dr. JM Koornneef

Janne Koornneef is an isotope geochemist studying the composition of the Earth’s mantle and the volcanic rocks derived from it. She aims to understand the processes that control the compositional variability of lavas and has a specific interest in melt- and fluid related processes within the mantle. She uses multiple isotope systems (Nd, Sr, Hf, Pb, C, B, S, U-series) in combination with major- and trace element chemistry of mantle and volcanic rocks to look at: (1) mantle plume chemical geodynamics; (2) mantle melting rates and melt transport times (3) the influence of source heterogeneity on the melting process and lava compositions; (4) Recycling fluxes in subduction zones (5) mantle metasomatism and diamond formation processes in subcratonic mantle.

Projects

At the core of her career lies the development of analytical techniques capable of analysing the radiogenic isotope compositions of extremely small samples. As postdoc she improved and validated 10¹³ Ω amplifier technology for mass spectrometry in collaboration with the instrument manufacturer, Thermo Scientific. This work led to incorporation of the technology in a broad range of commercial instruments. The ten-fold improved analytical precision on Sr-Nd-Pb isotope ratios provided a technical breakthrough. She applied the techniques to generate new insights based on magmatic rocks and diamonds and to dust provenance in ice cores for paleoclimate reconstruction.

Until becoming tenured in 2016, she co-authored multiple grants and supervised four PhDs and three postdocs applying methods to date inclusions in diamonds but also in projects across disciplinary boundaries in archaeology, forensics and cultural heritage.

As assistant professor she was awarded an ERC-Starting Grant (2018-2023; 1.75M€). Within the “ReVolusions” project she led a team of two PhDs and a postdoc. The team determined isotope compositions of olivine-hosted melt inclusions to study element recycling subduction zones. Melt inclusions are tiny droplets (~100 μm) of magma trapped in minerals that grow at depth below volcanoes. These droplets more accurately record the mantle’s composition compared to bulk lavas. 

As associate professor she now steers a team to study the compositions of the deep mantle through analysing melt inclusions from Hawaii, Reunion and Iceland (NWO-OC-M1). In a parallel project with Prof. van Westrenen they aim to better determine the mantle’s CO₂ composition and volcanic outgassing using high-pressure experimental techniques on melt inclusions (NWO-OC-M1). These projects place more quantitative constraints on Earth’s interior evolution and the deep carbon cycle.

As head of the “The Netherlands Isotope GEochemistry Laboratory-NIGEL” housed in the new VU Research Building she manages the expanded and modernised mass spectrometry lab. The NIGEL facility, financed by a NWO-Large Infrastructure includes eight state-of-the-art analytical instruments installed in 2025 and a custom-built clean laboratory. Two post-docs will be appointed between 2026-2029. The NIGEL infrastructure serves national researchers from 14 Dutch geology, archaeology and cultural heritage institutes and provides transnational access for collaborative projects through the Europlanet and E-RIHS infrastructure programs.

Visit her personal website at: jannekoornneef.nl

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