Salil Fm
Type Locality and Naming
The Salil Formation represents the slope facies of a rapidly prograding carbonate system that transgressed the Arabian Plate in the Early Cretaceous. Type section is southeast Al Jabal Al Akhdar, alongside the road to the Saiq Plateau (E57°41 ́30”, N23°02 ́00”). Additional reference section is Dhulaima-4. Column: Oman Subsurface, Oman Outcrop
Synonym:
Lithology and Thickness
A sequence of alternating thin limestones, argillaceous limestones and marls. The upper surfaces of some limestone beds are reddened. Limestone beds may show evidence of graded bedding. Sequence stratigraphy: Sharland et al. (2001) correlate their MFS K30 and K20 surfaces into the Salil Formation.
Relationships and Distribution
Lower contact
Regionally, the Fm is transitional onto the underlying Rayda Fm.
Upper contact
The upper boundary is picked at the base of a continuous clean carbonate, shown in the subsurface by Gamma-ray log character and in outcrop as the base of a massive weathering cliff, which forms the overlying Habshan Fm.
Regional extent
The best development of the Salil Fm and Rayda Fm is in western North Oman in the Lekhwair and adjacent areas. The Salil Formation occurs over the same area as the Rayda Formation, but tends to overstep it to the southeast, reflecting the progradational nature of the Lower Kahmah succession. Absent south of approximately 22°N. In the Al Huwaisah area the presence of the Rayda Fm is questionable; the entire sequence is here assigned to the Salil and consists of limestone with lesser amounts of dolomite and marl.
GeoJSON
Fossils
"Biozone F53 (lower part) and F52 (to ?F51). Biozone F52 can be subdivided into Early Valanginian Sub-biozone F527 (Calpionellites darderi and significant numbers of tintinnids) and Late Berriasian Sub-biozone F523 (common small Calpionella alpina). Simmons (1994) again highlights the difficulty in calibrating this part of the Lower Kahmah Group (albeit only from outcrop work in the Oman Mountains) but agrees with Sikkema (1991) in assigning a dominantly Late Berriasian – Valanginian age to the Salil Formation. Calpionellites darderi is an Early Valanginian marker species (Sharland et al., 2001), which is probably associated with the K30 MFS, placed at ca. 1,990 m in Dhulaima-4 by Sharland et al. (2001). They position the Late Berriasian K20 MFS at ca. 2,118 m in the same well. . . . Simon Petroleum Technology (1995) supports this age assignment, having recorded the nannoplankton Nannoconus steinmannii steinmannii and N. steinmannii minor, the dinocysts Perisseiasphaeridium insolitum, Tubotuberella apatela, ?Batioladinium varigranosum, Muderongia microperforata and Tehamadinium daveyi together with the microfauna (calpionellids) Calpionellites darderi, Calpionella alpina and Tintinnopsella longa."
Age
Depositional setting
"The Salil Fm represents the slope facies of a rapidly prograding carbonate system that transgressed the Arabian Plate in the Early Cretaceous. Pelagic fossils in the marls and lower limestones indicate a sub-wavebase marine setting. The upward increase of shallow water debris, partly as turbidite-like beds, corresponds to the rapid progradation of a carbonate platform slope succession, progressively shallowing upwards. The underlying Rayda Fm represents the contemporaneous deep-water equivalents, with the overlying Habshan Fm and Lekhwair Fm corresponding to respectively the platform edge and intra-platform carbonate facies (Droste and van Steenwinkel, 2004)."
Additional Information