Site U1426

Abstract

Four holes were cored at Site U1426 (proposed Site YB-2) using the full and half advanced piston corer (APC) and the extended core barrel (XCB) (Table T1; see also Fig. F2 in the "Expedition 346 summary" chapter [Tada et al., 2015a]). Holes U1426A, U1426B, U1426C, and U1426D were cored to 396.7, 34.7, 204.0, and 99.4 m CSF-A (see the "Methods" chapter [Tada et al., 2015b]) and recovered 418.78, 35.82, 211.89, 103.71 m of core, respectively. A total of 95 APC and 2 XCB cores obtained 770.2 m of sediment (104.8% recovery). The advanced piston corer temperature tool (APCT-3) was deployed four times. Transit from Site U1425The 148 nmi transit to Site U1426 was covered in 13.4 h at an average speed of 11 kt. Sea passage ended at 0636 h on 3 September 2013. The vessel was maneuvered over the location coordinates, thrusters were lowered into position, and the vessel was turned over to dynamic positioning control. By 0715 h, the vessel was stabilized for rig floor operations to begin. A Falmouth Scientific positioning beacon (model BAP-547; SN1028W, 16 KHz, 206 dB) was deployed at 0822 h. Hole U1426AA three-stand APC/XCB bottom-hole assembly was assembled, and the drill string was run to the seafloor. After picking up the top drive and spacing out the drill string to 907.4 meters below rig floor (mbrf), which was 6.0 m deeper than the depth provided by the precision depth recorder, an APC core barrel was deployed. The first core barrel recovered 2.47 m of core, establishing a seafloor depth of 914.4 mbrf. Oriented APC coring continued using full-length nonmagnetic core barrels through Core 346-U1426A-28H at 256.2 m CSF-A. At this depth, the APC was switched to the half APC (4.7 m) system, and coring continued through Core 37H (297.0 m CSF-A), where a solid dolomite layer was encountered. The XCB was picked up and used to cut a 1.0 m core (38X) until breaking through the layer of resistance. Half APC coring resumed from that point and continued through Core 59H (396.7 m CSF-A). The hole was displaced with 160 bbl of 10.5 ppg mud. The top drive was set back, and the drill string was pulled clear of the seafloor at 2330 h on 4 September 2013, ending Hole U1426A. Total recovery for this hole was 418.78 m (105.6%). A total of 29 half APC cores were recovered. Four successful temperature measurements were taken using the APCT-3 temperature shoe at 31.0, 59.5, 88.0, and 116.5 m CSF-A, respectively.

Integrated tephrostratigraphy and stable isotope stratigraphy in the Japan Sea and East China Sea using IODP Sites U1426, U1427, and U1429, Expedition 346 Asian Monsoon

“…Some darker layers are thinly laminated. Calcareous microfossil preservation is relatively good in the upper part of the succession at this site compared with deeper sites, although foraminifera are poorly preserved or absent in some intervals (Tada et al 2015b). Several tephra layers occur in the succession.…”

“…2a). The organic-rich darker layers generally display a sharp base, whereas the upward transition from dark to light layers is gradational and commonly strongly bioturbated (Tada et al 2015b). Some darker layers are thinly laminated.…”

Data report: reanalysis of interstitial water barium, iron, and sulfur concentrations at Sites U1426 and U1427

“…While principally drilled for paleoceanographic objectives, an additional focus at these sites in the southern marginal sea was generation of high-resolution IW profiles for a wide array of dissolved species. This mission was accomplished, but as noted in the "Site U1426" and "Site U1427" chapters (Tada et al, 2015b(Tada et al, , 2015c, there were some data irregularities with shipboard SO 4 2-and Ba measurements (Fig. F2).…”

“…On the ship, this included salinity, alkalinity and pH, major anions (Cl -, SO 4 2-, Br -) and cations (Ca, Mg, K, Na), minor elements (B, Ba, Fe, Li, Mn, Sr), ammonium (NH 4 + ), phosphate (PO 4 3-), silica (H 4 SiO 4 ), hydrogen sulfide (HS -), and "yellowness." The results of these analyses were presented in the "Site U1426" and "Site U1427" chapters (Tada et al, 2015b(Tada et al, , 2015c.…”

“…Site U1426 is located at 37°2.00′N, 134°48.00′E, and 902 m water depth at the same location as ODP Site 798. Four holes at Site U1426 penetrated 396, 34, 204, and 99 meters below seafloor (mbsf) with recovery <100% (see the "Site U1426" chapter [Tada et al, 2015b]). Site U1427 is located at 35°57.92′N, 134°26.06′E, and 330 m water depth.…”