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{{short description|A small fully subducted tectonic plate}} |
{{short description|A small fully subducted tectonic plate}} |
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Located in the western Pacific Ocean near Indonesia, the '''Molucca Sea Plate''' has been classified by scientists as a fully subducted microplate that is part of the Molucca Sea Collision Complex. The Molucca Sea Plate represents the only known example of [[divergent double subduction]] (DDS), which describes the subduction on both sides of a single oceanic plate.<ref name=":0">{{Cite journal|last=Zhang|first=Qingwen|last2=Guo|first2=Feng|last3=Zhao|first3=Liang|last4=Wu|first4=Yangming|date=2017 |
Located in the western Pacific Ocean near Indonesia, the '''Molucca Sea Plate''' has been classified by scientists as a fully subducted microplate that is part of the Molucca Sea Collision Complex. The Molucca Sea Plate represents the only known example of [[divergent double subduction]] (DDS), which describes the subduction on both sides of a single oceanic plate.<ref name=":0">{{Cite journal|last=Zhang|first=Qingwen|last2=Guo|first2=Feng|last3=Zhao|first3=Liang|last4=Wu|first4=Yangming|date=May 2017|title=Geodynamics of divergent double subduction: 3-D numerical modeling of a Cenozoic example in the Molucca Sea region, Indonesia|journal=Journal of Geophysical Research: Solid Earth|volume=122|issue=5|pages=3977–3998|doi=10.1002/2017jb013991|issn=2169-9313}}</ref> |
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[[File:MoluccaSeaCollisionZone.png|thumb|460x460px|Molucca Sea Collision Zone modified by Zhang et al.<ref |
[[File:MoluccaSeaCollisionZone.png|thumb|460x460px|Molucca Sea Collision Zone modified by Zhang et al.<ref name=":0"/> using GeoMapApp]] |
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== Tectonic setting == |
== Tectonic setting == |
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The Molucca Sea Plate is one of many tectonic features that compose the [[Molucca Sea Collision Zone|Molucca Sea Collision Complex]], which refers to the tectonic relationship of the [[Sangihe Plate]], [[Halmahera Plate]], and the Molucca Sea Plate, in addition to the volcanic [[Halmahera Arc|Halmahera]] and [[Sangihe Plate|Sangihe]] Arcs. The southeast moving [[Sangihe Plate]] is situated along the western boundary of the Molucca Sea Plate. The northwest moving [[Halmahera Plate]] is situated along the eastern boundary of the Molucca Sea Plate. In the western [[Pacific Ocean]], the [[Molucca Sea]] is bordered by the Indonesian Islands of Celebes ([[Sulawesi]]) to the west, [[Halmahera]] to the east, and the Sula Islands to the south. The Molucca Sea borders the [[Banda Sea]] to the south and the [[Celebes Sea]] to the west. To the north is the [[Philippine Sea]] and to the east is the [[Halmahera Sea]]. Situated south of [[Mindanao]], the Molucca Sea is a narrow basin underlined by a north‐south [[Ophiolite|ophiolitic]] ridge, which uplifts the central region of the basin.<ref name=":1">{{Cite journal|last=Silver|first=Eli A.|last2=Moore|first2=J. Casey|date=1978-04-10|title=The Molucca Sea Collision Zone, Indonesia|journal=Journal of Geophysical Research: Solid Earth |
The Molucca Sea Plate is one of many tectonic features that compose the [[Molucca Sea Collision Zone|Molucca Sea Collision Complex]], which refers to the tectonic relationship of the [[Sangihe Plate]], [[Halmahera Plate]], and the Molucca Sea Plate, in addition to the volcanic [[Halmahera Arc|Halmahera]] and [[Sangihe Plate|Sangihe]] Arcs. The southeast moving [[Sangihe Plate]] is situated along the western boundary of the Molucca Sea Plate. The northwest moving [[Halmahera Plate]] is situated along the eastern boundary of the Molucca Sea Plate. In the western [[Pacific Ocean]], the [[Molucca Sea]] is bordered by the Indonesian Islands of Celebes ([[Sulawesi]]) to the west, [[Halmahera]] to the east, and the Sula Islands to the south. The Molucca Sea borders the [[Banda Sea]] to the south and the [[Celebes Sea]] to the west. To the north is the [[Philippine Sea]] and to the east is the [[Halmahera Sea]]. Situated south of [[Mindanao]], the Molucca Sea is a narrow basin underlined by a north‐south [[Ophiolite|ophiolitic]] ridge, which uplifts the central region of the basin.<ref name=":1">{{Cite journal|last=Silver|first=Eli A.|last2=Moore|first2=J. Casey|date=1978-04-10|title=The Molucca Sea Collision Zone, Indonesia|journal=Journal of Geophysical Research: Solid Earth|volume=83|issue=B4|pages=1681–1691|doi=10.1029/jb083ib04p01681|issn=0148-0227}}</ref> |
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== Plate mechanics == |
== Plate mechanics == |
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[[File:CrossSection.png|thumb|460x460px|Cross Section of Molucca Sea Collision Zone modified by Zhang et al.<ref |
[[File:CrossSection.png|thumb|460x460px|Cross Section of Molucca Sea Collision Zone modified by Zhang et al.<ref name=":0"/>]] |
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While the scientific community has not come to a consensus as to when the Molucca Sea Plate became fully subducted, the dominant theory is that the Molucca Sea Plate has been completely subducted beneath the overriding [[Halmahera Plate|Halmahera]] and [[Sangihe Plate |
While the scientific community has not come to a consensus as to when the Molucca Sea Plate became fully subducted, the dominant theory is that the Molucca Sea Plate has been completely subducted beneath the overriding [[Halmahera Plate|Halmahera]] and [[Sangihe Plate]]s.<ref name=":0" /> When actively subducting, the crustal collision of the Molucca Sea Plate was formed by surface intersection of “oppositely dipping [[Wadati–Benioff zone|Benioff zones]]” (also known as divergent double subduction) which results in the [[Sangihe Plate|Sangihe]] and Halmahera [[volcanic arc]]s.<ref name=":1" /> The force exerted by the thick overlying collision complex of the Halmahera and Sangihe Plates effectively depressed the crust of the Molucca Sea Plate.<ref>{{Cite journal|last=McCaffre, Silver, Raitt|first=Robert, Eli, Russell|date=1980|title=Crustal Structure of the Molucca Sea Collision Zone,Indonesia|url=http://web.pdx.edu/~mccaf/pubs/mccaffrey_mol_sea_agu_1980.pdf|journal=Geophysical Monograph 23|volume=|pages=|via=}}</ref> The plate itself features an asymmetrical morphology, configured in an inverted U-shape. The arc-arc collision zone of the Molucca Sea Plate is characterized as a thick, low velocity layer, which is highly variable in density.<ref name=":0" /><ref>{{Cite book|title=The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands|last=McCaffrey|first=Robert|last2=Silver|first2=Eli A.|last3=Raitt|first3=Russell W.|date=1980|publisher=American Geophysical Union|isbn=978-0875900230|location=Washington, D. C.|pages=161–177|doi=10.1029/gm023p0161}}</ref> The variable in density of the Molucca Sea Plate led to different subduction velocities on the two sides.<ref name=":0" /> [[Divergent double subduction|Divergent Double Subduction]] may facilitate various tectonic processes, including closure of ocean basins, [[Accretion (geology)|accretion]] and amalgamation of volcanic arcs, and growth of continents.<ref name=":0" /> |
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== Earthquakes == |
== Earthquakes == |
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[[File:Divergent Double Subduction Zone.png|thumb|460x460px|(Asymmetric) Divergent Double Subduction Zone modified by Zhao et al.<ref |
[[File:Divergent Double Subduction Zone.png|thumb|460x460px|(Asymmetric) Divergent Double Subduction Zone modified by Zhao et al.<ref name=":0"/>]] |
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Historically, the Molucca Sea Plate has experienced hundreds of earthquakes ranging in magnitude.<ref |
Historically, the Molucca Sea Plate has experienced hundreds of earthquakes ranging in magnitude.<ref name=":1"/> The most recent large earthquake occurred on January 2017 when a 7.3 magnitude earthquake deep beneath the [[Celebes Sea]], which the USGS attributed to the “''deep reverse faulting within the inclined seismic zone defining the deep limit of the Molucca Sea microplate beneath the Celebes Sea Basin.''”<ref>{{Cite news|url=https://www.decodedscience.org/philippines-iran-alaska-far-north-earthquakes-5-11-january-2017/60479|title=Philippines, Iran, Alaska (and the Far North): Earthquakes 5-11 January 2017|date=2017-01-11|work=Decoded Science|access-date=2018-06-03}}</ref> |
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== Geology == |
== Geology == |
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The geologic characteristics displayed on the surrounding islands provide insight regarding the complex plate movement of the [[Divergent double subduction|divergent double subducting]] plate. Detached [[Ophiolite|ophiolitic]] series and thick [[Mélange|melanges]] are overlain by [[forearc]] deposits; subduction-driven east-west shortening of the Snellius Plateau caused the thrust [[Mélange|melanges]] to reactivate and deform the [[forearc]] series.<ref>{{Cite journal|last=Bader|first=Anne Gaëlle|last2=Pubellier|first2=Manuel|date=2008-07-18|title=Forearc deformation and tectonic significance of the ultramafic Molucca central ridge, Talaud islands (Indonesia)|journal=Island Arc |
The geologic characteristics displayed on the surrounding islands provide insight regarding the complex plate movement of the [[Divergent double subduction|divergent double subducting]] plate. Detached [[Ophiolite|ophiolitic]] series and thick [[Mélange|melanges]] are overlain by [[forearc]] deposits; subduction-driven east-west shortening of the Snellius Plateau caused the thrust [[Mélange|melanges]] to reactivate and deform the [[forearc]] series.<ref>{{Cite journal|last=Bader|first=Anne Gaëlle|last2=Pubellier|first2=Manuel|date=2008-07-18|title=Forearc deformation and tectonic significance of the ultramafic Molucca central ridge, Talaud islands (Indonesia)|journal=Island Arc|volume=9|issue=4|pages=653–663|doi=10.1111/j.1440-1738.2000.00309.x|issn=1038-4871}}</ref> Exposed [[Ophiolite|ophiolitic]] rocks can be found on the islands of the submarine Talaud-Mayu Ridge, which bisects the arc-arc collision zone of the Molucca Sea Plate; these [[ophiolite]]s provide insight regarding the relationship between earthquakes and uplift surrounding the plate.<ref>{{Cite journal|last=McCaffrey|first=Robert|date=April 1991|title=Earthquakes and ophiolite emplacement in the Molucca Sea Collision Zone, Indonesia|journal=Tectonics|volume=10|issue=2|pages=433–453|doi=10.1029/90tc02553|issn=0278-7407}}</ref> |
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== See also == |
== See also == |
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[[Category:Geology of Indonesia]] |
[[Category:Geology of Indonesia]] |
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[[Category:Molucca Sea]] |
[[Category:Molucca Sea]] |
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{{tectonics-stub}} |
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Revision as of 16:11, 16 January 2019
Located in the western Pacific Ocean near Indonesia, the Molucca Sea Plate has been classified by scientists as a fully subducted microplate that is part of the Molucca Sea Collision Complex. The Molucca Sea Plate represents the only known example of divergent double subduction (DDS), which describes the subduction on both sides of a single oceanic plate.[1]
Tectonic setting
The Molucca Sea Plate is one of many tectonic features that compose the Molucca Sea Collision Complex, which refers to the tectonic relationship of the Sangihe Plate, Halmahera Plate, and the Molucca Sea Plate, in addition to the volcanic Halmahera and Sangihe Arcs. The southeast moving Sangihe Plate is situated along the western boundary of the Molucca Sea Plate. The northwest moving Halmahera Plate is situated along the eastern boundary of the Molucca Sea Plate. In the western Pacific Ocean, the Molucca Sea is bordered by the Indonesian Islands of Celebes (Sulawesi) to the west, Halmahera to the east, and the Sula Islands to the south. The Molucca Sea borders the Banda Sea to the south and the Celebes Sea to the west. To the north is the Philippine Sea and to the east is the Halmahera Sea. Situated south of Mindanao, the Molucca Sea is a narrow basin underlined by a north‐south ophiolitic ridge, which uplifts the central region of the basin.[2]
Plate mechanics
While the scientific community has not come to a consensus as to when the Molucca Sea Plate became fully subducted, the dominant theory is that the Molucca Sea Plate has been completely subducted beneath the overriding Halmahera and Sangihe Plates.[1] When actively subducting, the crustal collision of the Molucca Sea Plate was formed by surface intersection of “oppositely dipping Benioff zones” (also known as divergent double subduction) which results in the Sangihe and Halmahera volcanic arcs.[2] The force exerted by the thick overlying collision complex of the Halmahera and Sangihe Plates effectively depressed the crust of the Molucca Sea Plate.[3] The plate itself features an asymmetrical morphology, configured in an inverted U-shape. The arc-arc collision zone of the Molucca Sea Plate is characterized as a thick, low velocity layer, which is highly variable in density.[1][4] The variable in density of the Molucca Sea Plate led to different subduction velocities on the two sides.[1] Divergent Double Subduction may facilitate various tectonic processes, including closure of ocean basins, accretion and amalgamation of volcanic arcs, and growth of continents.[1]
Earthquakes
Historically, the Molucca Sea Plate has experienced hundreds of earthquakes ranging in magnitude.[2] The most recent large earthquake occurred on January 2017 when a 7.3 magnitude earthquake deep beneath the Celebes Sea, which the USGS attributed to the “deep reverse faulting within the inclined seismic zone defining the deep limit of the Molucca Sea microplate beneath the Celebes Sea Basin.”[5]
Geology
The geologic characteristics displayed on the surrounding islands provide insight regarding the complex plate movement of the divergent double subducting plate. Detached ophiolitic series and thick melanges are overlain by forearc deposits; subduction-driven east-west shortening of the Snellius Plateau caused the thrust melanges to reactivate and deform the forearc series.[6] Exposed ophiolitic rocks can be found on the islands of the submarine Talaud-Mayu Ridge, which bisects the arc-arc collision zone of the Molucca Sea Plate; these ophiolites provide insight regarding the relationship between earthquakes and uplift surrounding the plate.[7]
See also
References
- ^ a b c d e f g h Zhang, Qingwen; Guo, Feng; Zhao, Liang; Wu, Yangming (May 2017). "Geodynamics of divergent double subduction: 3-D numerical modeling of a Cenozoic example in the Molucca Sea region, Indonesia". Journal of Geophysical Research: Solid Earth. 122 (5): 3977–3998. doi:10.1002/2017jb013991. ISSN 2169-9313.
- ^ a b c Silver, Eli A.; Moore, J. Casey (1978-04-10). "The Molucca Sea Collision Zone, Indonesia". Journal of Geophysical Research: Solid Earth. 83 (B4): 1681–1691. doi:10.1029/jb083ib04p01681. ISSN 0148-0227.
- ^ McCaffre, Silver, Raitt, Robert, Eli, Russell (1980). "Crustal Structure of the Molucca Sea Collision Zone,Indonesia" (PDF). Geophysical Monograph 23.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ McCaffrey, Robert; Silver, Eli A.; Raitt, Russell W. (1980). The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands. Washington, D. C.: American Geophysical Union. pp. 161–177. doi:10.1029/gm023p0161. ISBN 978-0875900230.
- ^ "Philippines, Iran, Alaska (and the Far North): Earthquakes 5-11 January 2017". Decoded Science. 2017-01-11. Retrieved 2018-06-03.
- ^ Bader, Anne Gaëlle; Pubellier, Manuel (2008-07-18). "Forearc deformation and tectonic significance of the ultramafic Molucca central ridge, Talaud islands (Indonesia)". Island Arc. 9 (4): 653–663. doi:10.1111/j.1440-1738.2000.00309.x. ISSN 1038-4871.
- ^ McCaffrey, Robert (April 1991). "Earthquakes and ophiolite emplacement in the Molucca Sea Collision Zone, Indonesia". Tectonics. 10 (2): 433–453. doi:10.1029/90tc02553. ISSN 0278-7407.
