scholarly journals GEOMETRY OF HOLOCENE TIDAL NOTCHES – SEA LEVEL MARKERS AT PERACHORA PENINSULA, GULF OF CORINTH, GREECE

2017 ◽  
Vol 50 (1) ◽  
pp. 468
Author(s):  
S. Schneiderwind ◽  
M. Kázmér ◽  
S. Boulton ◽  
I. Papanikolaou ◽  
K. Reicherter
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Laser Scanning ◽  
Seismic Event ◽  
Tectonic Activity ◽  
Level Indicator ◽  
Mean Sea Level ◽  
Related Information ◽  
Gulf Of Corinth ◽  
Coastal Cliffs

Tidal notches are a generally accepted sea level indicator that, when different from mean sea level, witness tectonic activity at or near coastlines. However, how to infer related information is controversial since tectonic uplift from a single seismic event is not likely to exceed several decimetres. High resolution laser scanning offers the availability of close-up views on exposures and to detect evidence for multiple sea level indicators in between major emergence. Statistically representative profiles along exposure were analysed in order to prove for already described tidal notches and to highlight similar shapes in consistent geometries along coastal cliffs of Perachora Peninsula.

scholarly journals The effect of lateral variations in Earth structure on Last Interglacial sea level

2021 ◽  
Author(s):  
Jacqueline Austermann ◽  
Mark Hoggard ◽  
Konstantin Latychev ◽  
Fred Richards ◽  
Jerry Mitrovica
Keyword(s):  
Sea Level ◽  
Earth Structure ◽  
Last Interglacial ◽  
Level Indicator ◽  
Mean Sea Level ◽  
Mineral Physics ◽  
Shear Wave Speed ◽  
Global Mean Sea Level ◽  
Lateral Variations ◽  
Global Mean

It is generally agreed that the Last Interglacial (LIG; ~130-115ka) was a time when global average temperatures and global mean sea level were higher than they are today. However, the exact timing, magnitude, and spatial pattern of ice melt is much debated. One difficulty in extracting past global mean sea level from local observations is that their elevations need to be corrected for glacial isostatic adjustment (GIA), which requires knowledge of Earth’s internal viscoelastic structure. While this structure is generally assumed to be radially symmetric, evidence from seismology, geodynamics, and mineral physics indicates that large lateral variations in viscosity exist within the mantle. In this study, we construct a new model of Earth’s internal structure by converting shear wave speed into viscosity using parameterisations from mineral physics experiments and geodynamical constraints on Earth’s thermal structure. We use this 3D Earth structure, which includes both variations in lithospheric thickness and lateral variations in viscosity, to calculate the first 3D GIA prediction for LIG sea level. We find that the difference between predictions with and without lateral Earth structure can be meters to 10s of meters in the near field of former ice sheets, and up to a few meters in their far field. We demonstrate how forebulge dynamics and continental levering are affected by laterally varying Earth structure, with a particular focus on those sites with prominent LIG sea level records. Results from three 3D GIA calculations show that accounting for lateral structure acts to increase local sea level by up to ~1.5m at the Seychelles and minimally decrease it in Western Australia. We acknowledge that this result is only based on a few simulations, but if robust, this shift brings estimates of global mean sea level from these two sites into closer agreement with each other. We further demonstrate that simulations with a suitable radial viscosity profile can be used to locally approximate the 3D GIA result, but that these radial profiles cannot be found by simply averaging viscosity below the sea level indicator site.

A seasonal mean sea-level indicator

1960 ◽  
Vol 7 (1) ◽  
pp. 52-61 ◽  
Author(s):  
Jean Filloux ◽  
Gordon Groves
Keyword(s):  
Sea Level ◽  
Level Indicator ◽  
Mean Sea Level

scholarly journals Global Mean Sea Level: Indicator of Climate Change?

Science ◽  
1983 ◽  
Vol 219 (4587) ◽  
pp. 997-997 ◽  
Author(s):  
J. HANSEN ◽  
V. GORNITZ ◽  
S. LEBEDEFF ◽  
E. MOORE
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Level Indicator ◽  
Mean Sea Level ◽  
Global Mean Sea Level ◽  
Global Mean

New insights into sedimentary processes and related morphologies in tidal straits: the case of the Rio-Antirio Sill (Greece)

2021 ◽  
Author(s):  
Romain Rubi ◽  
Aurélia Hubert-Ferrari ◽  
Elias Fakiris ◽  
Dimitris Christodoulou ◽  
Xenophon Dimas ◽  
...  
Keyword(s):  
High Resolution ◽  
Tidal Currents ◽  
Internal Tides ◽  
Tectonic Activity ◽  
Depositional Model ◽  
Carbonate Production ◽  
Sea Floor ◽  
Bottom Currents ◽  
Gulf Of Corinth ◽  
Underwater Camera

<p>Straits are crossed by marine currents that are amplified due to the water constriction. These nearshore high-velocity flows are problematic for offshore infrastructures (bridge pillars, cables, pipelines etc), but constitute an under-estimated carbon-free kinematic energy source. Most of the straits are dominated by tidal currents which flow axially to the seaway, with reversal directions and phase difference between the two interlinked basins. These tidal currents interplay with: (i) sediment sources that also includes in situ carbonate production and deltas, (ii) tectonic activity, and (iii) inherited lowstand features, all shaping the sea floor into complex geomorphologies. Previous studies have highlighted a common tidal-strait depositional model with a strait-center zone in erosion and on each side a dune-bedded strait zone with 3D and 2D tidal dunes and tidal ripples.</p><p>Here, we present an alternative tidal-strait model based on an interdisciplinary approach using high-resolution geophysical and oceanographical data to better constrain the processes acting at the sea floor. We focus on the Rion-Antirion strait in Greece which controls the connection between the Gulf of Corinth and the Mediterranean Sea. Based on high-resolution multibeam bathymetry (MBES) over an area of 211km<sup>2</sup>, we identify and quantify the morphologies by extracting bathymetric swath profiles. These results are integrated with currents data (ADCP) and CTD profiles. In addition,  we use high-resolution Chirp subbottom profiles and high-resolution sparker seismic reflection profiles to document the stratigraphy and morphology of the sedimentary beds and erosional features. To complete this dataset, we use a towed underwater camera to image the sea-floor.</p><p>We define three zones, each characterized by common hydrodynamics, bedforms and morpho-bathymetric features which reveal an asymmetric strait. (1) The western zone is dominated by tectonics with salt diapirism and faults which interact with bottom currents to form erosional pools and ridge systems. (2) The strait center zone displays abrasion surfaces which consists on a rough rock-paved plateau surface encrusted by living red corals and sponges. Moreover, a moat cuts this plateau that localizes the sill at its eastern tip. This strait center area is dominated by inherited hard-ground fluviatile deposits which are abraded by bidirectional tidal-currents. (3) The eastern zone shows a deeper bathymetry with smoother features. The sediments are veneered on slopes forming plastered drifts and spits while the basin axis presents large chutes and pools. The bottom-currents in this zone, are related to internal tides from the Gulf of Corinth that are delayed with respect to the tidal currents. These internal-tide currents (3m/s) are three times faster than the oceanic tidal-currents in the strait (1m/s).</p><p>In conclusion, we document a tidal-strait system, which is interacting with active tectonics, and internal-tides along its axis. In results, Rion strait displays complex bathymetric features without any 3D or 2D tidal dunes. Thus, it provides a new end member to the tidal-strait depositional model. This end member is characterized by a re-localization of the erosion, bypass and deposition. It illustrates the key role of internal tides for straits located at the boundary between a confined deep-basin and the open-sea.</p>

Global Mean Sea Level: Indicator of Climate Change?

Science ◽  
1983 ◽  
Vol 219 (4587) ◽  
pp. 997-998 ◽  
Author(s):  
R. ETKINS ◽  
E. EPSTEIN
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Level Indicator ◽  
Mean Sea Level ◽  
Global Mean Sea Level ◽  
Global Mean

scholarly journals KONTRIBUSI PENTARIKHAN RADIOKARBON PERCONTOH TERUMBU KARANG PADA BATUGAMPING DI PANTAI SELATAN KABUPATEN WONOGIRI, JAWA TENGAH, TERHADAP NEOTEKTONIK KUARTER

2016 ◽  
Vol 6 (2) ◽  
Author(s):  
Prijantono Astjario ◽  
D.A. Siregar
Keyword(s):  
Coral Reef ◽  
Sea Level ◽  
Coastal Zone ◽  
Radiocarbon Dating ◽  
Tectonic Activity ◽  
Southern Coast ◽  
Uplift Rate ◽  
Mean Sea Level ◽  
Central Java ◽  
Active Tectonic

Wilayah pantai Ngungap, kawasan pesisir selatan Wonogiri, Jawa Tengah merupakan daerah jalur anjak dimana terumbu karang Kuarter tersingkap dari garis pantai hingga pebukitan tinggi. Enam undak laut terbentuk sejajar dengan garis pantai hingga mencapai ketinggian lebih dari 300 meter di atas muka laut. Hasil pentarikhan Radiokarbon tiga fosil terumbu karang dari undak laut termuda yang dapat berkontribusi terhadap perhitungan proses pengangkatan kawasan pantai Ngungap. Undak laut termuda menunjukan bahwa rata-rata aktivitas tektonik pengangkatan diwilayah pantai Ngungap, kawasan pesisir selatan Wonogiri adalah 5 mm/tahun. Pengangkatan rata-rata pesisir selatan Wonogiri jauh berbeda dengan kecepatan kawasan pantai-pantai tektonik aktif lainnya di Indonesia. Kata kunci : anjak, terumbu karang, undak laut, pentarikhan, pantai Ngungap Jawa Tengah The Ngungap coast of the southern coastal zone of Wonogiri, Central Jawa, situated in the central portion of the arcuate thrustbelt where Quaternary reefs show maximal elevation from coastline up to high hinterland. Six terraces have been formed parallel to the coast line and extensively exposed up to more than 300 meters above mean sea level. Three Radiocarbon dating of coral reef derived from the lowest terraces can be contributed to the uplift calculation in the Ngungap area. The lowest terrace alows uplifting tectonic activity in the coast of Ngungap in the order of 5 mm/years. The uplift rate of southern coast of Wonogiri is different to the rate of active tectonic coastal areas in the eastern Indonesian region. Keywords: thrustbelt, reef, terrace, dating, Ngungap coast of Central Java

scholarly journals Quaternary Evolution of Coastal Plain in Response to Sea-Level Changes: Example from South-East Sicily (Southern Italy)

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1524
Author(s):  
Salvatore Distefano ◽  
Fabiano Gamberi ◽  
Niccolò Baldassini ◽  
Agata Di Stefano
Keyword(s):  
High Resolution ◽  
Continental Shelf ◽  
Sea Level ◽  
Tectonic Activity ◽  
Research Approach ◽  
Coastal Environments ◽  
Sea Level Changes ◽  
Continental Shelves ◽  
Wide Range ◽  
Coastal Deposits

During a cycle of sea-level variation, coastal environments develop in different position of the continental shelf following seaward and landward shift of the coastline. They vary widely in character, reflecting the wide range of process-regimes that are brought about during the different stages of sea-level variations. Within this scenario, the morphology of continental shelves, mainly resulting from the combined effect of tectonic activity and eustatism, plays an important role in controlling the features and the preservation of coastal environments. Coastal deposits formed along continental shelves in the past, during different stages of sea-level changes, consist of discontinuous and thin depositional bodies, thus their reconstruction can be best carried out through the interpretation of high-resolution seismic data. Such a research approach is adopted in the present study to investigate a portion of the continental shelf of the southernmost sector of SE Sicily, in the offshore of Marzamemi village (Syracuse). The interpretation of high-resolution “Sparker” profiles allowed us to reconstruct the evolution of alluvial and lagoonal environments, established on a substratum of Pliocene or more ancient marine deposits, with the detection of several seismic units and unconformity surfaces, which have been related to alternating sedimentation and erosional processes, depicting the sea-level change framework of glacial-interglacial phases, from the late Pleistocene onward.

Seismic stratigraphy of the Vendean-Armorican platform of the French Atlantic shelf: new insights into the history of the North Atlantic ocean

2010 ◽  
Vol 181 (1) ◽  
pp. 37-50
Author(s):  
Pedro Huerta ◽  
Jean-Noël Proust ◽  
Pol Guennoc ◽  
Isabelle Thinon
Keyword(s):  
High Resolution ◽  
Atlantic Ocean ◽  
Sea Level ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Passive Margin ◽  
Tectonic Activity ◽  
Marine Deposits ◽  
The North ◽  
The North Atlantic

Abstract The evolution of the North-Atlantic Ocean from its rifting stage during the Upper Jurassic until the present-day passive margin is recorded by the sedimentary wedge of eastern French-Atlantic platform. The study of a dense network of high resolution seismic profiles on the Vendean-Armorican platform (VAP) obtained during INSU-CNRS cruise “Geovend”, led to the characterization of the architecture of the sediment wedge preserved between the coast and Armorican margin shelf edge. This sediment wedge lies on a substratum composed of metamorphic and magmatic rocks of Palaeozoic age (Ub). The sediment wedge comprises six seismic units (U1-U6) bounded by regional unconformities: Jurassic marine succession (U1), Upper Cretaceous marine rocks (U2), Eocene-Oligocene marine deposits of the incipient VAP (U3), Miocene (U4) and Plio-Quaternary (U5) marine deposits overlain by the last sea-level rise ravinement deposits (U6). Above the basal unconformity at the top of Ub, the units are bounded by angular unconformities (top of U1, U2, U3), truncation with channel incision (top U4) or planar marine ravinement (top of U5) surfaces. Most of these unconformities are due to the tectonic activity of the bay of Biscay during the Mesozoic including (1) the North Atlantic rifting during the Jurassic to Early Cretaceous, (2) the propagation of the ocean crust and counterclockwise rotation of the Iberian block during the Aptian-Albian to Coniacian (magnetic anomaly 33–34) producing troughs at the top of U1 filled by downlapping U2 sediment wedges, (3) the Alpine compression at the origin of folding and faulting and the unconformable deposition of U3, and (4) the late compressive deformation during the Miocene that affected U4. The VAP acquires its actual configuration during U4. Sedimentation on the platform was then affected by climatically-controlled relative sea-level changes (U5 to U6) that forced U5 shelf margin sediment deposition above an incised unconformity and subsequently overlain by U6 transgressive sediment blanketing. One of the main interest of the VAP area is the existence of pre- to post-rift units that helps to decipher with high resolution seismics the long-lived evolution of the Armorican margin. Such units are preserved because of the specific characters of this area located on the flank of the former Aquitaine basin (near the “celtaquitaine” flexure) and the presence of the Rochebonne basement high. The VAP thus displays most of the tectonosedimentary evolution of the West Atlantic margins. This paper would however constitute a basis for comparisons to other examples around the Atlantic ocean and then contribute to strengthen the running models of passive margin evolution.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

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