Figure F2. Seismic profiles indicate the subsurface structure of the central dome and eastern block of Atlantis Massif. A. Deep source refraction (NOBEL Line 9) recorded by an ocean bottom hydrophone shows high velocity arrivals (8 km/s) at very short range. B. Velocity gradient at Atlantis Massif; gradient is similar to that determined near Ocean Drilling Program (ODP) Hole 920, where serpentinized peridotite was recovered. The gradient near Hole 735B, where only gabbro has been recovered, is not as great. MARK = Mid-Atlantic Ridge south of the Kane Fracture Zone, MAR = Mid-Atlantic Ridge, SWIR = Southwest Indian Ridge. C. A portion of Multichannel seismic (MCS) Line Meg10 across the Central Dome. D. MCS Line Meg4, along the strike of Atlantis Massif. MCS data were collected by the Ewing (EW-0102) in 2001 using a 10-gun array with 3100 in³ (51 L) capacity. Shot spacing was 37.5 m. Canales et al. (2004) processed the data by common midpoint (CMP) gathers, deconvolution, normal moveout correction, dip moveout correction, and stacking. In addition, record section in D has been time migrated.