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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: The Suez Rift:
Structural Pattern and Evolution
By
After a regional presentation of the Gulf of Suez, a thermomechanical model of the rift evolution will be presented.
Then we will examine some structural problems related to extensional tectonics as the internal deformation of tilted blocks.
Two main types of deformation are generally considered
in extensional terranes: (1) faulted blocks are rigid and
deformation consists of translations and rotations; (2)
blocks are pervasively deformed, by simple shear along
closely spaced minor faults or by "flexural slip" parallel to
bedding planes. To evaluate the amount of such pervasive
deformation field measurements were performed across
three major tilted blocks of the Suez rift (Abu Durba and
Araba-Qabeliat blocks) and Red Sea (Duwi block
). They
consist of narrow (15 to 20 km wide) elongated (30 to 60 km
long) monoclines dipping to the northeast and bounded by
major southwest dipping faults which have vertical displacement
of about 2 km. Tilt angles vary from 15 to 20°.
Secondary normal faults are scarce, widely spaced and their
throw comprises between 10 cm. to 150 m. No pervasive and
closely-spaced faults with centimetric or metric throws have
been observed.
In the Abu Durba and Duwi blocks the amount of
extension due to secondary faults is less than 7% while it is
almost null across the Araba-Qabeliat block
. Extensional
models inducing pervasive deformation of blocks by vertical
or oblique simple shear are irrelevant when tilt angles do not
exceed 20° and rigid rotation can be applied to restore the
cross-section. Moreover, most of the observed secondary
normal faults have the same dip direction as major bounding
faults. This arrangement suggests that tilting occurs over a
ductile crustal layer which accommodates at depth the
volume problems caused by rigid
block
rotation.
End_Pages 16 and 19---------------