PP027-05
Middle Miocene continental temperature and precipitation changes recorded in paleosol carbonates (a transatlantic approach)

Thursday, 10 December 2020: 19:16
Virtual
Katharina Methner1, C Page Chamberlain2, Catherine Badgley3, David Bajnai4, Jens Fiebig5, Emilija Krsnik6, Niklas Löffler7, Katharine M Loughney3 and Andreas Mulch8, (1)Stanford University, Stanford, United States, (2)Stanford University, Stanford, CA, United States, (3)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (4)University of Cologne, Köln, Germany, (5)Goethe University, Institute of Geosciences, Frankfurt (Main), Germany, (6)Senckenberg Biodiversity and Climate Research Center, Frankfurt, Germany, (7)Senckenberg Biodiversity and Climate Research Centre, Frankfurt (Main), Germany, (8)Senckenberg Biodiversity and Climate Research Centre, Frankfurt, Germany
Recorded Presentation
Abstract:
The middle Miocene offers the opportunity to study a period major global change during the global warm period of the middle Miocene Climatic Optimum (MCO) and the subsequent high-latitudinal cooling and Antarctic ice sheet expansion during the middle Miocene Climate Transition (MMCT). We investigate coupled temperature and precipitation change during this dynamic period through the integration of combined paleosol carbonate stable (δ18O, δ13C) and clumped (Δ47) isotope data with sedimentological and paleontological information.

Paleosol Δ47-temperature records from Central and Southern Europe (Switzerland, Spain) show strong similarities with marine records from the North Atlantic, pointing to the important role of the North Atlantic climate and ocean circulation dynamics for temperature and rainfall patterns in Europe (already) during the middle Miocene. In contrast, paleosol isotope data from high-elevation intermontane basins in the Northern Rocky Mountains (MT/ID, USA) show generally cooler (16 to 25°C) and rather constant temperatures throughout the MCO compared to the European record (24 to 38°C). The absence of the marine-terrestrial coupling as observed in the European records suggests that the topographically and hydrologically distinct settings of these sites, compared to the low-elevation (foreland) basins in Europe with closer proximity to the moisture source(s), may suppress global climatic change in favor of more local climatic controls at these high-elevation inland sites. In order to test this hypothesis, we investigate the well-dated sediments of the Barstow Formation (CA, USA) as a low-elevation, near-coastal counterpart to the Northern Rocky Mountain record. Our preliminary data show elevated paleosol Δ47-temperatures (and d18Osoil water values) during the MCO, which decrease thereafter, suggesting Barstow paleosols record the global pattern of middle Miocene climate change.

As current knowledge suggests that there is a strong regional differentiation of climate change impacts on the hydrological cycle, we aim for a multi-site (regional to continental) approach to establish regional paleotemperature patterns, identify driving factors of stable isotope in precipitation variability and ultimately quantify hydrological change during the MCO and the subsequent MMCT.

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