TO: Tom Davies
FM: Jay Miller
JA Daily Science Report for Expedition 305, 23 January 2005.
SCIENCE UPDATE: Cores 305-U1309D-125R to -130R (616.6 to 645.4 mbsf, 81% recovery) are predominantly coarse-grained gabbro, with intervals of pegmatitic gabbro, medium- to coarse-grained olivine-bearing gabbro, and coarse-grained oxide gabbro. A diabase dike with a sharp upper contact and a sharp but crenulate lower contact intrudes the gabbro. A second interval of diabase has a subvertical, sharp but wavy contact through the middle part of the cored interval. Alteration is heterogeneous throughout; some intervals are fresh, others pervasively altered. Epidote is commonly present in patches throughout the cored interval. There are some intervals (tens of cm thick) with strong foliation but, particularly in the coarser grained gabbros, evidence of deformation (other than low strain cataclasis) is rare.