Page 146 - Life & Land Use on the Bahrain Islands (Curtis E Larsen)

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coasts in the area.
The faulting present in the Gulf of Bahrain affects Miocene
possibly Pliocene rocks (Kassler 1973). In Abu Dhabi, for example, the former r
are affected by parallel, closely spaced,
north-northwest oriented fracturo^*
Faulting along these has caused elongation of outcrops in this direction, In addition
to faulting, gentle Zagros folds are present. The mouth of the Gulf of Bahrain, for
example, is marked by a series of small anticlines and synclines superimposed on a
larger broad anticline, referred to as the Bahrain ridge. An adjacent broad synclin®
occupies the inner portion of the Gulf of Bahrain. This fold is cut by a series of
parallel normal faults (fig. 22).
Upward growth of the Bahrain ridge during the Quaternary period
produced changes in the coastal areas around Bahrain, Some upward growth of
domal structures also took place on the Qatar Peninsula followed by a presumed
peneplenation of the peninsula by higher than present Pleistocene sea levels
between 500,000 and 100,000 years ago (Kassler 1973). Subsidence of the Gulf of
Bahrain was also a Quaternary feature according to Kassler. The most recent
tectonic movements, however, have been attributed to the Bahrain ridge. Varney
(quoted in Kassler 1973) claims that this fold has been rising in the last few
thousand years, a case partially substantiated by the presence of submerged
Holocene marine platforms at -9 m and -18 m which argue for direct connection
with the sea at these depths. Kassler points out that the present configuration of
the Bahrain ridge across the mouth of the Gulf of Bahrain would not have
permitted the entry of marine waters until a threshold depth of -7 m was reached.
Kassler would like to date this upward movement along the fold between 5000 and
6000 years ago based upon the Fairbridge (1961) eustatic sea level curve which
assigns -9 m and -18 m low sea level stands between 7000 and 9000 years ago.
Kassler also notes that this view may be biased by coral deposited on the surface of
the ridge. Other supportive evidence for late Quaternary uplift of the Bahrain
ridge has been presented by Ridley and Seeley (1979), who have dated raised marine
terraces along the Arabian coast near al-Jubail to approximately 3800 radiocarbon
years ago. Bibby (1969, 1971, 1973) also noted uplifted TJbaid settlements in the
same area. Additional evidence for possible uplift along the Bahrain ridge has been