As opposed to discontinuous seafloor dredging and coring, ophiolites and downhole geophysical measurements provide continuous sections along which high frequency accretion processes at mid-ocean ridges may be studied. A multidisciplinary study carried out on a volcanic section of the Semail ophiolite with MORB-like chemical composition reveals two main petrological and geochemical members. The boundary between the two is marked by the presence of a massive flow equating to the most primitive lava sampled, and across which significant changes are obtained. Petrophysical profiles are correlated to geochemical variations and provide thus a description of the magmatic activity through time. These temporal variations may be compared to those derived from crustal drilling and continuous logging measurements. ¿ 2000 American Geophysical Union