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  • 1
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    A Holocene relative sea-level database for the Baltic Sea (2021)
    GFZ Data Services
    Details
    Publication Date: 2021-08-19
    Description: Abstract
    Description: We present a compilation and analysis of 1099 Holocene relative shore-level (RSL) indicators including 867 relative sea-level data points and 232 data points from the Ancylus Lake and the following transitional phase from 10.7 to 8.5 ka BP located around the Baltic Sea. The spatial distribution covers the Baltic Sea and near-coastal areas fairly well, but some gaps remain mainly in Sweden. RSL data follow the standardized HOLSEA format and, thus, are ready for spatially comprehensive applications in, e.g., glacial isostatic adjustment (GIA) modelling. Sampling method The data set is a compilation of rather different samples from geological, geomorphological and archaeological studies. Most of the data was already published in different formats. In this compilation we homogenized the meta information of the available information according to the HOLSEA database format, https://www.holsea.org/archive-your-data, which is a modification of the recommendations given in Hijma et al. (2015). In addition to the reformatting, the majority of samples with radiocarbon dating were recalibrated with oxcal-software using the calib13 and marine13 curves. Furthermore, all sample descriptions were critically checked for consistency in positioning, levelling and indicative meaning by experts of the respective geographic region see Supplement 2. Analytical method In principle, it is a compilation, recalibration and revision of already published data. Data Processing Data of individual compilations were revised and imported into a relational database system. Therein, the data was transferred into the HOLSEA format by specified rules. By this procedure, a homogeneous categorisation was achieved without losing the original data. Also this is stored in the relational database system allowing for later updates of the transfer procedure or a recalibration of the data. Description of data table HOLSEA-baltic-yymmdd.xlsx The workbook in excel format contains 5 sheets, see https://www.holsea.org/archive-your-data: · Long-form, containing the complete information available for each sample · Short-form, a subset of attributes of the Long-form sheet · Radiocarbon, containing the radiocarbon dating information of the respective samples · U-series, a corresponding table containing the respective information of Uranium dating · References, a complete reference list of the primary publications in which the individual data sampling is described. All online sources for the compilation are included in the metadata. A full list of source references is provided in the data description file.
    Keywords: Baltic Sea ; sea-level indicator ; relative sea level ; HOLSEA ; glacial isostatic adjustment ; ice history model ; mapping function ; postgreSQL ; compound material 〉 sedimentary material 〉 sediment ; EARTH SCIENCE 〉 OCEANS 〉 COASTAL PROCESSES 〉 SHORELINES ; environment 〉 natural environment 〉 coastal environment ; In Situ Land-based Platforms 〉 FIELD SURVEYS ; In Situ/Laboratory Instruments 〉 Corers 〉 CORING DEVICES ; Phanerozoic 〉 Cenozoic 〉 Quaternary 〉 Holocene
    Type: Dataset , Dataset
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    DATA GFZ
  • 2
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    A statistical method to validate reconstructions of late-glacial relative sea level – Application to shallow water shells rated as low-grade sea-level indicators (2018)
    Copernicus
    Details
    Publication Date: 2018-06-01
    Description: In this study, we propose a statistical method to validate sea-level reconstructions using geological records known as sea-level indicators (SLIs). SLIs are often the only available data to retrace late-glacial relative sea level (RSL). Determining the RSL from SLI height is not straight forward, the elevation at which an SLI was found usually does not represent the past RSL. In contrast, it has to be related to past RSL by investigating sample’s type, habitat and deposition conditions. For instance, water distribution at which a specific specimen is found today can be related to the indicator's depositional height range. Furthermore, the precision of dating varies between geological samples, and, in case of radiocarbon dating, the age has to be calibrated using a non-linear calibration curve. To avoid an a-priori assumption like normal-distributed uncertainties, we define likelihood functions which take into account the indicative meaning’s available error information and calibration statistics represented by joint probabilities. For this conceptional study, we restrict ourselves to one type of indicators, shallow-water shells, which are usually considered as low-grade samples giving only a lower limit of former sea level, as the depth range in which they live spreads over several tens of meters, and does not follow a normal distribution. The presented method is aimed to serve as a strategy for glacial isostatic adjustment reconstructions, in this case for the German Paleo-Climate Modelling Initiative PalMod (https://www.palmod.de/en) and by extending it to other SLI types.
    Print ISSN: 1814-9340
    Electronic ISSN: 1814-9359
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 3
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    Dependence of late glacial sea-level predictions on 3D Earth structure (2020)
    In:  [Talk] In: EGU General Assembly 2020, 03.05.-08.05.2020, Online .
    Details
    Publication Date: 2021-05-04
    Description: Glacial isostatic adjustment is dominated by Earth rheology resulting in a variability of relative sea-level (RSL) predictions of more than 100 meters during the last glacial cycle. Seismic tomography models reveal significant lateral variations in seismic wavespeed, most likely corresponding to variations in temperature and hence viscosity. Therefore, the replacement of 1D Earth structures by a 3D Earth structure is an essential part of recent research to reveal the impact of lateral viscosity contrasts and to achieve a more consistent view on solid-Earth dynamics. Here, we apply the VIscoelastic Lithosphere and MAntle model VILMA to predict RSL during the last deglaciation. We create an ensemble of geodynamically constrained 3D Earth structures which is based on seismic tomography models while considering a range of conversion factors to transfer seismic velocity variations into viscosity variations. For a number of globally distributed sites, we discuss the resulting variability in RSL predictions, compare this with regionally optimized 1D Earth structures, and validate the model results with relative sea-level data (sea-level indicators). This study is part of the German Climate Modeling initiative PalMod aiming the modeling of the last glacial cycle under consideration of a coupled Earth system model, i.e. including feedbacks between ice-sheets and the solid Earth.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 4
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    A statistical method to validate reconstructions of late-glacial relative sea level – Application to shallow water shells rated as low-grade sea-level indicators (2018)
    Copernicus
    In:  Climate of the Past Discussions . pp. 1-17.
    Details
    Publication Date: 2018-09-12
    Description: In this study, we propose a statistical method to validate sea-level reconstructions using geological records known as sea-level indicators (SLIs). SLIs are often the only available data to retrace late-glacial relative sea level (RSL). Determining the RSL from SLI height is not straight forward, the elevation at which an SLI was found usually does not represent the past RSL. In contrast, it has to be related to past RSL by investigating sample’s type, habitat and deposition conditions. For instance, water distribution at which a specific specimen is found today can be related to the indicator's depositional height range. Furthermore, the precision of dating varies between geological samples, and, in case of radiocarbon dating, the age has to be calibrated using a non-linear calibration curve. To avoid an a-priori assumption like normal-distributed uncertainties, we define likelihood functions which take into account the indicative meaning’s available error information and calibration statistics represented by joint probabilities. For this conceptional study, we restrict ourselves to one type of indicators, shallow-water shells, which are usually considered as low-grade samples giving only a lower limit of former sea level, as the depth range in which they live spreads over several tens of meters, and does not follow a normal distribution. The presented method is aimed to serve as a strategy for glacial isostatic adjustment reconstructions, in this case for the German Paleo-Climate Modelling Initiative PalMod (https://www.palmod.de/en) and by extending it to other SLI types.
    Type: Article , NonPeerReviewed
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  • 5
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    Einfluss von lateralen Variationen in der Erdstruktur auf Meeresspiegelrekonstruktionen: Modelle zur glazial-isostatischen Anpassung in Oregon und Patagonien (2021)
    Details
    Publication Date: 2022-03-18
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 6
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    3D glacial-isostatic adjustment models using geodynamically constrained Earth structures (2021)
    Details
    Publication Date: 2022-03-21
    Description: The interaction between ice sheets and the solid Earth plays an important role for ice-sheet stability and sea-level change and hence for global climate models. Glacial-isostatic adjustment (GIA) models enable simulation of the solid Earth response due to variations in ice-sheet and ocean loading and prediction of the relative sea-level change. Because the viscoelastic response of the solid Earth depends on both ice-sheet distribution and the Earth’s rheology, independent constraints for the Earth structure in GIA models are beneficial. Seismic tomography models facilitate insights into the Earth’s interior, revealing lateral variability of the mantle viscosity that allows studying its relevance in GIA modeling. Especially, in regions of low mantle viscosity, the predicted surface deformations generated with such 3D GIA models differ considerably from those generated by traditional GIA models with radially symmetric structures. But also, the conversion from seismic velocity variations to viscosity is affected by a set of uncertainties. Here, we apply geodynamically constrained 3D Earth structures. We analyze the impact of conversion parameters (reduction factor in Arrhenius law and radial viscosity profile) on relative sea-level predictions. Furthermore, we focus on exemplary low-viscosity regions like the Cascadian subduction zone and southern Patagonia, which coincide with significant ice-mass changes.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 7
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    3D glacial-isostatic adjustment models using geodynamically constrained Earth structures (2021)
    Details
    Publication Date: 2022-03-21
    Description: The interaction between ice sheets and the solid Earth plays an important role for ice-sheet stability and sea-level change and hence for global climate models. Glacial-isostatic adjustment (GIA) models enable simulation of the solid Earth response due to variations in ice-sheet and ocean loading and prediction of the relative sea-level change. Because the viscoelastic response of the solid Earth depends on both ice-sheet distribution and the Earth’s rheology, independent constraints for the Earth structure in GIA models are beneficial. Seismic tomography models facilitate insights into the Earth’s interior, revealing lateral variability of the mantle viscosity that allows studying its relevance in GIA modeling. Especially, in regions of low mantle viscosity, the predicted surface deformations generated with such 3D GIA models differ considerably from those generated by traditional GIA models with radially symmetric structures. But also, the conversion from seismic velocity variations to viscosity is affected by a set of uncertainties. Here, we apply geodynamically constrained 3D Earth structures. We analyze the impact of conversion parameters (reduction factor in Arrhenius law and radial viscosity profile) on relative sea-level predictions. Furthermore, we focus on exemplary low-viscosity regions like the Cascadian subduction zone and southern Patagonia, which coincide with significant ice-mass changes.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 8
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    3D Earth structures for glacial-isostatic adjustment models (2021)
    GFZ Data Services
    Details
    Publication Date: 2023-12-09
    Description: Abstract
    Description: We provide 18 3D Earth structures on a global grid. This supplementary material of the manuscript includes (1) 18 netcdf files of the 3D Earth structures and (2) 72 figures that visualize the lithospheric thickness, lateral average viscosity of the asthenosphere, transition zone and upper mantle for all 18 3D Earth structures. The Earth structures were derived from seismic tomography models (Schaeffer & Lebedev 2013, 2010 update of Grand 2002) and, under consideration of geodynamic constrains, transferred to viscosity (Steinberger 2016, Steinberger & Calderwood 2006). The 18 Earth structures vary in conversion from seismic velocity to viscosity. Detailed description of the procedure can be found in the corresponding manuscript (Bagge et al. 2020a), where the Earth structure data were applied to the glacial-isostatic adjustment model VILMA (Klemann et al. 2008, 2015, Martinec et al. 2018) to predict the relative sea-level during the last deglaciation. The netCDF files are provided on a Gaussian grid of 256x512 grid points. Each Earth structure consist of 167 layers, while lateral variations in Earth structure are considered for 114 layers between surface and 870 km depth and radially symmetric layers are considered for 50 layers from 870 km to the Earth’s core. The Earth structure is given as logarithmic viscosity in log10[Viscosity(Pa s)]. To visualize the global 3D structures, we calculated the lithospheric thickness and average viscosity of the asthenosphere, upper mantle and transition zone. The lithospheric thickness is defined as minimum depth with a viscosity 〈 10^23.5 Pa s, the asthenosphere is defined between the base of the lithosphere and 225 km depth, the upper mantle between 225 km and 410 km and the transition zone between 410 km and 670 km depth.
    Keywords: laterally varying Earth structure ; glacial-isostatic adjustment ; EARTH SCIENCE 〉 SOLID EARTH 〉 GEOMORPHIC LANDFORMS/PROCESSES 〉 GLACIAL PROCESSES 〉 CRUST REBOUND ; EARTH SCIENCE 〉 SOLID EARTH 〉 GEOMORPHIC LANDFORMS/PROCESSES 〉 GLACIAL PROCESSES 〉 GLACIER CRUST SUBSIDENCE
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    DATA GFZ
  • 9
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    Predicted relative sea-level and sea-level data for validation (2020)
    GFZ Data Services
    Details
    Publication Date: 2023-12-09
    Description: Abstract
    Description: We provide the model results of the manuscript "Glacial-isostatic adjustment models using geodynamically constrained 3D Earth structures" (Bagge et al. 2020, Paper) including the (1) predicted relative sea-level and (2) applied sea-level data. The predicted relative-sea level is calculated with the VIscoelastic Lithosphere and MAntle model VILMA (Klemann et al. 2008, 2015, Martinec et al. 2018, Hagedoorn et al. 2007, Martinec & Hagedoorn 2005, Kendall et al. 2005). The glacial-isostatic adjustment models uses different Earth structures (3D, 1D global mean and 1D regionally adapted; Bagge et al. 2020, Paper; Bagge et al. 2020, https://doi.org/10.5880/GFZ.1.3.2020.004) and ice histories (ICE-5G, Peltier 2004; ICE-6G, Peltier et al. 2015, Argus et al. 2014; NAICE, Gowan et al. 2016) resulting in 44 3D models, 54 1D global mean models and 162 1D regionally adapted models. For more information on model description and input data see Bagge et al. (2020, Paper) and Bagge at al. (2020, https://doi.org/10.5880/GFZ.1.3.2020.004). The provided output data include (1a) the global distribution of predicted relative-sea level at 14 kilo years before present as ensemble range of the 3D GIA models for three ice histories as netCDF files, (1b) the predicted relative-sea level at eight locations at 14 kilo years before present for all models as ASCII file and (1c) the predicted relative sea-level for the deglaciation period for all models as ASCII files. Eight locations include Churchill, Angermanland, Ross Sea (Antarctica), San Jorge Gulf (Patagonia), Central Oregon Coast, Rao-Gandon Area (Senegal), Singapore and Pioneer Bay (Queensland, Australia). (2) The about 520 applied sea-level data provide information on time, relative sea-level and type of sea-level data. They are extracted for the eight locations from the GFZ database using SLIVisu (Unger et al. 2012, 2018) and provided as ACSII files.
    Keywords: laterally varying Earth structure ; glacial-isostatic adjustment ; relative sea-level ; VIscoelastic Lithosphere and MAntle model ; VILMA ; EARTH SCIENCE SERVICES 〉 MODELS 〉 CRYOSPHERE MODELS ; EARTH SCIENCE SERVICES 〉 MODELS 〉 GEOLOGIC/TECTONIC/PALEOCLIMATE MODELS
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    DATA GFZ
  • 10
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    A method for validation of GIA models using sea-level data with applications to Hudson Bay and SW Fennoscandia (2021)
    Details
    Publication Date: 2024-02-07
    Description: Glacial isostatic adjustment (GIA) is the ongoing response of the viscoelastic solid Earth, oceans and the gravitational field to the previous burden of the ice loads. The Earth’s surface was once covered with massive ice sheets, and melting of these ice sheets is still reshaping coastlines and affecting sea-level. To reconstruct former sea level and be able to predict future changes, it is necessary to constrain the rheological properties of the Earth’s structure. Widely used data to constrain Earth’s interior are sea-level indicators. In the first part of the thesis, we propose a statistical method that quantifies a relationship between the sea-level indicator and a relative sea level in order to compare it to GIA predictions. A statistical method is based on consideration of spatial and temporal probability density functions, derived from the age and elevation of each indicator. This method allows a more rigorous approach to validation with sea-level data and possibility to include low-quality data. We verified method performance in the Hudson Bay, Canada as a test run before applying it to the SW Fennoscandia. SW Fennoscandia identifies as an area where lateral heterogeneity is likely to exist. The south-western part of Fennoscandia lies on the crustal boundary called the Trans-European Suture Zone (TESZ), or the Tornquist Zone. GIA models have two representations of Earth’s structure; radially symmetric (1D), where the rheology only varies vertically, and lateral or 3D variations of viscosity structure. In this thesis, we compare glacial isostatic adjustment reconstructions with both representations of the rheology. Results from the 1D model show variations in the viscosity structure between the area near to the centre of the former ice sheet and the areas at the margin of the ice sheet. Hence, we verify the importance of including lateral variations in GIA models in this region. Application of 3D models displays the sensitivity of model parameters to crustal deformation. German Baltic coast yields thinner lithosphere than TESZ region and near-centre region. Additionally, in the TESZ region, we notice a steep increase in viscosity of the asthenosphere and upper-mantle. Furthermore, we compared two different global ice histories (ICE5G and ICE6G_C) and concluded that the marginal areas are more sensitive to different deglaciations, and we propose to use regional ice histories to constrain GIA models better. Apart from the new statistical method, this study sets a ground for future GIA studies in complex tectonic regions and demonstrates the importance of including laterally heterogeneous Earth structure in GIA models.
    Type: Thesis , NonPeerReviewed
    Format: text
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