Dhulaima Fm

Period:

Neogene

Age Interval:

Latest Oligocene – Pliocene, On1

Province:
Oman

Type Locality and Naming

Proposed by Forbes et al. (2010 – see reference in "Compiler" below). Type section: Dhulaia-1 well. Column: Oman Subsurface; Uppermost formation in Fars Gr

Synonym: Clastics and Evaporites Fm (usage by Petroleum Development Oman and by Hughes Clarke, 1988). Synonymous with Fars Gr in North Oman, because this facies extends to the base of the Fars Gr.

Lithology and Thickness

Dolomite. "The Dhulaima Formation is an undifferentiated sequence of interbedded dolomites, rarer limestones, shales, gypsum and anhydrites.. . . dominated by calcareous dolomites and evaporites with bioclastic and often argillaceous limestone and calcareous shale towards the base. The dolomites are rich in gastropods and lamellibranchs. Lithologically, the dolomites and evaporites do not differ from those of the Rus Fm."

Lithology Pattern:

Dolomite

Relationships and Distribution

Lower contact

Regionally, the schematic single generalized strat column for indicates the next older unit as Taqa Fm. However, the Taqa Fm is essentially coeval and is dominate in South and Central Oman. In boreholes, "the basal part is picked mainly for F77 (FZU) (Oligocene - marked by Nummulites intermedius,"

Upper contact

This is the uppermost formation. The top boundary is picked mainly on faunal evidence for Biozone F78 (FZV).

Regional extent

"The Dhulaima Fm occurs in northern Oman only. It is very variable laterally and intra-formational correlations are extremely difficult to carry out."

GeoJSON

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Fossils

Distinct fauna, predominantly of Miocene age (F78) with the basal part being Oligocene (Nummulites intermedius, F77). See Dhulaima Gr and Taqa Fm discussions.

Age

Langhian – Gelasian for display purposes to allow showing coeval Taqa Fm. Actual span is "Oligocene – Pliocene, ca. 33–1.8 Ma. The Oligocene calibration in northern Oman relates to the non-dolomitic sections in northwest Oman (e.g., well Dhulaima-1)"

Age Span:

Beginning stage:

Langhian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

15.99

Ending stage:

Gelasian

Fraction up in the ending stage:

1.0

Ending date (Ma):

1.80

Depositional setting

"Thought to have been deposited under mainly shallow-marine conditions with significant clastic influence."

Depositional pattern:

Additional Information

Compiler:
" below). Type section: Dhulaia-1 well. Column: Oman Subsurface; Uppermost formation in Fars Gr
Synonym: Clastics and Evaporites Fm (usage by Petroleum Development Oman and by Hughes Clarke, 1988). Synonymous with Fars Gr in North Oman, because this facies extends to the base of the Fars Gr.
Lithology and Thickness:
Dolomite. "The Dhulaima Formation is an undifferentiated sequence of interbedded dolomites, rarer limestones, shales, gypsum and anhydrites.. . . dominated by calcareous dolomites and evaporites with bioclastic and often argillaceous limestone and calcareous shale towards the base. The dolomites are rich in gastropods and lamellibranchs. Lithologically, the dolomites and evaporites do not differ from those of the Rus Fm."
Lithology-pattern: Dolomite
Relationships and Distribution:
Lower contact:
Regionally, the schematic single generalized strat column for indicates the next older unit as Taqa Fm. However, the Taqa Fm is essentially coeval and is dominate in South and Central Oman. In boreholes, "the basal part is picked mainly for F77 (FZU) (Oligocene - marked by Nummulites intermedius,"
Upper contact:
This is the uppermost formation. The top boundary is picked mainly on faunal evidence for Biozone F78 (FZV).
Regional extent:
"The Dhulaima Fm occurs in northern Oman only. It is very variable laterally and intra-formational correlations are extremely difficult to carry out."
GeoJSON: { "type": "Feature", "properties": { "id": null, "NAME": "Oman Subsurface" }, "geometry": { "type": "MultiPolygon", "coordinates": [ [ [ [ 56.61, 25.90], [56.59, 25.95], [56.42, 24.85], [57.05, 24.04], [57.72, 23.77], [58.58, 23.65], [59.12, 22.75], [59.82, 22.49], [58.59, 21.81], [57.69, 19.59], [56.82, 18.86], [56.45, 18.02], [55.52, 17.84], [54.9, 16.95], [54.31, 17.09], [53.35, 16.9], [53.71, 16.37], [55.1, 16.58], [57.6, 17.33], [58.17, 17.22], [58.18, 18.81], [60.41, 21.35], [60.22, 22.98], [56.61, 25.90] ] ] ] } }
Fossils:
Distinct fauna, predominantly of Miocene age (F78) with the basal part being Oligocene (Nummulites intermedius, F77). See Dhulaima Gr and Taqa Fm discussions.
Age:
Langhian – Gelasian for display purposes to allow showing coeval Taqa Fm. Actual span is "Oligocene – Pliocene, ca. 33–1.8 Ma. The Oligocene calibration in northern Oman relates to the non-dolomitic sections in northwest Oman (e.g., well Dhulaima-1)"
Age span:
Beginning stage: Langhian
Fraction up in beginning stage: 0.0
Beginning date (Ma):
Ending stage: Gelasian
Fraction up in ending stage: 1.0
Ending date (Ma):
Depositional setting:
"Thought to have been deposited under mainly shallow-marine conditions with significant clastic influence."
Depositional-pattern:
Additional Information
Compiler
From Forbes, G.A., Hansen, H.S.M., and Shreurs, J., 2010. Lexicon of Oman: Subsurface Stratigraphy. Gulf Petrolink, 371 pp. (plus enclosures and CD); and Middle East Geological Timescale 2008 Al-Husseini, Journal of Middle East Petroleum Geosciences v 13. no. 4