Subduction polarity reversal: Difference between revisions

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Revision as of 03:17, 9 January 2019

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[[File:Subduction_polarity_reversal.svg|thumb|471x471px|The concept of flipping of subduction polarity]]

'''Subduction polarity reversal''' is a geologic process in which two converging plates switch roles: The over-lying plate becomes the down-going plate, and vice versa. There are two basic units which make up a [[Subduction|subduction zone]]. This consists of an overriding plate and the subduction plate.<ref name=":142">{{Cite book|url=https://www.springer.com/gp/book/9783540885573|title=Arc-Continent Collision {{!}} Dennis Brown {{!}} Springer|isbn=9783540885573|publisher=Springer|year=2011|series=Frontiers in Earth Sciences}}</ref> Two plates move towards each other due to [[Tectonics|tectonic forces]].<ref name=":142" /> The overriding plate will be on the top of the subducting plate.<ref name=":142" /> This type of tectonic interaction is found at many [[Plate tectonics|plate boundaries]].<ref name=":142" />

However, some geologists propose that the roles of the overriding plate and subducting plate do not remain the same indefinitely.<ref name=":113">{{Cite journal|last=Chemenda|first=A. I.|last2=Yang|first2=R. -K.|last3=Stephan|first3=J. -F.|last4=Konstantinovskaya|first4=E. A.|last5=Ivanov|first5=G. M.|date=2001-04-10|title=New results from physical modelling of arc–continent collision in Taiwan: evolutionary model|url=http://www.sciencedirect.com/science/article/pii/S0040195100002730|journal=Tectonophysics|volume=333|issue=1–2|pages=159–178|doi=10.1016/S0040-1951(00)00273-0|bibcode=2001Tectp.333..159C}}</ref> Their roles will swap, which means the plate originally subducting beneath will become the overriding plate.<ref name=":113" /> This phenomenon is called '''subduction switch''',<ref>{{cite journal|last1=Willett|first1=S. D.|last2=Beaumont|first2=C.|title=Subduction of Asian lithospheric mantle beneath Tibet inferredfrom models of continental collision|journal=Nature|date=1994-06-23|volume=369|issue=6482|pages=642–645|doi=10.1038/369642a0|bibcode=1994Natur.369..642W}}</ref> '''the flipping of subduction polarity'''<ref name=":132222">{{Cite journal|last=Teng|first=Louis S.|last2=Lee|first2=C. T.|last3=Tsai|first3=Y. B.|last4=Hsiao|first4=Li-Yuan|date=2000-02-01|title=Slab breakoff as a mechanism for flipping of subduction polarity in Taiwan|url=http://geology.gsapubs.org/content/28/2/155|journal=Geology|language=en|volume=28|issue=2|pages=155–158|doi=10.1130/0091-7613(2000)28<155:sbaamf>2.0.co;2|issn=0091-7613}}</ref> or '''subduction polarity reversal'''.<ref name=":113" />

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Examples of subduction systems with subduction polarity reversal are:

* [[Caledonian orogeny|Caledonides]], Ireland<ref>{{Cite book|url=https://link.springer.com/chapter/10.1007/978-3-540-88558-0_13|title=Arc-Continent Collision|last=Ryan|first=P. D.|last2=Dewey|first2=J. F.|date=2011-01-01|publisher=Springer Berlin Heidelberg|isbn=9783540885573|series=Frontiers in Earth Sciences|pages=373–401|language=en|doi=10.1007/978-3-540-88558-0_13}}</ref>

* [[Apennine Mountains|Alps-Apennines]], Italy<ref name=":43">{{Cite journal|last=Molli|first=G.|last2=Malavieille|first2=J.|date=2010-09-28|title=Orogenic processes and the Corsica/Apennines geodynamic evolution: insights from Taiwan|url=https://link.springer.com/article/10.1007/s00531-010-0598-y|journal=International Journal of Earth Sciences|language=en|volume=100|issue=5|pages=1207–1224|doi=10.1007/s00531-010-0598-y|issn=1437-3254|bibcode=2011IJEaS.100.1207M}}</ref><ref name=":43"/>

* [[Kamchatka Peninsula|Kamchatka]], Russia<ref name=":54">{{Cite journal|last=Konstantinovskaia|first=E. A|date=2001-04-10|title=Arc–continent collision and subduction reversal in the Cenozoic evolution of the Northwest Pacific: an example from Kamchatka (NE Russia)|url=http://www.sciencedirect.com/science/article/pii/S0040195100002687|journal=Tectonophysics|volume=333|issue=1–2|pages=75–94|doi=10.1016/S0040-1951(00)00268-7|bibcode=2001Tectp.333...75K}}</ref>

* [[Wetar]], eastern Indonesia<ref>{{Cite book|url=https://books.google.com/?id=bKg_AAAAIAAJ&pg=PR1&dq=Tectonics+of+the+Indonesian+region#v=onepage&q=Tectonics%20of%20the%20Indonesian%20region&f=false|title=Tectonics of the Indonesian region|last=Hamilton|first=Warren Bell|last2=Pertambangan|first2=Indonesia Departemen|last3=Development|first3=United States Agency for International|date=1979-01-01|publisher=U.S. Govt. Print. Off.|language=en}}</ref>

* [[Timor]], east Savu Sea<ref>{{Cite journal|last=McCaffrey|first=Robert|last2=Molnar|first2=Peter|last3=Roecker|first3=Steven W.|last4=Joyodiwiryo|first4=Yoko S.|date=1985-05-10|title=Microearthquake seismicity and fault plane solutions related to arc-continent collision in the Eastern Sunda Arc, Indonesia|url=http://onlinelibrary.wiley.com/doi/10.1029/JB090iB06p04511/abstract|journal=Journal of Geophysical Research: Solid Earth|language=en|volume=90|issue=B6|pages=4511–4528|doi=10.1029/JB090iB06p04511|issn=2156-2202|bibcode=1985JGR....90.4511M}}</ref>

* [[Mediterranean Sea|Mediterranean]]<ref>{{Cite journal|title=Structure and dynamics of subducted lithosphere in the Mediterranean region|url=http://cat.inist.fr/?aModele=afficheN&cpsidt=4305568|journal=Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen|volume=95|issue=3|issn=0924-8323}}</ref>

* [[Geology of Taiwan|Taiwan]]<ref name=":132222"/><ref name=":43" /><ref name=":03">{{Cite journal|last=Chemenda|first=A. I.|last2=Yang|first2=R. K.|last3=Hsieh|first3=C. -H.|last4=Groholsky|first4=A. L.|date=1997-06-15|title=Evolutionary model for the Taiwan collision based on physical modelling|url=http://www.sciencedirect.com/science/article/pii/S0040195197000255|journal=Tectonophysics|series=An Introduction to Active Collision in Taiwan|volume=274|issue=1|pages=253–274|doi=10.1016/S0040-1951(97)00025-5|bibcode=1997Tectp.274..253C}}</ref>

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This model is developed based on the geological evolution of Alpine and Apennine subduction.<ref name=":103">{{Cite journal|last=Vignaroli|first=Gianluca|last2=Faccenna|first2=Claudio|last3=Jolivet|first3=Laurent|last4=Piromallo|first4=Claudia|last5=Rossetti|first5=Federico|date=2008-04-01|title=Subduction polarity reversal at the junction between the Western Alps and the Northern Apennines, Italy|url=http://www.sciencedirect.com/science/article/pii/S004019510700457X|journal=Tectonophysics|volume=450|issue=1–4|pages=34–50|doi=10.1016/j.tecto.2007.12.012|bibcode=2008Tectp.450...34V}}</ref>

Similarly, two oceanic plates move towards each other. The subduction process ceases with the involvement of buoyant continental block. A new slab is formed at the overriding plate owing to the regional compression and the difference in density between the continental block and oceanic plate.<ref name=":103" /> An [[orogenic wedge]] is built.<ref name=":103" /> However, there is an obvious space problem about how to accommodate two slabs. The solution is the new developing slab moves not only vertically, but also laterally leading to a deep strike-slip movement.<ref name=":103" /> The development of co-existence of two opposite slabs is described as a double sided subduction<ref>{{Cite journal|last=Tao|first=Winston C.|last2=O'connell|first2=Richard J.|date=1992-06-10|title=Ablative subduction: A two-sided alternative to the conventional subduction model|url=http://onlinelibrary.wiley.com/doi/10.1029/91JB02422/abstract|journal=Journal of Geophysical Research: Solid Earth|language=en|volume=97|issue=B6|pages=8877–8904|doi=10.1029/91JB02422|issn=2156-2202|bibcode=1992JGR....97.8877T}}</ref> or doubly convergent wedge.<ref name=":103" /> Eventually, the development of new slab grows and slides onto the old slab. The old slab breaks off and the orogenic wedge collapses. The new slab stops the lateral motion and subducts beneath.<ref name=":103" /> The direction of subduction system changes.<ref name=":103" />[[File:Doubly_Convergence.gif|thumb|457x457px|Evolution of doubly convergence model: Brown colour represents the Continental plate; White colour represents the oceanic plate; C1. The plate with both continental and oceanic plate subducts beneath; 2. The continental block engage in the subduction with building orogenic wedge; 3. The new slab develops and two slabs exhibit a deep strike-slip movement (Double circle means pointing out of the screen; Cross inside the circle means pointing into the screen; 4. New slab moves further downward; 5. The old slab breaks off; 6. The new slab subducts beneath.|center]]

=== Lithosphere break-up ===

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The initial setting of the simulated [[Subduction|subduction zone]] model is confined by two pistons. The piston connected to the overriding plate is locked, while the piston linking to subducting plate is subjected to a constant rate of compression.<ref name=":113" /> More importantly, there is a relatively thin [[Volcanic arc|magmatic arc]] and pre-existing fault dipping towards the subducting plate at the overriding plate.<ref name=":113" /> The detachment of the pre-existing fault occurs when buoyant [[continental margin]] is in contact with the overriding plate.<ref name=":113" /> It is because the buoyant margin resists [[subduction]] and significantly increases the [[Friction|frictional force]] in the contact region.<ref name=":113" /> The subduction then stops. Subsequently, the new subducting slab develops at an overriding plate with the continuous compression.<ref name=":113" /> The new developing slab eventually penetrates and breaks the old slab.<ref name=":113" /> A new subduction zone is formed with an opposite polarity to the previous one.<ref name=":113" />

In reality, the magmatic arc is a relatively weak zone at the overriding plate because it has a thin lithosphere and is further weakened by high heat flow<ref>{{Cite journal|last=Currie|first=Claire A.|last2=Hyndman|first2=Roy D.|date=2006-08-01|title=The thermal structure of subduction zone back arcs|url=http://onlinelibrary.wiley.com/doi/10.1029/2005JB004024/abstract|journal=Journal of Geophysical Research: Solid Earth|language=en|volume=111|issue=B8|pages=B08404|doi=10.1029/2005JB004024|issn=2156-2202|bibcode=2006JGRB..111.8404C}}</ref><ref>{{Cite journal|last=Currie|first=C. A|last2=Wang|first2=K|last3=Hyndman|first3=Roy D|last4=He|first4=Jiangheng|date=2004-06-30|title=The thermal effects of steady-state slab-driven mantle flow above a subducting plate: the Cascadia subduction zone and backarc|url=http://www.sciencedirect.com/science/article/pii/S0012821X04002687|journal=Earth and Planetary Science Letters|volume=223|issue=1–2|pages=35–48|doi=10.1016/j.epsl.2004.04.020|bibcode=2004E&PSL.223...35C}}</ref> and hot fluid.<ref>{{Cite journal|last=Arcay|first=D.|last2=Doin|first2=M.-P.|last3=Tric|first3=E.|last4=Bousquet|first4=R.|last5=de Capitani|first5=C.|date=2006-02-01|title=Overriding plate thinning in subduction zones: Localized convection induced by slab dehydration|url=http://onlinelibrary.wiley.com/doi/10.1029/2005GC001061/abstract|journal=Geochemistry, Geophysics, Geosystems|language=en|volume=7|issue=2|pages=Q02007|doi=10.1029/2005GC001061|issn=1525-2027|bibcode=2006GGG.....7.2007A}}</ref><ref>{{Cite journal|last=Honda|first=Satoru|last2=Yoshida|first2=Takeyoshi|date=2005-01-01|title=Application of the model of small-scale convection under the island arc to the NE Honshu subduction zone|url=http://onlinelibrary.wiley.com/doi/10.1029/2004GC000785/abstract|journal=Geochemistry, Geophysics, Geosystems|language=en|volume=6|issue=1|pages=Q01002|doi=10.1029/2004GC000785|issn=1525-2027|bibcode=2005GGG.....6.1002H}}</ref> Pre-existing faults in this simulation are also common in the magmatic arc.<ref>{{Cite journal|last=Toth|first=John|last2=Gurnis|first2=Michael|date=1998-08-10|title=Dynamics of subduction initiation at preexisting fault zones|url=http://onlinelibrary.wiley.com/doi/10.1029/98JB01076/abstract|journal=Journal of Geophysical Research: Solid Earth|language=en|volume=103|issue=B8|pages=18053–18067|doi=10.1029/98JB01076|issn=2156-2202|bibcode=1998JGR...10318053T}}</ref> This experiment is a successful analogy to subduction polarity reversal happening at Kamchatka in early Eocene<ref name=":54" /><ref>{{Cite journal|last=Konstantinovskaia|first=Elena A|date=2000-10-15|title=Geodynamics of an Early Eocene arc–continent collision reconstructed from the Kamchatka Orogenic Belt, NE Russia|url=http://www.sciencedirect.com/science/article/pii/S0040195100001323|journal=Tectonophysics|volume=325|issue=1–2|pages=87–105|doi=10.1016/S0040-1951(00)00132-3|bibcode=2000Tectp.325...87K}}</ref> and the active example at Taiwan region<ref name=":113" /><ref name=":03" /> as well as at Timor.<ref>{{cite journal|last1=Silver|first1=Eli A.|last2=Reed|first2=Donald|last3=McCaffrey|first3=Robert|last4=Joyodiwiryo|first4=Yoko|title=Back arc thrusting in the Eastern Sunda Arc, Indonesia: A consequence of arc-continent collision|journal=Journal of Geophysical Research: Solid Earth|date=1983-09-10|volume=88|issue=B9|pages=7429–7448|doi=10.1029/JB088iB09p07429|bibcode=1983JGR....88.7429S}}</ref><ref>{{Cite journal|last=Snyder|first=D. B.|last2=Prasetyo|first2=H.|last3=Blundell|first3=D. J.|last4=Pigram|first4=C. J.|last5=Barber|first5=A. J.|last6=Richardson|first6=A.|last7=Tjokosaproetro|first7=S.|date=1996-02-01|title=A dual doubly vergent orogen in the Banda Arc continent-arc collision zone as observed on deep seismic reflection profiles|url=http://onlinelibrary.wiley.com/doi/10.1029/95TC02352/abstract|journal=Tectonics|language=en|volume=15|issue=1|pages=34–53|doi=10.1029/95TC02352|issn=1944-9194|bibcode=1996Tecto..15...34S}}</ref>

[[File:Lithospheric_break-up_model_setup.svg|thumb|444x444px|A. Chemenda's Experiment setup of lithosphere break-up model: White colour indicates the oceanic plate ( Higher density) ; Brown colour indicates the continental plate ( Lower density) ;Green colour shows the pre-existing fault ; The plates represented by hydrocarbons floats at the asthenosphere represented by water.|center]][[File:Lithoshperic_break-up.gif|thumb|444x444px|The evolution diagram showing how the subduction reversal initiated by a pre-existing fault at the overriding plate. 1: Compression pushing ; 2: New slab develops with the failure of the fault ; 3: New slab penetrates ; 4: New slab breaks the old slab|center]]