Facies and stratigraphy of early to middle cretaceous (Late Aptian-Early Cenomanian) strata from the...

[ FACIES I 19 I 77-96 Taf. 18-20 1 6 Abb. I ERLANGEN 1988 1

Facies and Stratigraphy of Early to Middle Cretaceous (Late Aptian - Early Cenomanian) Strata from the Northern Rim of the

African Craton (Gebel Maghara - Sinai, Egypt),

Fazies und Stratigraphie unter- bis mittelkretazischer Ablagerungen (Oberapt- Untercenoman) vom Nordostrand des afrikanischen Kratons

(Gebel Maghara- Sinai, ,~,gypten)

Jochen Kuss , Berlin und Felix Schlagintwei t , MiJnchen

KEYWORDS: MICROFACIES - BIOSTRATIGRAPHY - ORBITOLINIDS - CALCAREOUS AI.~AE - FACIES MODELS - PALEOGEOGRAPHY - SINAI/EGYPT - EARLY TO MIDDLE CRETACEOUS

SUMMARY

Thin-section analysis of Late Aptian/Early Cenoman- ian limestones was carried out in respect to the distribution of components and biota. All the sedimentological data were used for interpreting the depositional environment The sequence starts with Early Cretaceous sandstones; sandy dolomites form the transition to massive limestones, which prevail in the middle and upper parts of the section. They indicate shallow marine carbonate platform conditions at the northern rim of the African Craton: Thick accumulations of tidal carbonate shoals interfinger with quiet-water subtidal and intertidal to supratidal strata. The paleogeographic importance of the sequence is emphasized by comparison with contemporaneous strata in Israel and northern Egypt.

Orbitolinids are most important fossils for stratigraphic analysis: Dictyoconus algerianus, Orbitolina (M.) texana, O. (M.) subconcava and O. (M.) aperta were joined by other minor foraminifera and a diverse algal flora. The youngest dateable sample with O. (M:) aperta and O. (M.) subconcava indicates a Late Albian age (Fig. 5); the overlying sequence ranges to the Cenomanian.

ZUSAMMENFASSUNG

Es wurden mikrofazielle D~,mschliffuntersuchungen an Kalken des Oberapt-Untercenoman durchgeffihrt. Die

Abfolge beginnt mit unterkretazischen Sandsteinen - san- dige Dolomite leiten tiber zu massiven Kaiken, die in den mittleren und oberen Profilabschnitten tiberwiegen. Sie zeigen eine flachmarine Karbonatplattform am Nordrand des Afrikanischen Kratons an, die durch Verzahnung yon m~chtigen Kalksandbarren mit subtidalen Ruhigwasserab- lagerungen ininter- bis supratidalen Bereichen gekenn- zeichnet ist. Die palaogeographische Bedeutung dieses Prof'des wird durch Vergleiche mit zeitgleichen Ablagerun- gen in Israel und Nord~gypten verdeutlicht.

Die stratigraphische Einstufung erfolgte mit Orbito- liniden: Dictyonconus algerianus, Orbitolina (M.) texana, O. (M.) subconcava und O. (M.) aperta wurden durch weitere Foraminiferen und Algen erganzt. Die jtingste datierbare Probe zeigt mit O. (M.) aperta und O. (M.) subconcava oberes AIb an (Fig. 5); die tiberlagernde Abfolge reicht ins Cenoman.

1 INTRUDUCTION AND GEOLOGICAL SETTING

The present work deals with the description of facies and stratigraphy (based on orbitolinids) as well as the paleogeographic importance of the Cretaceous section of Gebel Maghara/northern Sinai (Fig. 1). The sediments range in age from the Late Aptian to the Early Ceno- manian, and are lithostratigraphically grouped into the Rizan-Aweiza and Halal Formations (SAID, 1971) or the Hatira and Hazera Formations (BARTOV et al., 1981).

Addresses: Dr. J. Kuss, Institut ftir Geologie und Pal~iontologie, Technische Universi~t, Ernst-Reuter-Platz 1, D-1000 Berlin; Dipl.-Geol. F. Schlagintweit, Institut fOr Pal~ontologie und historische Geologie, Universi~t, Richard-Wagner- Su'aBe 10, D-8000 Miinchen

78

Fig. 1. Geographic position of the Early to Middle Cretaceous section from Gebel Maghara (Sinai/Egypt). The sample numbers (1-20) are indicated in the columnar section (left). Geographische Lage des unter-/mittelkretazischen Profils am Gebel Maghara (Sinai/~gypten). Die Probermummern (1-20) sind am Profil (links) angegeben.

The most important formation names of Early/Middle Cretaceous strata in Egypt and adjacent areas are summarized in Fig. 2. These different formations vary in litho- logy, owing to their paleogeographic positions. BOTr- CHER (1985) collated many data of the Early Cretaceous deposits from the Western Desert of Egypt and found a notable thickening and diachronism of the strata from south to north.

The Precambrian crystalline basement of the Arabian- Nubian Shield crops out in the southern part of the Sinai peninsula, and is covered unconformably by younger sediments (Fig. 1). All Phanerozoic transgressions flooded southwards onto the Arabian-Nubian Craton. Shallow marine strata and their terrestrial (Nubian) equivalents of Cambrian, Carboniferous, Triassic, Jurassic and Creta- ceous ages were found in different localities of the peninsula. The following simplified and generalized sedimen-

tation pattern can be repeatedly recognized in all these units: Fluvial-eolian sandstones in the south interfinger with shaly/sandy marine deposits and open-marine carbonates further north (Fig. 6).

The northern part of the Sinai is characterized by several major folds, which are fractured along fault structures. Both tectonic structures run in NE-SW-directions. They continue to the west, across the Gulf of Suez (KUSS & MALCHUS, 1988) and to the Negev and Leba- non (WOLFART, 1967) further to the northeast. Folding started during Late Cretaceous times in the Levant, spanning an area described as the 'Syrian Arc System' by SAID (1962). Synsedimentary tectonic movements have been seen since the Late Cenomanian (KUSS & MALCHUS, 1988) and characterize the unstable shelf areas; the stable cratonal shelf continues further to the south.

79

CenomonJQn

Albion

Aptinn

BarremiQn

Western Desert ( south p~rt)

BOTTCXER.1982

Maghrabi Fro.

Sabaya Fm

Abu Bollas Fm.

Western Desert (north part)

METWALLI et o1.1979

Abu Subeiho

Fm.

Atamein Fm.

Alam El- Buieb Fm.

Gulf of Suez

ABDALLAH et at.1965

Oolalo Fm.

Malha Fm.

Sinai

SAIO, 1971

Halal Fro.

Risan-

Aweiza Fm

Isra~!

8ARTOV el o1.1981

Hazem Fro.

Hatirct

Fm.

Fig. 2. Correlation chart of the most important lithomatigraph- ir units of the Early to Middle Cretaceous used in Israel and EgypL KorrelatioustabeUe der wichfig- sten lithostzatigraphischen Ein- heiten (Unter-/Mittelkreide) yon Israel und Agypten.

The Early to Middle Cretaceous section of Gebel Mag- hara major represents a unique sequence of fossiliferous, shallow water carbonates. Extensive regions in Egypt and NE Africa were emergent during those times, or were covered by thick sandstones, silts and shales. Only the northernmost rim of the African Craton was flooded by the Late Aptian/Albian transgression. West of the Gulf of Suez (Galala Mountains), non-fossiliferous 'Nubian' clastics represent contemporaneous deposits (BANDEL et al., 1987). Early Cretaceous marine strata are known from a few subsurface and surface descriptions in Egypt (FAWZI & NAIM, 1964, A B D A I L A H et al., 1965, BOTTCHER 1982 and 1985, METWALLI & ABD EL- HADY; 1975). These authors described clastic-dominated deposits with a few dolomite/limestone intercalations. The Late Aptian-Early Cenomanian limestones discribed here represent a transgressive sequence; comparable lithologies are only known from the northernmost areas of the Levant coast (GRADER & REISS, 1958; BRAUN & HIRSCH, 1987).

The contact between Jurassic and Lower Cretaceous deposits in the Gebel Maghara area is unconformable (SAID & BARAKAT, 1957). This has also been confirm- ed in neighbouring sections in Israel (FREUND et al., 1975). FREUND et al. attribute the Jurassic/Cretaceous hiatus to a global regression associated with the Nevadian- Neocimmerian orogenic phase. The strata of the overlying Late Cenomanian/Early Turonian transgression were described in detail by KUSS & MALCHUS (1988).

2 DESCRIPTION OF THE LOCALITY

The outcrop of Gebel Maghara is a huge domai anti- cline, which is part of a NE-trending folded structure (Fig. 1). The core is composed of Jurassic strata (Bathon- ian- Kimmeridgian) several hundred meters thick. The Early Cretaceous marine outcrops were found near the eastern flanks of the structure (Khasm el Mistan). This area is presently exposed as a result of Early Neogene doming.

The non-fossiliferous sandstones at the base of the 250 m thick section (Fig. 1) are possible equivalents of the Middle/Late Aptian regression, described in several localities of the Arabian Croton (HARRIS et al., 1984).

They grade into ferruginous sandstones and dolomites with diagenetically altered rudists. The carbonate sedimentation started in the Gebel Maghara area during Late Apt- ian times, and persisted in the Northern Sinai up to Tur- onian times (with a few elastic intercalations). The lower carbonates with marls and dolomites reveal some sandy/ silty intercalations, which decrease towards the top, where thick, massive oolitic and bioclastic limestones prevail (intercalated with thick marly limestones).

The limestone-dominated succession of Gebel Magha- ra was formed in shallow marine environments. The carbonate shelf was subdivided by thick, skeletal and oolitic shoals, with large-scale cross-stratification. These shoals were predominantly reworked during storms. Back shoal wackestones interfinger with lagoonal foraminiferal mudstones, birdseye limestones and algal laminates. A considerable number of quartz grains and rock fragments (eroded from the crystalline basement and the older Nub- ian sandstone) is admixed in the lower part of the section. The Albian-Cenomanian carbonate shelf dips gently to the north and is rimmed by rudist reefs, which were described from neighbouring outcrops in Israel (SASS & BEIN, 1982).

The macrofossils of the section were described first by DOUVILLE (1916). Based on MAHMOUD (1955) SAID (1962) listed the most important fossils of Aptian/AIbian age. The sediments which are the subject of this study range in age from Late Aptian (LEWY & RAAB, 1976) to Early Cenomanian; the biostratigraphic subdivision is mainly based on orbitolinids (SCI-IROEDER & NEU- MANN, 1985).

3 MICROFACIES

The distribution of the microfacies assemblages within the limestones of Gebel Maghara and their most important constituents is illuslrated in Fig. 3. The analysis of the different microfacies types can be simplified by grouping them into associations which are present in several horizons. Three main carbonate facies-types (MF I, 11, HI) were subdivided into 7 microfacies-types.

The numbers 1-20 (indicated in Figs. 1, 3) represent superordinate units, which were summarized according to lithologic and sedimentologic criteria. 1 to 3 samples per

80

I 2 3 ~ 5 5 7 8 9 10 11 12 13 1~ 15 15 17 18 19 20

III

112 I/I

1 1 3 ~ .

1 / ~ ; 4"

1 / 5 a~ r

II 0 LL

III

cortoids

ooids

oncoids

peloids

quartz

O. (hr.) apeJ

O.(M) subco~

O. (b4,) texat

D. a lge r i a t

Orb i to l in ie

S, rain u ta

S. cf. aurunc

C. gr. pavoni

Nezzazata

L i tuo l idae

Textu lar i ia

M i l io l idae

,4. cf. pc<loft

C. sugden i

N. cre race<

Trinocladu'.

K. belgicurn

b4. lugeoni

P. irencte

P cf, hadhnan

A. aegograpil

Hal imeda s

Ac icu lar ia

Algal debri

Fig. 3. Distribution of facies types (MF) and most important foraminifera/calcareous algae. Number of units 1-20 correspond to the section in Fig. 1. Verteilung der Faziestypen (MF) und der wichtigsten Foramini- feren und KalkalgerL Die Nume- rierung (1-20) entspricht den Pro- bennummem van Fig. 1.

unit were taken; it is possible therefore, that different microfacies-types may occur within one single unit (Fig. 3).

"MF I - Shoal facies The massive, thick-bedded layers of the middle and up-

per part of the section in particular represent concen- trations of allochthonous material formed in shoaling wave zones. This is indicated by large-scale cross-bedding structures, best visible on weathered surfaces, as well as by granulometric characteristics revealed by thin-section analysis. Many shoal horizons are characterized by a conspicuous vuggy porosity caused by freshwater leaching.

I/1 Oolitic limestones (PI. 18/1) Oolitic limestones are frequent in different horizons of

the sequence. Whereas the basal oolitic horizons of XI/20 (Fig. 1) are intercalated between sandstones and marly dolomites, those from the upper part of the sequence (cf. XI/10, 19, 20) form massive beds of 0.8 - 5.7 m thick- ness, with cross-bedding structures.

Foraminifera, reworked bioclasts, echinids, brachio- pods (both punctate and impunctate), bivalves, coralline and codiacean algae are the most important biota of this facies type.

Many ooids are characterized by tangential microstructures in XI/10 and 20; almost all of them are circular and have diameters of 0.3 to 0.8 mm. They are often agglutinated by micritic cements, forming ooid lumps. Radi- al fibrous ooids are admixed in the two above mentioned units, even predominating in units XI/10 and XI/19 (PI. 18/1). They are often distorted and broken up by shrink-

81

age pores (PI. 18/3). Radial fibrous ooids are considered to form in protected shallow water environments (PON- CET, 1983; FLt2GEL, 1982). Similar conditions are probably responsible for the formation of the ooids described here. They were later reworked and deposited in thick coastal shoals. Both ooid types are often micritized by algal or fungal borings. Their nuclei are composed of subangular quartz grains, fragments of echinoderms, molluscs and peloids.

The oolitic limestones of the basal horizons are intercalated between sand- dominated units, often resulting in impregnations by Fe-hydroxides. These yellowish/brown crusts surround most of the components in the limestones.

The micritc matrix was almost completely winnowed out. Sparitic cements prevail and can often be differentiat- ed into an early fine-grained cement, whereas the residua]- pores were later filled by coarse and blocky cements. Sty- lolitic contacts between ooids or between the other components are often intensified by limonitic impregnations.

I/2 Echinoderma] grainstones/packstones Almost 50 % of the total biota content is made up of

echinoderm debris, predominantly echinoid plates. Frag- ments of molluscs, including a few rudists, occur, all within a well-sorted grain fraction of 0.8 to 1.8 mm. Or- bitolinids, lituolids and textulariids are less common; al- ga] debris is represented by Acicularia sp., MarineUa lugeoni and fragments of codiaceens. Oncoids are rare; encrustations are often formed by M. lugeoni. Most components are broken and abraded; all are embedded in a sparitic groundmass, indicating deposition in agitated water.

113 Pelsparitic grainstones Densely packed bioclastic limestones with only a few

fecal pellets; the majority of the peloids was either formed by intense micritization, or was derived from organic pelleting of lime mud. Almost all the components are micritized to a different extent, indicating a shallow-water depositional environment. Foraminifers are rare; only a few textulariids and miliolids are present; Sabaudia minuta (XI/1) and orbitolinids (X116) were found. Fragments of algae are common (XI/6). These pelsparitic grainstones interfinger with echinodermal grainstones/packstones.

114 Shell rudstones(Pl. 18/2) The thick oolitic limestones of the middle and upper

part of the sequence interfinger with massive, large-scale crossbedded layers, composed mainly of shell fragments (XI/5, 9). The elongated allochems are well-rounded and well-sorted, often with imbricated textures. The shells are sligthly micritized, and/or are surrounded by thin oncolitic crusts (PI. 1/2). Whole rudists were occasionally found in these beds, suggesting that most of the debris was formed by the erosion and reworking of these rudists as well as other molluscs. The composition changes within the 2-5 m thick layers: peloids, gastropods, algal debris (often balls of Marinella lugeom'), echinoderms, ooids or quartz grains prevail with changing frequencies. This facies type is characterized by a conspicuous bi-

model sorting, which demonstrates the mixing of components, originally formed in different depositional environments.

I/50rbitolinid-algal grain-/rudstones (P1. 18/3, 4) Densely packed green algae, echinoderms, mollusc

shells, orbitolinids, miliolids, ostracods, bryozoans, cor- Ms, intraclasts, ooids and oncoids, form massive layers. Many biota and allochems are coated by a radial fibrous oolitic cortex (PI. 18/3, 4). Both ooid-types - with tangential and radial microstructures - were found; their total frequencies range between 2 % and more than 50 % (X11 5). This facies-type documents the mixing of biota and components which originally lived in different ecosys- tems.

Orbitolinids, among them O. (M.) t ~ (P1. 20/4), were determined and used for the stratigraphic subdivision, along with O. (M.) aperta (PI. 20/7, 8) and O. (M.) subconcava (P1. 20/5, 6); the latter two occur in dolomitic marly varieties of facies-type 115. A well-preserved and diverse algal flora was identified, representing up to more than 50 % of the total biota. Among them are Halimeda sp. (PI. 18/3), Arabicodium aegagrapiloides (P1. 19/3), Trinocladus sp. (PI. 19/4,5) and T. tripolitanus (PI. 19/10).

MF II - laminated mudstones with fenestral fabrics (PI. 18/6)

Fenestra] fabrics occur preferentially in intertidal and supratidal environments (FLUGEL, 1982). In the section described they were usually found at the top of thick shoal beds, representing small-scaled regressive events.

Mud pebbles, which were probably formed by reworking of weakly consolidated lime mud, are the most common constituents. Some of these dark, micritic components act as nuclei for oncoids (some micritic crusts were possibly formed by red algae). The fauna and flora is very limited; except for individual miliolids no other biota were found.

The mudstones are intercalated with thin laminated horizons, which occasionally grade into thin pelsparitic layers. All of them are characterized by fenestral fabrics (P1. 18/6), dominated by irregular sparitic voids (birds- eyes), which are arranged in horizontal LF-A structures. They are connected with desiccation sheet cracks, best visible in the outcrops. Later dolomitization processes are recorded by tiny euhedral dolomite crystals.

MF I/I - Foraminifera] wackestones (PI. 18/5, 7, 8) Burrowed wackestones with grainstone infillings were

found in different horizons of the sequence. The most frequent biota are bentic foraminifera, among them orbitolinids, lituolids, miliolids and textulariids. Single tests of very small foraminifera(Gavellinella sp.)were determined in X115, 7 and 13. Debris of molluscs (often micritized) and angular quartz grains make up 30 % of the total allochems. A few dasycladaceans of Cylindroporella sugdeni occur in XI/11, 12 and 18.

Larger foraminifera prevail in XI/13, 14 and 16 with

82

Cuneolina gr. pavonia and miliolids, among them Der- ventina filipescui.. Dictyoconus algerianus indicates a Late Aptian age of unit XI/16. These foraminiferal wackestones interfmger with micritic wackestones, containing broken gymnocodiacean and dasycladacean remains, and a few benthic fordminifera (XI/13, 14). This 'algal debris facies' was first described by ELLIOTI" (1958) from Cretaceous deposits of the Middle East.

4 MICROFOSSILS

The microfossil assemblage of the Early to Middle Cretaceous carbonates from Gebel Maghara is similar to those described from other Tethyan regions. The diversity tends to be lower in comparison to the Urgonian limestones of southern France, the Cretaceous of Iberia and the Mediterranean area (ARNAUD-VANNEAU, 1980). Biostratigraphic correlations (based on orbitolinids) are possible, although endemic faunal elements occur in all regions. The comparable Early Cretaceous Tethyan micro- fauna is characterized by orbitolinids, lituolids, cuneoli- nids, trocholinids and miliolids; the flora by dasycladacean, gymnocodiacean and coralline algae.

this form is restricted to the southern margin of the Te- thyan realm (Fig. 4), i.e. the so-called ~oioprovince africaine' (CHERCHI & SCHROEDER, 1982). This new occurrence from the Sinai fits well with the pattern of faunal provincialism indicated by many larger foraminifera, especially orbitolinids in the Early and Middle Cretaceous (SCHROEDER et al., 1978; SAINT-MARC, 1982; MOULLADE et al., 1985; ARNAUD-VAN- NEAU, 1980).

D. algerianus represents an excellent guide fossil for Late Aptian strata, according to CHERCHI & SCHROE- DER (1982).

4.1 Foraminifera

Foraminifera are the most common and important microfossils, along with calcareous algae. The following foraminiferan families were found with varying frequencies in nearly all the thin sections: Ataxophragmiidae, Lituolidae and Orbitolinidae. A brief description, based on the classification by LOEBLICH & TAPPAN (1984), is given for those species which are important for stratigraphic and paleogeographic analysis.

Superfamily Orbitolinacea MARTIN, 1889 Family Orbitolinidae MARTIN, 1889 Subfamily Dictyoconinae MOULLADE, 1965 Genus Dictyoconus BLANCKENHORN, 1900 Dictyoconus algerianus CHERCHI & SCHROEDER, 1982 -PI. 20/1, 2, 3

Test conical (angle approximately 60 ~ with a convex base of 20-29 (max. 35) discoidal chambers in adult specimens. The initial chambers (4-5) are arranged in a very small spire. The chambers increase only slightly in height during ontogeny (about 0.06 mm in the last chamber). In the marginal zone each chamber is divided by one (sometimes by two) vertical plates, which become slightly thicker towards the end. Horizotal plates are missing. The central area consists of well developed pillars, alternating from one chamber to the next. Size (mm): height (H): 1.1 - 1.7 (max. 2.2); diameter (D): 0.9 - 1.6 (max. 1.8); H/D rnax./min.: 1.9/1.0

Remarks: This is the first report of the occurrence of primitive orbitolinids (Dictyoconidae) from the Sinai (cf. the Mediterranean distribution by MOULLADE et al., 1985). The distribution of D. algerianus indicates that

Fig. 4. Mediterranean distribution of Dictyoconus algerianus CHERCHI & SCHROEDER, 1982. Locations 1, 2, 3 from CHERCHI & SCHROEDER (1982); location 4 from SARTONI & COLALONGO (1964), who drew D. algerianus as Orbitolinopsis kUiani and Coskinolina sumilandensis; location 5 from LUPERTO SINNI (1966), who drew D. algerianus as C. sumilandensis; location 6 from own observations. Circummediterrane Verteflung yon Dictyoconus algerianus CHERCHI & SCHROEDER, 1982. Die Fundpunkte 1, 2, 3 nach CHERCHI & SCHROEDER (1982); Fundpunkt 4 naeh SARTONI & COLALONGO (1964), die D. algerianus als Orbitolinopsis kiliani und Coskinolina sumilandensis abge- bildet haben; Fundpunkt 5 nach LUPERTO SINNI (1966); Fundpunkt 6 nach eigenen Beobachtungen.

Subfamily Orbitolininae MARTIN, 1890 Genus Orbitolina d'ORBIGNY, 1850 Subgenus Mesorbitolina SCHROEDER, 1962 Orbitolina (M.) texana (ROEMER, 1849) - PI. 20/4 Orbitolina (M.) subconcava LEYMERIE, 1878 - PI. 20/

5,6 Orbitolina (M.) aperta (ERMANN, 1854) - PI. 20/7, 8

A detailed description of these three species was given by SCHROEDER (in SCHROEDER & NEUMANN 1985). It is important to mention that these forms can be distinguished by their shape, size and differentiation of the complex embryonic apparatus.

Remarks: The microspheric forms of Orbitolina (M.) aperta, which represent the largest known orbitolinas, attain a size of more than 3 cm in sample XI/6.

The essential characteristics for identifying the above-

83

mentioned species are summarized in the following Table, based on the forms found in thin sections XI/5, 6, 7, 12, 18:

bers. As mentioned by BRONNIMANN et al. (1983), Dicyclina represents a more specialized form and is re- garded as the final stage in the evolution of a flabelliform Cuneolina.

Fig. 5. Slxatigraphie ranges of O. (M.) texana (ROEMER, 1849), O. (M.) subconcava LEYMERIE, 1878 and O. (M.) aperta (ERMAN, 1854) after SCHROEDER (1975) and SCHROEDER & NEUMANN (1985). Slxafigraphische Reichweiten yon O. (M.) texana ROE- MER, 1849), O. (M.) subconcava LEYMERIE, 1878 und O. (M.) aperta (ERMAN, 1854) nach SCHROEDER (1975) und SCHROEDER & NEUMANN (1985).

Subfamily Sabaudiinae BRONNIMANN, DECROUEZ & ZANINEITI, 1983 Genus Sabaudia CHAROLLAIS & BRONNIMANN, 1965 Sabaudia minuta HOFKER, 1965 - Pl. 20/12

S. minuta is distinguished from the other species of the genus by its simple internal structures, small size and a trilocular juvenarium. For a detailed description see ARNAUD-VANNEAU & CHIOCCHINI (1985).

Remarks: The stratigraphical range of S. minuta varies in the Mediterranean region: It occurs up to the Ear- ly Barremian in the Iberian and French platforms, whereas in the Italian and Balkan regions, it appears for the first time in the Late Barremian. The Early Aptian and Late Albian transgressions enabled the residual Tethys to be colonized, as pointed out by ARNAUD-VANNEAU (1984). S. minuta has not been mentioned from Creta- ceous strata of the Middle East up to now, with the ex- ception of the Albian of the Zagros mountains (ARNAUD-VANNEAU & CHIOCCHINI, 1985).

In the section of the Sinai described here, S. minuta was found above the layers with Orbitolina (M.) subconcava and O. (M.) aperta. The co-occurrence of the latter two forms indicates a Late Albian age.

Superfamily Ataxophragmiacea SCHWAGER, 1877 Family Cuneolinidae SAIDOVA, 1981 Subfamily Cuneolininae SA/DOVA, 1981 Genus Cuneolina d'ORBIGNY, 1839 Cuneolina gr. pavonia d'ORBIGNY, 1839 - PI. 18/5; P1. 20/9, 10)

C. gr. pavonia represents a highly developed flabelliform Cuneolina with a convex base. The primary chambers of the test are divided by radial partitions into chamberlets, forming narrow rectangular shapes with a height approximately twice width. Secondary subepidermal partitions (both horizontal and vertical) are developed. Unilocular proloculus large, measuring about 0.11 mm in diameter. Size (in mm): height: 0.75 - 2.0; thicknessl 0.27 - 0.3

The angle of inclination ot the test varies too greatly to use the width of individual tests as a characteristic measurement.

Remarks: The stratigraphic range of C. gr. pavonia ex- tends from the Albian to the Turonian (SARTONI & CRESCENTI, 1962; VELIC, 1973); MOUTY & SAINT- MARC (1982) described it from the uppermost Aptian of Syria, which corresponds with the Sinai-occurrence together with D. algerianus.

Some specimen show a transition from Cuneolina to the discoidal genus Dicyclina, with more annular chain-

Sabaudia cf. auruncensis (CHIOCCHINI & 131 NAPOLI ALLIATA, 1966)

The conical, slightly curved test with an apical angle of 35-500; the chambers of the biserial stage may pro- trude to the exterior wall. A more detailed description has been given by ARNAUD-VANNEAU & CHIOCCHINI (1985).

Remarks: S. cf. auruncensis was found in layers XI/2 and XI/3, just below the limestones with S. minuta. The larger size of the test, the more frequent presence of horizontal plates within the marginal zone of the last chambers and the embryonic apparatus distinguish S. cf. auruncensis from S. minuta. The stratigraphic range of S. auruncensis is the Middle Aptian to the Middle Albian (ARNEAU-VANNEAU & CHIOCCHINI, 1985). It was described in Algeria by FOURCADE & RAOULT (1973).

Family Nezzazatidae HAMAOUI & SAINT-MARC, 1970 Genus Nezzazata OMARA, 1956

The trochospiral, planiconvex test with a granular, calcareous imperforate wall exhibits 2.5 whorls. A flattened, tooth-like outgrowth of the wall near the aperture might represent partitions of supplementary chamberlets (REISS, 1957). WASFI & HATABA (1984) summarized the characteristics of the different Nezzazata-slr~ies.

84

Nezzazata cf. simplex OMARA - PI. 20/13

The ventrally convex test is characterized by an increase in the chamber diameters during the last half of the whorl. Size (in mm): diameter. 0.31 - 0.44; height: 0.17 - 0.21

wider at their distal end, with narrow pores on the main axis. Only primary branches (20-22) were found.

Remarks: The stratigraphic range of A. podolica is from the Upper Jurrassic/Lower Cretaceous (BASSOUL- LET et al., 1978). ELLIOTI" (1958) described it from the Lower Cretaceous of the Middle East.

Nezzazata sp. - P1. 18/8

The smaller tests are flattened: there are more chambers and the walls are thicker than they are in N. simplex. There is no thickening of the last whorl. Size(in mm): diameter: 0.25 - 0.29; height: 0.11 - 0.13

The following foraminfera are of minor slrafigraphic importance, but are comparable with f'mdings in adjacent contemporaneous strata.

Derventina cf. filipescui NEAGU was described by ARNAU-VANNEAU (1980) from Early Cretaceous limestones of Southern France. This form was found in many thin sections of the Maghara section. It occurs together with 'DictyopseUa' libanica SAINT-MARC (described from Early Cenomanian strata of Lebanon) in micritic mi- liolid wackestones. Bolivinopsis sp., which has a characteristic planispiral coiling of the early stage and later a biserial arrangement of the chambers, with agglutinated, fine-grained calcareous walls was also found in these wackestones, along with Nummoloculina sp. and Pseudo- textulariella sp..

4.2 Calcareous algae

Calcareous algae are frequent in many horizons of the Gebel Maghara section (Fig. 3). The flora is characterized by a high frequency of udoteaceans and dasycladaceans, while coralline algae are of lesser importance. The latter are very abundant and diverse in the Albian 'facies de Vimport', known from many areas of the Tethyan realm: Pyren6es (CANEROT, 1974, BOUROULLEC et al., 1979), Hungarya (PEYBERNES, 1977) and the Northern Calcareous Alps (SCHLAGINTWE1T, 1987).

An algal flora similar to the section studied was described from the Albian of Estremadura/Portugal (REY et al. (1977).

The description of the most important forms is based on the classifications of ELLIOTT (1968), BASSOUL- LET et al. (1978) and BASSOULLET et al. (1983).

Family Dasycladaceae ~ G , 1843 Genus Actinoporella (ALTH, 1882) CONRAD et al., 1974 ActinoporeUa cf. podolica (ALTH, 1878) CONRAD et al., 1974- PI. 18/8

A. cf. podolica is characterized by a cylindrical axis (450-540 ttm in diameter) surrounded by irregularly spaced branches (outer diameter 1050-1280 IJ.rn); they are

Genus Cylindroporella JOHNSON, 1954 Cylindroporella sugdeni bTI J JOTI', 1957 - PI. 19/6, 7, 8

Thallus cylindrical; not segmented; large spherical sporangial cavities; primary branches perpendicular to the central stem. Size (in lam): outer 0ismeter (13): 720-930; diameter of the axial stem (d): 125-150; diameter of the sporangia (ds): 170-2151am; number of sporangia per whorl: 6

Remarks: C. sugdeni has larger internal structures and a larger overall size than C. barnesi JOHNSON, 1954, both occur in Lower Cretaceous swata of the Middle East (ELLIOTI', 1968). BASSOULLET et al. (1978) consider C. elitzae BAKALOVA to be the junior synonym of C. sugdeni.

Genus Neomeris LAMOUROUX, 1816 Neomeris cretacea STEINNMANN, 1889 -PI. 18/'7

Segments up to 2.6 mm in length and 1.18-1.75 mm in diameter, cylindrical in cross-section; the central cavities axe 0.8-1.34 mm wide. Calcification surrounds the ovoid sporangia (94-112 Ixm) and the secondary branches (22-32 lam). Thallus uncalcified around the central stem and the primary branches.

Remarks: The size corresponds with the type material described by STEINMANN (1889).

Genus Trinocladus RAINERI, 1922 Trinocladus tripolitanus RAINERI, 1922 - PI/19/10

Cylindrical dasyclad with club- or paddle-shaped primary branches, smaller secondaries and many short and slender tertiary branches. Only a few sections; size range within that given by PIA (1936).

Remarks: T. tripolitanus was described in Egypt from Cenomanian/Turonian swata (ICt.ISS, 1986).

Trinocladus sp. - PI. 19/4, 5

A great number of sections are often leached out and eroded; only secondary and tertiary pores are visible.

Remarks: Size is larger than T. tripolitanus; secondary pores with paddle or globule shapes; possibly a new species of Trinocladus.

Size (in I.tm): Trinocladus tripolitanus Trinocladus sp. D 610-770 810-1090 d 150-175 220-700 Pl 64-70 --- I>2 31-39 35-48 I> 3 7-10 7-10

85

Family Corallinaceae (LAMOUROUX) HARVEY, 1849 Genus MarineUa PFENDER, 1939 Marinella lugeoni PFENDER, 1939 - PI. 19/9

Cauliflower-shaped thalli with closely packed filaments (7-11 lam in diameter). Flat encrusting pads or part of oncolitic encrustafions or free rhodolitic nodules 1.6 mm in diameter.

Remarks: The systematic position is still under dis- cussion. BECKMANN & BECKMANN (1966) classified M. lugeoni under the Codiaceae; many recent authors see it as belonging to the CoraUinaceae (LEINFELDER & WERNER, 1987). According to MASSE (1979) and HOFLING (1985), M. lugeoni is possibly a cyanophy- cean or stromatolite.

Family Gymnocodiaceae ? ELLIOTT, 1955 Genus Permocalculus ELLIO'ffF, 1955 Permocatculus irenae ELLIO'I'T, 1958 -P1. 19/1

Slightly segmented thallus; irregular fmger-like segments or pinching and swelling units with fine pores at the outer edge; internal sporangia are not identifiable. Calcification of the plant varies from very thin to thick layers or total calcification. The size especially the pore diameters, coincides well with measurements made by ELLIOTI" (1958). Size (in lxrn): length of the thallus (L) 1700-2100; diameter of the segments (D): 440-710; pore diameter (p): 8- 15

Remarks: According to POIGNANT (1978) P. irenae occurs in Albian/Cenomanian strata.

Family Solenoporaceae PIA, 1927 Genus Parachaetetes DENINGER, 1906 Parachaetetes cf. hadhramautensis ELLIOTF, 1959 - PI. 19/11

Rounded thallus (diameter up to 2.25 mm) often recrystallized. Curved tubular rows of ceils; transverse partitions indistinct. Cell-diameter varies between 25 and 29 gin.

Remarks: P. asvapatii is known from the Campanian/ Maastrichtian of Egypt (KUSS, 1986); it has thicker cell sizes, with clear tranverse cell walls. The decrease in the cell diameters of Paracheatetes over time, as assumed by ELLIO'IT (1959), does not seem probable. P. hadhramautensis was first described from the Aptian-Albian of Iraq and Southern Arabia.

Genus Kymalithon LEMOINE & EMBERGER, 1967 Kymalithon belgicum (FOSLIE) LEMOINE & EMBER- GER, 1967 -PI. 19/12

K. belgicum represents a typical encrusting red algae; the hypothallus consists of fdamentous cells with no dis- tinct arrangement. The perithallus is much thicker, with short cells (14 tam in diameter, 14-25 lain high).

Remarks: The slratigraphic range of K. belgicum was described by POIGNANT (1981) as the uppermost Aptian to the lowermost Cenomanian.

Family Udoteaceae sensu BASSOULLET et al., 1983 Genus Arabicodium ELLIO'I'F, 1957 Arabicodium aegagrapiloides ELLIOTT, 1957 - PI. 19/3

Thin cylindrical segments, occasionally branched. The medullary zone has slightly wavy longitudinal threads; the cortical zone has very free radial threads. Size (in gin): length of the fragments (L): 800-3350; outer diameter (D): 740-876; diameter of the medullary zone (d): 310-545

Remarks: A. aegagrapiloides is distinguished from the similar genus Halimeda and Boueina by the size and shape of the medullary and cortical zones (BASSOUL- LET et. al., 1983). The stratigraphic range was described by ELLIO'IT (1957) as the Upper Jurassic to Albian.

Halimeda sp. - PI 18/3

Cylindrical thallus with long segments; large medullary zones with nearly parallel, relatively thick filaments; they continue in fine bifurcated threads in the cortical layer. Size (in pan): max. length (L): 3450; outer diameter (D) 125-153; diameter of medullary zone (d): 600-900; diameter of medullary threads (dtc): 35-50; diameter of cortical threads (dtm): 7-10

Remarks: Halimeda sp. can be distinguished from A. aegagrapiloides by stronger calcification as well as size.

In addition to the algae described here, several less common forms were also determined: Heteroporella sp. (PI. 18/4), Archeaolithothamnium sp. and Solenopora sp.

5 DEPOSITIONAL ENVIRONMENT OF THE CRETACEOUS SUCCESSION

The sequence as a whole documents deposition in shallow water environments. The lower part is characterized by the strong terrigenous input of quartz sands and gravel beds. These sandstones were deposited in shallow (intertidal ?) environments, indicated by flaser and hering- bone cross-bedding. Several soil horizons are intercalated, with bleached and weathered beds co-occurring with ferruginous crusts. Sandy dolomites (often desintegrated into pebbles) occur further to the top. Badly preserved rudists were found in the upper dolomitic horizons. Iron- impregnated oolitic limestones are intercalated between the dolomitic sandstones. The clastic content decreases in the overlying units.

The lower limestone beds (XI/19, 20) contain only minor amounts of quartz (1-5 %), and are represented by

86

both quietwater deposits (foraminiferal wackestones) and sediments formed in agitated water (oolitic grainstones). The wackestones represent deposits of SMF 9, formed in shallow neritic water of open circulation, while the peloidal grainstones of SMF 16 characterize restricted marine shoals; both typify facies belt 7 (WILSON, 1975), i.e. shallow inner shelf areas.

The carbonate shoal facies starts with the massive limestones of XI/17. The oolitic and bioclastic grain-h'ud- stones were formed in agitated water, i.e. in facies belt 8 (SMF 11) of WILSON (1975), characterized by winnowed platform sands and oolitic shoals. These coarse grainy sediments were piled upby tidal currents, forming coastal bars and shoals in shallow lagoons and bays.

The shoal sedimentation continues to the top of the sequence, and can be subdivided into several smaller transgressive-regressive cycles. The transgressive sedimentation starts with marly or dolomitic limestones (2.3-8.5 m

thick); they culminate in massive shoals of alloehthon- ous ooids and/or shell-fragments and allochems, which are overlain by laminated mudstones with fenestral fabrics (10-45 cm). Laminated to bioturbated pelloidal mudstones, grading into pelspadtes - both with fenestral fabrics - are common in restricted marine shelf lagoons; they clearly indicate inter- supratidal environments (SMF 19, facies belt 8).

6 PALEOGEOGRAPHIC SIGNIFICANCE OF THE SECTION

Outcrops of Early Cretaceous marine strata are very rare in Egypt',Thickeolian-fluviatile sands, silts and shales accumulated in most parts of North Africa, due to emer- gence of the shelf areas (KUSS, 1988):

A rich Aptian fauna and flora was investigated in

Fig. 6. The major paleodepositional environments during Late Aptian/Albian times are figured on a schematic map of northern Egypt and Sinai. Shallow-marine carbonates of the northern shelf areas int~rfinger with shaly/silty and sand- dominated deposits further south. During Apfian times, the transgression reached its southernmost extention (BOTrCHER, 1982). 1. Gebel Maghara: Described in the present work; 2. Gebel Tih: Unpublished section according to own observations: 3. Gebel Shebrawet: FAWZI & NAIM (1965); 4. Middle Wadi Qena: BANDEL es al; 5. Alamein-borehole: METWALLI & ABD EL-HADY (1975); 6. Bahariya: BAYOUMI et al. (1977); 7. Southern Dakhla Basin: BOTTCHER (1985). Die wichtigsten Ablagerungsbereiche des Oberapt/Alb shad auf der schematisehen Karte yon .~gypten mad Sinai dargestellt. Die flaehmarinen Kalkablagerungen der nrrdlichen Sehelfbereiche verzahnen sieh mit tonig/siltigen bzw. sandigen Sediraenten weiter im Stiden. Der am weitesten nach Sllden gedchtete Meeresvorstol] wurde fur des Apt naehgewiesen (BOTrCHER, 1982). 1. Gebel Maghara: In vorliegender Arbeit besehrieben; 2. Gebel Tih: Unpubliziertes Profil nach eigenen Beobaehtungen; 3 Gebel Shebrawet: FAWZI & NAIM (1965); 4. Middle Wadi Qena: BANDEL et al. (1987); 5. Bohrtmg Alamein: METWALLI & ABD EL-HADY (1975); 6. Bahariya: BAYOUMI et al. (1977); 7. Stidliehes Dakhla Becken: BOTI'CHER (1985).

87

detail by B O T r C H E R (1982) from the Dakhla Basin in the southern part o f the Western Desert (Fig. 6). The strata of the Abu Ballas Formation were formed at the transitional zone between marine and fluvial facies, and were interpreted as prodelta deposits o f a shallow epicon- finental sea (BOTrCHER, 1985).

Marine deposits o f Aptian age were described from Gebel Shebrawet/Lake Bitter by FAWZI & N A I M (1964).

A B D A L L A H et al. (1965) described Aptian oysters from the western side of the Gulf of Suez.

Early Cretaceous marine sediments are also known from boreholes in northern Egypt: M E T W A L L I & ABD E L - H A D Y (1975) subdivided the series of the Alamein oil field into a lower, predominantly clastic unit, and an upper, mainly carbonate and dolomitic unit, with Orbito- lina discoidea (= Palorbitolina lenticularis).

The Aptian/Albian carbonates described by the last two authors may possibly be correlated with those from the Gebel Maghara. The Early/Middle Cretaceous coast- line continued forther to the NE, where comparable sequences were described from Israel (GRADER & REISS, 1958); W O L F A R T (1967) mentioned Aptian and Albian limestones with P. lenticularis from Lebanon and Syria. B A C H M A N N & RISCH (1979) described massive %rr- gon-like' l imestones from the Argonis peninsula (Greece), with microfacies and faunal similarities to the limestones described from Gebel Maghara. The diversity of the Lower Cretaceous microfossils from the Levant is lower than that from the Urgonian limestones of the northern coast o f the Tethys.

A C K N O W L E D G E M E N T

Samples were taken by the first author during a joint field trip with Prof. Dr. K. Bandel (Hamburg). The work was carried out with the financial support of the German Research Foundation (SFB 69) and the help of Prof. Dr. E. Klitzsch (Berlin). Our thanks to B. Dunker and H. Glowa (both TU Berlin) for their assistance in preparing drawings and photographs. We want to thank two ano- nymous reviewers for their critical comments.

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SAINT-MARC, P. (1978): Biostradgraphie de L'Albien, du C~nomanien et du Turonien du Liban. - Ann. Mira

89

G6ol. (Actes VI e Coll. africaln Micropal~ont. Tunis 1974), 28/2, 11-118, 2 pls., Tunis

-- (1982): Distribution pal&xk:ologique et pal6obiog6o- graphique de Grands Foraminif'eres benthiques du C~fto- manien. Rev. Esp. Micropal6ont., 14, 247-262, 5 figs., Madrid

SARTONI, S. & CRESCENT[, U. ( 1962): Richerche bio- stratigrafiche nel Mesozoieo dell'Apeunino meridio- hale. - Giotto Geol. Bologna, ser. 2, 29, 161-302, 42 pls., Bologna

SARTONI, S. & COLALONGO, M.L. (1964): Sul Cretaceo di Diutomi di Caiazzo (Caserta). - Mere. Soe. Geol. Ital.,4/2, 7-18, 6 pls., Rome

SASS, E. & BEIN, A. (1982): The Cretaceous Carbonate Platform in Israel. - Cret. Res., 1982/3, 135-144, 4 figs, London

SCHLAGINTWE1T, F. (1987): Allochthone Urgon-Kalke in Konglomeraten der basalen Gosau (Coniac) yon Ober- w6ssen (Chiemgau/N6rdlicheKalkalpen). - Mitt. Bayer. Staatss., Pal~ionL hist. Geol., 27, 145-158, 2 pls., 2 figs., Munie

SCHROEDER, R. (1975): General evolutionary trends in Orbitolinas. - Rev. Esp. Micropaleom., Mem. Espee., 1975, 117-128, 9 figs. Madrid

SCHROEDER, R., CHERCHI, A., GUELLAL, S. & VILA, J. (1978): Biozonation l~r les grands foraminif'eres du Jurassique sup6rieur et du Cr&ace inf6rieur et moyen des series n&itiques eat Algerie du Nord-Est. - Considera- tions pal6obiog6ographiques. - Ann. Min. Geol. (Actes VIe Coll. africain Micropal6ont. Tunis 1974), 28/2, 243-253, 2 pls., 2 figs., Tunis

SCHROEDER, R. & NEUMANN, M. (eds.) (1985): Les Grands Foraminif'eres du Cr6tac~ Moyen de la R6gion M6diterran6ene. - G6obios m~a. sp6e., 7, 160 p., 68 pls., 11 tabs., Lyon

SIMMONS, M.D. & HART, M ~ . (1987): The biostratigraphy of carbonate environments. In: HART, M.B. (ed.): Micropaleontology of carbonate environments. - 176-207, 5 pls., 12 figs., Chiehester (Ellis Horwoods)

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Manuscript received January 19, 1988 Revised manuscript received February 15, 1988 Manuscript accepted February 24, 1988

90

P l a t e

Fig. 1.

Fig. 2.

F~g. 3.

Fig. 4.

Fig. 5.

Fig. 6.

Fig. 7.

Fig. 8.

18 Different microfacies-types (MF) of the Late Aptian/Early Cenomanian limestones of Gebel Maghara (Sinai/Egypt)

Verschiedene Mikrofazies-Typen (MF) der Obempt/Untercenoman Kalke vom Gebel Maghara (Sinai-ggypten)

Oolitic grainstone (MF 1/1) with quartz-bearing oolumps (center) and mollusc fragments. Angular quartz grains act as nuclei for most radialfibrous ooids. Sample XI/10. x 18

Shell rudstone (MF I/4) mainly composed of mollusc-debris (partly micritized). White dots (arrows) indicate vuggy pores. Sample XI/9. x 7.1

Orbitolinid-algal rudstone (MF I/5) with Orbitolina cf. aperta (ERMAN, 1854) and Halimeda sp.; most components with oncoidal encrustations. Radialfibrous ooids are often distorted and broken up by shrinkage pores (arrows). Sample XI/5b. x 18

Orbitolinid-algal rudstone (MF I/5) with a fragment of Heteroporella sp., echinoid and mollusc debris. Many components are surrounded by a micritic cortical layer, radialfibrous ooids are partly distorted. Sample XI/5. x 18.5

Foraminiferal wackestone (MF III) with patchy neomorphic recrystallization. Dictyoconus algerianus CHERCHI & SCHROEDER, 1982 (left), Cuneolina gr. pavonia d'ORBIGNY, 1839 (right). Miliolids and textulariids occur in a peloidal/micritic groundmass. Sample XI/16. x 18

Laminated mudstone with fenestral fabrics (MF II), and LF texture. Reworked mud-pebbles and intraclasts. Sample XI/8. x 18

Foraminiferal wackestone (MF III) with Neomeris cretacea STEINMANN, 1889. Oblique section (right) and horizontal sections of internally leached-out and micritized specimens; ooids and bioclasts in a micritic peloid matrix. Sample XI/4,1. x 18.5

Foraminiferal wackestone (MF HI) with miliolids, textulariids and Nezzazata sp. (bottom right). Actino- porella cf. podolica (ALTH, 1882) with oblique section (left) and random sections (right). Sample XI/3. x 18.5

Fig. 1.

Fig. 2.

Fig. 3.

Fig. 4.

Fig. 5.

Fig. 6.

Fig. 7.

Fig. 8.

Oolitic grainstone (MF I/1) mit quarz-fiihrenden Oolumps (Zentrum) und Bruchstiicken yon MoUusken. Ungerundete QuarzkOmer dienen als Kerne der meisten radialfibr6sen Ooide. Probe XI/10. x 18

Shell Rudstone (MF I/4), hauptslichlich aus teilweise mikritisierten Molluskenbruchstiicken bestehend. Die weilMn Fl~chen (Pfeile) zeigen ausgel/Sste Porenriiume. Probe XI/9. x 7,1

Orbitolinen-Algen-Rudstone (MF I/5) mit Orbitolina cf. aperta (ERMAN, 1854) und Halimeda sp.; die meisten Komponenten haben onkoidische Umkrustungen. Radial-fibr0se Ooide sind h~iufig zerbrochen mad von Schrumpfrissen (Pfeile) durchzogen. Probe XI/5b. x 18

Orbitolinen-Algen-Rudstone (MF 1/5) mit einem Bruchstfick yon Heteroporella sp. und Echinodermen- /Molluskenfragmenten. Viele Komponenten haben mikritische Rindenkomumkrustungen; die radialfibr0sen Ooide sind teilweise zerbrochen. Probe XI/5. x 18,5

Foraminiferen-Wackestone (MF liT) mit fleckenhaft verteilten Rekristallisationsarealen. Dictyoconus algerianus CHERCHI & SCHROEDER, 1982 (links) Cuneolina gr. pavonia d'ORBIGNY, 1839 (rechts) mad miliolide Foraminiferen kommen in einer peloidreichen mikritischen Grundmasse vor. Probe XI/16. x 18

Laminierter Mudstone mit Fenstergefiigen (MF II) mad LF-Geffige. Aufgearbeitete Schlammger611e mad Intraklasten. Probe XI/8. x 18

Foraminiferen-fiihrender Wackestone (MF HI) mit Neomeris cretacea STEINMANN, 1889; schrage (rechts) und horizontale Schnittlage yon intern ausgel~Ssten mad mikritisierten stricken. Daneben Ooide mad Bioklasten in einer mikritisch-peloidreichen Matrix. Probe XI/4,1. x. 18,5

Foraminiferen-f'dhrender Wackestone (MF lid mit milioliden, textulariiden Foraminiferen und Nezzazata sp. (unten rechts). Actinoporella cf. podolica (ALTH, 1882) mit schr~ger (links) mad randlicher (rechts) Schnittlage. Probe XI/3. x 18,5

TAFEL 18

92

P l a t e 19

F i g . 1o

Fig. 2.

Fig. 3.

Fig. 4, 5.

~g. 6 ,7 ,8 .

Fig. 9.

Fig. 10.

Fig. 11.

Fig. 12.

Calcareous algae from Late Aptian/Early Cenomanian limestones (Gebel Maghara, Sinai/ Egypt)

Kalkalgen von Oberapt/Untercenoman Kalken (Gebel Maghara, Sinai/,~gypten)

Permocalculus irenae ELLIOTF, 1958 longitudinal/oblique section. Sample XI/12,3. x 52.5

Arabicodium sp., longitudinal section, partially leached-out medullary zone, cortical threads. Sample XI/7,1. x42

Arabicodium aegagrapiloides ELLIOT'F, 1957 - oblique/horizontal section with medullary and cortical threads. Sample XI/4,3. x 26.2

Trinocladus sp. with both leached-out and micritized primary branches and stem; secondaries and tertiaries are clearly visible: Fig. 4.: Oblique section of a compressed individual. Sample XI/7,2. x 55.5, Fig. 5.: Almost horizontal section. Sample XI/7,2. x 42.2

Different sections of Cylindroporella sugdeni ELLIOTF, 1957: Fig. 6: Longitudinal/random section. Sample XI/12,1. x 35, Fig. 7.: Horizontal section. Sample XI/12,3. x 46, Fig. 8.: Longitudinal/central section. Sample XI/12,2. x 52

Marinella lugeoni PFENDER, 1939 - globule colony. Sample XI/12. x 37

Trinocladus tripolitanus RAINER, 1922 - horizontal section. Sample XI/5,2. x 46

Parachaetetes cf. hadhramautensis ELLIO'I'F, 1959 - oblique section of a recrystallized thallus with curved cellrows. Sample XI/11. x 20

Kymalithon belgicum (FOSLIE) LEMOINE & EMBERGER, 1967 - thin hypothallus (below) and thick perithallus with short ceils. Sample XI/6. x 50

Fig. 1.

Fig. 2.

Fig. 3.

Fig. 4, 5.

~g. 6 ,7 ,8 .

Fig . 9.

Fig. 10.

Fig. 11.

Fig. 12.

Permocalculus irenae ELLIOTT, 1958 - schr~iger L~agsschnitt. Probe XI/12,3. x 52,5

Arabicodium sp. - L~gsschnitt eines teilweise ausgelOsten Exemplares mit kortikale R0hrchen. Probe XI/7,1. x 42

Arabicodium aegagrapiloides ELLIO'IT, 1957 - schr~iger Horizonlalschnitt mit zentralen und kortikalen RShrchen. Probe XI/4,3. x 26,2

Trinocladus sp., beide mit ausgel~3sten und mikritisierten Prim~rzweigen und Stamm; Sekund~- und Terti~'zweige sind gut sichtbar: Fig. 4.: Schrager Schnitt eines verdriickten Individuums. Probe XI/7,2. x 55,5; Fig. 5.: Nahezu horizontaler Schnitt. Probe XI/7,2. x 42,2

Verschiedene Schnitflagen yon Cylindroporella sugdeni ELLIOT, 1957: Fig. 6.: l_~gsschnitt. Probe XI/12,1. x 35; Fig. 7.: Horizontalschnitt. Probe XI/ 12,3. x 46; Fig. 8.: Zentraler Langsschnitt. Probe XI/12,2. x 52

MarineUa lugeoni PFENDER, 1939 - kugelftirmige Kolonie. Probe XI/17. x 37

Trinocladus tripolitanus RAINER, 1922 - horizontaler Schnitt. Probe XI/5,2. x 46

Parachaetetes cf. hadhramautensis ELLIOTT, 1959 - sch~ger Schnitt eines rekristallisierten Thallus mit gebogenen Zellreihen. Probe XI/11. x 20

Kymalithon belgicum (FOSLIE) LEMOINE & EMBERGER, 1967 - diinner Hypothallus (unten) und dicker Perithallus mit kurzen Zellen. Probe XI/6. x 50

TAFEL 19

94

P l a t e Benthic foraminifera from the Late Aptian/Early Cenomanian limestones (Gebel Maghara, Sinai/Egypt)

Benthische Foraminiferen der Oberapt/Untercenoman Kalke (Gebel Maghara, SinaiL~gypten)

Fig. 1, 2, 3.

Fig. 4.

Fig. 5, 6.

Fig. 7, 8.

Fig. 9, 10.

Fig. 11.

Fig. 12.

Fig. 13.

Different sections of Dictyoconus algerianus CHERCHI & SCHROEDER, 1982: Fig. 1.: Almost axial section of a high, conical test. Dish-like chambers with the typical convex base. Sample XI/16,1. x 22.7; Fig. 2.: Detail of an axial section with well developed and alternating pillars. Sample XI/16,1. x 53; Fig. 3.: Oblique section, showing the vertical partitions of the marginal zone (Arrows). Sample XI/16,2. x 42.4

O. (M.) texana (ROEMER, 1849) - axial section of a juvenile individual with embryonic apparatus. Sample XI12. x 96

O. (M.) subconcava LEYMERIE, 1878: Fig. 5.: Axial section of a juvenile individual. Sample XI/7. x 79.4; Fig. 6.: Axial section of the embryonic apparatus. Sample XI/7. x 53.8

O. (M.) aperta (ERMAN, 1854): Fig. 7.: Subaxial section. Sample XI/5. x 32.5; Fig. 8.: Axial section (slightly oblique) showing the wide embryonic apparatus with the compressed proloculus in the centre. Note the anastomosing partitions (arrows) in the deuteroconch (above) and the subembryonic area (below). Sample XI/5. x 42.8

Cuneolina gr. pavonia d'ORBIGNY, 1839: Fig. 9.: subequatorial section with large proloculus and horizontal, subepidermal partitions (arrow). Sample XI/3. x 48; Fig. 10.: Oblique (almost equatorial) section with few horizontal partitions. Sample XI]16. x 53.6

Dicyclina sp. - axial (slightly oblique) section showing secondary partitions. Sample XI]16. x 30

Sabaudia minuta HOFKER, 1965, subaxial section. Sample XI/1,1. x 151

Nezzazata cf. simplex OMARA, 1956 - subequatorial and axial/oblique sections. Sample XI/3. x 33.3

Fig. 1, 2, 3.

Fig, 4.

Fig. 5,6.

Fig. 7, 8.

Fig. 9, 10.

Fig. 11.

Fig. 12.

Fig. 13.

Verschiedene Schnitflagen yon Dyctyoconus algerianus CHERCHI & SCHROEDER, 1982: Fig. 1.: Nahezu axialer Schnitt durch ein hohes, konisches Geh~iuse. Schfisself/Srmige Kammem mit der typisch konvexen Basis. Probe XI/16,1. x 22,7; Fig. 2: Detail eines Axialschnittes mit gut entwickelten, alternierend stehenden Pfeilem. Probe XI/16,1. x 53. Fig. 3. Schr~lger Schnitt, tier die vertikalen Teilungen der Randzone zeigt (Pfeile). Probe XI/16,2. x 42,4

O. (M.) texana (ROEMER, 1849) - Axialschnitt einer juvenilen Form mit den Embryonalkammem. Probe XI/12. x 96

O. (M.) subconcava LEYMERIE, 1878: Fig. 5.: Axialschnitt einer juvenilen Form. Probe XI/7. x 79,4; Fig. 6.: Achsialschnitt der Embryonalkammern. Probe XI/'7. x 53,8

O. (M.) aperta (ERMAN, 1854): Fig. 7.: Subaxialer Schnitt. Probe XI/5. x 32,5; Fig. 8.: Axialschnitt (leicht schrag), der den weiten Embryonalapparat mit dem verdriickten Proloculus im Zentrum zeigt. Verzweigte Zwischenwiinde (Pfeile) im Deuteroconch (oben) und im Subembryonalbereich (unten). Probe XI/5. x 42,8

Cuneolina gr. pavonia D'ORBIGNY, 1839: Fig. 9.: Subiiquatorialer Schnitt mit groBem Proloculus und horizontalen, subepidermalen Zwischenwanden (Pfeil). Probe XI/3. x 48; Fig. 10.: Schrilge (fast axiale) Schnittlage mit einigen horizontalen Zwischenw~den. Probe XI/16. x 53,6

Dicyclina sp. - axialer (leicht schriiger) Schnitt mit sekund,~ren Zwischenw~nden. Probe XI/16. x 30

Sabaudia minuta HOFKER, 1965, subaxiater Schnitt. Probe XUI,1. x 151

Nezzazata cf. simplex OMARA, 1956 - subitquatorialer and axial/schr~ger Schnitt. Probe XI/3. x 33,3

TAFEL 20

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