Instant weathering response to carbon-cycle perturbations during the end-Triassic extinction

Constraints on the continental weathering feedback on carbon-cycle perturbations on northern Pangea during the end Triassic extinction (ETE) are sparse. Here, we use hyperspectral core imaging (HSI) applied to conglomeratic beds offshore central Norway which shows that enhanced degassing of basalt flows from the Central Atlantic magmatic province (CAMP) was concurrent with intense continental transformation during the ETE. We use well-constrained mercury pulses emitted in gaseous form during volcanism, and subsequently deposited in near-coastal sediments, to identify the ETE. Parallel to mercury pulses, HSI derived smectite was immediately replaced by kaolinite at the extinction level corroborating increased radiogenic run-off from the hinterland as inferred from osmium isotopes. Our new results suggest that, parallel with CAMP activity and with atmospheric carbon dioxide (pCO₂) up to four times the pre-extinction level, continental weathering instantaneously intensified, providing novel empirical knowledge that can be integrated in carbon-cycle models to underpin future warming assessments.