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Tertiary dinoflagellate cysts from the Mit Ghamr-1 well, Nile Delta, Egypt
Review Of Palaeobotany and Palynology, 63 (1990): 259 267 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
259
Tertiary dinoflagellate cysts from the Mit Ghamr-1 well, Nile Delta, Egypt S a l a h Y. E1-Beialy Department of Geology, Faculty of Science, El-Mansoura University (Egypt) (Received October 24, 1989; revised and accepted February 5, 1990)
ABSTRACT El-Beialy, S.Y., 1990. Tertiary dinoflagellate cysts from the Mit Ghamr-l well, Nile Delta, Egypt. Rev. Palaeobot. Palynol., 63: 259- 267. Nine conventional core samples from the Mit Ghamr-l well, situated on the eastern side of the Damietta branch of the River Nile. Egypt, have been investigated for palynomorph recovery. Dinocyst biostratigraphy has indicated an importance in dating the studied sequence. Results have confirmed the presence of Middle, Late, Eocene, Oligocene Miocene, Late Miocene and Early Pliocene to Quaternary sediments. Comparable assemblageshave been reported from other Egyptian Tertiary sediments, mainly from elsewhere in the Nile Delta, the Western Desert and Sinai.
Introduction This study deals with the palynostratigraphic analysis of the E o c e n e - Q u a t e r n a r y sequence which was penetrated by the Mit Ghamr-1 well, situated on the eastern side of the Damietta branch of the River Nile. The well, which is located at 30°41'44"N, 31°16'26"E, was drilled by the International Egyptian Oil C o m p a n y (IEOC) in 1982 (Fig. 1). Although relatively few palynological studies have been carried out on the T e r t i a r y - Q u a t e r n a r y sequence of the Nile Delta, they have proved stratigraphically and palaeoenvironmentally useful. Poumot and Bouroullec (1984) studied spores and pollen grains recovered from nine wells offshore the western part of the Nile Delta and of Miocene-Pliocene age. This was followed by the work of Saad et al. (1987) who examined samples from the Abu Qir-2X well, from the western part of the Nile Delta. They dated it as being Plio-Pleistocene and presented palaeoenvironmental interpretations. EI-Beialy (1988a) gave an account on the
palynostratigraphy of the Oligocene to Pliocene succession in the Kafr E1 Dawar-1 well, from the West Nile Delta, based mainly on the stratigraphic distribution of dinocysts. El-Beialy (1988b) set up an informal Neogene zonation based on dinocyst assemblages from the Qawasim-1 well from the northern Nile Delta. Lately E1-Beialy (1988c) reported a single dinocyst assemblage of Late Eocene age in the North Dilingat-IX well, from the western part of the Nile Delta. The purpose of the present study is to date the Tertiary sequence in the Mit G h a m r - I well, with an emphasis on the dinoflagellate cysts. It is also intended to correlate the M i t - G h a m r - I succession with other adjacent wells.
Stratigraphy The Mit Ghamr-1 well was drilled to a depth of 2201 m below sea level and penetrated deposits of Mesozoic-Cenozoic age. According to IEOC (1982), the Mit G h a m r - I succession (Fig.2) is differentiated into the following stratigraphic units from b o t t o m to top:
260
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Fig.l. Map showing the location of the Mit Ghamr-I well, Nile Delta, Egypt.
(l) Chalk Formation (2) Mokattam Formation (3) Un-named Formation (4) Abu Zaabal Formation (5) Sidi Salem Formation (6) Abu Madi Formation (7) Kafr E1 Sheikh Formation (8) E1 Wastani Formation (9) Mit Ghamr Formation The Chalk Formation at the base attains a thickness of 200 m, ranging from 2201-2000 m. It is composed of white, medium hard chalky limestone, occasionally cherty in the lower part. Its age is Campanian-Maastrichtian (Shahin, 1981) based on the presence of the planktonic foraminiferal species Globotruncana elevata (Brotzen), G. tricarinata (Quereau) and Gansserina gansseri (Bolli). The Mokattam Formation consists of nummulitic, argillaceous limestone interbedded with marls. It unconformably overlies the Chalk Formation and is assigned a Middle Eocene age (Viotti, 1968). The Un-named Formation is composed of a very thick series of argillaceous, carbonaceous shales with some interbeddings of glauconitic, sandy limestone. It could be referred to the Dabaa Formation in the present work, which has been correlated to sediments of Oligocene age.
The Abu Zaabal Formation unconformably overlies the Un-named Formation. In Oligocene time, basalt dolerite dykes and flows took place as a result of tensional movements in the rift zone. The Sidi Salem Formation is composed of clayey shale with few sandy interbeds. The age of the Sidi Salem Formation, ranges from Early Oligocene (Zaghloul et al., 1979; E1-Beialy, 1988a) to Middle Miocene (Rizzini et al., 1978; E1-Beialy, 1988b). The Abu Madi Formation is represented by a series of thick bodies of sands, in part pebbly, with interbedded thin shales. The age of the formation in the western part of the Nile Delta is Early Miocene based on foraminiferal and palynological evidence (Zaghloul et al., 1979; El-Beialy, 1988a). In the central part of the Delta, Rizzini et al. (1978) assumed an Early Pliocene age, based on the presence of the foraminiferal Sphaeroidinellopsis Zone. The Abu Madi Formation is the gasproducing horizon of the Nile Delta gas fields. It is not considered here due to lack of samples. The Kafr El Sheikh Formation consists of soft clays with interbedded sands. It ranges in age from Early to Middle Pliocene (Rizzini et al., 1978). However, Zaghloul et al. (1979) dated it as Early Miocene to Middle Pliocene age, based on foraminiferal evidence in the western part of the Nile Delta.
TERTIARY
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262 The E1 Wastani Formation consists of thick quartzose sands with argillaceous interbeds. Its upper limit is ill-defined and its age is Late Pliocene (IEOC, 1982). The overlying Mit Ghamr Formation is not considered in this report due to unavailability of samples. Its age is uppermost Pliocene to Quaternary, based on foraminifera (Zaghloul et al., 1979).
Material and Techniques Nine conventional core chip samples from the sequence penetrated by the Mit Ghamr-l well were made available. The lithology of the examined samples together with the common rock units (formations) encountered in the present work are shown in Fig.2. Five grams of material were processed to ensure adequate palynomorph recovery. The samples were digested with HCI to remove carbonates followed by 50% HF for approximately 72 hours to remove silicates. They were then treated successively with concentrated HC1, HNO3 and NaOH. The organic residues were concentrated by sieving and the organic fraction between l0 and 125 ~tm for each sample was Safranin-stained and prepared as permanent scatter mounts. Few drops of Polyvinyl alchohol (PVA) were added to the residue for dispersion and Canada Balsam was the mounting medium. Counts of 200 specimens per sample were made from each sample. Biostratigraphically significant dinocyst species, spores and pollen are illustrated in Plate 1. The slides containing the figured specimens, located by England Finder references are held in the collections of the Department of Geology, Faculty of Science, E1-Mansoura University, Egypt.
Palynological results Samples yielded diverse and well preserved dinocyst assemblages. In addition, a low diversity of spores and pollen was recorded from samples 4, 2 and 1 (Fig.2). A dinocyst zonation is not proposed here because too few samples were studied and too few first appearances of taxa were observed. The distribution of selected taxa is shown in Fig.2. The
S.Y,EL-BEIALY most important taxa in each sample are discussed below, following the dinocyst nomenclature of Lentin and Williams (1989).
Samples 9 and 8 (depth 2200 m and 208l m) Rare, poorly preserved specimens of Spiniferites and Achomosphaera were recovered from both samples. The lack of diagnostic palynomorphs precludes dating either sample. Based on planktonic foraminiferal evidence, Shahin (1981) dated these two samples within the Chalk Formation as being Campanian to Maastrichtian supporting the age given by the IEOC (1982) on the basis of lithological correlation.
Sample 7 (depth 1987m) The rich, varied dinocyst assemblage in this sample contains Riculacysta perforata Stover, Areosphaeridium pectiniJorme (Gerlach) Stover et Evitt emend. Sarjeant, Adnatosphaeridium reticulense (Pastiels) De Coninck, Apectodinium homomorphum (Deflandre et Cookson) Lentin et Williams emend. Harland and Glaphyroeysta intricata (Eaton) Stover et Evitt. Other taxa recorded include Homotryblium tenuispinosum Davey et Williams, Cordosphaeridium sp. and Hystrichokolpoma rigaudiae Deflandre et Cookson. Spores and pollen are absent. Adnatosphaeridium reticulense has been recorded from the Early Eocene of Belgium (Pastiels, 1948: De Coninck, 1969), Germany (Gocht, 1969) and Australia (Deflandre and Cookson, 1955). This species ranges into the Middle Eocene of France (Gruas-Cavagnetto, 1971). Glaphyrocysta intricata is restricted to the Middle Eocene of northwest Europe (Eaton, 1971, 1976; Williams and Bujak, 1977; Costa and Downie, 1979). The assemblage recorded from this sample is partly similar to the one recognised from the Adnatosphaeridium reticulense Peak Zone of Williams and Bujak (1977) defined from the Cenozoic of offshore eastern Canada, of Middle Eocene age. The age of the sample discussed above was considered to be Middle Eocene (IEOC, 1982) based on lithological data. The age as defined from
263
TERTIARY DINOFLAGELLATE CYSTS
dinocyst evidence (the present report), is considered to be Middle Eocene as well.
Sample 6 (depth 1975 m) The occurrence of Thalassiphora pelagica (Eisenack) Eisenack et Gocht emend. Benedek et Gocht and Homotryblium tasmaniense Cookson et Eisenack is characteristic of this sample. Less abundant or auxiliary taxa associated with the characteristic forms include Apectodinium homomorphum, Adna-
tosphaeridium reticulense, Wetzeliella lunaris Gocht, Glaphyrocysta intricata and Charlesdowneia reticulata (Williams et Downie) Lentin et Vozzhennikova 1.
Wetzeliella lunaris was observed by Gocht (1969) from the Early Eocene of Germany. The range of this species was extended by Eaton (1976) and Bujak et al. (1980) into the early Middle Eocene succession of southern England. Charlesdowneia reticulata occurs in the Early Eocene of the London Basin in southern England (Williams and Downie, 1966; Eaton, 1976; Islam, 1983). The youngest occurrence of this species is in the Upper Eocene succession of offshore eastern Canada (Williams and Bujak, 1977). Homotryblium tasmaniense was originally reported from the Palaeocene sediments of Tasmania (Cookson and Eisenack, 1967). It was subsequently recorded from deposits as young as the Middle Eocene of Nigeria (Oloto, 1984). The age of this sample was given as Middle Eocene (IEOC, 1982). The dinocysts evidence (this paper) also determined it to be early Middle Eocene. Sample 5 (depth 1903 m) The age of this sample is determined by the presence of Diphyes colligerum (Deflandre et Cookson) Cookson, Glaphyrocysta intricata, Charlesdowneia coleothrypta (Williams et Downie) Lentin et Vozzhennikova 1, Homotryblium floripes (Deflandre et Cookson) Stover, Homotryblium tenuispinosum and Dapsilidinium pastielsii (Davey et Williams) Bujak et al. The first-mentioned 1Recentlyamended.
species is restricted to Late Eocene sediments worldwide (Williams, 1975; Williams and Brideaux, 1975; Bujak, 1976; Barss et al., 1979: Chfiteauneuf, 1979; Herngreen, 1983; Wilson, 1984). The highest occurrence of Diphyes colligerum from Egypt was also reported in Late Eocene sediments of the Western Desert and the Nile Delta (El-Bassiouni et al., 1988; El-Beialy, 1988c; E1-Beialy and Shahin, 1990). So the Late Eocene age seems justified on the basis of the highest occurrence of Diphyes colligerum observed within the Late Eocene D. colligerum Assemblage Zone of Williams (1975) and Williams and Bujak (1977) recorded from offshore eastern Canada. From the discussion given above, it is considered that the age of sample 5 is Late Eocene, thus supporting the findings of the IEOC (1982).
Sample 4 (depth 1633 m) Palynomorphs are too scarce to make an age determination. However, the presence of the very characteristic pollen Echiperiporites estelae Germeraad et al. suggests an Oligocene-Miocene age, based on its occurrence in the basal part of Zone S of Oloto (1984) in Nigerian sediments. "Ephedripites sp. and Cicatricosisporites sp. also were recovered from sample 4. The only dinocyst found was Operculodinium sp.
Sample 3 (depth 1000 m) This sample contains a rich dinocyst assemblage dominated by Invertocysta tabulata Edwards, Achomosphaera andalousiensis Jan Du Chine emend. Jan Du Chine et Londeix, Reticulatosphaera actinocoronata (Benedek) Bujak et Matsuoka and a single specimen of Nematosphaeropsis lativittatus Wrenn. Long-ranging species such as Lingulodinium machaerophorum (Deflandre et Cookson) Wall, Impagidinium patulum (Wall) Stover et Evitt, I. paradoxum (Wall) Stover et Evitt, Spiniferites ramosus (Ehrenberg) Loeblich et Loeblich, Achomosphaera ramulifera (Deflandre) Evitt, Operculodinium centrocarpum (Deflandre et Cookson) Wall, Nematosphaeropsis labyrinthea (Ostenfeld) Reid and Dapsilidinium pastielsii were also recorded. Among the pollen grains Pinus is the predominant
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"1ERTIARY DINOFLAGELLATkCYSTS
component. Periporate pollen belonging to the Chenopodiaceae also were recorded in very low frequencies. The youngest stratigraphic occurrence of Invertoo'sta tabulata lies within Late Miocene sediments of the Rockall Plateau (Costa and Downie, 1979 as Forma A; Edwards, 1984) and in the Piedmont Tertiary Basin of Italy (Powell, 1986). A chomosphaera andalousiensis first occurs within Late Miocene deposits (Williams, 1975; Jan Du Chine, 1977; Harland, 1978; Piasecki, 1980; Benedek, 1980) and Middle/Late Miocene boundary (Brown and Downie, 1985; Jan Du Chine and Londeix, 1988; El-Beialy and Gheith, 1990). The presence of Achomosphaera andalousiensis in sample 3 of the Mit Ghamr-I well is considered here to define the base of Late Miocene. Reticulatosphaera actinocoronata is a worldwide marker for the Late Miocene age in Canada, Rockall Plateau, Denmark, Italy, the Netherlands and Egypt (Williams, 1975; Williams and Brideaux, 1975; Williams and Bujak, 1977; Barss et al., 1979; Costa and Downie, 1979; Piasecki, 1980; Powell, 1986; Herngreen, 1987; E1-Beialy, 1988a; El-Beialy and Gheith, 1990). Its presence indicates a Late Miocene age for sample 3.
265
The age previously assigned to sample 3 was Pliocene (IEOC, 1982) based on lithological evidence. My Late Miocene age determination is supported by the results of Zaghloul et al. (1979) who reported the presence of the Globorotalia ascostaensis and G. menardii foraminiferal Zones in the basal part of the Kafr E1 Sheikh Member II in the Kafr E1 Dawar-1 well, Nile Delta. All were assigned a Late Miocene age. Samples 2 and 1 (depth 749 m and 507 m)
Dinocysts are rare in both samples. Pteridophytic spores, Gramineae and Chenopodiaceae pollen are abundant. The only dinocyst represented is Tuberculodinium vancampoae (Rossignol) Wall. The latter species is not a useful index ranging from Late Oligocene to Pleistocene (Williams and Bujak, 1985). Comparison of this assemblage with that of Saad et al. (1987) from the Abu Qir-2X well, Nile Delta, of Plio-Pleistocene age, gives a similar age dating. In the absence of any evidence for a Pliocene age as given by the IEOC (1982), an age range for samples l and 2 from Pliocene to Quaternary is postulated.
PLATE 1 (All figures are approximately x 500, unless otherwise noted, the location of each figured specimen is given using the England Finder
references). I. 2. 3. 4. 5. 6, 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.
Achomosphaera andalousiensis Jan Du Ch6ne emend. Jan Du Ch6ne et Londeix, 1988, sample 3, Q29. Adnatosphaeridium reticulense (Pastiels) De Coninck, 1969, sample 7, Q40. Apectodinium homomorphum (Deflandre et Cookson) Lentin et Williams emend. Harland, 1979, sample 7, 037. Glaphyrocysta intricata (Eaton) Stover et Evitt, 1978, sample 6, E39. Diphyes colligerum (Deflandre et Cookson) Cookson 1965. sample 5, M45. Homotryblium tasmaniense Cookson et Eisenack 1967, sample 6, M24, W37. Stelladinium sp., sample 7, M35. lnvertoeysta tabulata Edwards, 1984, sample 3, P36. Charlesdowneia reticulata (Williams et Downie) Lentin et Vozzhennikova 1989, sample 6, V47. lmpagidinium patulum (Wall) Stover et Evin, 1978, sample 3, E27. Thalassiphora pelagica (Eisenack) Eisenack et Gocht emend. Benedek et Gocht, 1981, sample 6, L41. Nematosphaeropsis lativittalus Wrenn, 1988, sample 3, Q27. Echiperiporites estelae Germeraad et al., 1968, sample 4, $41. Chenopodiaceae pollen, sample 3, T38, x 750. Gramineae pollen, sample 1, x 57, x 750. Tuberculodinium vancampoae (Rossignol) Wall 1967, sample 2, J15. Reticulatosphaera actinocoronata (Benedek) Bujak et Matsuoka, 1986, sample 3, L30. Polypodiaceae (trilete spore), sample 1, D52. Riculacysta perforata Stover, 1977, sample 7, J39. Wetzeliella lunaris Gocht, 1969, sample 6, J29.
266
Conclusions Five distinctive dinocyst and pollen assemblages are d e f i n e d f r o m the M o k a t t a m , U n - n a m e d , Sidi Salem, K a f r E1 S h e i k h a n d the E1 W a s t a n i F o r m a t i o n s o f the M i t G h a m r - 1 well, Nile D e l t a , E g y p t . N o d i a g n o s t i c p a l y n o m o r p h a s s e m b l a g e is r e c o g n i s e d f r o m the Basal C h a l k F o r m a t i o n , t h u s p r e c l u d i n g its d a t i n g . I n t e r p r e t a t i o n s o f these a s e m b l a g e s yielded significant age d e t e r m i n a t i o n s as follows: (1) T h e M o k a t t a m F o r m a t i o n is o f M i d d l e a n d Late E o c e n e age as i n d i c a t e d by the I E O C (1982). (2) T h e s a m p l e f r o m w i t h i n the U n - n a m e d F o r m a t i o n is a s s i g n e d a n O l i g o c e n e - M i o c e n e age a n d n o t O l i g o c e n e as r e p o r t e d b y the I E O C (1982). (3) T h e b a s a l p a r t o f the K a f r E1 S h e i k h F o r m a t i o n is o f Late M i o c e n e age a n d n o t P l i o c e n e as g i v e n by the I E O C (1982). T h e o v e r l y i n g s a m p l e s f r o m the K a f r El S h e i k h a n d E1 W a s t a n i F o r m a t i o n s are o f P l i o c e n e - P l e i s t o c e n e age.
Acknowledgements T h e a u t h o r t h a n k s D r . J. W r e n n , A m o c o P r o d u c t i o n C o m p a n y , T u l s a , O K . , U . S . A . for s t i m u l a t i n g c o m m e n t s a n d critically r e a d i n g the m a n u s c r i p t . I a m also g r a t e f u l to the m a n a g e m e n t o f the I E O C for p r o v i d i n g the m a t e r i a l a n d well log n e c e s s a r y for this study.
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TERTIARY DINOFLAGELLATE CYSTS
Harland, R., 1978. Quaternary and Neogene dinoflagellate cysts. In: B. Thusu (Editor), Distribution of biostratigraphically diagnostic dinoflagellate cysts and microspores from the northwest European continental shelf and adjacent areas. Inst. Kontinentals6kkelundersokelser Publ., 100:7 17. Herngreen, G.E.W., 1983. Dating Tertiary strata in seven boreholes in the Oldenzaal-Denekamp area (Twente) eastern Netherlands. Meded. Rijks Geol. Dienst, 37 (3): 125 153. Herngreen, G.F.W., 1987. Correlation between Miocene beds of the SE Netherlands and Italy based on dinoflagellate biozonation. Meded. Werkgr. Tert. Kwart. Geol., 24 (I-2): 31 40. IEOC 1982. Nile Delta, Geology and hydrocarbon evaluation, summary log. Islam, M.A., 1983. Dinoflagellate cysts from the Eocene of the London and the Hampshire Basins, southern England. Palynology, 7: 71-92. Jan Du Chine, R., 1977. l~tude palynologique du Mioc6ne supdrieur Andalou (Espagne). Rev. Esp. Micropaleontol, 9: 97 114. Jan Du Ch6ne, R. and Londeix, L., 1988. Donndes nouvelles sur Achomosphaera andalousiense Jan Du Ch~ne, 1977, kyste de dinoflagelle fossile. New information about Achomosphaera andalousiense Jan Du Chine, 1977, fossil dinoflagellate cyst. Bull. Centr. Rech. Explor. Prod. Elf-Aquit., 12 (1): 237-250. Lentin, J.K. and Williams, G.L., 1989. Fossil dinoftagellates: Index to genera and species. AASP Contr. Ser, 20, 473 pp. Oloto, I.N., 1984. A palynological study of the Late Cretaceous and Tertiary boreholes from southern Nigerian sedimentary basin. Thesis, Univ. Sheffield, Unpubl. Pastiels, A., 1948. Contribution ~i l'6tude des microfossiles de l'Eocene belge. M6m. Mus. R. Hist. Nat. Belg., 109: 1-77. Piasecki, S., 1980. Dinoflagellate cyst stratigraphy of the Miocene Hodde and Gram Formations, Denmark. Bull. Geol. Surv. Denmark, 29:53 76. Poumot, C. and Bouroullec, J., I984. Palynoplanktological contribution to the Mio-Pliocene environmental and paleoclimatological conditions of the Nile Delta area. Egyptian General Petrol. Corpor., 7th Explor. seminar, Cairo, pp.325-334. Powell, A.J., 1986. The stratigraphical distribution of Late
Miocene dinoflagellate cysts from the Castellanian superstage stratotype, northwest Italy. AASP Contr. Set., 17:129 149. Rizzini, A., Vezzani, F., Cococcetta, A. and Milad, G., 1978. Stratigraphy and sedimentation of a Neogene Quaternary section in the Nile Delta area. Mar. Geol., 27:327 348. Saad, S.I., Zaghloul, Z.M. and EI-Beialy, S.Y., 1987. Late Tertiary-Quaternary palynomorphs from the northern coast of the Nile Delta, Egypt. N. Jahrb. Geol. PaF,iontol. Monatsh., 5: 314-320. Shahin, A.M.M., 1981. Biostratigraphic studies on some subsurface Upper Cretaceous sediments from the Nile Delta. Thesis, Mansoura Univ., 161 pp. (Unpubl.). Viotti, C., 1968. Part 1II: Eocene planktonic foraminiferal zonation. In: Viotti, C. and Mansour, A. (Tertiary planktonic foraminiferal zonation from the Nile Delta, Egypt. U.A.R.). Proc. 3rd Afr. Micropaleontol. Colloq., Cairo, pp.448 459. Williams, G.L., 1975. Dinoflagellate and spore stratigraphy of the Mesozoic-Cenozoic, offshore eastern Canada. Geol. Surv. Can. Pap., 74 30 (2): 107~-161. Williams, G.L. and Brideaux, W.W., 1975. Palynologic analyses of upper Mesozoic and Cenozoic rocks of the Grand Banks, Atlantic continental margin. Geol. Surv. Can. Bull., 236: 1--63.
Williams, G.L. and Bujak, J.P., 1977. Cenozoic palynostratigraphy of offshore eastern Canada. AASP Contr. Ser. 5A: 14 47. Williams, G.L. and Bujak, J.P., 1985. Mesozoic and Cenozoic dinoflagellates. In: H.M. Bolli, J.B. Saunders and K. PerchNielsen (Editors). Plankton Stratigraphy. Cambridge Univ. Press, pp.847-964. Williams, G.L. and Downie, C., 1966. Wetzeliella from the London Clay: In: R.J. Davey, C. Downie, W.A.S. Sarjeant and G.L. Williams, Studies on Mesozoic and Cainozoic dinoflagellate cysts. Bull. Br. Mus. (Nat. Hist.) Geol. Suppl., 3:82 198. Wilson, G.J., 1984. New Zealand Late Jurassic to Eocene dinoflagellate biostratigraphy. A summary. Newsl. Stratigr., 13 (2): 104 117. Zaghloul, Z.M., Andrawis, S.F. and Ayyad, S.N., 1979. New contribution to the stratigraphy of the Tertiary sediments of Kafr E1 Dawar well No. 1, northwest Nile Delta, Egypt. Ann. Geol. Surv. Egypt, 9: 292-307.
259
Tertiary dinoflagellate cysts from the Mit Ghamr-1 well, Nile Delta, Egypt S a l a h Y. E1-Beialy Department of Geology, Faculty of Science, El-Mansoura University (Egypt) (Received October 24, 1989; revised and accepted February 5, 1990)
ABSTRACT El-Beialy, S.Y., 1990. Tertiary dinoflagellate cysts from the Mit Ghamr-l well, Nile Delta, Egypt. Rev. Palaeobot. Palynol., 63: 259- 267. Nine conventional core samples from the Mit Ghamr-l well, situated on the eastern side of the Damietta branch of the River Nile. Egypt, have been investigated for palynomorph recovery. Dinocyst biostratigraphy has indicated an importance in dating the studied sequence. Results have confirmed the presence of Middle, Late, Eocene, Oligocene Miocene, Late Miocene and Early Pliocene to Quaternary sediments. Comparable assemblageshave been reported from other Egyptian Tertiary sediments, mainly from elsewhere in the Nile Delta, the Western Desert and Sinai.
Introduction This study deals with the palynostratigraphic analysis of the E o c e n e - Q u a t e r n a r y sequence which was penetrated by the Mit Ghamr-1 well, situated on the eastern side of the Damietta branch of the River Nile. The well, which is located at 30°41'44"N, 31°16'26"E, was drilled by the International Egyptian Oil C o m p a n y (IEOC) in 1982 (Fig. 1). Although relatively few palynological studies have been carried out on the T e r t i a r y - Q u a t e r n a r y sequence of the Nile Delta, they have proved stratigraphically and palaeoenvironmentally useful. Poumot and Bouroullec (1984) studied spores and pollen grains recovered from nine wells offshore the western part of the Nile Delta and of Miocene-Pliocene age. This was followed by the work of Saad et al. (1987) who examined samples from the Abu Qir-2X well, from the western part of the Nile Delta. They dated it as being Plio-Pleistocene and presented palaeoenvironmental interpretations. EI-Beialy (1988a) gave an account on the
palynostratigraphy of the Oligocene to Pliocene succession in the Kafr E1 Dawar-1 well, from the West Nile Delta, based mainly on the stratigraphic distribution of dinocysts. El-Beialy (1988b) set up an informal Neogene zonation based on dinocyst assemblages from the Qawasim-1 well from the northern Nile Delta. Lately E1-Beialy (1988c) reported a single dinocyst assemblage of Late Eocene age in the North Dilingat-IX well, from the western part of the Nile Delta. The purpose of the present study is to date the Tertiary sequence in the Mit G h a m r - I well, with an emphasis on the dinoflagellate cysts. It is also intended to correlate the M i t - G h a m r - I succession with other adjacent wells.
Stratigraphy The Mit Ghamr-1 well was drilled to a depth of 2201 m below sea level and penetrated deposits of Mesozoic-Cenozoic age. According to IEOC (1982), the Mit G h a m r - I succession (Fig.2) is differentiated into the following stratigraphic units from b o t t o m to top:
260
s.Y EL-BEIALY
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Fig.l. Map showing the location of the Mit Ghamr-I well, Nile Delta, Egypt.
(l) Chalk Formation (2) Mokattam Formation (3) Un-named Formation (4) Abu Zaabal Formation (5) Sidi Salem Formation (6) Abu Madi Formation (7) Kafr E1 Sheikh Formation (8) E1 Wastani Formation (9) Mit Ghamr Formation The Chalk Formation at the base attains a thickness of 200 m, ranging from 2201-2000 m. It is composed of white, medium hard chalky limestone, occasionally cherty in the lower part. Its age is Campanian-Maastrichtian (Shahin, 1981) based on the presence of the planktonic foraminiferal species Globotruncana elevata (Brotzen), G. tricarinata (Quereau) and Gansserina gansseri (Bolli). The Mokattam Formation consists of nummulitic, argillaceous limestone interbedded with marls. It unconformably overlies the Chalk Formation and is assigned a Middle Eocene age (Viotti, 1968). The Un-named Formation is composed of a very thick series of argillaceous, carbonaceous shales with some interbeddings of glauconitic, sandy limestone. It could be referred to the Dabaa Formation in the present work, which has been correlated to sediments of Oligocene age.
The Abu Zaabal Formation unconformably overlies the Un-named Formation. In Oligocene time, basalt dolerite dykes and flows took place as a result of tensional movements in the rift zone. The Sidi Salem Formation is composed of clayey shale with few sandy interbeds. The age of the Sidi Salem Formation, ranges from Early Oligocene (Zaghloul et al., 1979; E1-Beialy, 1988a) to Middle Miocene (Rizzini et al., 1978; E1-Beialy, 1988b). The Abu Madi Formation is represented by a series of thick bodies of sands, in part pebbly, with interbedded thin shales. The age of the formation in the western part of the Nile Delta is Early Miocene based on foraminiferal and palynological evidence (Zaghloul et al., 1979; El-Beialy, 1988a). In the central part of the Delta, Rizzini et al. (1978) assumed an Early Pliocene age, based on the presence of the foraminiferal Sphaeroidinellopsis Zone. The Abu Madi Formation is the gasproducing horizon of the Nile Delta gas fields. It is not considered here due to lack of samples. The Kafr El Sheikh Formation consists of soft clays with interbedded sands. It ranges in age from Early to Middle Pliocene (Rizzini et al., 1978). However, Zaghloul et al. (1979) dated it as Early Miocene to Middle Pliocene age, based on foraminiferal evidence in the western part of the Nile Delta.
TERTIARY
DINOFLAGELLA'rE
261
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262 The E1 Wastani Formation consists of thick quartzose sands with argillaceous interbeds. Its upper limit is ill-defined and its age is Late Pliocene (IEOC, 1982). The overlying Mit Ghamr Formation is not considered in this report due to unavailability of samples. Its age is uppermost Pliocene to Quaternary, based on foraminifera (Zaghloul et al., 1979).
Material and Techniques Nine conventional core chip samples from the sequence penetrated by the Mit Ghamr-l well were made available. The lithology of the examined samples together with the common rock units (formations) encountered in the present work are shown in Fig.2. Five grams of material were processed to ensure adequate palynomorph recovery. The samples were digested with HCI to remove carbonates followed by 50% HF for approximately 72 hours to remove silicates. They were then treated successively with concentrated HC1, HNO3 and NaOH. The organic residues were concentrated by sieving and the organic fraction between l0 and 125 ~tm for each sample was Safranin-stained and prepared as permanent scatter mounts. Few drops of Polyvinyl alchohol (PVA) were added to the residue for dispersion and Canada Balsam was the mounting medium. Counts of 200 specimens per sample were made from each sample. Biostratigraphically significant dinocyst species, spores and pollen are illustrated in Plate 1. The slides containing the figured specimens, located by England Finder references are held in the collections of the Department of Geology, Faculty of Science, E1-Mansoura University, Egypt.
Palynological results Samples yielded diverse and well preserved dinocyst assemblages. In addition, a low diversity of spores and pollen was recorded from samples 4, 2 and 1 (Fig.2). A dinocyst zonation is not proposed here because too few samples were studied and too few first appearances of taxa were observed. The distribution of selected taxa is shown in Fig.2. The
S.Y,EL-BEIALY most important taxa in each sample are discussed below, following the dinocyst nomenclature of Lentin and Williams (1989).
Samples 9 and 8 (depth 2200 m and 208l m) Rare, poorly preserved specimens of Spiniferites and Achomosphaera were recovered from both samples. The lack of diagnostic palynomorphs precludes dating either sample. Based on planktonic foraminiferal evidence, Shahin (1981) dated these two samples within the Chalk Formation as being Campanian to Maastrichtian supporting the age given by the IEOC (1982) on the basis of lithological correlation.
Sample 7 (depth 1987m) The rich, varied dinocyst assemblage in this sample contains Riculacysta perforata Stover, Areosphaeridium pectiniJorme (Gerlach) Stover et Evitt emend. Sarjeant, Adnatosphaeridium reticulense (Pastiels) De Coninck, Apectodinium homomorphum (Deflandre et Cookson) Lentin et Williams emend. Harland and Glaphyroeysta intricata (Eaton) Stover et Evitt. Other taxa recorded include Homotryblium tenuispinosum Davey et Williams, Cordosphaeridium sp. and Hystrichokolpoma rigaudiae Deflandre et Cookson. Spores and pollen are absent. Adnatosphaeridium reticulense has been recorded from the Early Eocene of Belgium (Pastiels, 1948: De Coninck, 1969), Germany (Gocht, 1969) and Australia (Deflandre and Cookson, 1955). This species ranges into the Middle Eocene of France (Gruas-Cavagnetto, 1971). Glaphyrocysta intricata is restricted to the Middle Eocene of northwest Europe (Eaton, 1971, 1976; Williams and Bujak, 1977; Costa and Downie, 1979). The assemblage recorded from this sample is partly similar to the one recognised from the Adnatosphaeridium reticulense Peak Zone of Williams and Bujak (1977) defined from the Cenozoic of offshore eastern Canada, of Middle Eocene age. The age of the sample discussed above was considered to be Middle Eocene (IEOC, 1982) based on lithological data. The age as defined from
263
TERTIARY DINOFLAGELLATE CYSTS
dinocyst evidence (the present report), is considered to be Middle Eocene as well.
Sample 6 (depth 1975 m) The occurrence of Thalassiphora pelagica (Eisenack) Eisenack et Gocht emend. Benedek et Gocht and Homotryblium tasmaniense Cookson et Eisenack is characteristic of this sample. Less abundant or auxiliary taxa associated with the characteristic forms include Apectodinium homomorphum, Adna-
tosphaeridium reticulense, Wetzeliella lunaris Gocht, Glaphyrocysta intricata and Charlesdowneia reticulata (Williams et Downie) Lentin et Vozzhennikova 1.
Wetzeliella lunaris was observed by Gocht (1969) from the Early Eocene of Germany. The range of this species was extended by Eaton (1976) and Bujak et al. (1980) into the early Middle Eocene succession of southern England. Charlesdowneia reticulata occurs in the Early Eocene of the London Basin in southern England (Williams and Downie, 1966; Eaton, 1976; Islam, 1983). The youngest occurrence of this species is in the Upper Eocene succession of offshore eastern Canada (Williams and Bujak, 1977). Homotryblium tasmaniense was originally reported from the Palaeocene sediments of Tasmania (Cookson and Eisenack, 1967). It was subsequently recorded from deposits as young as the Middle Eocene of Nigeria (Oloto, 1984). The age of this sample was given as Middle Eocene (IEOC, 1982). The dinocysts evidence (this paper) also determined it to be early Middle Eocene. Sample 5 (depth 1903 m) The age of this sample is determined by the presence of Diphyes colligerum (Deflandre et Cookson) Cookson, Glaphyrocysta intricata, Charlesdowneia coleothrypta (Williams et Downie) Lentin et Vozzhennikova 1, Homotryblium floripes (Deflandre et Cookson) Stover, Homotryblium tenuispinosum and Dapsilidinium pastielsii (Davey et Williams) Bujak et al. The first-mentioned 1Recentlyamended.
species is restricted to Late Eocene sediments worldwide (Williams, 1975; Williams and Brideaux, 1975; Bujak, 1976; Barss et al., 1979: Chfiteauneuf, 1979; Herngreen, 1983; Wilson, 1984). The highest occurrence of Diphyes colligerum from Egypt was also reported in Late Eocene sediments of the Western Desert and the Nile Delta (El-Bassiouni et al., 1988; El-Beialy, 1988c; E1-Beialy and Shahin, 1990). So the Late Eocene age seems justified on the basis of the highest occurrence of Diphyes colligerum observed within the Late Eocene D. colligerum Assemblage Zone of Williams (1975) and Williams and Bujak (1977) recorded from offshore eastern Canada. From the discussion given above, it is considered that the age of sample 5 is Late Eocene, thus supporting the findings of the IEOC (1982).
Sample 4 (depth 1633 m) Palynomorphs are too scarce to make an age determination. However, the presence of the very characteristic pollen Echiperiporites estelae Germeraad et al. suggests an Oligocene-Miocene age, based on its occurrence in the basal part of Zone S of Oloto (1984) in Nigerian sediments. "Ephedripites sp. and Cicatricosisporites sp. also were recovered from sample 4. The only dinocyst found was Operculodinium sp.
Sample 3 (depth 1000 m) This sample contains a rich dinocyst assemblage dominated by Invertocysta tabulata Edwards, Achomosphaera andalousiensis Jan Du Chine emend. Jan Du Chine et Londeix, Reticulatosphaera actinocoronata (Benedek) Bujak et Matsuoka and a single specimen of Nematosphaeropsis lativittatus Wrenn. Long-ranging species such as Lingulodinium machaerophorum (Deflandre et Cookson) Wall, Impagidinium patulum (Wall) Stover et Evitt, I. paradoxum (Wall) Stover et Evitt, Spiniferites ramosus (Ehrenberg) Loeblich et Loeblich, Achomosphaera ramulifera (Deflandre) Evitt, Operculodinium centrocarpum (Deflandre et Cookson) Wall, Nematosphaeropsis labyrinthea (Ostenfeld) Reid and Dapsilidinium pastielsii were also recorded. Among the pollen grains Pinus is the predominant
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"1ERTIARY DINOFLAGELLATkCYSTS
component. Periporate pollen belonging to the Chenopodiaceae also were recorded in very low frequencies. The youngest stratigraphic occurrence of Invertoo'sta tabulata lies within Late Miocene sediments of the Rockall Plateau (Costa and Downie, 1979 as Forma A; Edwards, 1984) and in the Piedmont Tertiary Basin of Italy (Powell, 1986). A chomosphaera andalousiensis first occurs within Late Miocene deposits (Williams, 1975; Jan Du Chine, 1977; Harland, 1978; Piasecki, 1980; Benedek, 1980) and Middle/Late Miocene boundary (Brown and Downie, 1985; Jan Du Chine and Londeix, 1988; El-Beialy and Gheith, 1990). The presence of Achomosphaera andalousiensis in sample 3 of the Mit Ghamr-I well is considered here to define the base of Late Miocene. Reticulatosphaera actinocoronata is a worldwide marker for the Late Miocene age in Canada, Rockall Plateau, Denmark, Italy, the Netherlands and Egypt (Williams, 1975; Williams and Brideaux, 1975; Williams and Bujak, 1977; Barss et al., 1979; Costa and Downie, 1979; Piasecki, 1980; Powell, 1986; Herngreen, 1987; E1-Beialy, 1988a; El-Beialy and Gheith, 1990). Its presence indicates a Late Miocene age for sample 3.
265
The age previously assigned to sample 3 was Pliocene (IEOC, 1982) based on lithological evidence. My Late Miocene age determination is supported by the results of Zaghloul et al. (1979) who reported the presence of the Globorotalia ascostaensis and G. menardii foraminiferal Zones in the basal part of the Kafr E1 Sheikh Member II in the Kafr E1 Dawar-1 well, Nile Delta. All were assigned a Late Miocene age. Samples 2 and 1 (depth 749 m and 507 m)
Dinocysts are rare in both samples. Pteridophytic spores, Gramineae and Chenopodiaceae pollen are abundant. The only dinocyst represented is Tuberculodinium vancampoae (Rossignol) Wall. The latter species is not a useful index ranging from Late Oligocene to Pleistocene (Williams and Bujak, 1985). Comparison of this assemblage with that of Saad et al. (1987) from the Abu Qir-2X well, Nile Delta, of Plio-Pleistocene age, gives a similar age dating. In the absence of any evidence for a Pliocene age as given by the IEOC (1982), an age range for samples l and 2 from Pliocene to Quaternary is postulated.
PLATE 1 (All figures are approximately x 500, unless otherwise noted, the location of each figured specimen is given using the England Finder
references). I. 2. 3. 4. 5. 6, 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.
Achomosphaera andalousiensis Jan Du Ch6ne emend. Jan Du Ch6ne et Londeix, 1988, sample 3, Q29. Adnatosphaeridium reticulense (Pastiels) De Coninck, 1969, sample 7, Q40. Apectodinium homomorphum (Deflandre et Cookson) Lentin et Williams emend. Harland, 1979, sample 7, 037. Glaphyrocysta intricata (Eaton) Stover et Evitt, 1978, sample 6, E39. Diphyes colligerum (Deflandre et Cookson) Cookson 1965. sample 5, M45. Homotryblium tasmaniense Cookson et Eisenack 1967, sample 6, M24, W37. Stelladinium sp., sample 7, M35. lnvertoeysta tabulata Edwards, 1984, sample 3, P36. Charlesdowneia reticulata (Williams et Downie) Lentin et Vozzhennikova 1989, sample 6, V47. lmpagidinium patulum (Wall) Stover et Evin, 1978, sample 3, E27. Thalassiphora pelagica (Eisenack) Eisenack et Gocht emend. Benedek et Gocht, 1981, sample 6, L41. Nematosphaeropsis lativittalus Wrenn, 1988, sample 3, Q27. Echiperiporites estelae Germeraad et al., 1968, sample 4, $41. Chenopodiaceae pollen, sample 3, T38, x 750. Gramineae pollen, sample 1, x 57, x 750. Tuberculodinium vancampoae (Rossignol) Wall 1967, sample 2, J15. Reticulatosphaera actinocoronata (Benedek) Bujak et Matsuoka, 1986, sample 3, L30. Polypodiaceae (trilete spore), sample 1, D52. Riculacysta perforata Stover, 1977, sample 7, J39. Wetzeliella lunaris Gocht, 1969, sample 6, J29.
266
Conclusions Five distinctive dinocyst and pollen assemblages are d e f i n e d f r o m the M o k a t t a m , U n - n a m e d , Sidi Salem, K a f r E1 S h e i k h a n d the E1 W a s t a n i F o r m a t i o n s o f the M i t G h a m r - 1 well, Nile D e l t a , E g y p t . N o d i a g n o s t i c p a l y n o m o r p h a s s e m b l a g e is r e c o g n i s e d f r o m the Basal C h a l k F o r m a t i o n , t h u s p r e c l u d i n g its d a t i n g . I n t e r p r e t a t i o n s o f these a s e m b l a g e s yielded significant age d e t e r m i n a t i o n s as follows: (1) T h e M o k a t t a m F o r m a t i o n is o f M i d d l e a n d Late E o c e n e age as i n d i c a t e d by the I E O C (1982). (2) T h e s a m p l e f r o m w i t h i n the U n - n a m e d F o r m a t i o n is a s s i g n e d a n O l i g o c e n e - M i o c e n e age a n d n o t O l i g o c e n e as r e p o r t e d b y the I E O C (1982). (3) T h e b a s a l p a r t o f the K a f r E1 S h e i k h F o r m a t i o n is o f Late M i o c e n e age a n d n o t P l i o c e n e as g i v e n by the I E O C (1982). T h e o v e r l y i n g s a m p l e s f r o m the K a f r El S h e i k h a n d E1 W a s t a n i F o r m a t i o n s are o f P l i o c e n e - P l e i s t o c e n e age.
Acknowledgements T h e a u t h o r t h a n k s D r . J. W r e n n , A m o c o P r o d u c t i o n C o m p a n y , T u l s a , O K . , U . S . A . for s t i m u l a t i n g c o m m e n t s a n d critically r e a d i n g the m a n u s c r i p t . I a m also g r a t e f u l to the m a n a g e m e n t o f the I E O C for p r o v i d i n g the m a t e r i a l a n d well log n e c e s s a r y for this study.
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