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  • The PICASSO project: MT Investigation in Southern Spain and Morocco - Results of Phase I and outlook on Phase IIDI41A-1792

    The PICASSO project: MT Investigation in Southern Spain and Morocco - Results of Phase I and outlook on Phase II

    Duygu Kiyan1 , Jan-Philipp Schmoldt1,2, Alan G. Jones1 , Colin Hogg1, Oriol Rosell3 Duygu Kiyan1 , Jan-Philipp Schmoldt1,2, Alan G. Jones1 , Colin Hogg1, Oriol Rosell3

    1Dublin Institute for Advanced Studies, School of Cosmic Physics, 5 Merrion Square, Dublin 2, Ireland 2National University of Ireland, Galway, Department of Earth and Ocean Science, University Road, Galway, Ireland 3Universitat de Barcelona, Departament de Geodinàmica i Geofísica, Martí i Franques s/n, 08028 Barcelona, Spain

    Contact: [email protected]

    Motivation Phase I Phase IITectonic map Overview of field area

    • Study Internal structures of the arc- shaped

    Betic-Rif mountain systemBetic-Rif mountain system

    • Derive mechanisms of the tectonic processes

    given by the compressional

    European and African plates and the Alboran

    microplate beneath the

    Mediterranean Sea.Mediterranean Sea.

    • Define the geometry of electrical lithosphere-

    asthenosphere boundary

    Platt, 2007

    asthenosphere boundary

    • Investigate reason for topographic elevation of

    central Spain

    Missing mantle root beneath

    Atlas mountain rangecentral Spain

    • Enhance knowledge about the process of

    recycling the lithosphere back into the mantle Phase IIrecycling the lithosphere back into the mantle• Test hypotheses for lack of mantle root beneath

    the Atlas mountains range

    Phase II

    • Focus on the formation of

    Atlas Mountain rangethe Atlas mountains range

    • Meet challenges in dealing with 3D subsurface

    structures

    Atlas Mountain range

    • Studying the crustal and

    upper mantle structuresTeixel et al, 2007Inversion parameters2D Inversion Result

    structures upper mantle structuresTeixel et al, 2007

    Conclusions

    •Period range: 10-3 – 105

    • Interp. data: 5 freq. / decade

    and smooth curves

    • Fixing damping factor = 10,000

    • Start model: Stratified

    ― Crust (30-40 km depth): 100 Ωm― Lithosphere (extends to 30-150 km depth): 1000 Ωm― Asthenosphere (bottom halfspace): 25 Ωm

    External InternalTajo Basin

    Betics

    NS

    Phase IFocus on the structures of the

    Fieldwork

    ConclusionsNote: Model is better constrained in the north than

    • Fixing damping factor = 10,000

    • Error floor (%): ϕTM=ϕTE=5

    ρTM=10, ρTE=20 • τ = 3, α = 1, β = 2• RMS = 2.736

    ― Asthenosphere (bottom halfspace): 25 Ωm― Ocean (Med. Sea): 0.33 Ωm• Initially sharp boundary inversion with fixed ocean,

    crust-mantle boundary and LAB

    • Subsequent smooth inversion with fixed ocean and

    lithosphere

    c ccd c

    NS

    • Focus on the structures of the

    Betic Mountain range and the

    central Spain

    Fieldwork

    Collaboration of DIAS with

    Universities of Barcelona and

    Note: Model is better constrained in the north than

    in the Betics region

    a) Highly conductive Mediterranean Sea impedes

    lithosphere

    • Smooth inversion with only ocean fixed

    c

    cd c

    eb

    RESULT

    central Spain

    • Difficult signal-to-noise ratio due

    to low solar activity and populated

    Universities of Barcelona and

    Bari

    • Duration Sep.-Dec. 2009

    Tectonic map of southern Spainthe investigation of structures beneath

    b) Conductive upper crust extends down to ~20 Km

    c) Various small scale features observed in upperf g

    S N

    RESULTto low solar activity and populatedfieldwork area

    • Duration Sep.-Dec. 2009

    (ongoing)

    • 2 Profiles (~200 km, ~400 km)

    c) Various small scale features observed in upper

    and lower crust

    d) Upward continuation of resistive structure

    Alboran Domain Crust

    Iberian Crust

    f g

    Geology

    • 2 Profiles (~200 km, ~400 km)

    • 42 Phoenix broadband MT

    stationsLithosphere

    d) Upward continuation of resistive structure

    coincides with Betics Front

    e) An upper mantle conductive feature is apparent LithosphereLithosphereGeology

    • Profile crossing the Tajo basin and

    the Betic Chain, the latter formed

    stations

    • 23 LVIV long-period MT stationLithosphere

    TRANSMED Atlas, 2004

    e) An upper mantle conductive feature is apparent

    north of the Betics Front

    f) Increasing depth of electric LAB towards north

    LithosphereLithosphere

    a

    the Betic Chain, the latter formed

    as a consequence of the

    convergence between the African Change in complexity

    f) Increasing depth of electric LAB towards north

    is in agreement with seismic models

    g) The eLAB beneath the Tajo Basin appears to be

    Acknowledgements

    convergence between the African

    and Iberian plates since late

    Cretaceous time (60 My)

    Change in complexity

    coincides with crust –

    lithosphere boundary

    g) The eLAB beneath the Tajo Basin appears to be

    deeper than previously assumed (>150 km)AcknowledgementsCretaceous time (60 My)

    • The Betic Chain can be subdivided

    in External zone (non-

    • The authors would like to acknowledge the financial

    support by the Science Foundation Ireland (SFI)

    Great thanks goes o all the fantastic members of theStrike direction vs. RMS errorDimensionality analysisin External zone (non-

    metamorphosed rocks, Triassic to

    Neogene) and Internal zone

    (metamorphic rocks, mainly

    • Great thanks goes o all the fantastic members of the

    phase I and II fieldwork teams and the good souls helping

    during the processing

    Strike direction vs. RMS errorBetics Tajo Basin

    Dimensionality analysisBetics Tajo Basin

    External Internal External InternalNN SS

    (metamorphic rocks, mainly

    Paleozoic)

    • Structures in the Betics have

    during the processingGeoelectric strike

    direction is dominated

    by the structures above 2D:

    1D:

    References• Structures in the Betics havepreferred ENE orientation

    ― Internal zone: Antiformal-• Chave, A.D. and Thomson, D.J. 2004. Bounded influence estimation of

    by the structures above

    30 km

    � 40.4 degrees

    3D/2D:

    3D:

    2D:

    ― Internal zone: Antiformal-

    synformal relief, related to tectonic

    structures active since the Late

    • Chave, A.D. and Thomson, D.J. 2004. Bounded influence estimation of

    magnetotelluric response functions, GJI 157, p.988-1006

    • Egbert, G. 1997. Robust multiple-station magnetotelluric data processing. GJI 130,

    p.475–496

    • Martí, A, Queralt, P. and Ledo, J. 2009. WALDIM: A code for the dimensionality

    � 40.4 degrees

    (av. RMS = 1.3)3D:

    structures active since the Late

    Miocene.

    ― External zone: Fold-and-thrust

    • Martí, A, Queralt, P. and Ledo, J. 2009. WALDIM: A code for the dimensionality

    analysis of magnetotelluric data using the Rotational Invariants of the Magnetotelluric

    Tensor

    Martí, A., Queralt, P., Roca, E., Ledo, J. And Galindo-Zaldivar, J. 2009. Geodynamic Highly complex 3D subsurface

    Using Strike by McNeice and Jones, 2001 Chosen strike direction of 40o fits data better in the

    Tajo Basin than in the complex Betics area

    Using WALdim by Marti et al., 2009

    Processing

    ― External zone: Fold-and-thrust

    belts

    Martí, A., Queralt, P., Roca, E., Ledo, J. And Galindo-Zaldivar, J. 2009. Geodynamic

    implications for the formation of the Betic-Rif orogen from magnetotelluric studies,

    JGR 114, B01103

    • McNeice, G. and Jones, A.G. 2001. Multisite, multifrequency tensor decompositionEnhanced recording

    Tajo Basin than in the complex Betics area

    Processing

    FieldworkNew design of LVIV long-period system, with separate recording

    of each telluric channel, allowed for advanced data processing

    • McNeice, G. and Jones, A.G. 2001. Multisite, multifrequency tensor decomposition

    of magnetotelluric data. Geophysics 66 p.158-173.

    • Platt, J.P. 2007. From orogenic hinterlands to Mediterranean-style back-arc basins: a

    comparative analysis J. Geol. Soc. 164, p. 297–311

    Teixell, A., Ayarza, P., Zeyen, H., Fernandez, M. and Arboleya, M.-L. 2005. Effects of

    • Broadband MT data with robust processing algorithm by Gary Egbert, 1997

    • Long period MT data with Birrp by Alan Chave and D. Thomson, 2004

    Enhanced recording

    Fieldwork

    • Duration Sep.-Nov. 2007

    • ~ 400 km profile

    of each telluric channel, allowed for advanced data processing Teixell, A., Ayarza, P., Zeyen, H., Fernandez, M. and Arboleya, M.-L. 2005. Effects of mantle upwelling in a compressional setting: the Atlas Mountains of Morocco. Terra

    Nova, 17, p.456-461

    • The TRANSMED Atlas: The Mediterranean Region from Crust to Mantle. Cavazza, W.,

    • Long period MT data with Birrp by Alan Chave and D. Thomson, 2004

    • D+ correction in WinGLink

    • Dimensionality analysis with WALdim by Anna Marti et al., 2009North

    November, 2007

    Comparison of the two channels

    recording north to ground (red) and• ~ 400 km profile

    • 25 Phoenix broadband MT stations

    • 20 LVIV long-period MT station

    • The TRANSMED Atlas: The Mediterranean Region from Crust to Mantle. Cavazza, W.,

    Roure, F., Spakman, W., Stampfli, G.M., Ziegler, P.A. (Eds.) 2004. Springer-Verlag. Berlin

    Heidelberg Germany

    • WinGLink User’s Guide, version 2.07.04. Geosystems SRl 2004. Milan, Italy

    • Dimensionality analysis with WALdim by Anna Marti et al., 2009

    • Strike analysis and tensor decomposition with Strike by McNeice and Jones, 2001

    • 2D sharp boundary and smooth Inversion with WinGLink

    North

    Average

    South

    recording north to ground (red) and

    south to ground (green) and their

    average (blue) revealing that the

    southern electrode was disturbed.

    Using the electric data recorded by• 20 LVIV long-period MT station • WinGLink User’s Guide, version 2.07.04. Geosystems SRl 2004. Milan, Italy• 2D sharp boundary and smooth Inversion with WinGLinkUsing the electric data recorded bythe north to ground channel yieldsbetter MT responses