GEOLOGICAL STRUCTURE OF THE STRAKHOV FRAC TURE-ZONE (EQUATORIAL SEGMENT OF THE MID-ATLANTIC RIDGE)

Geological-geophysical data, collected in 1989 - 1991 in 7, 11 and 12 cruises of the R/V ''Akademik Nikolai Strakhov'' within the internatio nal project EQUARIDGE in the region of the Strakhov fracture zone (4 d egrees N) are presented. The trough of the fracture is interpreted as an open fissure, a graben produced by stretching along the axis of the Mid-Atlantic ridge. Basement rocks proved to be truly oceanic tholeii tic basalts only in the narrow (60 miles) axial rift zone, while rocks not typical to the ocean were met on the eastern and western flank pl ateaus. It allows to suppose that a relict pre-upperurassic reworked b asement of a continental type may be present in this segment under the flank plateaus. The data presented in this paper coincide with a hypo thesis by E. Bonatti about a non-spreading nature of oceanic basement in the equatorial segment of the Mid-Atlantic ridge and Strakhov fract ure zone.