Côme Lefebvre

 

Aladağ mountains, view from the summit of Mt Emler (3723m)

 

 

Professional appointments

2012 – present  Postdoctoral Associate

University of Minnesota (CD-CAT project)

 

2011 – 2012  Research and Teaching Assistant

Université de Nice – Sophia Antipolis (Dynamic of orogens group)

Education

Ph.D. in Geology (2011), Utrecht Universiteit

Ph.D. dissertation title:  ‘The tectonics of the Central Anatolian Crystalline Complex: a structural, metamorphic and paleomagnetic study’

 

M.Sc. in Geology (2007), Université Montpellier 2

M.Sc. thesis title: ‘Mantle exhumation mechanisms:  Contribution from the study of micro-textures and the deformation of serpentinites of a Corsican ophiolite'

 

B.Sc. in Geology (2005), Ecole Normale Supérieure (Lyon)

 
 

Broad research interests

      My interests in Earth Sciences range across the fields of structural geology, metamorphic petrology and tectonics with links to geochronology, geophysics and geochemistry. The central theme of my research is the application of field and laboratory studies to unravel some aspects of mountain belt evolution, near tectonic plate boundaries, through the investigation of rock deformation as well as metamorphic and magmatic processes.

 

       For the past six years, my work mostly concentrates on the Anatolian segment of the Alpine-Himalayan orogeny, located more specifically in central and south-east Anatolia (see map).

 

 

Morpho-tectonic map of the Eastern Mediterranean region (the gray polygon indicates my main area of investigation)

Current research

       Currently, the heart of my research is taking place in the tectonically and volcanically active region where the Arabian, Eurasian and Anatolian plates meet together in SE Turkey. My work is part of a large interdisciplinary project entitled CD-CAT (for Continental Dynamics - Central Anatolian Tectonics). The aim of this project is to investigate surface-to-mantle dynamics in context of subduction to collision transition between the Arabian/Eurasian plates, westward escape of Anatolia and ultimately plateau formation during the Neogene.


       My contribution to this great enterprise consists in tracking and evaluating regional vertical motion that occurred during collision and was associated or not with the major faults from the area (e.g. the Central Anatolian Fault Zone, the Malatya Fault Zone, the Sürgü Fault Zone and the East Anatolian Fault Zone) using a combination of field structural data and mapping together with low-temperature thermochronological techniques such as (U-Th)/He and fission track on apatites and fission track on zircons.

 

 

Projects in Anatolia

          The tectonics of the Kırşehir Massif or Central Anatolian Crystalline Complex (CACC): the largest metamorphic massif in Turkey that covers a triangular domain of ~250x250x250km located in central Anatolia. The CACC mostly consists of metamorphic rocks, ophiolites and magmatic intrusions that reflect of a complex tectonic history involving obduction of ophiolitic nappes onto Paleozoic-Mesozoic sedimentary units, development of a regional Barrovian metamorphism, and widespread magmatic intrusions occurring during late Cretaceous in context of closure of Neotethyan ocean(s) between the converging African and Eurasian continents.

       My motivation to conduct research in this area is to try to reach and propose a consensus about the  geodynamic scenario in which the CACC evolved during the end of the Cretaceous.
To do so, I focus on reconciling the tectono-metamorphic history of the central Anatolian metamorphic rocks through large-scale mapping of ductile structures and metamorphic field gradients together with detailed microstructural, metamorphic and geochronological analysis, and paleomagnetic investigations carried on upper Cretaceous granitoids.

       The main results revealed that during the late Cretaceous the CACC consisted of an elongated dome-shaped structure (~500x150km) oriented NNE-SSW (see restoration above). In this configuration, regional Barrovian metamorphism was accompanied with a top-to-the-SSW ductile crustal flow in the deeper part of the dome, while shallower levels were synchronously affected by a WNW-ESE directed exhumation. Post-tectonic magmatism affecting the western side of the dome shows a geochemical evolution from calc-alkaline to alkaline (from west to east). This magmatic trend together with HT-LP metamorphic conditions and the restored configuration of the CACC is recognized as typical of a magmatic arc setting in a supra-subduction environment.

       Finally, during the Paleogene, the collision of the NNE-SSW-oriented magmatic arc with the central Pontides led to the break-up of the CACC into three distinctive domains as exposed today (see figure above).

 

 

Publications

Lefebvre, C., Peters, M.K., Wehrens, P.C., Brouwer, F.M., van Roermund, H.L.M., 2015, Thermal history and extensional exhumation of a high-temperature crystalline complex (Hırkadağ Massif, Central Anatolia), Lithos, DOI:10.1016/j.lithos.2015.09.021

 

Lefebvre, C., 2015, Comment on 'Late Cretaceous extension and Palaeogene rotation-related contraction in Central Anatolia recorded in the Ayhan-Büyükkışla basin' by Advokaat et al., 2014, International Geology Review,  DOI:10.1080/00206814.2015.1025242

 

Lefebvre, C., Meijers, M. J. M., Kaymakci, N., Peynircioglu, A., Langereis, C. G. and van Hinsbergen, D. J. J., 2013, Reconstructing the geometry of central Anatolia during the late Cretaceous: Large-scale Cenozoic rotations and deformation between the Pontides and Taurides, Earth and Planetary Science Letters, 366, 83-98, DOI:10.1016/j.epsl.2013.01.003

 

Gülyüz, E., Kaymakci, N., Meijers, M. J. M., van Hinsbergen, D. J. J., Lefebvre, C., Vissers, R., Hendriks, B. and Peynircioglu, A. A., 2013, Late Eocene evolution of the Çiçekdağı Basin (central Turkey): Syn-sedimentary compression during microcontinent–continent collision in central Anatolia, Tectonophysics, 602, 286-299

 

Lefebvre, C., Barnhoorn A., van Hinsbergen, D. J. J., Kaymakci, N., Vissers, R., 2012, Reply to Genç and Yürür's comments on: "Late Cretaceous extensional denudation along a marble detachment fault zone in the Kırşehir massif near Kaman, central Turkey", Journal of Structural Geology, 36, 90-93

 

Lefebvre, C., Barnhoorn A., van Hinsbergen, D. J. J., Kaymakci, N., Vissers, R., 2011, Late Cretaceous extensional denudation along a marble detachment fault zone in the Kırşehir massif near Kaman, central Turkey", Journal of Structural Geology, 33(8), 1220-1236

http://www.researchgate.net/profile/Come_Lefebvre/

 

 

Courses taught

2012 (Université de Nice - Sophia Antipolis):

- Metamorphic processes (graduate level)

- Stratigraphy / Paleontology (under-graduate level)

 

Teaching assistance

2008-2010: Practicals with 2nd year students (Utrecht University):

- "Deformation and Metamorphism of the crust"

2008-2010: Fieldwork with 2nd year students:

- "Excursion through the Pyrenean Axiale Zone" (Spain)

- "Analysis of deformed and metamorphosed rock: Field exercise" in Cap de Creus - Cadaquès (Spain)

 

Student supervision

2010: Eldert Advokaat (Master student), "Tectono-stratigraphic evolution of the Ayhan basin, central Anatolia, Turkey: a late Cretaceous to early Eocene supra-detachment basin that underwent post-Lutetian compression and tilting" - Utrecht University

2009: Kalijn Peters (Master student), “Metamorphic evolution of the Hırkadağ and Kırşehir massifs (Central Turkey) based on geothermobarometry of HT metapelitic rocks” - Utrecht University

2008: Philip Wehrens (Master student), “Structural evolution of the Hırkadağ massif, Central Anatolian Crystalline Complex, Turkey” - Utrecht University

 

 

Contact:

Côme Lefebvre

Postdocoral Associate

310 Pillsbury Drive SE

Dept of Earth Sciences

University of Minnesota

Minneapolis MN 55455 USA

Tel  +1 612 624 8557

@mail: lefebvre at umn.edu