Aptian giant explosive volcanic eruptions in the Songliao Basin and northeast Asia: A possible cause for global climate change and OAE-1a |
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| Institution: | 1. Institut für Geologie, Leibniz Universität Hannover, Callinstraβe 30, 30167 Hannover, Germany;2. Institut de Physique du Globe de Strasbourg, EOST, Université de Strasbourg, 1 rue Blessig, 67084 Strasbourg Cedex, France;3. Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, Universitätstrasse 150, 44801 Bochum, Germany;4. Department of Environment, Earth and Ecosystems, The Open University, Milton Keynes MK7 6AA, United Kingdom;5. Institut für Erd- und Umweltwissenschaften, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany;6. Institut de Géologie et Paléontologie, Université de Lausanne, Géopolis, 1015 Lausanne, Switzerland;1. South China Sea Culture Museum, Hainan Tropical Ocean University, 1 Yucai Road, Sanya 572022, China;2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, China;3. Department of Earth Sciences, The University of Hong Kong, Hong Kong Special Administrative Region |
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| Abstract: | Volcanism is a natural climate force that causes variations in temperatures. The Aptian Oceanic Anoxic Event 1a (OAE-1a) was preceded by a prominent negative C-isotope excursion attributed to major volcanism of the Ontong Java plateau (OJP), which presumably resulted in a pCO2 increase and a climatic change. However, the OJP alone may not adequately explain some important isotopic signatures such as the negative strontium-isotope excursion from 125 Ma to 113 Ma that is recorded in the corresponding marine deposits. We present an independent and hitherto undocumented case, the giant Aptian volcanism in the Songliao Basin and northeast Asia (SB-V) on the Cretaceous active continental margin between the Eurasian and the Pacific plates, which covered an area of ca. 2.3 × 106 km2, nearly matching the simultaneous case of the OJP. Intensive strong, explosive volcanic eruptions of the SB-V occurred at 121–109 Ma and introduced a large volume of fine-grained volcanic ash and degassing volatiles into the atmosphere. The Aptian isotopic ratios (87Sr/86Sr, 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb) of marine carbonates from the Mid-Pacific shift in values between their Barremian pre-excursion high values and the negative magmatic values of the SB-V. The transient global cooling at the onset of the OAE-1a coincided with the beginning of the violent acidic eruption of the SB-V (119.9–120.2 Ma). We therefore infer that the SB-V must have played a role in the Aptian global climatic changes and OAE-1a through the heavy fall of volcanic dust and the outgassing of aerosol and greenhouse gases. |
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| Keywords: | Cretaceous Songliao Basin Aptian volcanism in NE Asia Volcanic ash aerosol greenhouse gases Climate changes and OAE-1a Isotope excursion |
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