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 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