Annotated record of the detailed examination of Mn deposits from DSDP Leg 26 (Sites 250A, 252, 256, 257)

DSDP Leg 26, is the fifth cruise of D/V Glomar Challenger in the Indian Ocean, and the first cruise of Phase III of the Deep Sea Drilling Project. The Indian Ocean is the smallest of the three major ocean basins but appears to be geologically the most complex. The sites drilled on Leg 26 were selected to try to elucidate a number of specific problems of both local and broad regional significance, as well as to add to the general knowledge of the area. In particular: a) To locate the oldest sediment in the Indian Ocean and thus possibly the date of the initial breakup of Gondwanaland (Sites 250, 256, 257); b) To determine the effects of the initiation of the Circumpolar Current on southern Indian Ocean sedimentation (Sites 250, 252, 256, 257, 258); c) To determine the history of spreading of the Southwest Branch of the Indian Ocean Ridge and the history of the crust and oceanic sedimentation in that general region (Sites 250, 251, 252).