Modern and late Quaternary clay mineral distribution in the area of the SE Mediterranean Sea

Abstract

The present-day clay mineral distribution in the southeastern Levantine Sea and its borderlands reveals a complex pattern of different sources and distribution paths. Smectite dominates the suspended load of the Nile River and of rivers in the Near East. Illite sources are dust-bearing winds from the Sahara and southwestern Europe. Kaolinite is prevalent in rivers of the Sinai, in Egyptian wadis, and in Saharan dust. A high-resolution sediment core from the southeastern Levantine Sea spanning the last 27 ka shows that all these sources contributed during the late Quaternary and that the Nile River played a very important role in the supply of clay. Nile influence was reduced during the glacial period but was higher during the African Humid Period. In contrast to the sharp beginning and end of the African Humid Period recorded in West African records (15 and 5.5 ka), our data show a more transitional pattern and slightly lower Nile River discharge rates not starting until 4 ka. The similarity of the smectite concentrations with fluctuations in sea-surface temperatures of the tropical western Indian Ocean indicates a close relationship between the Indian Ocean climate system and the discharge of the Nile River.

Origin of the Sinai–Negev erg, Egypt and Israel: mineralogical and geochemical evidence for the importance of the Nile and sea level history

“…Saharan dust that reaches the eastern Mediterranean Sea is rich in illite and contains much less smectite, a trend that has been observed for glacial periods over much of the Quaternary (Zhao et al, 2012). A core (SL 112) off Israel studied by Hamann et al (2008Hamann et al ( , 2009 shows abundant illite during the LGM and particle size modes of w40 mm, interpreted to be dominantly aeolian. With the advent of the African Humid Period at w15 ka, the most important sediment input to the eastern Mediterranean Sea became the Nile, with greatly reduced aeolian inputs.…”

“…The increase of fine-grained particles as the dominant sediment carried by the Nile during the African Humid Period is recorded in sediments of the eastern Mediterranean, off the coast of Israel, studied by Hamann et al (2008Hamann et al ( , 2009. During the Last Glacial period, the main fine-grained sediment input to the eastern Mediterranean Sea was dust from the Sahara, based on both particle size and clay mineralogical data.…”

“…Indeed, Williams (2012) notes that during the Pleistocene, dunes migrated across a dry White Nile river bed. Butzer and Gladfelter (1968) studied Pleistocene fluvial sediments Bard et al, 1990;Toscano and Lundberg, 1998;Toscano and Macintyre, 2003;Peltier and Fairbanks, 2006); (C) particle size data, expressed as fractions of 1 for fluvial (EM3) sediment and (D) clay mineralogy in eastern Mediterranean Sea core SL 112 and inferred dominant sediment sources (data from Hamann et al (2008Hamann et al ( , 2009); and (E) periods of dune activity in the Negev Desert of Israel, based on OSL ages (Roskin et al, 2011b). of the Nile along numerous reaches in the Sahara, including segments that are now flooded because of the construction of the Aswan High Dam. They document very high quartz contents in Nile sands and infer that Nubian Sandstone is the source of this mineral.…”

“…Increased moisture at the beginning of the Holocene could have been supplied by insolation-forced northward migration of the intertropical convergence zone, or ITCZ (Bernhardt et al, 2012). This has been referred to as the African Humid Period (w15 kae5.5 ka) and is well established as a period of diminished dust accumulation in the early-to mid-Holocene, based on studies of marine cores off Africa in both the Atlantic (DeMenocal et al, 2000) and the Mediterranean (Hamann et al, 2008(Hamann et al, , 2009). During such a humid period, sand supplies to dunes in some parts of the region may have been cut off by the growth of Holocene lakes in basins that previously provided sediment (ultimately from fluvial sources) to active dunes (Lancaster, 2008).…”

A distal 140 kyr sediment record of Nile discharge and East African monsoon variability

“…Most of the silt-and sandsized sediment accumulates in the Nile Delta, on the Nile cone, and along the Mediterranean shelf, whereas the claysized sediment fraction is transported in suspension by the surface currents of the Mediterranean Sea to the east and north ( Fig. 1; Venkatarathnam and Ryan, 1971;Foucault and Mélières, 2000;Hamann et al, 2009).…”