After sea level rises during the Early Cretaceous,
upper parts of the Khami Group sediments (Fahliyan,
Gadvan, and Dariyan Formations) deposited over
Jurassic sediments. The Lower Cretaceous (Aptian) Dariyan
Formation (equivalent to the Shu’aiba Formation and
Hawar Member of the Arabian Plate) carbonates, which
have hydrocarbon reservoir potential, form the uppermost
portion of the Khami Group that unconformably overlays
the Gadvan Formation and was unconformably covered by
the Kazhdumi Formation and Burgan sandstones. Detailed
paleontological, sedimentological, and well log analysis
were performed on seven wells from Qeshm Island and
offshore in order to analyze the sequence stratigraphy of
this interval and correlate with other studies of the Dariyan
Formation in this region. According to this study, the
Dariyan Formation contains 14 carbonate lithofacies,
which deposited on a ramp system that deepened in both
directions (NE—wells 5, 6 and SW—wells 1, 2). Sequence
stratigraphy led to recognition of 5 Aptian third-order sequences
toward the Bab Basin (SW—well 1) and 4 Aptian
third-order sequences toward Qeshm Island (NE—wells 5
and 6) so these areas show higher gamma on the gamma
ray logs and probably have higher source rock potential.
Other wells (wells 2–4 and 7) mainly deposited in shallower
ramp systems and contain 3 Aptian third-order sequences.
On the other hand, rudstone and boundstone
lithofacies of studied wells have higher reservoir potential
and were deposited during Apt 3 and Apt 4 sequences of
the Arabian Plate. The Dariyan Formation in Qeshm Island
(well 6) and adjacent well (well 5) was deposited in an
intrashelf basin that should be classified as a new intrashelf
basin in future Aptian paleogeographic maps. We interpret
that salt-related differential subsidence, crustal warping,
and reactivation of basement faults of the Arabian Plate
boundary were responsible for the creation of the intrashelf
basin in the Qeshm area.