Page 145 - Life & Land Use on the Bahrain Islands (Curtis E Larsen)

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These north-south trending folds are referred to as the Arabian fold pattern.
Bahrain shows this same north-south fold pattern. The origin of the major
anticlines is not clearly understood, but Powers et al. (1966) suggest that they may
relate to deep-seated horstlike uplifts. This interpretation is supported by gravity
data, but simple compression has not been ruled out. Two structures, the Dammam
dome and the Bahrain dome are exceptions. Both display normal faulting along
their crests, and the Dammam dome displays a strong negative gravity anomaly.
Both domes are often regarded as salt-intrusion structures. The Bahrain dome is
asymmetrical, suggesting compressional forces from the east (Willis 1967).
The most striking characteristic of Arabian folds has been their prolonged
upward growth. Kassler (1973) noted that in some cases movements began as early
as the Permian period and lasted throughout the Tertiary period. Movements may
have been pulsatory. The flanks of the structures have low dips on the order of 10
degrees. Hie most recent tectonic event in the gulf region was the Zagros orogeny,
which began during the Pliocene and continued into the Pleistocene. Hiis period of
mountain-building was responsible for the complex folding and uplift of the Zagros
Mountains as well as for the formation of the Arabian Gulf (Kassler 1973).
Although the Zagros orogeny resulted in only subdued folding on the Arabian
Peninsula, it is possible to identify folds that parallel the Zagros fold system.
Among the more prominent of these is a series of gentle north west-southeast
trending folds superimposed on the pre-Pliocene north-south Arabian fold pattern.
Hiese trends are shown in Figure 22. Haynes and McQuillan (1974) have shown the
minor effects of the Zagros orogeny on the edge of the Interior Platform of eastern
Arabia. While minor broad folding is in evidence, the region has been relatively
stable since the Pliocene.
Tbe region of most interest here is the Gulf of Bahrain which lies between
the Arabian coast at Dhahran and the west coast of the Qatar Peninsula. Kassler
(1973) shows the Gulf of Bahrain to be outlined by normal faulting, Hie most
prominent faults parallel the Arabian coast from Dohat Dhalum southeastward to
Salwa at the south end of the embayment. The west coast of Qatar is also largely
determined by faulting. Hius, normal fault blocks give rise to the distinctive linear