The Interplay Between the Eruption and Weathering of Large Igneous Provinces and the Deep-Time Carbon Cycle

Although many sources of atmospheric CO2 have been estimated, the major sinks are poorly understood in a deep-time context. Here we combine plate reconstructions, the eruption ages and outlines of Large Igneous Provinces (LIPs), and the atmospheric CO2 proxy record to investigate how their eruptions and weathering within the equatorial humid zone impacted global atmospheric CO2 since 400 Ma. Wavelet analysis reveals significant correlations between the eruption of the Emeishan LIP (259 Ma), the Siberian Traps (251 Ma), the Central Atlantic Magmatic Province (201 Ma), the second pulse of the North Atlantic Igneous Province (55 Ma), the High Arctic LIP (130 Ma), and the Deccan Traps (65 Ma) and perturbations in atmospheric CO2. Our analysis also reveals a clear relationship between the weathering of the Central Atlantic Magmatic Province (similar to 200-100 Ma), the Deccan Traps (50-35 Ma), and the Afar Arabian LIP (30-0 Ma) and a significant atmospheric CO2 drawdown. Our results illustrate the significant role of subaerial LIP emplacement and weathering in modulating atmospheric CO2 and Earth's surface environments. Plain Language Summary Carbon dioxide in the atmosphere plays a significant role in regulating Earth's climate. There are many processes, which over geologic timescales add to or sequester CO2 from the atmosphere, and in turn alter Earth's climate. Here we investigate processes involved in the eruption and weathering of Large Igneous Provinces (LIPs), massive nonexplosive volcanic eruption of basaltic lava and rock. During eruptions, LIPs contribute significant amounts of CO2 to the atmosphere in very short periods of geologic time, and subsequently, when basalt is exposed to physical and chemical weathering, the process will draw CO2 from the atmosphere. We consider both eruptions, and the subsequent latitudinal positions of the LIPs in the context of their weathering, which is most severe at low latitudes due to high tropical precipitation rates. We find that periods of elevated atmospheric CO2 were related to the eruption of the Emeishan LIP and Siberian Traps (260-240 Ma), the Central Atlantic Magmatic Province (210-190 Ma), and the North Atlantic Igneous Province, High Arctic LIP, and the Deccan Traps (90-60 Ma) and those of lowered CO2 to be related to weathering of the Central Atlantic Magmatic Province (similar to 200-100 Ma), the Deccan Traps (as it drifted through low latitude regions similar to 50-35Ma), and the Afar Arabian LIP (30-0 Ma). Our analysis reveals the significant role LIPs have played in modulating Earth's climate.