Untersuchung des Potenzials eines noch ungeöffneten Bohrkerns vom Paläosee Idaho als Paläoklimaarchiv Nordamerikas im Plio- und Pleistozän
Zusammenfassung der Projektergebnisse
We have generated a new palynological record for the late Pliocene to early Pleistocene (c. 2.8–2.4 Ma) from drillcore material from paleo-Lake Idaho (northwestern USA). Dated via paleomagnetic reversals and augmented by quantitative pollen-based climate estimates, it provides new insight into the climate and ecosystem variability in northwestern North America during the intensification of Northern Hemisphere glaciation. Our data suggest that forest dynamics were predominantly driven by climate change, likely including glacial/interglacial variability, as a response to orbital obliquity forcing. Importantly, the new pollen data from paleo-Lake Idaho document a climatically driven forest biome change across the Plio/Pleistocene boundary, which is marked by the replacement of conifer-dominated forests by open mixed forests. This change is related to an increase in moisture availability. This is in agreement with the hypothesis that moisture transport to the high latitudes of North America increased at that time due to palaeoceanographic changes in the subarctic Pacific Ocean. In addition, the estimated timing of forest-composition change at paleo-Lake Idaho at ~ 2.6 Ma is consistent with the onset of ice-rafted debris deposition in the North Pacific and a surfacetemperature drop at the California Margin. Altogether, the close correspondence between our palynological data from paleo-Lake Idaho and marine proxy records from the NE Pacific suggests a close coupling of terrestrial ecosystem change in North America to Pacific Ocean circulation dynamics across the Plio/Pleistocene boundary.
Projektbezogene Publikationen (Auswahl)
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2019. Paleomagnetic and palynological investigations of a new Plio-Pleistocene drill core from paleolake Idaho (Northwestern United States). Joint IODP/ICDP Meeting, Cologne, Germany
Allstädt, F.J., Appel, E., Rösler, W., Prokopenko, A., Pross, J.
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2020. Downward remagnetization of a ~74 m thick zone in lake sediments from palaeo- Lake Idaho (NW United States) – Locating the Gauss/Matuyama geomagnetic boundary within a dual-polarity zone. Geophysical Journal International 222, 754-768
Allstädt, F.J., Appel, E., Rösler, W., Prokopenko, A., Neumann, U., Wenzel, T., Pross, J.
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2020. Reconstruction of environmental and climatic change during the late Pliocene and early Pleistocene in northwestern North America based on a new drill core from paleo-Lake Idaho. EGU General Assembly
Allstädt, F.J., Koutsodendris, A., Appel, E., Rösler, W., Prokopenko, A., Reichgelt, T., Pross, J.
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2021. Late Pliocene to early Pleistocene climate dynamics in western North America based on a new pollen record from paleo-Lake Idaho. Palaeobiodiversity and Palaeoenvironments 101, 177-195
Allstädt, F.J., Koutsodendris, A., Appel, E., Rösler, W., Reichgelt, T., Kaboth-Bahr, S., Prokopenko, A.A., Pross, J.
