Birth of an intraoceanic spreading center

The Cocos-Nazca spreading center is one of the few examples of the formation of a spreading center by splitting of oceanic lithosphere. It was created when the Farallon plate broke up in the early Miocene following the collision of the Pacific-Farallon spreading center with the North American contin...

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Bibliographic Details
Published in:Geology (Boulder) 2008-10, Vol.36 (10), p.767-770
Main Authors: Barckhausen, Udo, Ranero, César R, Cande, Steven C, Engels, Martin, Weinrebe, Wilhelm
Format: Article
Language:English
Subjects:
applied (geophysical surveys & methods)
bathymetry
Central Pacific
Cocos Plate
crust
Farallon Plate
Geology
geophysical methods
geophysical profiles
geophysical surveys
Geophysics
Kinematics
lithosphere
magnetic methods
multichannel methods
Nazca Plate
ocean floors
oceanic crust
oceanic lithosphere
Oceans
Pacific Ocean
Pacific Plate
plate collision
Plate tectonics
sea-floor spreading
solid Earth (tectonophysics)
spreading centers
surveys
trenches
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Summary:The Cocos-Nazca spreading center is one of the few examples of the formation of a spreading center by splitting of oceanic lithosphere. It was created when the Farallon plate broke up in the early Miocene following the collision of the Pacific-Farallon spreading center with the North American continent. Much of the ancient Farallon plate corresponding to the area of opening is lost to subduction beneath Central America and South America, but new data from the conjugate area on the Pacific plate allow the first detailed reconstruction of the break-up process. The opening began after chron 7 (25 Ma) at a location of focused crustal extension caused by overlapping spreading centers that had evolved in response to a slight reorientation of a Pacific-Farallon ridge segment. Beginning at chron 6B (22.7 Ma), eastward progressing seafloor spreading started along an axis that most likely migrated toward the region of weak lithosphere created by the Galapagos hotspot. By chron 6 (19.5 Ma), plate splitting from the spreading center to the trench was complete, allowing the fully detached Cocos and Nazca plates to move independently. This kinematic change resulted in a significant ridge jump of the newly established Pacific-Nazca spreading center, a change in plate motion direction of the Nazca plate by 20° clockwise, and a large increase in Pacific-Cocos plate velocity in the middle Miocene.
ISSN:0091-7613
1943-2682
DOI:10.1130/G25056A.1