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GROUPFORMATIONMEMBER
HadhramautDammam 
Rus 
Umm Er RadhumaUpper Umm Er Radhuma
Middle Umm Er Radhuma
Shammar
GROUPFORMATIONMEMBER
HadhramautDammam 
Rus 
Umm Er RadhumaUpper Umm Er Radhuma
Middle Umm Er Radhuma
Shammar

Authors: Wetzel and Morton (unpublished, 1948), see Beydoun and Greenwood (1968).

Introduction

The Hadhramaut Group embraces the largely carbonate sequence between the Cretaceous – Cenozoic boundary and the regional mid-Cenozoic break.

Type and reference section: South Yemen and Dhofar tablelands. Dhulaima-2 (Figures 4.2 and 4.7) is here proposed as the Omani reference well. Although Hughes Clarke (1988) proposed Biladi-1 as the reference well for all three individual formations, Dhulaima-2 has a much more complete and better quality data set, e.g. wireline logs.

Figure 4.1:

Location map: Hadhramaut Group.

Figure 4.1:

Location map: Hadhramaut Group.

Figure 4.2.

Composite electrical logs, lithology and lithological description of the Dammam and Rus formations, Hadhramaut Group, in well Dhulaima-2, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Figure 4.2.

Composite electrical logs, lithology and lithological description of the Dammam and Rus formations, Hadhramaut Group, in well Dhulaima-2, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Lithology: The sequence is punctuated by a median evaporitic phase, the Rus Formation, which separates a lower thick carbonate unit, the Umm Er Radhuma Formation, from an upper unit, the Dammam Formation, which may be dominantly carbonate, or significantly marly or shaly.

Distribution: Potentially present throughout Oman. North, in the Al Hajar Mountains, the evaporitic Rus facies is not developed and other variations occur (Nolan et al., 1986). Over the Al Huqf axis outcrop areas and eastern Central Oman, the Lower Tertiary is absent by erosion. The Umm Er Radhuma, Rus, Dammam triad has been referred to as the Hasa Group (Owen and Nasr, 1958) in northern Gulf areas. Use of the Hadhramaut Group reflects the rather wider lithological variation in Oman.

Subdivision: The Group is divided into the Dammam, Rus and Umm Er Radhuma formations.

Sequence stratigraphy: Megasequence AP10 (Sharland et al., 2001). Sharland et al. (2001) position their MFS Pg20 and MFS Pg10 surfaces within the Dammam and Umr Er Radhuma (Shammar Member), respectively. The presence of Early Palaeocene (Danian) sediments is subject to debate.

Age: Middle Palaeocene – Middle Eocene, ca. 61.1–37.2 Ma. In northern areas of Interior Oman the Dammam can include carbonates of possible Late Eocene age.

Biostratigraphy:Al Zedjaly (1998) documents the Tertiary Micropalaeontological zonation applied to the Group. However, some of the original work dates back to the 1960s, and the zonation is almost certainly in much need of revision. In particular the implied Late Eocene and Early Palaeocene ages need to be further investigated. Biozones F76 to F71 can be summarised as follows:

ZoneSubzoneMarker speciesRelative ageFormation/Member
F76 Nummulites fabianii/Pellatispira madarasziLate EoceneDammam
F75 Nummulites bayhariensis/Dictyoconus indicus Nummulites discorbinusMiddle Eocene
Unzoned No microfossilsEarly? EoceneRus
F74F743Lockhartia hunti pustulosaEarly EoceneUpper Umm Er Radhuma
F742Lockhartia tipperi
F741Rotalia trochidiformis/Sakesaria cotteri
F73F733Nummulites globulus
F732Heterostegina sp.1
F731Alveolina globosa
F72 Dictyokathina simplex/Sakesaria dukhaniLate PalaeoceneMiddle Umm Er Radhuma
F71F712Miscellanea meandrina/Lockhartia haimaiEarly Palaeocene
F711Daviesina langhami/Lockhartia conditiShammar
ZoneSubzoneMarker speciesRelative ageFormation/Member
F76 Nummulites fabianii/Pellatispira madarasziLate EoceneDammam
F75 Nummulites bayhariensis/Dictyoconus indicus Nummulites discorbinusMiddle Eocene
Unzoned No microfossilsEarly? EoceneRus
F74F743Lockhartia hunti pustulosaEarly EoceneUpper Umm Er Radhuma
F742Lockhartia tipperi
F741Rotalia trochidiformis/Sakesaria cotteri
F73F733Nummulites globulus
F732Heterostegina sp.1
F731Alveolina globosa
F72 Dictyokathina simplex/Sakesaria dukhaniLate PalaeoceneMiddle Umm Er Radhuma
F71F712Miscellanea meandrina/Lockhartia haimaiEarly Palaeocene
F711Daviesina langhami/Lockhartia conditiShammar

Dammam Formation

Authors: Bramkamp (unpublished, 1941), see Powers (1968).

Introduction

Hughes Clarke (1988) describes an Andhur Formation as a more argillaceous, lateral facies equivalent of the Dammam Formation. However, such a unit has proved difficult to consistently pick and differentiate from the more marly Dammam Formation sections and it has never been consistently applied to the subsurface. Hence the practical definition of the Dammam is expanded below to include a more argillaceous composition.

Type and reference sections: Dammam Dome, along the Dhahran-Al’Alah road, Saudi Arabia (Powers, 1968; Weijermars, 1999). Subsurface reference sections are Dhulaima-2 and Barik-8 (Figures 4.2 and 4.6). The previous reference section in Oman was well Biladi-1 (see Hughes Clarke, 1988).

Lithology: A unit mainly of chalky limestone (Figure 4.3a), but with some variability in dolomitisation, minor marl interbeds and a basal calcareous shale unit. Locally, marl and shale content may increase.

Figure 4.3.

Ditch cuttings from the Hadhramaut Group: (a) limestone-wackestone from the Dammam Formation, from Al Huwaisah-7; (b) dolomite from the Rus Formation, from Al Huwaisah-7; (c) limestone-wackestone/packstone, Middle Umm Er Radhuma Member, from Al Huwaisah-7; and (d) shale from the Shammar Member, Umm Er Radhuma Formation, from Lekhwair-69 (scale grid is 1 x 1 mm) (Mohammed et al., 1997).

Figure 4.3.

Ditch cuttings from the Hadhramaut Group: (a) limestone-wackestone from the Dammam Formation, from Al Huwaisah-7; (b) dolomite from the Rus Formation, from Al Huwaisah-7; (c) limestone-wackestone/packstone, Middle Umm Er Radhuma Member, from Al Huwaisah-7; and (d) shale from the Shammar Member, Umm Er Radhuma Formation, from Lekhwair-69 (scale grid is 1 x 1 mm) (Mohammed et al., 1997).

Subsurface recognition: Whilst drilling, the Dammam Formation is recognised by the change to cleaner chalky limestone and the absence of dolomite, which is commonly encountered in the Fars Group. The Rate of Penetration of the Dammam is slower and more constant than that of the overlying Fars Group and underlying Rus Formation (Figure 3.5).

Boundaries: The lower contact is conformable. The upper contact is a hiatus overlain by Fars carbonates or clastics which, if fossiliferous, can give evidence of an age-gap.

Distribution: The Dammam Formation is potentially present throughout Interior Oman, except in areas of young outcrop erosion. The Qara Formation, as defined in Dhofar, is here considered as a synonym of the Dammam. The thin basal shale is found throughout North Oman where it is best developed. It is not present in South Oman. This has implications for the hydrogeology of the Formation, with better aquifer potential in the limestones than in the argillaceous limestone/marls/claystones.

Deposition: Lithologies and fossils provide evidence for a shallow-marine environment.

Age: Early–Middle Eocene age, ca. 50–37.2 Ma. Possible Late Eocene in the most northerly sequences in Interior Oman. Sharland et al. (2001) suggest a latest Ypresian (Early Eocene) age for the basal Dammam Formation, where they place their MFS Pg20 regionally.

Biostratigraphy: There is an abundance of Middle Eocene fauna - mainly the larger forams Nummulites e.g. N. fabianii, N. discorbinus, N. bayhariensis and N. beaumonti (Figures 4.4 and 4.5). Biozones F76 and F75 (see Group discussion).

Figure 4.4.

Fossils from the Dammam Formation, Middle Eocene Biozone F75: (a-c) Common and sometimes loose, Nummulites discorbinus; and (d-g) Rare to common and sometimes loose, Dictyoconus indicus (Mohammed et al., 1997).

Figure 4.4.

Fossils from the Dammam Formation, Middle Eocene Biozone F75: (a-c) Common and sometimes loose, Nummulites discorbinus; and (d-g) Rare to common and sometimes loose, Dictyoconus indicus (Mohammed et al., 1997).

Figure 4.5.

Fossils from the Dammam Formation, Middle Eocene Biozone F75: (a and b) Common and sometimes loose, Nummulites beaumonti; (c-e) Rare to common and sometimes loose, Linderina brugesi; and (f and g) Common and sometimes loose Dictyoconoides cooki var. kohaticus (Mohammed et al., 1997).

Figure 4.5.

Fossils from the Dammam Formation, Middle Eocene Biozone F75: (a and b) Common and sometimes loose, Nummulites beaumonti; (c-e) Rare to common and sometimes loose, Linderina brugesi; and (f and g) Common and sometimes loose Dictyoconoides cooki var. kohaticus (Mohammed et al., 1997).

Rus Formation

Authors: Bramkamp (unpublished, 1946), see Powers (1968).

Introduction

The Rus Formation comprises a widespread succession of evaporites and carbonates. Within the Hadhramaut Group it represents a median evaporitic phase separating the carbonates of the overlying Dammam Formation and the underlying Umm Er Radhuma Formation, one of the most important shallow aquifers in Interior Oman.

Type and reference sections: Umm Er Ru’us, Saudi Arabia (Powers, 1968; see also Weijermars, 1999). Subsurface reference sections are Dhulaima-2 (Figure 4.2) and Barik-8 (Figure 4.6). The previous reference section in Oman was well Biladi-1 (see Hughes Clarke, 1988).

Figure 4.6.

Composite electrical logs and lithological description of the Taqa and Rus formations, Hadhramaut Group, in well Barik-8, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Figure 4.6.

Composite electrical logs and lithological description of the Taqa and Rus formations, Hadhramaut Group, in well Barik-8, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Lithology: Dominantly evaporite, gypsum or anhydrite, with associated variable dolomite and dolomitic marl (Figure 4.3b). Silica geodes and secondary silicification are common in South Oman.

Subsurface recognition: Whilst drilling the top of the Rus is marked by the first appearance of dolomite. It has a characteristic thick anhydrite (gypsum) layer, generally near the base. Ditch cuttings are generally only collected below the first casing, i.e., within the Arada (?) or below the Shammar. The uppermost dolomite and basal gypsum/anhydrite are well marked by Rate of Penetration changes (positive and negative drillbreaks, respectively). The Rate of Penetration log exhibits an erratic pattern (faster in dolomites than anhydrites) (see Lekhwair-251, Figure 3.5). Post-drilling well Gamma log correlation, using expanded Gamma scale (e.g. 5–40° API) to enhance the log character (Barik-8, Figure 4.6), is recommended. The highly erratic Sonic and Density log patterns are very characteristic. The sequence is barren of age diagnostic fauna.

Boundaries: Upper and lower boundaries are conformable and transitional into the Dammam and Umm Er Radhuma carbonates.

Distribution: Occurs throughout Interior Oman, except to the southeast. The evaporitic facies defining this unit is not developed in the Batinah Coast Palaeogene, hence the Al Hajar Mountains axis may have formed a barrier.

Deposition: Generally barren of fossils suggesting deposition in a restricted lagoon, playa or sabkha setting. By its widespread occurrence, it must reflect a regional sea-level fall from a stable shelf.

Age: Early Eocene, ca. 52–50 Ma. Inferred from the age of bracketing formations.

Umm Er Radhuma Formation

Authors: Henry and Brown (unpublished, 1935), see Powers (1968).

Introduction

A succession of variably chalky wackestones/packstones, rich in larger foraminifera, with a basal grey shale - the Shammar Member (Figure 4.3c and d). The dolomitic uppermost unit and permeable zones within the middle of the Formation combine to make this the most important aquifer in Interior Oman.

Type and reference sections: Near Umm Radmah, Saudi Arabia (Powers, 1968). Subsurface reference section is in Dhulaima-2 (Figure 4.7). The previous reference section in Oman was well Biladi-1 (Hughes Clarke, 1988).

Figure 4.7.

Composite electrical logs, lithology and lithological description of the Umm Er Radhuma Formation, Hadhramaut Group, in well Dhulaima-2, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Figure 4.7.

Composite electrical logs, lithology and lithological description of the Umm Er Radhuma Formation, Hadhramaut Group, in well Dhulaima-2, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Lithology: A thick, continuous carbonate sequence with only minor argillaceous breaks, but with an important shale/marl unit forming the base, the Shammar Member (Figure 4.3d). Sandstone occurrences are known from the Middle Umm Er Radhuma in the Qarn Alam area (Osterloff and Al-Rhamah, 2001). The carbonates are slightly dolomitic limestones except for the top 15–30 m where dolomitisation can be considerable, giving sucrosic and very porous beds. The upper dolomitic unit is often, and characteristically, split by a thin anhydrite. The Middle Umm Er Radhuma limestones are often vuggy.

The vugginess of the Middle Umm Er Radhuma limestones makes this an important aquifer. The more localised basal Middle Umm Er Radhuma sandstones also represent a good aquifer. The sandstones range from fine to coarse, with common lithic grains and pyrite.

Subsurface recognition: Whilst drilling, ‘hotshot’, samples for fossil analysis may help to distinguish the lithologically similar Upper and Middle Umm Er Radhuma, where there is a sharp faunal change. ‘Near top Umm Er Radhuma’ is identified by the change from dolomites to chalky fossiliferous limestones. The upper boundary (Rus-Umm Er Radhuma) is marked by a positive drillbreak (see Lekhwair-251, Figure 3.5). The Umm Er Radhuma has a slightly higher and more constant Rate of Penetration than the overlying interbedded evaporitic Rus Formation.

Often, there is a positive drillbreak at the Upper/Middle boundary in Central and South Oman (in North Oman the top of the Middle Umm Er Radhuma may be a hard argillaceous limestone and the drill break is not so evident); there is often also a marked reduction in Rate of Penetration approximately two-thirds through the Middle Umm Er Radhuma.

In South Oman the Middle Umm Er Radhuma is often drilled with ‘no returns’. Total losses occur a few metres below the top. The limestones are pale yellow brown (Figure 4.3c), and more vuggy and fossiliferous than the greyer, chalky Natih and the frequently argillaceous Arada limestones.

The Shammar Shales are grey only and differ in this aspect from the often underlying varicoloured shales of the Nahr Umr and Natih. It is impossible to distinguish the Shammar shales from the undifferentiated Aruma shales of South Oman and the Shargi shales of North Oman (see also Fiqa Formation). The upper and lower boundaries of the Shammar Shale are marked by negative and positive drill breaks, respectively. The Shammar has recognisable plant remains in South and Central Oman. Post-drilling the upper boundary is picked on log character, i.e., increase in Gamma, decrease in Density. Biostratigraphic analysis can confirm several biozones corresponding to the various members. Log correlation - expanded Gamma log scale (e.g. 5–40° API) is required when logged through casing.

Boundaries: The lower boundary is a hiatus or disconformity. Where the Shammar shales lie upon Fiqa shales recognition of the boundary may require age determination by fossils, which is also the case where the Shammar is absent, e.g. to the east, and the unit overlies older carbonates. The upper boundary is conformable and transitional into the marls and evaporites of the Rus.

The boundary between the Rus and the Umm Er Radhuma formations is impossible to distinguish on lithology as the upper few metres of the Umm Er Radhuma are dolomites similar to the Rus. Postdrilling, it can be placed at the base of the deepest significant anhydrite bed in the Rus.

Distribution: The Umm Er Radhuma Formation is a relatively uniform and widespread unit throughout Interior Oman, but is cut out beneath the Fars to the southeast. Correlation shows a thickening in all units from southeast to northwest. No differences in the Umm Er Radhuma occurs between North, Central and South Oman with the exception of the development of the Shammar. The Shammar is thinner in South and Central Oman and interbedded with thin limestones only in North Oman.

Deposition: Common marine fossils indicate a shallow-marine environment, probably intertidal in part.

Subdivision: Subdivided into Upper, Middle and Lower (Shammar Member, informally referred to as the Shammar Shale).

Age: Middle Palaeocene – Early Eocene age, ca. 61.1–52 Ma. Sharland et al. (2001) place their MFS Pg10 within the Shammar Member in Oman (well Biladi-1). Regionally they date this MFS as Late Palaeocene, which is at odds with the Early Palaeocene age suggested by Al Zedjaly (1998) for the Shammar Member. A Middle Palaeocene age is proposed herein until further study proves otherwise. An absence of Late Maastrichtian – Danian (Early Palaeocene) sediments across much of the Arabian Plate is noted by Sharland et al. (2001).

Biostratigraphy: Biozones F74 (3 subzones), F73 (3 subzones), F72 and F71 (2 subzones) (see Group discussion, Figures 4.8 to 4.12). The Early Palaeocene (Danian) age of Biozone F71 requires confirmation.

Figure 4.8.

Fossils from the Upper Umm Er Radhuma Member: (a-c) Common and sometimes loose, Rotalia trochidiformis from the Lower Eocene Sub-biozone F741; (d) Rare and sometimes loose, Alveolina globosa from the Lower Eocene Sub-biozone F731; (e and f) Common and sometimes loose, Nummulites globulus from the Lower Eocene Sub-biozone F733; and (g) Common and sometimes loose, Heterostegina sp. from the Lower Eocene Sub-biozone F732 (Mohammed et al., 1997).

Figure 4.8.

Fossils from the Upper Umm Er Radhuma Member: (a-c) Common and sometimes loose, Rotalia trochidiformis from the Lower Eocene Sub-biozone F741; (d) Rare and sometimes loose, Alveolina globosa from the Lower Eocene Sub-biozone F731; (e and f) Common and sometimes loose, Nummulites globulus from the Lower Eocene Sub-biozone F733; and (g) Common and sometimes loose, Heterostegina sp. from the Lower Eocene Sub-biozone F732 (Mohammed et al., 1997).

Figure 4.9.

Fossils from the Upper Umm Er Radhuma Member: (a and b) Common and sometimes loose, Lockhartia hunti pustulosa from the Lower Eocene Sub-biozone F743; (c and d) Common and sometimes loose, Lockhartia tipperi from the Lower Eocene Sub-biozone F742; and (e and f) Common and sometimes loose, Sakesaria cotteri from the Lower Eocene Sub-biozone F741 (Mohammed et al., 1997).

Figure 4.9.

Fossils from the Upper Umm Er Radhuma Member: (a and b) Common and sometimes loose, Lockhartia hunti pustulosa from the Lower Eocene Sub-biozone F743; (c and d) Common and sometimes loose, Lockhartia tipperi from the Lower Eocene Sub-biozone F742; and (e and f) Common and sometimes loose, Sakesaria cotteri from the Lower Eocene Sub-biozone F741 (Mohammed et al., 1997).

Figure 4.10.

Fossils from the Middle Umm Er Radhuma Member, Upper Palaeocene Biozone F72: (a and b) Common and sometimes loose, Dictyokathina simplex; (c and d) Common and sometimes loose, Miscellanea miscella; (e) Rare and sometimes loose, Sakesaria dukhani; and (f and g) Common and sometimes loose, Kathina major (Mohammed et al., 1997).

Figure 4.10.

Fossils from the Middle Umm Er Radhuma Member, Upper Palaeocene Biozone F72: (a and b) Common and sometimes loose, Dictyokathina simplex; (c and d) Common and sometimes loose, Miscellanea miscella; (e) Rare and sometimes loose, Sakesaria dukhani; and (f and g) Common and sometimes loose, Kathina major (Mohammed et al., 1997).

Figure 4.11.

Fossils from the Middle Umm Er Radhuma Member, Lower Palaeocene Sub-biozone F711: (a-e) Common and sometimes loose, Daviesina khatiyahi; and (f and g) Rare, common and sometimes loose, Lockhartia conditi (Mohammed et al., 1997).

Figure 4.11.

Fossils from the Middle Umm Er Radhuma Member, Lower Palaeocene Sub-biozone F711: (a-e) Common and sometimes loose, Daviesina khatiyahi; and (f and g) Rare, common and sometimes loose, Lockhartia conditi (Mohammed et al., 1997).

Figure 4.12.

Fossils from the Middle Umm Er Radhuma Member, Lower Palaeocene Sub-biozone F712: (a and b) Rare and sometimes loose, Miscellanea meandrina; and (c-g) Common, abundant and sometimes loose, Lockhartia haimai (Mohammed et al., 1997).

Figure 4.12.

Fossils from the Middle Umm Er Radhuma Member, Lower Palaeocene Sub-biozone F712: (a and b) Rare and sometimes loose, Miscellanea meandrina; and (c-g) Common, abundant and sometimes loose, Lockhartia haimai (Mohammed et al., 1997).

Figures & Tables

Figure 4.1:

Location map: Hadhramaut Group.

Figure 4.1:

Location map: Hadhramaut Group.

Figure 4.2.

Composite electrical logs, lithology and lithological description of the Dammam and Rus formations, Hadhramaut Group, in well Dhulaima-2, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Figure 4.2.

Composite electrical logs, lithology and lithological description of the Dammam and Rus formations, Hadhramaut Group, in well Dhulaima-2, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Figure 4.3.

Ditch cuttings from the Hadhramaut Group: (a) limestone-wackestone from the Dammam Formation, from Al Huwaisah-7; (b) dolomite from the Rus Formation, from Al Huwaisah-7; (c) limestone-wackestone/packstone, Middle Umm Er Radhuma Member, from Al Huwaisah-7; and (d) shale from the Shammar Member, Umm Er Radhuma Formation, from Lekhwair-69 (scale grid is 1 x 1 mm) (Mohammed et al., 1997).

Figure 4.3.

Ditch cuttings from the Hadhramaut Group: (a) limestone-wackestone from the Dammam Formation, from Al Huwaisah-7; (b) dolomite from the Rus Formation, from Al Huwaisah-7; (c) limestone-wackestone/packstone, Middle Umm Er Radhuma Member, from Al Huwaisah-7; and (d) shale from the Shammar Member, Umm Er Radhuma Formation, from Lekhwair-69 (scale grid is 1 x 1 mm) (Mohammed et al., 1997).

Figure 4.4.

Fossils from the Dammam Formation, Middle Eocene Biozone F75: (a-c) Common and sometimes loose, Nummulites discorbinus; and (d-g) Rare to common and sometimes loose, Dictyoconus indicus (Mohammed et al., 1997).

Figure 4.4.

Fossils from the Dammam Formation, Middle Eocene Biozone F75: (a-c) Common and sometimes loose, Nummulites discorbinus; and (d-g) Rare to common and sometimes loose, Dictyoconus indicus (Mohammed et al., 1997).

Figure 4.5.

Fossils from the Dammam Formation, Middle Eocene Biozone F75: (a and b) Common and sometimes loose, Nummulites beaumonti; (c-e) Rare to common and sometimes loose, Linderina brugesi; and (f and g) Common and sometimes loose Dictyoconoides cooki var. kohaticus (Mohammed et al., 1997).

Figure 4.5.

Fossils from the Dammam Formation, Middle Eocene Biozone F75: (a and b) Common and sometimes loose, Nummulites beaumonti; (c-e) Rare to common and sometimes loose, Linderina brugesi; and (f and g) Common and sometimes loose Dictyoconoides cooki var. kohaticus (Mohammed et al., 1997).

Figure 4.6.

Composite electrical logs and lithological description of the Taqa and Rus formations, Hadhramaut Group, in well Barik-8, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Figure 4.6.

Composite electrical logs and lithological description of the Taqa and Rus formations, Hadhramaut Group, in well Barik-8, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Figure 4.7.

Composite electrical logs, lithology and lithological description of the Umm Er Radhuma Formation, Hadhramaut Group, in well Dhulaima-2, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Figure 4.7.

Composite electrical logs, lithology and lithological description of the Umm Er Radhuma Formation, Hadhramaut Group, in well Dhulaima-2, North Oman (Mohammed et al., 1997). See Figure 4.1 for location.

Figure 4.8.

Fossils from the Upper Umm Er Radhuma Member: (a-c) Common and sometimes loose, Rotalia trochidiformis from the Lower Eocene Sub-biozone F741; (d) Rare and sometimes loose, Alveolina globosa from the Lower Eocene Sub-biozone F731; (e and f) Common and sometimes loose, Nummulites globulus from the Lower Eocene Sub-biozone F733; and (g) Common and sometimes loose, Heterostegina sp. from the Lower Eocene Sub-biozone F732 (Mohammed et al., 1997).

Figure 4.8.

Fossils from the Upper Umm Er Radhuma Member: (a-c) Common and sometimes loose, Rotalia trochidiformis from the Lower Eocene Sub-biozone F741; (d) Rare and sometimes loose, Alveolina globosa from the Lower Eocene Sub-biozone F731; (e and f) Common and sometimes loose, Nummulites globulus from the Lower Eocene Sub-biozone F733; and (g) Common and sometimes loose, Heterostegina sp. from the Lower Eocene Sub-biozone F732 (Mohammed et al., 1997).

Figure 4.9.

Fossils from the Upper Umm Er Radhuma Member: (a and b) Common and sometimes loose, Lockhartia hunti pustulosa from the Lower Eocene Sub-biozone F743; (c and d) Common and sometimes loose, Lockhartia tipperi from the Lower Eocene Sub-biozone F742; and (e and f) Common and sometimes loose, Sakesaria cotteri from the Lower Eocene Sub-biozone F741 (Mohammed et al., 1997).

Figure 4.9.

Fossils from the Upper Umm Er Radhuma Member: (a and b) Common and sometimes loose, Lockhartia hunti pustulosa from the Lower Eocene Sub-biozone F743; (c and d) Common and sometimes loose, Lockhartia tipperi from the Lower Eocene Sub-biozone F742; and (e and f) Common and sometimes loose, Sakesaria cotteri from the Lower Eocene Sub-biozone F741 (Mohammed et al., 1997).

Figure 4.10.

Fossils from the Middle Umm Er Radhuma Member, Upper Palaeocene Biozone F72: (a and b) Common and sometimes loose, Dictyokathina simplex; (c and d) Common and sometimes loose, Miscellanea miscella; (e) Rare and sometimes loose, Sakesaria dukhani; and (f and g) Common and sometimes loose, Kathina major (Mohammed et al., 1997).

Figure 4.10.

Fossils from the Middle Umm Er Radhuma Member, Upper Palaeocene Biozone F72: (a and b) Common and sometimes loose, Dictyokathina simplex; (c and d) Common and sometimes loose, Miscellanea miscella; (e) Rare and sometimes loose, Sakesaria dukhani; and (f and g) Common and sometimes loose, Kathina major (Mohammed et al., 1997).

Figure 4.11.

Fossils from the Middle Umm Er Radhuma Member, Lower Palaeocene Sub-biozone F711: (a-e) Common and sometimes loose, Daviesina khatiyahi; and (f and g) Rare, common and sometimes loose, Lockhartia conditi (Mohammed et al., 1997).

Figure 4.11.

Fossils from the Middle Umm Er Radhuma Member, Lower Palaeocene Sub-biozone F711: (a-e) Common and sometimes loose, Daviesina khatiyahi; and (f and g) Rare, common and sometimes loose, Lockhartia conditi (Mohammed et al., 1997).

Figure 4.12.

Fossils from the Middle Umm Er Radhuma Member, Lower Palaeocene Sub-biozone F712: (a and b) Rare and sometimes loose, Miscellanea meandrina; and (c-g) Common, abundant and sometimes loose, Lockhartia haimai (Mohammed et al., 1997).

Figure 4.12.

Fossils from the Middle Umm Er Radhuma Member, Lower Palaeocene Sub-biozone F712: (a and b) Rare and sometimes loose, Miscellanea meandrina; and (c-g) Common, abundant and sometimes loose, Lockhartia haimai (Mohammed et al., 1997).

GROUPFORMATIONMEMBER
HadhramautDammam 
Rus 
Umm Er RadhumaUpper Umm Er Radhuma
Middle Umm Er Radhuma
Shammar
GROUPFORMATIONMEMBER
HadhramautDammam 
Rus 
Umm Er RadhumaUpper Umm Er Radhuma
Middle Umm Er Radhuma
Shammar
ZoneSubzoneMarker speciesRelative ageFormation/Member
F76 Nummulites fabianii/Pellatispira madarasziLate EoceneDammam
F75 Nummulites bayhariensis/Dictyoconus indicus Nummulites discorbinusMiddle Eocene
Unzoned No microfossilsEarly? EoceneRus
F74F743Lockhartia hunti pustulosaEarly EoceneUpper Umm Er Radhuma
F742Lockhartia tipperi
F741Rotalia trochidiformis/Sakesaria cotteri
F73F733Nummulites globulus
F732Heterostegina sp.1
F731Alveolina globosa
F72 Dictyokathina simplex/Sakesaria dukhaniLate PalaeoceneMiddle Umm Er Radhuma
F71F712Miscellanea meandrina/Lockhartia haimaiEarly Palaeocene
F711Daviesina langhami/Lockhartia conditiShammar
ZoneSubzoneMarker speciesRelative ageFormation/Member
F76 Nummulites fabianii/Pellatispira madarasziLate EoceneDammam
F75 Nummulites bayhariensis/Dictyoconus indicus Nummulites discorbinusMiddle Eocene
Unzoned No microfossilsEarly? EoceneRus
F74F743Lockhartia hunti pustulosaEarly EoceneUpper Umm Er Radhuma
F742Lockhartia tipperi
F741Rotalia trochidiformis/Sakesaria cotteri
F73F733Nummulites globulus
F732Heterostegina sp.1
F731Alveolina globosa
F72 Dictyokathina simplex/Sakesaria dukhaniLate PalaeoceneMiddle Umm Er Radhuma
F71F712Miscellanea meandrina/Lockhartia haimaiEarly Palaeocene
F711Daviesina langhami/Lockhartia conditiShammar

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