JOIN US AS A DOCTORAL STUDENT (PhD)
In the GEOPS lab (University of Paris South, Paris-Saclay), a Doctorate is prepared within the SMEMAG doctoral school (Sciences Mécaniques et Energétiques, MAtériaux et Géosciences) once the candidate possesses a Masters degree or its equivalent. This three-year research programme allows the student, after the submission of a thesis, to obtain the degree of Doctor. Each year, the members of the “Paleoclimates and Sedimentary Dynamics” team propose a number of thesis topics based on research they are developing. Applications for the proposed thesis subjects are generally made in April on the doctoral school web site but do not hesitate to contact us before then to discuss and/or develop subjects that are related to the themes of the team and/or to set up collaborations or co-supervisions.
In order to give an idea of the variety of subjects proposed, and of potential national and international collaborations, please click here to access a list of subjects being studied by current PhD students and those who have recently submitted.
Over the three years of remunerated doctoral research, PhD students will have an opportunity to give tutorials within the Department of Earth Sciences and they will also be encouraged to present their work at national and international conferences, thereby establishing collaborative networks, and to attend universities and summer schools in order to further their training. To follow the experiences of our PhD students, please visit our News page.
MARGAUX B. TELLS OF HER EXPERIENCE
Photo : Julien Westhoff
“In order to learn more about the various techniques used for analysing ice cores, I attended the ICAT (Ice Core Analysis Techniques) summer school in Copenhagen from the 24th to the 29th of September, 2018. This school, organized by doctoral and post-doctoral students, provided an overview of the numerous types of analyses carried out on cores from Greenland, the Antarctic and mountain glaciers with a view to studying current and past climates. Over the course of the week, we alternated between theoretical courses, lab sessions and field outings. I was thus able to learn new things about the analysis of ice archives, be it the analysis of water, air or impurities in the cores. This summer school also gave me an opportunity to meet well-known researchers in the field of glaciology and also to exchange with other participants regarding our research work”.
RONAN J. TELLS OF HIS EXPERIENCE
« I spent most of my years in third level education at the University of Paris South. Having obtained a BSc in Earth Sciences, I undertook a Masters in “Sedimentary Basin, Resources and Paleoclimates (BSRP)”. I was lucky enough to take part in the MONOPOL oceanographic mission to the Bay of Bengal, the aim of which was to collect sedimentary cores and sea water samples in order to retrace the evolution of the South-East Asian monsoon regime over the past 180,000 years. Following this mission, I completed Masters 2 within the Paleoclimates and Sedimentary Dynamics team in collaboration with the University of Tongji (Shanghai), where I focused on erosion in the Himalayas over the past 180,000 years. After the Masters I undertook a Franco-Chinese PhD thesis on the same subject. In addition to being an enriching personal experience, this thesis allowed me to secure my current job as an Application XRF engineer with Malvern Panalytical. In fact, the scientific, linguistic and personal skills that I acquired during my third level education are at the heart of my current professional life”.
SUMMARIES OF THESES SUBMITTED BETWEEN 2015 AND 2018
Indian monsoon paleovariability and its impact on weathering of the Himalaya
Director: Christophe COLIN (GEOPS)
Funding: CSC (Chinese Scholarship Council, contingent UPSUD)
Defended July 5th, 2017
SUMMARY
The principal aims of this PhD study were to reconstruct the evolution of Asian monsoons during the Quaternary and to estimate their impact on continental erosion and land-sea sediment transfers, based on the study of marine cores collected in the Gulf of Bengal, the Arabian Sea and western part of the Philippines Sea. The scientific strategy employed involved analyses of minerals (clays), sediments (granulometry) and geochemistry (87Sr/86Sr and εNd) in order to identify sediment sources and the conditions under which erosion and sediment transfer to the ocean occurred. Analyses of lanthanide and εNd concentrations were also carried out on samples of sea water and foraminifera in order to better constrain εNd as a tracer of past oceanic circulation in a context of marked seasonal variations in inputs from Himalayan rivers. This scientific strategy allowed us, among other things, to reconstruct past changes in monsoon precipitation in the Tropical Western pacific during the Quaternary and to determine the impact of ENSO meridional circulation dynamics on long term variations in precipitation. We also introduced new constraints on the significance of variations in the eNd analysed on foraminifera from the Gulf of Bengal by estimating the proportion of these changes linked to variations in Himalayan erosion as opposed to those linked to the dynamics of deep ocean water masses.
The Role of the Southern Ocean in carbon exchanges since the last Glaciation: a geochemical and micropaleontological approach
Director: Giuseppe SIANI (GEOPS).
Funding: Alloc. MESR
Thesis defended on December 12th, 2016
SUMMARY
The last 22,000 years are marked by rapid climatic events that are not synchronous between the northern and southern hemispheres. A see-saw mechanism in polar temperatures, amplified by the capacity of the deep ocean to store and release a portion of atmospheric CO2 depending on the intensity of oceanic circulation and upwelling along the Southern divergence, has been forwarded as an explanation for these events. The aim of this thesis was to define the role of the Southern Ocean during these rapid climatic variations using three marine cores from the margins of Chile which are influenced by oceanic fronts and winds from the west. The reconstruction of sea surface temperatures (SST) allowed us to trace the evolution of the SST latitudinal gradient over the past 22,000 years, highlighting southward migrations of the Subtropical front, particularly during the deglaciation, marked by changes in faunal changes in benthic and planktonic foraminifera which suggest an increased supply of surface nutrients and accompanied by [O2] enrichment of the bottom water. These events may perhaps be linked to a strengthening of upwelling at the southern divergence which would have led to greater ventilation of Antarctic intermediate waters. These hydrological variations occur during the rise in atmospheric CO2 recorded in Antarctic ice cores during the deglaciation, indicating a close link between the upwellings, the intensity of ventilation of intermediate waters and the transfer of CO2 from the deep ocean to the atmosphere.
Erosional history of the Himalaya during the last climatic cycles : sedimentological, mineralogical and geochemical investigation of sediments fromt he proximal part of the Bengal deep-sea fan
Director: Christophe COLIN (GEOPS)
Funding: CSC (China Scholarship Council)
Thesis defended on December 8th, 2016
SUMMARY
The Himalayan region displays some of the highest rates of physical and geochemical weathering in the world, thus making it a key region for studying the relationships that exist between climate and erosion. Over the course of the Quaternary, variations in precipitation linked to monsoon intensity constitute the principal factor controlling chemical alteration and physical erosion in the Himalayas and neighbouring regions. The northern part of the Bay of Bengal (proximal part), which is principally fed by the Ganges and Brahmaputra Rivers, provides a direct record of the variability of erosion intensity in the Himalayas. This erosion is itself linked to paleoclimatic and paleoenvironmental changes affecting South West Asia. Very high resolution studies of the mineralogy of the clay fraction and the granularity of the sediments, as well as measurements of the Nd and Sr isotopic compositions, coupled with major element analyses, were carried out on several cores taken during the MONOPOL mission. We demonstrated that significant erosion zones in the Ganges-Brahmaputra catchment area change greatly as a function of modifications in the intensity of monsoon precipitation over the course of the Holocene. We also revealed the important roles played by sea level and monsoon rains in the variability of sedimentary sources and in the activity of turbiditic currents situated to the east of the underwater fan in the Bay of Bengal.
Reconstruction of the hydrology of the NE Atlantic based on Nd isotope analysis and the impact of environmental changes on the growth of deep coral reefs
Director: Christophe COLIN (GEOPS)
Funding: MESR
Thesis defended on June 3rd, 2016
SUMMARY
The North-East Atlantic and the Mediterranean Sea present highly contrasting neodymium (εNd) isotopic compositions at the scale of their respective basins, reflecting the heterogeneous distribution of geological formations that contribute to sources of dissolved Nd in the ocean. In this thesis Nd isotopes from deep water corals and foraminifera have been used to reconstruct the evolution of intermediate water mass dynamics since the Last Glacial period in the North-Eastern Atlantic and in the Western Mediterranean. The aim is to provide constraints regarding the role of intermediate water masses, particularly during periods of slowing oceanic circulation during the last Glacial or during the period when sapropel S1 was deposited; this latter period is characterized by a very significant change in Mediterranean circulation. The εNd values calculated for sea water in the North-East Atlantic indicate that the isotopic signature of the sub-polar gyre predominates as far as intermediate depths. Consequently, the significant variations in εNd measured in deep water corals indicate strong hydrological changes in the period since the Last Glacial, changes that are linked gyre dynamics and the intensity of oceanic convection. In the Mediterranean, the disappearance of the east-west gradient in εNd values during the deposition of sapropel S1 reveals an inversion of circulation within the western basin.
Wu QIONG: Study of the Sr and Nd isotopic compositions of sediments in the South China Sea: reconstruction of the sources and current sedimentary dynamics of the NE margin of the South China Sea. Funding: Tongji University. Stay in France in 2016. Collaboration between C. Colin and Z. Liu.
Claudia ARACENA: Post-glacial evolution of paleoproductivity off the coast of Central Patagonia. Funding: CONICYT within the framework of ECOSUD. Two-month stay in France from March to May 2016. Collaboration between G. Siani and R. De Pol-Holz.
Lucile BONNEAU: Study of the Nd isotopic composition of deep water corals in the North Atlantic. Funding for 12 months post-doc salary in 2015: ANR HAMOC. Collaboration between GEOPS (C. Colin) and the LSCE.
Lucie BAZIN: Developing and testing integrated, multi-archive chronologies to improve our understanding of past, rapid climate changes and bifurcations. Labex-IPSL Funding for 12 month post-doc salary in 2015. Collaboration between GEOPS (G. Siani) and the LSCE (A. Landais).