Satellite magnetic constraints on the Phanerozoic dynamics of the continents
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Date
1985
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Publisher
The Ohio State University
Abstract
Differentially reduced to pole MAGSAT magnetic anomalies, which directly overlie their crustal sources, have been superimposed on paleocontinental world maps ranging from 560 Ma to 220 Ma. Generally cratons and shields are characterized by positive magnetic anomalies, while Mesozoic aged or younger rifts are characterized by negative magnetic anomalies. Many cratons dissected by rifting show a correlation of magnetic anomaly sources across the rifted margin. Using cross-cutting relationships, several rift-dissected anomalies can be given a minimum age, while many magnetic negatives can be dated as rift-contemporaneous. For example, the Bangui magnetic anomaly over west-central Africa and the magnetic high overlying the Sao Luiz Craton and Central Brazilian Shield of central South America correlate on Gondwanaland reconstructions, suggesting that these anomalies may pre-date the break-up of Gondwanaland. The negative anomalies centered over the Takatu rift and the Amazon River rift of South America are dated as rift-contemporaneous. In most cases, MAGSAT magnetic anomalies verify the accuracy of Paleozoic continental reconstructions.