Temporary late Holocene barrier-chain deterioration due to insufficient sediment availability, Wadden Sea, Denmark

Geology ◽  
2020 ◽  
Author(s):  
Mikkel Fruergaard ◽  
Lasse Sander ◽  
Jérôme Goslin ◽  
Thorbjørn J. Andersen
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Wadden Sea ◽  
Sediment Cores ◽  
Regional Scale ◽  
Barrier Islands ◽  
Seismic Profiles ◽  
Littoral Drift ◽  
Data Set ◽  
Coastal Barrier

Understanding the coupling between sediment availability and sea-level change is important for forecasting coastal-barrier (barrier islands and barrier spits) response to future sea-level rise (SLR). An extensive data set of sediment cores, seismic profiles, and a high-resolution chronology from the Wadden Sea (southeastern North Sea) documents that long-term barrier-chain progradation was interrupted by a period of widespread barrier deterioration between ca. 3.5 and 2.0 ka. The decay of the barrier islands resulted from a decrease in littoral drift triggered by regional-scale coastal reconfiguration. The formation of a large cuspate foreland updrift caused the depositional locus to shift away from the barrier coast. Our results demonstrate that the resulting reduction in marine sediment availability substantially decreased the stability of the barrier chain, causing the regional SLR thresholds to fall from between 2 and 9 mm yr–1 to ~0.9 mm yr–1, and thus below contemporary rates of SLR. Hence, we argue that predicting the response of barrier coasts to ongoing SLR requires consideration of possible changes in sediment availability and the role of large-scale geomorphological feedbacks due to human and natural causes.

scholarly journals Standard geomagnetic observatory data in tectonomagnetism: case study related to the M 5.7 Timisoara, Romania, earthquake

1997 ◽  
Vol 40 (2) ◽  
Author(s):  
M. Popeskov
Keyword(s):  
Geomagnetic Field ◽  
Large Scale ◽  
Regional Scale ◽  
Extensive Study ◽  
Field Variation ◽  
Regional Effect ◽  
Data Set ◽  
Small Magnitude ◽  
Observatory Data ◽  
Set Up

There has recently been much discussion of large-scale interactions of fault zones and the influence of large-scale processes in the preparation and triggering of earthquakes. As a consequence, an official recommendation was issued to set up observational networks at regional scale. In this context, the existing network of standard geomagnetic observatories might play a more important role in future tectonomagnetic studies. The data from standard geomagnetic observatories are basically not appropriate for the detection of small-magnitude and, in most cases, spatially very localized geomagnetic field changes. However, their advantage is a continuity in a long-time period which enables the study of regional tectonomagnetic features and long-term precursory changes. As the first step of a more extensive study aimed at examining the features of observatory data for this purpose, a three-year data set from five European observatories has been analyzed. Some common statistical procedures have been applied along with a simple difference technique and multivariate linear regression to define local geomagnetic field changes. The distribution of M ³ 4.5 earthquakes in Europe, in a corresponding period, was also taken into account. No pronounced field variation, related in time to the M 5.7 Timisoara (Romania) earthquake on July 12, 1991, was found at Grocka observatory at about 80 km from the earthquake epicenter. However, an offset in level of the differences in declination which include Grocka observatory, not seen in the case of differences between other observatories, could be associated with a possible regional effect of the M 4.8 earthquake which occurred in September 1991 at about 70 km SE from Grocka.

Subsurface geological imaging of northeastern Tunisia during the middle to the upper Eocene: Insights from integrated geophysical interpretation

2021 ◽  
pp. 1-64
Author(s):  
Oussama Abidi ◽  
Kawthar Sebei ◽  
Adnen Amiri ◽  
Haifa Boussiga ◽  
Imen Hamdi Nasr ◽  
...  
Keyword(s):  
Sea Level ◽  
Regional Scale ◽  
Upper Eocene ◽  
Sea Level Changes ◽  
Seismic Profiles ◽  
Borehole Data ◽  
Third Order ◽  
Good Correspondence ◽  
Basin Inversion ◽  
Sea Level Fluctuations

The Middle to Upper Eocene series are characterized by multiple hiatuses related to erosion, non-deposition or condensed series in the Cap Bon and Gulf of Hammamet provinces. We performed an integrated study taking advantage from surface and subsurface geology, faunal content, borehole logs, electrical well logs, vertical seismic profiles and surface seismic sections. Calibrated seismic profiles together with borehole data analysis reveal unconformities with deep erosion, pinchouts, normal faulting and basin inversion which are dated Campanian, intra-Lutetian and Priabonian compressive phases; these events were also described at the regional scale in Tunisia. Tectonics, sea level fluctuations and climate changes closely controlled the depositional process during the Middle to Upper Eocene time. The depositional environment ranges from internal to outer platform separated by an inherited paleo-high. We determine eight third order sequences characterizing the interaction between tectonic pulsations, sea level changes and the developed accommodation space within the Middle to Upper Eocene interval. We correlate the obtained results of the Cap Bon-Gulf of Hammamet provinces with the published global charts of sea-level changes and we find a good correspondence across third order cycles. Model-based 3D inversion proved to be a solution to model the lateral and vertical lithological distribution of the Middle to Upper Eocene series.

Vulnerability of coastal areas to increased aquifer saturation due to climate change

2021 ◽  
Author(s):  
Alexandre Gauvain ◽  
Ronan Abhervé ◽  
Jean-Raynald de Dreuzy ◽  
Luc Aquilina ◽  
Frédéric Gresselin
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Large Scale ◽  
Regional Scale ◽  
Drainage System ◽  
Hydrological Regime ◽  
Coastal Areas ◽  
Western Coast ◽  
Study Sites ◽  
The Impact

<p>Like in other relatively flat coastal areas, flooding by aquifer overflow is a recurring problem on the western coast of Normandy (France). Threats are expected to be enhanced by the rise of the sea level and to have critical consequences on the future development and management of the territory. The delineation of the increased saturation areas is a required step to assess the impact of climate change locally. Preliminary models showed that vulnerability does not result only from the sea side but also from the continental side through the modifications of the hydrological regime.</p><p>We investigate the processes controlling these coastal flooding phenomena by using hydrogeological models calibrated at large scale with an innovative method reproducing the hydrographic network. Reference study sites selected for their proven sensitivity to flooding have been used to validate the methodology and determine the influence of the different geomorphological configurations frequently encountered along the coastal line.</p><p>Hydrogeological models show that the rise of the sea level induces an irregular increase in coastal aquifer saturations extending up to several kilometers inland. Back-littoral channels traditionally used as a large-scale drainage system against high tides limits the propagation of aquifer saturation upstream, provided that channels are not dominantly under maritime influence. High seepage fed by increased recharge occurring in climatic extremes may extend the vulnerable areas and further limit the effectiveness of the drainage system. Local configurations are investigated to categorize the influence of the local geological and geomorphological structures and upscale it at the regional scale.</p>

scholarly journals Regional-scale lateral carbon transport and CO<sub>2</sub> evasion in temperate stream catchments

2017 ◽  
Vol 14 (21) ◽  
pp. 5003-5014 ◽  
Author(s):  
Katrin Magin ◽  
Celia Somlai-Haase ◽  
Ralf B. Schäfer ◽  
Andreas Lorke
Keyword(s):  
Catchment Area ◽  
Large Scale ◽  
Net Primary Production ◽  
Spatial Scales ◽  
Regional Scale ◽  
Stream Network ◽  
Carbon Export ◽  
Data Set ◽  
Catchment Areas ◽  
Temperate Stream

Abstract. Inland waters play an important role in regional to global-scale carbon cycling by transporting, processing and emitting substantial amounts of carbon, which originate mainly from their catchments. In this study, we analyzed the relationship between terrestrial net primary production (NPP) and the rate at which carbon is exported from the catchments in a temperate stream network. The analysis included more than 200 catchment areas in southwest Germany, ranging in size from 0.8 to 889 km2 for which CO2 evasion from stream surfaces and downstream transport with stream discharge were estimated from water quality monitoring data, while NPP in the catchments was obtained from a global data set based on remote sensing. We found that on average 13.9 g C m−2 yr−1 (corresponding to 2.7 % of terrestrial NPP) are exported from the catchments by streams and rivers, in which both CO2 evasion and downstream transport contributed about equally to this flux. The average carbon fluxes in the catchments of the study area resembled global and large-scale zonal mean values in many respects, including NPP, stream evasion and the carbon export per catchment area in the fluvial network. A review of existing studies on aquatic–terrestrial coupling in the carbon cycle suggests that the carbon export per catchment area varies in a relatively narrow range, despite a broad range of different spatial scales and hydrological characteristics of the study regions.

Initial results from International Thwaites Glacier Collaboration cruise NBP20-02

2020 ◽  
Author(s):  
Robert Larter ◽  
Julia Wellner ◽  
Alastair Graham ◽  
Claus-Dieter Hillenbrand ◽  
Kelly Hogan ◽  
...  
Keyword(s):  
Sea Level ◽  
Numerical Models ◽  
Sediment Cores ◽  
Hot Water ◽  
Seismic Profiles ◽  
Ice Shelf ◽  
Regional Survey ◽  
Amundsen Sea ◽  
Marine Research ◽  
Initial Results

&lt;p&gt;Thwaites Glacier (TG) is more vulnerable to unstable retreat than any other part of the West Antarctic Ice Sheet. This is due to its upstream-dipping bed, the absence of a large ice shelf buttressing its flow and the deep bathymetric troughs that route relatively warm Circumpolar Deep Water (CDW) to its margin. Over the past 30 years the mass balance of TG has become increasingly negative, suggesting that unstable retreat may have already begun. The International Thwaites Glacier Collaboration (ITGC) is an initiative jointly funded by the US National Science Foundation and the Natural Environment Research Council in the UK to improve knowledge of the boundary conditions and drivers of change at TG in order improve projections of its future contribution to sea level. The ITGC is funding a range of projects that are conducting on-ice and marine research, and applying numerical models to utilize results in order to predict how the glacier will change and contribute to sea level over coming decades to centuries.&lt;/p&gt;&lt;p&gt;RV Nathaniel B Palmer cruise NBP20-02, taking place from January&amp;#173; to March 2020, will be the second ITGC multi-disciplinary research cruise, building on results from NBP19-02, which took place last year. Thwaites Offshore Research Project (THOR) aims during NBP20-02 include: extending the bathymetric survey in front of TG, collecting sediment cores at sites selected from the survey data, and acquiring high-resolution seismic profiles to determine the properties of the former bed of TG that is now exposed. The detailed bathymetric data will reveal the dimensions and routing of troughs that conduct CDW to the glacier front and will image seabed landforms that provide information about past ice flow and processes at the bed when TG was more extensive. The sediment cores, together with ones collected recently beneath the ice shelf via hot-water drilled holes, will be analysed to establish a history of TG retreat, subglacial meltwater release, and CDW incursions extending back over decades, centuries and millennia before the short instrumental record. Thwaites-Amundsen Regional Survey and Network Project (TARSAN) researchers will reach islands and ice floes via zodiac boats to attach satellite data relay loggers to Elephant and Weddell seals. The loggers record ocean temperature and salinity during the seals&amp;#8217; dives, greatly increasing the spatial extent and time span of oceanographic observations. In addition to work that is part of the THOR and TARSAN projects, another cruise objective is to recover and redeploy long-term oceanographic moorings in the Amundsen Sea. We will present initial results from NBP20-02.&lt;/p&gt;

scholarly journals Regional-scale lateral carbon transport and CO<sub>2</sub> evasion in temperate stream catchments

2017 ◽  
Author(s):  
Katrin Magin ◽  
Celia Somlai-Haase ◽  
Ralf B. Schäfer ◽  
Andreas Lorke
Keyword(s):  
Large Scale ◽  
Net Primary Production ◽  
Spatial Scales ◽  
Regional Scale ◽  
Water Quality Monitoring ◽  
Stream Network ◽  
Data Set ◽  
Mean Values ◽  
Catchment Areas ◽  
Temperate Stream

Abstract. Inland waters play an important role in regional to global scale carbon cycling by transporting, processing and emitting substantial amounts of carbon, which originate mainly from their catchments. In this study, we analyzed the relationship between terrestrial net primary production (NPP) and the rate at which carbon is exported from the catchments in a temperate stream network. The analysis included more than 200 catchment areas in southwest Germany, ranging in size from 0.8 to 889 km2 for which CO2 evasion from stream surfaces and downstream transport with stream discharge were estimated from water quality monitoring data, while NPP in the catchments was obtained from a global data set based on remote sensing. We found that on average 2.7 % of terrestrial NPP (13.9 g C m2 yr−1) are exported from the catchments by streams and rivers, in which both CO2 evasion and downstream transport contributed about equally to this flux. The average carbon fluxes in the catchments of the study area resembled global and large-scale zonal mean values in many respects, including NPP, stream evasion as well as the catchment-specific total export rate of carbon in the fluvial network. A review of existing studies on aquatic-terrestrial coupling in the carbon cycle suggests that the catchment-specific carbon export varies in a relatively narrow range, despite a broad range of different spatial scales and hydrological characteristics of the study regions.

scholarly journals Early Holocene sea-level changes in Øresund, southern Scandinavia

1969 ◽  
Vol 26 ◽  
pp. 29-32
Author(s):  
Ole Bennike ◽  
Martin Skov Andreasen ◽  
Jørn Bo Jensen ◽  
Matthias Moros ◽  
Nanna Noe-Nygaard
Keyword(s):  
Sea Level ◽  
Sediment Cores ◽  
Early Holocene ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Data Set ◽  
The North ◽  
Global Sea Level ◽  
The Baltic ◽  
Water Depths

The Baltic Sea and Kattegat are connected via three straits: Storebælt, Lillebælt and Øresund (Fig. 1). Øresund is the shallowest with a threshold around 7 m deep and increasing water depths to the north (Fig. 2). In the early Holocene, global sea-level rise led to reflooding of Øresund. It started in northern Øresund which was transformed into a fjord. However, so far the timing of the transgression has not been well determined, but sediment cores collected north of the threshold, at water depths of 12 to 20 m, and a new series of radiocarbon ages help to constrain this. As the relative sea level continued to rise, the threshold in Øresund was also flooded, and Øresund became a strait. In mid-Holocene time, the relative sea level rose until it was 4–5 m higher than at present, and low-lying areas around Øresund became small fjords. During the late Holocene, the relative sea level fell again. Part of the data set discussed here was presented by Andreasen (2005).

scholarly journals The Westernmost Mediterranean evolution: A review of the Alboran and Algero-Balearic basins stratigraphy

2020 ◽  
Author(s):  
Laura Gómez de la Peña ◽  
César Ranero ◽  
Eulàlia Gràcia ◽  
Guillermo Booth-Rea
Keyword(s):  
Tectonic Evolution ◽  
Large Scale ◽  
Regional Scale ◽  
Kinematic Model ◽  
Evolutionary Model ◽  
Entire Region ◽  
Seismic Profiles ◽  
Geodynamic Evolution ◽  
Entire Area ◽  
Regional Tectonic

&lt;p&gt;The Alboran Basin is the westernmost of the Mediterranean basins. It is composed of different sub-basins and connects toward the east with the Algero-Balearic Basin. Regional studies of these basins are mainly from the &amp;#180;90s, but the restricted seismic coverage and generally low quality (old acquisition and processing methods) of the seismic profiles were not enough to perform a detailed analysis of the entire sediment infill. More recent works characterize in detail a particular area, but the correlation between the different sub-basins remained beyond the scope of those works. Furthermore, these recent works are usually focused only on the Messinian and younger stratigraphy. Thus, the correlation of the sediment history across the entire region and its integration with the regional tectonic evolution has not been achieved. This results in a bunch of models, different for each sub-basin and not always coherent among them, which makes difficult the understanding of the geodynamic evolution of the region&lt;/p&gt;&lt;p&gt;Based on ~4500 km of new and reprocessed multichannel seismic profiles, together with well and dredge data, we are able to review the westernmost Mediterranean stratigraphy at a regional scale. We have correlated the sediment units deposited since the beginning of the formation of the different sub-basins, and we present for the first time a coherent stratigraphy and large-scale tectonic evolution of the whole region. The results provide the information to test and refine models of the geodynamic evolution of the westernmost Mediterranean.&lt;/p&gt;&lt;p&gt;The main objectives are: (i) To define a seismostratigraphy framework for the entire region, integrating previous interpretations and correlating the sedimentary units among depocentres; (ii) To propose an evolutionary model for each sub-basin; and (iii) To integrate all sub-basins results in an updated general kinematic model for the westernmost Mediterranean region.&lt;/p&gt;&lt;p&gt;Main results shed light on the particular evolution of each sub-basin as well as in the entire basin evolution. The Late Oligocene - Miocene represents the formation stage of the basins, controlled by the evolution of the Gibraltar subduction system. During this period, each sub-basin shows different sedimentary units, supporting differences in their evolution. The Plio-Quaternary corresponds to the deformation stage, driven by the Eurasian-African plates convergence. The Plio-Quaternary sediments are covering the entire area, instead of being restricted to the sub-basins. This latter period is characterized by contractional and strike-slip deformation, accommodated mainly by re-activation of pre-existing crustal structures.&lt;/p&gt;

scholarly journals Three variables are better than one: detection of european winter windstorms causing important damages

2014 ◽  
Vol 14 (4) ◽  
pp. 981-993 ◽  
Author(s):  
M.-S. Deroche ◽  
M. Choux ◽  
F. Codron ◽  
P. Yiou
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Insurance Industry ◽  
Surface Wind ◽  
Relative Vorticity ◽  
Reanalysis Data ◽  
Data Set ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Wind Speeds

Abstract. In this paper, we present a new approach for detecting potentially damaging European winter windstorms from a multi-variable perspective. European winter windstorms being usually associated with extra-tropical cyclones (ETCs), there is a coupling between the intensity of the surface wind speeds and other meso-scale and large-scale features characteristic of ETCs. Here we focus on the relative vorticity at 850 hPa and the sea level pressure anomaly, which are also used in ETC detection studies, along with the ratio of the 10 m wind speed to its 98th percentile. When analysing 10 events known by the insurance industry to have caused extreme damages, we find that they share an intense signature in each of the 3 fields. This shows that the relative vorticity and the mean sea level pressure have a predictive value of the intensity of the generated windstorms. The 10 major events are not the most intense in any of the 3 variables considered separately, but we show that the combination of the 3 variables is an efficient way of extracting these events from a reanalysis data set.

Sign in / Sign up

Export Citation Format

Share Document