Geodynamics of the Alpine Mediterranean chains Overview of their structure & history Mark. R. Handy Outline • Alps • Carpathians & Pannonian Basin • Dinarides • Northern Apennines • Summary of tectonic history Accreted Adriatic & European units Handy et al., simplified from Schmid et al. 2004, 2008 Carpathians European Alps Plate Adriatic Plate European Plate Dinarides Apennines ? Alps Handy et al., simplified from Schmid et al. 2004, 2008 European Carpathians Plate Alps Adriatic Plate European Plate Dinarides Apennines ? Plate tectonic map of theJurassic-Cretaceous Alps 8 û 10 û 12 û boundarY PALEOGEOGRAPHIC (Neotethys suture) UNITS IN THE ALPS Paleogene -Europe Rhenodanubian flysch modified after Froitzheim et al. ( 1996 ) ) Adria Walsertal zone boundarYNFP-20 EAST suture Z Ÿ rich Glockner nappe window Lower plate (Europe)plate Northern Calcareous Alps Tauern W Š gital flysch Venediger nappe 47 û Schlieren flysch Falknis Sulzfluh Bern dow Matrei zone NPB NPB (Alpine Tethys win Helvetic Nappes Austroalpine Alps Gurnigel flysch Tasna Schams Arosa zone Engadine Ela NFP-20 WEST Aar Gotthard Ortler Adula Platta Suretta Tambo A v Bernina Upper plate (Adria) epontine Geneva Be. Margna Sella Malenco Adamello Breccia Insubric line 46 û nappe ECORS-CROP Southern Alps Antrona Generoso M. Rosa Giudicarie line M. Nudo Dent Blanche - Sesia Insubric line Roignais Versoyen Europe Grand European- margin Paradiso Milano Canavese AdriaValais basin Grenoble Lanzo Oceanic units: boundarYBrian onnais terrane 45 û Torino Present Piemont-Liguria basin Dora Maira plate Relics of Alpine Tethys Margna-Sesia fragment N Apulian margin Froitzheim et al. 1996 100 km Meliata-Hallstatt basin The Alps – the traditional geological-geographical subdivision Eastern Alps Engadin Window Jura Rechnitz Window Central Alps Préalpes Klippe Tauern Window Dente Blanche Klippe Southern Alps Western Alps Handy et al. 2010 Zermatt area - the Matterhorn-Dent Blanche Klippe S N Dent Blanche klippe Bernhard N Marthaler 2005 Mischabel Zermatt-Saas Zone Combin Zone backfold Two orogens – two baric events Handy & Oberhänsli 2004 Late Cretaceous (110-90 Ma) “Eo-Alpine” subduction Paleogene (65-20 Ma) subduction TRANSALP NFP -E NFP-W The Alps – AS transects ECORS-CROP Handy et al. 2010 “Backfolds” & Periadriatic Fault Crustal structure • very non-cylindrical structure 1 • lower crustal wedges • two orogens • massive accretion of lower plate 2 European lower crust 3 4 Eo-Alpine orogen 3 2 1 4 Schmid et al. 2004 Subduction Adriatic lower crust polarity reversal Plates Europe Periadriatic Fault System & first-order crust-mantle structures Adria • The PFS is NOT the Alpine Metamorphism suture • The PFS is different in the E than in the W! Thermal domes upper mantle of Adria at crustal levels! Deep structure PFS Europe Ivrea Body Solarino & Kissling 1997 anomaly Adria Schmid et al. 1989 The Periadriatic Fault System - its components IN SEMP MM NT KB Pustertal Gailtal Lavantal Giudicarie Balaton PF Tonale Insubric Canavese Cremosina modified from Schmid et al. 1989 Periadriatic Fault System & related magmatites 23-10 Ma 34-25 Ma 150 km Adriatic indenter Handy et al. 2010 Post-20 Ma lateral extrusion in the E. Alps Neogene deformation Handy et al. 2015 77 km Denudation since 30 Ma: 166 km extension • 1/3 due to extensional unroofing 77 km extension • 2/3 due to post- nappe folding & 70-80 km indentation erosion Adriatic indenter Favaro et al. 2017 indenter Brenner NorMal Adriatic Fault Ratschbacher et al. 1991 Fügenschuh et al. 1997 Analogue models of lateral extrusion Ratschbacher et al. 1991 Free side = Carpathian rollback Europe Pannonian subduction orogen basin Rosenberg et al. 2007 Adria Ratschbacher et al. 1991a Indentation produces coeval folds, conjugate strike-slip faulting and block rotation 15 Periadriatic Fault System & related magmatites Veneto intrusives Bergell granitoids Handy et al. 2010 Lithospheric mantle source of Periadriatic granitoids “Slab breakoff led to heating of Von Blankenburg & Davies 1995 the overriding lithospheric mantle “Trace element and isotopic composition by upwelling asthenosphere, suggest that they have been formed by low- melting of its enriched layers, degree melting of the mechanically stable and thus to bimodal magmatism.” lithospheric mantle. There is no evidence for melting of asthenospheric mantle.” Von Blankenburg & Davies 1995 von Blanckenburg & Davies 1995 Peripheral basins of the Alpine chains Adapted from Allen et al. 1986 Northern Alpine (Molasse) & Southern Alpine (Po) Basins Structure of the „Molasse“ Basin E • Basin is deeper and more deeply eroded in the W than in the E • Shortening stops at 17 Ma in E W Kuhlemann & Kempf 2002 W E Oligo-Miocene coarse clastics (USM) in W are reduced in E At c. 20-18 Ma, the E. Molasse basin became overfilled and orogen-parallel flow of rivers in the basin changed from W-to-E to E-to-W overlapping Adriatic. Europe Moho “hole” & European Mohos (Ivrea anomaly) depressed Moho above hanging Adria Adriatic slab Liguria Moho depth map of Alps & Apennines Spada et al. 2013, Fig. 11 Subduction polarity beneath the Alps slab gap ? A B European slab only 6 stations PYROPE in the E Alps CIFALPS Adriatic slab? Lippitsch et al. 2003 A B A B Zhao et al. 2016 / E Alpine NW S NE SW E European slab Adriatic slab ? +Vp anomalies down to 200 km +V anomalies down to 450 km! => Slabs above OliGo-Miocene breakoff p => Slabs never broke off ? Alps surface & subsurface viewed from NE Handy, Hetenyi, Kissling, Fügenschuh Ivrea Zone northern Ligurian Nice Tethyan ophiolites Apennines Sea northern Turin Dinarides Po Basin Jura Mtns Adriatic Sea Venice Periadriatic F. Basel Istria Southern Alps Rhine Graben Periadriatic Fault Molasse Basin Central Giudicarie Fault Eastern Alps Alps slab slab gap ? Slab ? Mantle Transition Zone entrained Cretaceous-Eocene European slab Alps surface & subsurface features viewed from SE Simplon Fault Jura Mtns Rhine Graben Molasse Basin Tethyan ophiolites Basel Brenner Fault Munich Tauern Window SEMP Fault Nice Vienna crustal wedge Pannonian Basin ? slab tear Western - Central ? Cretaceous-Eocene Mantle Transition Zone Alpine suture Alps slab Eastern Alps Slab Mio-Pliocene Eastern Alps subduction interface entrained Cretaceous-Eocene European slab Transects of Alps viewed from the SE Active seismic transects of the 1980s & 1990s Passive seismic swaths (AlpArray, CIFALPS-1) Passive swaths transects (AlpArray, 4D-MB) Basel NFP20E ECORS-CROP NFP20W TRANSALP Munich CIFALPS EASI -1 Swath D Nice Vienna AlpArray D Mantle Transition Zone Slab structure: Lippitsch et al. 2003 MTZ structure: Lombardi et al. 2009 Moho: Spada et al. 2013 Geology: Bigi et al. 1989, Schmid et al. 2004 The Alpine (European) slab in tomography TomographiC section GeologiC sections b b Courtesy of Wim Spakman E. Alps Calabria 1200km b Handy et al. 2010 Spakman & Wortel 2004Tomography W. Spakman Development of the Alpine Slab Tomography & Geology on the same scale 118 Ma b 20 Ma 1200 km obtained from minimum shortening 20 Ma in the C. Alps Handy et al. 2010 Tomography W. Spakman Carpathian-Pannonian System Handy et al., simplified from Schmid et al. 2004, 2008 Carpathians European Plate Alps Pannonian Basin Adriatic Plate European Plate Dinarides Apennines ? Carpathian-Pannonian System Handy et al., simplified from Schmid et al. 2004, 2008 European Plate accreted Adria accreted Europe Adriatic Plate European Plate ? 3D diagram of Carpathian-Pannonian system Tisza ALCAPA (mixed European (Adriatic) and Adiatic) Dacia (European) Mid-Hungarian Fault Zone Dinarides, Moho S. Alps (Adriatic) no slab Ustaszewski et al. 2008 Neogene Basins Transylvanian Basin Pannonian Basin Schmid et al. 2008 Neogene extensional structures of the Pannonian Basin C A’ C’ Transylvanian Basin A Horvath et al 2006 Tari et al 2006 C C’ A A’ Rollback Subduction W E Pannonian Basin Carpathians trench retreat Royden, Horvath, and Burchfiel, 1982, GSA Bull, 23, 717-725 Miocene-recent magmatism as a tracer of rollback subduction Ages (Ma) of calc-alkaline 21-8 magmatism 15-9 12-8 10-0.03 Moesia Seghedi & Downes 2011 Surface uplift & Pannonian tectonics Strath terraces at Visegrad Uplift, river incision and erosion shown by ancient Danube strath terraces at Visegrád, upstream of Budapest. Exposure age of terraces: 0 to 250ky Incision rate: ~1.5 mm/y From S.Cloetingh Clockwise migration of foredeep deposition around the Carpathian arc 22-27 Ma 16.5-17.5 Ma 13.5-15.5 Ma Vertical bars = 11.5 - 8 Ma foredeep sediment residence times Internal to external and lateral shifts in foredeep depocentre accellerated in latest Early- Mid Miocene time (from 7 to 45 cm/y at 15.5 Ma) Meulenkamp et al. 1996 3.7 – 1.8 Ma Foredeep migration related to rollback subduction & Pannonian extension 16.5 Ma 17.5 Ma • Drastic increase at 16.5 Ma 15.5 Ma • Clockwise foredeep 19 Ma migration probably traces direction of Miocene slab tearing 11.5 Ma Meulenkamp et al. 1996 Meulenkamp et al. 1996 Block rotations during rollback subduction 22 Ma 20 Ma Paleomagnetics 17 Ma 13 Ma 11 Ma Today Csontos & Vörös 2004 ALCAPA Alpine Tethys Embayment TISZA Balla 1987 Detached slabs & the slab „graveyard“ No slab Wortel & Spakman 2000 E Alps slab Vrancea slab 200 km 200 km 600 km 600 km detached slab of Alpine Tethys Vrancea slab – hangs in the “wrong” place, just below the orogenic front Miocene thrust front unconformably overlain by Pliocene sediments Focsan depression Matenco et al. 2007 Tomography of W. Spakman Dinarides Handy et al., simplified from Schmid et al. 2004, 2008 European Carpathians Plate Alps Adriatic Plate European Plate Dinarides Apennines ? Sutures of two oceans - Alpine Tethys & Neotethys after Bernoulli 2001 PelaGonian & Sub HiGh Karst Zone Dalmatian Zone -Pel. Zone Ionian basin Alpine Tethys suture Apulian platform Valais Ionian Sea Neotethys suture Sava, Izmir-Ankara Zones Schmid et al 2011, in prep Cross section of the Dinarides LOWER PLATE = ADRIA Paleogene UPPER PLATE = EUROPE Paleogene nappe stack topped by Suture Late Cretaceous nappe stack obducted W. Vardar ophiolite nappe topped by obducted E.