Although the type sections of most stages of the Kahmah series (or of the "Thamama", almost a time-equivalent) of the Middle-East regional succession were recently revised and the definitions of their upper and lower boundaries were either definitively legitimized or slightly emended (Granier, 2000, et seq.), some authors continue to use incorrect information and to make interpretations therefrom that are in conflict with the valid data now to hand. So we post new stratigraphic findings concerning the Lekhwair(-ian) and Hawar(-ian) regional stages of the Lower Cretaceous in (the U.A.E. and) Oman:

1. in Oman oolitic facies referred to as the "Habshan Formation" are interfingered in the outer platform to slope facies of the Salil Formation. These shoal facies are diachronous for they record the seaward shift of successive progradational wedges, a migration caused by regular or forced regressions (see Lebec, 2004, for instance). This so-called "Habshan Formation" in Oman was mistakenly correlated with the type Habshan of Abu Dhabi (Hassan et alii, 1975; ...) as briefly explained below:
   • in its type locality, well Zakum-1 of the Abu Dhabi offshore, oolitic (grain-supported) facies are rare in the predominantly mud-supported microfacies (characteristic of the innermost parts of the platform), and
   • microfossil (calcareous algae and foraminifers) assemblages are either of Tithonian and Berriasian age in the Habshan as defined by Hassan et alii (1975) or they are restricted to the Tithonian alone in the Habshan as emended by Granier (2000). In Oman microfossil assemblages of the so-called "Habshan" are of Hauterivian and Early Barremian age. Therefore, in Oman the time-span of the so-called "Habshan" is actually within that of the Lekhwair regional stage.
2. in the ADMA offshore field 'A' (Granier et alii, 2003), the Hawar is a 25' thick depositional sequence: most of it was laid down as a transgressive systems tract, but the uppermost 2.5, a thin shaly interval was deposited during a highstand systems tract. As stated by Granier (2008): "The upper limit of the Hawar Formation is coincident with an abrupt change in sedimentation from the uppermost shale (...) to very shallow-water carbonates (...). As does the lower boundary, the upper one records a forced regression: the fall in sea level can be estimated to have been 40 meters or more". To date most authors have overlooked this major sequence boundary. But they also did not recognize other key markers. For instance, the occurrence of the foraminifer Choffatella in the upper half of the TST support its use as an index characterizing relatively deeper-water environments. In Oman, at Wadi Bani Kharus, the Hawar interval attains a thickness of 25 meters (van Buchem et alii, 2002), more than three times that of the time-equivalent section in the Emirian offshore field. However Choffatella is restricted to the first five meters of this onland unit. This fact contradicts sequential interpretations of authors who consider the Hawar to be either the TST of a higher scale sequence extending into the Shu'aiba or the lower part of this TST. Granier et alii (2010) defined the maximum flooding surface of the Hawar sequence to be near the 5 meter mark. With respect to stratonomy, the Hawar sequence is highly asymetrical in Oman. Its pattern is reversed from that of field 'A' (thick TST and thin HST): at Wadi Bani Kharus the TST is thin and the HST is thick.

These new biostratigraphic data document explicitly the geometries observed in the Lekhwair (i.e., the diachronism of the prograding clinoforms) and that of the Hawar (i.e., one third-order depositional sequence) thus permitting recognition of the significance of these relationships for petroleum geology.