Stellenangebot: Doctoral researcher (f_m_x) - project GHOST bei GFZ Helmholtz-Zentrum für Geoforschung

The GFZ Helmholtz Centre for Geosciences is one of the world's leading institutions in the field of geosciences. As part of the Helmholtz Association, Germany's largest research organisation, we address global challenges such as natural hazards, climate change and the sustainable use of resources. In doing so, we combine cutting-edge research with social relevance. Our international staff - around 1,200 employees and approx. 500 guests - work in a multidisciplinary way and with a unique infrastructure to research the dynamic processes of the Earth system. Our vision: “Taking the pulse of the Earth to safeguard a habitable planet.”

For section 4.6 Geomorphology (department “Geosystems”), we are looking for a:

Doctoral researcher (f_m_x) - project GHOST

Reference Number 11496

GHOST (DFG-funded project): Loss of organic carbon in the eastern Mediterranean: investigating the elusive “ghost sapropels” and “red intervals”

The GHOST project will focus on elucidating the climatic and oceanic drivers leading to the formation of the enigmatic "ghost sapropels" in Mediterranean sediments during the past 3 million years. Sapropels are organic-rich sediments preserved over geological time, including in the deepest parts of the Mediterranean Sea. Because their formation process involves complex land-ocean linkages and large-scale ocean deoxygenation, they are often considered natural laboratories for understanding the timing and drivers of such processes.

In this project, we will focus on sapropels where the organic carbon is not preserved, called "ghost sapropels". They occur synchronously in the Mediterranean basin and seem paced by Milankovitch cycles, but the driving mechanism remains elusive. This project will exploit national and international collaborations to use multiple isotopic tools and the extraction of specific sedimentary fractions at four ODP sites, as well as numerical models. Through this data-model approach, we will test a set of working hypotheses that will enable us to understand the processes leading to the lack or loss of carbon in ghost sapropels. Ultimately, we aim to assess how the lack or loss of organic carbon in ghost sapropels affected the carbon cycle.

As part of this international project, your role will be to perform isotopic measurements (radiogenic Nd and Sr isotopes, stable O, C, and potentially Li isotopes) in two clean laboratories at the GFZ (Potsdam, Germany) and GEOMAR(Kiel, Germany). You will sample four ODP legacy cores stored at the national repository in Bremen and will extract specific sedimentary fractions based on the chemistry and grain-size distribution of bulk sediments for the isotopic analyses. In close collaboration with colleagues at the Laboratoire des Sciences du Climat et de l'Environnement (Paris-Saclay, France), you will perform numerical experiments with the FESDIA diagenesis model to help determine the role of different parameters on the fate of organic carbon in these sediments. The dataset you generate will provide new insights into the long-term changes in hydroclimates in North Africa as well as into Mediterranean Sea paleocirculation.

You will be based in the Geomorphology section at the GFZ, a vibrant and diverse group of researchers. Here, you will be exposed to a wide range of scientific methods and projects that foster curiosity and motivation and provide a collaborative and supportive scientific culture. We commit to supporting the development of early-career scientists through attentive and agile supervision.

Your responsibilities:

• Perform sedimentological and geochemical analyses, including chemical extractions, grain-size measurements, and isotope ratio analyses. Purification and measurement of isotope ratios of specific elements (Sr, Nd, Li) will be realised in a class 1,000 clean laboratory using ion-exchange column chromatography and several mass spectrometers. Laboratory work will be performed at GFZ with a planned research stay at GEOMAR (Kiel, Germany)
• Design and run simulations in the FESDIA model (research stay at the LSCE, France)
• Assemble published data for the Mediterranean Sea as databases, acquire and manage new data to be safely stored in our internal databases and published as data publications
• Liaise with partners in the project to mobilise their expertise and exchange information
• Publish high-quality scientific publications and present at international conferences, under the guidance of the supervisor and project partners

About You:

Essential Qualifications:

• MSc degree in Geoscience, with a speciality in Geochemistry, Sedimentology, Palaeoceanography and/or Palaeoclimates
• Good knowledge of sedimentology
• Advanced level in English, both spoken and written
• Willingness and capacity to travel in Europe and spend time at our partner institutes, good interpersonal and communication skills

Desirable Qualifications:

• Experience with clean-lab techniques, column chromatography and/or MC-ICP-MS measurements
• Experience with sampling and handling soft sediments
• Knowledge of African palaeoclimates, Mediterranean oceanic and sedimentary environments and/or processes occurring during early diagenesis
• Structured working skills and ability to receive and provide feedback

Start date: 1st January 2027
Fixed-term: 3 Jahre
Salary: Die Stelle ist nach TVöD Bund mit der Entgeltgruppe 13 bewertet. Die Eingruppierung erfolgt nach den tariflichen Bestimmungen und den entsprechenden persönlichen Voraussetzungen.
Working hours: Teilzeit 75% (derzeit 29,25 h/Woche)
Place of work: Potsdam

What we offer:

• Ambitious and varied tasks in a dynamic and international research environment
• State-of-the-art equipment
• Public service benefits
• Extensive training opportunities
• Professional career advice offered by our in-house Career-Centre
• Flexible working hours and conditions
• Support with finding a good work-life balance offered by benefit@work
• Institute day-care centre on site
• Working at the Albert Einstein Science Park on the Telegrafenberg in Potsdam
• Workplace within walking distance of Potsdam main train station, or just a short ride on the shuttle bus

Have we piqued your interest?

If so, we look forward to receiving your application by 30th September 2026. Please use our online application form only.

Required documents: CV, letter of motivation, grades/certificates

The GFZ actively promote diversity and equal opportunities. We explicitly welcome applications from all qualified individuals, regardless of ethnic and social origin, nationality, gender, sexual orientation and identity, religion/belief, age, and physical or neurodiverse abilities.

“Diversity in perspectives” is one of GFZ's core values. As an integral part of supporting diversity at our centre, we actively promote women in science and in leadership positions. To know more about our Diversity policies, contact the diversity team. If you need more information about our gender equality policies, please do not hesitate to contact our Equal Opportunities Officer and check our Equal Opportunities Plan & Cascade Model.

We look forward to applications from people who enjoy working in diverse teams, where everyone feels respected and valued and can fully develop their own talents. Applicants with severe disabilities and equalised persons will receive preferential consideration if equally qualified.

Data protection information for applicants

In case of any further queries regarding the field of activity, please contact Dr. Cécile L. Blanchet via email. If you have any general questions about the application process, please contact our recruiting team at our phone number +49 (0) 331-6264-28787.