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IODP Expeditions 367 and 368

South China Sea Rifted Margin


Daily Science Report for 21 February 2017

Location:
Hole U1499A (18°24.5698′N, 115°51.5881′E; proposed Site SCS-14A)
Hole U1499B (18°24.5724′N, 115°51.6000′E [preliminary]; proposed Site SCS-14A)

Science Update: Our day started with removing Core U1499A-68X from the drill string; it was empty. It had penetrated the formation very quickly, so we suspected sands and very low recovery. In addition, it spent ~24 h inside the drill pipe 100 m below the ship while the drawworks was repaired. Cores 69X–71X then penetrated quite slowly from 647.4 to 659.2 m and recovered 1.8 m of hard sedimentary rock (a good depth for the base of the casing). The driller then circulated the entire hole with mud to minimize risks of hole problems as we pulled the drill string out of the hole. We kept the top drive installed until the bit was at 299 m, above the uppermost interval of unconsolidated sands. The bit cleared the seafloor at 1230 h and arrived on the rig floor at 2015 h, ending Hole U1499A. We then offset the ship 20 m to the east and conducted required routine rig servicing (drill line slip and cut). Just before midnight, we started preparing the rig floor for assembling the Hole U1499B reentry cone and casing system we plan to drill 651 m into the seafloor. Cores 69X–71X are late Miocene claystone with thin clayey silt and foraminifer-rich silt interbeds.


Daily Science Report for 20 February 2017

Location: Hole U1499A (18°24.5698′N, 115°51.5881′E; proposed Site SCS-14A)

Science Update: We spent nearly the entire day repairing the low clutch diaphragm on the drawworks. Since we couldn’t raise the drill string and the bit was near the bottom of the hole (~647 m), we kept circulating, rotating, and pumping mud sweeps every hour to keep the drill string from getting stuck. After the repair was completed at 2315 h, we were finally able to open the drill string and get Core 68X out of the drill string. We had suspected it would be empty since it cored through inferred sands, but it also had been sitting in the drill string for a full day. At the end of the day, we dropped a core barrel to resume XCB coring. Our main objective now remains to penetrate a couple more cores to verify an appropriate formation for the base of the casing to be deployed in our next hole (firm formation, not sands). Scientists continued processing samples, data, and synthesizing data between laboratories.


Daily Science Report for 19 February 2017

Location: Hole U1499A (18°24.5698′N, 115°51.5881′E; proposed Site SCS-14A)

Science Update: We continued XCB coring in Hole U1499A throughout the day. Cores 58X to 67X penetrated from 540.7 to 637.7 m (20.37 m recovered; 21%). For the first eight cores (58X–65X), the bit penetrated very quickly through 77.6 m and recovered only 4.16 m (5%), so we infer this is predominantly unconsolidated sands. Core 66X had slower penetration and complete recovery in finer-grained formation. However, the penetration rate increased again in Core 67X, indicating that we encountered sands again. The last core of the day (68X) also cut very quickly and had almost arrived back on the rig floor when the low clutch diaphragm in the drawworks failed at 2245 h. The crew started repairs immediately. We can’t raise the drill string in this water depth with ~640 m of drill string below the seafloor until the repair is completed. We are circulating and rotating, as well as pumping a mud sweep every hour to keep the drill string from getting stuck. We also can’t recover Core 68X—which is still in the drill string 100 m below the ship—until the repair is complete.

Cores 47X to 67X have been split and span both the well-recovered intervals composed of clay with thin foraminifer-rich silt interbeds as well as the poorly recovered intervals inferred to be predominantly sand. The limited core from those poorly recovered intervals contains some sand but also clay with thin foraminifer-rich silt interbeds. The base of the recovered interval still appears to be late Miocene.


Daily Science Report for 18 February 2017

Location: Hole U1499A (18°24.5698′N, 115°51.5881′E; proposed Site SCS-14A)

Science Update: We continued XCB coring throughout the day. Cores 46X to 57X penetrated from 424.3 to 540.7 m (47.91 m recovered; 41%). Cores 46X–49X returned with 100% recovery, but while cutting Core 50X, we encountered a substantial formation change and the bit started to penetrate very quickly—another interval of inferred sands. The rest of the cores taken today (51X–57X) penetrated 67.7 m of formation very quickly and only recovered 1.82 m (3%). The presence of these sands is generally consistent with the seismic data. We circulated 30 barrels of mud on Cores 47X, 50X, 53X, 55X, and 57X. While making a connection after recovering Core 53X, the drill string became stuck and could not be rotated. We circulated an additional 50 barrels of mud and we were able to regain rotation and resume coring. Cores 30X to 47X have been split and span both the well-recovered intervals composed mostly of clay with thin silt interbeds with varying proportions of foraminifers as well as the poorly-recovered intervals inferred to be predominantly sand. The base of Core 57X is late Miocene.


Daily Science Report for 17 February 2017

Location: Hole U1499A (18°24.5698′N, 115°51.5881′E; proposed Site SCS-14A)

Science Update: We continued XCB coring throughout the day. Cores 31X to 45X penetrated from 278.8 to 424.3 m (74.97 m recovery; 52%). Core recovery was good (90%–100%), except we encountered a substantial formation change between 333.8 and 404.9 m when Cores 37X to 43X recovered only 1.37 m (2%). The bit penetrated very quickly through this interval which appears to contain relatively unconsolidated sand. We circulated 30 barrels of mud on Core 37X, 38X, 41X, 44X, and 47X. Cores 18H to 30X have been split and contain predominantly clay with very thin silt interbeds. The base of Core 45X is late Miocene.


Daily Science Report for 16 February 2017

Location: Hole U1499A (18°24.5698′N, 115°51.5881′E; proposed Site SCS-14A)

Science Update: We continued with APC/XCB coring from 102.5 to 278.8 m (165.54 m recovery; 94%). APC Cores 12H–18H (102.5 to 162.4 m) encountered increasingly firm formation and the core barrel did not fully penetrate the formation for many of them. All APC cores were oriented and we made formation temperature measurements (APCT-3) on Cores 12H and 14H. Due to our primary expedition objectives, we switched to XCB coring instead of first using the half-length APC system which would take twice as long. XCB Cores 19X to 30X penetrated from 162.4 to 278.8 m and recovered 104.78 m (90%). Core recovery was quite high for each XCB core (86%–100%), except for Core 25X which came back with only 2 cm of core. The core liner appeared to have had sediment in it, so we suspect it fell out of the barrel while retrieving the core barrel.

Cores 7H to 18H have been split and described. Cores 7H–11H are predominantly nannofossil ooze below which the formation changes to clay with silt with numerous relatively thin silt layers. Significantly deformed bedding in Cores 8H–11H likely represents a mass transport deposit. Although there is significant reworking, a tentative Pliocene age has been assigned to the base of Core 37X.


Daily Science Report for 15 February 2017

Location: Hole U1499A (18°24.5698′N, 115°51.5881′E; proposed Site SCS-14A)

Science Update: We continued lowering the bit to the seafloor until 0645 h, when we installed the top drive, adjusted the drill string length to position the bit for taking the first core, and pumped a pig through the drill string to clean out some of the rust. Coring in Hole U1449A started at 0930 h. Core U1499A-1H recovered 7.5 m, so the seafloor depth is 3760.2 mbsl. APC Cores 1H–11H penetrated from the seafloor to 102.5 m and recovered 106.75 m (104%). All APC cores were oriented and we made formation temperature measurements (APCT-3) on every other core starting with Core 4H. Cores 1H to 6H have been split and described and are predominantly Pleistocene clay with silt, with graded beds of silt and sand, except for the lower part of Core 6H where the formation changes to clay-rich nannofossil ooze.


Daily Science Report for 14 February 2017

Location:
In transit
Arrived at Site U1499 (proposed Site SCS-14A)

Science Update: After a 277 nmi transit from Hong Kong, we arrived at Site U1499 at 1615 h. We lowered the thrusters, put together the APC/XCB bottom-hole assembly, and started lowering it to the seafloor in preparation for coring. At midnight, the bit had reached 537 m below the rig floor. The Curator and Laboratory Officer introduced the scientists to core flow and sampling. During the noon crossover, the scientists were given an overview of the Iberia–Newfoundland hyperextended rifted margins.


Daily Science Report for 13 February 2017

Location:
China Merchants Wharf, Hong Kong
In transit to Site U1499 (proposed Site SCS-14A)

Science Update: Throughout the early morning, the ship’s crew completed securing all equipment. The laboratory groups continued learning their laboratories and preparing their instruments/​methods. After immigration activities were completed, the last line was released at 1215 h and the rest of the day was spent in transit to Site U1499 (proposed Site SCS-14A). In the afternoon, the Co-Chief Scientists gave a presentation on the Site U1499 (SCS-14A) science objectives and what we expect to encounter.


Daily Science Report for 12 February 2017

Location: China Merchants Wharf, Hong Kong

Science Update: In the morning, the JRSO Curator introduced the scientists to core curation and sampling, the JRSO Imaging Specialist introduced the core describers to the microscope capabilities, and the micropaleontologists met with the JRSO Core Description Specialist to start setting up their software. Since our departure is set for tomorrow (13 February), the scientists were given the afternoon off. We completed loading remaining operations hardware including 288 joints of drill pipe, spooling of new coring line onto the forward coring winch, offloading of trash prior to sailing, and continued securing all equipment for heading out to sea.


Daily Science Report for 11 February 2017

Location: China Merchants Wharf, Hong Kong

Science Update: In the morning, the JRSO Operations Superintendent introduced the scientists to drilling and coring operations, our Educator and Journalist gave an overview of their plans for the expedition, and the Captain held the first fire and boat safety drill. In the afternoon, the scientists were introduced to downhole measurements and then shared their individual research interests for the expedition with each other. Loading of essential hardware (casing, reentry cones, etc.), continued throughout the day. Due to the late arriving essential hardware, our departure has been delayed by 1 d and is now scheduled for the day after tomorrow (13 February).


Daily Science Report for 10 February 2017

Location: China Merchants Wharf, Hong Kong

Science Update: Scientists were introduced to shipboard deliverables/obligations and then broke up into laboratory groups to meet with their JRSO technical staff team members. After the Captain’s introduction and safety orientation and a core flow tour, they resumed laboratory team meetings. In addition to routine loading/offloading, trucks with our delayed shipment of essential hardware (casing, reentry cones, etc.) started arriving in the late afternoon. We are tentatively scheduled to depart in the morning of 13 February.


Daily Science Report for 9 February 2017

Location: China Merchants Wharf, Hong Kong

Science Update: Today began with introductions of the Expedition 367 scientists and JRSO shipboard staff, followed by a presentation of the expedition scientific objectives by the Co-Chief Scientists. The rest of the day’s meetings had to be postponed until tomorrow so that seven scientists could address issues with their travel documents. Major port call activities included loading of drilling mud, sea freight, food, and offloading of frozen shipments from the previous expedition. Due to a missed boat transfer in Shanghai, our shipment of essential hardware (reentry cones, casing, mud motors, etc.) is planned to arrive tomorrow. This may delay our departure that was scheduled for 12 February.


Daily Science Report for 8 February 2017

Location: China Merchants Wharf, Hong Kong

Science Update: The Expedition 367 scientists boarded the ship in the morning, got settled in their rooms, were introduced to life on board the JOIDES Resolution, and participated in an initial laboratory and ship safety tour. In the afternoon, the scientists were introduced to the information technology on board the ship and started to connect their computers to the shipboard network. The day ended with a core flow tour for half of the science party. Transfer of incoming and outgoing shipments continued throughout the day.


Daily Science Report for 7 February 2017

Location: China Merchants Wharf, Hong Kong

Science Update: The South China Sea Rifted Margin Expedition 367 started at 0812 h with the first line ashore at the China Merchants Wharf in Hong Kong. The Co-Chief Scientists and IODP staff moved onto the ship and started crossover with their Expedition 366 counterparts. Initial loading of incoming shipments began.