Ophiolite emplacement on to continental margins

Abstract

RECENT work on west Newfoundland ophiolites supports Elliott's1 contention that the mechanics of emplacement of oceanic crust and upper mantle on to continental margins (‘obduction’) is no different from the emplacement of thrust sheets in any foreland thrust belt. Evidence to this effect comes from the presence of minor structures found along the thrust fault surfaces separating the various structural slices, as well as from other related minor structures—hitherto unrecorded in ophiolite suites—that have been found within the thrust sheets themselves. These reveal a very specific kind of information about the mechanics of ophiolite transportation and, without reference to the forces causing emplacement, they imply that many of the processes involved in the motion of ophiolite thrust sheets are equivalent to those typical of foreland thrust belts—due consideration being given to basic differences in the material properties of the rocks involved.