Abstract

Paleomagnetic data, normally presented in terms of paleopole positions, can be represented as paleolatitude and paleo-orientation calculated at an arbitrary reference site. In this form, the data can be used to derive the equation of motion of the region sampled, in terms of a particular model of the motion. For the plate tectonics model, the motion of the plates is sufficiently constrained that the position of the pole of opening can be derived directly from the paleomagnetic data. A mean North Atlantic pole of opening has been calculated from 38 paleomagnetic observations, ranging in age from 1.5 to 225 m.y., from the United States and southern Canada. The calculated pole of opening is near the Arctic coast of Siberia, in disagreement with a mean pole of opening near Iceland, inferred from sea-floor-spreading data. Sea-floor and paleomagnetic data considered together indicate that the North Atlantic system has moved northward relative to a fixed frame of reference aligned with the geomagnetic field. A westward component of movement may be present also but cannot be resolved.

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