Abstract: Tectonic Evolution of the Red Sea and Gulf of Suez Rift Systems
MCCLAY, KEN R., ARCO Professor of Structural Geology, Royal Holloway University of London, UK
The northern Red Sea and Gulf of
Suez rift system is the northwestern termination of the northwest arm of
the Neogene Gulf of Aden, northern Ethiopian and Red Sea rift systems formed
by the north-northeastward separation of the Arabian plate from the African
plate. The onshore northern Red Sea margin and the flanks of the Gulf of
Suez provide some of the best exposed examples of rift extensional fault
systems and associated synextension marine sedimentation in the world.
The Gulf of Suez is a major hydrocarbon province with several giant oil
accumulations trapped in extensional
fault
blocks within the rift basin.
The northern Red Sea-Gulf of Suez rift system is developed on Pan African
igneous and metamorphic basement with a thin, prerift, Phanerozoic-Mesozoic-Paleogene
sedimentary cover. Preexisting
fault
systems, basement fabrics, and basement
terrane boundaries have exerted a strong control on the Neogene rift architecture.
The northern Red Sea and Gulf of Suez rift system
is characterized by northwest and north-northeast-trending rift border
and intrarift extensional faults that form distinct rhomboidal patterns.
Rifting initiated in the Late Oligocene-early Miocene (Chattian-Aquitanian)
with the formation of thin generally continental red beds accompanied by
volumetrically minor basaltic volcanism. In Aquitanian times the sedimentation
was dominantly shallow to marginal marine--generally coarse-grained conglomerates
and sands at the rift margins and finer grained mudstones and marls toward
the center of the rift. In detail individual fault
blocks within the rift
system experienced different structural and stratigraphic evolutions. The
greatest synrift sedimentation occurred in the Burgidalian (the so-called
rift climax) with thick accumulations of Globigerina marls and shales in
the central rift basins. In the late Serravallian the rift subbasins became
isolated from open ocean circulation and thick evaporite deposits were
formed. In the Pliocene to recent normal marine conditions prevailed with
connection to the Indian Ocean via the Red Sea-Gulf of Aden.
The extensional fault
systems of the northern
Red Sea-Gulf of Suez are spectacularly exposed along the rift margins.
Basement cored domino-style tilted
fault
blocks occur in four distinct
dip domains from the northern Red Sea into the Gulf of Suez. Complex accommodation
zones separate these dip domains. Individual faults, both at the rift borders
and within the rift, consist of linked segments. Overlapping faults form
relay ramp structures, and transfer faults are formed where relay ramps
are broken along preexisting basement fabrics. Evolutionary models are
proposed for the development of the northern Red Sea and Gulf of Suez
fault
systems. Structural styles within the Red Sea and Gulf of Suez rift are
compared and contrasted with the results of scaled analog models and with
extensional
fault
systems in the east African and North Sea rifts.
AAPG Search and Discovery Article #90912©1999-2000 AAPG International Distinguished Lectures