Annotated record of the detailed examination of Mn deposits in the Mid-Atlantic Ridge during the IPOD Atlantic Site Survey near DSDP Leg 45, Site 395

One of the main objectives of the International Phase of Ocean Drilling (IPOD) of the Deep Sea Drilling Project was to determine the geological, geochemical, and geophysical character of ocean crust formed at mid-ocean spreading ridges. A series of drill holes along the Mid-Atlantic Ridge (MAR), from near Iceland south to approximately 22°N latitude, was planned to compare the crust being generated near an anomalous ridge (Iceland) with that originating near a normal slow-spreading ridge (22°N). At the same time, a series of holes in near zero-age crust at 22 °N was planned along a "flow line" (a transect parallel to local fracture zones) trending west into increasingly older crust, eventually extending the sampling to crust of apparent Jurassic date off the eastern United States coast. This age-transgressive transect was designed to test the evolution of crust formed at one point in the spreading ridge. The intersection of these two series of holes was designated Atlantic Site 5 and was positioned on the upper western flank of the Mid Atlantic Ridge near 22 °N latitude, as close as possible to the spreading ridge crest. The R/V Kana Keoki conducted a detailed 22-day survey of Atlantic Site 5 during Cruise 74-01-01, Leg 7 prior to the DSDP Leg45 was conducted.