Global rift analysis of tectonic and magmatic characteristics: towards constraining rift-related CO₂ degassing over geological timescales

The release of carbon at plate boundaries strongly influences Earth’s long-term climate over geological timescales. Continental rifts, in particular, are thought to play a major role in CO₂ degassing by activating carbon reservoirs in the deep lithosphere, with magmatic rifting enabling efficient CO₂ transport via carbonate-rich melts, especially during the early stages of rift development (Foley and Fischer, 2017). Substantial uncertainties in global degassing rates remain, as the incomplete geological record limits precise constraints on the timing, magnitude, and controlling factors of rift-related CO₂ release.To reduce these uncertainties and enable time-dependent estimates of CO₂ degassing at continental rifts worldwide, we quantify first-order rift characteristics that are expected to control CO₂ degassing. Our analysis employs automated geoinformation workflows and builds on a newly compiled global database of more than 1500 Phanerozoic rifting events, providing a systematic framework for quantifying rift properties.Here, we focus on three key characteristics: (I) proximity to cratonic lithosphere as an indicator of access to deep carbon reservoirs, (II) crustal thickness as a proxy for rift maturity and tectonic evolution, and (III) the distinction between magmatic and non-magmatic rifting styles, as provided by the global rift database, reflecting differences in the role of magma and volatile transport pathways. Crustal thickness and craton proximity are evaluated using multiple global crustal models and alternative craton boundary interpretations. These characteristics are linked to published present-day CO₂ flux measurements from active rift systems to derive relationships between rift properties and degassing rates. In the future, we aim to use these relationships in conjunction with plate tectonic reconstructions to derive global, time-dependent CO₂ degassing estimates throughout Phanerozoic times. References: Foley, S. F., & Fischer, T. P. (2017). An essential role for continental rifts and lithosphere in the deep carbon cycle. Nature Geoscience, 1. https://doi.org/10.1038/s41561-017-0002-7