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Rapid Early Cambrian rotation of Gondwana

Ross N. Mitchell, David A. D. Evans and Taylor M. Kilian
Rapid Early Cambrian rotation of Gondwana
Geology (Boulder) (August 2010) 38 (8): 755-758


Based on the history of Mesozoic-Cenozoic plate motions, as well as simple dynamical considerations, a "speed limit" for tectonic plates has been suggested at approximately 20 cm/yr. Previous paleomagnetic data from the Early Cambrian of Gondwana are conflicting but generally imply rapid motions approaching that limit. Herein we describe results from a continuous paleomagnetic sampling of Lower to Middle Cambrian strata from the Amadeus Basin, central Australia. We find characteristic remanence directions that show an approximately 60 degrees declination shift through the section. Assuming a tectonically assembled Gondwana supercontinent by Early Cambrian time, this large vertical-axis rotation of its Australian sector corresponds to an equally large translation across paleolatitudes for its Brazilian and West African sectors. Analysis of all high-quality paleomagnetic data from Gondwana both confirms and constrains the 60 degrees rotation to have occurred toward the end of Early Cambrian time, at rates exceeding 16 (super +12) / (sub -8) cm/yr. These observations suggest that either nonuniformitarian plate tectonics or an episode of rapid true polar wander occurred during the Cambrian "explosion" of animal life.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 38
Serial Issue: 8
Title: Rapid Early Cambrian rotation of Gondwana
Affiliation: Yale University, Department of Geology and Geophysics, New Haven, CT, United States
Pages: 755-758
Published: 201008
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 32
Accession Number: 2010-068276
Categories: StratigraphySolid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2010204
Illustration Description: illus. incl. strat. col., geol. sketch map
S23°48'00" - S23°48'00", E133°00'00" - E133°04'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201037
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