Arc-Continent Collision PDF
Preview Arc-Continent Collision
Frontiers in Earth Sciences SeriesEditors:J.P.Brun,O.Oncken,H.Weissert,W.-C.Dullo . Dennis Brown (cid:129) Paul D. Ryan Editors Arc-Continent Collision Editors Dr.DennisBrown Dr.PaulD.Ryan InstitutodeCienciasdelaTierra NationalUniversityofIreland,Galway “JaumeAlmera”,CSIC Dept.Earth&OceanSciences(EOS) C/LluisSoleiSabariss/n UniversityRoad 08028Barcelona Galway Spain Ireland [email protected] [email protected] Thispublicationwasgrant-aidedbytheNationalUniversityofIreland,Galway ISBN978-3-540-88557-3 e-ISBN978-3-540-88558-0 DOI10.1007/978-3-540-88558-0 SpringerHeidelbergDordrechtLondonNewYork LibraryofCongressControlNumber:2011931205 # Springer-VerlagBerlinHeidelberg2011 Thisworkissubjecttocopyright.Allrightsarereserved,whetherthewholeorpartofthematerialis concerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting, reproductiononmicrofilmorinanyotherway,andstorageindatabanks.Duplicationofthispublicationor partsthereofispermittedonlyundertheprovisionsoftheGermanCopyrightLawofSeptember9,1965,in itscurrentversion,andpermissionforusemustalwaysbeobtainedfromSpringer.Violationsareliableto prosecutionundertheGermanCopyrightLaw. Theuseofgeneraldescriptivenames,registerednames,trademarks,etc.inthispublicationdoesnotimply, evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevantprotectivelawsand regulationsandthereforefreeforgeneraluse. Coverdesign:deblik,Berlin Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Preface One of the key areas of research in the Earth Sciences are processes that occur along the boundaries of the tectonic plates that make up Earth’s lithosphere. Of particular importance are the processes of tectonic accretion and erosion along convergentplateboundaries.Oneoftheprincipalmechanismsofaccretionoccurs whenintra-oceanicvolcanicarcscollidewiththemarginofacontinentinwhatis calledarc–continentcollision.Arc–continentcollisionhasbeenoneoftheimpor- tant tectonic processes in the formation of mountain belts throughout geological timeandcontinuestodayalongtectonicallyactiveplateboundariessuchasthosein the SW Pacific or the Caribbean. Well-constrained fossil arc–continent collision orogens supply thethird and fourthdimension(depth andtime)thataregenerally missing from currently active examples where tectonic processes such as sub- duction, uplift and erosion, and the formation of topography can be observed. Arc–continent collision is also thought to have been one of the most important processesinvolvedinthegrowthofthecontinentalcrustovergeologicaltime,and mayalsoplayanimportantroleinitsrecyclingbackintothemantleviasubduction. The integration of research between active and fossil arc–continent orogens pro- videkeydatafortheunderstandingofhowplatetectonicsworkstoday,andhowit might have worked in the past. Understanding the geological processes that take placeduringarc–continentcollisionisthereforeofimportanceforourunderstand- ing of how collisional orogens evolve and how the continental crust grows or is destroyed.Furthermore,zonesofarc–continentcollisionareproducersofmuchof theworldsprimaryeconomicwealthintheformofminerals,sounderstandingthe processesthattakeplaceduringthesetectoniceventsisofimportanceinmodeling howthismineralwealthisformedandpreserved. Arc–continent collision orogeny is generally short-lived, lasting from c. 5 to 20 My, although much longer-lived regional events do occur. The duration of an arc–continent collision orogeny depends on a number of factors, among which the obliquityofthe collision,thesubductionvelocity, andthestructuralarchitectureof thearcandthecontinentalmargininvolvedareofprimaryimportance.Inthisbook wedefinetheonsetofarc–continentcollisionasthearrivaloftheleadingedgeofthe continental margin (continental crust to oceanic crust transition) at the subduction zone, something that is often difficult to identify in the geology of an orogen. Thinned, extended continental margins often reach 150–400 km in width and are highly structured. There is now widespread evidence that this thinned crust can be deeply subducted (>200 km) before being returned to the surface as high- and ultrahigh-pressure rocks. Dating these high-pressure rocks can provide important constraintsonthetimingofarrivalofthecontinentalmarginatthesubductionzone. v vi Preface Afurtherconstraintcanbesuppliedbythearcvolcanics,whosegeochemistrymay record the entrance of continentally derived sediments, or the thinned continental crust itself, into the subduction zone. In currently active systems, imaging the subducted continental lithosphere with techniques such as seismic tomography can also providekey data for determining the timingof on-setof collision and the rates at which the continental crust is being subducted. With the arrival of thicker continentalcrust(c.20–30kmthick)atthesubductionzonethedevelopingorogen is generally uplifted to above sea level where it begins to erode and provide sediment to a foreland basin and across the arc–continent suture zone and the forearc. As convergence continues, the active volcanic front generally shuts down shortlyaftertheentryofthecontinentalcrustintothesubductionzone,andvolcanic activity can move away from the subduction zone to continue outboard of it for sometimebeforestoppingcompletely.Duringthefinalstageofcollision,achange inthelocationofthesubductionzonecantakeplace,furthermarkingtheendofthe arc–continentcollision.Thefinalresultofthearc–continentcollisionisasignificant change in the structural architecture, composition, and rheology of the continental margin. Theaimofthisbookistobringtogetheraseriesofpapersthatarededicatedtothe investigationofthetectonicprocessesthattakeplaceduringarc–continentcollision. A further aim is to investigate how tectonic processes influence the large-scale geological characteristics of these accretionary orogens and their mineral wealth. Finally, specific examples of arc–continent collisions are investigated. These range in age from the Neoproterozoic to those that are currently active, covering a large portion ofgeological time.To advance these aims, aseries ofpointsare developed whichweattempttoaddresswherepossibleineachpaper.Thesepointsare: (cid:129) Thelarge-scalecrustandmantlestructure. (cid:129) Thenatureandroleofthelithosphereandasthenosphericmantleinthedynamics andchemistryofthesubductionandcollisionprocesses. (cid:129) Processesthattakeplacedeepwithinthesubductionchannelinpureintraoceanic subductionandduringthesubductionofthecontinentalcrust. (cid:129) The geochemical and petrological evolution of the arc both before and during collision. (cid:129) Thenatureofthecontinentalmarginanditsresponsetothecollision. (cid:129) Theformationoftopographyandtheerosionofthedevelopingmountainbeltto formaforelandandasutureforearcbasin. (cid:129) Fore-arcsubductionoraccretion. (cid:129) Theemplacementofophiolitesandultramaficmassifs. (cid:129) Metamorphismwithinthedevelopingorogen. (cid:129) Thepossibilityofchangesinthelocationofthepost-collisionsubductionzone. (cid:129) Placeconstraintsonthedurationofarc–continentcollisionorogeny. (cid:129) Recycling,orgrowthanddestructionofthecontinentalcrust. The book is organised in four sections. In the first section, numerical modeling and natural examples are used to look at the three main players involved in arc– continent collision; the continental margin, the volcanic arc, and the subduction zone. In the second section, natural examples of arc–continent collisions are described.Inthethirdsection,modelingofvariousaspectsofarc–continentcollision are presented. In the fourthsection, we bring together the materialpresented in the previoussectionsaddressingtheseriesofpointsoutlinedaboveand,wherepossible, attempttoprovideanswerstothem. Preface vii Finally,thispublicationwasgrant-aidedbythePublicationsFundoftheNational UniversityofIreland,Galway.Also,wewouldliketoextendourthankstothosewho kindlyprovidedreviewsofthepapers.ThisisanIGCP524publication. Barcelona,Spain DennisBrown Galway,Ireland PaulD.Ryan . Contents PartI TheMainPlayers 1 RiftedMargins:BuildingBlocksofLaterCollision ..................... 3 T.RestonandG.Manatschal 2 Intra-oceanicSubductionZones ......................................... 23 T.V.Gerya 3 TheSubductabilityofContinentalLithosphere: TheBeforeandAfterStory .............................................. 53 J.C.AfonsoandS.Zlotnik 4 TheSeismicStructureofIslandArcCrust ............................. 87 A.J.Calvert 5 VerticalStratificationofComposition,Density,andInferred MagmaticProcessesinExposedArcCrustalSections ................ 121 S.M.DeBariandA.R.Greene 6 TheGenerationandPreservationofMineralDeposits inArc–ContinentCollisionEnvironments ............................. 145 R.J.HerringtonandD.Brown PartII SpecificExamplesofArc-ContinentCollision 7 TheNatureoftheBandaArc–ContinentCollision intheTimorRegion ..................................................... 163 R.Harris 8 TheArc–ContinentCollisioninTaiwan ............................... 213 T.Byrne,Y.-C.Chan,R.-J.Rau,C.-Y.Lu, Y.-H.Lee,andY.-J.Wang 9 EarlyEoceneArc–ContinentCollisioninKamchatka,Russia: StructuralEvolutionandGeodynamicModel ......................... 247 E.Konstantinovskaya 10 TheAsia–Kohistan–IndiaCollision:ReviewandDiscussion ......... 279 J.-P.Burg 11 ProcessesofArc–ContinentCollisionintheUralides ................. 311 D.Brown,R.J.Herrington,andJ.Alvarez-Marron ix
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