N-S Ext.

MANTLE DYNAMICS

UPLIFT – Dynamic topography EXTENSION – Surface velocityN S

B-2

THER

MA

L STRU

CTU

RE

based

on

tom

ograp

hic

inversio

n

C-1 like B-2 with density

contrast between mantle

lithosphere (3240 kg/m3)

and asthenosphere (3340

kg/m3)

INTRODUCTION

Western Anatolia is stretching in the

north-south direction and its hot crust

(Tezcan & Turgay, 1991) is thinning.

On the other hand, high Bouguer

gravity values (Özelçi, 1973), marine

and river terraces, and positive residual

and dynamic topography suggest that

the area is rising (despite the stretching).

EXTENSION IS N-S

It can be postulated that pull of the attached

part (western) of the subducting African slab

(van Hinsbergen et al., 2010) can generate

SW-NE extensional deformation in Western

Anatolia and coherent southwestward motion

of Anatolia. However, the extension

in the region is almost pure N-S on

that SW moving block based on GPS

measurements (E.g., McClusky et al., 2000).

According to seismic tomographic

inversions (E.g., van Hinsbergen et al.,

2010), the subducted slab beneath the south

of Western Anatolia seems to be detached

from the African plate and hence

may not generate a strong southward

slab-pull force. Thus, it can not pull

Western Anatolia to stretch in N-S direction.

The residual topography map

(Komut et al., 2012) was

regenerated using estimates from

Tezel et al. (2013) and CRUST 1.0

model based on lateral changes

(continental / oceanic) for crust

and sea water load. The

anomalous residual topography

(red tones) may be related to

underlying mantle dynamics.

The concurrent N-S crustal

deformation (stretching) may be

important too, and has not been

considered in previous studies.

We model mantle flow in conjunction with active crustal deformation to explain the

tectonics in the region. There is a good correlation between residual topography and

dynamic toporaphy plots. The numerical experiments suggests:

- more than 1 km of the observed topography is related to dynamic support of underlying

mantle in Western Anatolia.

- Dynamic topography anomaly has a plateau pattern if we use temperature data (ΔT)

rather than normal geotherm for the base of the lithospheric layer (Exps.: B).

- Comparison of plateau type dynamic topography anomaly of plots of B-1 and B-2

suggests that crustal geotherm is driven by asthenospheric hot temperature beneath

Anatolia. No similar pattern in plots A type experiments because of their isolated crust

(793 K constant temperature for base of the crust).

- Generated surface velocity field eminently supply velocities measured by GPS (See

Aktug et al., 2009) along the profile that is parallel to the stretching direction (N-S).

- C-1 experiment which assumes stronger mantle (weaker mantle lithosphere) provide a

good fit for surface velocities.

REFERENCESAktug, B., Nocquet, J. M., Cingöz, A., Parsons, B., Erkan, Y., England, P., Lenk, O., Gürdal, M. A., Kilicoglu, A., Akdeniz, H. & Tekgül, A. (2009). Deformation of western Turkey from a combination of permanent and campaign GPS data: Limits to block-like behavior. JGR, 114, B10404. doi:10.1029/2008JB006000

Amaru, M. L. (2007). Global travel time tomography with 3-D reference models, PhDthesis, Utrecht Univ., Utrecht, Netherlands.

Göktürkler, G., Salk, M. & Sari, C. (2003). J. Balkan Geophys. Soc., 6, 1, 1-15.

Komut, T. (1998). A Review of the Tectonics of the Aegean Region, M.S. Thesis, BoğaziçiÜniversitesi, İstanbul, Turkey, 254p.

Komut, T., Gray, R., Göğüş, H. O. & Pysklywec, R. N. (2012). Mantle Flow Uplift of Western Anatolia and the Aegean: Interpretations from Geophysical Analyses and Geodynamic Modeling. J. Geophys. Res., 117, B11412, doi:10.1029/2012JB009306

McClusky, S. & Balassanian, S. & Barka, A. & Demir, C. & Ergintav, S. & Georgiev, I. & Gurkan, O. & Hamburger, M. & Hurst, A. & Kahle, H. & Kastens, K. & Kekelidze, G. & King, R. & Kotzev, V. & Lenk, O. & Mahmoud, S. & Mishin, A. & v. d. (2000). Global positioningsystem constraints on plate kinematics and dynamics in the eastern Mediterranean andCaucasus, Journal of Geophysical Research, 105, B3, 5695-5720.

Özelçi, H. F. (1973). Doğu Akdeniz gravite anomalileri. Maden Tetkik ve Arama Dergisi, 80, 54-89.

Tezcan, A. K. & Turgay, M. I. (1991). Heat flow and temperature distributions in Turkey, in Cermak, V., Haenal, R., & Zui, V., Eds., Geothermal Atlas of Europe: Herman HAACKVerlag, Gotha, Germany.

Tezel, T., Shibutani, T. & Kaypak, B. (2013). Crustal thickness of Turkey determined byreceiver function. J. Asian Earth Sci., 75, 36-45. doi: 10.1016/j.jseaes.2013.06.016

van Hinsbergen, D. J. J., N. Kaymakci, W. Spakman, & T. H. Torsvik (2010). Reconciling the geological history of western Turkey with plate circuits and mantle tomography, EarthPlanet. Sci. Lett., 297, 674–686, doi:10.1016/j.epsl.2010.07.024

time for modelling: 63376 yr

CONCLUSION

N-S extension (~20 mm/yr) of the crust in the

models was driven by mantle circulation based

on a thermal structure derived from seismic

tomography profiles for the region. In general,

instead of using assumptions using observed

data, such as converted temprature structure

of crust from heat flow and reliable crustal and

geothermal structures, for model inputs causes

better results. We compare the dynamic

topography results with residual topography

based on crustal models interpreted from

recent receiver function studies. A good

correlation suggests that the diffuse lateral N-S

extensional deformation of the crust in

Western Anatolia has been generated

by convection of the asthenosphere, which

also results in considerable uprising

of the surface topography of the crust.

N-S extension(GPS velocity)

ANATOLIA

ANATOLIAANATOLIA

ANATOLIA

Tolga KOMUT1, Russell PYSKLYWEC2, Ebru ŞENGÜL ULUOCAK1

1. Department of Geophysical Engineering, Faculty of Engineering, Çanakkale Onsekiz Mart University, Çanakkale, Turkey2. Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada

N-S Ext.

After McClusky et al., 2000

N-S Ext.

After Komut, 1998

MODEL SET-UP & SELECTED EXPERIMENTSMantle flow models are based on a thermal

structure derived from a P-wave seismic

tomography section (See, van Hinsbergen et al.,

2010; Amaru, 2007). Using various

combinations of rheological and mechanical

parameters, we systematically designed and

carried out more than a thousand experiments.

The modeling is notable also because it uses

temperature values (Göktürkler et al., 2003)

converted from heat flow data for the crust of

Western Anatolia (See, Experiment B-2)

which is characterized by high heat flow.

Values in boxes arethicknesses in km

N SANATOLIA

2 4 6 8 10 12 14degree

0

Location is shown on residual topography map.

m