IODP Expedition 368X
Return to Hole U1503A (South China Sea)
Daily Science Report for 8 December 2018
Location: China Merchant Wharf, Hong Kong
Science Update: We completed the 284 nmi transit from Hole U1503A to Hong Kong and the pilot came aboard at 0700 h. The first line was ashore at 0806 h, ending Expedition 368X.
Daily Science Report for 7 December 2018
Location: In transit to China Merchant Wharf, Hong Kong
Science Update: At 0000 h we secured the thrusters and prepared for departure from Hole U1503A. We switched to cruise mode and started the 284 nmi transit to China Merchant Wharf, Hong Kong, at 0030 h.
The science party finalized site reports for Hole U1503A.
Daily Science Report for 6 December 2018
Location: Hole U1503A (18°8.6300′N, 116°18.8456′E; water depth 3868 m; proposed Site SCSII-9B)
Science Update: At 0400 h we began the setup for logging with the Vertical Seismic Imager (VSI) tool. The VSI tool string was lowered into Hole U1503A, and at 0630 h the protective species watch began. A soft ramp up of the seismic guns began at 0750 h and gun control was turned over to the Schlumberger engineer at 0820 h. VSI measurements began at 975 mbsf and we worked progressively upward in 50 m increments. By 1055 h we had completed 18 stations (from 975 to 125 mbsf) with good results. The logging tools were returned to the rig floor and we began to pull out of the hole. At 1450 h the drill pipe cleared the seafloor and we continued to trip pipe back to the rig floor in preparation to depart Hole U1503A.
The science party continued to finalize site reports for Hole U1503A.
Daily Science Report for 5 December 2018
Location: Hole U1503A (18°8.6300′N, 116°18.8456′E; water depth 3868 m; proposed Site SCSII-9B)
Science Update: Cores 87R to 88R penetrated 1691.0–1710.1 m and recovered 8.9 m (47%). We then began preparations to log the cased portion of hole (end of casing at 995.1 m) with the Vertical Seismic Imager (VSI) tool. At 0645 h we began to pull out of the hole. While reaming the hole to 1383 m, we experienced overpull and high torque on the drill string. After 200 barrels of mud were pumped in to maintain hole stability, we continued to pull out of the hole and cleared the seafloor at 1450 h. The subsea camera was deployed and at 1920 h the drill bit was dropped onto the seafloor. We reentered Hole U1503A at 2155 h and the drill pipe was lowered to 71 m inside the hole in preparation for logging.
Cores 84R to 88R consist of sparsely plagioclase phyric basalt. Chilled margins are observed in Core 87R, and Cores 87R and 88R contain haloed veins of iron oxide and calcite.
Daily Science Report for 4 December 2018
Location: Hole U1503A (18°8.6300′N, 116°18.8456′E; water depth 3868 m; proposed Site SCSII-9B)
Science Update: Cores 82R to 86R penetrated 1662.2–1691.0 m and recovered 15.28 m (53%). Penetration rates averaged 2.9 m/h.
Cores 80R to 83R consist of sparsely to moderately plagioclase phyric basalts. Several intervals of claystone and nannofossil-bearing claystone are also present, but are located at the top of cores and considered possible fall-in (drilling disturbance).
The science party continued to finalize site reports for Hole U1503A.
Daily Science Report for 3 December 2018
Location: Hole U1503A (18°8.6300′N, 116°18.8456′E; water depth 3868 m; proposed Site SCSII-9B)
Science Update: Cores 76R to 80R penetrated 1633.0–1657.2 m and recovered 11.9 m (49%). We then began experiencing high torque and pressure on the drill string and pulled back to 1566.0 m. After an hour of washing and reaming from 1566.0 to 1657.2 m, 40 barrels of high viscosity mud were pumped to clean the hole. We resumed coring at 1915 h and Core 81R penetrated 1657.2–1662.2 m and recovered 2.1 m (42%).
Cores 76R to 79R consist of sparsely to moderately plagioclase phyric basalts. Several intervals of claystone and nannofossil-bearing claystone are also present.
The Expedition Project Manager gave a presentation on the scientific and logistical tasks we need to accomplish during the final week of the expedition.
Daily Science Report for 2 December 2018
Location: Hole U1503A (18°8.6300′N, 116°18.8456′E; water depth 3868 m; proposed Site SCSII-9B)
Science Update: The drill pipe was lowered to 3855.4 m below the rig floor and at 0200 h the subsea camera was deployed. The secondary free-fall funnel was located and Hole U1503A was reentered at 0439 h. The subsea camera returned to the surface and the drill pipe was lowered into the hole until a bridge was encountered at 1375.0 m. After spending 8 h washing and reaming from 1345.0 to 1633.0 m, we resumed coring at 2100 h.
The science party continued to work on site reports for Hole U1503A, and our petrophysicist/observer gave a research presentation.
Daily Science Report for 1 December 2018
Location: Hole U1503A (18°8.6300′N, 116°18.8456′E; water depth 3868 m; proposed Site SCSII-9B)
Science Update: Core 75R penetrated 1628.0–1633.0 m and recovered 0.83 m (17%). At 0315 h we started operations to replace the drill bit. The pipe was raised to 1355.7 m within the open hole (casing extends to 991.5 m) and 200 barrels of heavy mud were pumped in to maintain hole stability. We continued to pull out of the hole and cleared the seafloor at 1050 h. By 1725 h the bottom-hole assembly (BHA) was back at the rig floor. The drill bit was replaced and the BHA was lowered to 2902 m below rig floor by the end of the day.
Core 75R consists of sparsely plagioclase phyric basalt. Drilling disturbance (fragmenting) varies from moderate to high. The science party participated in a video conference with the Expedition 367/368 Expedition Project Manager and Co-Chief Scientists to discuss the remaining operations at Hole U1503A.