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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: [email protected]
A. S. Deaf :M. S. MahmoudFaculty of Science, Geology Department, Assiut University,Assiut 71516, Egypt
Arab J GeosciDOI 10.1007/s12517-013-0954-x
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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1
98
2
11
7
5
6
4
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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