scholarly journals Review article: Extreme marine events revealed by lagoonal sedimentary records in Ghar El Melh during the last 2500 years in the northeast of Tunisia

2021 ◽  
Vol 21 (12) ◽  
pp. 3645-3661
Author(s):  
Balkis Samah Kohila ◽  
Laurent Dezileau ◽  
Soumaya Boussetta ◽  
Tarek Melki ◽  
Nejib Kallel
Keyword(s):  
High Resolution ◽  
Sediment Cores ◽  
Storm Events ◽  
Sedimentary Records ◽  
Paleoenvironmental Changes ◽  
Sandy Layer ◽  
Sediment Layers ◽  
Five Phases ◽  
First Time ◽  
Very High

Abstract. The Tunisian coast has been affected in the past by many events of extreme marine submersion (storms and tsunamis). A high-resolution study along two sediment cores taken from the lagoon of Ghar El Meleh was performed to identify the different paleoextreme events and to reconstruct the paleoenvironmental changes in the northeastern part of Tunisia during the Late Holocene. A very high-resolution sedimentological analysis (granulometric and geochemical) was applied to these cores. These cores were also dated with isotopic techniques (137Cs, 210Pbex, 14C), and the outcomes reveal five phases of paleoenvironmental changes in this lagoonal complex and identify two sediment layers that are in connection with two major historical marine submersion events. The first layer is mentioned as E1 and seems to fit with the great tsunami of 365 cal CE. This event was marked by an increase in the coarse sediment, and it is correlated for the first time with the immersed city of Neapolis in the northern Gulf of Hammamet discovered in 2017 by the same tsunamis of 365 cal CE. The other sandy layer, referred to as E2, was dated from 1690 to 1760 cal CE and is marked by one specific sedimentological layer attributed to a marine submersion event. This layer could be associated with the 1693 tsunami event in southern Italy or an increase in extreme storm events.

High-resolution radiocarbon dating to reconstruct last century environmental changes in the pacific island of Espiritu Santo

2021 ◽  
Author(s):  
Giorgia Camperio ◽  
Caroline Welte ◽  
S. Nemiah Ladd ◽  
Matthew Prebble ◽  
Nathalie Dubois
Keyword(s):  
High Resolution ◽  
Radiocarbon Dating ◽  
Environmental Changes ◽  
Accumulation Rate ◽  
Sediment Cores ◽  
Volcanic Eruptions ◽  
High Accumulation ◽  
Sedimentary Records ◽  
The Pacific ◽  
Rapid Accumulation

<p>Espiritu Santo is one of the 82 islands of the archipelago of Vanuatu and is the largest, highest, and most biodiverse of the insular country. Climatic changes linked to El Niño and extreme events such as cyclones and volcanic eruptions are a daily challenge in this remote area. These events can be recorded in sedimentary archives. Here we present a multi-proxy investigation of sediment cores retrieved from two small lakes located on the West coast of Espiritu Santo. Although the records span the last millennium, high-resolution radiocarbon dating of macrofossils reveals a rapid accumulation of sediment in the past 100 years. The high accumulation rate coupled with the high-resolution dating of freshwater sediments allows us to compare the <sup>14</sup>C bomb curve with the biogeochemical proxies of the sedimentary records. The results can then be validated against written and oral historical records linked with the societal perception of recent environmental changes in this vulnerable ecosystem.</p><div> <div title="Translate selected text"></div> <div title="Play"></div> <div title="Copy text to Clipboard"></div> </div>

A new system for acquisition and processing of very high‐resolution seismic reflection data

Geophysics ◽  
1990 ◽  
Vol 55 (8) ◽  
pp. 1036-1046 ◽  
Author(s):  
G. Lericolais ◽  
J. P. Allenou ◽  
S. Berné ◽  
P. Morvan
Keyword(s):  
High Resolution ◽  
Seismic Reflection ◽  
Seismic Reflection Data ◽  
Sand Waves ◽  
Reflection Data ◽  
Seismic Data Acquisition ◽  
Using Data ◽  
Marine Seismic ◽  
Sediment Layers ◽  
Very High

A new digital seismic data acquisition system and accompanying software have been developed by Ifremer to replace the analog equipment commonly used in very high‐resolution (less than 1 m) shallow marine seismic reflection surveys. The acquisition part, based on a Hewlett‐Packard 9000 microcomputer, is capable of sampling rates of up to 15 kHz for one channel. Signal processing and image processing can be performed either during the survey by the acquisition computer or after the survey with a software system that runs on a Sun workstation. The system has been developed for the specific requirements of coastal studies; understanding of the sediment layers in such studies requires a vertical resolution of around 1 m in the top 10 m of sediment. This system has been successfully used for the study of subtidal sand waves off the Cherbourg peninsula (France). The results, which revealed the internal structure of sand waves from about 3 m to 8 m high, correlated well with synthetic seismograms that were created using data from core studies of the survey area.

scholarly journals Extreme marine events revealed by lagoonal sedimentary records in Ghar el Melh during the last 2500 years in the northeast of Tunisia

2020 ◽  
Author(s):  
Balkis Samah Kohila ◽  
Laurent Dezileau ◽  
Soumaya Boussetta ◽  
Tarek Melki ◽  
Nejib Kallel
Keyword(s):  
High Resolution ◽  
Environmental Changes ◽  
Fine Particles ◽  
Sediment Cores ◽  
Ice Age ◽  
Second Phase ◽  
Storm Events ◽  
The North ◽  
Climatic Period ◽  
North Eastern

Abstract. The Tunisian coast has been affected in the past by many events of extreme marine submersion (storms and tsunamis). A high-resolution study along two sediment cores GEM3 and GEM4 taken from the lagoon of the Ghar el Melh was performed to identify the different paleo-extreme events and to reconstruct the paleo-environmental changes of the North-eastern part of Tunisia during the Late Holocene. A very high-resolution of analysis (sedimentological, granulometric, and geochemical) was applied on these cores. These cores were also dated with isotopic techniques (137Cs, 210Pbex, 14C) and the outcomes reveal fives phases of paleoenvironmental changes of this lagoonal complex. The first phase dated from −275 to 200 Cal AD characterized by a high percentage of Silt and Clay (fine particles) indicating a protected lagoon. The second phase synchronous with the Dark Age Climatic Period dated from 200 to 1100 Cal AD, is marked by an increase in the coarse sediment and could be explained by a weakening of the sandy barrier due to an increase of storm events. The third phase is characterized by a return to a closed lagoon during the Medieval Warm Period (from 1100 to 1690 Cal AD). The fourth phase dated from 1690 to 1760 Cal AD coincide with the Little Ice Age and is marked by one specific sedimentological layer attributed to a marine submersion event. This layer could be associated to the 1693 tsunami event in southern Italy or an increase of extreme storm events. The fifth phase covering the last 250 years present a reclosing of the lagoon.

Mapping a bloom of the coccolithophorid Emiliania huxleyi from airborne thematic mapper (ATM) data

1996 ◽  
Vol 76 (4) ◽  
pp. 839-849 ◽  
Author(s):  
Carlos Garcia-Soto ◽  
Bablu Sinha ◽  
Robin D. Pingree
Keyword(s):  
High Resolution ◽  
Close Agreement ◽  
Emiliania Huxleyi ◽  
Scale Structure ◽  
Satellite Observations ◽  
Thematic Mapper ◽  
Fine Scale ◽  
Visible Band ◽  
First Time ◽  
Very High

The fine-scale structure of a bloom of the coccolithophorid Emiliania huxleyi has been mapped for the first time with an airborne thematic mapper (ATM) scanner (visible bands at 420–450 nm, 450–520 nm, 520–600 nm, 605–625 nm and 630–690 nm). The airborne results are in close agreement with simultaneous satellite observations from the visible band (580–680 nm) of the advanced very high resolution radiometer (AVHRR

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

1994 ◽  
Vol 144 ◽  
pp. 593-596
Author(s):  
O. Bouchard ◽  
S. Koutchmy ◽  
L. November ◽  
J.-C. Vial ◽  
J. B. Zirker
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Field Of View ◽  
Small Field ◽  
High Resolution Analysis ◽  
Ccd Observations ◽  
Resolution Analysis ◽  
Very High ◽  
Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

Ground state molecular parameters of phosphine, PH3, from the simultaneous analysis of the high-resolution infrared, microwave and submillimeterwave spectra

1985 ◽  
Vol 50 (11) ◽  
pp. 2480-2492 ◽  
Author(s):  
Soňa Přádná ◽  
Dušan Papoušek ◽  
Jyrki Kauppinen ◽  
Sergei P. Belov ◽  
Andrei F. Krupnov ◽  
...  
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Ground State ◽  
Unitary Transformation ◽  
Point Of View ◽  
Acoustic Detection ◽  
Molecular Parameters ◽  
Microwave Spectrometer ◽  
Fourier Transform Spectra ◽  
First Time

Fourier transform spectra of the ν2 band of PH3 have been remeasured with 0.0045 cm-1 resolution. Ground state combination differences from these data have been fitted simultaneously with the microwave and submillimeterwave data to determine the ground state spectroscopical parameters of PH3 including the parameters of the Δk = ± 3n interactions. The correlation between the latter parameters has been discussed from the point of view of the existence of two equivalent effective rotational operators which are related by a unitary transformation. The ΔJ = 0, +1, ΔK = 0 (A1 ↔ A2, E ↔ E) rotational transitions in the ν2 and ν4 states have been measured for the first time by using a microwave spectrometer and a radiofrequency spectrometer with acoustic detection.

scholarly journals Molecules in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 415-420 ◽  
Author(s):  
R. S. Booth ◽  
Th. De Graauw
Keyword(s):  
High Resolution ◽  
Molecular Clouds ◽  
Short Review ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Giant Molecular Clouds ◽  
Interstellar Molecules ◽  
First Time ◽  
Excitation Conditions

In this short review we describe recent new observations of millimetre transitions of molecules in selected regions of the Magellanic Clouds. The observations were made using the Swedish-ESO Submillimetre Telescope, SEST, (Booth et al. 1989), the relatively high resolution of which facilitates, for the first time, observations of individual giant molecular clouds in the Magellanic Clouds. We have mapped the distribution of the emission from the two lowest rotational transitions of 12CO and 13CO and hence have derived excitation conditions for the molecule. In addition, we have observed several well-known interstellar molecules in the same regions, thus doubling the number of known molecules in the Large Magellanic Cloud (LMC). The fact that all the observations have been made under controlled conditions with the same telescope enables a reasonable intercomparison of the molecular column densities. In particular, we are able to observe the relative abundances among the different isotopically substituted species of CO.

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