2:45 PM - 3:00 PM
[SCG57-05] Massive volcanism and its impact on the global environment through Earth History
★Invited Papers
Keywords:Massive eruption, Environment change, Toba Eruption
Massive volcanic eruption and its impact on the global environment through Earth History
Large volcanic eruptions have a variety of effects on the Earth's climate and ocean. For example, the 1991 eruption of Pinatubo lowered tropospheric temperatures by up to 0.7°C for two years. Some studies suggested that large volcanic eruptions act as an important forcing for multidecadal climate oscillations. Such short-term impacts of volcanic eruptions on the atmosphere and ocean system are becoming better understood in recent years. However, the impact of more massive volcanic eruptions on the atmosphere and ocean during geologic past, when instrumental observations were not available, has yet to be studied. Recent studies using marine sediments have been actively conducted to discuss past large-scale volcanic activities and their effects on climate and oceanic environments. We will focus on several events in the Earth's history and introduce their links.
1. Toba Volcano. Toba volcano in Indonesia erupted about 74 ka, one of the largest eruption during Quaternary. Younger Toba Tephra (YTT) is widely distributed in the Indian Ocean. During a drilling expedition in the Bay of Bengal by D/V Chikyu, a 5 cm-thick volcanic ash layer was recovered (Ota et al., 2019). High-resolution geochemical analyses did not show any significant decrease in sea surface temperature immediately after the eruption. The timing of the Toba volcano was determined precisely based on the sulfur isotopic composition of polar ice cores (Crick et al. 2021), and it was found that the volcano erupted after the onset of the subglacial period GS-20. Thus the eruption itself did not trigger global cooling.
2. Deccan Traps. The Deccan Traps in India, which erupted at the end of the Cretaceous, may have caused warming in the Maastrichtian (Barnet et al., 2017). This is an excellent example to see the impact of volcanic activity causing warmth in the longer timescale. Some powerful tools to constrain the timing of the onset of the volcanic event include the zircon U-Pb dating of lava (Schoene et al., 2019), and Os isotopic record (187Os/188Os) of marine sediments (Robinson et al., 2009). Integrating these geochemical datasets should constrain a more precise timing, order or chronological relationship of flood basalt emplacement and Maastrichtian warming.
3. Ontong Java Plateau. Several large oceanic plaetaus, including the Ontong Java Plateau, were formed in the middle of Cretaceous. The history of eruption and emplacement of these plateaus can be constrained not only by the study of the igneous rocks themselves, but also by the sediments of the surrounding seafloor. We introduce here some studies that demonstrated the possibility of the latter approach. The timing of a shift of Os and Pb isotope ratios of sediment to the values of the igneous rocks of the large igneous provinces can be used to constrain their eruption and formation ages. These data also suggested that the onset timing of the volcanic eruptions forming some large igneous provinces apparently coincided with the timing of oceanic anoxic events, turnover of marine organisms, and shifts in carbon isotope ratios (e.g., Matsumoto et al., 2022), allowing us to examine the possibility that changes in ocean circulation, biological extinctions, and the carbon cycle perturbation may have been caused by volcanic activities in association with the formation of large igneous provinces.
Climate may also have been drastically changed by the release of greenhouse gases due to contact metamorphism as a result of magma intrusions into organic carbon-rich sediments. In our presentation, we would like to discuss the potential impacts of volcanic and igneous activities on the climate and oceans in an integrated manner.
Barnet, J.S.K., Littler, K., et al. (2017) Geology, 46, 147-150.
Crick, L., Burke, A., et al. (2021) Climate Past, 17, 2119-2137.
Matsumoto, H., Coccioni, R., et al. (2022) Nature Comm., 13, no. 239.
Ota, Y., Kawahata, H., et al. (2019) Geochem., Geophys., Geosys., 20, 148-165.
Schoene, B., Eddy, M.P., et al. (2019) Science, 363, 862-866.
Large volcanic eruptions have a variety of effects on the Earth's climate and ocean. For example, the 1991 eruption of Pinatubo lowered tropospheric temperatures by up to 0.7°C for two years. Some studies suggested that large volcanic eruptions act as an important forcing for multidecadal climate oscillations. Such short-term impacts of volcanic eruptions on the atmosphere and ocean system are becoming better understood in recent years. However, the impact of more massive volcanic eruptions on the atmosphere and ocean during geologic past, when instrumental observations were not available, has yet to be studied. Recent studies using marine sediments have been actively conducted to discuss past large-scale volcanic activities and their effects on climate and oceanic environments. We will focus on several events in the Earth's history and introduce their links.
1. Toba Volcano. Toba volcano in Indonesia erupted about 74 ka, one of the largest eruption during Quaternary. Younger Toba Tephra (YTT) is widely distributed in the Indian Ocean. During a drilling expedition in the Bay of Bengal by D/V Chikyu, a 5 cm-thick volcanic ash layer was recovered (Ota et al., 2019). High-resolution geochemical analyses did not show any significant decrease in sea surface temperature immediately after the eruption. The timing of the Toba volcano was determined precisely based on the sulfur isotopic composition of polar ice cores (Crick et al. 2021), and it was found that the volcano erupted after the onset of the subglacial period GS-20. Thus the eruption itself did not trigger global cooling.
2. Deccan Traps. The Deccan Traps in India, which erupted at the end of the Cretaceous, may have caused warming in the Maastrichtian (Barnet et al., 2017). This is an excellent example to see the impact of volcanic activity causing warmth in the longer timescale. Some powerful tools to constrain the timing of the onset of the volcanic event include the zircon U-Pb dating of lava (Schoene et al., 2019), and Os isotopic record (187Os/188Os) of marine sediments (Robinson et al., 2009). Integrating these geochemical datasets should constrain a more precise timing, order or chronological relationship of flood basalt emplacement and Maastrichtian warming.
3. Ontong Java Plateau. Several large oceanic plaetaus, including the Ontong Java Plateau, were formed in the middle of Cretaceous. The history of eruption and emplacement of these plateaus can be constrained not only by the study of the igneous rocks themselves, but also by the sediments of the surrounding seafloor. We introduce here some studies that demonstrated the possibility of the latter approach. The timing of a shift of Os and Pb isotope ratios of sediment to the values of the igneous rocks of the large igneous provinces can be used to constrain their eruption and formation ages. These data also suggested that the onset timing of the volcanic eruptions forming some large igneous provinces apparently coincided with the timing of oceanic anoxic events, turnover of marine organisms, and shifts in carbon isotope ratios (e.g., Matsumoto et al., 2022), allowing us to examine the possibility that changes in ocean circulation, biological extinctions, and the carbon cycle perturbation may have been caused by volcanic activities in association with the formation of large igneous provinces.
Climate may also have been drastically changed by the release of greenhouse gases due to contact metamorphism as a result of magma intrusions into organic carbon-rich sediments. In our presentation, we would like to discuss the potential impacts of volcanic and igneous activities on the climate and oceans in an integrated manner.
Barnet, J.S.K., Littler, K., et al. (2017) Geology, 46, 147-150.
Crick, L., Burke, A., et al. (2021) Climate Past, 17, 2119-2137.
Matsumoto, H., Coccioni, R., et al. (2022) Nature Comm., 13, no. 239.
Ota, Y., Kawahata, H., et al. (2019) Geochem., Geophys., Geosys., 20, 148-165.
Schoene, B., Eddy, M.P., et al. (2019) Science, 363, 862-866.