School of Earth and Environment

Dr Martin Schobben

DFG Research Fellow

Email address: M.Schobben@leeds.ac.uk

Affiliation: Earth Surface Science Institute

Biography

After my MSc at the University Utrecht (Netherlands), I continued with a PhD in Earth sciences in Berlin (Germany). I obtained my PhD degree from the Freie Universität Berlin in January, 2015. However, the actual work was conducted at the Museum für Naturkunde Berlin and involved an intensive collaboration with the University of Münster, Erlangen-Nürnberg and Copenhagen. My PhD research involved the study of the end-Permian mass extinction by means of isotope geochemical analyses on sedimentary rock and fossil material collected in Iran, and had the title: Geochemical proxy records identifying climatic and environmental changes across the Permian-Triassic boundary of key sections in NW Iran.

Research Interests

My research interests broadly focuses on the interaction of organisms with their environment, the large biogeochemical cycles and climate, during pivotal periods in the Earths’ history. As a tool I employ geochemical signatures locked in marine sedimentary rocks, such as carbon, oxygen and sulfur isotope composition, as well as in individual fossils, such as the oxygen isotope composition in brachiopod shell calcite and conodont apatite. These geochemical proxies can record physical and chemical parameters of ancient time intervals and hold the premise of understanding the evolution of the ocean chemistry as well as climate through time. By employing multiple proxies and performing isotope analysis on multiple components of the rock, I try to isolate primary from diagenetic signals, the latter which can be the result of burial, lithification and successive heating. Diagenetic overprinting can obscure the use of these geochemical tools to reconstruct the ancient environment, if left unaccounted for. By pealing out the best retained environmental signals and by performing numerical simulations (box-models), I ultimately hope to reconstruct the environmental backdrop of turbulent time-intervals, when life on Earth went through a bottleneck (i.e., mass extinctions), in a more quantitative manner.

Project details

Project title

A PHase-Specific geochemical study of marine PRoductivity and nutrient cycling during the end-Permian mass extinction (PHoSPhoR)

Funding

Deutsche Forschungsgemeinschaft (DFG)-Research Fellowship (SCHO 1689/1-1)

Project outline

During my current project, funded by a Deutsche Forschungsgemeinschaft (DFG) fellowship, I want to study changes in nutrient availability and marine productivity that, perhaps, contributed to the end-Permian mass extinction. This event represents the most dramatic faunal turnover during the last 500 million years, followed by a prolonged 2-5 million-year period of marine ecosystem instability. The cause(s) of this event are still much debated. One open question concerns whether the event is associated with an ocean (almost) barren of life (a primary productivity collapse), or conversely, that the event represents a biodiversity crash amongst multi-cellular eukaryotes, but with otherwise generally high-marine productivity levels. Central to this study will be a detailed evaluation of ocean redox conditions, using the most recently developed Fe speciation technique , in addition to utilising recent advances in our understanding of the differential behaviour of trace metals under different redox conditions. This will yield sensitive and robust proxy records for identifying a range of redox regimes (oxic, dysoxic, anoxic-sulphidic, or anoxic-ferruginous). These analyses will set the scene for the next geochemical phase, which will involve the highly novel application of phosphorus speciation techniques and barium concentrations to extract information about ancient nutrient fluxes (and recycling) and marine productivity.

Publications

Schobben, M., Ullmann, C. V., Leda, L., Korn, D., Struck, U., Reimold, W. U., Ghaderi, A., Algeo, T. J., Korte, C. (2016), Discerning primary versus diagenetic signals in carbonate carbon and oxygen stable isotope records: An example from the Permian-Triassic boundary of Iran. Chemical Geology 422, 94-107.

Schobben, M., Stebbins, A., Ghaderi, A., Strauss, H., Korn, D., Korte, C., (2016), Eutrophication, microbial-sulfate reduction and mass extinctions, Comparative and Integrative Biology 9(1), 1-9.

Korn, D., Ghaderi, A., Leda, L., Schobben, M. and Ashouri, A.R. (2015), The ammonoids from the Late Permian Paratirolites Limestone of Julfa (East Azerbaijan, Iran). Journal of Systematic Palaeontology 2019, 1-50.

Schobben, M., Stebbins, A., Ghaderi, A., Strauss, H., Korn, D., Korte, C., (2015), Flourishing ocean drives the end-Permian marine mass extinction. Proc Natl. Acad. Sci. U.S.A. 112, 10298–10303.

Schobben, M., Joachimski, M. M., Korn, D., Leda, L., Korte, C. (2014), Palaeotethys seawater temperature rise and an intensified hydrological cycle following the end-Permian mass extinction, Gondwana Research 26, 675-683.

Ghaderi, A., Leda, L., Schobben, M., Korn, D., Ashouri, A. R., (2014), High-resolution stratigraphy of the Changhsingian (Late Permian) successions of NW Iran and the Transcaucasus based on lithological features, conodonts and ammonoids, Fossil Record 17, 41–57.

Hillebrandt, A.v., Krystyn, L., Kürschner, W. M., Bonis, N. R., Ruhl, M., Richoz, S., Schobben, M., Urlichs, M., Bown, P. R., Kment, K., McRoberts, C. A., Simms, M., Tomãsových, A., (2013), The Global Stratotype Sections and Point (GSSP) for the base of the Jurassic system at Kuhjoch (Karwendel Mountains, Northern Calcareous Alps, Tyrol, Austria), Episodes 36(3), 162-198.