Description du sujet de thèse

Reconstructing the Eocene paleoclimate of southern Eurasia via geological and geochemical proxies to better understand past mammalian dispersals.
The late Eocene and early Oligocene are paced by multiple dispersal events of Asian mammals to Europe, Africa, up to south America, including anthropoid primates. However, the mechanisms controlling these dispersals are poorly understood.
Eocene primates and many other mammals involved in these dispersals used to thrive in the tropics. Their dynamics of expansion must thus have closely mimicked the spreading of tropical ecosystems. This PhD project proposes to reconstruct the paleoclimatic evolution along the dispersal pathways to understand how changing climatic parameters (rainfall amount, temperatures, both annual and seasonal) favored or dampened the development of these ecosystems.
The project will specifically focus on sites along the Paleogene Neotethyan shorelines in southern Eurasia, the most likely dispersal pathway for Asian mammals to reach Europe and Africa. We will particularly work on Anatolian and central Asian localities, where paleoclimatic data are lacking. The PhD student will use various geological and geochemical proxies to study the regional paleoclimate evolution. Sites will be first dated using two complementary approaches: U-Pb dating of volcanic material and magnetostratigraphy. Climatic parameters will then be reconstructed using a combination of qualitative (sedimentary facies reconstruction) and quantitative (geochemical) approaches, including stable and clumped isotopic analysis of various types of organic and inorganic material.
The ERC project DISPERSAL aims at studying and modeling past mammalian dispersals, using as a type-example the dispersal of rodents and primates from Asia to South America 40 to 35 million years ago. We hire a PhD student to reconstruct the regional paleoclimatic evolution associated with these dispersal events, using various geological and geochemical proxies.
The PhD student will participate to the fieldtrips of the ERC project DISPERSAL (in Turkey, Central Asia and Southern Europe). He will reconstruct the paleoenvironments of key fossil sites and sections by studying their sedimentary facies, and will date the localities using a combination of geochronological (U-Pb dating of volcanic material) and magnetostratigraphic approaches. He will then reconstruct the paleoclimatic evolution using geochemical tools: stable and clumped isotopic analysis of fossils, paleosols, and organic matter. All these analyses will be done at CEREGE.

Contexte de travail

The PhD student will be work at CEREGE in Aix-en-Provence (Université d'Aix-Marseille; advisor: Alexis Licht). She/he will join a team of students, postdocs and scientists in the framework of the ERC project DISPERSAL, which aims to build a theoretical and empirical basis for the mechanisms of large-scale continental dispersal. Paleoclimatic results of the PhD project will be compared and interpreted with paleobotanical and paleontological data acquired by other members of the ERC team.

Contraintes et risques

-Risks associated with the participation to geological fieldwork.

Informations complémentaires

-Advanced knowledge in geology, sedimentology, geochemistry, paleomagnetism
-Fluent in English