JA Daily Science Report for Expedition 312, 27 November 2005


LOCATION: Site 1256


SCIENCE UPDATE: Cores 189R and 190R recovered 1 m of basalt from 1333.9 to 1343.5 mbsf representing an average recovery of 10.4% at a grueling pace of 0.6 m/hr. One small cobble was jammed in the upper core catcher during retrieval of Core 190R after an advance of 4.8 meters in 10 hours. The jammed cobble had to be cut free of its prison with a grinder in the core tech shop. Unable to escape past the jammed cobble above into the core barrel, a second small basalt piece had noticeable abrasions on its periphery where the lower core catcher dogs had chewed the outer surface. Most recovered igneous contacts are composite structures with chilled margins, breccias, and alteration. In Cores 188R through 189R (1329 to 1333 mbsf) there are fewer structures as primary grain size increases. Several oriented pieces are present in Core 189. At 2115 hr the bit had accumulated 49.4 hrs of rotation so the pipe was tripped for a bit change.