A Standardized Database of Marine Isotope Stage 5a and 5c Paleo-Shoreline Indicators

2021 ◽  
Author(s):  
Schmitty B. Thompson ◽  
Jessica R. Creveling
Keyword(s):  
North America ◽  
Sea Level ◽  
Atlantic Coast ◽  
Ice Sheets ◽  
Climate Projections ◽  
Glacial Isostatic Adjustment ◽  
Last Interglacial ◽  
Comprehensive Overview ◽  
Isostatic Adjustment ◽  
The Caribbean

<p>Reconstructions of global mean sea level (GMSL) through interstadials such as Marine Isotope Stages (MIS) 5a and 5c provide important constraints on the rates of growth and collapse of major ice sheets during warm periods analogous to future climate projections. These reconstructions rely upon precisely dated geomorphic and sedimentological indicators for past sea level whose present elevations are complicated by tectonics and glacial isostatic adjustment (GIA). Compilations of MIS 5a and 5c paleo-sea level indicators that covering a wide geographic range can be used to minimize misfit with glacial isostatic adjustment models and thereby quantify and refine the convolved contribution of GMSL to the present elevation of paleo-shoreline indicators. Here we present a global compilation of previously published Marine Isotope Stages 5a and 5c local sea level indicators from 39 sites covering three main regions: the Pacific coast of North America, the Atlantic coast of North America and the Caribbean, and far field. We describe the standardized entry of these data into the World Atlas of Last Interglacial Shorelines (WALIS) database. Each entry within the MIS 5a and 5c WALIS database reproduces from the primary literature the indicator elevation, indicative meaning, and geochronology, along with a comprehensive overview of the literature for each site. While MIS 5a and 5c indicators sites are geographically widespread, these data are also patchy and preferentially represent the North American continent and the Caribbean and, hence, regions intermediate and far afield of the contemporaneous ice sheets. While this dataset will support future refinements to MIS 5a and 5c GMSL reconstructions arising from GIA modeling, it also motivates further data collection.</p>

scholarly journals A Global Database of Marine Isotope Stage 5a and 5c Marine Terraces and Paleoshoreline Indicators

2021 ◽  
Author(s):  
Schmitty B. Thompson ◽  
Jessica R. Creveling
Keyword(s):  
North America ◽  
Sea Level ◽  
Atlantic Coast ◽  
Marine Isotope Stage ◽  
Tectonic Deformation ◽  
Last Interglacial ◽  
Global Database ◽  
Isostatic Adjustment ◽  
Marine Terraces ◽  
Open Access Database

Abstract. In this review we compile and detail the elevation, indicative meaning, and chronology of Marine Isotope Stage 5a and 5c sea level indicators for 39 sites within three geographic regions: the Pacific coast of North America, the Atlantic coast of North America and the Caribbean, and the remaining globe. These relative sea level indicators, comprised of geomorphic indicators such as marine and coral reef terraces, eolianites, and sedimentary marine and terrestrial limiting facies, facilitate future investigation into Marine Isotope Stage 5a and 5c interstadial paleo-sea level reconstruction, glacial isostatic adjustment, and Quaternary tectonic deformation. The open access database, presented in the format of the World Atlas of Last Interglacial Shorelines (WALIS) database, can be found at https://doi.org/10.5281/zenodo.4426206 (Thompson and Creveling, 2021).

Reconciling geodetic and geologic estimates of coastal vertical land motion around the British Isles

2021 ◽  
Author(s):  
Makan A. Karegar ◽  
Simon E. Engelhart ◽  
Jürgen Kusche ◽  
Glenn A. Milne ◽  
Sarah L. Bradley
Keyword(s):  
North America ◽  
Sea Level ◽  
Land Surface ◽  
Atlantic Coast ◽  
Glacial Isostatic Adjustment ◽  
British Isles ◽  
Isostatic Adjustment ◽  
Vertical Land Motion ◽  
Precise Analysis ◽  
Holocene Sea Level

<p><em>Karegar et al</em>. (<em>2016</em>, <em>GRL</em>) showed that independent estimates of vertical land motion from geodetic and geologic techniques are critical for understanding coastal surface motion caused by geological versus human-induced processes along the Atlantic coast of North America. Motivated by these results, <span>w</span>e extend our analysis to the British Isles where good quality and spatially dense constraints are available from a continuous G<span>NSS</span> network and a state-of-the-art Holocene sea-level database. Glacial Isostatic Adjustment (GIA) along the Atlantic coast of North America causes the land surface to sink (up to -1.5 <em>mm/yr</em>), exacerbating tidal-induced flooding effects of sea-level rise. The British Isles are also subjected to proglacial forebulge collapse associated with the GIA response to the ancient Fennoscandian and British-Irish Ice Sheets. Here, we present an up-to-date and precise analysis based on continuous GNSS (combined GPS and GlONASS observations) and geologic records of late Holocene sea-level change to examine residuals between rates on these different timescales to determine if there is a significant residual and, if so, the processes responsible for the rate change.</p>

scholarly journals Glacial Isostatic Adjustment modelling: historical perspectives, recent advances, and future directions

2018 ◽  
Author(s):  
Pippa L. Whitehouse
Keyword(s):  
Solid Earth ◽  
Sea Level ◽  
Measurement Techniques ◽  
Ice Sheets ◽  
Order Effects ◽  
System Modelling ◽  
Glacial Isostatic Adjustment ◽  
Future Directions ◽  
Historical Perspectives ◽  
Isostatic Adjustment

Abstract. Glacial Isostatic Adjustment (GIA) describes the response of the solid Earth, the gravitational field, and consequently the oceans to the growth and decay of the global ice sheets. It is a process that takes place relatively rapidly, triggering 100 m-scale changes in sea level and solid Earth deformation over just a few tens of thousands of years. Indeed, the first-order effects of GIA could already be quantified several hundred years ago without reliance on precise measurement techniques and scientists have been developing a unifying theory for the observations for over 200 years. Progress towards this goal required a number of significant breakthroughs to be made, including the recognition that ice sheets were once more extensive, the solid Earth changes shape over time, and gravity plays a central role in determining the pattern of sea-level change. This article describes in detail the historical development of the field of GIA and an overview of the processes involved. Significant recent progress has been made as concepts associated with GIA have begun to be incorporated into parallel fields of research; these advances are discussed, along with the role that GIA is likely to play in addressing outstanding research questions within the field of Earth system modelling.

Parameters controlling mid-Holocene highstand in Glacial Isostatic Adjustment modelling

2021 ◽  
Author(s):  
Tanghua Li ◽  
Stephen Chua ◽  
Nicole Khan ◽  
Patrick Wu ◽  
Benjamin Horton
Keyword(s):  
Southeast Asia ◽  
Sea Level ◽  
Late Holocene ◽  
Ice Sheets ◽  
Thickness Variation ◽  
Glacial Isostatic Adjustment ◽  
Lithospheric Thickness ◽  
Isostatic Adjustment ◽  
Mantle Viscosity ◽  
Open Questions

<p>Holocene relative sea-level (RSL) records from regions distal from ice sheets (far-field) are commonly characterized by a mid-Holocene highstand, when RSL reached higher than present levels. The magnitude and timing of the mid-Holocene highstand varies spatially due to hydro-isostatic processes including ocean syphoning and continental levering. While there are open questions regarding the timing, magnitude and source of ice-equivalent sea level in the middle to late Holocene.</p><p>Here, we compare Glacial Isostatic Adjustment (GIA) model predictions to a standardized database of sea-level index points (SLIPs) from Southeast Asia where we have near-complete Holocene records. The database has more than 130 SLIPs that span the time period from ~9.5 ka BP to present. We investigate the sensitivity of mid-Holocene RSL predictions to GIA parameters, including the lateral lithospheric thickness variation, mantle viscosity (both 1D and 3D), and deglaciation history from different ice sheets (e.g., Laurentide, Fennoscandia, Antarctica).</p><p>We compute gravitationally self-consistent RSL histories for the GIA model with time dependent coastlines and rotational feedback using the Coupled Laplace-Finite Element Method. The preliminary results show that the timing of the highstand is mainly controlled by the deglaciation history (ice-equivalent sea level), while the magnitude is dominated by Earth parameters (e.g., lithospheric thickness, mantle viscosity). We further investigate whether there is meltwater input during middle to late Holocene and whether the RSL records from Southeast Asia can reveal the meltwater source, like Antarctica.</p>

Glacial Isostatic Adjustment with 3D Earth models: A comparison of case studies of deglacial relative sea level records of North America and Russian Arctic

2020 ◽  
Author(s):  
Tanghua Li ◽  
Nicole Khan ◽  
Simon Engelhart ◽  
Alisa Baranskaya ◽  
Peltier William ◽  
...  
Keyword(s):  
North America ◽  
Sea Level ◽  
3D Models ◽  
Viscosity Model ◽  
Glacial Isostatic Adjustment ◽  
Russian Arctic ◽  
Scaling Factors ◽  
Relative Sea Level ◽  
Isostatic Adjustment ◽  
Best Fit

<p>The Canadian landmass of North America and the Russian Arctic were covered by large ice sheets during the Last Glacial Maximum, and have been key areas for Glacial Isostatic Adjustment (GIA) studies. Previous GIA studies have applied 1D models of Earth’s interior viscoelastic structure; however, seismic tomography, field geology and recent studies reveal the potential importance of 3D models of this structure. Here, using the latest quality-controlled deglacial sea-level databases from North America and the Russian Arctic, we investigate the effects of 3D structure on GIA predictions. We explore scaling factors in the upper mantle (<em>β<sub>UM</sub></em>) and lower mantle (<em>β<sub>LM</sub></em>) and the 1D background viscosity model (<em>η<sub>o</sub></em>) with predictions of of the ICE-6G_C (VM5a) glaciation/deglaciation model of Peltier et al (2015, JGR) in these two regions, and compare with the best fit 3D viscosity structures.</p><p>We compute gravitationally self-consistent relative sea-level histories with time dependent coastlines and rotational feedback using both the Normal Mode Method and Coupled Laplace-Finite Element Method. A subset of 3D GIA models is found that can fit the deglacial sea-level databases for both regions. These databases cover both the near and intermediate field regions. However, North America and Russian Arctic prefer different 3D structures (i.e., combinations of (<em>η<sub>o</sub>, β<sub>UM</sub>, β<sub>LM</sub></em>)) to provide the best fits. The Russian Arctic database prefers a softer background viscosity model (<em>η<sub>o</sub></em>), but larger scaling factors (<em>β<sub>UM</sub>, β<sub>LM</sub></em>) than those preferred by the North America database.</p><p>Outstanding issues include the uncertainty of the history of local glaciation history. For example, preliminary modifications of the ice model in Russian Arctic reveal that the misfits of 1D models can be significantly reduced, but still fit less well than the best fit 3D GIA model.An additional issue concerns the extent to which the 3D models are able to improve both fits in North America and Russian Arctic when compared with 1D internal structure (ICE-6G_C VM5a & ICE-7G VM7), will be assessed in a preliminary fashion.</p>

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