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Was the Midcontinent Rift part of a successful seafloor‐spreading episode?
Author(s) -
Stein Carol A.,
Stein Seth,
Merino Miguel,
Randy Keller G.,
Flesch Lucy M.,
Jurdy Donna M.
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2013gl059176
Subject(s) - laurentia , geology , rift , precambrian , amazonian , seafloor spreading , craton , paleontology , rodinia , earth science , volcanism , massif , sill , geochemistry , amazon rainforest , paleozoic , tectonics , ecology , biology
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.