GeolCarp_Vol58_No4_383

GEOLOGICA CARPATHICA, AUGUST 2007, 58, 4, 383—395

www.geologicacarpathica.sk

Clay mineral distribution patterns in the southeastern

Mediterranean Sea during the late Quaternary

GEORGE ANASTASAKIS

Faculty of Geology and Geoenvironment, University of Athens, Panepistimiopolis, 15784 Athens, Greece; anastasakis@geol.uoa.gr

(Manuscript received May 5, 2006; accepted in revised form December 7, 2006)

Abstract: The clay mineral distribution patterns in three stratigraphically well-defined piston cores containing the
uppermost five sapropel sequences (70,000 years BP to the present) in the southeastern Mediterranean Sea have been
studied. The temporal variations and spatial distribution of the sum of smectite plus kaolinite, the dominant clay
minerals of the Nile River, can be closely related to enhanced suspended sediment transport by the Nile that occurred
mostly during the transition phases from an arid to a moist paleoclimatic episode. The most pronounced input of
Nilotic provenance clay occurs within and between the sapropel layers S-5 and S-4. Between circa 70,000 and 45,000
years BP this time interval marks the transition phase from the cold-arid early Würmian period to the very wet middle
Würmian phase that affected the Nile drainage system and probably caused the activation of numerous wadi systems.
The other most intense similar phase occurred after 12,500 years BP as manifested by the concomitant increase of
hemipelagic sedimentation, due to the extensive Nile flooding and the resulting dramatic increase in suspensite
delivery, leading to a pronounced increase of the Nile clay assemblages within the S-1. Major sea-level fluctuations,
such as the regression at 18,000 years BP, had a pronounced effect on clay mineralogy leading to a marked increase
in the deposition of illite micas plus mixed layered clays reflecting intensification of shelf erosion.

Key words: environmental provenance, late Quaternary lithostratigraphy, Eastern Mediterranean cores, XRD, clay
mineral assemblages, Nile clays.

Introduction

Upper Quaternary paleoclimatological interpretation of ar-
eas bordering the eastern Mediterranean is derived mostly
from the floral and faunal composition of non-marine sedi-
ments excavated at various archaeological sites. Addition-
al data are stratigraphically related to peat bogs, lake
sediments, littoral and fluvial terraces and loess deposits.
Interpretations of these paleoclimatic markers must take
into account many other factors and processes, such as hy-
drodynamic processes of sediment movement, modifica-
tion of the watershed vegetation cover or stream gradient
changes (base level) due to sea-level fluctuations which
are rather difficult to interpret (McCoy 1980). However
terrestrial data have been proven more accurate for inter-
preting shorter period fluctuations, while deep sea sedi-
ments have provided evidence for longer period
fluctuations. Paleoclimatic interpretation from deep sea
sediments is primarily based on the content and differenti-
ation of biogenic components and their oxygen isotope
record (e.g. Shackleton & Opdyke 1973; Vergnaud-
Grazzini et al. 1977; Imbrie et al. 1984) and to a lesser de-
gree on terrigenous compositional attributes (Diester-Haas
& Chamley 1980).

Studies of regional clay mineral distribution in the

world oceans show a general correlation between climate
and mineral assemblages (Biscaye l965; Griffin et al.
1968; Rateev et al. 1968). The clay mineral associations
in the late Quaternary sediments of the Mediterranean Sea
lack indications of significant secondary alteration in the

marine environment (Emelyanov l972; Monaco 1981) a
fact in accordance with observations of older Mediterra-
nean Upper Cenozoic sediments (Chamley & Robert
1982; Chamley 1983; Chamley et al. 1986). Clay mineral-
ogy studies of late Quaternary sediments in the southeast-
ern Mediterranean have identified the significant and
locally dominant influence of the Nile River as a major
contributor of sediment to the region (Venkataratham &
Ryan 1971; Chamley 1972; Emelyanov 1972; Nir &
Nathan 1972; Maldonado & Stanley 1981). The smectite
rich Nile derived assemblages are supplemented by wind
blown kaolinite-rich dust from the North African and Mid-
dle East deserts (Yaalon & Canor 1973, 1979). Moreover,
present day desert terrains around the Nile River and the
Lake Nasser reservoir provide significant amounts of wind
transported kaolinite (Stanley & Wingerath 1996). Chester
et al. (1977), sampled dust over the East Mediterranean
Sea and found that the most significant clay mineral dust
assemblages are illite and kaolinite the latter being en-
hanced towards the Nile Cone.

The Nile River flows 6700 km from the glaciated high-

lands and montane forests of Uganda (4ºS) through the
desert plains of Sudan and Egypt, through its delta on the
Egyptian coast and into the eastern Mediterranean Sea.
The Nile drains an area of about three million km

(Fig. 1)

or about one tenth of the African continent. The main Nile
north of 8ºN latitude comprises flow from three major trib-
utaries: the White Nile, Blue Nile and Atbara River
(Fig. 2). Each rivers sediment load is derived from marked-
ly different geological terrains and climatic zones. The

385

CLAY MINERAL DISTRIBUTION PATTERNS IN THE SOUTHEASTERN MEDITERRANEAN SEA

More detailed work in the periphery of the Nile Delta

(Abu-Zeid & Stanley 1990) demonstrated that the older
soft brown muds have higher amounts of smectite and
lower of kaolinite and illite compared to the soft grey Ho-
locene sediments. Additionally, higher proportions of
smectite and lower proportions of kaolinite and illite char-
acterized the northeastern region comparatively to the
north-central delta region during both the Late Pleis-
tocene and the Recent. The north-central sector differs
from the northeastern Nile Delta in that it comprises rela-
tively higher proportions of kaolinite and lower propor-
tions of smectite (Abdel Wahab & Stanley 1991).
Investigations on the coastal plain from the Nile Delta to
the southern Lebanon borders with Israel revealed impor-
tant proportions of kaolinite in the clay fraction of sam-
ples recovered from coastal cliff exposures (Stanley et al.
1997). Kaolinite and illite at offshore sites are supplied in
part from erosion of coastal cliff sections, river input be-
tween Wadi El Arish in Sinai and the Lebanon-Israel bor-
der and from wind-borne dust from African and Middle
East deserts released seaward of the coast (Stanley et al.
1998). The present study demonstrates that the clay miner-
als from cores retrieved in the outer periphery of the Nile
Cone, in sectors not apparently affected by redepositional
processes, display significant vertical clay mineral varia-
tions. Such variations mostly record pronounced upper
Quaternary fluctuations of supply of clays by the Nile
drainage system. The results and interpretations of this
study, further prove the value and potential that clay-min-
eral assemblages may hold for paleoclimatic and prove-
nance studies of Quaternary deposits in the region
(Dominik & Stoffers 1979; Maldonado & Stanley 1981).

Materials and analytical procedure

Three piston cores (Fig. 3) were selected among several

dozens of cores available in the southeast Levantine Sea.
These cores were retrieved from the outer periphery of the
Nile Cone. Careful examinations of their X-ray radio-
graphs revealed that they contained no or minimal propor-
tions of gravity emplaced and/or reworked layers. The less
than 2 m fraction of 54 samples was obtained by decan-
tation using Stokes Law to calculate settling times. The
samples were treated with 10% H

(pH = 4.3) to remove

organic material and then washed three times using a cen-
trifuge (5000 rpm for 15 minutes). The carbonates were re-
moved with a mixture of dissodium dihydrogen EDTA
(pH4.5) and 10 % tetrasodium EDTA (pH = 9.9) which gave
an EDTA of pH = 7.7, almost equal to the pH of the sam-
ples. Oriented aggregates (OA) were prepared according to
Anastasakis (1987) method. Briefly this method involves:
a – control of the amount of clay mineral being deposited
onto the glass slide, thus obtaining clay films of optimum
thickness (3.9—7.7 m); b – rapid evaporation at tempera-
tures below 40 ºC of the clay suspension in order to avoid
size segregation.

The mineralogy was determined with a Philips Norelco

X-ray diffractometer with a focusing monochromator, an au-
tomatic divergence slit and CuK radiation at 40 kV and
30 mA. Paper speed, scale and time factors were chosen to
produce optimum results. Each glass slide was X-rayed un-
der the following conditions:

– 2º to 30º air dried and glycolated (Fig. 4);
– 2º to 14º heated to 400 ºC, heated to 500 ºC, K

satu-

rated, Mg

saturated, K

glycolated, Mg

glycerolated,

Fig. 3. Chart of the southeastern Mediterranean Sea showing general bathymetry plus major physi-
ographic features (depth in meters). The location of cores studied in this study are shown by a sol-
id dots. The core shown by a solid square is a core studied by Dominik & Stoffers (1979) and
used also, for comparison in Fig. 7.

saturated and heated to

95 ºC for several hours.

Semiquantitative estimates

of the amount of clay miner-
als present were performed
according to methods de-
scribed by Biscaye (1965).
The peak areas were measured
by a Hewlett-Packard 9820
calculator using an X-ray
plotter, digitized and stored

in a cassette memory. Where
clay minerals like vermiculite
and illite/smectite and smec-
tite/chlorite mixed layers (or
interstratifications) occurred a
modification of the original
method of Biscaye (1965)
technique was applied which
improved semiquantification

by considering that the calcu-
lated peak areas represent
100 % of the sample. Identifi-
cation of these mineral as-
semblages was based on
techniques published in vari-
ous specialized textbooks

386

ANASTASAKIS

(Carroll 1970; Brindley & Brown 1980; Moore & Rey-
nolds 1989).

Lithostratigraphy of the studied cores

The Quaternary sediments of the Nile Cone like those of

the East Mediterranean, are formed by regionally extensive
repetitive successions corresponding to cyclothems (Mal-
donado & Stanley 1976) which are centered on organic rich
sequences, the sapropels. These sapropels may be correlated
from core to core over a wide area, indicating that wide-
spread paleo-environmental conditions have affected the
entire eastern Mediterranean Sea. Numerous radiocarbon
dates and detailed sedimentological analyses by Stanley &
Maldonado (1977) have established lithostratigraphic
units that comprise the three uppermost late Quaternary cy-
cles in the Levantine Sea.

Recently accelerator mass spectrometry radiocarbon

data (AMS C14 dates) became available (Troelstra et al.
1991; Mercone et al. 2001) but was focused on the upper-
most sapropel S-1. In earlier studies the organic-rich layers
in the eastern Mediterranean were subdivided into two
groups, namely sapropels – with more than 2.0 % organic
carbon, and sapropelic – with organic carbon ranging
from 0.5 to 2.0 % (Kidd et al. 1978). The 0.5 and 2.0 %
values, while arbitrary, proved to be useful boundary
markers separating open-marine organic-poor from organ-
ic rich layers. A definition of lithofacies types forming a
sapropel sequence sensu stricto comprises the following
members, from base to top (Anastasakis & Stanley 1986):
a greyish-greenish yellow mud overlain by a yellow-grey
organic ooze which becomes darker upward and separated
from the overlying light olive-grey sapropelic or olive-
grey sapropel lithofacies by a generally pronounced sharp
contact. The latter is topped by a thin, light greenish-grey
ooze and a pale yellowish-orange to moderate brown oxi-
dized layer. The basal greyish-greenish yellow mud and
upper oxidized end members are interbedded between
lighter coloured, better oxygenated sediments below and
above the sequence.

The lithofacies associations forming the idealized com-

plete sequence are essentially of suspension-settling ori-
gin and can be distinguished on the basis of their physical
and biogenic structures, textures and composition includ-
ing organic content.

Fig. 4. Diffractograms show two examples of the clay mineral as-
semblages defined in the text. The two samples shown are from core
TR-172—19 and display typical X-ray patterns, under three different
conditions (Untreated, Glycol saturated and Heated to 500

ºC) of the

finer than 2 m fraction within (a upper sample) and above (b lower
sample) the sapropel S-1. Major peaks (Sm – smectite; K + Chl – ka-
olinite and chlorite; I – illite) are marked on the Glycol saturated
sample and d-spacing values (

Å) are shown.

Table 1: Summary of C14 dates for the studied cores.

387

CLAY MINERAL DISTRIBUTION PATTERNS IN THE SOUTHEASTERN MEDITERRANEAN SEA

Within the uppermost three Quaternary cyclothems, in

the Nile Cone, the assigned ages (Maldonado & Stanley
1976) in years before present to the top of the extensive
stratigraphic horizons, the sapropels, are: for the S-1
7000 yr BP; S-2 23,000 yr BP; S-3 38,000 yr BP. Our more
recently obtained radiocarbon dates on the cores dis-
cussed here (Table 1) suggest that the top of the sapropel
S-3 would be younger, dated at about 31,000 yr BP; and
also the top of sapropel S-4 would be dated at around
45,000 yr BP; (Fig. 5).

Clay mineral provenance in the southeast

Levantine Sea

The most significant clay mineral contribution in the

southeastern Levantine Sea (Fig. 8) is the injection of
smectite-rich Nile River sediment into the counter-clock-
wise eastern Mediterranean water mass gyre (Venkatar-
atham & Ryan 1971). High concentrations of smectite off
Lebanon reflect the transport of suspended sediments de-
rived from the Nile Delta by surface waters (Emelyanov &
Shimkus 1972). More detailed regional studies (Nir &
Nathan 1972; Chester et al. 1977; Maldonado & Stanley
1981; Nir 1984; Abu-Zeid & Stanley 1990; Abdel Wahab
& Stanley 1991; Stanley & Wingerath 1996; Stanley et al.
1998) suggest that besides smectite, kaolinite is also trans-
ported to the sea by the Nile. However there is unambigu-
ous evidence that airborne dust has a significant impact
all over the East Mediterranean and originates mostly
from African terrains such as the region of the Tibesti
Mountains in southern Libya—northern Chad and Niger,
eastern Libyan Desert (El Katara Depression) as well as
Sudan and the Ethiopian Highlands (Yaalon & Ganor
1973, 1979; Ganor 1991; Ganor et al. 1991; Prospero

Fig. 5. Generalized Levantine Sea—Nile Cone sapropel stratigraphy
displayed by the studied cores. This stratigraphy, used for regional
correlation, is based on extensive petrologic and radiocarbon
analysis, especially dense around late Quaternary organic rich
sapropel horizons. The solid bars along side of the simplified core
log indicate the sample position of the youngest radiocarbon date
obtained by us, in the southeastern Levantine Sea.

1996; Chester et al. 1996). Ganor & Foner (1996) have
quantified the mineralogical properties of Saharan dust
over Israel noting average smectite (40—80 %), kaolinite
(15—55 %) and illite (10—30 %). Kubilay et al. (1997) have
systematically sampled airborne dust on a station located
in southeastern Turkey and reported the prevelance of
smectite-palygorskite plus the persistence of subordinate
kaolinite of Saharan-Arabian provenance. The above re-
sults generally comply with earlier dust results in the sea
region between the Nile Cone and Cyprus (Chester et al.
1977). These authors distinguished a “northeastern Medi-
terranean assemblage” that is illite dominated and a major
“southeastern assemblage” that is kaolinite dominated.
Even present day clay sedimentation in the Nile Aswan
technical lake is significantly affected by wind sweeping
adjacent desert terrains (Entz 1976) incorporating a fine
silt and clay composed largely of kaolinite (Stanley &
Wingerath 1996). Other local land derived assemblages
(Fig. 7) consist predominantly of: smectite (35—70 %), il-
lite (25—45 %), chlorite (7—25 %) for Cyprus rivers (Ches-
ter et al. 1977; Shaw 1978); illite (35—65 %), smectite
(35—65 %) for the Cilician Basin (north of Cyprus) and
Seyhan Delta (southeastern Turkey, Shaw 1978), (Fig. 8).
Samples collected on the Gaza and Israeli shelf prior to
Aswan record average percentages: 49 % smectite, 33 %
kaolinite, 14 % illite and 4 % chlorite (Stanley et al.
1998). These values are similar to the Nile shelf. Stanley et
al. (1997) have shown that after the construction of the
Aswan Dam proximal clay mineral assemblages derived
from local sources (Sinai, Israel and Lebanon) are supplied
in enhanced proportions to the SE Levant margin.

Clay mineral associations

Clay mineral abundances

Core CHN-119—6 was retrieved from the Mediterranean

Ridge west of the Herodotus Abyssal Plain (Fig. 3) at a wa-
ter-depth of 2372 m. Illite is the most abundant clay min-
eral, ranging from 37 % to 57 %. Smectite is quantitatively
the second clay mineral ranging from 24 to 42 %. Kaolin-
ite varies from 15 to 28 % and its occurrence generally in-
creases in the deeper part of the core. Chlorite is the least
abundant clay mineral (less than 15 %). Traces of vermicu-
lite and random mixed layers of the illite-smectite and
chlorite-smectite type are locally present.

Core TR-172—19 is located on the northern flank of the

Mediterranean Ridge north of the termination of the Hero-
dotus Plain (Fig. 3) and west of Cyprus, at a water depth of
2354 m. Smectite is the dominant clay mineral (Fig. 4) and
ranges from 23 to 56 %. Illite is present in lesser amounts,
and ranges from 17 to 33 %. Chlorite and kaolinite are
present in about similar proportions; more specifically
chlorite ranges from 9 to 22 % and kaolinite from 11 to
21 %. Random mixed layers of smectite-illite and chlorite-
smectite are present; often encountered in sapropels and
quantitatively reach the highest percentages (up to 30 %)
above the S-2 layer.

388

ANASTASAKIS

Core CHN-119—31 (Fig. 4) was recovered from the east-

ern distal continental margin of the Nile Cone (Fig. 3) at a
depth of 1637 m. The clay assemblage is dominated by
smectite which ranges from 52 to 65 %. Kaolinite ranks
second in importance and varies from 9 to 22 %. Illite
ranges from 6 to 15 %. Chlorite is present in subordinate
amounts only (less than 5 %). Small amounts of random
mixed layers illite-smectite and probably chlorite-vermic-
ulite are also present.

Lateral and vertical clay mineral variations in the

cores

In the cores under investigation the eastward decrease of

illite is accompanied by a concomitant decrease of the
chlorite content. Kaolinite does not display marked lateral

variations suggesting a similar widespread source area.
The observed lateral changes in the proportions and distri-
bution of the dominant clay groups are in accordance with
the published data on the clay mineralogy of the Recent
and late Quaternary sediments of the region that show
highest scores of smectite close to the Nile and illite en-
hancement towards the northern shores of the East Medi-
terranean Sea (Rateev et al. 1968; Venkatarathnam &
Ryan 1971; Chamley 1972; Emelyanov 1972; Nir &
Nathan 1972; Cita et al. 1977; Dominik & Stoffers 1979;
Maldonado & Stanley 1981; Buckley et al. 1982).

The vertical distribution of clay minerals also displays

important but consistent fluctuations in the cores under
consideration (Figs. 6, 7). In core CHN-119—6, the strati-
graphic level upwards of S-5 displays an important in-
crease of the sum of smectite+kaolinite within sapropels
S-5 to S-1. Two low smectite intervals occur in-between

Fig. 6. Clay mineral variation contents of cores CHN-119—6 and TR-172—19. The simplified, sapropel based lithostratigraphy, is given
alongside with: a – % Sm + K which indicates the relative percentage of smectite plus kaolinite; b – I

I001

K001

—I

CH002

indicates the ratio

of the integrated intensity (peak height) of the 001 illite and the 001 kaolinite peaks. The 001 kaolinite peak intensity was found by divid-
ing the 7

Å peak intensity in proportion to the kaolinite/chlorite ratio of the 3.57 Å and 3.53 Å peaks; c – I

K002

CH004

gives the intensi-

ty ratio of the 002 kaolinite and 004 chlorite peaks (heights). The black dots indicate the sampled interval. Where two samples were taken
at closer than l0 cm intervals, the average clay mineral composition and/or peak intensity is plotted. The solid bars alongside the cores indi-
cate the radiocarbon dated interval.

389

CLAY MINERAL DISTRIBUTION PATTERNS IN THE SOUTHEASTERN MEDITERRANEAN SEA

the sapropel layers S-3 and S-2 as well as S-2 and S-1.
High kaolinite abundances occur below the sapropel S-5
while elevated values of this clay mineral are encountered
in-between the sapropel layer S-4 and S-5. Other varia-
tions include the pronounced increase of illite content in
the uppermost part of sapropel S-4 and to lesser extent
within sapropel S-1 while chlorite contents are relatively
enriched in the upper part of sapropel S-4 and S-5.

The more conspicuous clay mineral distribution in core

TR-172—19 is the stepwise decrease of the sum of
smectite + kaolinite from the sapropel S-5 to within the
sapropel lithofacies S-2 and an increase within sapropel S-1
(Fig. 4). An antithetic relation is observed between smec-
tite-kaolinite and illite-chlorite. Illite contents are mini-
mized below S-4 down to and within S-5 and around the

S-2 while the highest percentages occur within and in-
between S-4 and S-3 layers.

The prominent feature about the clay mineral distribu-

tion in core CHN-119—31 is the gradual upward decrease
of smectite + kaolinite from below the S-4 upwards to the
base of S-1 (Fig. 7). The interval confined between S-4 to
S-3 displays the lowest I/K ratio due mostly to an increas-
ing kaolinite contribution, while the I/K ratio reaches its
highest value between the sapropels S-2 and S-1 due to a
marked increase in illite (Fig. 7). Kaolinite + smectite con-
tents show the most pronounced enrichment within
sapropel layers S-4 and S-1.

Core CHN-119—32 studied by Dominik & Stoffers

(1979), displays comparable clay assemblage trends to
CHN-119—31 (Fig. 7). These variations include a general

Fig. 7. Clay mineral variations in cores CHN-119-32 and CHN-119—31 recovered in the eastern Nile Cone. The clay mineralogy and
lithostratigraphy of core CHN-119—32 are plotted after Dominik & Stoffers (1979). Symbols and other explanations are as in Fig. 6.

390

ANASTASAKIS

decrease in smectite + kaolinite from above sapropel S-4 to
below S-1. Within and in-between the sapropels S-4 and S-3
the sediments display their lowest I/K ratio, due to in-
creasing kaolinite. The highest I/K ratio observed between
sapropels S-2 and S-1 is attributed to a significant increase
in illite content.

Variability with time of clay mineral assemblages

The oldest stratigraphic interval examined in this study

is the organic rich sapropel layer S-5 present in two of the
studied cores (CHN-119—31 and TR-172—19). This S-5
layer (equivalent to E sapropel of Thunell et al. 1977) is
thought to represent cold conditions from the contained
fauna. Based on the new C14 dates (Table 1), sapropel lay-
er S-5 was deposited within the lower pleniglacial
(59,000—73,000 yr BP) equivalent to the Deep Sea record
Stage 4 (Martinson et al. 1987). This early Würmian peri-
od was dry, as shown by low lake water levels, both in
East Africa (Lake Abhe, Gasse 1977) and Central Africa
(Lake Chad, Durand 1982). The deposition of extensive
fluvial sands in basins in East Africa (Central Afar and
South Rift, Gasse et al. 1980) corresponds to high erosion-
high sediment yield. Pollen counts in a core (Conrad-9—174,
Rossignol Strick 1974) recovered from the outer Nile
Cone reveal extremely low contents of tree pollen but
very high grass pollen contents, especially of steppe spe-
cies. The cores studied in this work display the highest
smectite + kaolinite contents within sapropel S-5 (Figs. 6,
7), denoting the increased influence of Nile clay mineral
assemblages as far west as the Mediterranean Ridge south
of Crete. This increase is caused in the Nile Cone mainly
by high smectite contents while in its outer northwest pe-
riphery and further west it is due to higher kaolinite per-
centages. The I/K ratio within S-5, in the Nile Cone and its
outer margin displays reduced values (Figs. 6, 7) caused
by enhanced kaolinite content not matching a concomi-
tant increase in illite. This is attributed to enhanced pro-
portions of wind blown kaolinite rich dust getting into the
Levantine Sea and its eastward transport by the counter-
clockwise gyre (Bergamasco et al. 1992; POEM 19992). In
the western Levantine (core CHN-119—6, Fig. 6) this trend
is reversed due to increased illite percentages transported
by currents from more distant northeastern Mediterranean
sources such as the Hellenic region (Venkatarathnam &
Ryan 1971; Nir & Nathan 1972; Dominik & Stoffers
1979). I/K ratios are generally reduced within the S-5 to
S-4 interval in cores from the outer periphery – distant
province of the Nile Cone area (cores TR-172—19 and
CHN-119—6, Fig. 6), as well as in the vicinity of the Nile
Cone (cores CHN-119—32 and CHN-119—31, Fig. 7).

The influence of Nile clay mineral assemblages persists

within the sapropel S-4 and is further enhanced in the
southeast Levantine area as demonstrated by the fact that
the sum of smectite+kaolinite reaches peak values in S-4
(cores CHN-119—32 and CHN-119—31, Fig. 7). The
sapropel S-4 (equivalent to the sapropel D of Thunell et al.
1977) is faunistically a warm sapropel and pollen counts

within this layer reveal the most elevated tree pollen
counts in the Nile Cone area (Rossignol Strick 1974). The
C14 date obtained from the base of S-4 in core TR-172—19
(Fig. 6) yielded an age of 56,500 yr BP. The extrapolated
age for the deposition of S-4 suggests that it was initiated
well after 55,000 yr BP, within the lowest warming inter-
val of Stage 3. During this period lake levels both in Cen-
tral Africa (Lake Chad, Durand 1982) and East Africa
(Lake Abhe, Gasse 1977) clearly denote highest water lev-
els after 50,000 yr BP, persisting or increasing up to
35,000—32,000 yr BP. Moreover, dating of lake levels in
Upper Egypt, at Bir Tarfani (Kowalski et al. 1989) and au-
thigenic carbonates in nearby paleovalleys (Wadi Arid
and Wadi Safsaf) indicates significantly elevated freshwa-
ter deposits around 45,000 yr BP (Szabo et al. 1989). This
phase of increased rainfalls affected the White Nile drain-
age system as far south as Lake Victoria as demonstrated
by palynology studies on Lake Kivu (Bonnefille et al.
1990) west of Lake Victoria (Fig. 1) This humid interval is
also verified by a Late Pleistocene lacustrine episode, re-
corded in a lake in southeastern Libya and, dated about
40,000 yr BP (Gaven et al. 1981).

Periods of highest sediment yield from the Ethiopian

highlands and lowlands seem to correspond to times of
maximum aridity, minimum water yield, but highly sea-
sonal runoff during the coldest Pleistocene intervals (Ad-
amson et al. 1980). Wetter conditions would have resulted
in increased vegetation cover leading to reduced erosion
and decreased sediment load carried by both the Ethiopi-
an tributaries even if their discharge would have increased
(Foucault & Stanley 1989). According to Butzer & Hansen
(1968a,b), the primary source area of Nile sediments is the
sub-tropical Voina region at an altitude of 1800—2700 m,
in Ethiopia, where vertisols rich in montmorillonitic
(smectite) clay predominate. At higher elevations in the
temperate Dega region, red clay soils with dominantly ka-
olinite minerals predominate. White Nile sediment load
fluctuations are also due to changing climatic/geographi-
cal factors. However, because of a more constant vegeta-
tion cover on its drainage basin during most of the late
Quaternary (Livingstone 1980; Bonnefille & Riollet
1988) and of its extensive swamp area acting as a sedi-
ment trap, its load remained generally low, even when its
discharges increased considerably. During humid periods
when the vegetation cover in the drainage systems of the
Blue Nile and Atbara River increased and their transported
sediment loads decreased, the White Nile sediment contri-
bution increased but nevertheless remained insignificant.

The envisioned scenario regarding clay mineral input

and dispersal pattern in the southeastern Levantine Sea
during the S-5 to S-3 stratigraphic interval directly corre-
lates the observed clay mineral variations, along the cores
mainly to the evolution of the Nile River drainage system.
Thus, increased proportions of Nile clay mineral assem-
blages were transported into the sea during the deposition
of S-5 and of post S-5 sediments. During this arid phase,
the Nile which derived fine-grained fraction exerted a
much stronger and wider influence all over larger areas of
the southeastern Mediterranean Sea. Cores recovered in

391

CLAY MINERAL DISTRIBUTION PATTERNS IN THE SOUTHEASTERN MEDITERRANEAN SEA

the outer periphery of the Nile Cone, as far as the Mediter-
ranean Ridge south of Crete (CHN-119—6, Fig. 3) display
strongly elevated sums of smectite + kaolinite, coupled
with the lowest ratios of illite/kaolinite. This is also an in-
dication of a subdued eastern Mediterranean anticyclonic
water movement, during this cool interval, as illite rich
Ionian Sea waters (Emelyanov & Shimkus 1972; Dominik
& Stoffers 1979) apparently did not deposit clay minerals
in significant amounts in the eastern basin. During and af-
ter the deposition of sapropel S-5 clay mineral wind trans-
port must have exerted a stronger influence on the clay
mineral deposition in the Levantine Sea, as the clay min-
eralogy of cores recovered in the outer periphery of the
Nile Cone and further west displays a significant enrich-
ment in kaolinite.

The cores recovered in the periphery of the Nile Cone

display, upwards within the sapropel lithofacies S-4, the
most elevated smectite + kaolinite sum plus the lowest I/K
ratio due to the enhanced kaolinite contents (Fig. 6). It is
recalled that during the warming trend of the lower part of
Stage 3 which ended in-between events 3.3 and 3.13 ac-
cording to the detailed chronology of Martinson et al.
(1987) in the marine record spans the interval from
59,930 to 44,829 yr BP. During this period there is un-
equivocal evidence for enhanced rainfall throughout the
Nile drainage system. At such times it is also very proba-
ble that an additional drainage region, especially between
Darfur and Tibesti (Fig. 1), comprising the eastern Sahara
Desert along the western flank of the main Nile, became
incorporated into the Nile drainage due to the activation
of large river valleys – wadis (Burke & Wells 1989; Sza-
bo et al. 1989) bringing enhanced kaolinite together with
numerous wadis draining the eastern Desert—Red Sea to
the east that further increased the supply of smectite and
kaolinite. All these factors could have increased signifi-
cantly the supply of sediment into the Lower Nile. Nilotic
provenance assemblages are relatively elevated up to
within the S-3 lithofacies in the Nile Cone cores (Fig. 7).
West of Cyprus there is a marked illite (mainly Mg-rich
trioctahedral-celadonite) and chlorite (possibly including
serpentinite) content increase (Fig. 6) suggesting en-
hanced clay mineral contributions from local sources in
Cyprus and/or northeastern Mediterranean Sea during the
S-4—pre S-2 statigraphic interval (Fig. 6, core TR-172—19).
The I/K ratio displays higher values in the stratigraphic
interval between the sapropel layers S-3 and S-2. The ac-
cumulation of the sediments between the S-3 and S-2
sapropels coincides with the end of marine oxygen iso-
tope Stage 3 (Bard et al. 1990) which is characterized by a
sea-level drop below —80 m. Further to the West, core
CHN-119—6 does not reveal any significant clay mineral
variation within the post S-4—pre S-2 stratigraphic interval.

Towards sapropel layer S-2, the deposition of which is

placed around 23,500 yr BP (Stanley & Maldonado 1977),
all the studied cores show a more or less pronounced de-
crease in the Nile clay mineral assemblages. Moreover, es-
pecially in the distal eastern Nile Cone cores
(CHN-119—31 and CHN-119—32, Fig. 7) there is a marked
increase in the illite/kaolinite ratio caused by enhanced il-

lite percentages. This is attributed to a stronger anticy-
clonic gyre of eastern Mediterranean surface waters, driv-
en by the strengthening of westerly wind directions
(Rognon & Williams 1977) bringing more illite from the
northeastern Mediterranean sources. Nevertheless some
old (27,000—25,000 yr BP) Nile River terraces (Butzer &
Hansen 1968b; El Atar & Jackson 1973) and boreholes
from the delta (Weir et al. 1975) reveal lower values of
smectite and enhanced illite when compared to overlying
uppermost Pleistocene and Holocene sediments.

The sediments between sapropel lithofacies S-2 and S-1

in all studied cores which present the lowest Nilotic prov-
ince clay assemblages (Figs. 6, 7) display an increase of il-
lite-micas. This increase is regular over the entire Nile
Cone area and is more pronounced in the 23,000 to
18,000 yr BP stratigraphic interval (core CHN-119—31,
Fig. 7) which is also characterized by a sharp decrease of
gravitational sediment input on the Nile Cone area as
demonstrated by Maldonado & Stanley (1981). The adja-
cent to the east Israel—Sinai shelf (Stanley et al. 1997,
1998) most probably provided enhanced contributions of
clay minerals such as illite and mixed layers. Moreover in
the wider Nile Cone area and its present day Nile Delta
this time interval is characterized by higher percentages of
kaolinite (Maldonado & Stanley 1981; Abdel Wahab &
Stanley 1991). Although enhanced illite contents suggest
a general decrease of soil formation, both in upstream and
downstream areas (Chamley et al. 1986) this assumption,
on the basis of the observed sediment yield, cannot be
concluded for the Nile drainage system. Adamson et al.
(1980) and Williams & Adamson (1980) pointed out that
the relatively dry, cold conditions around the Nile head-
waters between 20,000 and 13,000 yr BP and low total but
high peak discharges by the Nile drainage, are consistent
with high sediment input to the headwaters and the down-
stream aggradation as far as Egypt.

Thus there are indications suggesting that there was a

decrease in the amount of suspended sediment carried into
the East Mediterranean by the Nile, despite the fact that
the total sediment yield may have been high. The en-
hanced kaolinite content in the stratigraphic interval un-
der discussion may be due to wind transport of kaolinite
(Chester et al. 1977; Stanley & Wingerath 1996). The in-
creased I/K ratio and the lowest percentages of the sum of
Sm + K during the post S-2 to pre S-1 stratigraphic interval
might record both the diminution of the supply of sus-
pended sediment by the Nile added to the effects of a low-
ering base level of erosion during the last major sea-level
drop, around 18,000 yr BP (Berger et al. 1985). As a result
the climatic signal that may be inferred from the changes
in the composition of clay minerals is believed to have
been severely reduced during major sea-level cycles as
demonstrated by Chamley (1983). Such effects were even
more dramatic in the case of the Nile Delta where, during
this time span, eustatic changes involving fluctuation
ranging from a maximum 1ow to a maximum high sea lev-
el entailing an extensive migration of the Nile Delta depo-
centers on the Egyptian shelf (Summerhayes et al. 1978;
Coutellier & Stanley 1987). Clay mineral studies of the

392

ANASTASAKIS

Nile Delta (Abdel Wahab & Stanley 1991) suggest that the
Late Pleistocene Nile River transported northward grow-
ing proportions of kaolinite and decreasing amounts of
smectite. Moreover due to the transgressive erosional
phase the post 18,000—pre 12,000 yr BP time span in the
Nile area is characterized by similar clay mineralogy.

However, the most pronounced clay mineral variations

in this stratigraphic interval occur in core TR-172—19
which consistently displays the highest I/K ratio (Fig. 6).
Moreover, in this core, sediments between the sapropels S-2
and S-1 contain a high percentage of random mixed layers
most notably of illite-smectite. The enhanced supply of
illite and mixed layers is most plausibly attributed to the
input of increased amounts of clay minerals derived from
Cyprus and its margin (Fig. 8). The margin south-south-
west of Cyprus is characterized by low upper Quaternary
sedimentation rates (Buckley et al. 1982) plus intense
recent tectonic activity (Anastasakis & Kelling 1991).
Thus sediment erosion and removal during the main low
sea-level stand at about 18,000 yr BP, reaching the deeper
layers in near coastal areas is demonstrated by similar cas-
es elsewhere (Diester-Haas & Chamley 1980). The illite
plus mixed layers enrichment in core TR-172—19 requires
a mechanism for clay mineral transport from the Cyprus
shelf into the Levantine area. The most plausible mecha-
nism is a strengthening of the anticyclonic, sub-basin
scale gyre known to exist west-southwest of Cyprus

(Moskalenko 1974; Gerges 1977; Ozsoy et al. 1989; Rob-
inson et al. 1991). Thus it apperars that during major sea-
level falls, like during Stage 2, surrounding exposed
continental shelfs to the north and the east of the Nile
Cone had an enhanced impact on the clay mineral compo-
sition of the southeastern Mediterranean Sea.

The distribution pattern of the clay mineral groups with-

in the uppermost sapropel layer S-1 reflect an abrupt and
increased influence of clay minerals of Nilotic prove-
nance, especially smectite (Figs. 6, 7). In the southwestern
Levantine Sea (core CHN-119—6, Fig. 6) the increase of
smectite, within the S-1, is accompanied by a concomitant
increase of illite, mostly derived from the eastward inflow
of Ionian illite-rich waters (Dominik & Stoffers 1979). This
illite enrichment diminishes west of Cyprus and does not
affect the clay mineralogy of the Nile Cone cores (see also
Maldonado & Stanley 1981) which displays an additional
enrichment in smectite and kaolinite further east. This
stratigraphically latest change in the clay mineralogy of the
studied cores records the extraordinary amount of suspend-
ed sediments brought into the southeastern Mediterranean
Sea by extensive Nile River floods. After 12,500 yr BP, an
extensive overflow from Lake Victoria (Fig. 1) into the
White Nile and higher rainfalls in Ethiopia (Adamson et al.
1980) drastically affected sedimentation in the Nile Cone
area resulting in a proportional increase in the role of
hemipelagic sedimentation (Stanley & Maldonado 1977).

Fig. 8. General physiography, water mass motion and main clay mineral supply routes in the Levantine Sea. The different arrows (de-
fined in legend) indicate the dominant water mass movements plus the sources and the dispersal patterns of clay minerals.

393

CLAY MINERAL DISTRIBUTION PATTERNS IN THE SOUTHEASTERN MEDITERRANEAN SEA

Radiocarbon dating of southeastern Levantine cores
indicate that accumulation of the sapropel S-1 begun at
about 11,800 yr BP (uncorrected C14 dates, Anastasakis &
Stanley 1986), which roughly coincides with Nile
flooding that caused a significant increase of smectite and
to a lesser extent, kaolinite contents. This enhanced Nile
assemblage influence persists throughout the sapropel S-1,
whose deposition ended at about 7000—6000 yr BP. Post
S-1 sediments display reduced sums of smectite and
kaolinite but the relative percentages of kaolinite tend to
increase. This is an indication that after 7000 yr BP the
relative contribution of wind blown kaolinite increased.

Summary and conclusions

The vertical clay mineral fluctuations in cores recovered

in the Nile Cone that are dominated by upper Quaternary
hemipelagic sedimentation reflect the supply of suspend-
ed matter yield by the Nile. The most pronounced increase
in proportions of the Nile derived clay minerals resulted
from significantly enhanced suspension loads conveyed
by the Nile River during the transition from dry to wet cli-
matic periods. Smectite and kaolinite are the predominant
clay minerals of Nilotic East African (Ethiopian) origin.
The pronounced abundance of these clays infers a Nilotic
provenance that is recorded within and in between
sapropel layers S-5 and S-4. These correspond to a time in-
terval ranging between 70,000 and 45,000 yr BP and mark
the transition in the marine sediments from the cold Stage 4
to a warming trend displayed by the lower part of Stage 3
(Imbrie et al. 1984). The Nile drainage system experienced
a similar phase resulting in a dramatic increase of the Nile
suspension load into the eastern Mediterranean Sea. As a
result, clay mineral assemblage within the sapropel S-5 re-
veals the highest contribution of smectite and kaolinite
associated with extremely low I/K ratios. For sapropel S-4,
the eastern Nile Cone displays high contents of smectite
and kaolinite while westwards, in the Levantine Sea, there
is a sharp increase in the I/K ratio. This resulted from the
maximum wet phase, which affected the Nile drainage sys-
tem, intensified around 45,000 yr BP and probably
activated numerous wadis especially along the western
flank of the Lower Nile. The observed westward increase,
within the S-4, of the I/K ratio is a strong indication that
there was a gradual increase of the Levantine waters that
brought a larger amount of illite from the northwest.
Upwards, within the sapropel S-3, the proportions of Nile
clay minerals slowly declined in the Nile Cone and so
recording the decrease of suspension delivered by the Nile
into the Levantine Sea. This resulted from the dry phase
experienced by the White Nile drainage basin coupled
with the continuing humid conditions that prevailed over
the Blue Nile and Atbara Depression and led to a net
reduction of the suspension delivered by the Nile. The
pronounced lower percentages of smectite and the signifi-
cant increase in illite contents observed between sapropels
S-2 and S-1 indicate both a diminution of the sediment de-
livered by the Nile into the Levantine Basin and the en-

hanced contribution of the surrounding continental shelfs
to the North and the East due to lowered sea level. The last
major sea-level drop around 18,000 yr BP lowered the
base level of erosion and increased the proportion of illite-
micas plus mixed layer illite-smectite. Hence the climatic
signal that would have been inferred from the clay mineral
changes is severely obliterated. The pronounced increase
in the Nile clay mineral assemblages within the S-1 re-
flects the dramatic increase of suspended sediments deliv-
ered by the Nile and related to extensive floods in the
drainage systems, from about 12,500 to 6000 yr BP. After
6000 yr BP enhanced contributions of wind blown kaolin-
ite are recorded.

Acknowledgments: I thank the Woods Hole Oceanograph-
ic Institution and the University of Rhode Island for gen-
erously allowing me to sample their core collections.
Special thanks are due to Dr. Daniel J. Stanley, Smithso-
nian Institution, who organized much of the data acquisi-
tion. Appreciation is expressed to H. Sheng for assisting in
the Smithsonian Laboratory and Dr. R. Stuckenrath for
providing the radiocarbon dates published in this study.
The manuscript was improved after thorough reviews by
D.J. Stanley, Smithsonian Institution, G. Kelling, Keele
University, F. McCoy, University of Hawai. V. Lykousis,
National Centre for Marine Research, read an earlier ver-
sion of the manuscript. This manuscript was improved by
four anonymous reviewers for the journal.

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