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: jschmoldt@cp.dias.ie

Motivation Phase IPhase II

Tectonic 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, 2007

Inversion parameters2D Inversion Resultstructures 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 populated

fieldwork 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 station

Lithosphere

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 Internal NN 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 have

preferred 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 by

the north to ground channel yields

better MT responses