Preliminary paleomagnetic results from Jurassic rocks of the Santa Marta Massif Colombia
Published:January 01, 1984
William D. MacDonald, Neil D. Opdyke, 1984. "Preliminary paleomagnetic results from Jurassic rocks of the Santa Marta Massif Colombia", The Caribbean-South American Plate Boundary and Regional Tectonics, William E. Bonini, Robert B. Hargraves, Reginald Shagam
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From the Sierra Nevada of Santa Marta at the northern terminus of the Andes, preliminary paleomagnetic results from ten sites in two formations characteristically have stable directions with northerly declinations and moderate positive inclinations. Most site mean directions are close in attitude to the present Earth's field and are not indicative of large tectonic rotations. An antipodally reversed direction is obtained at one site by thermal demagnetization, suggesting magnetization in an ancient paleofield nearly coaxial with the present field. Few cratonic Jurassic directions have been reported from South America, but at least one such study shows Jurassic paleofield directions close to the present field directions. In defining the Mesozoic polar wander path for South America, distinguishing Jurassic from present field directions will be a continuing challenge.