Do microplates in subduction zones leave a geological record?
Active microplate boundaries in ocean-continent subduction zones may induce deformation of the overlying plate and spatial or geochemical variations in the volcanic arc. We discuss two modern cases. The first is the South Gorda-Juan de Fuca plate boundary in the Cascadia subduction zone, where there...
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American Geophysical Union
1994
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ftcaltechauth:oai:authors.library.caltech.edu:46802 2023-05-15T14:04:55+02:00 Do microplates in subduction zones leave a geological record? Stock, Joann M. Lee, Jeffrey 1994-12 application/pdf https://authors.library.caltech.edu/46802/ https://authors.library.caltech.edu/46802/1/tect936.pdf https://resolver.caltech.edu/CaltechAUTHORS:20140703-094936902 en eng American Geophysical Union https://authors.library.caltech.edu/46802/1/tect936.pdf Stock, Joann M. and Lee, Jeffrey (1994) Do microplates in subduction zones leave a geological record? Tectonics, 13 (6). pp. 1472-1487. ISSN 0278-7407. doi:10.1029/94TC01808. https://resolver.caltech.edu/CaltechAUTHORS:20140703-094936902 <https://resolver.caltech.edu/CaltechAUTHORS:20140703-094936902> other Article PeerReviewed 1994 ftcaltechauth 2021-11-11T18:58:23Z Active microplate boundaries in ocean-continent subduction zones may induce deformation of the overlying plate and spatial or geochemical variations in the volcanic arc. We discuss two modern cases. The first is the South Gorda-Juan de Fuca plate boundary in the Cascadia subduction zone, where there is little or no effect on the overriding plate and the oceanic plate takes up much of the deformation. The second case is the Cocos-Rivera plate boundary in the Middle America trench, where the overlying Colima graben contains substantial deformation in a zone extending from the trench to the volcanic arc and the sub-duction-related volcanism is spatially and geochemically complex. We apply these observations to boundaries of the Arguello, Monterey, Guadalupe, and Magdalena microplates, which existed in the subduction zone west of Baja California at various times from 20 to 12.5 Ma. The past positions of these boundaries relative to Baja California are constrained by global plate reconstructions, closure of the Gulf of California, and an estimate of extension in the Mexican Basin and Range province. Existing regional mapping and our additional reconnaissance mapping show that Paleocene to Eocene fluvial and marine sedimentary rocks south of Ensenada along the western Baja California peninsula and eastward to the mid-Miocene volcanic arc are undeformed. Limited available data reveal no major spatial or geochemical variations in the mid-Miocene volcanic arc that might correlate with the past positions of the microplate boundaries. Thus these microplate boundaries had little to no effect on the overriding continental plate. The nature of Guadalupe and Magdalena interactions with North America may have been closer to the South Gorda-Juan de Fuca example, with possible internal deformation of the microplates. The Monterey and Arguello microplates may have behaved like the modern Explorer plate, with largely strike-slip motion relative to North America during their last stages of existence. Tectonic patterns similar to these examples may be expected from other plate boundaries where a plate is fragmenting as it enters a subduction zone (e.g., the Aluk plate in the trench beneath West Antarctica in early Tertiary time). Whether these microplates subsequently become attached to the overriding continental plate or to a larger oceanic plate and whether this causes deformation in the region of the former subduction zone may depend on the velocities of the nearby major plates and the relative orientations of the microplate boundaries. Article in Journal/Newspaper Antarc* Antarctica West Antarctica Caltech Authors (California Institute of Technology) Baja Rivera ENVELOPE(-61.017,-61.017,-64.267,-64.267) West Antarctica |
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Caltech Authors (California Institute of Technology) |
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ftcaltechauth |
language |
English |
description |
Active microplate boundaries in ocean-continent subduction zones may induce deformation of the overlying plate and spatial or geochemical variations in the volcanic arc. We discuss two modern cases. The first is the South Gorda-Juan de Fuca plate boundary in the Cascadia subduction zone, where there is little or no effect on the overriding plate and the oceanic plate takes up much of the deformation. The second case is the Cocos-Rivera plate boundary in the Middle America trench, where the overlying Colima graben contains substantial deformation in a zone extending from the trench to the volcanic arc and the sub-duction-related volcanism is spatially and geochemically complex. We apply these observations to boundaries of the Arguello, Monterey, Guadalupe, and Magdalena microplates, which existed in the subduction zone west of Baja California at various times from 20 to 12.5 Ma. The past positions of these boundaries relative to Baja California are constrained by global plate reconstructions, closure of the Gulf of California, and an estimate of extension in the Mexican Basin and Range province. Existing regional mapping and our additional reconnaissance mapping show that Paleocene to Eocene fluvial and marine sedimentary rocks south of Ensenada along the western Baja California peninsula and eastward to the mid-Miocene volcanic arc are undeformed. Limited available data reveal no major spatial or geochemical variations in the mid-Miocene volcanic arc that might correlate with the past positions of the microplate boundaries. Thus these microplate boundaries had little to no effect on the overriding continental plate. The nature of Guadalupe and Magdalena interactions with North America may have been closer to the South Gorda-Juan de Fuca example, with possible internal deformation of the microplates. The Monterey and Arguello microplates may have behaved like the modern Explorer plate, with largely strike-slip motion relative to North America during their last stages of existence. Tectonic patterns similar to these examples may be expected from other plate boundaries where a plate is fragmenting as it enters a subduction zone (e.g., the Aluk plate in the trench beneath West Antarctica in early Tertiary time). Whether these microplates subsequently become attached to the overriding continental plate or to a larger oceanic plate and whether this causes deformation in the region of the former subduction zone may depend on the velocities of the nearby major plates and the relative orientations of the microplate boundaries. |
format |
Article in Journal/Newspaper |
author |
Stock, Joann M. Lee, Jeffrey |
spellingShingle |
Stock, Joann M. Lee, Jeffrey Do microplates in subduction zones leave a geological record? |
author_facet |
Stock, Joann M. Lee, Jeffrey |
author_sort |
Stock, Joann M. |
title |
Do microplates in subduction zones leave a geological record? |
title_short |
Do microplates in subduction zones leave a geological record? |
title_full |
Do microplates in subduction zones leave a geological record? |
title_fullStr |
Do microplates in subduction zones leave a geological record? |
title_full_unstemmed |
Do microplates in subduction zones leave a geological record? |
title_sort |
do microplates in subduction zones leave a geological record? |
publisher |
American Geophysical Union |
publishDate |
1994 |
url |
https://authors.library.caltech.edu/46802/ https://authors.library.caltech.edu/46802/1/tect936.pdf https://resolver.caltech.edu/CaltechAUTHORS:20140703-094936902 |
long_lat |
ENVELOPE(-61.017,-61.017,-64.267,-64.267) |
geographic |
Baja Rivera West Antarctica |
geographic_facet |
Baja Rivera West Antarctica |
genre |
Antarc* Antarctica West Antarctica |
genre_facet |
Antarc* Antarctica West Antarctica |
op_relation |
https://authors.library.caltech.edu/46802/1/tect936.pdf Stock, Joann M. and Lee, Jeffrey (1994) Do microplates in subduction zones leave a geological record? Tectonics, 13 (6). pp. 1472-1487. ISSN 0278-7407. doi:10.1029/94TC01808. https://resolver.caltech.edu/CaltechAUTHORS:20140703-094936902 <https://resolver.caltech.edu/CaltechAUTHORS:20140703-094936902> |
op_rights |
other |
_version_ |
1766276376754651136 |