The Evolution of the Indian Ocean Triple Junction and the Finite Rotation Problem.

• Main Author: Tapscott,Christopher Robert
• Other Authors: WOODS HOLE OCEANOGRAPHIC INSTITUTION MASS
• Format: Text
• Language: English
• Published: 1980
• Subjects: Physical and Dynamic Oceanography; Geology; Geochemistry and Mineralogy; *OCEAN RIDGES; *SEAFLOOR SPREADING; *TECTONICS; VELOCITY; INDIA; THESES; CONTINENTAL DRIFT; PLATES; EVOLUTION(GENERAL); JUNCTIONS; AFRICA; ROTATION; RIGIDITY; INDIAN OCEAN; OCEANIC CRUST; ANTARCTIC REGIONS; GREENLAND; MAGNETIC ANOMALIES; LITHOSPHERE; LABRADOR SEA; Plate tectonics; Triple junctions; Southwest Indian Ridge; WUNR083004; Antarctic; Greenland; Indian; Antarc*; Antarctica; Labrador Sea
• Online Access: http://www.dtic.mil/docs/citations/ADA089103; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA089103

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). Prepared in cooperation with Massachusetts Inst. of Tech., Cambridge. Dept. of Earth and Planetary Sciences, Contract N00014-75-C-0291.