EMSEV-DEMETER JOINT WORKSHOP IGAR September 7-12, 2008 Bucharest - - PowerPoint PPT Presentation

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EMSEV-DEMETER JOINT WORKSHOP IGAR September 7-12, 2008 Bucharest SINAIA, ROMANIA GEODYNAMIC TORSION PROCESS OF THE GEODYNAMIC TORSION PROCESS OF THE SEISMOGENIC RELIC SLAB AND THE SEISMOGENIC RELIC SLAB AND THE INTERMEDIATE DEPTH SEISMICITY

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GEODYNAMIC TORSION PROCESS OF THE GEODYNAMIC TORSION PROCESS OF THE SEISMOGENIC RELIC SLAB AND THE SEISMOGENIC RELIC SLAB AND THE INTERMEDIATE DEPTH SEISMICITY OF THE INTERMEDIATE DEPTH SEISMICITY OF THE VRANCEA ZONE VRANCEA ZONE

Dumitru STANICA and Maria STANICA Dumitru STANICA and Maria STANICA

EMSEV-DEMETER JOINT WORKSHOP IGAR

September 7-12, 2008 Bucharest SINAIA, ROMANIA

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OUTLINE: OUTLINE:

SEISMIC ACTIVE VRANCEA ZONE; GEOTECTONIC SEISMIC ACTIVE VRANCEA ZONE; GEOTECTONIC OVERVIEW: OVERVIEW:

  • CRUSTAL MAP (Sandulescu and

CRUSTAL MAP (Sandulescu and Visarion Visarion, 2000); , 2000);

  • DEEP GEODYNAMIC MODELS:

DEEP GEODYNAMIC MODELS:

1. 1.

Wenzel et al., 1998: CRC (Germany)+ RGVE (Romania) groups; Wenzel et al., 1998: CRC (Germany)+ RGVE (Romania) groups;

2. 2.

Linzer Linzer, PANCARDI, 2000; , PANCARDI, 2000;

3. 3.

Sperner Sperner et al., 2005; et al., 2005;

4. 4.

Martin et al., 2006 Martin et al., 2006

5. 5.

Zadeh Zadeh, 2005 , 2005

THE ELECTRICAL CONDUCTIVITY ANOMALY THE ELECTRICAL CONDUCTIVITY ANOMALY -

  • TRANSEUROPEAN SUTURE ZONE AND ACTIVE FAULTS

TRANSEUROPEAN SUTURE ZONE AND ACTIVE FAULTS (ELECTROMAGNETIC DATA) (ELECTROMAGNETIC DATA): :

1. 1.

CEMES (Central Europe Mantle CEMES (Central Europe Mantle geoElectrical geoElectrical Structures) NATO Structures) NATO-

  • Project (2001

Project (2001-

  • 2003) :

2003) :

  • 1D and 2D

1D and 2D lithospheric lithospheric resistivity models; resistivity models;

  • 3D images w ith mantle conductance distribution

3D images w ith mantle conductance distribution

2. 2.

Lithospheric Lithospheric peculiarities on the Romanian territory: peculiarities on the Romanian territory:

  • 1D, 2D models (including resistivity/phase response functions)

1D, 2D models (including resistivity/phase response functions)

  • 3D tomographic images;

3D tomographic images;

3. 3.

Carpathian electrical conductivity anomaly Carpathian electrical conductivity anomaly

4. 4.

TransEuropean TransEuropean Suture Zone (TESZ) Suture Zone (TESZ)

5. 5.

Geodynamic model Vrancea zone Geodynamic model Vrancea zone

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GEOTECTONIC OVERVIEW GEOTECTONIC OVERVIEW

CRUSTAL MAP (Sandulescu and CRUSTAL MAP (Sandulescu and Visarion Visarion, 2000) , 2000)

Vrancea zone

  • 1. Precambrian East European

Platform crust;

  • 2. Precambrian Moesian Platform

crust;

  • 3. Paleozoic Scythian Platform

crust;

  • 4. Cimmerian-North Dobrogea

crust;

  • 5. “Transylvanian” type crust;
  • 6. “Pannonian” type crust;
  • 7. Depth to Moho;
  • 8. Main deep faults (mostly

transcrustal);

  • 9. Position of the suture zones at

the Moho level ;

  • 10. Seismic active Vrancea zone
  • 11. Magnetotelluric profiles
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Deep Geodynamic Models Deep Geodynamic Models-

  • Vrancea zone

Vrancea zone

Wenzel et al., 1998 CRC (Germany)+ RGVE (Romania) groups

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DEEP GEODYNAMIC MODELS DEEP GEODYNAMIC MODELS

Wenzel et al., 1998: CRC (Germany)+ RGVE (Romania) groups Wenzel et al., 1998: CRC (Germany)+ RGVE (Romania) groups

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DEEP GEODYNAMIC MODELS DEEP GEODYNAMIC MODELS

Wenzel et al., 1998: CRC (Germany)+ RGVE (Romania) groups Wenzel et al., 1998: CRC (Germany)+ RGVE (Romania) groups

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DEEP GEODYNAMIC MODELS DEEP GEODYNAMIC MODELS

HYPOTHETICAL LITHOSPHERIC CROSS - SECTION SHOWING THE CONCENTRATION OF EARTHQUAKES IN THE VRANCEA AREA AND THEIR RELATIONSHIP TO A SINKING SLAB IN THE UPPER MANTLE (Linzer, PANCARDI, 2000)

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DEEP GEODYNAMIC MODELS DEEP GEODYNAMIC MODELS

Gvirtzman, 2003

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DEEP GEODYNAMIC MODELS DEEP GEODYNAMIC MODELS

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DEEP GEODYNAMIC MODELS DEEP GEODYNAMIC MODELS

Top: Bottom :

(Sperner et al., 2005) (Martin et al., 2006)

Geodynamic evolution of plate

subduction in SE Romania since the late Miocene (12 Mil.years ago) Tomographic image of the subducted slab as high velocity body viewed from SSW

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SLIDE 11

Alik Ismail Zadeh, 2005

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TESZ TESZ -

  • Electromagnetic data

Electromagnetic data

CEMES (Central Europe Mantle CEMES (Central Europe Mantle geoElectrical Structure) NATO geoElectrical Structure) NATO-

  • Project

Project

  • B. Deep Electromagnetic Soundings of
  • B. Deep Electromagnetic Soundings of

the Mantle around the TESZ the Mantle around the TESZ

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TESZ TESZ -

  • Electromagnetic data

Electromagnetic data

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TESZ TESZ -

  • LITHOSPHERIC PECULIARITIES ON THE ROMANIAN

LITHOSPHERIC PECULIARITIES ON THE ROMANIAN TERRITORY : TERRITORY : 2D MT models and response functions 2D MT models and response functions

DEPTH[Km]

2D-tomographic image ( ) along the blue line (Dobrogean Orogen) perpendicular to the Peceneaga-Camena (P-C) active fault ρ

Resistivity response

  • f the 2D model
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SLIDE 15

2D MT models and 3D tomographic images 2D MT models and 3D tomographic images

PHASE DISTRIBUTION (B-POLARIZED MODE) PHASE DISTRIBUTION (E-POLARIZED MODE)

P

  • C

F P

  • C

F

l TULNICI l PANCIU l ESE SW WNW NE l
  • TG. SECUIESC
l FALCIU

TROTUS F TROTUS F

RELIC SLAB RELIC SLAB

WNW
  • TG. SECUIESC
l l l l TULNICI PANCIU ESE SW FALCIU l 0.3 - 0.5 - 1.0 - 2.0 - 3.0 - 5.0 - 10.0 - 20.0 - 30.0 - 0.3 - 0.5 - 1.0 - 2.0 - 5.0 - 10.0 - 20.0 - 30.0 - SQRT(T) SQRT(T) NE

C E C A C E C A

2 D MODEL VRANCEA Z ONE

Profile :

Cata lina - Tulnici - Panciu (Forw ard modeling-finite e le ment code)

3D magnet otelluric t omographic image in t he Vrancea zone on the 3-50km depth int er val; green plane is t he Peceneaga-Camena fault; blue plane is the Trotus fault .

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Carpathian Electrical Conductivity Anomaly (CECA) Carpathian Electrical Conductivity Anomaly (CECA)

CONTINENTAL LITHOSPHERE- PHANEROZOIC TERRANES (Transylvanian Basin)

  • 120
  • 100
  • 80
  • 60
  • 40
  • 20

200 400 600 800 RESISTIVITY (ohm .m ) DEPTH (km) Series1

CONTINENTAL LITHOSPHERE - THE EUROPEAN PLATFORM

  • 250
  • 200
  • 150
  • 100
  • 50

200 400 600 800 1000 1200 RESISTIVITY (ohm.m) Depth (km) Series1

40 60 80 100 120 140 160 180 200 220 20 40 60 80 100 120 140

3 44 21 12 5 2 2 7 2 15 52 22 42 7 23 20 4 16 42 111 36 394 15 5 3 26 13 5 4 219 56 88

Brasov

Focsani Buzau

E P Resistivity distribution at 100km depth Resistivity distribution at 100km depth

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TESZ TESZ TESZ TESZ -

  • LITHOSPHERIC PECULIARITIES ON THE

LITHOSPHERIC PECULIARITIES ON THE LITHOSPHERIC PECULIARITIES ON THE LITHOSPHERIC PECULIARITIES ON THE ROMANIAN TERRITORY ROMANIAN TERRITORY ROMANIAN TERRITORY ROMANIAN TERRITORY : : : : MT MT MT MT Data Data Data Data

20 21 22 23 24 25 26 27 28 29 30 43 44 45 46 47 48 49

18 - 28 km 30 - 38 km 40 - 50 km

80 160 240 320km

BRITTLE-DUCTILE TRANSITION ZONE IN THE LOWER CRUST

TESZ EAST EUROPEAN PLATE

MOESIAN PLATE INTRA-ALPINE PLATE

VRANCEA ZONE

Stanica, Stanica Stanica, Stanica -

  • 1999, 2001

1999, 2001

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Magnetotelluric tomography (resistivity) at 100 km depth Magnetotelluric tomography (resistivity) at 100 km depth

EP EP -

  • European Platform;

European Platform; w hite diamonds w hite diamonds -

  • Trans

Trans-

  • European Suture Zone;

European Suture Zone; blue cross blue cross-

  • w ises

w ises -

  • Pecenaga

Pecenaga-

  • Camena

Camena fault; fault; w hite rectangle w hite rectangle -

  • horizontal cross

horizontal cross-

  • section through the relic slab.

section through the relic slab.

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Magnetotelluric tomography (resistivity) at 150 km depth. Magnetotelluric tomography (resistivity) at 150 km depth.

EP EP -

  • European Platform;

European Platform; White rectangle White rectangle

  • horizontal cross

horizontal cross-

  • section through the relic slab.

section through the relic slab.

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Deep Geodynamic Model (50 Deep Geodynamic Model (50 -

  • 150km)

150km) -

  • Vrancea zone

Vrancea zone

MT MT-

  • TOMOGRAFIES

TOMOGRAFIES -

  • torsion process of the relic slab

torsion process of the relic slab

Stanica et al., 2004

Descending Asthenospheric Currents

GEO-MOTION GROUP

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Geodynamic model Geodynamic model-

  • Vrancea zone

Vrancea zone

Geodynamic model elaborated beneath the crustal level. The thick black lines represent CECA; yellow circles are intermediate depth earthquakes(Stanica et al., 2004)

INTERMEDIATE DEPTH EQ INTERMEDIATE DEPTH EQ hypocenters hypocenters epicenters epicenters MoP

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SUMMARY: SUMMARY:

The inferred torsion that may result from the effects The inferred torsion that may result from the effects due to descending asthenospheric currents, on one hand, due to descending asthenospheric currents, on one hand, and to the irregular shape of the relic slab on the other, is and to the irregular shape of the relic slab on the other, is capable, in our opinion, of generating a torque that may capable, in our opinion, of generating a torque that may increase shear stress and drive faulting and re increase shear stress and drive faulting and re-

  • shear

shear within the rigid slab. within the rigid slab. If this is the case, then the triggering of the If this is the case, then the triggering of the intermediate intermediate-

  • depth earthquakes, in the Vrancea zone, may

depth earthquakes, in the Vrancea zone, may be interpreted as the rock response to active be interpreted as the rock response to active torsional torsional processes sustained by a counterclockwise rotation of processes sustained by a counterclockwise rotation of the slab which is induced by the complex interplay among the slab which is induced by the complex interplay among the threefold structure of the lithosphere, in this sector of the threefold structure of the lithosphere, in this sector of the Eastern Carpathians, and the surrounding the Eastern Carpathians, and the surrounding asthenosphere asthenosphere. .

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Acknowledgments: Acknowledgments:

This study is supported by the Ministry of This study is supported by the Ministry of Education and Research, National Program Education and Research, National Program “ “PN2 PN2” ”, Contract No.31 , Contract No.31-

  • 018/2007

018/2007-

  • 2010

2010

THANK YOU ! THANK YOU !