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Sicily - 1990 Top Driven Asymmetric Mantle Convection Don Anderson Carlo Doglioni.

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Presentation on theme: "Sicily - 1990 Top Driven Asymmetric Mantle Convection Don Anderson Carlo Doglioni."— Presentation transcript:

1 Sicily Top Driven Asymmetric Mantle Convection Don Anderson Carlo Doglioni

2 Modified after Thybo, 2006 LowVelocity Zone Riguzzi et al Tectonophysics decoupling Vs, km/s

3 Modified after Thybo, 2006 LowVelocity Zone Riguzzi et al Tectonophysics

4 K Canonical 1600 K adiabat SUBADIABATIC REGION Modified after Xu et al. 2011, GJI Depth km Vs Dry lherzolite solidus 50 ppm H 2 O Tp 4 km/s Vs wavespeed Geotherm from seismic gradients Thermal bump region (OIB source) SUPERDIABATIC REGION T LVZ CONDUCTIVE LITHOSPHERE insulation Lehmann discontinuity 200 pargasite breakdown

5 Cuffaro & Doglioni, 2007 GSA Sp. Publ. Tectonic Equator WESTWARD DRIFT OF THE LITHOSPHERE AND TECTONIC EQUATOR Shallow hotspot reference frame

6 Cuffaro & Doglioni, 2007 GSA Sp. Publ. Westward drift of plates constrained by viscosity variations in the LVZ LVZ

7 Modified after Yuan & Beghei, 2013 EPSL In Doglioni & Anderson 2015, GSA-AGU Volume The tectonic equator fits the SKS of the LVZ

8 Mid Atlantic Ridge Asymmetric rifts Doglioni et al. 2014, Geoscience Frontiers

9 Panza et al Geology Asymmetric S-wave signature of ridges (faster western side)

10 Chalot-Prat & Doglioni in prep. Westerly migrating ridge  LVZ & LID lateral heterogeneity & asymmetry

11 KURILI N-CORDILLERA Harabaglia & Doglioni, 1998, GRL Asymmetric signature of topography and gravity

12 Riguzzi et al. 2010, Tectonophysics Asymmetric dip of slabs moving along the tectonic equator

13 slab dip vs. lithosphere age same dip for variable ages = no correlation Cruciani et al., 2005, EPSL No negative buoyance as cause of

14 Doglioni et al ESR

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17 CONVERGENCE HINGE WRT UPPER PLATE SUBDUCTION RATE VOLUME RATE lengthmm/yr km3/yr N-AmericaBarbados ,5 S-AmericaSandwich S-America- AntarcticaAleutians ,9 Macquarie- NewZealandCarpathians ,3 Papua- NewGuineaN-Japan ,5 Indonesia Nankai- Ryukyu-Phil ,3 Himalaya Izu Bonin- Marianas ,6 Zagros NNewZealand- Tonga-Kerma ,2 Dinarides Bismarck- Solomon ,7 HellenidesBanda ,5 CyprusApennines Taiwan- BorneoTotal length Alps New Hebrides Caucasus Total length CONVERGENCE HINGE WRT UPPER PLATE SUBDUCTION RATE VOLUME RATE lengthmm/yr km3/yr N-America ,9Barbados S-America ,7Sandwich S-America- Antarctica ,9Aleutians Macquarie- NewZealand ,5Carpathians Papua- NewGuinea ,5N-Japan Indonesia ,8 Nankai- Ryukyu-Phil. Himalaya ,8 Izu Bonin- Marianas Zagros ,5 NNewZealand- Tonga-Kerma Dinarides ,1 Bismarck- Solomon Hellenides Banda Cyprus ,4Apennines Taiwan- Borneo ,1Total length Alps8501-0,50.50,04 New Hebrides ,2 Caucasus ,5 Total length E-NEW-SW Slab recycling volumes ≈ 306 km 3 /yr Doglioni & Anderson, 2015, GSA-AGU Volume 3 times larger volumes of lithosphere are westerly subducted

18 Doglioni et al ESR

19 Ritsema, 2003 Faster velocity at 600 km of the western Pacific: cooler and deeper western slabs

20 B NE A 0 km NW 2 vergences 1 vergence 0 km Dal Piaz, 1997 Scrocca et al., 2005, Tectonics 1300°C basement Asymmetric subductions & related orogens

21 S=H-L convergencesubduction heat flow VS=VH-VL Asymmetric subductions and related orogens Doglioni et al ESR

22 Doglioni & Anderson, 2015 GSA-AGU Volume

23 “Westward” drift of the lithosphere Doglioni & Anderson, 2015 GSA-AGU Volume POLARIZED CONVECTION

24 Doglioni & Anderson, 2015 GSA-AGU Volume “Westerly” sheared lithosphere: Slab pull or horizontal tidal torque? confined descentdiffused compensating passive ascent ridge

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26 It is the asymmetry that generates the phenomenon PIERRE CURIE Thanks to: Eugenio Carminati, Mattia Crespi, Françoise Chalot-Prat, Marco Cuffaro, Fabrizio Innocenti, Anatoli Levchin, Giuliano Panza & Federica Riguzzi


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