| Abstract: | The evolutionary history of the Pacific Ocean is reconstructed back to 60 m.y. B.P. based on the Hawaiian Island chain and Emperor seamounts, which join at an elbow to form the Hawaiian hotspot trace on the Pacific plate. This trace can be interpreted as a series of two rotations of the Pacific plate about the Hawaiian hotspot, presently located beneath Hawaii. Utilizing a pair of rotation poles in accordance with previously proposed models, the evolution can be described by the following: 1. (1) a rotation of 0.8°/m.y. about the Emperor pole of 17°N and 107°W from 60 to 42 m.y. B.P., and 2. (2) a rotation of 0.89°/m.y. about the Hawaiian pole of 69°N and 68°W from 42 m.y. B.P. to present. This model fits several constraints: 1. (1) the hotspot trace must continually pass through the hotspot, 2. (2) the elbow must reach the hotspot at 42 m.y. B.P, 3. (3) transform faults must lie on observed fracture zones, 4. (4) the first contact between the North American and Pacific plates must occur at about 30 m.y. B.P., and 5. (5) the motion between the North American and Pacific plates has been right-lateral from 30 m.y. B.P. to present. The overall fit of the digitized data of the hotspot trace to this model shows that it is possible to use the given poles for finite rotations and that the Kula-Pacific ridge is just now subducting. |
