Synoptic conditions of fine-particle transport to the last interglacial Red Sea-Dead Sea from Nd-Sr compositions of sediment cores

2018 ◽  
Vol 179 ◽  
pp. 123-136 ◽  
Author(s):  
Daniel Palchan ◽  
Mordechai Stein ◽  
Steven L. Goldstein ◽  
Ahuva Almogi-Labin ◽  
Ofir Tirosh ◽  
...  
Keyword(s):  
Red Sea ◽  
Particle Transport ◽  
Fine Particle ◽  
Sediment Cores ◽  
Dead Sea ◽  
Last Interglacial ◽  
Synoptic Conditions

scholarly journals Disruption of the Atlantic Meridional Circulation during Deglacial Climates Inferred from Planktonic Foraminiferal Shell Weights

2021 ◽  
Vol 9 (5) ◽  
pp. 519
Author(s):  
Stergios D. Zarkogiannis
Keyword(s):  
Atlantic Ocean ◽  
Meridional Circulation ◽  
Order Approximation ◽  
Planktonic Foraminifera ◽  
Sediment Cores ◽  
Meridional Overturning Circulation ◽  
Density Structure ◽  
Last Interglacial ◽  
Shell Weight ◽  
The North

Changes in the density structure of the upper oceanic water masses are an important forcing of changes in the Atlantic Meridional Overturning Circulation (AMOC), which is believed to widely affect Earth’s climate. However, very little is known about past changes in the density structure of the Atlantic Ocean, despite being extensively studied. The physical controls on planktonic foraminifera calcification are explored here, to obtain a first-order approximation of the horizontal density gradient in the eastern Atlantic during the last 200,000 years. Published records of Globigerina bulloides shells from the North and Tropical eastern Atlantic were complemented by the analysis of a South Atlantic core. The masses of the same species shells from three different dissolution assessed sediment cores along the eastern Atlantic Ocean were converted to seawater density values using a calibration equation. Foraminifera, as planktonic organisms, are subject to the physical properties of the seawater and thus their shells are sensitive to buoyancy forcing through surface temperature and salinity perturbations. By using planktonic foraminifera shell weight as an upper ocean density proxy, two intervals of convergence of the shell masses are identified during cold intervals of the last two deglaciations that may be interpreted as weak ocean density gradients, indicating nearly or completely eliminated meridional circulation, while interhemispheric Atlantic density differences appear to alleviate with the onset of the last interglacial. The results confirm the significance of variations in the density of Atlantic surface waters for meridional circulation changes.

Radiocarbon dating of individual foram tests show that alleged Lessepsian species are of Holocene age

2021 ◽  
Author(s):  
Paolo G. Albano ◽  
Anna Sabbatini ◽  
Jonathan Lattanzio ◽  
Jan Steger ◽  
Sönke Szidat ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Red Sea ◽  
Native Species ◽  
Radiocarbon Dating ◽  
Suez Canal ◽  
Tropical Species ◽  
Indigenous Species ◽  
Last Interglacial ◽  
Sediment Depth ◽  
The Mediterranean

<p>The Lessepsian invasion – the largest marine biological invasion – followed the opening of the Suez Canal in 1869 (81 years BP). Shortly afterwards, tropical species also distributed in the Red Sea appeared on Mediterranean shores: it was the dawn of what would become the invasion of several hundred tropical species. The time of the Suez Canal opening coincided with an acceleration in natural history exploration and description, but the eastern sectors of the Mediterranean Sea lagged behind and were thoroughly explored only in the second half of the 20<sup>th</sup> century. Many parts are still insufficiently studied today. Baseline information on pre-Lessepsian ecosystem states is thus scarce. This knowledge gap has rarely been considered by invasion scientists: every new finding of species belonging to tropical clades has been assumed to be a Lessepsian invader.</p><p>We here question this assumption by radiocarbon dating seven individual tests of miliolids – imperforated calcareous foraminifera – belonging to five alleged non-indigenous species. Tests were found in two sediment cores collected at 30 and 40 m depth off Ashqelon, on the Mediterranean Israeli shelf. We dated one <em>Cribromiliolinella milletti </em>(core at 40 m, 20 cm sediment depth), three <em>Nodophthalmidium antillarum </em>(core at 40 m, 35 cm sediment depth), one <em>Miliolinella </em>cf. <em>fichteliana </em>(core at 30 m, 110 cm sediment depth), one <em>Articulina alticostata </em>(core at 40 m, 35 cm sediment depth) and one <em>Spiroloculina antillarum </em>(core at 30 m, 110 cm sediment depth). All foraminiferal tests proved to be of Holocene age, with a median calibrated age spanning between 749 and 8285 years BP. Only one test of <em>N. antillarum</em> showed a 2-sigma error overlapping the time of the opening of the Suez Canal, but with a median age of 1123 years BP. Additionally, a thorough literature search resulted in a further record of <em>S. antillarum</em> in a core interval dated 1820–2064 years BP in Turkey.</p><p>Therefore, these foraminiferal species are not introduced, but native species. They are all circumtropical or Indo-Pacific and in the Mediterranean distributed mostly in the eastern sectors (only <em>S. antillarum</em> occurs also in the Adriatic Sea). Two hypotheses can explain our results: these species are Tethyan relicts that survived the Messinian salinity crisis (5.97–5.33 Ma) and the glacial periods of the Pleistocene in the Eastern Mediterranean, which may have never desiccated completely during the Messinian crisis and which may have worked as a warm-water refugium in the Pleistocene; or they entered the Mediterranean Sea from the Red Sea more recently but before the opening of the Suez Canal, for example during the Last Interglacial (MIS5e) high-stand (125,000 years BP) when the flooded Isthmus of Suez enabled exchanges between the Mediterranean and the Indo-Pacific fauna. The recognition that some alleged Lessepsian invaders are in fact native species influences our understanding of the invasion process, its rates and environmental correlates.</p>

scholarly journals Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial

2011 ◽  
Vol 7 (2) ◽  
pp. 1195-1233 ◽  
Author(s):  
G. Trommer ◽  
M. Siccha ◽  
E. J. Rohling ◽  
K. Grant ◽  
M. T. J. van der Meer ◽  
...  
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Planktonic Foraminifera ◽  
Gulf Of Aden ◽  
Last Interglacial ◽  
The Holocene ◽  
Circulation Mode ◽  
Monsoon Strength ◽  
Mis 5E ◽  
Mis 5

Abstract. This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by micropaleontological and geochemical proxies. The recovery of the planktonic foraminiferal fauna following high salinities during MIS 6 took place at similar sea-level stand (~50 m below present day), and with a similar species succession, as during termination I. This indicates a consistent sensitivity of the basin oceanography and the plankton ecology to sea-level forcing. Based on planktonic foraminifera, we find that increased water exchange with the Gulf of Aden especially occurred during the sea-level highstand of interglacial MIS 5e. From MIS 6 to the peak of MIS 5e, northern Red Sea SST increased from 21 °C to 25 °C, with about 3 °C of this increase taking place during termination II. Changes in planktonic foraminiferal assemblages indicate that the development of the Red Sea oceanography during MIS 5 was strongly determined by insolation and monsoon strength. The SW Monsoon summer circulation mode was enhanced during the termination, causing low productivity in northern central Red Sea core KL9, marked by high abundance of G. sacculifer, which – as in the Holocene – followed summer insolation. Core KL11 records the northern tip of the intruding intermediate water layer from the Gulf of Aden and its planktonic foraminifera fauna shows evidence for elevated productivity during the sea-level highstand in the southern central Red Sea. By the time of MIS 5 sea-level regression, elevated organic biomarker BIT values suggest denudation of soil organic matter into the Red Sea and high abundances of G. glutinata, and high reconstructed chlorophyll-a values, indicate an intensified NE Monsoon winter circulation mode. Our results imply that the amplitude of insolation fluctuations, and the resulting monsoon strength, strongly influence the Red Sea oceanography during sea-level highstands by regulating the intensity of water exchange with the Gulf of Aden. These processes are responsible for the observation that MIS 5e/d is characterized by higher primary productivity than the Holocene.

scholarly journals Exponential increase of plastic burial in mangrove sediments as a major plastic sink

2020 ◽  
Vol 6 (44) ◽  
pp. eaaz5593 ◽  
Author(s):  
C. Martin ◽  
F. Baalkhuyur ◽  
L. Valluzzi ◽  
V. Saderne ◽  
M. Cusack ◽  
...  
Keyword(s):  
Red Sea ◽  
Surface Waters ◽  
Sediment Cores ◽  
Arabian Gulf ◽  
Avicennia Marina ◽  
Plastic Pollution ◽  
Mangrove Sediments ◽  
Burial Rate ◽  
Exponential Increase ◽  
Accretion Rates

Sequestration of plastics in sediments is considered the ultimate sink of marine plastic pollution that would justify unexpectedly low loads found in surface waters. Here, we demonstrate that mangroves, generally supporting high sediment accretion rates, efficiently sequester plastics in their sediments. To this end, we extracted microplastics from dated sediment cores of the Red Sea and Arabian Gulf mangrove (Avicennia marina) forests along the Saudi Arabian coast. We found that microplastics <0.5 mm dominated in mangrove sediments, helping explain their scarcity, in surface waters. We estimate that 50 ± 30 and 110 ± 80 metric tons of plastic may have been buried since the 1930s in mangrove sediments across the Red Sea and the Arabian Gulf, respectively. We observed an exponential increase in the plastic burial rate (8.5 ± 1.2% year−1) since the 1950s in line with the global plastic production increase, confirming mangrove sediments as long-term sinks for plastics.

scholarly journals Seismic structure beneath the Gulf of Aqaba and adjacent areas based on the tomographic inversion of regional earthquake data

Solid Earth ◽  
2016 ◽  
Vol 7 (3) ◽  
pp. 965-978 ◽  
Author(s):  
Sami El Khrepy ◽  
Ivan Koulakov ◽  
Nassir Al-Arifi ◽  
Alexey G. Petrunin
Keyword(s):  
Travel Time ◽  
Red Sea ◽  
Lateral Displacement ◽  
Dead Sea ◽  
Gulf Of Aqaba ◽  
Seismic Structure ◽  
Time Data ◽  
Tomographic Inversion ◽  
Velocity Anomaly ◽  
Surrounding Areas

Abstract. We present the first 3-D model of seismic P and S velocities in the crust and uppermost mantle beneath the Gulf of Aqaba and surrounding areas based on the results of passive travel time tomography. The tomographic inversion was performed based on travel time data from ∼ 9000 regional earthquakes provided by the Egyptian National Seismological Network (ENSN), and this was complemented with data from the International Seismological Centre (ISC). The resulting P and S velocity patterns were generally consistent with each other at all depths. Beneath the northern part of the Red Sea, we observed a strong high-velocity anomaly with abrupt limits that coincide with the coastal lines. This finding may indicate the oceanic nature of the crust in the Red Sea, and it does not support the concept of gradual stretching of the continental crust. According to our results, in the middle and lower crust, the seismic anomalies beneath the Gulf of Aqaba seem to delineate a sinistral shift (∼ 100 km) in the opposite flanks of the fault zone, which is consistent with other estimates of the left-lateral displacement in the southern part of the Dead Sea Transform fault. However, no displacement structures were visible in the uppermost lithospheric mantle.

scholarly journals Seismic structure beneath the Gulf of Aqaba and adjacent areas based on the tomographic inversion of regional earthquake data

2016 ◽  
Author(s):  
Sami El Khrepy ◽  
Ivan Koulakov ◽  
Nassir Al-Arifi ◽  
Alexey Petrunin
Keyword(s):  
Travel Time ◽  
Red Sea ◽  
Lateral Displacement ◽  
Relative Displacement ◽  
Dead Sea ◽  
Gulf Of Aqaba ◽  
Seismic Structure ◽  
Time Data ◽  
Tomographic Inversion ◽  
Seismic Anomalies

Abstract. The Gulf of Aqaba is an elongated basin (~180 x 20 km) with depths reaching 1850 m. It represents the southern segment of the Dead Sea Transform (DST), which is one of the largest transform fault zones in the world. The opening of Gulf of Aqaba is thought to have originated from the relative displacement of the African and Arabian Plates. According to historical and recent earthquake records, it is seismically active. In this study, we present the first 3D model of seismic P and S velocities beneath the Gulf of Aqaba area based on the results of passive travel time tomography. The tomographic inversion was performed based on travel time data from ~9000 regional earthquakes provided by the Egyptian National Seismological Network (ENSN) and the International Seismological Center (ISC). The inversion results are generally consistent for P- and S-velocity patterns at all depths. At all depth intervals in the Red Sea, we observed strong high-velocity anomalies with abrupt limits that coincide with the coastal lines. This finding suggests that the oceanic nature of the crust in the northern Red Sea does not support the concept of gradual stretching of the continental crust. According to our results, in the middle and lower crust, the seismic anomalies seem to delineate a sinistral shift (~100 km) in the opposite flanks of the fault zone that is consistent with other estimates of the left-lateral displacement in the southern part of the DST. However, no displacement structures are visible in the upper-most lithospheric mantle.

Israeli-Jordanian water deal leaves Palestinians dry

2015 ◽  
Keyword(s):  
World Bank ◽  
Red Sea ◽  
Water Exchange ◽  
Dead Sea ◽  
Palestinian Authority ◽  
Content Type ◽  
Water Sharing ◽  
The North ◽  
The Dead ◽  
Local Water

Subject The implications of the Red Sea-Dead Sea plan. Significance Israel and Jordan on February 26 signed an agreement to facilitate water-sharing and address the depletion of the Dead Sea, which is receding at a rate of about a metre per year. The 900 million dollar World Bank-sponsored 'Seas Canal' deal consists of two main aspects: local water exchange deals, with Jordan providing Israel with desalinated water from Aqaba in exchange for bluewater from the Sea of Galilee in the north; and saltwater transfer from the Red Sea to the Dead Sea. The Palestinian Authority is not party to the agreement, and awaits a separate deal with Israel. Impacts Prospects for Palestinian-Israeli water negotiations have drastically decreased. Jordan will still need to agree further desalination and cooperation deals in order to meet demand. Water saving efforts will be pushed aside in favour of much more costly desalination. Desalination powered by burning fossil hydrocarbons accelerates global warming.

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