Was the Midcontinent Rift part of a successful seafloor-spreading episode?

The ~1.1 Ga Midcontinent Rift (MCR), the 3000 km long largely buried feature causing the largest gravity and magnetic anomaly within the North American craton, is traditionally considered a failed rift formed by isolated midplate volcanism and extension. We propose instead that the MCR formed as par...

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Bibliographic Details
Published in:Geophysical research letters 2014-03, Vol.41 (5), p.1465-1470
Main Authors: Stein, Carol A., Stein, Seth, Merino, Miguel, Randy Keller, G., Flesch, Lucy M., Jurdy, Donna M.
Format: Article
Language:English
Subjects:
Amazonia
Americas
apparent polar wander path
continental extension
Continents
Cratons
Cusps
Gravitation
Gravity
Identification
Laurentia
Magma
Magnetic anomalies
Mid-Continent rift
Northwest
Ocean floor
Polar wandering
Precambrian
Rifting
Rocks
Seafloor spreading
Spreading
Volcanic activity
Volcanic rocks
Volcanism
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Summary:The ~1.1 Ga Midcontinent Rift (MCR), the 3000 km long largely buried feature causing the largest gravity and magnetic anomaly within the North American craton, is traditionally considered a failed rift formed by isolated midplate volcanism and extension. We propose instead that the MCR formed as part of the rifting of Amazonia (Precambrian northeast South America) from Laurentia (Precambrian North America) and became inactive once seafloor spreading was established. A cusp in Laurentia's apparent polar wander path near the onset of MCR volcanism, recorded by the MCR's volcanic rocks, likely reflects the rifting. This scenario is suggested by analogy with younger rifts elsewhere and consistent with the MCR's extension to northwest Alabama along the East Continent Gravity High, southern Appalachian rocks having Amazonian affinities, and recent identification of contemporaneous large igneous provinces in Amazonia. Key Points ~1.1Ga Mid‐Continent Rift (MCR) formed during rifting of Amazonia from Laurentia MCR continues to northwest Alabama along East Continent Gravity High Apparent polar wander path's cusp reflects rifting event
ISSN:0094-8276
1944-8007
DOI:10.1002/2013GL059176