Core recovery and depths This chapter presents the methods for our shipboard observations. It also enables the interested investigator to identify data and select samples for further analysis. The information presented here concerns only shipboard operations and analyses described in the site chapters. Methods used by various investigators for shore-based analyses of Integrated Ocean Drilling Program (IODP) Expedition 336 data will be described in individual publications in various professional journals and the "Expedition research results" chapters of this Proceedings volume. This introductory section provides an overview of operations, curatorial conventions, and general core handling and analysis. Site locations At all Expedition 336 sites, GPS coordinates from a precruise site survey (Schmidt-Schierhorn et al., 2012) were used to position the R/V JOIDES Resolution on site. The only seismic system used during the cruise was the Syquest Bathy 2010 CHIRP subbottom profiler, which was monitored on the approach to each site to confirm the seafloor depth agreed with that from the precruise survey. Once the vessel was positioned at a site, the thrusters were lowered and a positioning beacon was dropped to the seafloor. The dynamic positioning control of the vessel uses navigational input from the GPS and triangulation to the seafloor beacon, weighted by the estimated positional accuracy (Fig. F1). The final hole position was the mean position calculated from the GPS data collected over the time that the hole was occupied. Drilling operations The advanced piston corer (APC), extended core barrel (XCB), and rotary core barrel (RCB) systems were used during Expedition 336. These standard coring systems and their characteristics are summarized in Graber et al. (2002). The APC system cuts soft sediment cores with minimal coring disturbance relative to other IODP coring systems. After the APC core barrel is lowered through the drill pipe and lands near the bit, the drill pipe is pressured up until the two shear pins that hold the inner barrel attached to the outer barrel fail. The inner barrel then advances into the formation and cuts the core. The driller can detect a successful cut, or "full stroke," from the pressure gauge on the rig floor. The XCB system is deployed when the formation becomes too stiff for the Methods 1 Expedition 336 Scientists 2 Chapter contents
