This paper presents the results of detailed mapping of high-temperature flow structures in the mantle and crust of two massifs of the Oman ophiolite. In these massifs, the dominant structures, including large-scale folds, shear zones, and fractures, were generated at elevated temperatures and are ascribed to the ridge or ridge environment activity; this means that the structural maps presented can be viewed as those of partly dissected ridge segments. It has been possible in the two massifs to locate the paleoaxis of the oceanic ridge which created this crust. This location, which is constrained by several independent tests, is a prerequisite to reconstruct the structure and to investigate the dynamics of a fast spreading ridge. In the Nakhl-Rustaq massif, high temperature tectonic activity at the ridge rotated the Moho toward a vertical attitude and folded the layered gabbros on the scale of several hundred meters. This tectonism is attributed to a propagating ridge deforming a slightly older lithosphere. The propagating ridge segment extends in the field from a diapir area to a domain located along strike some 20 km away, where the sheeted dike complex roots directly in the mantle, without layered gabbros in between. The diapir area represents the mantle feeder for the ridge segment, and the rooted dikes represent the propagating tip. Other results include the detailed mapping of two mantle diapirs and of the diverging mantle flow issued from them. Magma chambers are centered over diapirs and are tent-shaped, in accord with our previous models. ¿ American Geophysical Union 1995