The late Miocene climate of northeastern Africa: unravelling the signals in the sedimentary succession

Abstract

Examination of the depositional profile of the Miocene/Plio-Pleistocene succession at two locations in the Gulf of Suez and seven locations in the Red Sea leads to the conclusion that the Messinian (Zeit Formation and equivalent) sedimentary rocks were deposited at a rate greater than other units of the Miocene/Plio-Pleistocene in these areas. The Zeit Formation contains a significantly higher clastic content than the underlying South Gharib Formation. These two aspects of the stratigraphy are taken to indicate that the Messinian was a time of high rainfall and high sediment yield rates. This period, named the Zeit Wet Phase, stands in marked contrast to the arid conditions of the preceding Tortonian Stage. The latter stage is represented in the Gulf of Suez and Red Sea area by the halite-bearing South Gharib Formation and its equivalents. Physical evidence for a humid Messinian is provided by five lines of evidence involving four sites around the Red Sea and two sites offshore. It is suggested that the Zeit Wet Phase was marked by high monsoonal activity as demonstrated by drilling sites of the Ocean Drilling Program. It is probable that the wet phase peaked in the late Messinian at the time of the low-stand of the Mediterranean during the Messinian Salinity Crisis.

Tracking provenance change during the late Miocene in the eastern Mediterranean using geochemical and environmental magnetic parameters

“…The humid North African cluster became dominant after ∼8.15 Ma, along with an increasing contribution from the marine productivity cluster. The marine productivity cluster also has low Ti/Al values, therefore there appears to have been a change toward less aeolian input from North Africa, which is consistent with a previously proposed shift toward more humid conditions in North Africa during the late Miocene [e.g., Ruddiman et al , 1989; Griffin , 1999].…”

Isostatic response and geomorphological evolution of the Nile valley during the Messinian salinity crisis

“…Before the MSC, it is believed that the drainage of southern Egypt was dominated by a river (River Qena) that drained southwards east of the present River Nile [Issawi and McCauley, 1992;Goudie, 2005]. Geomorphological and sedimentary arguments, climate modelling and isotopic analysis suggest that a humid climate may have existed during the Late Miocene in North Africa [Griffin, 1999;Segueni, 2007;Gladstone et al, 2007]. The successive reorientation of the drainage pattern toward its present-day configuration could be due (i) to the capture of the River Qena by the headward erosion of the Eonile that was flowing more north [Goudie, 2005] during the MSC, (ii) to a dramatic change of the climatic conditions during this period [Griffin, 1999;, or (iii) to a tectonic evolution of northeastern Africa.…”

“…These sediments were deposited in the Nile delta during the MSC. The Qawasim formation overlies earlier mainly marine Miocene sediments [Griffin, 1999] and was deposited during the Messinian draw-down of the eastern Mediterranean [Abdel et al, 2000]. This sequence is composed of layers of sands, sandstones and conglomerates interbedded with occasional clay beds.…”

Late Miocene and Pliocene large land mammals and climatic changes in Eurasia

“…Of particular interest in the continental-scale sequence is the return to more humid conditions in northern China in the latest Miocene, coinciding in time with evidence of strengthened monsoon circulation at about 8 Ma (Molnar et al, 1993;Rea et al, 1998;Griffin, 1999). While we do not necessarily wish to claim a causal connection here between the increased humidity in eastern Asian and the contemporaneous humidity decrease of western Europe, we do wish to point out that general circulation models as well as partial models like the desert/monsoon system described by (Griffin, 2002) do require that the same change in circulation pattern will have different and often opposite effects in different regions.…”