Late Cretaceous paleogeography of Wrangellia: Paleomagnetism of the MacColl Ridge Formation, southern Alaska, revisited
- 1Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, San Antonio, Texas 78238, USA
- 2Department of Geology, Bucknell University, Lewisburg, Pennsylvania 17837, USA
- 3Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907, USA
Abstract
Volcanic and sedimentary strata of the Late Cretaceous MacColl Ridge Formation were sampled and demagnetized to reevaluate the paleomagnetically derived paleolatitude of the allochthonous Wrangellia terrane. Characteristic directions from 15 sites representing ∼750 m of the MacColl Ridge Formation (80 Ma) reveal a reversed-polarity primary magnetization yielding a paleomagnetic pole at 126°E, 68°N, A95 = 9°. Comparison of this pole with the Late Cretaceous reference pole for North America indicates 15° ± 8° of latitudinal displacement (northward) and 33° ± 25° of counterclockwise rotation. In contrast to previously reported low paleolatitudes (32° ± 9°N) for the MacColl Ridge Formation, these new results place the Wrangellia terrane at a moderate paleolatitude (53° ± 8°N) in the Late Cretaceous.
Footnotes
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↵GSA Data Repository item 2001105, Appendix A, Methods and results, is available on request from Documents Secretary, GSA, P.O Box 9140, Boulder, CO 80301-9140, editing@geosociety.org, or at www.geosociety.org/pubs/ft2001.htm.
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- Accepted June 21, 2001.
- Received January 18, 2001.
- Revision received June 19, 2001.
- Geological Society of America
