The Pleistocene of the Red Sea
21
When, about 30 years ago, the evidence for the important eustatic sea level
fluctuations was generally accepted, conclusions for the Red Sea were immediately drawn. Sewell (1948) expressed the view that the sill (about 100 m deep) of
the Hanish Islands (north ofBab el Mandab) was dry in glacial times and that the
Red Sea became isolated from the Indian Ocean. Under such circumstances the
author assumes that two hypersaline lakes were left in the basin and all the
marine fauna died out. The Red Sea, according to Sewell, was repopulated with
marine biota at the end of the Pleistocene. Klausewitz (1960, 1964) is inclined to
consider complete annihilation of the fauna through interruption of the oceanic
connections for the fIrst two glacial periods only, but does not exclude the possibility of a late, Pleistocene reestablishment and permanence of the marine biota.
Emeryet al. (1969) accept the fact that there were in the Pleistocene long periods
"during which the Red Sea basin was occupied by a large isolated lake that
underwent progressive evaporation". Emery and his co-authors consider that the
leaking out ofthese brines, which were also probably sun-heated, gives the source
for the hot brines which are reported from the depths of the Red Sea. Neumann
(1966), however, is inclined to pI ace this brine basin in pre-Quatemary times. The
latest data ofDSDP (see p.15) give full suppmt to this view.
Gohar (1954) already expressed doubts regarding the hypersaline Pleistocene
extermination of the Red Sea fauna, simply on the grounds that the sequence of
the coral reefs does not show such an interruption. This author expresses his
conviction that there was a "continuity of life in the Red Sea at least from the
Pleistocene period until now". This seems to be true albeit in a much modrned
version.
Emiliani (1961) summarized the then-known data about the amplitude of
Pleistocene climatic cycles at low latitudes. Based on 0 18 ratios in foraminiferan
shells, he calculated glacial-interglacial temperature fluctuations of 7-8° C in the
Caribbean and 3-4° C in the Equatorial Pacific. He also generalized on the work
of several authors stating that at low latitudes the glacial climate was arid rather
than "pluvial".
A clear picture of the last 80,000 years of the Red Sea-i. e. from the RissWürm Interglacial to recent times-was obtained by micropaleontologists studying cores of the hot brine area. Hot brines of up to 56S C and a salinity of 257%0
have been found at depths of approximately 2000 m around parallel 21°. Analysis
of the cores did little to explain the origin of the hot activity. Nevertheless, the
start of the hot extrusions could be set by Deuser and Degens (1969) at 11,000
years BP (Before Present) and by Emery et al. (1969) at 12,000 BP.
On the other hand the micropaleontological material collected in the deep
cores of the "Chain" in the fall of 1966 gave a clear picture for the period extending from about 80,000 BP to the present. Of special importance were cores 118 K
and 119 K in the hot brine area and core 154 P about 100 miles south. Coccolithophorids, dinoflagellates, radiolarians, foraminiferans and pteropods were analyzed
in the cores and the data have been summarized by Deuser and Degens (1969) and
by Berggren (1969). Besides the radiocarbon dating, 0 18 /0 16 ratios for paleotemperatures were analyzed as weIl as some microcbemical data.
The results indicate that between 80-50,000 BP, aperiod roughly extending
between the Riss-Würm or Eemian Interglacial and the early Würm or Plenigla-
21
When, about 30 years ago, the evidence for the important eustatic sea level
fluctuations was generally accepted, conclusions for the Red Sea were immediately drawn. Sewell (1948) expressed the view that the sill (about 100 m deep) of
the Hanish Islands (north ofBab el Mandab) was dry in glacial times and that the
Red Sea became isolated from the Indian Ocean. Under such circumstances the
author assumes that two hypersaline lakes were left in the basin and all the
marine fauna died out. The Red Sea, according to Sewell, was repopulated with
marine biota at the end of the Pleistocene. Klausewitz (1960, 1964) is inclined to
consider complete annihilation of the fauna through interruption of the oceanic
connections for the fIrst two glacial periods only, but does not exclude the possibility of a late, Pleistocene reestablishment and permanence of the marine biota.
Emeryet al. (1969) accept the fact that there were in the Pleistocene long periods
"during which the Red Sea basin was occupied by a large isolated lake that
underwent progressive evaporation". Emery and his co-authors consider that the
leaking out ofthese brines, which were also probably sun-heated, gives the source
for the hot brines which are reported from the depths of the Red Sea. Neumann
(1966), however, is inclined to pI ace this brine basin in pre-Quatemary times. The
latest data ofDSDP (see p.15) give full suppmt to this view.
Gohar (1954) already expressed doubts regarding the hypersaline Pleistocene
extermination of the Red Sea fauna, simply on the grounds that the sequence of
the coral reefs does not show such an interruption. This author expresses his
conviction that there was a "continuity of life in the Red Sea at least from the
Pleistocene period until now". This seems to be true albeit in a much modrned
version.
Emiliani (1961) summarized the then-known data about the amplitude of
Pleistocene climatic cycles at low latitudes. Based on 0 18 ratios in foraminiferan
shells, he calculated glacial-interglacial temperature fluctuations of 7-8° C in the
Caribbean and 3-4° C in the Equatorial Pacific. He also generalized on the work
of several authors stating that at low latitudes the glacial climate was arid rather
than "pluvial".
A clear picture of the last 80,000 years of the Red Sea-i. e. from the RissWürm Interglacial to recent times-was obtained by micropaleontologists studying cores of the hot brine area. Hot brines of up to 56S C and a salinity of 257%0
have been found at depths of approximately 2000 m around parallel 21°. Analysis
of the cores did little to explain the origin of the hot activity. Nevertheless, the
start of the hot extrusions could be set by Deuser and Degens (1969) at 11,000
years BP (Before Present) and by Emery et al. (1969) at 12,000 BP.
On the other hand the micropaleontological material collected in the deep
cores of the "Chain" in the fall of 1966 gave a clear picture for the period extending from about 80,000 BP to the present. Of special importance were cores 118 K
and 119 K in the hot brine area and core 154 P about 100 miles south. Coccolithophorids, dinoflagellates, radiolarians, foraminiferans and pteropods were analyzed
in the cores and the data have been summarized by Deuser and Degens (1969) and
by Berggren (1969). Besides the radiocarbon dating, 0 18 /0 16 ratios for paleotemperatures were analyzed as weIl as some microcbemical data.
The results indicate that between 80-50,000 BP, aperiod roughly extending
between the Riss-Würm or Eemian Interglacial and the early Würm or Plenigla-