## 4 Results  
### Texture and Lithofacies  
The Hanifa Formation in the study area mainly consists of mudstone and bioclastic wacke- to packstone in the lower part (Hawtah member), and pack-to grainstone units with some coral reef fragments in the upper part (Ulayya member). A detailed description of lithofacies and the depositional environment of the Hanifa Formation can be found in [57]. In this study, we tried to use the texture mainly to differentiate between lithofacies. Hence, five lithofacies were identified:  
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2. Mudstone. Massive and thickly bedded, light grey to brown, burrowed mudstone. Skeletal grains are common and in most cases are dominated by scattered sponge spicules and scattered benthic foraminifera, and bivalve and brachiopod fragments (Figure 3A). 3. Wackestone. White to beige massive beds with fine texture and high level of hardness. The sediments of this facies are well distributed throughout the studied stratigraphic section. The wackestones are rich in sponge spicules and in a few cases, show jasper chert nodules. It also contains scattered fragments of bivalves, echinoderms, brahiopods, and agglutinated foraminifera (especially the species _Kurnubia palastitiiensis_) (Figure 3B). However, in general, it is similar to the mudstone lithofacies but with a higher abundance of skeletal grains, and the sediments show a higher bioturbation intensity with abundant _Thalassioides_ burrows. Mudstones and wackestones are more dominant in the lower part of the formation. 4. Packstone. Massive beige beds mainly comprising skeletal grains of foraminifera, bivalves and sponge spicules, quartz grains, oncoids and peloids (Figure 3C). The  
Figure 2: Bioturbation estimation using CT scan. (**A**) Plug photo showing the _Thalassioides_ burrow highlighted by a dotted red line. (**B**) 3D CT scan view of the studied sample showing the bioturbation network within the plug. percentage of each skeletal and non-skeletal grain type varies considerably based on the associated lithofacies. The packstone lithofacies occur together with the sponge spiculitic skeletal wackstones, the peloidal grainstones, and the reefal lithofacies. * Grainstone. This facies caps the sedimentary cycles in both the upper and lower parts of the studied succession. However, their abundance is more frequent within the upper cycles. The grainstone beds are massive, horizontally laminated and show trough cross-bedding; and at times, the beds have an erosive base. The sediments are brownish in color and mainly composed of peloids, combined with angular fine quartz grains and scattered skeletal grains, mainly bivalves (Figure 3D). * Reefal lithofacies. The main reef builders found in the Oxfordian Hanifa succession are scleractinian corals in addition to demosponges, especially, stromatoporoids (Figure 3E). These reef builders are found either in association forming a mixed coral/stromatoporoid framestone, rudstone (Figure 3F), or do occur independently, forming their own buildups. Both coral and stromatoporoid fragments are found scattered in a floatstone texture, with a skeletal wackestone/packstone matrix. The reef limestone sometimes shows interbedding with the peloidal grainstone lithofacies. Figure 3: Lithofacies of Hanifa Formation: (**A**) Massive carbonate mudstone with scattered monaxon  
sponge spicules and agglutinated foraminiferaifera (_Kurnubia pallastineinsis_). (**B**) Wackestone facies composed of monaxon and triaxon sponge spiculitic wackestone. Associating biocomponents are echinoderm spines (**E**), and agglutinated foraminifera (**F**), and scattered fragments of sponge spicules (**S**). (**C**) Packstone lithofacies dominated by skeletal grains (mainly bivalves), sub-rounded poorly-sorted quartz grains and fine peloids. (**D**) Granstone lithofacies composed of peloids with scattered quartz grains, cortoids, and grapestones. (**E**) Polished slab of a highly cemented scleractinian coral head, which is the main reef builder in the studied succession. (**F**) Oncoidal rudstone beds associating the reef limestone.