TO: Tom Davies
FM: Jay Miller
JA Daily Science Report for Expedition 305, 8 February 2005.
SCIENCE UPDATE: Cores 305-U1309D-201R to -206R (969.7 to 994.2 mbsf, 90% recovery) are predominantly medium- to coarse-grained gabbro. Contacts between grain size changes are, in places, sharp and range from subhorizontal to steeply dipping in the core reference frame. However, in some cases transitions between medium- and coarse-grained intervals are gradational. Modal changes are rare, with olivine-rich and olivine-bearing intervals of few tens of centimeters thick, and even more rare thin oxide-bearing intervals. The bottom of Core U1309D-205R and the top of Core U1309D-206R (~990 mbsf) contain a moderately altered diabase at least 1 m thick, intruded into medium-grained olivine gabbro.