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Reply to: Discussion of “Eocene to mid-Pliocene landscape evolution in Scandinavia inferred from offshore sediment volumes and pre-glacial topography using inverse modeling” (Pedersen et al. 2018, Geomorphology, 303: 467–485)

Pedersen, Vivi Kathrine, Braun, Jean, Huismans, Ritske S.
Geomorphology 2019 v.328 pp. 225-230
Eocene epoch, landscapes, models, sediments, topography, uncertainty, Scandinavia
Here we reply to the discussion paper by Rasmussen (2018). In his discussion, Rasmussen (2018) raises concern on the use of the offshore sediment record as a way of constraining sediment flux out of Scandinavia over time, in order to inform landscape evolution models. We acknowledge that this approach is associated with large uncertainties, particularly in relation to source areas outside of Scandinavia that may have contributed to the sediment volume, and potential sinks that lie outside of our study area. Based on the comments by Rasmussen (2018), we present now a new complimentary set of inversions that explores an alternative for the imposed sediment volume originating from Scandinavia. Specifically, we assume that a significantly smaller Eocene sediment volume originates from Scandinavia, and a larger uncertainty on sediment volumes from all the considered time periods. We find that a lower Eocene sediment flux from Scandinavia makes Cenozoic plateau uplift more compatible with the offshore sediment record. However, these new plateau scenarios result in large-scale topography that is even less compatible with our reconstructed mid-Pliocene landscape, compared to the previous peneplain scenarios presented in Pedersen et al. (2018). We still find the scenario with substantial initial topography best compatible with our mid-Pliocene landscape, although this scenario cannot match the offshore record to the same degree when a lower Eocene sediment flux is assumed.On a final note, we emphasize that our inverse modeling approach is designed to incorporate geological information directly into the modeling, which will reduce the gap between geological observations and modeling. We therefore welcome any additional information that can inform and improve our modeling approach. However, we are dependent on some level of quantification in order to incorporate geological observations and exploit the full potential of this approach.