vessel and transported to the Megawatts Engineering Services facility so that parts could be transferred to the replacement unit. The new brake arrived at the vessel in the evening and the crew started preparing it for installation. We continued reviewing the Site U1480 reports, and resampled some of the igneous basement cores for a shore-based request. Our estimated departure is at 1200 h on September 17.
Daily Science Report for 14 September 2016
Location: In transit to Singapore
Science Update: The JOIDES Resolution continued the transit to Singapore to repair one of the drawworks electric brakes. The vessel completed 300 nmi (888 nmi total) of the 996 nmi transit at a speed of 12.5 kt, and is expected to arrive at Singapore tomorrow morning. The Expedition Project Manager gave a presentation on postcruise information and publication obligations, and we started reviewing the submitted site reports.
Daily Science Report for 13 September 2016
Location: In transit to Singapore
Science Update: The JOIDES Resolution continued the transit to Singapore to repair one of the drawworks electric brakes. The vessel completed 284 nmi (588 nmi total) of the 996 nmi transit at a speed of 11.8 kt, and is expected to arrive at Singapore midday on September 15. The scientists submitted drafts of the Site U1480 reports and participated in a science seminar on the structure of the Sumatra margin. A few additional samples for postcruise research were taken from select cores.
Daily Science Report for 12 September 2016
Location: In transit to Singapore
Science Update: The JOIDES Resolution continued the transit to Singapore to repair one of the drawworks electric brakes. The vessel completed 271 of the 962 nmi transit at a speed of 11.8 kt. The scientists participated in a science seminar on radiolarians and continued to work on their reports. A few additional samples were taken from select cores.
Daily Science Report for 11 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A); in transit to Singapore or Malaysia
Science Update: Shortly after midnight it became apparent that one of the two drawworks eddy current brakes had failed. We continued raising the drill string and at 0630 h the casing running tool reached the surface. The mud motor, underreamer, and drill bit were disassembled by 1115 h, and it was noted that one of the underreamer cones was missing. While rig floor operations were going on, the crew verified that the large bearing needed to repair the brake is not available on board. Because the weight of the drill string is too much to operate with only one drawworks electric brake at the large water depth of Site U1481, operations had to be suspended. The rest of the day was spent trying to determine the extent of the damage and where the ship needed to go to make the repairs. At 2030 h we raised the thrusters and started heading toward the northern tip of Sumatra, with our most likely destination being Singapore or Port Klang, Malaysia.
The scientists participated in a science seminar on the paleoseismicity of the Hikurangi Margin and continued to work on their reports.
Daily Science Report for 10 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4178.3 m water depth; proposed Site SUMA-12A)
Science Update: We continued drilling in the reentry system, and the casing landed on the seafloor at 1910 h with the depth of the hole at 734.1 mbsf. The Hydraulic Release Tool (HRT) was released from the casing at 2000 h. The rest of the day was spent raising the drill string from the seafloor. The subsea camera was brought to the surface at 2300 h. The end of the drill string cleared the seafloor at 2225 h and was at 3830.3 m below the rig floor at midnight.
We held the Site U1480 science review meeting and scientists continued to work on their reports.
Daily Science Report for 9 September 2016
Location: Hole U1481A (2°45.2861′N, 91°45.5771′E, 4182.7 m water depth; proposed Site SUMA-12A)
Science Update: A mud motor, underreamer, and drill bit assembly was made up and run into the casing, and at 0530 h the stinger was attached to the top of the casing string with the Hydraulic Release Tool (HRT). The reentry system was lowered to the seafloor and reached 4180 m below rig floor at 1215 h. A free-fall funnel was dropped and the subsea camera was deployed to observe the reentry system during drilling. Hole U1481A was spudded at 1500 h, and the end of the casing had reached 264.1 mbsf at midnight (with ~464 m left to drill in).
We sampled Hole U1480G igneous rocks for postcruise analyses. Paleomagnetic measurements of Hole U1480H discrete samples are ongoing. The scientists worked on their Site U1480 reports, and participated in a science seminar on low-rigidity behavior of trench sediments.
Daily Science Report for 8 September 2016
Location: Hole U1481A (2°45.2857′N, 91°45.5771′E, 4182.7 m water depth; proposed Site SUMA-12A)
Science Update: The rig floor was secured for transit, the beacon was retrieved at 0109 h, and the thrusters were raised. The vessel was underway at 0212 h and arrived at Site U1481 at 0436 h. A few days in advance, the science party had requested and received permission by the Environmental Protection and Safety Panel (EPSP) and the TAMU Safety Panel to drill down at Site U1481 without coring the shallow section. Upon arrival at the site, preparations started immediately for deploying a reentry system. The upper guide horn was removed and stored, the Hydraulic Release Tool (HRT) and casing hanger were made up, and the welded mud skirt was moved to the moonpool. Between 1200 and 2200 h, we assembled 56 joints (728.2 m) of 10¾ inch casing. By midnight, the casing string had been landed in the moonpool.
All Hole U1480H cores have been measured on the whole-round and section-half loggers, and sampled for shipboard and postcruise analyses. Paleomagnetic measurements of discrete samples are ongoing and moisture and density measurements are completed through Core 11H.
Cores U1480H-11H to 14H contain dark gray silty clay with normally graded silt and fine sand layers and a few very thick beds of fine to medium sand. Starting with Core 15H, dark gray fine to medium sand layers dominate the lithology, and intercalated fine to medium beds of silty clay are also present.
Daily Science Report for 7 September 2016
Location: Hole U1480H (3°2.0555′N, 91°36.3482′E, 4147.3 m water depth; proposed Site SUMA-11C)
Science Update: Cores U1480H-7H to 17H advanced from 52.0 to 129.4 mbsf with 69.4 m recovered (96%; Core 141 was a drilled interval from 101.5 to 106.5 mbsf). APCT-3 formation temperature measurements were taken with Cores 7H, 10H, 12H, and 17H. Coring was terminated after reaching our target depth. The drill string was raised to the surface and the bit reached the rig floor at 2359 h. With science operations completed at Site U1480, we will proceed to proposed site SUMA-12A, which is 19 nmi from here.
All Hole U1480H cores have been measured on the whole-round loggers. Cores 1H–15H have been measured on the section-half loggers and sampled for shipboard and postcruise analyses.
Hole U1480H resampled the sediment sequence of Hole U1480E. Cores 1H to 3H are composed mainly of mottled pale yellow to brown calcareous silty clay, ooze, and clay with numerous intercalated fine-grained silty sand layers and several ash layers. A thick ash layer in Section 4H-3 marks a change to a dark gray silty clay containing numerous, normally graded silt and fine sand layers that alternate with very thick beds of fine to medium sand. Bedding dips are subhorizontal.
Daily Science Report for 6 September 2016
Location: Hole U1480H (3°2.0555′N, 91°36.3482′E, 4147.3 m water depth; proposed Site SUMA-11C)
Science Update: We continued raising the drill string to the surface, and Hole U1480G ended when the end of the drill string reached the rig floor at 0510 h. We then spent several hours making up an APC/XCB bottom-hole assembly and lowering the drill string to just above the seafloor. Hole U1480H was spudded at 1545 h at 4147 m water depth. Cores U1480H-1H to 6H advanced from 0 to 52 mbsf with 46.6 m recovered (90%). An APCT-3 formation temperature measurement was taken with Core 4H. Coring at this hole is planned to 150 mbsf to refine the biostratigraphy, magnetostratigraphy, and geochemistry of the shallow section at Site U1480.
Most measurements have been completed for Hole U1480G. All cores through Core U1480H-3H have been measured on the whole-round loggers. Core 1H was measured on the section-half loggers and sampled for shipboard and postcruise analyses.
Cores U1480G-72R to 73R consist of massive, crystal-poor, very fine-grained, dark gray basalt. Following the conclusion of coring in Hole U1480G, we have been able to define all lithologic units at Site U1480 from the seafloor to the igneous basement.
Daily Science Report for 5 September 2016
Location: Hole U1480G (3°2.0550′N, 91°36.3370′E, 4147.5 m water depth; proposed Site SUMA-11C)
Science Update: The day started with the crew continuing their efforts to free the drill string, which was accomplished at 0155 h with 150 klbs of overpull. The top drive was set back and the end of the drill string was raised to 63 mbsf for logging. The resistivity and gamma ray tools were rigged up (0530–0800 h) and lowered into the hole. Fill was encountered at 809.3 mbsf, 52.2 m below the end of the casing, and one logging pass was made from that depth to the seafloor. The logging tools were back at the surface by 1630 h. The rest of the day was spent pulling the drill string out of the hole. The end of the drill pipe cleared the seafloor at 1945 h and was at 2179 m below the rig floor at midnight.
All cores from Hole U1480G have been measured on the whole-round and section-half loggers. Description and limited shipboard sampling have been completed but sampling of igneous rocks for postcruise analyses will be done at a later time. P-wave velocity and thermal conductivity have been measured through Core 71R.
Cores U1480G-65R (Section 4) through 69R (Section 5) contain partially altered, porphyritic igneous rocks with numerous horizontal to subvertical veins of calcite. Alternating dark reddish brown to black calcareous ooze and calcareous clay with silt reappear from Core 69R (Section 5) to Core 71R (Section 2). The lower part of Core 71R consists of three beds of basalt separated by recrystallized calcareous ooze.
Daily Science Report for 4 September 2016
Location: Hole U1480G (3°2.0550′N, 91°36.3370′E, 4147.5 m water depth; proposed Site SUMA-11C)
Science Update: Cores U1480G-71R to 73R advanced from 1412.1 to 1431.6 mbsf with 8.7 m recovered (44%). Coring ended in igneous basement, following indications that the drill bit had failed after 77 operating hours. The bit was released in the hole at 1305 h, and the end of the drill string was raised to 1249.3 mbsf. In preparation for logging, 300 barrels of heavy mud were pumped in the hole, and the drill string was raised again to 1161.3 mbsf and the top drive was set back at 1945 h. At that point it became evident that sand had collapsed into the hole, trapping the drill string. Attempts to free the drill string with 150 klbs overpull failed, and the top drive was engaged again at 2145 h to try to free the drill string with rotation and circulation. The day ended with the crew trying to free the drill string (which they were able to do at 0150 h).
All cores from Hole U1480G have been measured on the whole-round loggers. Description, section-half logger measurements, and sampling are being done out of sequence based on core lithology. Cores 61R–63R were sampled collectively for shipboard and postcruise analyses. P-wave velocity and thermal conductivity have been measured through Core 65R.
Core U1480G-62R consists of igneous rocks in the upper part, and matrix-supported tuffaceous sandstones and conglomerates in the lower part. Core 65R contains alternating layers of tuffaceous ooze and calcareous ooze with recrystallized agglutinated foraminifers in the upper part and igneous rocks in the lower part.
Daily Science Report for 3 September 2016
Location: Hole U1480G (3°2.0550′N, 91°36.3370′E, 4147.5 m water depth; proposed Site SUMA-11C)
Science Update: Cores U1480G-66R to 70R advanced from 1366.4 to 1412.1 mbsf with 38.8 m recovered (85%). We anticipate starting downhole logging tomorrow.
All cores through Core U1480G-69R have been measured on the whole-round loggers. P-wave velocity and thermal conductivity have been measured through Core 62R, and moisture and density measurements are completed through Core 60R.
Core U1480G-61R consists of moderately bioturbated light brown to brown tuffaceous silty clay with transparent glass, alternating with decimeter-scale intervals of calcareous ooze with parallel-laminated very thin beds and laminae of ash and tuffaceous silt. Cores 61R–62R have faults in a variety of orientations and cross-cutting relationships that suggest the faults are nearly contemporaneous.
Daily Science Report for 2 September 2016
Location: Hole U1480G (3°2.0550′N, 91°36.3370′E, 4147.5 m water depth; proposed Site SUMA-11C)
Science Update: Cores U1480G-59R to 65R advanced from 1298.3 to 1366.4 mbsf with 40.3 m recovered (59%). Hole conditions remain good. At the conclusion of coring in this hole, we will proceed with downhole logging.
All cores through Core U1480G-60R have been measured on the section-half loggers, described, and sampled for shipboard and postcruise analyses. Discrete samples for P-wave velocity and thermal conductivity have been measured through Core 60R, and moisture and density measurements are completed through Core 53R.
Cores 55R to 57R are dominated by bioturbated dark green and reddish brown clay with mm-scaled laminae of silt. Starting with Core 58R, reddish brown clay with intervals of greenish gray silty clay and very thin beds of intercalated ash layers dominates the lithology. The lowermost part of Core 60R contains medium beds of white calcareous ooze. Bedding dips remain near horizontal, and Core 60R contains small faults and shear zones. Core 60R is of Oligocene age.
Daily Science Report for 1 September 2016
Location: Hole U1480G (3°2.0550′N, 91°36.3370′E, 4147.5 m water depth; proposed Site SUMA-11C)
Science Update: Cores U1480G-52R to 58R advanced from 1238.0 to 1298.3 mbsf with 52.6 m recovered (87%). Hole conditions remain good. The goal in this hole is to core until we reach the sediment/basement interface (anticipated at 1450 mbsf) plus 10 m into basement.
All cores through Core U1480G-55R have been measured on the section-half loggers, described, and sampled for shipboard and postcruise analyses. Discrete samples for P-wave velocity and thermal conductivity have been measured through Core 55R, and moisture and density measurements are completed through Core 46R.
Cores U1480G-49R to 53R are dominated by fining upward sequences of slightly bioturbated, black to very dark gray, normally graded silty clay to clay, with variable amounts of silt as well as intercalated sand layers containing mud clasts and plant fragments. Starting with Core 54R the lithology is dominated by slightly bioturbated, dark green and reddish brown clay, with the reddish brown clay increasing with depth. Core 52R is of late Miocene age.