Mantle flow at oceanic spreading centers: Models derived from ophiolites

摘要: Abstract The internal structures of eleven ophiolite complexes have been structurally investigated. attitude the foliation and lineation in peridotites is related to asthenospheric flow uppermost mantle at an oceanic spreading center. From orientation these with respect paleohorizontal plane, two situations are distinguished. horizontally asthenosphere illustrated by Table Mountain massif (Newfoundland) characterized by: 1. (a) homogeneous, regular sub-horizontal plastic pattern: over large distances; 2. (b) flat paleo Mono absence scale folding; 3. (c) rare economical chromite deposits depleted mantle. diapirically Acoje type (Philippines) displays: inhomogeneous sub-vertical pattern; b) deformed Moho folds; (c)important less mantle, presumably due secondary magmatic impregnation. This leads Vogt's model beneath ridge (the direction which being equated dike swarm). In this derived from one following way. vertical diapir center diverges horizontally, every including that parallel ridge. At about 50 km becomes progressively perpendicular damming effect transform faults. An important consequence expected preferentially diapiric because precipitated pristine magma.