ORIGINAL PAPER

Palynostratigraphy and palaeoenvironmental significanceof the Cretaceous palynomorphs in the Qattara Rim-1X well,North Western Desert, Egypt

Maher I. El-Soughier & Amr S. Deaf & Magdy S. Mahmoud

Received: 12 February 2013 /Accepted: 15 April 2013# Saudi Society for Geosciences 2013

Abstract Palynological and palynofacies analyses werecarried out on some Cretaceous samples from the QattaraRim-1X borehole, north Western Desert, Egypt. Therecorded palynoflora enabled the recognition of two infor-mal miospore biozones arranged from oldest to youngest asElaterosporites klaszii-Afropollis jardinus AssemblageZone (mid Albian) and Elaterocolpites castelainii–Afropollis kahramanensis Assemblage Zone (late Albian–mid Cenomanian). A poorly fossiliferous but however, dat-able interval (late Cenomanian–Turonian to ?Campanian–Maastrichtian) representing the uppermost part of the stud-ied section was also recorded. The palynofacies and visualthermal maturation analyses indicate a mature terrestriallyderived organic matter (kerogen III) dominates the sedi-ments of the Kharita and Bahariya formations and thus thesetwo formations comprise potential mature gas source rocks.The sediments of the Abu Roash Formation are mostlydominated by mature amorphous organic matter (kerogenII) and the formation is regarded as a potential mature oilsource rock in the well. The palynomorphs and palynofaciesanalyses suggest deposition of the clastics of the Kharita andBahariya formations (middle Albian and upper Albian–mid-dle Cenomanian) in a marginal marine setting underdysoxic–anoxic conditions. By contrast, the mixed clastic-carbonate sediments of the Abu Roash Formation (upperCenomanian–Turonian) and the carbonates of the KhomanFormation (?Campanian–Maastrichtian) were mainly depos-ited in an inner shallow marine setting under prevailing

suboxic–anoxic conditions as a result of the late Cenomanianand the Campanianmarine transgressions. This environmentalchange from marginal to open (inner shelf) basins reflects thevertical change in the type of the organic matter and itscorresponding hydrocarbon-prone types. A regional warmand semi-arid climate but with a local humid condition devel-oped near/at the site of the well is thought to have prevailed.

Keywords Cretaceous . Palynostratigraphy . Palynofacies .

Palaeoecology . North western Egypt

Introduction

The northern part of the Western Desert, where the QattaraRim-1X borehole was drilled (Fig. 1), lies within the Un-stable Shelf Province described by Said (1962) for northernEgypt. The unstable province encompasses threeSubprovinces: the northern Western Desert, the EasternDesert, and northern Sinai. This vast unstable area wastectonically active during most of its geological history,and Paleozoic–early Cenozoic subsidence and basin differ-entiation to uplift and basin inversion of different areas ofthe north Western Desert took place (Hantar 1990). The areaof the present study at the northern rim of the QattaraDepression seems to have been affected by the latestTuronian and the post Santonian tectonics (Amoco 1992)that have affected other areas of the north Western Desert(Meshref 1990; Guiraud and Bosworth 1999; Guiraud et al.2001). Topographically, the north Western Desert is a simpleplain consisting of an Eocene–Miocene carbonate blanket,covered at some areas with Pliocene and Quaternary sedi-ments and overlies tectonically affected Paleozoic–lowerCenozoic rocks. This plain dips gently toward the sea andis cut in its western part by the Qattara Depression, SiwaOasis, and Wadi Natrun hollow, with the Abu Roash folded

M. I. El-Soughier (*)Faculty of Science, Geology Department, Aswan University,Aswan 81528, Egypte-mail: miabdelrahim@yahoo.com

A. S. Deaf :M. S. MahmoudFaculty of Science, Geology Department, Assiut University,Assiut 71516, Egypt

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area, the south-eastern unstable part of the Western Desert,possessing only a few highs (Hantar 1990). Cretaceousrocks are exposed in central Western Desert, southern East-ern Desert, along the Red Sea coast, and in north Sinai, andare only found as subsurface units in the north WesternDesert at great depths of wells drilled for hydrocarbons(Kerdany and Cherif 1990).

The Cretaceous strata in the north Western Desert can bedifferentiated into two main facies, a Lower Cretaceous con-tinental to shallow marine facies and an Upper Cretaceousmarine shale and carbonate facies (Said 1990). Deposition ofthe Lower Cretaceous (Aptian–Albian) rocks was mainlyaffected by synsedimentary tectonics related to the movementof the African plate towards Laurasia—related to the openingof the Atlantic Ocean—and to the opening of the East Med-iterranean Basin (Meshref 1990; Guiraud et al. 2001). Sedi-mentation of the Alamein Dolomite Formation occurredduring Aptian marine transgression episode related to theglobal sea level rise (Said 1990; Guiraud et al. 2001). How-ever, the Albian Kharita Formation was deposited during aregressive phase, which is reflected in the accumulation ofshallow marine clastics. Cenomanian sedimentation seems tohave been also affected by syndepositional subsidence related

to the Neotethyan rifting, which occurred across the entirenorthern African plate (El Zarka 1983; Meshref 1990). As aresult, a late Cenomanian marine transgression covered thenorth Western Desert and deposition of shallow marine clas-tics of the lower Bahariya Formation ended with deposition ofthe upper Bahariya marine carbonate unit (Kerdany andCherif 1990, Said 1990). Fully marine conditions prevailedover a large part of northern Egypt during the Turonian andthe mainly carbonate Abu Roash Formation was accumulated(Hantar 1990). A Coniacian marine transgression occurredafter a late Turonian uplift, and as a result, another carbonateunit of the B and C members of the Abu Roash Formationwere deposited. Regression took place again by the Santonianand is represented by deposition of mixed, clastics-carbonatesof the “A” member of the Abu Roash Formation. However,the Campanian–Maastrichtian time witnessed another trans-gression cycle and deposition of a thick chalky limestone tosnow-white chalk sequence of the Khoman Formation tookplace (Said 1990).

Egyptian Cretaceous rocks have been one of the maintargets of oil exploration since 1939 (Barakat et al. 1987)and a large number of deep boreholes have been drilled.Palynological work was initiated in Egypt in the 1960s (e.g.

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Helal 1965, 1966). Since the early 1980s much attention hasbeen paid to the stratigraphy of the northern part of theWestern Desert and several useful palynological studies havebeen published. From 1990s onward, another dimension wasadded to Egyptian palynology, namely the application ofpalynomorphs to palaeoenvironmental reconstruction (e.g.Omran et al. 1990; Schrank and Ibrahim 1995; Ibrahim1996, 2002; Mahmoud and Moawad 2000, 2002; Mahmoudand Deaf 2007; El-Soughier et al. 2010; El Beialy et al. 2011).Published palynological work on the Cretaceous of theQattara Depression and its surrounding area is still incom-plete. Only the work of Ibrahim (1996, 2002) on the Ghazalat-1 well provides useful information. In order to shed more lighton this part of the north Western Desert, the current projectwas chosen to contribute to the palynostratigraphy,palynofacies and palaeoenvironmental interpretations of theupper lower–upper Cretaceous successions penetrated by theQattara Rim-1X borehole.

Lithostratigraphy

It is important to mention that the sediments studiedwere not differentiated into formations by Amoco(1992). Here, a tentative identification of the Cretaceousformations based only on lithological characteristics wasnot possible, because the lower Cretaceous of the north-ern Desert of Egypt mainly consists of a thick sand-stone unit, which lacks marker beds that would help information differentiation. Therefore, the lithological de-scription and preliminary age dating provided byAmoco (1992) in the composite log combined with thepalynologically based age dating derived from a latersection (“Palynostratigraphy” section), have been usedto recognise different formations. Description of theCretaceous formations in the Stratigraphic Lexicon ofEgypt (Hermina et al. 1989) along with the descriptionprovided by Hantar (1990) for the same formations hasbeen also consulted. As a result, the formations identi-fied are suggested to be from oldest to youngest asfollows:

Kharita Formation

This formation was described by El-Gezeery et al.(1972). Its type section is located between 2,501 and2,890 m of the Kharita-1 well. It consists mainly of fineto coarse-grained sandstones and minor shale intercala-tions, and is conformably overlain by the BahariyaFormation. An Albian age and a high-energy shallowmarine environment were suggested for the formation(Hantar 1990; Kerdany and Cherif 1990). However,palynological work (e.g. Mahmoud and Moawad 1999;

Ibrahim 2002; El Beialy et al. 2011) on the formationindicated a mid Albian–early Cenomanian age and de-position in nearshore to shallow marine shelf settings.In the Qattara Rim-1X borehole, the studied section(7670–3950 ft, 2338–1204 m) was identified by Amoco(1992) as “Alamein Formation” and “Albian andCenomanian Clastics”. In our work, this sample interval waslitho- and bio-stratigraphically identified as the Kharita For-mation and was dated as mid–late Albian age.

Bahariya Formation

Said (1962) first described this rock unit, but its typesection was identified by Akkad and Issawi (1963) asbeing 173 m (567 ft) thick at Gebel El-Dist, north ofthe Bahariya Oasis, Western Desert. This formation iscomposed of alternating sandstone and shale beds occa-sionally topped by limestone horizons. The BahariyaFormation rests conformably over the Kharita Formationand has also a conformable boundary with the overlyingAbu Roash Formation. This formation of a Cenomanianage (Norton 1967) and is interpreted to have beendeposited in shallow marine to fluviomarine–deltaic set-tings (Said, 1990). Palynological investigations ofSchrank and Ibrahim (1995), Ibrahim (2002) and ElBeialy et al. (2011) on the formation indicate early–mid Cenomanian age and support the above-mentioneddepositional environments. In the studied borehole,Amoco (1992) assigned “Cenomanian Clastics” to thesection from 5,500–5,010 ft (1,676–1,527 m), which werecognise here as the Bahariya Formation and suggesteda mid Cenomanian age for the section.

Abu Roash Formation

This formation was first described by Beadnell (1902)and later ranked as a formation by Norton (1967). Itstype locality is the Abu Roash-1 well, northern WesternDesert, the type section reaching up to 217 m (712 ft)thick. It is mainly composed of a limestone sequencewith occasional interbeds of shale and sandstone, and issubdivided into seven members labelled G-A from bot-tom to top. The formation is conformably overlain bythe Khoman Formation and ranges in age from lateCenomanian (member G) to Turonian-Santonian (A–Fmembers). It is believed to have been deposited in anopen shallow marine shelf setting apart from unit G,which is inferred to have been of lagoonal origin in thesouth (Hantar, 1990). Both litho- and palynostratigraphicdata from depth interval (5,000–4,000 ft, 1,524–1,219 m) in the Qattara Rim-1X best correlates withthe Abu Roash Formation and a late Cenomanian–Turonian age is assigned to the sample interval.

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Khoman Formation

It is composed of chalky limestone to snow-white chalkwith occasional thin shale beds at its base (Hantar 1990).The Khoman Formation overlies conformably the AbuRoash Formation and unconformably in some basins. It isconsidered to be of a Campanian–Maastrichtian age and tohave been deposited in open marine outer shelf environ-ments (Hantar 1990; Kerdany and Cherif 1990).

Material and methods

The samples investigated are 23 ditch-cutting samples collect-ed from the Qattara Rim-1X borehole, from 7,670 to 3,950 ft(2338–1204 m), and only 12 samples were found productive.The borehole was drilled in the north Western Desert of Egypt(Fig. 1) at the northern margin of the Qattara Depression (Lat.30° 37′ 01″ N and Long. 28° 16′ 31″ E) by Amoco companyin (1992). The stratigraphy and location of the productivesamples are shown in Fig. 1. The sediments are composedmainly of limestone, shale and thick sandstones. The samplematerial was processed at the Nanjing Institute of Geologyand Palaeontology, Chinese Academy of Sciences (NIGPAS),using standard HCl/HF processing techniques (e.g. Wood etal. 1996). They were not subjected to any ultrasonic or oxida-tion treatment. For qualitative and quantitative studies, two tofive permanent slides were prepared using glycerine jelly as amounting medium. The slides were examined using OLYM-PUS CX21FS1 microscope. Photomicrographs of selectedspores, pollen and dinoflagellate cysts are shown on Plates 1,2 and 3. The samples and organic residues are housed in thecollections of the NIGPAS. The microscope slides, primarydata and figured material are housed in the collections of theGeology Department, Aswan Faculty of Science, Aswan,Egypt.

Palynostratigraphy

The material analysed yielded well-preserved and rela-tively diverse assemblages of sporomorphs and dinofla-gellate cysts. The semi-quantitative distribution of alltaxa recorded herein is arranged according to theirhighest appearance datums (Fig. 2). The age assessmentare based on range of index palynomorph taxa and oncorrelation with well age-constrained, simultaneous re-gional and interregional palynofloral assemblages iden-tified in the Albian–Cenomanian Elaterates Province ofHerngreen et al. (1996). Ranges of the sporomorphshave been mainly used in the age assessments, withavailable ranges of the dinoflagellate cysts, since markerspecies of the latter are missing.

Palynozone I (mid Albian) Elaterosporites klaszii-Afropollisjardinus assemblage zone

Samples 1–5 From depth interval 7,670–6,160 ft (∼2,338–1,878 m).

Definition From the first appearance datum (FAD) ofElaterosporites klaszii to the FAD of Afropollis kahramanensisand Elaterocolpites castelainii.

Remarks The palynoflora of this zone is mainly dominatedby long-ranging pteridophyte spore and gymnosperm pollengrains; only one gymnospermous index pollen grain appearsin the zone. The angiosperm pollen grains are representedby fewer genera (mainly reticulate mono- and tricolpatepollens) but include two index taxa. Most of the dinoflagel-late cysts are long-ranging.

Age assessment and correlation This biozone is characterisedby the presence of a few of the Albian–Cenomanian diagnosticmiospores. Elaterosporites klaszii is widely accepted as a midAlbian–mid Cenomanian marker taxon in the Albian–Cenomanian Elaterates Phytogeographic Province ofHerngreen et al. (1996) and occurs in samples 1–5. In WestAfrica, E. klaszii has been recorded in Senegal and the IvoryCoast from rocks of mid Albian–mid Cenomanian age (Jardinéand Magloire 1965; Jardiné 1967). In Brazil and Colombia, itwas found to range through rocks dated on the basis of forami-nifera as mid Albian to mid Cenomanian (Müller 1966;Herngreen 1973; Herngreen and Jimenez 1990). Afropollisjardinus is known to have an unequivocally early Albian–midCenomanian range in the Albian–Cenomanian Elaterates Phy-togeographic Province. In West Africa, it was recorded inSenegal by Jardiné and Magloire (1965) as S. CI. 156 IncertaeSedis from foraminifera-dated rocks of early Albian–midCenomanian age. Later in the Senegal reference section ofAfropollis, Doyle et al. (1982) recorded A. jardinus from

Plate 1 Spores (1–10) and pollen (11–21) of the Qattara Rim-1Xborehole. All figures are ×600. 1 Deltoidospora spp., 7,670 ft., diam-eter 68 μm; 2 Concavissimisporites punctatus, 7,380 ft., diameter65 μm; 3 Punctatisporites sp., 7,670 ft., diameter 62 μm; 4Balmeisporites holodictyus, 7,380 ft., diameter 60 μm ; 5Pilosisporites sp., 6,970 ft., diameter 66 μm; 6 Crybelosporitespannuceus, 5,330 ft., diameter 73 μm; 7 Cicatricosisporites sinuous,6,970 ft., diameter 74 μm; 8 Cicatricosisporites orbiculatus, 6,970 ft.,diameter 76 μm; 9 Duplexisporites generallis, 7,380 ft., diameter78 μm; 10 Murospora florida, 6,160 ft., diameter 77 μm; 11Callialasporites dampieri , 6,970 ft., diameter 75 μm; 12Inaperturopollenites sp., 7,380 ft., diameter 82 μm; 13 Araucariacitesaustrallis, 6,160 ft., diameter 85 μm; 14 Classopollis sp., 5,660 ft.,diameter 68 μm; 15 Classopollis classoides, 6,970 ft., diameter 59 μm;16 Classopollis torosus, 5,330 ft., diameter 63 μm; 17 Ephedripitessp., 5,660 ft., diameter 88 μm; 18 Ephedripites jansonii, 5,660 ft.,diameter 90 μm; 19 Cingulatipollenites aegyptiaca, 6,530 ft., diameter68 μm; 20 Classopollis brasiliensis, 4,670 ft., diameter 63 μm; 21Ephedripites strigatus, 6,970 ft., diameter 98 μm

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micropalaeontology-dated rocks of early Albian–midCenomanian age. In northeast Africa, specifically in Egypt, thissame species was recorded from palynologically dated lowerAlbian–middle Cenomanian rocks (e.g. El Beialy 1994;Schrank and Ibrahim 1995; Mahmoud and Moawad 2002). Innorth South America, Afropollis jardinus was recorded fromthe micropalaeontology-dated lower Albian–middleCenomanian strata of Brazil (Herngreen 1973, 1975) andAlbian of Peru (Brenner 1968), and in Colombia fromammonite-dated lower Albian-lower Cenomanian rocks(Herngreen and Jimenez 1990). Appearing in the upper part(Sample 5) of this biozone is Cretacaeiporites densimurus, ataxon that was first described by Schrank and Ibrahim (1995)from Egyptian foraminifera-calibrated rocks of early–midCenomanian age, with its FAD was later extended byIbrahim (2002) downward into the palynologically datedlate Albian of Egypt. Therefore, the presence ofCretacaeiporites densimurus in Palynozone I is attribut-ed to caving until an independent calibration of thisdownward range is provided.

In terms of dinoflagellate cysts, the current palynozonewitnesses the presence of few species of generally anAlbian–Cenomanian aspect. Florentinia berran occursthroughout the zone. It was recorded in the southern TethyanRealm from the dinoflagellate-dated Albian–earlyCenomanian of Morocco and NE Libya (Below 1982,1984; Uwins and Batten 1988) and from the palynologicallydated late Albian–mid Cenomanian of Egypt (Schrank andIbrahim 1995; Ibrahim 2002; El Beialy et al. 2010).Florentinia mantellii also appears throughout the zone. Itwas recorded in the northern Tethyan Realm fromammonite-dated Aptian–early Cenomanian sequences inSE France (Davey and Verdier 1973; Davey and Verdier1974) and from micropalaeontologically calibrated Albian

strata of central Italy (Torricelli 2006). An Albian–midCenomanian range for Florentinia mantellii in the southernTethyan Realm was indicated by some sequences of northEgypt (e.g. Schrank and Ibrahim 1995; Ibrahim 2002).Florentinia radiculata could be another important Albianspecies, having been recorded from early–mid Albian strataof the Paris Basin, France (Davey and Verdier 1971), themicropalaeontologically calibrated late Albian of SE Franceand central Italy (Davey and Verdier 1973; Torricelli 2006),and the late Albian of Egypt (Schrank and Ibrahim 1995).

Regional correlation shows that zones described fromthe Egyptian north Western Desert namely: the Zone III(mid Albian) of Schrank and Ibrahim (1995) in theKRM-1 well, and Zone 2 (mid Albian) of Ibrahim(1996) in the GTX-1 well, greatly resemble the currentzone. From an interregional context, the Sequence X(mid Albian) of Jardiné and Magloire (1965) in theSenegal Basin, and the uppermost part (samples 16–20) of Zone I (early–mid Albian) of Herngreen (1973)in the Maranhão Basin, Brazil, are also correlatable toPalynozone I.

A mid Albian age is therefore assigned to the currentzone based on the presence of the mid Albian diagnos-tic species Elaterosporites klaszii and the FAD of thelate Albian gymnosperm marker pollen Elaterocolpitescastelainii appearing in the overlying Sample 6. An agethat is also supported by correlating Palynozone I to itscontemporaneous regional and interregional biozones.

Palynozone II (late Albian–mid Cenomanian)Elaterocolpites castelainii–Afropollis kahramanensisassemblage zone

Samples 6 and 7 From depth interval 5,660–5,330 ft(∼1,725–1,625 m).

Definition From the FAD of Elaterocolpites castelainii andAfropollis kahramanensis to the last appearance datum(LAD) of Classopollis spp., Elaterocolpites castelainii andAfropollis kahramanensis.

Other last appearance datums that characterise top of thisbiozone are Afropollis jardinus, Cretacaeiporites densimurus,and Elaterosporites klaszii.

Remarks The palynofloral assemblage of this interval dif-fers from the underlying one, as genera of the pteridophytespores show great decrease in abundance, but the zone ischaracterised by the appearance of another elaterate indexpollen grain. Less angiosperms as well as dinoflagellatecysts are recorded in this zone.

Age assessment and correlation Elaterocolpites castelainiiis an important late Albian–mid Cenomanian elaterate

Plate 2 Angiosperm (1–16) and dinoflagellate cysts (17–23) of theQattara Rim-1X borehole. Magnifications are ×600 (1–5, 12–13, 17–23) and ×1,000 (6–11, 14–16). 1 Retimonocolpites sp., 7,670 ft., di-ameter 85 μm; 2 Afropollis kahramanensis, 5,660 ft., diameter 80 μm;3 Afropollis jardinus, 5,330 ft., diameter 68 μm; 4 Cretacaeiporitesdensimurus, 7,670 ft., diameter 85 μm; 5 Elaterosporites klaszii,5,660 ft., diameter 56 μm; 6 Echitriporites sp., 4,050 ft., diameter57 μm; 7 Triporites sp., 4,050 ft., diameter 54 μm; 8 Rousea spp. cf.delicipollis, 5,660 ft., diameter 56 μm; 9 Lakiapollis ovatus (Cenoszoicpollen), 3,950 ft., diameter 56 μm; 10 ?Varispintriporites sp., 3,950 ft.,diameter 57 μm; 11 Pseudoculopollis sp., 3,950 ft., diameter 58 μm; 12Elaterocolpites castelainii, 5,330 ft., diameter 48μm; 13 Foveotricolpitesgigantoreticulats, 5,660 ft., diameter 76 μm; 14 Spinizocolpites sp.,3,950 ft., diameter 68 μm; 15 Longapertites sp., 3,950 ft., diameter65 μm; 16 Triporites sp., 3,950 ft., diameter 46 μm; 17 Circulodiniumdistinctum, 5,660 ft., length 64 μm; 18 Dinopterygium tuberculatum,6,160 ft., diameter 64 μm; 19 Odontochitina porifera, 4,770 ft., length64 μm; 20 Downiesphaeridium aciculare, 6,970 ft., diameter 52 μm; 21Sepispinula huguoniotii, 4,770 ft., diameter 52 μm; 22 Palaeoperidiniumcretaceum, 4,770 ft., length 72 μm, breadth 68 μm; 23 Subtillisphaerasenegalensis, 7,380 ft., length 62 μm

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Plate 3 Dinoflagellate cysts of the Qattara Rim-1X borehole. Allfigures are x600. 1 Cyclonephelium vannophorum, 7,670 ft., length62 μm; 2 Downisphaeridium aciculare, 5,660 ft., diameter 60 μm; 3Dinopterygium cladoides, 4,770 ft., length 60 μm; 4 Spiniferitesramosus, 6,530 ft., diameter 59 μm; 5 Oligosphaeridium complex,4,190 ft., diameter of body 50 μm, length of processes 26 μm; 6Spiniferites multibervis, 4,050 ft., diameter 59 μm; 7 Impagidiniumsp., 4,770 ft., diameter 64 μm; 8 Systematophora areolata, 6,970 ft.,diameter 56 μm; 9 Spiniferites multibervis, 4,050 ft., diameter 58 μm;10 Cannosphaeropsis utinensis, 4,050 ft., diameter 56 μm; 11Surculosphaeridium longifurcatum, 4,190 ft., diameter of body

52 μm, length of processes 24 μm; 12 Florentinia cooksoniae,4,190 ft., diameter of body 58 μm, length of processes 22 μm; 13Oligosphaeridium pulcherrimum, 4,050 ft., diameter of body 58 μm,length of processes 25 μm; 14 Florentinia radiculata, 6,970 ft., diam-eter of body 54 μm, length of processes 24 μm; 15 Coroniferatubulosa, 6,530 ft., Overall length 44 μm, length of processes10 μm; 16 Florentinia barren, 6,160 ft., diameter of body 42 μm,length of processes 22 μm.; 17 Palynofacies A, sample 5,560 ft.; 18Palynofacies B, 4,050 ft. Abbreviation for phytoclasts andpalynomorphs; AOM amorphous organic matter, S spores, W. brownwood, C Cuticles, BDB: black debris

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index form in the Elaterates Province. In Senegal, E.castelainii was documented to range in foraminiferallydated rocks from the late Albian to the mid Cenomanian(Jardiné and Magloire 1965; Jardiné 1967). In Brazil,the same species was also recorded from rocks dated bymeans of foraminifera as being of late Albian–midCenomanian age (Herngreen 1973; Herngreen andJimenez 1990). At southern Switzerland, a region be-longs to the Albian–Cenomanian Elaterates Province; E.castelainii was also recorded by Hochuli (1981) fromforaminifera-dated late Albian strata. Afropolliskahramanensis is a potential regional key angiospermtaxon. It was first described by Schrank and Ibrahim(1995) from the benthic foraminifera-calibrated early–mid Cenomanian of Egypt. Later, Ibrahim (2002)recorded A. kahramanensis from other plankticforaminifera-dated rocks of Egypt, also of early–midCenomanian age. A regional downward extension ofthe species range into the proposed late Albian of thecurrent zone is not contradictory to its known early–midCenomanian range, because the Pollen PO-304 de-scribed by Lawal and Moullade (1986) from the paly-nologically dated late Albian–mid Cenomanian of NENigeria was regarded by Schrank and Ibrahim (1995) as

identical to their new species. The same downwardrange of A. kahramanensis into a palynologically datedlate Albian–early Cenomanian sediments of the AbuTunis 1× borehole in the north Western Desert was alsorecorded by Deaf et al. (2013), which would rathersupport a late Albian first appearance datum for thespecies in Egypt. Cretacaeiporites densimurus, whichis known to have its LAD confined to the midCenomanian of Egypt, occurs in the uppermost part ofPalynozone II. Termination of Afropollis jardinus atSample 7 is another bioevent that is taken here to markthe upper boundary of the mid Cenomanian. In Senegal,Jardiné and Magloire (1965) recorded A. jardinus (asIncertae Sedis S. CI. 156) in their foraminifera-datedSequences VIIa and VIIb of the mid Cenomanian age,similarly in the same region, Doyle et al. (1982) notedthat A. jardinus declined greatly in the late Albian–earlyCenomanian and disappeared completely in the midCenomanian. Egyptian stratigraphic records also showAfropollis jardinus as having its LAD at topmost in-tervals of foraminifera-dated zones of early–midCenomanian age; these are Zone V of Schrank andIbrahim (1995) and Assemblage Zone “B” of Ibrahim(2002). Elaterosporites klaszii also has its uppermost

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3

12

Abundant (>50 grains)

Common (>10 grains)

Present (2-10 grains)

Single grains

Del

toid

osp

ora

spp

.

Trip

lan

osp

ori

tes

sp.

Cry

bel

osp

ori

tes

pan

nu

seu

s

Mu

rosp

ora

flo

rid

a

Mu

rosp

ora

sp.

Du

ple

xisp

ori

tes

gen

eral

lis

Bal

mei

spo

rite

sh

olo

dic

tyu

s

Tod

isp

ori

tes

maj

or

Tod

isp

ori

tes

sp.

Cic

atri

cosi

spo

rite

ssp

p.

Pilo

sisp

ori

tes

sp.

Bal

mei

spo

rite

ssp

.

Mat

on

isp

ori

tes

sp.

Pu

nct

atis

po

rite

ssp

.

Co

nca

viss

imis

po

rite

sp

un

ctat

us

Cic

atri

cosi

spo

rite

so

rbic

ula

tus

Ver

ruco

sisp

ori

tes

sp.

Co

nca

visp

ori

tes

sp.

Cic

atri

cosi

spo

rite

ssi

nu

ou

s

Lae

vig

ato

spo

rite

ssp

.

Spores

Inap

ertu

rop

olle

nit

essp

p.

Sp

her

ipo

llen

ites

sp.

Cyc

ado

pit

essp

.

Ara

uca

riac

ites

aust

ralli

s

Ep

hed

rip

ites

sp.

Cla

sso

po

llis

toro

sus

Cla

sso

po

llis

sp.

Ep

hed

rip

ites

stri

gat

us

Cal

liala

spo

rite

sd

amp

ieri

Cin

gu

lati

po

llen

ites

aeg

ypti

aca

Cla

sso

po

llis

bra

silie

nsi

s

Cla

sso

po

llis

clas

soid

es

Ep

hed

rip

ites

jan

son

ii

Gymanosperm

L.A

lbia

nM

. Cen

om

ania

n

L.C

eno

man

ian

-Tu

ron

ian

?Kh A

Kh

arita

Ela

tero

spo

rite

skl

aszi

i-A

fro

po

llis

jard

inu

sE

late

r.ca

stel

aini

i-A

fr.k

ahra

man

ensi

s

Bahar

iya

Poo

rly

foss

ilife

rous

inte

rval

Ab

uR

oas

h

?Cam-Ma

Fig. 2 Selected palynomorph ranges in the section examined of the Qattara Rim-1X

Arab J Geosci

occurrence in Sample 7, and its top range was documented tocoincident with end of the mid Cenomanian in Senegal andBrazil (Jardiné and Magloire 1965; Müller 1966; Jardiné1967; Herngreen 1973; Herngreen and Jimenez 1990). InEgypt, Elaterosporites klaszii shows the same scenario inindependently dated rocks of mid Cenomanian age (Schrankand Ibrahim 1995; Ibrahim 2002).

The phytoplanktons recoded in the present zone showno age inference to the late Albian–mid Cenomanian.Florentinia mantellii has its LAD in Sample 7; however,a Maastrichtian range of the species was documented insome Egyptian records (e.g. Schrank and Ibrahim 1995).Florentinia berran appears throughout the biozone andcontinues upward into the next one.

Study of the Egyptian late Albian–mid Cenomanianbiozonation shows that Zones IV–Vof Schrank and Ibrahim(1995) in the KRM-1 well, and Zones “A” and “B” ofIbrahim (2002) in the AG-5 well, are greatly correlatableto the current zone. Zone 3 (early–mid Cenomanian) ofIbrahim (1996) in the GTX-1 well, only equates to the upperpart of Palynozone II. Interregionally, our proposed zoneresembles Zones II–III (late Albian–mid Cenomanian) ofHerngreen (1973) from Brazil, Sequences VIIb–IX (lateAlbian–mid Cenomanian) of Jardiné and Magloire (1965)from the Senegal Basin, and Zone I (late Albian–midCenomanian) of Lawal and Moullade (1986) from the upperBenue Basin, northeast Nigeria.

Based on the stratigraphic range of the elaterate andangiosperm index taxa discussed above and the biozonecorrelation, a late Albian–mid Cenomanian age is suggestedfor Palynozone II.

Poorly fossiliferous interval (late Cenomanian–Turonianto Campanian–Maastrichtian)

Samples 8–12 From depth interval 4,770–3,950 ft (∼1,454–1,204 m).

Definition From just above the LAD of Elaterocolpitescastelainii and Afropollis kahramanensis to the top of thestudied section.

Remarks The palynoflora of this zone exhibit lower abun-dance of terrestrial palynomorphs than those recorded in theprevious one, and in contrast, dinoflagellate cysts dominatethe fossil assemblage.

Age assessment and correlation The occurrence ofTriporites sp. in Sample 9 suggests a mid–lateCenomanian age for this sample. Triporate pollensappeared in the micropalaeontologically dated mid–lateCenomanian of Senegal and NE Nigeria (Jardiné andMagloire 1965; Lawal and Moullade 1986) and Brazil(Herngreen 1973). Foraminifera-dated strata of Egypt

4000

5000

6000

7000

Mid

dle

Alb

ian

8000

10

1

98

2

11

7

5

6

4

3

12

Abundant (>50 grains)

Common (>10 grains)

Present (2-10 grains)

Single grains

Lo

ng

aper

tite

ssp

.

AngiospermDinoflagellate cysts

Ech

itri

po

rite

str

ian

gu

lifo

rmis

Pse

ud

ocu

lop

olli

ssp

.Tr

ipo

rite

ssp

.L

akia

po

llis

ova

tus

Tric

olp

oro

po

llen

ites

sp.

Sp

iniz

oco

lpit

essp

.S

cab

ratr

ipo

rite

ssi

mp

lifo

rmis

Lili

acid

ites

sp.

Afr

op

olli

sja

rdin

us

Ret

imo

no

colp

ites

vari

plic

atu

sR

etim

on

oco

lpit

essp

.C

reta

caei

po

rite

sd

ensi

mu

rus

Are

cip

ites

pu

nct

atu

sA

fro

po

llis

kah

ram

anen

sis

Ro

use

asp

.F

ove

otr

ico

lpit

esg

igan

tore

ticu

latu

sA

fro

po

llis

sp.

Ro

use

ad

elic

ipo

llis

Ro

use

asp

pcf

.del

icip

olli

sA

reci

pit

essp

.S

tella

top

olli

ssp

.

Ela

tero

spo

rite

skl

aszi

i

Ela

tero

colp

ites

cast

elai

niiEla

. Pol

len

Co

ron

ifer

ao

cean

ica

Flo

ren

tin

iaco

oks

on

iae

Do

wn

iesp

hae

rid

ium

acic

ula

reC

ann

osp

hae

rop

sis

uti

nen

sis

Olio

sph

aeri

diu

mco

mp

lex

Flo

ren

tin

iara

dic

ula

taC

oro

nif

era

tub

ulo

saIm

pag

idin

ium

sp.

Su

rcu

losp

hae

rid

ium

lon

gif

urc

atu

m

Cyc

lon

eph

eliu

msp

.

Sp

inif

erit

esra

mo

sus

Cle

isto

sph

aeri

diu

msp

.

Olig

osp

hae

rid

ium

sp.

Sp

inif

erit

esm

ult

ibre

vis

Sp

inif

erit

essp

.

Sep

isp

inu

lah

ug

uo

nid

ium

Od

on

toch

itin

ap

ori

fera

Od

on

toch

itin

ao

per

cula

taS

ub

tilis

ph

aera

sen

egal

ensi

sF

lore

nti

nia

ber

ran

Flo

ren

tin

iasp

.D

ino

pte

ryg

ium

clad

oid

esD

ino

pte

ryg

ium

tub

ercu

latu

mC

ircu

lod

iniu

md

isti

nct

um

Flo

ren

tin

iam

ante

llii

Su

bti

lisp

hae

rasp

.

Cyc

lon

eph

eliu

mva

nn

op

ho

rum

Pal

aeo

per

idin

ium

sp.

Sys

tem

ato

ph

ora

sp.

Sys

tem

ato

ph

ora

areo

lata

Olig

osp

hae

rid

ium

pu

lch

erri

mu

m

Mar

ine

acri

tarc

h

Mic

rofo

ram

inif

eral

linin

gte

st

L.A

lbia

n-

M.C

en

om

.L

.C

en

om

an

ian

-Tu

ron

ian

?Kh A

Kh

arita

Ela

tero

spo

rite

skl

aszi

i-A

fro

po

llis

jard

inu

sE

late

r.ca

stel

aini

i-A

fr.k

ahra

man

ensi

sBah

ar.

Poo

rly

foss

ilife

rous

inte

rval

Ab

uR

oas

h

?C-M

Fig. 2 (continued)

Arab J Geosci

also indicated the same mid–late Cenomanian range ofthe triporates (Ibrahim and Schrank 1996; Ibrahim1996). Scabratriporites simpliformis appears in samples10 and 11, and it was recorded in Nigeria from strata ofCampanian–Maastrichtian age (Jan du Chene et al.1978; Agyingi 1993). In North West Egypt, S.simpliformis was found to range in foraminifera-calibrated rocks from the latest Turonian to earlyMaastrichtian (Schrank and Ibrahim 1995). Thus, sam-ples 10 and 11 can be regarded as of a late Turonian toMaastrichtian age. However, the presence of an uncon-formity surface above sample 11 would rather suggest alate Turonian age for samples 10 and 11. This is be-cause of the Laramide tectonic event, which causeduplift and basin inversion of the Qattara Ridge (the areaof study) and a few other basins in the north WesternDesert by the latest Turonian time and onward (Said1990). This unconformity was pronounced in many ba-sins of the north Western Desert, where the KhomanFormation (Campanian–Maastrichtian) frequently over-lies the partly eroded Turonian of the Abu Roash For-mation (Kerdany and Cherif 1990). In Sample 12 occursEchitriporites trianguliformis; an angiosperm pollen thatappeared in several independently dated Campanian–Maastrichtian rocks of Nigeria (Jan du Chene et al.1978; Lawal and Moullade 1986; Salami 1990). In theWest African countries such as Senegal, the IvoryCoast, Cameroon, and Gabon, the same Campanian–Maastrichtian range of E. trianguliformis was reported(Salard-Cheboldaeff 1990). Thus, the stratigraphic range ofEchitriporites trianguliformiswould probably suggest a Cam-panian–Maastrichtian age for Sample 12.

Dinoflagellate cysts in this samples interval show nobiostratigraphic significance as they have long ranges.Surculosphaeridium longifurcatum appears in samples 11and 12 but gives no age indication. It was recorded fromthe late Albian-Maastrichtian of Egypt (Schrank andIbrahim 1995). Cannosphaeropsis utinensis (Sample 12)was also recorded by Schrank and Ibrahim (1995) fromthe foraminifera-calibrated Maastrichtian of the AG-1 well,in the north Western Desert of Egypt. The paucity of pollenor dinoflagellate cyst index forms in this studied interval donot, however, contradict a late Cenomanian–Turonian agefor samples 8–11, and a ?Campanian–Maastrichtian age forSample 12.

Palynofacies and kerogen types

The palynofacies was defined by Combaz (1964) as the totalcomplement of acid-resistant particulate organic matter re-covered from sediments by palynological processing

techniques. The technique of palynofacies analysis is widelyused today as an important tool for the determination ofenvironments of deposition and for establishment of kero-gen types of possible petroleum source rocks (Tyson 1993;Batten 1996). The types of particulate organic matter iden-tified here are categorized as palynomorphs, phytoclasts (i.e.brown wood and cuticles), opaque phytoclasts (i.e. oxidizedor carbonized brownish-black to black woody tissues), andamorphous organic matter (AOM) according to Tyson(1995). Each counted palynofacies constituent was classi-fied in terms of rare (<3 %), present (3–10 %), common(>10 %), abundant (>40 %), very abundant (50–70 %), andextremely abundant (>90 %). Sediments of the Qattara Rim-1X well can be classified into two palynofacies types basedon the change in the percentages of each particulate organicmatter category as follows:

Palynofacies A (phytoclasts-dominated facies)

This palynofacies was scored from the middle Albian andupper Albian–middle Cenomanian (samples 1–7, 7,670–5,330 ft/∼2,338–1,625 m). It contains common to very abun-dant (30–53, avg. 45 %) phytoclasts and common (15–25,avg. 22 %) opaque phytoclasts (Fig. 3). AOM is the secondmost abundant constituent; it has common to abundant (15–45, avg. 27 %) percentages. In contrast, the palynomorphs hasthe least frequency and shows present (5–10, avg. 7 %) oc-currences. The plot of Palynofacies A in the ternary kerogendiagram of Tyson (1995) indicates a mainly kerogen III thatwas deposited in a marginal basin (Fig. 4), where AOM isdiluted by the high phytoclasts influx, but the prevailingdysoxic–anoxic conditions maintained preservation of com-mon to abundant AOM frequencies. Generally, the abundanceof the phytoclasts and the common occurrences of AOMsuggest a kerogen type III to II for Palynofacies A.

Palynofacies B (AOM-dominated facies)

This palynofacies was inferred from the upper Cenomanian–Turonian (samples 8–11, 4,770–4,050 ft/1,454–1,234 m) andthe ?Campanian–Maastrichtian (Sample 12, 3,950 ft/1,204 m).The extreme abundances (65–94, avg. 81 %) of AOM charac-terise this palynofacies. Here, a significant decrease in thephytoclasts frequencies in comparison to the previouspalynofacies is represented by its present to common (3–15,avg. 10 %) occurrences. Rare to mostly present (1–12, avg.6 %) frequencies of opaque phytoclasts and palynomorphs (2–8, avg. 4 %) were recorded in the palynofacies. The kerogendiagram suggests a kerogen type II for Palynofacies B that wasdeposited in a distal basin, where the sedimentation of AOMwas removed from active sources of terrestrial organic matter,and at which the enhanced reducing (suboxic–anoxic) condi-tions preserved these high percentages of AOM (Tyson 1993).

Arab J Geosci

The dominance of AOM over the terrestrially derived organicmatter suggests a kerogen type II for Palynofacies B.

Visual assessment of organic thermal maturation

Maturation is the process by which plants and other algalmaterial deposited in sediments are thermally decomposedto yield oil, natural gas and other products. Maturation isgoverned by both time and temperature, in which the samedegree of maturation can be attained at a low temperaturefor a long period of time as at a high temperature for a shortperiod of time (Oehler 1983). Several numerical scales,based on palynomorph colour, linked with phases of organicmaturation and petroleum generation were erected in the late1960s and onward by Correia (1967), Staplin (1969), Pear-son (1984), and Firth (1993) and others. This change incolour mirrors the thermal history of organic matter. Sourcerocks are naturally capable of generating and releasing hy-drocarbons in amounts to form commercial accumulations(Hunt 1979). Source rock potential of hydrocarbons in the

Fig. 4 Ternary kerogen diagram of Tyson (1993) and palynomorphplots of the Qattara Rim-1X

Age

Dept

h

Lithology

Sample

No.

4000

5000

6000

7000

8000

Mid

dle

Alb

ian

10

1

9

8

2

11

7

5

6

4

3

12

0 10 0 20 020 0 20 0 20 0 0

Palyno

morph

s

Opaqu

eph

ytocla

sts

Cuticle

s

Brown woo

d

Amorho

usOrg

anic

Matter

(AOM)

Palyno

facies

&

Assem

blage

chara

cteris

tics

B

A

Dominated by AOM (65-94%)

Opaque phytoclasts are poor (1-12%)

Brown wood and cuticles are poor (1-12%)

AOM are common (15-45%)

Opaque phytoclasts present (15-25%)

Brown wood common (30-53%)

L. A

lbia

n-M

Cen

om

an

ian

L.C

en

om

an

ian

-Tu

ron

ian

?Kh AK

har

ita

Ela

tero

spo

rite

skl

aszi

i-A

fro

po

llis

jard

inu

sE

late

r.ca

stel

aini

i-A

fr.k

ahra

man

ensi

s

Bah

ariy

a

Poo

rly

foss

ilife

rous

inte

rval

Ab

uR

oas

h?Cam-Mast

Fm.

Zone

Fig. 3 Composite chart illustrating the lithologic composition of the Qattara Rim-1X borehole, the percentage distribution of particulate organicmatter and palynofacies assemblage characteristics

Arab J Geosci

north Western Desert of Egypt was studied by many authorssuch as Parker (1982) and Younes (2002).

In this study, exine colour of smooth pteridophyte spores,i.e. Deltoidospora was investigated using the Pearson’s(1984) colour chart to determine the thermal alteration index(TAI) and the theoretical vitrinite reflectance (Ro %). Thestudied sediments from the well are characterised by ther-mally mature organic matter reflected on spore’s colours thatrange from orange to brown. These colours suggest TAIvalues of +2 to 3 and vitrinite reflectance (Ro %) values of0.5 to 0.9 according to Pearson (1984). Therefore, the lowerpart of the Qattara Rim-1X well exhibits a potential maturegas source rock corresponding to the Kharita and Bahariyaformations. A potential mature oil source rock is indicatedfrom the overlying Abu Roash Formation.

Palaeoecology

Changes in composition, relative abundance, and taxonomicdiversity of both pollen and spore grains and phytoplank-tons may be used to determine proximity of depositionalsites to source vegetation (Batten 1996). Changes in thepalynofacies composition may provide information regard-ing the interpretation of depositional environments (e.g.Wall et al. 1977; Lister and Batten 1988; Harker andSarjeant 1990; Tyson 1993, 1995; Batten 1996).

Palynomorphs from the lower part of the section (depth7,670–5,330 ft, 2,338–1,625 m) suggest that sediments of themiddle Albian and the upper Albian–middle Cenomanianwere deposited in a brackish marginal marine environment.An interpretation that is based on the occurrence of the

skolochorate Systematophora, proximate Cyclonepheliumand Circulodinium and the cavate Subtilisphaera dinoflagel-late cysts and large influx of terrestrial palynomorphs alongwith the phytoclasts-dominated palynofacies (e.g. Davey1970; Harding 1986). Dysoxic–anoxic conditions aresuggested to prevail in this marginal setting as indicated bythe position of the samples in the ternary plot of Tyson (1995).

A minor transgressive, inner shallow marine phase isfollowed (depth 4,470–3,950 ft, 1,362–1,204 m) becausethe frequencies of the open marine (middle shelf)skolochorate dinocysts such as Oligosphaeridium andFlorentinia increased (e.g. Dale 1983; Lister and Batten1988). The increase in the abundance of the dinoflagellatecysts in the upper part of the section (Fig. 5) generallyimplies deposition in a normal marine environment, as thefrequency of the dinocysts was found to show offshoreincreases (e.g. Davey 1970). The slight increase in thenumbers of the gonyaulacoid over the peridinioid cysts(Fig. 5) supports the suggested inner-shelf depositional en-vironment (Tyson 1993, and the references therein). Theabove-mentioned ternary plot suggests that sediments ofthe upper Cenomanian–Turonian and the ?Campanian–Maastrichtian were deposited in a shelfal setting havingsuboxic–anoxic conditions. High percentages of AOM inthe upper part of the section also support this slightly deepersetting. These high AOM frequencies reflect more oxygen-depleted conditions than those recorded from the previouspalynofacies, and indicate the site of deposition was locatedto some extent far from active fluvio-deltaic systems ofstrong terrestrial material influx (Tyson 1993).

The abundance of the hygrophilous palynomorphs (mainlyfern spores) such as Deltoidospora, Cicatricosisporites and

10

1

98

2

11

7

5

6

4

3

124000

5000

6000

Lat

eC

eno

man

ian

-Tu

ron

ian

7000

8000

50 %

Oth

erte

rres

tria

lpal

yno

mo

rph

s

Hyg

rop

hilo

us

(fer

nsp

ore

s)

Xer

op

hyt

esA

rau

/Inap

ert

Go

nya

ula

coid

Per

idin

ioid

50 %50 %

Per

idin

ioid

Sko

loch

ora

te

Pro

xim

ate

&P

roxi

mch

ora

te

50 %M

arin

e

No

nm

arin

e

50 %

Sp

ore

s

Gym

no

sper

ms

Ang

iosp

erm

s

Din

ofl

agel

late

sw

ith

Mic

rofo

ram

inif

eral

test

linin

gs

A B C D E

L.

Alb

ian

-M.

Cen

om

ania

nM

idd

leA

lbia

n

?Cam-Mast ?Khoman A

Mid

dle

Alb

ian

Ela

tero

spo

rite

skl

aszi

i-A

fro

po

llis

jard

inu

sE

late

r.ca

stel

aini

i-A

fr.k

ahra

man

ensi

sP

oorl

yfo

ssili

fero

usin

terv

al

Kh

arita

Bahariya

Ab

uR

oas

h

Fig. 5 Composition of palynomorph assemblages in the Qattara Rim-1X borehole. a Palynomorph categories; b Terrestrial palynomorphscategories; c Ratio of peridinioid versus gonyaulacoid; d Dinoflagellate categories; e Ratio of marine versus nonmarine palynomorphs

Arab J Geosci

Concavissimisporites in most of the studied samples probablyreflects local pteridophyte vegetation and wet lowlands(Playford 1971; Schrank and Mahmoud 1998; Atta-Petersand Salami 2006). Pteridophytes are known to thrive in wetlowlands, such as riversides and coastal areas (Pelzer et al.

1992; Abbink et al. 2004).Crybelosporites, a water fern, at thelower part of the section, suggests occurrence of freshwaterbodies, probably lakes and ponds (Schrank and Mahmoud1998; Mahmoud and Moawad 2002). Palms (e.g. Arecipitesand Longapertites) may have been abundant in tropical humid

Table 1 Summary of palynofacies, kerogen type, spore/pollen colour, TAI, Vitrinite reflectance (Ro %), thermal maturation and source rockpotential of the Qattara Rim-1X sediments

Pal

yno

faci

es

Sp

ore

colo

ur

TAI

Ro

%

Ker

og

enty

pe

Th

erm

alm

atu

rity

HC

po

ten

tial

Mat

ure

oil-

win

do

w s

tag

e

0.5

to 0

.9 %

2+ t

o 3

Ora

ng

e to

bro

wn

B (

AO

M-d

om

inat

ed)

A (

ph

yto

clas

ts-d

om

inat

ed)

II (O

il-p

ron

e m

ater

ial)

III (

Gas

-pro

ne

mat

eria

l)

Po

ten

tial

oil

sou

rce

rock

Po

ten

tial

gas

so

urc

e ro

ck

4000

5000

6000

7000

8000

10 (4190)

1 (7670)

9 (4670)

8 (4770)

2 (7380)

11 (4050)

7 (5330)

5 (6160)

6 (5660)

4 (6530)

3 (6970)

12 (3950)

....................................................................................................

..............

..............

.......................................................................................................................................................................................................................................................................................................

Sam

ple

s(d

epth

ft.)

Lit

ho

log

y

Dep

th (

ft.)

Age?Khoman A

Present work

Turo

nia

n-

San

ton

ian

Cen

om

ania

nC

eno

man

ian

Cla

stic

Alb

ian

Ala

mei

n F

orm

atio

n

Zone Fm.AM

OC

O19

92

Kh

arita

Mid

Alb

ian

Ela

tero

spo

rite

s kl

aszi

i-A

fro

po

llis

jard

inu

sE

late

r. ca

stel

aini

i-A

fr. k

ahra

man

ensi

s

Bah

ariy

a

Lat

e A

lbia

n-

Mid

Cen

om

ania

n

Poo

rly

foss

ilife

rous

inte

rval

Ab

u R

oas

h

?Cam-Mast

Lat

e C

eno

man

ian

-Tu

ron

ian

Cmp-Mast

Arab J Geosci

lowlands of the coastal plain, where they were associated withpteridophytes and other plants that inhabited lowland sites(Mahmoud and Schrank 2007). The common araucariaceanpollen frequency reflects a conifer vegetation on relativelydry hinterlands (Schrank and Mahmoud 1998; Schrank2001; Mahmoud and Moawad 2002). The occurrence ofClassopollis could also reflect derivation from conifers inupland areas far removed from the site of deposition (Yi etal. 2003). In terms of palaeoclimate, the occurrence ofClassopollis and Ephedripites pollen grains, both of whichare commonly interpreted as xerophytic elements (Schrankand Nesterova 1993; Schrank and Ibrahim 1995; Schrank andMahmoud 1998) does not imply general dry conditions be-cause they are not as abundant as ferns. The common toabundant occurrence of the angiosperm pollen Afropollis inmost of the studied section indicates more local coastal humidconditions (Schrank 2001). Therefore, a regional warm andsemi-arid palaeoclimate is suggested to prevail duringdeposition of the studied sediments but with a localhumid condition developed near or at the site of thewell. This semi-arid condition would contradict in partthe well-known warm-arid palaeoclimate in the majorityof the Albian–Cenomanian Elaterates Province and theSenonian Palm Province of Herngreen et al. (1996), whichare characterised by the dominance of Classopollis,Ephedripites and Araucariacites/Inaperturopollenites pollengrains. Our interpretation is supported by the coastalpalaeogeographic position of northern Egypt during the midand late Cretaceous times.

Conclusions

The palynological and palynofacies analyses of 12 produc-tive cuttings samples from the Cretaceous sediments of theQattara Rim-1X well led to the following conclusions(Table 1):

1. Two well-established miospore biozones, although infor-mal, and with a third poorly fossiliferous biozone weredescribed. These include from the oldest to youngest: I.Elaterosporites klaszii-Afropollis jardinus AssemblageZone (mid Albian). II. Elaterocolpites castelainii–Afropollis kahramanensis Assemblage Zone (lateAlbian–mid Cenomanian). III. Poorly fossiliferous inter-val (late Cenomanian–Turonian to ?Campanian–Maastrichtian).

2. This study enabled us to shed some light on possibleregional extended downward ranges of the two poten-tial regional important key angiosperm pollensCretacaeipori tes densimurus and Afropol l i skahramanensis into the mid Albian and the lateAlbian respectively. Further studies on range of the

two species are needed to reinforce these extendedextensions.

3. The Laramide tectonic event was detected here by thepalynostratigraphy and is thought to have affected thestudy area by the latest Turonian time and is representedby a profound break in sedimentation of the Coniacian–Santonian sediments at least.

4. The palynofacies analysis and visual assessment of theorganic thermal maturation indicates the Kharita andBahariya formations (middle Albian and upperAlbian–middle Cenomanian) as potential mature gassource rocks, and the Abu Roash Formation (upperCenomanian–Turonian) as a potential mature oil sourcerock.

5. Qualitative and semi-quantitative analyses of thepalynofacies and some selected palynomorphs ofpalaeoecological significance suggest the Kharitaand Bahariya formations were deposited in a mar-ginal marine environment under dysoxic–anoxicconditions. A slight (transgressive) inner shallowmarine setting of prevailing suboxic–anoxic conditionsis suggested as the depositional environment of the AbuRoash Formation. A regional warm and semi-arid climatebut with a local humid condition developed at the site ofthe well is suggested to prevail. The interpreted semi-aridcondition contradicts in part the well-known, warm-aridpalaeoclimate in the majority of the Albian–CenomanianElaterates Province and the Senonian Palm Province ofHerngreen et al. (1996).

Acknowledgements The first author thanks Prof. Zhiyan Zhou,Nanjing Institute of Geology and Palaeontology, Chinese Academyof Sciences, for offering research stay in China and for his support. Thepresent study is supported by the State Key Laboratory ofPalaeobiology and Stratigraphy, Chinese Academy of Sciences, Chinaunder No. 65335. We are grateful to authorities of Egyptian GeneralPetroleum Corporation for providing samples and borehole log.

Appendix

List of speciesSpores and Pollen

Afropollis jardinus (Brenner) Doyle et al., 1982Afropollis kahramanensis Ibrahim and Schrank, 1995Afropollis sp.Araucariacites australis Cookson ex Couper, 1953Arecipites punctatus Wodehouse, 1933Arecipites sp.Balmeisporites holodictyus Cookson and Dettmann, 1958Balmeisporites sp.Callialasporites dampieri (Balme) Sukh Dev, 1961Callialasporites sp.

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Cicatricosisporites orbiculatus Singh, 1964Cicatricosisporites sinuous Hunt, 1985Cicatricosisporites spp.Cingulatipollenites aegyptiaca Saad and Chazaly, 1976Classopollis torosus (Reissinger) Couper, 1958Classopollis brasiliensis Herngreen, 1975Classopollis classoides Pflug, 1953Classopollis sp.Concavisporites sp.Concavissimisporites punctatus (Delcourt andSprumont) Brenner, 1963

Cretacaeiporites densimurus Schrank and Ibrahim,1995

Crybelosporites pannuecus (Brenner) Srivastava, 1977Cycadopites sp.Deltoidospora spp.Duplexisporites generallis Déak, 1962Echitriporites trianguliformis van der Hammen andGarcia de Mutis, 1966

Elaterosporites klaszii (Jardiné and Magloire) Jardiné,1967

Elaterocolpites castelainii Jardiné and Magloire, 1965Ephedripites straight Brenner, 1968Ephedripites jansonii (Pocock) Müller, 1968Ephedripites sp.Foveotricolpites gigantoreticulatus (Jardiné andMagloire) Schrank, 1987

Inaperturopollenites spp.Laevigatosporites sp.Lakiapollis ovatus (Cenozoic pollen) Venkatachala andKar, 1969

Liliacidites sp.Longapertites sp.Pilosisporites sp.Pseudoculopollis sp.Punctatisporites spMatonisporites sp.Murospora florida (Balme) Dettmann, 1963Murospora sp.Todisporites major Couper, 1958Todisporites sp.Triplanosporites sp.Triporites sp.Tricolporopollenites sp.Scabratriporites simpliformisSpheripollenites sp.Spinizonocolpites sp.Stellatopollis sp.Retimonocolpites variplicatus Schrank and Mahmoud,1998

Rousea delicipollis Srivastava, 1975Rousea sp. cf. R. delicipollis Srivastava, 1975Rousea sp.

Verrucosisporites sp.

Dinoflagellate cysts

Cannosphaeropsis utinensisDowniesphaeridium aciculare Davey, 1969Sepispinula huguoniotii Davey, 1969Cleistosphaeridium sp.Circulodinium distinctum (Deflandre and Cookson)Jansonius, 1986

Coronifera tubulosa Cookson and Eisenack, 1974Coronifera oceanica Cookson and Eisenack, 1958Cyclonephelium vannophorum Davey, 1969Cyclonephelium sp.Dinopterygium tuberculatum (Eisenack and Cookson)Stover and Evitt, 1978

Dinopterygium cladoides Deflandre, 1935Florentinia cooksoniae (Singh) Duxbury, 1980Florentinia radiculata (Davey and Williams) Daveyand Verdier, 1973

Florentinia berran Below, 1982Florentinia mantellii (Davey and Williams) Davey andVerdier, 1973

Florentinia sp.Impagidinium sp.Odontochitina porifera Cookson, 1956Odontochitina operculata (O. Wetzel) Deflandre andCookson, 1955Oligosphaeridium complex (White) Davey andWilliams, 1966

Oligosphaeridium pulcherrimum (Deflandre andCookson) Davey and Williams, 1966Oligosphaeridium sp.Palaeoperidinium sp.Spiniferites ramosus (Ehrenberg) Mantell, 1854Spiniferites multibrevis (Davey and Williams) Below,1982

Spiniferites sp.Surculosphaeridium longifurcatum (Firtion, 1952)Davey et al., 1966

Subtilisphaera senegalensis Jain and Millepied, 1973Subtilisphaera sp.Systematophora areolata Klement, 1960,Systematophora sp.

Microforaminiferal test liningsMarine acritarchs

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