1,2,1,2,4,5,5,4,6,6,6,9,- 1University of Bern, Institute of Geological Sciences, Switzerland (aliisalaakkonen@hotmail.com)
- 2Oeschger Centre for Climate Change Research, University of Bern
- 3Eawag, Federal Institute of Aquatic Research and Technology, Department W+T, Switzerland
- 4Institute for Geography and Geology, University of Greifswald, Germany
- 5Institute of Earth Surface Dynamics, Faculty of Geoscience and Environment, University of Lausanne, Lausanne, Switzerland
- 6State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, China
- 7School of Geography, Politics and Sociology, Newcastle University, UK
- 8Department of Natural Sciences, Manchester Metropolitan University, UK
- 9Department of Geosciences, University of Fribourg, Fribourg, Switzerland
The Tibetan Plateau, with an average elevation of 4000 m above sea level, is the highest plateau on Earth. It is the third largest store of ice after the Arctic and Antarctic and is often referred to as the ‘Third Pole’. It is an area sensitive to climate shifts and is expected to go through significant warming in the future. Nam Co in central Tibet is located in the modern monsoon regime and was recently drilled as part of the ICDP NamCore drilling project, which aims to reconstruct the Quaternary climate history of the region.
Lake sediments act as paleoenvironmental archives; with minerals forming in the water column reflecting the prevailing environmental conditions, which then become part of the sediment package after deposition. However, post-depositional processes, such as early diagenesis, can cause alteration in mineralogy, structure and/or chemistry of deposited sediments. This can happen through sediment compaction, fluid circulation and physico-chemical changes, often mediated by microbial activity in situ.
We report results about authigenic minerals and mineral evolution in Nam Co. The aim is to target different diagenetic formation pathways of pyrite by combining detailed structural and compositional data, such as high-resolution X-ray computed micro-tomography (μCT), X-ray fluorescence scanning, and sulphur isotope analyses. We hypothesise the formation of pyrite in Nam Co happens because of diagenetic processes and pathways driven by changes in hydrology and limnology, tectonically induced fluid flow, and microbial activity. The overarching aim is to disentangle these different formation processes, and to assess whether we can use the sulphur isotope composition of pyrite to discriminate between environmental and tectonic controls.
How to cite: Laakkonen, A., Thomas, C., Moser Roeggla, P., Adolph, M.-L., Ceriotti, G., Berg, J., Kipfer, R., Haberzettl, T., Ju, J., Henderson, A., Clarke, L., Zhu, L., Wang, J., Foubert, A., and Vogel, H.: Diagenetic formation pathways of pyrite in Nam Co, a high-altitude Tibetan lake , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9076, https://doi.org/10.5194/egusphere-egu26-9076, 2026.
