Mechanisms of Vanadium Enrichments in shale-hosted deposits: insights from a novel redox tracer (Project MoVE)

• Applicant: Ashley Martin, Ph.D.
• Subject Area: Mineralogy, Petrology and Geochemistry ; Palaeontology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 521737749

There is growing demand for redox-sensitive metals such as vanadium (V) in the energy transition, as large quantities of these critical metals are required to produce rechargeable redox-flow batteries for storing renewable energy. These new high-tech applications combined with conventional use of V in steel alloys requires new V sources, such as shale-hosted deposits. Such highly V enriched deposits are recognised in North America, China and Europe but their formation is enigmatic. All shale-hosted V deposits are organic-rich and are assumed to form in restricted basins under euxinic (anoxic and sulfidic) conditions. There are long-standing debates regarding their formation mechanisms: 1) the relative importance of seawater versus hydrothermal sources for these metals; and 2) whether the deposits formed under a euxinic water column or in the sub-oxic zone with a fluctuating oxic-anoxic interface. Due to the organic-rich nature of these deposits, micro-organisms may promote metal enrichment, but this is less explored. Project MoVE will innovatively combine new developments in isotope geochemistry and inter-disciplinary collaborations with microbiologists to resolve these debates. A central focus of this project is the application of the novel V isotope redox proxy to exemplary shale-hosted V deposits in the Yangtze Platform, southern China, and the Selwyn Basin, north-western Canada. Vanadium isotopes are a powerful redox tracer because there is a distinct isotopic signature associated with V precipitation under oxic, anoxic and euxinic water columns. In addition, there is a unique V isotope signature for V precipitation in hydrothermally overprinted sediments. This new V isotope dataset will provide quantitative evidence to resolve the debate of hydrothermal vs seawater as a source of V. If the data are not consistent with a hydrothermal origin of V, the V isotope data will reveal whether the water column was persistently oxic, anoxic and euxinic, or oscillated between these redox states. New research avenues will be explored to better understand the role of organic matter and micro-organisms in generating metal enrichments: 1) combining V isotope and nitrogen isotope measurements to constrain biological productivity during the genesis of shale-hosted V deposits and 2) generating the first V isotope dataset for experimental microbial V reduction. In summary, Project MoVE will employ a cross-disciplinary approach combining the novel V isotope redox proxy with traditional stable isotopes and microbial V reduction experiments. This project will refine models for the genesis of global V shale-hosted deposits and pioneer collaborations between geologists, geochemists and micro-biologists.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2238: Dynamics of Ore-Metals Enrichment - DOME
• International Connection: United Kingdom