Daily Report for IODP Expedition 311, October 18, 2005
LOCATION: Site U1325 (CAS-02C)
SCIENCE UPDATE: By midnight Hole U1325B had been advanced by a combination of APC, XCB, and pressure coring (PCS, HRC) to a depth of 140.5 mbsf. We successfully cored most of the upper 72 mbsf with the APC system and had three deployments of the APC temperature tools (APC3) that returned very high quality data. At 71.5 mbsf we had an incomplete stroke of the APC and switched to XCB coring. The first pressure core (PCS) was taken at 82.4 mbsf but did not return with a pressurized core. In Core U1325B-10X (~73 mbsf) we found the first evidence of gas hydrates at this site with the occurrence of several small, IR imaged cold spots. Since Core U1325B-10X, we have found in most every core cold spots measuring ~5 to 10 cm thick. Cold sections typically are associated with sand layers. Temperatures in the IR imaged gas-hydrate-bearing sands are reduced by up to 4° C below background and show reduced pore-water salinities as low as 22. An HRC was deployed at 129.9 mbsf but did not return core under pressure. With the completion of the VSP survey at Site U1328, the marine mammal observer, Scott Toews, returned to shore via helicopter at 12:30 hr.