Back shoal cycle type

This cycle type has an average thickness from 6 to 8 m (Fig. 7), it exists in S1and S2 in all sections. The basal part is several decimeters thick, begins with calcareous fossiliferous, coarse grained and moderately sorted quartz arenite. Well preserved molluscan fauna and echinoids are common (LFT 2b). The facies stacking pattern is followed by up to 2 m thick units of bioclastic dolomitic wackestone that the major

components of it represented by micritized foraminiferes (Miliolidae) and dominant echinoid fragments (LFT 3b). The middle part of this cycle is represented by bioclastic echinoidal packstone which contains a high amount of echinoid, algae, bryozoa and

shell fragments (LFT 4c). The upper part of this cycle is several 146 decimeters thick,consists of gray, moderately hard and poorly sorted bioclastic wacke/packstone, with subangular to subrounded mudclasts (LFT 4a). The clastic basal part and the wackestones in the lower part of this cycle type could be interpreted as a proximal lagoon environment deposited under low energy conditions and could represent the transgressive hemi-cycle. Muddy, finely grained and prevailing echinoid beds could be interpreted as full marine distal lagoon environment

and thus, the presence of a maximum flooding zone in the middle part. The regressive hemi-cycle is interpreted to be marked by the transition from the distal lagoon to proximal lagoon in the upper part.

Shoal cycle type

This rather asymmetrical cycle type ranges in thickness from 6 to 8 m (Fig. 8).

The distribution of this cycle type is mainly observed in S2 and S3 in all sections. The

base of this cycle is dominated by several decimeters thick, gray colored, moderately

hard and poorly sorted bioclastic wacke/packstones that mostly contain polymictic

bryozoans, algae, molluscan fragments, echinoids, foraminifera (Operculina

complanata, Amphistegina sp., and Miogypsina sp..) and quartz grains (LFT 4a). These

beds are overlain by up to 3 m of bioclastic pack/grainstone (LFT 5a), dominated by

Shell fragments, foraminifera (Heterostegina sp.), algae, pelecypod fragments,

echinoidal plates and spines. Above the grainstone beds, there are bryozoans

wacke/packstones which contain different types of bryozoa, foraminifera (Operculina

complanata, Amphistegina sp. and Miliolidae), algae, molluscan fragments, echinoids,

algal oncoids and quartz grains (LFT 4b). The cycle is capped by a 169 sharp top, marked

by a bioturbated hard ground which consists of sandy wackestone.

The basal part of this cycle is represented by bioclastic wacke/packstones,

dominated by bivalvian shells and foraminifera, which may indicate the back shoal and

also could represents the transgressive hemi-cycle. The overlying shoal pack/grainstone

beds could be interpreted as a maximum flooding zone. The regressive hemi-cycle

shows the same succession of facies types like the transgressive hemi-cycle but in a

reverse order. The sharp top of this cycle may represent the sequence boundary.

Shoal margin cycle type

This cycle ranges in thickness from 5 to 8 m (Fig. 9). They show asymmetrical

patterns. The base of this cycle is dominated by several decimeters-thick sandy

fossiliferous grainstones, represented by froaminifera (Heterostegina sp. and others)

some serpulids, algae (Lithothamnium sp.), ostracods, bryozoa (Holoporella sp.),

molluscan fragments (pelecypods and gastropods), echinoidal fragments (LFT 5c). The

grainstones beds are overlain by 2-3 m thick of framestones. These beds contain huge

amounts of scleractinian corals and algae, with frequent amount of foraminifera, shell

fragments and echinoids (LFT 6a). The upper part of this cycle type is marked by sandy

algal grainstones dominated by Lithothamnium sp., foraminiferal tests and little amount

of pellets are also present (LFT 5d).

The base of this cycle is composed of fossiliferous grainstones which could be

interpreted as shoal sediments, deposited under moderate to high energy conditions,

forming a transgressive hemi-cycle. The continuous rise in sea level led to the

deposition of algal coralline framestones indicating a shoal margin facies. The coarse9

grained nature of the coralline framestones reflects high energy and could 193 be interpreted

as maximum flooding zone. A distinctive decrease in sea level is marked by decimeters

algal grainstones forming the regressive hemi-cycle in the upper part.

Medium scale cycles (Cycle sets)

These cycle sets stack of 3 cycles, form transgressive–regressive cycle sets,

some 10-25 m in thickness. Each studied section is subdivided into 3 sequences (S1, S2

and S3) which will be explained later. Each sequence contains 3 cycle sets.

Restricted ramp cycle set

This cycle set has an average thickness of 15 m and consists of 3 small scale

cycles. It is found in CS 1.1, CS 1.3 and CS 2.3 in Gabal Genefe section (Fig. 10a), CS

1.1 and CS 1.3 in Gabal Gharra (Fig. 10b) and CS 1.1 and CS 2.1 in Gabal Homeira

 (Fig. 10c). This cycle set consists of a vertical stacking of peritidal to tidal flat small

scale cycles. In the lower part, the tidal flat sediments have an average thickness of 5 m

and decrease upward to a thickness of 2 m. In contrast, the upper part of the peritidal

beds is of greater thickness.

The lower part is interpreted as tidal flat deposits forming a transgressive hemicycle

while the upper part that consists mainly of unfossiliferous claystone indicates a

shift towards a proximal supratidal setting and forms a regressive hemi-cycle set.

Back shoal to restricted ramp cycle set

It consists of a stack of up to 3 small scale cycles, ranges in thickness from

15 to 20 m. This cycle set type is identified in CS 2.1, CS 3.1 and 3.2 at the Gabal

Genefe section (Fig. 10a). and CS 1.3, CS 2.3, CS 3.1 and CS 3.3 in Gabal Homeira

 (Fig. 10c). The lower part of this cycle set is about 12 m thick, which consists of

yellowish brown to brown, compact, massive, argillaceous, fossiliferous,

wacke/packestones, slightly ferruginous in the upper part. It contains echinoidal,

molluscan and bryozoan fragments. The microfossils include algal fragments as

Lithothamnium sp. and Lithophyllum sp.; foraminifers as Operculina complanata

 (Defrance), Miogypsina intermedia Drooger and Amphistegina sp. The beds grade

upwards to brownish yellow and yellow bioclastic packstones and they contain a

pectinids band, very crowded with Pecten beudanti Basterot, P. (Amussiopecten)

burdigalensis Lamarck. These beds also yield Gastrana sp.; gastropods, crustacea as

Balanus; bryozoa and algae. The upper part of this cycle set, up to 8 m thick, consists

of dark brown and yellowish brown; moderately compact; laminated; gypsiferous;

ferruginous; rare fossiliferous; very slightly calcareous silty claystones and sandstones.

The wacke/packstones in the lower part can be interpreted as an initial

transgression within this cycle set. During sea level rise, the distal lagoon related facies

types are interpreted as retrogradingn over the proximal lagoon deposits and may

represent a maximum flooding zone. The regressive hemi-cycle is interpreted to be

marked by the transition from the distal lagoon to the restricted ramp in the upper part.

 Shoal to back shoal cycle set

This cycle set has an average vertical thickness of 18 m and consists of 3 small scale cycles

that are identified in CS 1.2, CS 2.2 and CS 3.2 in Gabal Genefe section

 (Fig. 10a), CS 1.2, CS 2.3, CS 3.1 and CS 3.2 in Gabal Gharra (Fig. 10b) and CS 1.2,

CS 2.2 and CS 3.2 in Gabal Homeira (Fig. 10c). The basal part of this cycle set ranges

in thickness from 4 to 6 m and consists of yellowish white to 241 yellowish brown;

moderately compact sandy bioclastic wackestones, pebbly at its lower part. It is poorly

fossiliferous, and contain some bad preserved bivalvia, Balanus concavus (Bronn.) and

echinoid fragments. The basal part is overlain by 5 m of yellowish brown to light

brown; soft to moderately compact; slightly argillaceous bioclastic grainstones that are

rich with bivalves, gastropods, algae and foraminifers. The upper part is up to 6 m

thick, which consists mainly of sandy bioclastic wacke/packstones which contain

hunge amount of bivalvian shells as Pecten sp. and Chlamys sp., echinoides,

froaminiferas and algae. This cycle set is capped by thin bedded gypsiferous,

ferruginous, unfossiliferous and very slightly calcareous silty claystone.

The wackestones in the lower part could be interpreted as an initial

transgression. The continuous rise in sea level led to the deposition of distal moderate

to high energy bioclastic grainstones indicating a shoal facies, and could be interpreted

as a maximum flooding zone. The upper part consists of muddy facies which exhibits a

depositional shift toward back shoal settings during the fall of sea-level. The

claystones on the top of this cycle set suggest a low accommodation restricted ramp

environment and a sequence boundary.

Shoal margin to shoal cycle set

It consists of a stack of up to 3 small scale cycles and ranges in thickness from

15 to 20 m. This cycle set type was observed only at the Gabal Gharra section and is

identified in CS 2.1, CS 2.2 and CS 3.2 (Fig. 10b). The basal part, up to 2 m thick,

consists of yellow to yellowish white, compact, massive, slightly sandy bioclastic

grainstones. They are croweded with bivalves, gastropods, echinoderms and

foraminifera. Overlying the basal part, brown to yellow, moderately 265 hard, massive and

grain supported algal coralline framestnoes dominted by scleractinian reef which is

monospecific (Leptastrea sp.), and it is replaced in parts with algal limestone band.

The upper part of this cycle set has a range in thickness of 5 to 6 m, and is composed

of yellowish white, moderately compact, chalky bioclastic algal grainstones

domintated by algae Lithothamnium sp. and Lithophyllum sp., echinoids, bryozoans

and few coral fragments are also recorded.

The transgressive hemi-cycle resulted in the deposition of bioclastic grainstone

beds. The maximum flooding zone is built up of algal coralline framestones interpreted

as a shoal margin environment. The upper beds of this cycle set exhibit a shift from the

shoal margin towards the shoal settings representing a regressive hemi-cycle.

 Large scale cycles (sequences)

Three large scale cycles (sequences) are distinguished in the studied sections.

Sequence 1 ranges in thickness from 45 to 65 m, and it constitutes 3 medium scale

cycles and 9 small scale cycles. The base of this sequence is unexposed and its age is

interpreted to correspond to the Late Burdigalian stage (18-16.38 M.y.), according to

Snedden and Cheagjie Liu, (2010). Sequence 2 ranges in thickness between 20 and 40

m and is constituted of 3 cycle sets and 9 cycles. It matches the Langhian of the lower

part of the Genefe formation. The base of this sequence is the boundary between

Burdigalian and Langhian age. The age of S2 is interpreted to correspond to Late

Burdigalian-Early Langhian stage (16.38-14.78 M.y.). Sequence 3 ranges in thickness

between 18 and 47 m and constitutes of 3 cycle sets and 9 cycles. S3 is matches the

Serravalain of the upper part of the Genefe formation. The base of this sequence is the

boundary between Langhian and Serravallian age. The age of S3 289 is interpreted to

correspond to and Late Langhain–Early Serravallian stage (14.78-13.66 M.y.).

Gabal Genefe Section

Sequence 1

Sequence 1 is 65 m thick (Fig. 10a) and it starts with 25 m of yellowish gray;

moderately compact; thinly laminated, jointed, unfossiliferous, ferruginous,

gypsiferous shale, with gypsum bands and veins; very slightly calcareous, dipping to

the West (20-30 deg.); intercalated with yellowish brown, subrounded to subangular,

moderately sorted, semi-friable to moderately compact siltstones with shell fragments

of bivalves overlain by 25 m of brownish white, compact, massive, jointed, slightly

argillaceous sandy pack/grianstnes. They are highly fossiliferous yielding many fossil

species, including bivalvia as Crassostrea frondosa (De Serres), Alectryonella

plicatula (Gmelin), Chlamys gentoni Fontannes; gastropod molds; echinoids as

Echinolampas amplus Fuchs, Clypeaster sp., Scutella sp.; numerous Balanus concavus

 (Bronn.); red algae as Lithothamnium sp.; small coral heads, sometimes dissolved and

leaving only their molds. The main foraminiferal species in this bed are Operculina

sp., Amphistegina sp. and Heterostegina sp. The upper part of this sequence is about

15 m and consists mainly of brown, moderately compact, laminated, gypsiferous,

ferruginous, unfossiliferous, very slightly calcareous marl.

The shale beds in the lower part of the sequence 1 indicate a restricted ramp

related facies and could be interpreted as an initial transgressive hemisequence. During

the sea level rise, the change from proximal shale beds to distal carbonate beds

occurred. The maximum flooding interval could be represented on the grainstones

beds. The upper part, which is interpreted as a regressive hemisequence 313 consists of

muddy facies and might indicate a depositional shift toward the restricted ramp faceis

again during a sea-level fall.

Sequence 2

Sequence 2 is 20 m thick (Fig. 10b). The lower 12 m consists mainly of

yellowish white compact, fine to medium, subangular to rounded, moderately sorted

dolomitic quartz arenite. It is sometimes associated with grains of ferruginous materials

and poorly fossiliferous with some molluscan fragments. On top of the sandstones there

is grayish white, moderately compact bioclastic sandy pack/grainstones. The sand

content is made up of fine to medium, subangular to subrounded quartz grains,. It yields

Chlamys radians (Nyst), Ch. (Ch.) costai (Fontannes), Ch. (Argopecten) macrotis

 (Sowerby), Pecten (P.) cristato-costatus Sacco, P. (P.) fraasi Fuchs, Crassostrea frondosa (De Serres),

Natica sp., Ampullina (Pseudamaura) macfaydeni Abbass,Retepora sp., Holoporella sp., Amphistegina sp.,

Miogypsina intermedia Drooger,Operculina sp. The upper part of this sequence is about 8 m thick and

consists of greenish gray, soft to moderately compact, highly gypsiferous, ferruginous,

unfossiliferous silty claystones. The clastic beds in the lower part of the sequence 2 indicate a restricted rampto

back shoal related facies and could be interpreted as an initial transgressive hemisequence.

During the sea level rise, the distal moderate energy shoal related facies types retrograded over the clastic beds and can be interpreted as maximum flooding zone. The upper part of this sequence could represent a regressive hemicycle. It

consists of muddy facies which indicates a depositional shift towards 336 a restricted ramp setting.

 Sequence 3

The average thickness of Sequence 3 is 3 to 18 m (Fig. 10a). The lower part is

10m thick and is dominated by yellowish brown to brown, compact, massive,

argillaceous, fossiliferous bioclastic wacke/packstones, slightly ferruginous in the

upper part. These contain Chlamys (Macrochlamis) sardoa Ugolini, Clypeaster

intermedius Desmoulins, Lithothamnium sp., Lithophyllum sp., Operculina

complanata (Defrance), Miogypsina intermedia Drooger, Amphistegina sp. Above the

bioclastic packstones, thick-bedded bioclastic grainstones beds are dominated by large

sized pectinids as Pecten (Oppenheimopecten) convexo-costatus Abich, Chlamys

 (Macrochlamis) sardoa Ugolini and other molluscs, echinodermes, bryozoans and

foraminifers as Gastrana sp., Conus (Lithoconus) mercati Brocchi, Ampullina

 (Pseudamaura) maedai Abbass, Echinolampas amplus Fuchs, Clypeaster marginatus

Lamarck, Holoprella sp., Operculina complanata (Defrance), Miogypsina intermedia

Drooger, Amphistegina sp. The thickness of the upper part is about 8 m, consisting of

yellow to yellowish brown, moderately compact, bioclastic wacke/packstones. It yields

bivalves and foraminiferas as Crassostrea frondosa (De Serres), and Alectryonella

plicatula (Gmelin), Miogypsina intermedia Drooger. The uppermost part of this

sequence is represented by 0.5 m of unfossiliferous gypsiferous claystones.

The lower part of this sequence could be interpreted as back shoal proximal

sediments deposited under low energy conditions, forming a transgressive

hemisequence. The continuous rise in sea level led to the deposition of moderate

energy shoal related facies and could be interpreted as maximum 360 flooding zone. The

regressive hemisequence is interpreted to mark the transition from the distal shoal to

the proximal back shoal environment.

Gabal Gharra Section

Sequence 1

Sequence 1 of Gharra section has an average thickness of 65 m (Fig. 10b). The

lower part with a thickness of about 35 m, starting with clastic sediments of

sandstones, reddish brown; moderately compact to semi-friable; fine to medium quartz

grains; subangular to subrounded; moderately sorted; unfossiliferous and reddish

brown at the base, gray upwards; soft at bottom, firm upwards; sandy; silty claystones;

very slightly calcareous, unfossiliferous, overlianed by a ferruginous hard sandstone

band of 5 cm thickness. Above the clastic beds, there are yellowish white, moderately

compact, slightly argillaceous, bioclastic sandy pack/grainstones. The biocalstics are

represented by Crassostrea frondosa (De Serres), Alectryonella plicatula (Gmelin),

Chlamys gentoni Fontannes, Natica cf. millepunctata Lamarck, Scutella ammonis

Fuchs, Parascutella stefaninii (Desio), Prionocidaris cf. avenionensis (Desmoulins),

Echinolampas sp., Clypeaster sp. and echinoid spines and bryozoan fragments. The

upper 30 m are dominated by dark gray to gray, soft to moderately compact,

gypsiferous, unfossiliferous sandy shale, interbedded with ferruginous bands of 5 cm

thick for each. These bands increase in number upwards. Sand grains are fine and

subrounded quartz grains.

The lower part of sequence 1 consists mainly of clastic sediments which

indicates that restricted ramp deposition under low energy conditions and could

represent a transgressive hemi-sequence. These beds are arranged in 384 deepening upward

cycle sets of an open marine environment, while the maximum flooding interval could

be placed on the shoal beds. Falling sea level is interpreted by the transition from the

distal open marine to proximal restricted ramp environment again in the upper part.

Sequence 2

The average thickness of sequence 2 of the Gharra section is about 38 m (Fig.

10b). Its lower part, 20 m thick, consists of bioclastic calcareous sandstones and

fossiliferous pack/grainstones. The sandstones contain Crassostrea frondosa (De

Serres), Alectryonella plicatula (Gmelin), Chlamys scabrella Lamarck, Pecten

 (Flabellipecten) flabelliformis (Brocchi), Anomia burdigalensis Defrance, Clementia

sp., Parascutella stefaninii (Desio). The pack/grainstones beds contain Crassostrea

frondosa (De Serres), Alectryonella plicatula (Gmelin), Pecten (P.) cristato-costatus

Sacco, Chlamys scabrella Lamarck, Ch. (Argopecten) macrotis (Sowerby), Ch.

senatoria (Gmelin), Cardium sp., Callista (Costacallista) erycina (Linné), Paphia

 (Callistotapes) vetula (Bastrot), Clementia sp., Diplodonta sp., Gari sp., Lutraria sp.,

Gastrana laminosa (Sowerby), Turritella (T.) terebralis Lamarck, Echinolampas

amplus Fuchs, Clypeaster marginatus Lamarck, Scutella ammonis Fuchs, Balanus

concavus (Bronn), Lithothamnium sp., Lithophyllum sp.

On top of these beds, there are algal coralline framestones that contain high

amounts of a scleractinian coral Leptastrea sp., and it is replaced in parts with an algal

grainstone bands. The upper part of this sequence is 18 m thick consisting of yellowish

white, compact, massive, slightly argillaceous, and slightly sandy bioclastoc algal

pack/grainstones. The algae are represented by Lithothamnium sp. and Lithophyllum

sp. This sequence is capped by 1 m thick bioturbated wakestone beds, 408 which exhibit a

sharp contact. The wackestones partially display intense ferrugination and

dolomitization.

Bioclastic sandstones and pack/grainstones facies which constitutes the lower

part of this sequence is interpreted as a shoal environment and could represent an initial

transgressive hemisequence. During the subsequent sea level rise, more distal coral reef

related facies types retrograded over the shoal beds. The maximum flooding interval

could be represented at the algal coralline framestone beds. The relative fall in sea level

is marked by the transition from the shoal margin to the shoal facies in the upper part of

the sequence. The bioturbated wackestone layer on the top of this sequence suggests a

low accommodation restricted ramp environment and a sequence boundary between

sequence 2 and sequence 3.

Sequence 3

The thickness of Sequence 3 is about 40 m (Fig. 10b), starting with 18 m thick

bioclastic pack/grain/framestones. Most beds are moderately sorted and rich in fossils

like Crassostrea frondosa (De Serres), Alectryonella plicatula (Gmelin), Chlamys

 (Argopecten) submalvinae (Blanckenhorn), Ch. (Argopecten) macrotis (Sowerby), Ch.

malvinae (Dubois), Ch. senatoria (Gmelin), broken parts of echinoids, bryozoa, few

corals, foraminifers as Miogypsina intermedia Drooger. The thickness of the upper

part of the succession is about 22 m and consists mainly of yellowish white to white,

moderately compact, chalky bioclastic algal pack/grainstones. It yields some shell

fragments, echinoid plates and undefined foraminifera. Also, it yields Lithothamnium

sp. and Lithophyllum sp.

The lower part of this sequence is interpreted as a shoal related 432 facies, which

may represent a transgressive hemi-sequence. During the subsequent sea level rise,

more distal high energy shoal margin related facies types retrograded over the shoal

beds and the maximum flooding interval is interpreted at the reef beds. The relative

fall in sea level could be marked by the transition from the shoal margin related facies

to the proximal shoal environment in the upper part of the sequence.

Gabal Homeira Section

Sequence 1

Sequence 1 is 46 m thick (Fig. 10c). The lower part is 23 m and begins mainly

with varicolored, moderately compact, fractured, unfossiliferous, slightly calcareous

shale; yellowish brown, fine to medium grained, subrounded, moderately sorted

calcareous quartz arenite; poorly fossiliferous and intercalated with sandy dolostone

bands. Above these clastic beds, there are yellowish brown, soft to moderately

compact, slightly argillaceous, sandy pack/grianstones. They are rich with bivalves,

gastropodes, echinoderms, bryozaons, foraminifers, algae, in the form of Crassostrea

frondosa (De Serres), Alectryonella plicatula (Gmelin), Pecten fuchsi Fontannes, P.

 (P.) ziziniae Blanckenhorn, Chlamys malvinae (Dubois), Ch. (Aequipecten)

scabriscula (Matheron), Ficus sp., Turritella (T.) cleevelyi Abbass, T. (Eichwaldiella)

fouadi Abbass, T. (T.) terebralis Lamarck, Bursa faizae Abbass, Echinolampas amplus

Fuchs, E. plagiosomus Agassiz, Clypeaster marginatus Lamarck, Holoporella

polythele (Russ), Lithothamnium sp. and Lithophyllum sp., Operculina complanata

 (Defrance), Miogypsina intermedia Drooger.20

The upper part is about 22 m thick and consists mainly 455 of bioclastic

wacke/packstone beds, dominated by bivalves, gastropods, echinoderms and

crustaceas such as Crassostrea frondosa (De Serres), Alectryonella plicatula (Gmelin),

Pecten (P.) ziziniae Blanckenhorn, P. fuchsi Fontannes, P. (Oppenheimopecten)

benedictus (Lamarck), P. erythraensis Sowerby, P. beudanti Basterot, P.

 (Flabellipecten) flabelliformis (Brocchi), Linga (L.) columbella (Lamarck), Cardium

sp., Anomia burdigalensis Defrance, A. (A.) ephippium Linné, Conus (Lithoconus)

mercati Brocchi, C. (Conolithus) melficus Desio, Ficus reticulatus Lamarck,

Clypeaster sp., Balanus concavus (Bronn). This sequence is capped by gray,

moderately compact, fractured, fissile, unfossiliferous claystone.

The lower part of this sequence is characterized by clastic beds, could be

interpreted as a restricted ramp environment deposited under low energy conditions

forming a transgressive hemi-sequence. During the subsequent sea level rise, the distal

open marine back shoal related facies types retrograde over the restricted ramp beds.

So the maximum flooding interval is represented on the back shoal beds. Relative

decrease in the sea level is marked by the transition from the distal back shoal to the

proximal tidal flat related facies found in the upper part of the sequence. The claystone

unit at the top of this sequence may indicate a low accommodation peritidal

environment and represent the sequence boundary between sequence 1 and sequence2.

Sequence 2

The The thickness of sequence 2 of the Homeria section is about 477 35 m (Fig. 10c).

The lower hemi-sequence is 21 m thick and starts with yellowish brown, moderately

compact, angular to subrounded, moderately sorted, poorly fossiliferous fine to medium

calcareous quartz arenite. Above these sandstone beds, there are yellowish white,

moderately compact, sandy bioclastic pack/grainstones. They are rich in Scutella

ammonis Fuchs, Parascutella stefaninii (Desio), Pecten (P.) cristato-costatus Sacco,

Miogypsina intermedia. The thickness of the upper part of this sequence is 14m

containing marl beds crowded with oyster bank. The sediments represent the matrix

between oyters, which are mainly represented by Crassostrea frondosa (De Serres),

Alectryonella plicatula (Gmelin). Also, it yields Pecten (P.) cristato-costatus Sacco,

broken parts of Scutella ammonis Fuchs and Parascutella stefaninii (Desio).

The lower part of this sequence consists of sandstone beds which could be

interpreted as a restricted ramp environment that was deposited under low energy

conditions and formed a transgressive hemi-sequence. During the subsequent sea level

rise, the distal open marine shoal related facies types retrograded over the restricted

ramp beds. The maximum flooding interval is interpreted at the grainstone shoal beds.

The relative decrease in sea level is marked by a transition from the distal shoal to the

back shoal related facies in the upper part of this sequence.

 Sequence 3

Sequence 3 attains about 35 m thick in Homeira section (Fig. 10c). The

thickness of the lower hemi-sequence is 16 m and starts with yellowish white

bioclastic wacke/packstone beds, containing broken parts of echinoids as Scutella

ammonis Fuchs, Parascutella stefaninii (Desio) and echinoid spines; algae as

Lithothamnium sp. and Lithophyllum sp.; and foraminifera as Amphistegina 501 sp. Above

wacke/packstone beds, there are brownish white, moderately to highly compact,

massive sandy bioclastic pack/grainstone beds. They yield oysters and Chlamys

(Macrochlamys) sardoa Ugolini and other small-sized pectinids; molds of other

bivalves as Cardium sp., Clavagella sp., Gastrana sp., G. laminosa (Sowerby), Arca

(Anadara) grondica Mayer; gastropods as Turritella (T.) terebralis Lamarck, Ficus

sp., Lanistes (L.) mahmoudi Abbass, Luria (L.) salwae Abbass, Oliva (Neocyclindrus)

wagihi Abbass, Planorbis (P.) nakanoi Abbass; scleractinian corals and bryozoans.

Also they yield foraminifers as Heterostegina sp., Amphistegina sp. and red algae.The

upper hemi-sequence is 19 m thick, it consists of bioclastic sandy wacke/packstone

beds intercalated with mudstone bands containing broken shells, echinoids and

gastropods.

The lower part of this sequence consists of bioclastic wacke/packstone beds

that could be interpreted as the back shoal facies deposited under low energy

conditions during a transgressive hemi-sequence. During the subsequent sea level rise,

the distal open marine shoal related facies types retrograded over the inner back shoal

beds. The maximum flooding interval could be interpreted at the grainstone beds. A

relative decrease in sea level is marked by the transition from the distal shoal to the

proximal back shoal facies in the upper part of this sequence.