Calcareous nannofossil biostratigraphy and ...

Calcareous nannofossil biostratigraphy and paleoecology of the Maastrichtian in the western coast of the Gulf of Suez, Egypt Medhat M. M. Mandur & Aly A. E. El Ashwah

Arabian Journal of Geosciences ISSN 1866-7511 Volume 8 Number 5 Arab J Geosci (2015) 8:2537-2550 DOI 10.1007/s12517-014-1364-4

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Author's personal copy Arab J Geosci (2015) 8:2537–2550 DOI 10.1007/s12517-014-1364-4

ORIGINAL PAPER

Calcareous nannofossil biostratigraphy and paleoecology of the Maastrichtian in the western coast of the Gulf of Suez, Egypt Medhat M. M. Mandur & Aly A. E. El Ashwah

Received: 7 December 2013 / Accepted: 5 March 2014 / Published online: 12 April 2014 # Saudi Society for Geosciences 2014

Abstract Calcareous nannofossil content of the Maastrichtian succession at the western coast of the Gulf of Suez in Egypt has been studied. This study aims to contribute in the understanding of high-resolution biostratigraphy and paleoecologic interpretations. Five biozones (Reinhardtites levis, Arkhangelskiella cymbiformis, Lithraphidites quadratus, Micula murus, and Micula prinsii) were distinguished. According to the paleoecologic parameters (cool-water, warm-water, productivity, preservation, and the ratio of Micula decussata/Watznaueria barnesae), the studied succession is subdivided into five ecozones. The environment of each ecozone is deduced; M. Prinsii, M. murus, and L. quadratus ecozones are characterized by a cooler climate, but R. levis and A. cymbiformis ecozones are characterized by a warmer climate.

Presently, there is no doubt about the presence of an extraterrestrial body impact in connection with the Maastrichtian, but total agreement does not exist among the authors to determine if there was one or several impacts keller et al. (2004). Today, coccolithophores live in the photic zone and are very sensitive to climatic/oceanographic changes. The calcareous nannofossil assemblages variations found in the geologic record thus reflected the changes of the photic zone. As a result, high-resolution analysis of the variations of calcareous nannofossil assemblages of the Maastrichtian has been provided by many authors (e.g., Perch-Nielsen 1969; Romein 1979; Perch-Nielsen et al. 1982; Monechi 1985; Jiang and Gartner 1986; Ehrendofer and Aubry 1992; Sheldon et al. 2010).

Keywords Maastrichtian . Nannofossil . Biostratigraphy . Paleoecology

Material and methods

Introduction The Maastrichtian is the best studied mass extinction event in the geologic record. The identification of the extinction pattern is essential to the determination of its causes. According to Pospichal (1996), a gradual or step extinction may result from long-term climatic and/or sea level changes, whereas an abrupt mass extinction may result from a catastrophic event such as an impact of a large asteroid Alvarez et al. (1980, 1984) or an intense volcanism Courtillot et al. (1988). M. M. M. Mandur (*) : A. A. E. El Ashwah Egyptian Petroleum Research Institute, Nasser City 11727 Cairo, Egypt e-mail: [email protected] A. A. E. El Ashwah e-mail: [email protected]

The aim of the present study is to document through the lithostratigraphy occurrence, biostratigraphy, and paleoecology of the Maastrichtian calcareous nannofossils of Wadi El Dakhl succession, which is delineated by latitude 28° 42′ N and longitude 32° 25′ E (Fig. 1). This study has been achieved through collecting 75 samples from the upper cretaceous of the studied area. These samples were treated to separate the calcareous nannofossil contents to get an idea about the widespread of the faunal assemblage in the western coast of the Gulf of Suez. The samples were processed as follows: 0.5 g of sediments was gently disaggregated in a mortar with 10 ml of distilled water. The obtained suspension was agitated several times in a tube and left to settle down 2 min. After this time, smear slides were prepared using Canada balsam. At least three traverses of the slides, corresponding to 450 fields of view, were examined in order to document species richness encountered during the analysis of one slide Gardin and Monechi (1998). The calcareous nannofossils counting were

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designated the type locality of the Sudr Chalk at Wadi Sudr, West Central Sinai. The lithology of the Sudr Formation at its type area is massive white and creamy chalk and chalky limestone bed with thin intercalations of light gray calcareous shale and argillaceous crystalline limestone. The Sudr Formation is subdivided into a Lower Markha Member and an Upper Abu Zenima Member. Generally, the Sudr Formation overlies the Matulla Formation and underlies the Esna Formation. In the present study, a considerable thickness of about 105 m of the Abu Zenima Member was measured. It consists of white and gray chalky limestone with argillaceous limestone intercalations and white chalk (Fig. 2).

Biostratigraphy Fig. 1 Location map of the studied succession

made at a magnification of ×2,500 (×100 oil objective with a ×2.5 additional lens). For the quantitative analyses, at least 300 specimens per sample were counted in randomly selected fields of view. In order to detect very rare species that could have important biostratigraphic and/or paleoecologic significance, the total calcareous nannofossil abundance was calculated as the number of specimens per field of view (SPP/FV) and the relative abundance of each individual taxon as the percentage from the total count. The species richness (diversity) is given as the total number of species recorded in each sample and used as a measure of the relative stability of ecological conditions (Watkins 1989). Preservation was estimated as good (G) for nannofossil specimens exhibit little or no overgrowth and/or dissolution; moderate (M) for some overgrowth and/or dissolution species; and poor (P) for strong overgrowth and/or dissolution species. Thoracosphaera operculata appeared often broken, and only fragments could be observed. In this we counted as one Thoracosphaera either a whole coccosphere or each three fragments bigger than 8 μm.

Lithostratigraphy The Upper Cretaceous rocks are well developed in Egypt. These sediments have attracted the attention of many stratigraphers and paleontologists because they are highly fossiliferous and well exposed. The studied area was subject to several studies (e.g., Strougo and Faris 1993; El Ashwah 1997; Scheibner et al. 2003). The studied succession of the Maastrichtian in the western coast of the Gulf of Suez in Egypt is assigned to the Sudr Formation (Abu Zenima Member). Ghorab (1961)

The calcareous nannofossils were separated from the studied samples which comprise 44 species. Some selected calcareous nannofossils are illustrated in Fig. 3. In the present study, the standard calcareous nannofossil zonations of Sissingh (1977) have been used in addition to some subdivisions (bioevents) proposed by Perch-Nielsen (1979, 1983). Five calcareous nannofossil biozones are recognized; these biozones are discussed herein, from base to top as follows: Reinhardtites levis zone The Reinhardtites levis zone (Sissingh 1977) spans the interval from the last occurrence of Tranolithus phacelosus to the last occurrence of R. levis. The last occurrence of R. levis coincides with the distinct and interregional increase in number of large Arkhangelskiella. In the present study, the R. levis zone includes the interval of total range of R. levis species. This zone is recorded in the Sudr Formation (Abu Zenima Member), and it attains about 39 m. In the investigation, the R. levis zone includes diversified calcareous nannofossil typical of the Maastrichtian and characterized by the presence of the following: Watznaueria barnesae, Arkhangelskiella cymbiformis, Arkhangelskiella specillata, Eiffelithus turriseiffelii, E. gorkae, Micula decussata, Micula concave, Cribrosphaerella ehrenbergii, Cribrosphaerella daniae, Placozygus sigmoides, Cyclagelosphaera reinhardtii, R. levis, Rhagodiscus angustus, Lithraphidites carniolensis, Microhabdulus decoratus, M. stradneri, Prediscosphaera grandis, Manivitella pemmatoides, Lucianorhabdus cayeuxii, Zygolithus crux, Kamptnerius punctatus, and Cribrocorona gallica (Fig. 4). According to its association of calcareous nannofossils, it is assigned to the Early Maastrichtian age. This zone is equivalent to that described by Eldeeb and El Gammal (1994); Mandur (2011); Guerra et al. (2012).

Author's personal copy

100

Sample No.

Lithology

Thickness (m) 105

Micula prinsii

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Arkhangelskiella cymbiformis zone

Calcareous nannofossil zones

Member

Formation

Age

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70

Chalky Limestone

68 Limestone

66

64

Micula murus

62 90 60

58

56 80

54

52

Lithraphidites quadratus

50

70

48

46

The Arkhangelskiella cymbiformis zone (Perch-Nielsen 1972), emended by (Sissingh 1977), spans from the last occurrence of R. levis to the first occurrence of Nephrolithus frequens. In the present study, the A. cymbiformis zone includes the interval from the last occurrence of R. levis to the first occurrence of Lithraphidites quadratus. There are several definitions attached to the name A. cymbiformis zone. Perch-Nielsen (1972) defined it as the interval from the last occurrence of R. anthophorus (meaning the form now described as R. levis) to the final occurrence of Micula murus or N. frequens. Martini (1976) defined it as the interval from the last occurrence of Q. trifidum to the final occurrence of L. quadratus. This zone in the present study is recorded from the Sudr Formation (Abu Zenima Member), and it attains about 12 m thick. The A. cymbiformis zone is characterized by the same assemblage of the previous zone in addition to the following forms: Prediscosphaera cretacea, Braarudosphaera bigelowii, Zeugrhabdotus amphipons, and Kamptnerius magnificus (Fig. 4). According its assemblage, it is assigned to the Early Maastrichtian age (Perch-Nielsen 1985; Mandur 2011; Guerra et al. 2012).

44

42

Lithraphidites quadratus zone

60

38

36

Arkhangelskiella cymbiforms

Abu-Zeneima

Sudr

Maastrichtian

40

50

34

32

30

40

28

26

24

22 30 20

According to C’epek and Hay (1969), it is defined as the interval from the first occurrence of L. quadratus to the first occurrence of N. frequens. In the present study, this zone includes the interval from the first occurrence of L. quadratus to the first occurrence of M. murus (PerchNielsen 1983, 1985). This zone is recorded from the Sudr Formation (Abu Zenima Member) with thickness of about 27 m. The L. quadratus zone is characterized by the same assemblage of the previous zone in addition to the following: Chiastozygus amphipons, L. quadratus, Prediscosphaera stoveri, Ahmuellerella octoradiata, Z. amphipons, and K. magnificus (Fig. 4). According to its association of calcareous nannofossil, this zone is assigned to the Early–Late Maastrichtian ages (Mandur 2011).

Reinhardtites levis

18

16 20

14

12

10

10

Micula murus zone

8

6

4

2 0

Fig. 2 General lithology, location of samples, and calcareous nannofossil zones of Wadi El Dakhl successtion

The M. murus zone (Bukry and Bramlette 1970; emended Perch Nielsen 1981), spans from the first occurrence of M. murus to the first occurrence of Micula prinsii. This zone is equivalent to the lower part of the N. frequens zone (C’epek and Hay 1969; emended Romein 1979). This zone is recorded from the Sudr Formation (Abu Zenima Member) with thickness of about 19.5 m. The M. murus zone is characterized by the following assemblage: W. barnesae, Arkhangelskiella cymbiformis, E. turriseiffelii, E. gorkae, M. decussata, M. murus, C. ehrenbergii, C. reinhardtii, R. angustus, L. carniolensis, L. quadratus, M. decoratus, P. grandis,


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2 1

3

11

16

21

26

31

8

13

12

18

17

23

22

32

P. cretacea, P. stoveri, C. gallica, C. amphipons, A. octoradiata, Ceratolithoides kamptneri, Cretarhabdus crenulatus, Octolithus multiplus, Zygodiscus sigmoides, and T. operculata (Fig. 4). It is assigned to the Late Maastrichtian age according to its association of calcareous nannofossil (Tantawy 2003; Zahran 2013).

10

14

19

24

29

28

27

5

9

7

6

4

33

34

15

20

25

30

35

Micula prinsii zone According to Perch-Nielsen (1979); emended Romein and Smit (1981), M. prinsii zone includes the interval from the first occurrence of M. prinsii to the first c o m m o n o c c u r r e n c e o f T. o p e r c u l a t a a n d

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Fig. 3

Light microscope photographs of calcareous nannofossil species. All figures ×2,500. 1–4 Micula concave Vebeek (1976b): 1, sample 12, Reinhardtites levis zone; 2, sample 32, Arkhangelskiella cymbiformis zone; 3, sample 35, Lithraphidites quadratus zone; 4,sample 46, Lithraphidites quadratus zone. 5, 6 Micula decussata Vekshina (1959): 5, sample 60, Micula murus zone; 6, sample 69, Micula prinsii zone. 7– 10 Micula murus Bukry (1973): 7, sample 53, Micula murus zone; 8, sample 65, Micula murus zone; 9, sample 64, Micula murus zone; 10, sample 68, Micula prinsii zone. 11 Micula prinsii Perch-Nielsen (1979a): sample 69, Micula prinsii zone. 12, 13 Eiffelithus turriseiffelii Reinhardt (1965): 12, sample 23, Reinhardtites levis zone; 13, sample 32, Arkhangelskiella cymbiformis zone. 14–18 Arkhangelskiella cymbiformis Vekshina (1959): 14, sample 26, Reinhardtites levis zone; 15, sample 30, Arkhangelskiella cymbiformis zone; 16, sample 38, Lithraphidites quadratus zone; 17, sample 60, Micula murus zone; 18, sample 66, Micula prinsii zone. 19, 20 Arkhangelskiella specillata Vekshina (1959): 19, sample 67, Micula prinsii zone; 20, sample 70, Micula prinsii zone. 21–23 Reinhardtites levis Repagalum Forchheimer (1972): 21, samples 23 and 26, Reinhardtites levis zone. 24 Zeugrhabdotus embergeri Perch-Nielsen (1984): sample 51, Lithraphidites quadratus zone. 25 Placozygus sigmoides Podorhabdus Noél (1965): sample 29, Arkhangelskiella cymbiformis zone. 26 Rhagodiscus angustus Reinhardt (1971): sample 59, Micula murus zone. 27 Thoracosphaera operculata Bramlette and Martini (1964): sample 70, Micula prinsii zone. 28 Lithraphidites quadratus Bramlette and Martini (1964): sample 37, Lithraphidites quadratus zone. 29, 30 Microhabdulus decoratus Vekshina (1959): 29, sample 33, Arkhangelskiella cymbiformis zone; 30, sample 65, Micula murus zone. 31–35 Watznaueria barnesae Perch-Nielsen (1968): 31, 32, samples 5 and 22, Reinhardtites levis zone; 33, sample 27, Arkhangelskiella cymbiformis zone; 34, sample 48, Lithraphidites quadratus zone; 35,sample 55, Micula prinsii zone

Thoracosphaera spp. This zone is equivalent to the upper part of N. frequens zone (C’epek and Hay 1969; emended Romein 1979). In the present study, this zone is defined by the occurrence of M. prinsii. This zone is recorded from the Sudr Formation (Abu Zenima Member) with thickness of about 7.5 m. In the investigated area, the M. prinsii zone includes typical calcareous nannofossil assemblage similar to that of the previous zone in addition to M. prinsii (Fig. 4). According to its association, this zone is assigned to the Late Maastrichtian age (Tantawy 2003).

Paleoecology Calcareous nannoplankton are one of the most important primary producers in the oceans, contributing to global carbon cycle both as a biological pump and carbonate pump. Living calcareous nannoplankton are largely controlled by water mass conditions (Mcintyre 1967). In modern seas, nannoplankton composition is a good indicator of water mass conditions and ecology, while calcareous nannoplankton has been also used to decipher the paleoecologic conditions in the ancient oceans.

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The following gives a brief overview of the different paleoecologic indicators used in this study. It includes their meaning and their application for the interpretation of paleoenvironments and paleobathymetry. Cool-water nannofossil indicators A. octoradiata and K. magnificus are common in high latitudes during the Cretaceous (Pospichal and Wise 1990). L. cayeuxii and Arkangelskiella cymbiformis were also found in fair abundances in the mid to high latitudes (Thierstein 1976, 1981; Lees 2002). P. stoveri is generally interpreted as high latitude (Sheldon et al. 2010; Guerra et al. 2012). M. decussata, M. concave, K. magnificus, A, specillata, R. levis, P. grandis, Prediscosphaera spinosa, and P. cretacea, these are cool-water taxa, which is the commonest at high latitudes, although it has been recorded at low latitudes as well. It is considered as a cosmopolitan species (Ovechkina and Alekseev 2004; Sheldon et al. 2010). The cool water indices are presented both as a group and separately (Fig. 5) in order to illustrate their contrasting trends, perhaps indicative of their individual response to the temperature gradient. In the present study, in the R. levis zone, the cool-water (high latitude) nannofossil are represented by an average of 36 %. They fluctuated between 11 and 54 %, and the predominantly represented by M. decussata is found in abundance of 11 %. The cool-water species Arkhangelskiella cymbiformis is relatively abundant in the R. levis zone (22 %). In the A. cymbiformis zone, the high-latitude nannofossil indicators (cool-water nannofossil species) are represented by 37 % of the total nannofossil assemblages. The average abundances of the M. decussata and Arkhangelskiella cymbiformis in this zone are 0.05 and 18 %, respectively, of the total nannofossil assemblages. The L. quadratus zone is characterized by relatively abundance of 49 % of cool-water species, 15 % of M. decussata, and 21 % of Arkhangelskiella cymbiformis of the total nannofossil assemblages. Cool-water nannofossil in the M. murus zone comprises up to about 62 %. The coolwater taxon M. decussata and Arkhangelskiella cymbiformis are present in abundance of 24 and 24 %, respectively, of the total nannofossil assemblages. In the M. prinsii zone, the highlatitude (cool-water) nannofossil shows high abundance of 56 % and the abundance of cool-water species, M. decussata, and Arkhangelskiella cymbiformis are 34 and 0.06 %, respectively, (Figs. 7 and 8). Warm-water nannofossil indicators A number of low-latitude taxa, e.g., M. murus, M. prinsii, and Ceratolithoides spp., have applied as proxies for warm temperatures, but in general, they are absent in the chalk. In the absence of these low-latitude taxa, W. barnesae appears to be a


8 3 0 1 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 2 1 1 0 1 0 0 2 0 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

15 10 8 5 9 2 1 0 0 0 0 0 1 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 3 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Calculites obscurus

2 3 7 6 8 9 2 1 1 0 2 2 6 3 1 6 5 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Arkhangeleskiella specillata

1 2 0 0 1 1 0 0 0 0 0 1 0 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Micula prinsii*

5 1 3 2 0 1 1 1 1 2 1 1 0 0 2 5 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Ceratolithoides aculeus

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 2 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Biscutum constant

6 0 6 0 18 2 5 11 8 8 1 6 0 3 0 4 0 0 0 0 1 0 1 6 0 0 0 0 1 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 2 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Thoracosphaera operculata

1 1 1 3 6 2 3 1 4 2 5 5 3 2 3 1 1 1 1 1 0 1 1 1 1 1 3 2 2 2 1 0 2 2 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Zygodiscus sigmoides

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cretarhabdus crenulatus

3 14 6 3 5 0 4 8 6 2 4 2 1 1 1 6 12 13 0 1 1 3 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Octolithus multiplus

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Micula murus*

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Ceratolithoides kamptneri

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 13 5 0 0 0 o 2 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Ahmuellerella octoradiata

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Prediscosphaera spinosa

1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lithraphidites quadratus*

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 3 0 0 0 1 0 0 0 0 1 0 0 1 1 1 0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Prediscosphaera stoveri

4 12 9 11 38 45 2 4 2 7 5 8 2 5 7 16 11 22 5 4 1 4 4 3 2 5 18 3 1 1 1 4 3 2 5 1 0 0 3 4 2 5 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cretarhabdus conicus

0 0 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 2 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Chiastozygus amphipons

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Manivitella pemmatoides

9 0 10 0 15 5 33 7 27 1 13 0 11 10 15 3 12 5 2 2 3 2 7 6 8 5 11 4 13 4 10 2 2 4 5 3 0 0 0 0 3 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 0 0 0 0

Zeugrhabdotus embergeri

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 0 0

Kamptnerius punctatus

0 0 1 0 1 6 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 1 1 1 2 1 0 0

Kamptnerius magnificus

Braarudosphaera bigelowii

1 1 3 2 1 2 1 1 3 0 0 0 4 0 3 0 0 4 0 1 0 0 0 1 1 2 1 1 0 0 3 2 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Zeugrhabdotus amphipons

1 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 1 0 2 1 1 1 0 0 0 2 2 3 1 1 1 4 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Prediscosphaera cretacea

2 1 1 8 2 13 2 3 3 0 5 2 7 6 2 3 2 6 0 0 0 0 0 0 2 2 1 1 1 1 3 0 1 1 0 2 17 16 2 1 0 0 17 20 16 13 2 1 0 0 0 0 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cribrosphaerrella daniae

2 0 6 0 9 0 2 0 1 0 1 0 3 0 2 0 7 0 1 0 2 0 3 0 5 0 6 0 7 0 4 0 8 0 8 0 0 0 5 0 2 0 1 0 0 0 1 0 3 1 1 0 1 0 11 1 1 0 1 1 2 1 1 0 11 0 12 0 2 0 1 1 0 1 2 1 1 1 1 2 0 0 1 0 3 0 1 0 1 1 1 1 1 2 1 1 1 0 0 16 1 0 1 0 0 0 0 0 0 1 0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Reinhardtites levis *

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 2 1 0 0 0 0 0 0 0 0 0 2 0 1 0 0 1 2 1 1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Prediscosphaera grandis

0 0 0 3 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 3 1 1 1 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 3 15 0 0 0 1 1 2 5 0 0 0 0 0 0 0 0

Rhagodiscus angustus

Microhabdulus decoratus

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 1 1 1 0 3 1 1 1 1 1 0 0 0 0 2 3 1 1 3 1 0 1 1 1 0 0 0 0 0 0 1 0 0 0 4 1 1 3 1 1 1 5 2 3 2 1 1 1 2 6

Eiffelithus gorkae

Microrhabdulus stradneri

12 11 5 6 16 14 17 26 15 21 34 31 11 13 19 22 27 19 0 29 21 23 5 4 2 4 1 24 6 21 3 2 1 1 1 0 0 4 16 19 21 3 2 11 16 5 4 3 2 18 16 15 25 4 21 17 13 3 2 1 1 0 3 1 12 15 17 23 16 22

Zygolithus crux

Lithraphidites carniolensis

121 126 151 103 81 61 62 37 38 27 71 70 36 35 101 70 63 69 5 3 22 25 5 6 27 28 21 25 5 27 23 5 16 15 17 4 3 5 9 16 2 1 3 2 1 3 2 1 0 4 5 2 11 21 15 28 27 28 5 1 3 3 19 17 3 1 1 1 4 2

Lucianorhabdus cayeuxii

Placozygus sigmoides

4 1 1 11 7 8 1 1 2 1 3 1 0 1 0 0 0 5 4 3 2 4 1 1 3 17 3 1 4 18 2 4 19 11 21 3 1 0 5 1 2 1 4 0 9 8 2 16 12 10 8 2 1 0 3 6 1 0 2 0 0 0 1 5 2 4 1 1 1 1

Cribrocorona gallica

Cyclagelosphaera reinhardtii

10 14 25 20 31 45 50 85 61 55 65 61 45 51 35 30 45 83 4 20 23 26 5 9 15 11 13 16 30 61 29 16 18 28 25 27 4 21 55 14 29 11 9 12 21 19 27 33 11 14 9 28 16 21 5 4 3 1 27 21 19 16 59 60 30 31 8 9 11 13

Micula concava

40 61 50 41 35 31 28 25 10 21 33 30 10 15 13 50 30 26 5 4 3 20 19 18 18 20 21 22 25 19 15 11 22 13 12 8 16 13 5 11 35 34 58 62 15 14 12 11 13 11 8 15 16 20 24 16 19 24 22 24 18 13 32 31 14 29 33 10 12 15

Cribrosphaerella ehrenbergii

293 354 377 329 326 293 230 242 180 166 270 269 156 170 228 279 243 295 33 78 83 130 62 63 104 130 120 134 101 176 101 60 121 107 104 61 64 81 112 87 134 98 157 174 100 82 69 85 55 88 59 84 88 90 112 90 84 84 82 73 62 57 149 149 78 112 98 59 58 74

Eiffelithus turriseiffelii

Arkhangeleskiella cymbifornis

G G G G G G G G M M G G M M G G G G M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M

Micula decussata

Watznaueria barnesae

A A A A A A A A F F A A F F A A A A C C C F C C C F C F C F C C C C C C C C F C F C F F C C C C C C C C C C C C C C C C C C F F C C C C C C

Preservation

Abundance

70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

Total

Sample No.

Micula prinsii Zone

Reinhardtites levis

Arkhangelskiella cymb

Sudr

Maastrichtian


Micula murus

Age

Arab J Geosci (2015) 8:2537–2550

Formation

2542

0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Fig. 4 Calcareous nannofossil assemblage abundance , preservation and species richness data from the Wadi El Dakhl succession

useful proxy in any studied. Although this species was a longlived and widely distributed taxon by the Late Cretaceous, its biogeography is considered by many nannofossil workers to reflect a preference for warmer temperatures (Bukry 1973); (Huber and Watkins 1992). It has been used as a warm-water indicator in a number of the Maastrichtian studies (Thibault and Gardin 2007). It should be noted that some studies have related W. barnesae fluctuations to trophic variation rather than to temperature, typically in the Mid-Cretaceous sections

recording marked shifts in nutrient supply (Erba et al. 1992). At the same time, assumptions have been made that the proportion of W. barnesae increases under low productivity conditions (Erba et al. 1992) or that it is an ecologically tolerant species which occupies new ecological niches first (Mutterlose 1996). However neither interpretation implies that W. barnesae is indifferent to temperature; on the contrary, available data show rarity or complete absence of this species at high latitudes (Pospichal and Wise 1990; Resiwati 1991;


Watkins 1992). W. barnesae is the main warm-water species. Ceratolithoides aculeus, species of the genera Lithraphidites (L. carniolensis and L. quadratus), M. murus, M. prinsii, Biscutum constans, Cretarhabdus surirellus, and O. multiplus should be also considered as warm-water species (Fig. 5) (Ovechkina and Alekseev 2004). The warm-water coefficient for each sample was evaluated as the percentage of warm-water taxa in the assemblage for each sample (Figs. 7 and 8). In the present study, in the R. levis zone, the warm-water (low-latitude taxa) trend to increase from 13 to 25 % with an average of 22 % of the total nannofossil assemblages. W. barnesae in this zone has an average of 21 %; it fluctuates between 13 and 34 % of the total nannofossil assemblages. The low-latitude taxa are present in an average of 26 % and peak abundances of 38 % are recorded in the Arkhangelskiella cymbiformis zone. Three well-develop peaks of W. barnesae are observed at the A. cymbiformis zone; the lower peak occurred in the middle with an average of 37 %. The averages of warm-water taxa and W. barnesae in the L. quadratus zone are 18 and 16 %, respectively. The M. murus zone is characterized by relatively abundance of 14 % of warm-water species and 10 % of W. barnesae. The M. prinsii zone is represented by an average of 21 % of the warm-water (low-latitude) calcareous nannofossil taxa. They fluctuated between 18 and 26 % of the total nannofossil assemblages, and the abundance of warm-water species W. barnesae is 13 % (Figs. 7 and 8).

Productivity indicators The relationship between calcareous nannoplankton and various studies of both the living and fossil records was discussed. Young (1994) indicated that in normal marine conditions, the nannoplankton population increases with productivity but that in extreme eutrophic environments, the population is suppressed and decreases significantly. Watkins (1989) reported that nannofossil assemblages showed increase in abundance and diversity in intervals that were deposited under low productivity conditions, whereas in intervals that represented enhanced productivity, the nannofossil assemblages were impoverished. Eshet and Almogi Labin (1996) indicated that nannofossils reach their highest species and abundance in intervals of lowered productivity. Conversely, abundance and diversity decline in intervals of the heightened productivity. They suggested that intervals of low productivity are characterized by high calcareous nannofossil abundance and diversity. It includes the following taxa: P. spinosa, P. cretacea, E. turriseiffelii, L. carniolensis, and T. operculata. They also suggested that the high productivity is characterized by a lower nannofossil abundance and species diversity. It includes the following taxa: L. quadratus and B. constans (Fig. 6).

2543

The high productivity taxa are generally low in abundance throughout the sections fluctuating from 0.01 to 0.05 % of the total assemblage in the upper part of the succession (L. quadratus, M. murus, and M. prinsii zones). The low productivity taxa show fluctuating distributions and they are higher in abundance than the higher productivity taxa. It is fluctuating from 0.05 to 14 % throughout the section. Two well-developed peaks of low productivity taxa are observed 14 and 10 % in L. quadratus and M. prinsii zones, respectively (Figs. 7 and 8). Nannofossils preservation and the abundance of Micula decussata High abundance of the robust nannofossil M. decussata (Micula staurophora) of some workers has been cited as an indication of poor preservation (Thierstein 1976, 1980; Eshet and Almogi Labin 1996), but when preservation is not the overriding control on its abundance, it may provide important paleoenvironmental information. M. decussata has been a major constituent of the Late Cretaceous tropical and subtropical assemblages (Thierstein and Haq 1977; Wind 1979). In fact, its distribution may be the result of latitudinal preservation patterns possibly related to fertility. According to Thierstein (1980, 1981) and Guerra et al. (2012), M. decussata is a highly dissolution resistance form and is considered as a good indicator of poor nannofossil preservation and diagenetic enhancement (Roth 1983). In the present study, the high abundance of M. decussata does not appear to be an artifact of dissolution because most of other species including dissolution prone forms (e.g., B. constans, P. cretacea, and C. ehrenbergii) are well preserved. Moshkovitz and Eshet (1989) distinguished that the M. decussata is good preservation and no evidence of strong dissolution or overgrowth. Hence, the high abundances of M. decussata are well-preserved assemblages in the present study, reflect a natural increase in abundance, (Pospichal 1991) due to high-stress marine environments (Eshet et al. 1992). The preservation of the samples considered in this study is moderate at the lower part of the section. During the Late Maastrichtian, the M. murus and M. prinsii zones are characterized by fluctuating from good to moderate preservation. The M. decussata shows fluctuating distribution from 0.5 to 34 %. Although there are occasional peaks up to 34 %, M. decussata generally demonstrates stable moderate abundances throughout the lower parts of the studied succession, but it begins to increase steadily within the M. murus and M. prinsii zones (Figs. 7 and 8). The ratio of Micula decussata/Watznaueria barnesae Beside the percentage of warm- and cool-water forms, such an important criterion as the ratio of M. decussata/W. barnesae is


Arab J Geosci (2015) 8:2537–2550

Kamptnerius magnificus

Kamptnerius punctatus

Cribrocorona gallica

Total

Micula murus

Micula prinsii

Ceratolithoides kamptneri

Ceratolithoides aculeus

Watznaueria barnesae


Cretarhabdus crenulatus

Braarudosphaera bigelowii

Biscutum constant

Octolithus multiplus


Zeugrhabdotus amphipons

Total

6

2

0

121

0

0

0

9

0

4

1

157

5

0

1

1

40

1

2

1

1

8

15

0

75

0

6

1

0

126

0

0

0

10

0

12

1

178

1

1

2

1

61

1

3

1

3

3

10

0

87

68

2

1

9

25

1

18

1

0

151

0

0

0

15

0

9

3

235

3

0

0

0

50

1

7

1

0

0

8

0

70

67

11

0

2

20

1

5

8

0

103

0

0

0

33

0

11

2

196

2

0

0

0

41

3

6

0

1

1

5

0

59

66

8

0

1

31

0

8

2

0

81

0

0

0

27

0

38

1

197

0

1

1

0

35

6

8

0

2

1

9

0

63

65

6

0

1

45

0

1

13

0

61

0

0

0

13

0

45

2

187

1

0

1

0

31

2

9

0

0

0

2

0

46

64

3

0

3

50

0

0

2

0

62

0

0

0

11

0

2

1

134

1

0

0

0

28

3

2

0

0

0

1

0

35

63

4

0

2

85

0

0

3

0

37

0

0

0

15

0

4

1

151

1

0

0

0

25

1

1

0

0

0

0

0

28

62

0

0

7

61

0

0

3

0

38

0

0

0

12

0

2

3

126

1

0

0

0

10

4

1

0

0

0

0

0

16

61

0

0

1

55

0

0

0

0

27

0

0

0

2

0

7

0

92

2

0

0

0

21

2

0

0

0

0

0

0

25

60

0

0

2

65

0

1

5

0

71

0

0

0

3

0

5

0

152

1

0

0

0

33

5

2

0

0

1

0

0

42

59

6

0

3

61

0

0

2

0

70

0

0

0

7

0

8

0

157

1

0

1

0

30

5

2

0

0

0

0

0

39

58

0

0

5

45

0

0

7

0

36

0

0

0

8

0

2

4

107

0

0

0

0

10

3

6

0

0

0

1

0

20

57

0

0

6

51

0

0

6

0

35

0

0

0

11

0

5

0

114

0

0

2

0

15

2

3

0

0

0

0

0

22

56

0

0

7

35

0

1

2

0

101

0

0

0

13

0

7

3

169

2

0

2

0

13

3

1

0

0

0

1

0

22

55

0

0

4

30

0

2

3

0

70

0

0

0

10

0

16

0

135

5

0

0

0

50

1

6

0

0

0

2

0

64

54

0

0

8

45

0

0

2

0

63

1

0

0

2

0

11

0

132

2

0

0

0

30

1

5

0

0

0

0

0

38

53

0

0

8

83

0

0

6

0

69

1

0

0

5

0

22

4

198

1

0

0

0

26

1

3

0

0

0

0

0

31

52

0

0

0

4

0

0

0

2

5

0

0

0

0

0

5

0

16

0

0

0

0

5

1

0

0

0

0

0

0

6

51

0

0

5

20

0

0

0

1

3

0

0

0

0

0

4

1

34

0

0

0

0

4

1

0

0

0

0

0

0

5


Micula decussata

1

14


Micula concava

10

6

Prediscosphaera grandis

Microhabdulus decoratus

2

2

Reinhardtites levis

Prediscosphaera stoveri

Arkhangeleskiella specillata

Arkhangeleskiella cymbifornis

1

0


0

69

Lucianorhabdus cayeuxii

Sample No.

Ahmuellerella octoradiata

Zone

Reinhardtites levis


Warm water

70

50

0

0

2

23

0

0

0

1

22

0

0

0

3

0

1

0

52

0

0

0

0

3

0

0

0

0

0

0

0

3

49

0

0

1

26

0

0

0

1

25

0

0

0

0

0

4

0

57

0

0

0

0

20

1

0

0

0

0

0

0

21

48

0

0

0

5

0

0

0

1

5

0

0

0

1

0

4

0

16

0

0

0

0

19

1

0

0

0

0

0

0

20

47

0

0

1

9

0

0

0

0

6

0

0

0

1

0

3

1

21

0

0

0

0

18

1

0

0

0

0

0

0

19

46

1

0

3

15

0

1

2

3

27

0

0

0

0

4

2

1

59

0

0

0

0

18

1

0

0

0

0

0

0

19

45

0

0

1

11

0

1

2

1

28

13

0

0

0

2

5

2

66

0

0

0

0

20

1

0

0

0

0

0

1

22

44

0

0

1

13

0

2

1

1

21

5

1

0

0

1

18

1

65

0

0

0

0

21

3

0

0

0

0

0

1

25

43

0

0

11

16

0

0

1

1

25

0

0

0

0

0

3

1

58

0

0

0

0

22

2

0

0

0

0

0

3

27

42

0

0

1

30

0

0

1

1

5

0

0

0

0

0

1

0

39

0

0

0

0

25

2

0

0

0

0

0

0

27

41

0

0

1

61

0

0

1

1

27

0

0

0

3

0

1

0

95

0

0

0

0

19

2

0

0

0

0

0

0

21 16

40

0

0

2

29

0

1

3

0

23

o

0

0

0

1

1

3

63

0

0

0

0

15

1

0

0

0

0

0

0

39

0

0

1

16

0

0

0

0

5

2

0

0

0

0

4

2

30

0

0

0

0

11

0

0

0

0

0

0

1

12

38

0

0

11

18

0

0

1

0

16

0

0

0

0

0

3

1

50

0

0

0

0

22

2

0

1

0

0

0

0

25

28

0

0

0

3

12

0

15

62

0

0

13

36

0

0

2

25

0

0

0

2

17

0

1

0

0

0

5

0

52

0

0

0

0

12

1

0

1

0

0

0

0

14

35

0

0

1

27

0

0

2

3

4

0

0

0

0

0

1

0

38

0

0

0

0

8

1

0

1

0

0

0

0

10

37

Sudr

Maastrichtian


Micula murus

Micula prinsii

Formation

Age

Cool water

1

0

0

0

0

0

2

1

0

0

2

0

1

0

0

0

0

16

34

0

1

0

4

0

0

17

1

3

1

0

0

0

0

0

0

27

0

0

0

0

16

0

0

1

0

0

0

1

18

33

0

0

2

21

0

0

16

1

5

0

0

0

0

0

0

0

45

0

0

0

0

13

0

0

1

0

0

0

0

14

32

0

2

1

55

0

0

2

3

9

0

0

0

0

0

3

0

75

0

0

0

0

5

0

0

1

0

0

0

0

6

31

0

1

1

14

0

0

1

1

16

0

0

0

0

0

4

0

38

0

0

0

0

11

0

0

1

0

0

0

1

13

30

0

1

0

29

0

0

0

0

2

0

1

0

0

0

2

0

35

0

0

0

0

35

0

0

1

0

0

0

1

37

29

0

1

1

11

0

0

0

1

1

0

0

0

0

0

5

0

20

0

0

0

0

34

0

0

2

0

0

0

1

37

28

0

0

3

9

0

0

17

1

3

0

0

0

0

0

1

0

34

0

0

0

0

58

0

0

0

0

0

0

0

58

27

0

0

1

12

0

0

20

1

2

0

0

0

0

0

0

0

36

0

0

0

0

62

0

0

0

0

0

0

1

63

26

0

0

1

21

0

0

16

0

1

0

1

1

0

0

0

0

41

0

0

0

0

15

0

0

0

0

0

0

1

16

25

0

2

1

19

0

0

13

0

3

0

0

0

0

0

0

0

38

0

0

0

0

14

0

0

0

0

0

0

0

14 13

24

0

2

1

27

0

0

2

0

2

0

0

1

0

0

0

0

35

0

0

0

0

12

0

0

0

0

0

0

1

23

0

3

1

33

0

0

1

0

1

0

0

2

0

0

0

1

42

0

0

0

0

11

0

0

0

0

0

0

0

11

22

0

1

1

11

0

0

0

0

0

0

0

0

0

0

0

1

14

0

0

0

0

13

0

0

0

0

0

0

0

13 11

21

0

1

1

14

0

0

0

0

4

0

0

0

0

0

0

0

20

0

0

0

0

11

0

0

0

0

0

0

0

20

0

1

1

9

0

0

0

1

5

0

0

0

0

0

0

0

17

0

0

0

0

8

0

0

0

0

0

0

0

8

19

0

4

1

28

0

0

0

0

2

0

0

0

0

0

0

0

35

0

0

0

0

15

0

0

0

0

0

0

0

15

18

0

1

0

16

0

0

2

0

11

0

0

0

0

0

0

0

30

0

0

0

0

16

0

0

0

0

0

0

0

16

17

0

0

0

21

0

0

1

0

21

0

0

0

0

0

0

0

43

0

0

0

0

20

0

0

0

0

0

0

0

20

16

0

0

0

5

0

0

0

4

15

0

0

0

0

0

0

0

24

0

0

0

0

24

0

0

0

0

0

0

0

24

15

0

0

0

4

0

0

0

1

28

0

0

0

0

0

0

0

33

0

0

0

0

16

0

0

0

0

0

0

0

16

14

0

0

1

3

0

0

0

1

27

0

0

0

0

0

0

0

32

0

0

0

0

19

0

0

0

0

0

0

0

19

13

0

0

1

1

0

0

0

3

28

0

0

0

0

0

0

0

33

0

0

0

0

24

0

0

0

0

0

0

0

24

12

0

0

0

27

0

0

0

1

5

0

0

0

0

0

0

0

33

0

0

0

0

22

0

0

0

0

0

0

0

22

11

0

0

0

21

0

0

0

1

1

0

0

0

0

0

0

0

23

0

0

0

0

24

0

0

0

0

0

0

0

24

10

0

0

0

19

0

0

0

1

3

0

0

0

0

0

0

0

23

0

0

0

0

18

0

0

0

0

0

0

0

18

9

0

0

0

16

0

0

0

5

3

0

0

0

0

0

0

0

24

0

0

0

0

13

0

0

0

0

0

0

0

13

8

0

0

0

59

0

0

0

2

19

0

0

0

0

0

0

0

80

0

0

0

0

32

0

0

0

0

0

0

0

32

7

0

0

0

60

0

0

0

3

17

0

0

0

0

0

0

0

80

0

0

0

0

31

0

0

0

0

0

0

0

31

6

0

0

0

30

0

0

0

2

3

0

0

0

0

0

0

0

35

0

0

0

0

14

0

0

0

0

0

0

0

14

5

0

0

0

31

0

0

0

1

1

0

0

0

0

0

0

0

33

0

0

0

0

29

0

0

0

0

0

0

0

29

4

0

0

0

8

0

0

0

1

1

0

0

0

1

0

0

33

0

11

0

0

0

0

33

0

0

0

0

0

0

0

3

0

0

0

9

0

0

0

1

1

0

0

0

1

0

0

0

12

0

0

0

0

10

0

0

0

0

0

0

0

2

0

0

0

11

0

0

0

2

4

0

0

0

0

0

0

0

17

0

0

0

0

12

0

0

0

0

0

0

0

12

1

0

0

0

13

0

0

0

6

2

0

0

0

0

0

0

0

21

0

0

0

0

15

0

0

0

0

0

0

0

15

Fig. 5 Calcareous nannofossil cool- and warm-water species richness data from the Wadi El Dakhl succession

10


2545



Eiffelithus gorkae

Eiffelithus turriseiffelii



Total


Biscutum constant

Total

High productivity

70

4

0

0

4

2

15

25

1

1

2

69

12

0

0

1

6

10

29

1

3

4

68

9

0

1

1

9

8

28

1

0

1

67

11

0

0

11

2

5

29

3

1

4

66

38

0

1

7

1

9

56

6

2

8

65

45

0

6

8

1

2

62

2

0

2

64

2

0

0

1

3

1

7

3

0

3

63

4

0

0

1

2

0

7

1

0

1

62

2

0

0

2

7

0

11

4

0

4

61

7

0

0

1

1

0

9

2

0

2

60

5

0

0

3

2

0

10

5

0

5

59

8

0

0

1

3

0

12

5

0

5

58

2

0

1

0

5

1

8

3

0

3

57

5

0

0

1

6

0

12

2

0

2

56

7

0

0

0

7

1

15

3

0

3

55

16

0

0

0

4

2

22

1

0

1

54

11

0

0

0

8

0

19

1

0

1

53

22

0

0

5

8

0

35

1

0

1

52

5

0

0

4

0

0

9

1

0

1

51

4

0

0

3

5

0

12

1

0

1

50

1

0

0

2

2

0

5

0

0

0

49

4

0

0

4

1

0

9

1

0

1

48

4

0

0

1

0

0

5

1

0

1

47

3

0

0

1

1

0

5

1

0

1

46

2

4

0

3

3

0

12

1

0

1

45

5

2

1

17

1

0

26

1

0

1

44

18

1

1

3

1

0

24

3

0

3

43

3

0

1

1

11

0

16

2

0

2

42

1

0

0

4

1

0

6

2

0

2

41

1

0

0

18

1

0

20

2

0

2

40

1

1

0

2

2

0

6

1

0

1

39

4

0

0

4

1

0

9

0

0

0

38

3

0

0

19

11

0

33

2

0

2

37

2

0

0

11

12

0

25

2

0

2

36

5

0

0

21

2

0

28

1

0

1

35

1

0

0

3

1

0

5

1

0

1

34

0

0

0

1

0

0

1

0

0

0

33

0

0

1

0

2

0

3

0

0

0

32

3

0

1

5

1

0

10

0

0

0

31

4

0

1

1

1

0

7

0

0

0

30

2

0

1

2

0

0

5

0

0

0

29

5

0

1

1

1

0

8

0

0

0

28

1

0

0

4

3

0

8

0

0

0

27

0

0

0

0

1

0

1

0

0

0

26

0

0

0

9

1

0

10

0

0

0

25

0

0

0

8

1

0

9

0

0

0

24

0

0

0

2

1

0

3

0

0

0

23

0

0

0

16

1

0

17

0

0

0

22

0

0

0

12

1

0

13

0

0

0

21

0

0

0

10

1

0

11

0

0

0

20

0

0

0

8

1

0

9

0

0

0

19

0

0

0

2

1

0

3

0

0

0

18

0

0

0

1

0

0

1

0

0

0

17

0

0

0

0

0

0

0

0

0

0

16

0

0

0

3

0

0

3

0

0

0

15

0

0

0

6

0

0

6

0

0

0

14

0

0

0

1

1

0

2

0

0

0

13

0

0

0

0

1

0

1

0

0

0

12

0

0

0

2

0

0

2

0

0

0

11

0

0

0

0

0

0

0

0

0

0

Sample No.

Zone

Reinhardtites levis


Sudr

Maastrichtian


Micula murus

Micula prinsii

Formation

Age

Low productivity

10

0

0

0

0

0

0

0

0

0

0

9

0

0

2

0

0

0

2

0

0

0

8

0

0

1

1

0

0

2

0

0

0

7

0

0

1

5

0

0

6

0

0

0

6

0

0

1

2

0

0

3

0

0

0

5

0

0

1

4

0

0

5

0

0

0

4

0

0

2

1

0

0

3

0

0

0

3

0

0

1

1

0

0

2

0

0

0

2

0

0

0

1

0

0

1

0

0

0

1

0

0

0

1

0

0

1

0

0

0

Fig. 6 Calcareous nannofossil low-productivity and high-productivity species richness data from the Wadi El Dakhl succession


Sample No.

Total

Cool water %

Micula decussata%

Arkhangeleskiella cymbifornis %

Warm water %

Watznaueria barnesae. %

High productivity indicators %

Low productivity indicators %

Micula decussata / Watznaueria barnesae

Zone Reinhardtites levis CC24

Arkhangelskiella cymbiforms CC 25 a

Sudr

Maastrichtian

Lithraphidites quadratus CC 25 b

Micula murus CC 25 c

Micula prinsii CC26

Formation

Arab J Geosci (2015) 8:2537–2550

Age

2546

70

293

0.54

0.41

0.03

0.26

0.14

0.07

0.09

3

69

354

0.5

0.36

0.04

0.25

0.17

0.01

0.08

2

68

377

0.62

0.4

0.07

0.19

0.13

0.003

0.07

3

67

329

0.55

0.31

0.06

0.18

0.12

0.12

0.09

2.5

66

326

0.6

0.24

0.1

0.19

0.11

0.02

0.17

2.3

65

293

0.64

0.21

0.15

0.16

0.1

0.01

0.21

1.9

64

230

0.58

0.27

0.22

0.15

0.12

0.01

0.03

2.2

63

242

0.62

0.15

0.35

0.12

0.1

0.004

0.03

1.5

62

180

0.7

0.21

0.34

0.08

0.06

0.02

0.06

3.8

61

166

0.55

0.16

0.33

0.15

0.13

0.01

0.05

1.2

60

270

0.56

0.26

0.24

0.16

0.12

0.02

0.04

2.2

59

269

0.58

0.26

0.23

0.14

0.11

0.02

0.04

2.3

58

156

0.69

0.23

0.29

0.13

0.06

0.02

0.05

3.6

57

170

0.67

0.21

0.3

0.13

0.08

0.01

0.07

2.3

56

228

0.74

0.44

0.15

0.1

0.05

0.01

0.07

7.7

55

279

0.48

0.25

0.11

0.23

0.18

0.003

0.08

1.4

54

243

0.54

0.26

0.19

0.16

0.12

0.004

0.08

2.1

53

295

0.67

0.23

0.28

0.11

0.09

0.003

0.12

2.6

52

33

0.48

0.15

0.12

0.18

0.15

0.03

0.27

0

51

78

0.44

0.03

0.26

0.06

0.05

0.01

0.15

0.75

50

83

63%

0.27

0.28

0.04

0.04

0

0.06

7.3

49

130

0.44

0.19

0.2

0.16

0.15

0.01

0.07

1.25

48

62

0.26

0.08

0.08

0.32

0.3

0.02

0.08

0.26

47

63

0.33

0.09

0.14

0.3

0.29

0.02

0.08

0.33

46

104

0.57

0.26

0.14

0.18

0.17

0.01

0.12

1.5

45

130

0.51

0.22

0.11

0.17

0.15

0.01

0.2

1.4

44

120

0.54

0.18

0.11

0.21

0.18

0.03

0.2

1

43

134

0.43

0.19

0.12

0.2

0.16

0.01

0.12

1.1

42

101

0.39

0.05

0.3

0.27

0.25

0.02

0.06

0.2

41

176

0.54

0.15

0.35

0.12

0.11

0.01

0.11

1.4

40

101

0.62

0.23

0.28

0.16

0.15

0.01

0.06

1.5

39

60

0.5

0.08

0.27

0.2

0.18

0

0.15

0.4

38

121

0.41

0.13

0.15

0.21

0.18

0.02

0.27

0.7

37

107

0.58

0.14

0.26

0.15

0.12

0.02

0.23

1.1

36

104

0.5

0.16

0.24

0.13

0.12

0.01

0.27

1.4

35

61

0.62

0.07

0.44

0.16

0.13

0.02

0.08

0.5

34

64

0.42

0.05

0.06

0.28

0.25

0

0.01

0.18

33

81

0.55

0.06

0.26

0.17

0.16

0

0.04

0.3

32

112

0.66

0.08

0.49

0.05

0.04

0

0.09

1.8

31

87

0.43

0.18

0.16

0.15

0.13

0

0.08

1.4

30

134

0.26

0.01

0.22

0.28

0.26

0

0.04

0.05

29

98

0.2

0.01

0.12

0.38

0.35

0

0.08

0.03

28

157

0.22

0.01

0.06

0.37

0.37

0

0.05

0.05

27

174

0.21

0.01

0.07

0.36

0.36

0

0.01

0.03

26

100

0.41

0.01

0.21

0.16

0.15

0

0.1

0.06

25

82

0.46

0.04

0.23

0.17

0.17

0

0.11

0.21

24

69

0.5

0.03

0.39

0.19

0.17

0

0.04

0.16

23

85

0.49

0.01

0.38

0.13

0.13

0

0.2

0.09

22

55

0.25

0

0.2

0.24

0.24

0

0.24

0

21

88

0.23

0.5

0.16

0.13

0.13

0

0.13

0.4

20

59

0.28

0.08

0.15

0.14

0.14

0

0.15

0.6

19

84

0.41

0.02

0.33

0.18

0.18

0

0.04

0.13

18

88

0.34

0.13

0.18

0.18

0.18

0

0.01

0.7

17

90

0.48

0.23

0.23

0.22

0.22

0

0

1.05

16

112

0.21

0.13

0.04

0.21

0.21

0

0.03

0.62

15

90

0.37

0.31

0.04

0.18

0.18

0

0.07

1.8

14

84

0.38

0.32

0.03

0.23

0.23

0

0.02

1.4

13

84

0.39

0.33

0.01

0.29

0.29

0

0.01

1.2

12

82

0.4

0.06

0.32

0.27

0.27

0

0.024

0.2

11

73

0.32

0.01

0.29

0.33

0.33

0

0

0.04

10

62

0.37

0.05

0.3

0.29

0.29

0

0

0.16

9

57

0.42

0.05

0.28

0.23

0.23

0

0.04

0.2

8

149

0.54

0.13

0.4

0.21

0.21

0

0.01

0.6

7

149

0.54

0.11

0.4

0.21

0.2

0

0.04

0.5

6

78

0.45

0.04

0.38

0.18

0.18

0

0.04

0.21

5

112

0.29

0.01

0.28

0.26

0.26

0

0.04

0.03

4

98

0.11

0.01

0.08

0.34

0.34

0

0.03

0.03

3

59

0.2

0.02

0.15

0.17

0.17

0

0.03

0.1

2

58

0.29

0.07

0.19

0.21

0.21

0

0.02

0.33

1

74

0.28

0.03

0.18

0.2

0.2

0

0.01

0.13

Fig. 7 Percentage distribution of Maastrichtian paleoecologic indicator nannofossil of Wadi El Dakhl succession


50%

100%

50%

100%

50%

100%

50%

100%

50%

100%

50%

100%

50%

Micula prinsii CC26

70 69 68 67 66 65 64 63

Micula murus CC 25 c

62 61 60 59 58 57 56 55 54 53 52 51 50 49

Lithraphidites quadratus CC 25 b

48 47 46 45 44 43 42 41 40 39 38 37 36

Sudr

35

Arkhangelskiella cymbiforms CC 25 a

Maastrichtian

34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17

Reinhardtites levis CC 24

Micula decussata / Watznaueria barnesae

Low productivity indicators %

High productivity indicators %

Watznaueria barnesae%

Warm water %

Arkhangeleskiella cymbifornis %

Micula decussata%

2547

Cool water %

Sample No.

Zone

Formation

Age

Arab J Geosci (2015) 8:2537–2550

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

Fig. 8 Percentage distribution pattern of Maastrichtian paleoecologic indicator nannofossil of Wadi El Dakhl succession

100%

5

10


essential for revealing paleoenvironments. The ratio of M. decussata (M. staurophora)/W. barnesae was used to detect paleotemperature variations (Wind 1979). The ratio of M. decussata/W. barnesae was used by (Pospichal 1996; Ovechkina and Alekseev 2004; Guerra et al. 2012). In the present study, in the R. levis zone, the ratio of M. decussata/W. barnesae trends to increase from 0 to 1.8 with an average of 0.4. The ratio of M. decussata/W. barnesae in the A. cymbiformis zone fluctuates between 0.03 and 1.4 with an average of 0.5. In the L. quadratus zone, the M. decussata/W. barnesae ratio is represented by an average of 1.2. It fluctuates between 0 and 7.3. The ratio of M. decussata/W. barnesae in M. murus zone trends to increase from 1.2 to 7.7 with an average of 2.7. In the M. prinsii, the ratio of M. decussata/W. barnesae fluctuates between 2 and 3 with an average of 2.6 (Figs. 7 and 8).

Arab J Geosci (2015) 8:2537–2550

Lithraphidites quadratus ecozone It is characterized by moderate thickness (27 m), low abundance (98 individuals), dominance of cool-water forms (49 %), M. decussta (15 %), A. cymbiformis (21 %), warmwater (25 %), W. barnesae (16 %), the ratio M. decussta/ W. barnesae (1.2), high productivity (0.01 %), and low productivity (14 %) (Figs. 7 and 8). Micula murus ecozone In the studied succession, this ecozone is characterized by moderate thickness (19.5 m), high-abundance (232 individuals), predominance of cool-water taxa (62 %), M. decussta (24 %), A. cymbiformis (24 %), warm-water (14 %), W. barnesae (10 %), the ratio M. decussta/W. barnesae increased to 2.7, high productivity (0.01), and low productivity (14 %) (Figs. 7 and 8).

General discussion Micula prinsii ecozone The Maastrichtian and, in particular, Late Maastrichtian paleotemperatures have been studied extensively in the recent years (e.g., Tantawy 2003; Sheldon et al. 2010; Thibault and Gardin 2006, 2010). As the result of the previously discussed paleoecologic indicators for establishing temporal variations in paleoenvironmental conditions, each biostratigraphic zone established for the studied succession will be dealt with separately as ecozone (Mandur and Baioumi 2013), so we can subdivide the combined section into five nannofossil ecozones. The following succinct commentaries on the five studied ecozones are briefly presented in order to deduce their environments. The following ecozones based on the paleoecologic indicators. Reinhardtites levis ecozone In the studied succession, this ecozone is characterized by moderate thickness (39 m), low abundance (85 individuals), predominance of cool-water taxa (36 %), M. decussta (10 %), A. cymbiformis (22 %), warm-water (21 %), W. barnesae (21 %), the ratio M. decussta/W. barnesae is low (0.4), no high productivity, and low productivity (11 %) (Figs. 7 and 8). Arkhangelskiella cymbiformis ecozone This ecozone corresponds to the middle part of the studied succession, and it is characterized by thin thickness (12 m), low abundance (113 individuals), predominance of cool-water taxa (37 %), M. decussta (0.05 %), A. cymbiformis (18 %), warm-water (25 %), W. barnesae (24 %), the ratio M. decussta/W. barnesae is 0.5, no high productivity, and low productivity (0.5 %) (Figs. 7 and 8).

In the studied succession, this ecozone is characterized by thin thickness (7.5 m), high-abundance (336 individuals), predominance of cool-water taxa (56 %), M. decussta (34 %), A. cymbiformis (0.06 %), warm-water (21 %), W. barnesae (13 %), the ratio M. decussta/W. barnesae increased to 2.6, high productivity (0.05), and low productivity (10 %) (Figs. 7, and 8). During the Late Maastrichtian, the M. Prinsii, M. murus, and L. quadratus ecozones are characterized by a cooler (high-latitude) and relatively low productivity, high stress environment. In the Early Maastrichtian, R. levis and A. cymbiformis ecozones are characterized by a warmer climate, so the Early Maastrichtian sea surface temperature was much higher than that of the Late Maastrichtian. Similarly to this study, several authors record cooling event in the Latest Maastrichtian (Pospichal 1996; Melinte et al. 2003).

Conclusions The present study deals with the lithostratigraphy, biostratigraphy, and paleoecology of the Maastrichtian succession of the western coast of the Gulf of Suez, Egypt. Lithostratigraphically, the studied succession is recognized to the Sudr Formation. According to the stratigraphic range of the identified 44 calcareous nannofossil species, the studied succession is subdivided into five calcareous nannofossil zones from base to top which are as follows: R. levis, Arkhangelskiella cymbiformis, L. quadratus, M. murus, and M. prinsii. The studied succession may be subdivided into five parts, on the basis of cool-water nannofossil indicators, warm-water nannofossil indicators, productivity indicators, nannofossils


preservation, and the abundance of Micula and the ratio of M. decussata/Watznaueria barnesae. On the basis of the quantitative analysis of calcareous nannofossil, in the Early Maastrichtian, R. levis and Arkhangelskiella cymbiformis ecozones are characterized by a warmer climate. The cool-water, the low productivity, and the ratio of M. decussata/W. barnesae relatively increase in the Late Maastrichtian, suggesting that the paleoecologic parameters were able to tolerate cold surface water conditions during the Late Maastrichtian.

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