JA Daily Science Report for Expedition 309, 19 July 2005


LOCATION: Site 1256


SCIENCE UPDATE: The drill string was lowered to 4370 mbrf (725 mbsf), a center bit installed, and Hole 1256D washed and reamed to remove fill at the bottom. The drill string began taking weight at 4395 mbrf (750 mbsf), the center bit was retrieved, a 50 barrel mud sweep of 90 viscosity sepiolite was pumped down to clean the hole, and enough strokes were applied to ensure the mud pill had cleared. The core barrel was dropped and RCB coring began from 752 to 753.9 mbsf to adjust the space-out for the kelley. Core 1256D-75R was on deck at 0945 with 1.3 m of recovery. Coring continued from 753.7 to 755.7 (Core 76R) with 1.23 m of recovery at 1425 and from 755.7 to 763.5 mbsf (Core 77R) with 1.65 m of recovery at 2030. Rate of penetration is between 1 to 1.5 m/hr. Cores 75R and 76R are aphyric, cryptocrystalline to microcrystalline, slightly altered dark grey basalt sheet flows separated by chilled margins, broadly similar to basalts recovered at the end of Leg 206.