Paleoclimate evolution of the NW-Pacific over the past 25Ma
Final Report Abstract
The Kuroshio and Oyashio Currents are major western boundary currents of the NW Pacific Ocean. They are mainly responsible for the latitudinal transport of heat and moisture and their variation on glacial/interglacial cycles imparts a major control on the climate evolution of eastern Asia. In this study, we investigated spatiotemporal variations in the strength and flow path of both ocean currents using deep-sea sediments collected during IODP Expeditions 333 (NanTroSEIZE Stage 2: Subduction Inputs 2 and Heat Flow) and 350 (Izu-Bonin-Mariana Rear Arc) in order to reconstruct changes in the climate evolution of the NW Pacific Ocean from the late Miocene to present. The lipid paleothermometers TEXH86, UK’37 and LDI indicate a long-term cooling trend from the Miocene to the Pleistocene followed by a gradual warming during the Holocene. In addition, our combined temperature records also provide evidence for periods of extensive warming during the late Miocene and mid- Pliocene as well as significant cooling that starts in the late Pliocene and cumulates in the glacial/interglacial cyclicity of the Pleistocene. Distributions of long-chain n-alkyl lipids indicate climate-driven changes of the paleovegetation cover in eastern Asia with a significant decline of deciduous trees and expansion of grasslands from the late Miocene to the Pleistocene. Variations in the abundances of nonacosan-10-ol also indicate the spread of a conifer-like vegetation during glacial periods and significant changes in the abundance of dust input and flow path pattern of the Kuroshio Current between both study sites. Our results thus provide evidence for a close coupling between oceanic and atmospheric transport as well as paleovegetation changes in the NW Pacific in response to climate variations and offers a perspective on vegetation and ecosystem changes that are to be expected in East Asia in a warmer-than-present world.
Publications
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(2016) Late Pliocene to Holocene spatiotemporal variation in the flow path of the Kuroshio Current (NW Pacific). IODP/ICDP Colloquium, Heidelberg, Germany
Jonas, A.S., Schwark, L., Bauersachs, T.
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(2016) Late Pliocene to Holocene spatiotemporal variation in the flow path of the Kuroshio Current. IODP Expedition 350 Post-cruise Meeting, Marrakesh, Morocco
Jonas, A.S., Schwark, L., Bauersachs, T.
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(2017) Impact of climate change on the magnetic mineral assemblage in marine sediments from Izu rear arc, NW Pacific Ocean, over the last 1 Myr. Palaeogeography, Palaeoclimatology, Palaeoecology 480, 53-69
Kars, M., Musgrave, R.J., Kodama, K., Jonas, A.S., Bordiga, M., Ruebsam, W., Vautravers, M., Bauersachs, T.
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(2017) Late Quaternary water temperature variations of the Northwest Pacific based on the lipid paleothermometers TEXH86, UK’37 and LDI. Deep Sea Research I 125, 81-93
Jonas, A.S., Schwark, L., Bauersachs, T.
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(2017) Mid-Pleistocene to Holocene evolution of the Kuroshio Current, Northwest Pacific Ocean. 28th International Meeting on Organic Geochemistry, Florence, Italy
Jonas, A.S., Schwark, L., Bauersachs, T.
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(2017) Variation in the flow path of the Kuroshio Current and its impact on NW Pacific paleoclimate evolution. IODP/ICDP Colloquium, Braunschweig, Germany
Jonas, A.S., Schwark, L., Bauersachs, T.
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(2018) Magnetic mineral diagenesis in a high temperature and deep methanic zone in Izu Rear Arc marine sediments, NW Pacific Ocean. Journal of Geophysical Research – Solid Earth 123, 8331-8348
Kars, M., Musgrave, R.J., Hoshino, T., Jonas, A.S., Bauersachs, T., Inagaki, F., Kodama, K.
