JA Daily Science Report for Expedition 309, 28 July 2005
LOCATION: Site 1256
SCIENCE UPDATE: Cores 101R to 103R recovered 5.52 m of basalts from 917.0 to 940.8 mbsf (23.2%). Drilling times increased to over 9 hours for Cores 101R and 102R (9.6 m cored). In both cases the first ~4 m cored in 2-3 hours followed by much slower rates of penetration. We decided to proceed by taking half cores (4.8 m cored) since the wireline trip takes only 80 min from the time we pull off bottom until the time there is weight on bit. The rocks are cryptocrystalline to fine grained basalt sheet flows less than 3 m thick. The continued presence of glass indicates these rocks were erupted onto the ocean floor. Vertical fractures filled with green phyllosilicates and silica minerals occur locally. During the next bit change shipboard sampling will take place for the cores recovered so far. With the changing of the bit we hope to reveal the next chapter in our epic quest for rocks beneath the extrusive lavas.