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i t r y

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Four distinct glacial / interglacial cycle during the last 380 Kyr have been recognized in the Red Sea. The identified four cycles reveal deviation in deep-sea ecosystem between the northern and southern Red Sea. In the northern Red Sea salinity fluctuations, productivity and deep-water ventilation and formation had the major impact on benthic foraminiferal pattern corresponding to glacial/interglacial cycles and glacio-eustatic sea level changes coupled with the impact of Mediterranean climate regime. While in the southern Red Sea region the oscillation trend of benthic foraminiferal pattern within the glacials and interglacials stages, indicating a high frequency environmental alternation. This alternation is consistent with the extent of NE monsoonal wind that controls the intensity and extension of the productivity, which in turn determine organic matter fluxes and oxygen level at the sea floor. The benthic foraminiferal faunas from samples of two piston cores retrieved along a North–South transect in the Red Sea were studied. Benthic foraminiferal faunas from both sites exhibit large variability with respect to density, diversity, species composition and assemblages combined with stable oxygen and carbon isotope records of planktic and benthic foraminifera. One hundered thirty benthic foraminiferal species were identified in the investigated cores. The faunal data set of the northern core was reduced to five assemblages (factors) while the southern one was reduced to four assemblages. All assemblages were ranked according to their ecological significance. Besides, Relative abundance of major benthic foraminiferal suborders (Textulariina (agglutinating foraminifera), Miliolina, and Rotaliina), in addition to infaunal/epifaunal relative abundance were used as paleoenvironmental proxies allowing the reconstruction of past changes in deep-water salinity, ventilation, and organic carbon fluxes at the sea-floor.

References:Badawi, A., (2015). Late quaternary glacial/interglacial cyclicity models of the Red Sea. Environmental Earth Sciences, 73 (3): 961-977.

Badawi, A., Schmiedl, G., Hemleben, C., (2005). Impact of late Quaternary environmental changes on deep-sea benthic foraminiferal faunas of the Red Sea. Mar. Micropaleontol., 58 (1): 13–30.

Berger, A., Loutre, M.F., 1991.Insolation Values for the Climate of the Last 10 Million Years. Quaternary Science Reviews 10,297–317.

Birch, H., Coxall , H., Pearson, P., Kroon, D., O'Regan, M., 2013. Planktonic foraminifera stable isotopes and water column structure: Disentangling ecological signals. Mar. Micropaleontol. In Press:1-19

Bower, A.S., Furey, H.H., 2012. Mesoscale eddies in the Gulf of Aden and their impact on the spreading of Red Sea Outflow Water. Progress in Oceanography,96.

Edelman-Fürstenberg, Y., Almogi-Labin, A., and Hemleben, Ch., (2009). Palae-oceanographic evolution of the central Red Sea during the late Holocene. The Holocene,19 (1): 117–127.

Fleitmann, D., 2007. Holocene ITCZ and Indian monsoon dynamics recorded in stalagmites from Oman and Yemen (Socotra). Quaternary Sc. Rev., 26: 170–188.

Hemleben, Ch., Meischner, D., Zahn, R., Almogi-Labin, A., Erlenkeuser, H. and Hiller, B., 1996. Three hundred eighty thousand year long stable isotope and faunal record from the Red Sea: Influence of global sea level change on hydrography. Paleoceanography 11(2), 147-156.

Prell, W.L., Imbrie, J., Martinson, D.G., Morley, J.J., Pisias, N.G., Shackleton, N.J., Streeter, H.F., 1986. Graphic correlation of oxygen isotope stratigraphy application to the Late Quaternary Paleoceanography. American Geophysical Union 1:22, 137-162.

Siccha, M., Trommer, G., Schulz, H., Hemleben, Ch., and Kucera, M., 2009. Factors controlling the distribution of planktonic foraminifera in the Red Sea and implications for the development of transfer functions. Mar. Micropaleontol.,72: 146–156

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th (

cm b

sf)

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Gulf of Suez

Babel Mandeb

~ 47 mEvaporation

Arid & Cold

Dominant NE MonsoonMed. Winds

Gulf of Aden

~ 18 ºN

(c)

(4)

Stage 6~ 186-128 Kyr BP

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Gulf of Suez

Babel Mandeb

~ 122 m

Gulf of Aden

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Gulf of Ade

Gulf of Suez

Babel Mandeb

Dominant NE Monsoon

Cool & Arid

Evaporation ~ 82 m

Med. Winds

(a)

(1)

(2)

(3)

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Stage 8~ 303-245 Kyr BP

Dominant SW Monsoon

Humid & Warm

~ 112 m

Rain fall

~ 20-22 ºN

Gulf of Suez

Gulf of Aden

Babel Mandeb

~ 40 ‰

~ 36 ‰~ 37 ‰

(b)Stage 7~ 245-186 Kyr BP

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~ 67 m

Babel Mandeb

Dry & Cold

Evaporation

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Gulf of Aden

Stage 4~ 71-59 Kyr BP

OMZ

(e)

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~77 m

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Babel Mandeb

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Gulf of Aden

(f)Stage 3

~ 59-24 Kyr BP

OMZ

Gulf of Suez

Gulf of Aden

~17 m

Arid & Cold

Evaporation

Babel Mandeb

Med. Winds

EnhancedNE Monsoon

~ 55 ‰ ~ 49 ‰

~ 57 ‰

(g)LGM~ 24-12 Kyr BP

OMZ

~137 m

Arid Climate

Gulf of Suez

Babel Mandeb

Gulf of Aden

Evaporation

Med. Winds

Dominant NE Monsoon

~ 37 ‰

~41 ‰

~ 38 ‰

(h)Recent

Fig. 8: Schematic models of the Late Quaternary Red Sea modified after the Recent circulation pattern (h) of Cember (1988). (1) Vertical mixing, (2) deep water formation, (3) organic matter fluxes, (4) convection cell.

Fig. 3: Age model of the northern and southern Red Sea core.

Fig. 1: Map of the Red Sea and investigated core positions. GeoTüKL23 recovered during Meteor cruise M 31/2 at 702 m water depth, with a core recovery of 22.1 m, and GeoTü Kl42 during the Sonne cruise 121, at 958 m water depth, with a core recovery of 10.4 m.

AcknowledgementsDr. M. Segl is acknowledged for performing the stable isotope measurements at the Department of Geosciences, Bremen University. Appreciations are to Dr. Ch. Hemleben for his critical discussions and support. Thanks are due to the ship crews and scientists of R/V Meteor and R/V Sonne for good collaboration during cruises.

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H igh

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(b) (f)(e) (g) (h)(d)(c)(a)

Fig. 4: a) Graphical correlation of global standard isotope curve (Imbrie et al., 1984) (gray line) with stable oxygen isotope curve of planktic foraminifera G. ruber (black line) and benthic foraminifera C. mabahethi (stippled line). b) Graphical correlation of global standard isotope curve (Imbrie et al., 1984) (gray line) with oxygen isotope curve of planktic foraminifera G. ruber. c) Stable carbon isotope curve of planktic foraminifera G. ruber (black line), and benthic foraminifera C. mabahethi (stippled line). d) Stable carbon isotope curve of planktic foraminifera G. ruber . Benthic foraminiferal number (BFN) and benthic foraminiferal diversity of cores GeoTu¨ KL23 and GeoTu¨ KL42 (e, f, g and h) .

Fig. 5: Benthic foraminiferal assemblages (Principal component analysis) of the northern and southern Red Sea core GeoTü KL23 and GeoTü KL42, respectively, against age. Significat factor loadings (> 0.4).

Fig. 6: Environmental proxies in the northern and southern Red Sea core against age.

Fig. 7 : Climatic parameters influencing the Red Sea during the Late Quaternary. a) and c) Infaunal (shallow and deep) relative abundance of total fauna of GeoTü KL23 and GeoTü KL42. b) Sea level changes (Waelbroeck et al., 2002), stipped line represent recent sea level (137 m) . d) Summer insolation values at 65ºN (Berger and Loutre, 1991).

SW MonsoonOrganic Matter

Red Sea

Late Quaternary Glacial / Interglacial Cyclicity Models of the Red Sea 

Amani BadawiNational Institute of Oceanography and Fisheries, Alexandria, Egypt amani_badawi@yahoo.com

National Institute of Oceanography and FisheriesVienna | Austria | 12 – 17 April 2015

Deep-sea ecosystem variability of the Red Sea is strongly linked with global sea level history and regional climate changes during the past four glacial–interglacial cycles. Productivity and related organic matter fluxes are controlled by regional climate and oceanographic processes. In the northern Red Sea, surface water mixing and fertilization of the northern Red Sea is influenced by the Mediterranean climate. Stronger winds, enhanced dust flux and hence surface water productivity are reconstructed for glacial periods and more oligotrophic conditions for interglacial periods as reflected by the proportion of infaunal taxa and the benthic foraminiferal number. Trophic conditions of the Southern Red Sea are related to the inflow of nutrient-rich surface water masses from the Gulf of Aden (GASW) driven by SSE winds during the winter season. Increase of GASW inflow was likely enhanced during glacials due to a generally stronger NE winter monsoon and a more negative water budget (higher evaporation rates) of the Red Sea under glacial boundary conditions. At minimum sea level, however, GASW inflow may have been at a minimum due to the shallow and narrow strait at Bab el Mandeb. Enhanced glacial organic matter fluxes in the northern and southern Red Sea associated with increased oxygen consumption in the water column, consequently, vertical expansion of the OMZ. Deep water formation of the Red Sea seems to have been primarily influenced by changes in surface water salinity and basin morphology that in turn are controlled by global sea level. Vertical mixing and deep water formation should have been generally enhanced during glacials with additional deep water formation sites in the southern Red Sea. However, emerged shelf areas of the Gulf of Suez during times of lowest sea level, in particular during late MIS 6 and MIS 2, likely resulted in a drop of formation of dense deep waters in the northern Red Sea. At least some deep water formation persisted throughout glacial intervals, presumably originating from the Gulf of Aqaba, resulted in hypersaline glacial deep waters with salinity values comparable to those of surface waters.

3

1

Glacial/interglacial

Mediterranean climate

Monsoonal changes

Deep-water formation

Salinity fluctuations

Trophic magnitude

Oxygen level

Controlled By

Forced by

Eccentricity Precession

Deep Sea Variability

Southern Red Sea

Northern Red Sea

Influenced By