The Evolution of the Indian Ocean Triple Junction and the Finite Rotation Problem.
WOODS HOLE OCEANOGRAPHIC INSTITUTION MASS
Pagination or Media Count:
The three papers of this thesis demonstrate that studies of the stability and evolution of triple junctions and of the finite rotations of systems of three plates can yield significantly more accurate tectonic histories than can studies of relative motions between two plates alone. Topographic and magnetic investigation of the Southwest Indian Ridge and reconstruction of the plate system of the Indian Ocean shows that both Africa and Antarctica are rigid plates and their pole of relative rotation has remained fixed near 8 deg N, 42 deg W since the Eocene. A detailed survey of the Indian Ocean triple junction reveals that the Indian Ocean plate motions have remained constant since 10 Ma. Stability conditions of the junctions show that the general morphology of the Southwest Indian Ridge results from the evolution of the Indian Ocean triple junction. A method is presented for determining the finite rotations best reconstructing the past relative positions of three plates around a triple junction. The method is illustrated by reconstructions of the plates around the Labrador Sea triple junction at the times of anomalies 24 56 Ma and 21 50 Ma.
- Physical and Dynamic Oceanography
- Geology, Geochemistry and Mineralogy