Between March and May 1998 the British Antarctic Survey ship James Clark Ross carried out a detailed geophysical survey of Atlantis Bank which is adjacent to the Atlantis II Fracture Zone in the Indian Ocean. Atlantis Bank is the site of Ocean Drilling Program Hole 735B which was drilled in 198? during Leg 118 and was recently reentered on Leg 176 and drilled to 1500 m below the seafloor. The hole encompassed entirely lower crustal rocks i.e. gabbro. This is remarkable because the magnetic anomaly stripes continue across the Atlantis Bank even though the upper crustal lavas which are thought to be the main source of the magnetic anomaly stripes are completely absent. We first undertook a remotely operated vehicle (ROV) survey using the Canadian ROV ROPOS. Magnetic field measurements show a consistent pattern of magnetic anomalies across the Atlantis Bank.

Published magnetic results

Crustal magnetization and crustal accretion at the southwest Indian Ridge near the Atlantis II fracture zone, 0-25 Ma, A. Hosford, M. Tivey, T. Matsumoto, H. Dick, H. Schouten and H. Kinoshita, Journal of Geophysical Research, 108, B3, 2169, 10:1029/2001JB000604, 2003.

Magnetic polarity structure of the lower oceanic crust, S. Allerton and M. A. Tivey, Geophysical Research Letters, 28, 3, 423-426, 2001.

Provisional Figures