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Drab Laureen

tel : 01 44 32 22 17

Doctorante - Ecole normale supérieure

Contact : Laureen Drab

Thème de recherche
Paléosismologie, tectonique active et géomorphologie

Encadrants
Aurélia Hubert-Ferrari

Résumé du sujet
During my PhD, I worked on paleoseismology, geomorphology and active tectonic under the direction of Professor Aurélia Hubert-Ferrari at the Geology Laboratory of Ecole Normale Supérieure in Paris in collaboration with Julie Carlut (ENS (Ecole Normale Sup-erieure), Paris, France), Lucillia Benedetti (CEREGE (Centre Européen de Recherche et d’Enseignement des Géosciences de l’Environnement), Aix en Provence, France), Jérôme Van derWoerd (EOST (Ecole et Observatoire des Sciences de la Terre), Strasbourg, France) and Sabine Schmidt (EPOC (Environnements et Paléoenvironnements OCéaniques), Bordeaux, France). I will defend my PhD thesis in October 2011.

My PhD work is divided in two parts. The first one deals with geomorphology and tectonic in the central part of the North Anatolian Fault situated in Turkey. There, I mapped three terraces preserved in two pull-aparts and incised by the longest river in Turkey : the Kizilirmak River.
The main results of this work are several constraints on the ages of the terraces using 10Be, 26Al, and 36Cl cosmogenic dating methods. Moreover, I measured 10Be on sand coming from river beds to get past to actual erosion rates along the Kizilirmak river as well as present erosion rate from small rivers flowing to the West (Collaboration with Lucilla Benedetti (CEREGE, Marseille, France) and Jérôme Van Der Woerd (IPG, Strasbourg, France)). The obtained in situ cosmogenic 36Cl exposure ages calculated are 22ka for the lowest terrace, 6-80ka for the middle terrace, and 10-120ka for the highest terrace in the areas preserved from erosion. The highest terrace shows a contribution of younger ages due to erosion of the nearby limestone catchment. The obtained results imply a climatic origin of the terraces, and an incision rate of about 1mm/yr along the Kizilirmak.

The second part focuses on obtaining a new paleoseismological record of earthquakes in the Marmara Sea (West of Turkey) using di-erent analysis to pinpoint and characterize earthquake-related sedimentary disturbance in the cores I studied.
I seek to provide a spatio-temporal understanding of earthquakes in the Marmara Sea allowing greater insight into long-term fault behavior and seismic interaction by integrating historical and new paleosismological data (reccurence rate in the Sea of Marmara). I characterized earthquake-related sedimentary events by combining X-ray imagery, magnetic susceptibility, granulometry, TOC and XRF (chemical analyses) measurements. Major sedimentary events can be traced between basins.
I also aim at establishing a reliable and robust chronology of the cores combining radiocarbon dating (bulk sedimentation, foraminifers, shelves) and recorded magnetic variations (remanence, saturation of magnetization, magnetic mineralogy, paleodirection and paleointensity). The radiocarbon dating does not produce very reliable data, but can help to better constrain core correlation in and between basins using, in addition, lead results for the sedimentation rate in the top of cores (collaboration with Sabine Schmidt, EPOC, Bordeaux, France). The downcore changes in magnetic properties suggest taking into account possible delays in the acquisition of magnetization (early diagenesis) (collaboration with julie Carlut, ENS, Paris).

Parcours

Master Recherche Géologie et risques naturels à l’institut de Physique du globe. Mention B. stage sur le transport par charge de fond avec François Métivier.
Licence STEP, paris 7 mention AB

Enseignements
Geomorphology (M1 with P. Meunier) (2009, 2010)
Introduction to Geology (L1 in Paris 6) (2009, 2010)
Field geomorphology (M1 with P. Meunier) (2010)
Geophysical fields (L3 with C. Vigny) (2009)

Bibliographie