Recognition of the diagenetic features of the late Jurassic Haifa carbonates, central Saudi Arabia

Abstract EN

The diagenesis of Late Jurassic Hanifa carbonates, central Saudi Arabia was studied petrographically in detail.

This formation has been divided stratigraphically into three members, the lower ledges, the middle slope and the upper ledges.

The lower-most brown ledges in the section comprise a series of coarsening upward sequences which generally terminate in a fossiliferous/peloidal packstone and grainstone and subordinately lime mudstone facies.

The middle slope member is yellow, blocky weathered shale and marl.

Above this slope member are several thick beds of brown coated fossiliferous wackestone, packstone and grainstone with the association of lime mudstone in certain levels.

These are fairly resistant ledges due to the occurrence of stromatoporoids.

The Hanifa Formation shows various diagenetic features.

These include dolomitization, dedolomitization, micritization, cementation and recrystallization.

Most of the examined samples of the Hanifa carbonates are dolomitized and subsequently dedolomitized as evidenced by the presence of iron coated dolomite rhombs partially or completely calcitized.

Dolomite also occurs in the lime mudstone, wackestone, packstone and grainstone facies, while leaching of wackestone and packstone and dedolomitization of dolomite and dolomitic limestone followed by recrystallization are common processes.