List of Projects Dr. Sebastian Viehmann

Abstract: Antimony (Sb) is a toxic element that primarily occurs in sulfur-rich ore bodies, and its uptake into the human body over extended periods can lead to cancer, disturbances in the optical nerves (e.g., uveitis, retinal hemorrhages), and heart disease. In recent years, Sb isotope ratios have been used as a geochemical environmental tracer due to Sb's high redox sensitivity, to trace contamination pathways from spoil heaps into soils and waters, and to better control human health impacts. Additionally, it has recently been shown that Sb isotopes in Sb-rich minerals can serve as an exploration tool, providing clues about the formation of undiscovered Au, Ag, and Cu-Sb deposits underground.
In the proposed project, Sb isotope ratios will be used to(I) determine the environmental impact of Sb (and other toxic elements in sulfides such as As) on soils, waters, and drinking water near mines, thereby assessing the direct impact on humans. (II) Furthermore, Ag- and Au-rich mines such as the Rammelsberg, St. Lorenz, or Agezucht mines in the Harz region will be used as case studies to apply Sb isotopy as an exploration tool in Sb minerals to potentially locate additional undiscovered ore bodies underground.

The project is a granting project ("Vergabeprojekt)" by the Federal Institute for Geosciences and Natural Resources (BGR) under project number P-204-4500139869.

Abstract: This project aims to reconstruct marine environments and the geodynamical evolution of continental landmasses in the time frame between 2.9 and 3.5 billion years ago. The results provide fundamental insights into how landmasses and marine environments evolved through the Archean and improve our current understanding from the interplay of weathering and erosion processes of emerged landmasses with marine environments on Early Earth.
In particular, the results provide unique information on the evolution of local and global Archean seawater chemistry, the atmos- and hydrosphere systems, as well as the sources of elements affecting Archean seawater. Additionally, Hf-Nd isotope compositions determine the impact of elemental fluxes from emerged continents into Archean marine environments. For the first time, this project traces the Hf-Nd isotope record of oceans from 2.7 billion years back until ~3.5 billion years ago and establishes Hf-Nd isotopes in marine chemical sediments as novel geochemical proxy for weathering and erosion processes on Precambrian continents. In particular, the results pinpoint the time in Earth's history when landmasses were - for the first time - emerged and significantly affected seawater chemistry via chemical weathering.